A Deep Narrow Band Imaging Search for CIV and HeII Emission from
Lyman Alpha Blobs
Fabrizio Arrigoni Battaia; Y. Yang; J.F. Hennawi; Y. Matsuda; T.Yamada; T.Hayashino
MPIA, Heidelberg, Germany
Email: arrigoni@mpia-hd.mpg.de
The Lyman-alpha blobs ("LABs") are giant (> 100 kpc) luminous (>
1043 erg/s) Ly-alpha emitting nebulae at high redshift. Despite
significant theoretical and observational work, including new surveys,
the mechanism powering their emission remains a mystery. Several
scenarios, such as photoionization by an obscured AGN, gravitational
cooling radiation, or a thermalized superwind, have been proposed, but
discriminating between them requires additional diagnostics besides Lyman
alpha emission. In this Poster we show the results of the analysis of very
deep (about 20 hours) narrow band images at the wavelengths matching the
CIV (1549 A) and HeII (1640 A) emission lines in the SSA22
Proto-cluster field at z=3.1. The data were obtained with the VLT/FORS2
instrument using the SII (HeII) and OI/2500 (CIV) filters targeting a
region of 7'x 7' where 13 LABs and 30 Ly-alpha Emitters (LAEs) can be
observed simultaneously in a single pointing. We then compare our results
and the data in the literature with photoionization models from a central
QSO (Cloudy).
Distance Estimations of Low Redshift Active Galaxies
Vijayakumar Doddamani;
P. Vedavathi
Department of Physics, Bangalore University, Bangalore, India
Email: drvkdmani@gmail.com
Active galaxies are the most luminous objects observed in the Universe. Active Galaxies are powered by accretion processes taking place surrounding Super massive black at the center of these galaxies. However, the details of the power generation mechanisms are not completely understood well. A key factor for the limitations in our understanding these issues lies in the accurate distance estimations of active galaxies. The low redshift galaxies are interesting objects as we can easily verify our distance estimations with values obtained by alternative methods. We have chosen about 100 IUE observed low redshift active galaxies for the studies and their distances have been calculated using luminosity-distance relation with Hubble constant H0=75 Km/Sec/Mpc and acceleration parameter q= - 0.5. We have found out a systematic increase in the distances of low redshift galaxies compared to the calculations done by using deceleration parameters as q = 0.5. The distance calculations are consistent with the accelerating universe model of the cosmos. The detailed discussion on the significance/implications of these calculations on luminosities of active galaxies will be presented in the meeting.
Keywords: Active galaxies, Super massive black holes, Accretion processes, low redshift,
distances and luminosities
Morphology the sample
of active galaxies from SBS
Lidia Erastova
Byurakan Astrophysical Observatory (BAO), Armenia
Email: lke@bao.sci.am
The sample of the nearest active galaxies from Second
Byurakan Sky Survey (SBS) is presented. It includes 130 galaxies with z<0,01. There are as a rule dwarf galaxies and its dimensions
don’t exceed about 10 kpc. The morphology of these galaxies and its active
regions studied on the SDSS images. It was shown that active burst regions may
appear in each regions of the galaxy and form clump,
comet-like and other structures. If we consider the inclination of such formations
to the sky plane it can bring all such to the single picture, when the
distribution of active objects is randomly on the plane along galaxy or its
part.
We extract ~20 huge HII regions as SBS objects.
Their host galaxies may be either active or not. It is shown that number of
such burst regions likely much more if take into account, that similar objects
may exist in dwarf galaxies and don’t restrict its by luminosity.
The physical conditions and oxigen and nitrogen abundance of 36 SBS galaxies from the SDSS DR7
Marietta V. Gyulzadyan; V.Z. Adibekyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: mgyulz@bao.sci.am
Physical conditions and oxygen and nitrogen abundances in 36 SBS UV-excess and/or emission-line galaxies from the SDSS DR7 were determined. We have found that SBS 0808+578 is AGN. The others are HII galaxies or HII regions in galaxies. For all objects the oxygen abundance 12+log(O/H) lies in the range of 7.85 ÷ 8.61 and log(N/O) ratio in the range of -1.45 ÷ -0.4. They occupy the same area in the diagram N/O–O/H as the high-excitation HII regions. We found no extremely metal-deficient galaxy. Using Hα fluxes star formation rates (SFR) for our samples galaxies were determined. Determined SFRs, being in the range of 0.001 ÷ 6 Мo year-1, are similar of that observed in typical star forming regions in spiral and irregular galaxies.
Complex Investigation
of SBS Galaxies in Seven Selected Fields
Susanna Hakopian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: sanna@web.am
It is known that the main criterion for the selection
of active objects in the First Byurakan, otherwise Markarian
survey was the presence of signs of UV-excess in their low-dispersion spectra.
Using the presence of emission lines as the second criteria became real during
the Second Byurakan survey because of its improved technique. Extended (not
stellated) objects, selected with the use of this criterion, maid the main part
of the separate sample of SBS ⌠galaxies. Originally, this sample included
1632 objects, selected in 65 fields of the survey (16 square degree each), to
which, with the help of other sources than the survey, there were later added
some objects. We studied a subsample of SBS galaxies in seven selected fields
(the deepest according to the V/Vmax criterion), including about the third of
the whole sample. The first, already completed phase of this program was
started with carrying out a follow-up slit spectroscopy of all, about 500
objects, based on observations with long-slit spectrographs with 6m telescope
of SAO Russia and 2.6.m telescope of Byurakan. As a result redshifts were
determined, as well as spectral classification was made for all of objects,
using the scheme adapted to the spectral material. Besides other, obtained data
allowed us to estimate the efficiency of used criteria for the selection of
galaxies of different classes of starformation and nuclear activity along the
full scale of the apparent magnitudes, including close to the limit values
(18.5<mpg<19.5), etc. The fact that the total area of seven fields as the
total number of objects in them comparable with these values for the
survey as a whole, allows us to extrapolate the results to the whole sample of
galaxies as an upper estimate. The second stage is to conduct
detailed studies of individual galaxies in the first place, the most interesting
in terms of morphology. They are based on panoramic spectroscopy obtained from
observations at 6 m telescope of Russia and 2.6m telescope of Byurakan carried
out with multipupil spectrographs MPFS and VAGR, correspondently. Processing of
the data obtained for more than twenty objects are at different stages.
Data Aanalysis of Variable Galaxy Kaz163
Emilya L. Karapetyan
Yerevan State University, Armenia
Email: emili56@rambler.ru
Kaz 163 is a close double galaxy. Its southern component S is compact, with a very blue nucleus, in which heated active processes take place. From time to time gas formations are ejected from it which behave themselves like emission components around the main emission lines Hα, Hβ around both from their long-wave and short-wave sides. The given article presents the spectral data of the new observations, which were carried out with the 2.6m telescope in the Byurakan observatory in September 2011. Besides, the data obtained by different authors in different periods of observations are brought in this article which are mostly owned by optical and X-ray regions. The interval of these spectral observations covers approximately 30 years. During this period of time rather strong changes took place concerning the half-widths, the equivalent widthds and the relative intensities of emission lines which can be clearly seen in table 1,2 and table 3. During the first observation in October 1981, lines [NII] λλ 6584,6548 were not visible in the spectrum of galaxy S. In 2001 they were already visible on the spectrum, and on the spectrum obtained in 2011 they already surpassed the intensity of intensity Hα. The magnitude of galaxy S is also changing: its nucleus is very blue and its U-B= -0m.63. In the soft X-ray spectral region (0.1-2keV) the flux of the radiation chaged by 45% during 55000 sec., and in the hard one (2-10keV) it changed up to 3.4 times. Photoindexis Г for the soft and hard regions in the spectrum of galaxy S, unlike other objects, do not differ from each other so much. The mean value for the first interval is approximately 2.5 and is equal -2.0 for the second one. On the histogram of redshifts Kaz 163 corresponds to the first big peak of the distribution.
It is concluded that the component S of galaxy Kaz 163, among the galaxies NLSI, with the development of their evolution, is in the preliminary stage. Component N is a normal elliptical galaxy with no activity.
Revised activity types
for Markarian galaxies
Areg M. Mickaelian; H.V. Abrahamyan; G.S. Harutyunyan; G.M. Paronyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: aregmick@aras.am
The sample of Markarian galaxies consists of 1515
UV-excess galaxies containing many active galaxies, both AGN and Starburst
(SB). Several catalogs of Markarian galaxies have been published; however
activity types are based on old spectroscopic data. The SDSS spectroscopy and some
other recent spectral observations allow classify or re-classify many of
Markarian galaxies, altogether we have retrieved and studied 779 SDSS and 300
other spectra. Out of 779 SDSS spectra, we have classified 533 HII, 31
Composites (LINER/HII, Sy/HII, Sy/LINER or Sy/HII/LINER), 12 LINERs, 4 Sy2.0, 5
Sy1.9, 8 Sy1.8, 5 NLS1.5, 11 Sy1.5, 8 NLS1.2, 21 Sy1.2, 4 NLS1, 4 Sy1.0, 2 QSO,
11 AGN (without an exact class), 52 Em (HII or AGN), 65 Abs, and 3 Stars. On
the other hand, the galaxies are being classified depending on the fact in
which wavelength range they have been observed and studied. E.g. some Sy2 type
galaxies turn to be Sy1 when classified in IR. Many hidden AGN (in X-ray and
IR) appear to be normal galaxies in optical range. So for better understanding,
IR spectra are necessary as well, and we plan to extract and study Spitzer
spectra too.
Dusty Active Galaxies
Nora Andreasian-Thomas
Thomas Research Institute, USA
Email: nora_ta@yahoo.com
Most astronomers know about B.E. Markarian’s discovery and further study of galaxies with UV excess. It is less known that in 1963 Markarian drew attention to a small group of galaxies with color index-spectral type discrepancy. Early spectral type of these galaxies is combined with large color index (e.g. M82). Later studies showed that galaxies with large intrinsic color indices (CI≥0.85) exhibit properties typical for active galaxies – galaxies with “red excess” are as active as galaxies with UV excess.
AKARI Infrared Camera
observations of the 3.3 um PAH feature in Swift/BAT AGNs
Angel Castro; T. Miyaji; M. Imanishi; M. Shirahata; T. Nakagawa; Sh. Oyabu; K. Ichikawa;
Y. Ueda
Instituto de Astronomia, Ensenada - Universidad Nacional Autonoma de
Mexico, Mexico
Email: acastro@astrosen.unam.mx
We explore the relationships between the 3.3
μm polycyclic aromatic hydrocarbon (PAH) and active galactic nucleus
(AGN) properties of a sample of 54 hard X-ray selected bright AGNs
- including both Seyfert 1 and Seyfert 2 type objects - using the
InfraRedCamera (IRC) on board the infrared astronomical satellite AKARI. The
sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of them have measured X-ray spectra at E ≤ 10 keV. Especially, these X-ray spectra provide measurements of the neutral hydrogen column density
(NH) towards the AGNs. We use the 3.3 μm PAH luminoosity
(L_3.3μm) as an indicator of star-formation activity and hard X-ray
luminosity L14-195keV as an indicator of the AGN
activity. We searched for possible difference of star-formation activity between type 1 (unabsorbed) and type 2
(absorbed) AGNs. We have made several regression analyses taking the
upper-limits of the PAH lines into account using the survival analysis package
ASURV. As a result, we do not find significant dependence in the
log(L3.3μm/M•) versus log(L14-195keV/M•) relation on the optical AGN type nor NH. We find apparent positive
correlation between log(L3.3μm/M•)
and log(L14-195keV/M•). However, it is not still clear whether
this apparent correlation reflects a selection effect or real underlying
between the Eddington ratio and the specific star-formation rate. We are extending
our analysis to longer wavelength PAH lines using archival Spitzer IRS spectra.
Analysis and
Statistics of the Spectroscopic Sample of Byurakan-IRAS Galaxies
Gohar Harutyunyan; A.M. Mickaelian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: goharutyunyan@gmail.com
The Byurakan-IRAS Galaxy (BIG) sample is the result of
optical identifications of IRAS PSC sources at high-galactic latitudes using
the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1278 objects
most are spiral galaxies and there is a number of ULIRGs among these objects.
Our spectroscopic observations carried out with three telescopes (BAO-2.6m,
SAO-6m and OHP-1.93m), as well as the SDSS DR7, DR8 and DR9 spectra make up the
list of 240 spectroscopically observed BIG objects. All but one have emission lines; we have discovered 70 AGN and composite
spectrum objects among them and the others are Starbursts. All possible
physical characteristics have been measured and/or calculated, including
physical sizes and optical and IR/FIR luminosities. The masses have been
estimated based on mass-luminosity relations for spiral galaxies. As it
appears, most of these objects are giant massive galaxies. Various
multiwavelength (MW) data have been retrieved from recent catalogs from X-ray
to radio and MW SEDs have been built, which have been matched to their optical
classifications. Luminosity evolution of these objects has been studies.
Investigation of
Extragalactic Radio Sources on the basis of Cross-Matching of Different Radio
Catalogs
Hayk Abrahamyan; A.M. Mickaelian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: abrahamyanhayk@gmail.com
We cross-correlate and investigate radio sources from
2 catalogs: NVSS and FIRST.NVSS catalog (Condon+ 1998) contains1.773.484
sources down to sensitivity 2.5 mJy over a surface ~34.000 square degrees with
accuracy of 15 arcsec rms and FIRST catalog (Version 2012Feb16, Becker+ 2012)
contains 946.464 sources down to sensitivity 1 mJy over a surface ~10.000
square degreeswith accuracy of 5 arcsec rms. We cross-correlate these 2
catalogs using new software (http://arvo.sci.am/crosscorrelation/crosscor.html).In this software we count errors for each source and take those
identifications with errors within 3 sigma. As a result we obtain a sample
allowing accomplish several tasks:
1. Some sources
have multiple identifications. Among them there may be objects with complex
structure: central part, radio lobes and/or jets, which may be revealed by
multiple FIRST sources associated with single NVSS source.
2. For some
identifications, we have different fluxes at 1400 MHz from NVSS and FIRST.
These sources are considered to be variable radio sources and among them most
important are candidate blazars.
3.
Identifications with other radio catalogs (7C, WENSS, WISH, 87GB, GB6, etc.) to
have an opportunity to study these sources along the whole radio range;
understanding changes of fluxes in whole radio range and studying SEDs.
4.
Identifications with other catalogs will give opportunity to have information
in all fluxes in all wavelength range (ROSAT, GALEX, SDSS, 2MASS, WISE, IRAS,
AKARI, etc.). This information will give us opportunity to understand some
problems about radio sources.We findwhat fraction of radio sources has X-ray, UV, optical and IRcounterparts.
Radio Properties of
AGN
Hayk Abrahamyan; A.M. Mickaelian, G.M. Paronyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: abrahamyanhayk@gmail.com
To study the radio properties of AGN, we
cross-correlate and investigate Veron-Cetty & Veron catalog (v.13, 2010)
with NVSS, FIRST, GB6, 87GB, SUMSS, WISH, WENSS, 7C. This catalog contains
168.940 sources with accuracy of mostly 1 arcsec, though many objects have
larger errors.
We cross-correlate these all catalogs
using new software (http://arvo.sci.am/crosscorrelation/crosscor.html). In this software we count errors for
each source and take identifications with errors within 3
sigma. Altogether, we find some 40,000 AGN having radio detection. Using
all data from radio catalogs, we derive a homogeneous sample of radio AGN.
The sample allows accomplish several tasks:
1. Determine
AGN types and their fraction having radio detection: Blazar, QSO,
Sy1/Sy1.2/Sy1.5, Sy1.8/Sy1.9/Sy2, LINER, Composite, HII
2. Differences in physical properties of radio-loud
and radio-quiet AGN
3. Luminosity functions for various types of radio AGN
4. q parameter by AGN types
and its evolution
5. FRI and FRII sources among different types of AGN
6. Radio and optical variability of QSOs and other AGN
The study of some
morphological features of extragalactic radio sources of FRI and FRII types
Ruben Andreasyan; M. Hovhannisyan; G. Paronyan; H. Abrahamyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: randrasy@bao.sci.am
It was used the date of more than 650 extragalactic
radio sources for the study of distribution of spectral indexes and elongation
for the radio sources of different Fanaroff Riley (FR) classes. It was shown,
that no large differences are observed in the distribution of spectral indexes
in radio sources FRI and FRII classes. From the study of distribution of the
elongation of extragalactic radio sources it was found the following basic
morphological differences for the objects of different FR classes:
a) the radio images of
extragalactic radio sources FRII type in the average are more elongated than
the radio images of extragalactic radio sources FRI type:
b) the extragalactic radio sources FRI type can be
divided on two subtypes with two function of distribution of the elongation
parameter K having different maximums. These two subtypes of radio sources of
FRI class, in besides of different average elongation of radio images, probably
must have also differences in the orientations of these elongations directions
relative to the direction of rotation axes of parent optical galaxies that in
most cases are coincide with the minor optical axes of galaxies.
Multi-frequency,
multi-epoch VLBI observations of the M87 jet
Kazuhiro Hada; M. Giroletti; G. Giovannini; D. Akihiro; K. Motoki; N. Hiroshi; H. Mareki;
H. Yoshiaki; K. Noriyuki
INAF - Istituto di Radioastronomia, Italy
Email: hada@ira.inaf.it
The giant radio galaxy M87 is one of the nearest AGN
jet showing intense radiation through radio to VHE gamma-ray.
Its proximity and the large mass of the central
black hole provide an excellent advantage to probe the sites of jet formation
and gamma-ray production. VLBI observations at radio frequencies are a unique
tool to directly resolve such regions. We present recent progress on our study
of the M87 jet based on multi-epoch, multi-frequency VLBI observations. We
especially focus on the two distinct regions; the jet base near the black hole
and the peculiar jet feature HST-1 located at a large distance from the jet
base. We discuss the physical properties of these features obtained from these
observations.
The Lockman Hole
Project: Multi-frequency Study of the Faint Radio Population down to 150 MHz
Isabella Prandoni; G. Guglielmino; R. Morganti; G. Heald
INAF – IRA, Italy
Email: prandoni@ira.inaf.it
The Lockman Hole Project is a wide international
collaboration aimed at exploiting the multi-band extensive and deep information
available for the Lockman Hole (LH) region to better characterize the physical
and evolutionary properties of the various source populations detected in deep
radio fields (mainly star-forming galaxies and AGNs). In this general
framework, we present the current status of a multi-frequency study of the LH,
aimed at investigating the radio spectral properties of the faint radio
population as a function of flux density. In particular we are interested in
investigating the spectral flattening seen in deep radio fields, presumably
associated to self-absorbed core-dominated AGNs. In this respect particularly
interesting is a reliable assessment of the spectral index behaviour of faint
sources at frequencies <<1.4 GHz, where self-absorption effects can be
more prominent. For this purpose deep, wide-area observations at various
radio-wavelengths were carried out with both Westerbork (at 345 MHz and 1.4
GHz) and LOFAR (150 MHz). It is worth noticing that LOFAR allows us, for the
first time, to extend the spectral index analysis down to frequencies <<
300 MHz, a frequency domain never explored before at mJy and sub-mJy flux
densities. The LOFAR observations presented here were undertaken as part of the
commissioning of the telescope, and are to be considered as preparatory for the
deeper LH observations to be carried out as part of the LOFAR Survey
key-project.
The MASIV Survey:
Spectroscopic Identifications of Compact Radio Sources
Tapio Pursimo; R. Ojha; D. Jauncey; B. Rickett; M. Dutka; J. Koay; J. Lovell; H. Bignall; L. Kedziora-Chudczer; J.-P. Macquart
Nordic Optical Telescope, Spain
Email: tpursimo@not.iac.es
Intraday variability (IDV) of the radio emission from
active galactic nuclei is now known to be predominantly due to interstellar
scintillation (ISS). The MASIV (The Micro-Arcsecond Scintillation-Induced
Variability) survey of 443 compact flat spectrum sources revealed that IDV is
related to the radio flux density and redshift. A study of the physical
properties of these sources
has been severely handicapped by the absence of
reliable redshift measurements for many of these objects. In the recent paper
(arXiv:1302.3409) the optical identifications were presented
for a 73% complete sample. We found that 78% of the sources have broad
emission lines and are mainly FSRQs. About 16% are weak-lined objects,
chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross
properties (redshift, spectroscopic class) of the MASIV sample are similar to
those of other blazar surveys. However, the extreme compactness implied by ISS
favors FSRQs and BL Lacs in the MASIV sample as these are the most compact
object classes. We confirmed that the level of IDV depends on the 5 GHz flux density for all optical spectral types. We found
that BL Lac objects tend to be more variable than broad line quasars. The level
of ISS decreases substantially above a redshift of about two. The decrease is
found to be generally consistent with ISS expected for beamed emission from a
jet that is limited to a fixed maximum brightness temperature in the source
rest frame. With the new redshifts,
presented here, the sample is about 90% complete. The spectroscopic identification, and the ISS properties of the MASIV sample
are discussed based on this nearly complete sample.
Compton thick AGN in Chandra surveys
Murray Brightman; K. Nandra
MPE, Germany
Email: mbright@mpe.mpg.de
We present the results from the X-ray spectral analysis of active galactic nuclei (AGN) in the Chandra Deep Field-South, AEGIS-XD and Chandra-COSMOS surveys, focussing on the identification and characterisation of the most heavily obscured, Compton thick (CT, NH > 1024 cm-2) sources. Our sample is comprised of 3267 X-ray selected sources, which has a high rate of redshift completeness (96%). The aim is to produce the largest and cleanest uniform sample of these sources from the data as possible. We identify these sources through X-ray spectral fitting, utilising torus spectral models designed for heavily obscured AGN which self consistently include the spectral signatures of heavy absorption, being Compton scattering, photoelectric absorption and iron K-alpha fluorescence. We identify a total of 204 CT AGN covering an intrinsic 2-10 keV X-ray luminosity range of 1042 -3 x 1045 erg s-1 and from z=0.1-7, enabling us to characterise these heavily obscured AGN across cosmic time and ascertain their cosmological significance. These survey fields are the sites of extensive multi-wavelength coverage, including near-infrared CANDELS data and far-infrared Herschel data, enabling forthcoming investigations into the host properties of CT AGN. Our work also includes improved photometric redshifts from CANDELS. Our analysis of the X-ray spectra shows that that the torus covering factor increases with LX for all redshifts, consistent with the receding torus model, and that for constant LX, this factor increases with redshift. We come to this conclusion from the prevalence of the torus model with the smallest opening angle as the best t model for sources at low luminosity and at high redshift. Furthermore, the strength of the soft X-ray emission, believed to originate within the opening of the torus, and thus dependent on the covering factor, increases with luminosity and decreases with redshift with respect to the intrinsic emission of the AGN. The strong relationship between the parameters of obscuration and LX points towards an origin local to the AGN, arguing against larger scale obscuration by the host galaxy.
The XMM-Newton spectral-fit database
Amalia Corral; I. Georgantopoulos; S. Rosen; M.G. Watson; A. Akylas; ESA PRODEX project in collaboration with the XMM-Newton Survey Science Center (XMM-SSC)
National Observatory of Athens (NOA), Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS), Greece
Email: acorral@noa.gr
The XMM-Newton serendipitous source catalogue is the largest catalogue of X-ray sources built to date. In its latest version, the 3XMM-Newton catalogue, it contains more than half a million sources, for which photometric data have been derived. For more than 100,000 of them, spectral products have also been extracted. The XMM-Newton spectral-fit database contains spectral fitting results for most of the X-ray sources within the 3XMM catalogue for which spectral data are available. The database has been constructed by making use of automated spectral fits. This automated process has been extensively tested and scientifically validated in order to derive the most relevant spectral information for every X-ray source. As a result, the XMM-Newton spectral database represents an unique tool for the astronomical community to construct large and representative samples of X-ray sources by selecting them according to their spectral properties.
The Correlation between the Gamma-Ray Luminosity and the
Core-Dominance Parameters for a Fermi Blazar Sample
Junhui Fan; J.H. Yang; D.X. Wu; S.H. Li; Y. Liu
Center for Astrophysics, Guangzhou University, China
Email: fjh@gzhu.edu.cn
In this work, we investigated the correlation between the γ-ray luminosity,
logLγ and the core-dominance parameter, log(1 + R), for a sample of Fermi
blazars with available core and extended radio emissions. Our analysis shows
that there is no correlation between the γ-ray luminosity, logLγ and the coredominance parameter, log(1 + R). However, there is a closely linear correlation
between logLγ − logLExt and log(1 + R), logLγ − logLExt = (0.95 ± 0.08)log(1 + R) + (2.72 ± 0.11),
with a correlation coefficient r = 0.73 and a chance probability of p < 10−4, for the whole sample. The result suggests that the γ-ray emissions are composed of
two components, one is beamed, the other is unbeamed.
Acknowledgements: The work is partially supported by the National Natural Science Foundation of China
(NSFC 10633010, NSFC 11173009), the Bureau of Education of Guangzhou Municipality(No.11 Sui-Jiao-Ke[2009]), Guangdong Province Universities and Colleges Pearl River
Scholar Funded Scheme(GDUPS)(2009), Yangcheng Scholar Funded Scheme(10A027S), and
support for Astrophysics Key Subject of Guangzhou City.
The ROSAT/NVSS AGN
sample
Gurgen Paronyan; H. Abrahamyan; G. Harutyunyan; A. Mickaelian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: gurgen@bao.sci.am
ROSAT Bright Source Catalogue (BSC) contains 18,806
and ROSAT Faint Source Catalogue (FSC), 105,922 X-ray
sources.However, one source is listed twice giving the total number of
ROSAT X-ray sources 124,727. On the other hand, NVSS radio catalogue contains
1,773,484 sources. Taking into account that X-ray sources contain AGN, bright
stars and galaxies, clusters, white dwarfs (WD), cataclysmic variables (CV),
etc., the cross-identification with radio catalogue may distinguish the
extragalactic sources. We have cross-correlated ROSAT catalogs with NVSS one with
a search radius 30". 9193 associations have been found.
To distinguish AGN from the normal bright galaxies and clusters The
Veron-Cetty&Veron AGN catalog (v.13, 2010; VCV-13) contains 168,940
objects.A cross-correlation of the 9,193 ROSAT/NVSS sources with the VCV-13
with a search radius 30" resulted in
3,094associations. Thus we are left with more 6,099 X-ray/radio sources without
an optical identification. Brighter objects are normal bright galaxies, while
we believe that all faint ones are candidate AGN with some contamination of
distant clusters. SDSS spectroscopic survey allows us classify objects by
activity types, and a number of our candidate AGN is found to be present in
SDSS.
Activity types for
X-ray candidate AGN from SDSS
Gurgen Paronyan; G. Harutyunyan; A. Mickaelian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: gurgen@bao.sci.am
The Joint Catalog of Hamburg ROSAT Sources (JCHRS) is
the result of merging of HRC and BHRC catalogs built on the basis of ROSAT-BSC
and ROSAT-FSC sources. Altogether, are present. From them, we have created a sample
of ROSAT AGN, including the candidate ones. In this paper we classify AGN
candidates by activity class, which previously had not been determined using
the spectral classification, altogether X-ray selected 955AGN candidates,with
count rate of photons CR > 0.04 ct/s in the area with galactic latitudes
|b|>30 and declinations δ>0. 210 sources out of 955 AGN candidates
have SDSS spectra. The results of the classification are: genuine AGN - 92,
absorption-line galaxies - 79, stars - 32, unknown spectra- 7. We are
going also to make detailed studies of other 745 sources in order to be able to
confirm their AGN nature and that will help us to use this method to reveal new
AGN candidates.
Study of Homogeneous
X-ray AGN sample
Gurgen Paronyan; A. Mickaelian; H. Abrahamyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: gurgen@bao.sci.am
In this paper we attempt to create a common catalog of
X-ray selected active galactic nuclei (AGN). For this, HRC (Hamburg RASS
Catalog) and BHRC (Byurakan Hamburg RASS Catalog) have been used made up on the
basis of optical identification of X-ray sources from ROSAT catalogs based on
low-dispersion spectra of Hamburg Quasar Survey (HQS), ROSAT Bright Source
Catalogue (BSC) and ROSAT Faint Source Catalogue (FSC), respectively. As a
result, a new sample of X-ray selected AGN, which contains 4333 X-ray sources
with photoncount rate CR > 0.04 ct/s in the area with galactic latitudes
|b|> 30 and declinations delta>0. All these sources are classified as AGN
or their candidates. We have made
multiwavelength investigation in several wavelength ranges (X-ray, optical,
radio). In order to make identifications, we used those catalogs, which more or
less guarantee the completeness condition (all-sky surveys). A number of
classification errors were found(some AGN has been
classified as stars or galaxies). The number of such objects is 1024 and 59
from HRC and BHRC, respectively. Out of 4333 sources, 3378 arespectroscopically
confirmed AGN (given in Veron-Cetty&Veron and Roma Blazar catalogs), and
the rest 955 are AGN candidates.For 210 of AGN candidates spectra are available
in SDSS DR9, and the results of their classification are given in another
research. We calculated the absolute magnitudes, fluxes, approvedcoordinates
and redshifts. An attempt is made to find a connection between the radiation
fluxes in different bands for different types of sources, and identify their
characteristics, and thus confirm the candidate AGN.
X-ray galaxies in
nearby filaments
Anatoliy Tugay
Taras Shevchenko National University of Kyiv, Ukraine
Email: tugay.anatoliy@gmail.com
New sample of X-ray galaxies selected from 2XMMi
catalogue in SDSS region is analysed in this work. Spatial distribution and
X-ray AGN spectral properties are discussed. A new method for extragalactic
filament detection and description is proposed.
The sharpest view of
the local AGN population at mid-infrared and X-ray wavelengths
Daniel Asmus; P. Gandhi; S. Hoenig; A. Smette; W. Duschl
Max-Planck-Institut fur Radioastronomie, Germany
Email: asmus@mpifr.de
We present the largest mid-infrared (MIR) atlas of active galactic nuclei at subarcsec spatial scales containing 253 objects with a median redshift of 0.016. It comprises all available ground-based high-angular resolution MIR observations performed to date with 8-meter class telescopes and includes 895 photometric measurements. Subarcsec resolution allows us to isolate the emission of the AGN on scales of a few tens of parsecs for the bulk of the sample and obtain nuclear photometry in multiple filters for the objects.
All types of AGN are present in the atlas, which also includes 80% of the 9-month BAT AGN sample. Therefore, this atlas and its subsamples are very well-suited for AGN unification studies. For example, we investigate differences in the MIR properties of the AGN classes, such as emission compactness, spectral energy distributions and star-formation contributions on nuclear scales. Finally, we discuss the enlarged MIR--X-ray correlation, which extends over six orders of magnitude in luminosity and potentially probes different physical mechanisms.
Optical polarization
of gamma-ray bright blazars
Dmitry Blinov; E. Angelakis; M. Balokovic; L. Fuhrmann; T. Hovatta; K. Katarzyski;
P. Khodade; O. King; A. Kus; N. Kylafis; I. Myserlis; G. Panopoulou; I. Papadakis; I. Papamastorakis; V. Pavlidou; B. Pazderska; E. Pazderski; T. Pearson;
C. Rajarshi; A. Ramaprakash; A. Readhead; P. Reig; R. Rouneq; K. Tassis; A. Zensus
University of Crete, Greece
Email: dmitriy.blinov@gmail.com
We report about first results of the RoboPol project.
RoboPol is a large-sample, high-cadence, polarimetric monitoring program of
blazars in optical wavelengths, using a camera specifically constructed for
this project, mounted at the University of Crete's Skinakas Observatory 1.3 m
telescope. The analysis of RoboPol data is conducted in conjunction with Fermi
LAT gamma-ray data, and multifrequency radio data from the OVRO (Caltech),
F-GAMMA (MPIfR), and Torun (NCU) monitoring programs.
Using carefully selected samples of gamma-ray
bright and weak blazars we investigate a connection between their optical
polarization behaviour and variability properties in gamma. We examine a relationship
of gamma flares with polarization angle rotations relying on robust statistical
criteria. We analyse also the optical polarization variability itself in order
to establish some restrictions on physical models of blazars jets.
Fitting Spectral Energy Distributions of Obscured AGN: A Markov Chain Monte Carlo technique
Gabriela Calistro Rivera; J. Hennawi; E. Lusso; D. Hogg
Max Planck Institute for Astronomy, Germany
Email: calistro@mpia-hd.mpg.de
We present a Markov Chain Monte Carlo algorithm developed to fit the spectral energy distribution (SEDs) of active galactic nuclei with different AGN models. This code is well suited to determine in a robust way multiple parameters and their uncertainties, which quantify the physical processes responsible for the multi-wavelength nature of active galaxies and quasars. These parameters are among others age, bolometric luminosity, dust reddening, stellar mass and star formation rates. We describe the technicalities of the code and test its capabilities in the context of AGN classification due to obscuration, comparing it with other existing methods in this context. We attempt with the MCMC algorithm to classify obscured AGN among sources of the XMM-COSMOS survey.
Knowledge Discovery
workflows for the classification of AGNs in multiwavelengtháspaces: the
Blazars case
Raffaele D'Abrusco; F. Massaro; A. Paggi; G. Fabbiano
Harvard Smithsonian Center for Astrophysic (CFA), Harvard, USA
Email: dabrusco@gmail.com
The development of new AGNs selection techniques based
on the massive multi-wavelength datasets that are becoming more and more
frequent in astronomy is a crucial task to gather statistically significant
samples and shed light on the physical nature of this diverse class of
extragalactic sources. Novel characterizations of specific classes of sources
from unexplored region of their spectrum and unusual combinations of the
observational parameters can translate into new classification criteria. In this
innovative data environment, the whole process ranging from the discovery of
new patterns to the application of such patters to the selection of new AGNs, has to be tackled using a Knowledge Discovery (KD)
workflow. A KD workflows is a combination of different
KD methods that automatically extract the more interesting patters from data,
reduce the complexity of the dataset and provide astronomers with the simplest
possible amount of information to be interpreted. In this talk, I will describe
an original KD workflow which, in one of its first applications, has led to the
discovery of a previously unknown peculiar pattern followed by blazars in the
mid-Infrared color space (the blazars WISE locus), and the development of a new
classification criterion based on this pattern and useful to tackle different
problems. The comprehensive KD workflow used to derive these results
encompasses unsupervised methods for the exploration of the multi-dimensional
observable spaces, and supervised method for the training and optimization of
classifiers based on the patterns determined in the observable spaces. In
particular, I will describe the new methods for the association of unidentified
gamma-ray sources and the extraction of candidate blazars from mid-Infrared
photometric catalog based on the WISE blazars locus.
Ultraviolet
Line-Continuum properties in Seyfert 1 galaxies and quasars
Vijayakumar Doddamani;
P. Vedavathi
Department of Physics, Bangalore University, Bangalore, India
Email: drvkdmani@gmail.com
Active galaxies are most luminous objects in the
universe whose spectra are characterized by both permitted and forbidden
emission line features. The spectra of Seyfert 1 galaxies and quasars contain
strong and broad emission lines of wide ranging ionization potentials. The
velocity widths of the lines range from a minimum of ~ 500 km/s to a maximum of 10,000 km/sec. The Ultra Violet spectra of
these active galaxies contain strong and broad emission lines such as Lyα, NV, SiIV, OIV], CIV, CIII] and MgII lines. The widths of the broad
lines are attributed to the differential Doppler shifts of the emission lines
due to the bulk motions of individual line emitting clouds. In order to
understand the nature of dependence of the emission line properties with the
underlying continuum line emissions we have undertaken the studies of the line
luminosity correlations Lyα and CIV lines with the underlying UV
continuum luminosity using the UV spectral data IUE satellite. The redshift of
the objects selected in the present study is in the range of z = 0.1 to 2.5
with absolute V magnitudes from -23 to -30. We have reduced the
IUE archival spectra for dispersion, galactic reddening and the redshift of
active galaxies using the tasks of IRAF software. These spectra have been used
for measuring the line and continuum fluxes. We have calculated the line and
continuum luminosities in the wavelength range of 1100Å to 3000 Å. A varying degree of linear correlations have been obtained for
different lines at different UV continuum. The Lyα line has shown strong
linear correlation at 1125 Å and 1425 Å wavelengths while CIV line has shown at 1425 Å and 2625 Å wavelengths. These results are empirically consistent with the
predictions of the photoionization models. These results suggest that the broad
emission lines are truly emitted by the photoionzation processes of BLR gas by
the strong UV continuum from central engine. We feel that these results would
become useful in the construction/constraining of BLR models. A detailed
account of the data reduction, flux measurement and luminosity calculations and
the significance of the linear correlations etc., are discussed in this paper.
The Chandra 3C
Snapshot Surveys
Daniel E. Harris; F. Massaro
SAO, Cambridge, MA, USA
Email: harris@cfa.harvard.edu
The Chandra X-ray Observatory is the only X-ray
facility with sub arcsec resolution, permitting detailed studies of radio
galaxies and quasars. We review a short list of projects contributing to our
goal of obtaining Chandra observations of all 3C extragalactic sources. Radio
source samples, unlike most surveys at other wavelengths, should be completely
unbiased with respect to viewing angle: the radio lobes are sign posts
indicating the location of AGN (obscured or unobscured nuclei). The X-ray data
allow us to estimate excess absorption towards nuclei, to find new examples of
X-ray emission from jet knots and hotspots, and to isolate sources in clusters of
galaxies together with signatures of feedback (e.g. cavities in the ICM). This
work is supported by NASA grants GO1-12125A and GO2-13115X.
Wide-field observations in SDSS Stripe 82 with EVN
Cao Hongmin; L. Gurvits, J. Yang, X. Hong
Shanghai Astronomical Observatory, Chinese Academy of Sciences, China
Email: hmcao@shao.ac.cn
We observed an area of sky located within the SDSS Stripe 82 field at 1.66 GHz using the
multiple-phase-centre mode of the European VLBI Network (EVN) in a combination with in-
beam and nodding phase referencing. There are fifteen mJy/sub-mJy radio sources within the
primary beam of a typical EVN radio telescope. Our aim was to obtain VLBI images of all
detectable sources within this primary beam area. The source of particular interest is a newly
found radio quasar SDSS J222843.54+011032.2 (SDSS J2228+0110) at z ∼ 5.95. The data
correlation was performed at the JIVE software correlator SFXC. The total of three targets, in-
cluding the extremely high-redshift radio-loud quasar mentioned above, were detected, all three
with the position offsets not exceeding the 3σ accuracy of the original low resolution surveys.
The detection rate of 20% is consistent with other wide-field VLBI experiments carried out re-
cently. The project presented here demonstrates the ability of the EVN in multiple-phase-centre
experiment and paves the way for future massive surveys of compact structures in extragalactic
radio sources using the multiple-phase-centre VLBI techniques.
The Investigation of
Distant Quasars
Martik Hovhannisyan; R. Andreasyan; G. Paronyan; H. Abrahamyan
Institute of Applied Problems of Physics, Yerevan, Armenia
Email: martik@bao.sci.am
In the present paper for the study the physical and
morphological characteristics of distant quasars we do a radio-optical
investigation of (chosen from the second area ( 0.097
radian squares) of Cambridge 7C catalogue) quasars with angular sizes less than
an arc-second. For these objects, have been calculated average values of
absolute magnitudes and spectral indexes (M = -26,51±0,25 , alpha= 0,662±0,250 ). 60% of compact
radio sources from the FIRST catalogue ( 1400 MHz )
are candidates of quasars.
A Unified
Multi-Wavelength Radio and Optical Catalog of Quasars and Radio Galaxies
Amy Kimball; Z. Ivezic
CSIRO Astronomy and Space Science, Australia
Email: Amy.Kimball@csiro.au
We have constructed a publicly available unified catalog of radio
sources detected by GB6 (6cm), FIRST (20cm), NVSS (20cm),
WENSS (92cm), VLSS (4m), and SDSS DR9 (optical). The catalog
has over 2 million objects detected by FIRST and/or NVSS, and
nearly 12,000 detected by all five radio surveys. The 20 cm radio fluxes are used to efficiently categorize sources into
three classes of radio morphology. Radio color-magnitude-morphology
distributions show a clear structure suggesting strong underlying physical
correlations. Roughly one third of sources have an
optical counterpart, and so can be classified as galaxy (resolved) or quasar
(unresolved). Using a subset of approximately 20,000 sources detected at 92 and
20 cm, as well as optically, I am developing an AGN sample with well-understood
distributions in redshift, size, luminosity, and spectral index for comparison
with semi-analytic cosmological models as a test of underlying AGN physics and
the Unification Paradigm.
Size Measurements of
the Quasar X-Ray Continuum Emission Region by Analysis of Microlensing in
Chandra Imagery
Chelsea MacLeod; Ch. Morgan; Ch. Kochanek; M. Tewes; F. Courbin
United States Naval Academy, Annapolis, USA
Email: macleod@usna.edu
Microlensing offers a unique way to constrain the
physical extent of different emission regions in a lensed quasar, putting to
test various accretion and continuum emission models. We perform a joint
microlensing analysis using six Chandra observations (spanning six years) of
the lensed quasar SDSS 0924+0219, in which X-ray microlensing variability is
detected with high confidence, and high-cadence r-band monitoring (spanning
eight years). Our joint microlensing analysis provides robust constraints on
the extent of the X-ray continuum emission region and the accretion disk
radius, disfavoring models involving an extended X-ray corona.
Clustering and Halo
Occupation Distribution of Active Galactic Nuclei
Takamitsu Miyaji; M. Krumpe; A. Coil; H. Aceves; B. Husemann
Inst. de Astron. sede Ensenada, Univ. Nacional Autonoma de Mexico and UCSD CASS, Mexico/USA
Email: miyaji@astrosen.unam.mx
We present the results of our series of studies on correlation
function and halo occupation distribution of AGNs utilizing data the ROSAT
All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift
range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we
take cross-correlation approach, where cross-correlation functions (CCF)
between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are
analyzed using the Halo Occupation Distribution (HOD) model, where the
CCFs are divided into the term contributed by the AGN-galaxy pairs that reside
in one dark matter halo (DMH), (the 1-halo term) and those from two different
DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter,
which is a function of the typical mass of the DMHs in which AGNs reside. The
combination of the 1-halo and 2-halo terms gives, not only the typical DMH
mass, but also how the AGNs are distributed among the DMHs as a function of
mass separately for those at the center of the DMHs and satellites. The main
results are as follows: (1) the range of typical mass of the DMHs in various
sub-samples of AGNs log
(MDMH/h-1MΘ) ~ 12.4-13.4, (2) we found a dependence of
the AGN bias parameter on the X-ray luminosity of AGNs, while the optical
luminosity dependence is not significant probably due to smaller dynamic range
in luminosity for the optically-selected sample, and (3) the growth of the
number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or
even may be flat, contrary to that of the galaxy population in general, which
grows with MDMH proportionally, suggesting a suppression of AGN
triggering in denser environment. In order to investigate the origin of the
X-ray luminosity dependence, we are also investigating
the dependence of clustering on the black hole
mass and the Eddington ratio, we also present the results of this
investigation.
Chandra Observation of
the AKARI NEP Deep Field
Takamitsu Miyaji; M. Krumpe; H. Brunner; AKARI NEP Deep
Survey Team
Inst. de Astron. sede Ensenada, Univ. Nacional Autonoma de Mexico and UCSD CASS, Mexico/USA
Email: miyaji@astrosen.unam.mx
The AKARI NEP Deep Field Survey is an international multiwavelength survey over 0.4 deg2 of the sky. This
is the deepest survey made by the InfraRed Camera (IRC) of the infrared astronomical satellite AKARI with 9 filters
continuously covering the 2-25 μm range. This has been supplemented by other ground-based and space
multiwavelength data ranging from X-ray (Chandra), UV (GALEX), Optical-NIR (Subaru Sprime-cam,
CFHT/WIRCAM, CFHT/Megacam, KPNO Flamningos among others for imagings as well as Keck Diemos, Subaru Focas, Subaru
FMOS, WIYN Hydra, and GTC OSIRIS for spectra), far-infrared (Herschel) and radio (WSRT and e-Merlin).
The uniqueness of the field lies in the availability of four filters between 9-18 μm, which fall into the
Spitzer gap between the IRAC and MIPS instruments. This made this field one of the deepest at ~ 15μm and
the deepest among those with similar solid angles. This enabled us to make sensitive MIR detection of AGN candidates
around z ~ 1. The MIR selection is based on hot dust emission in the AGN torus and is efficient in detecting
highly obscured Compton-thick AGN population. A number of team members have worked (e.g. Hanami et al. 2012) or
are working on a catalog of AGN candidates in this field.
In this presentation, we report the results of the Chandra observations on this field. The field was covered by 15
overlapping Chandra ACIS-I observations (including our own and from archive) with a total exposure of 310 ks, detecting
~ 500 X-ray sources. We explain our improved source detection procedure for highly overlapped Chandra images and
results. We utilize the stacking analysis (both in the observed and rest-frame) of the MIR AGN candidates that are not
detected individually. The stacking analysis is expected to detect the summed X-ray flux from scattered components and
Fe-lines. The results are discussed in terms of quantifying the Compton-thick populations at z ~ 1.
Searching for obscured
AGN using WISE and XMM-Newton
Manolis Rovilos; I. Georgantopoulos; A. Akylas; D. Alexander
Durham University, United Kingdom
Email: emmanouil.rovilos@durham.ac.uk
We conduct a wide search for obscured AGN using the XMM-Newton serendipitous survey combined with the SDSS DR7. To select the obscured AGN candidates we utilise the WISE all-sky survey and choose sources which have unusually high infrared to X-ray luminosity ratios. Using the near- and mid-infrared photometry information provided in the WISE catalogue we fit the SEDs of the X-ray matched WISE sources with a combination of an AGN and a host template, in order to isolate the AGN mid‐infrared (12-micron) emission, and compare it to the X-ray luminosity. The selected sample of 31 candidate heavily obscured AGN has mid-infrared colours resembling those of X-ray QSOs, and not Seyferts, despite their modest X-ray luminosities (Lx < 1044 erg/s), indicating that their intrinsic Xray luminosities are higher. We also analyze their X-ray spectra from the XMM-Newton counts and find that at least 9 of them are bona fide Compton-thick AGN, having a prominent Fe-Kα line, a flat spectrum, a spectrum best fitted with a reflection component, or a combination of these features. We finally compare this number with the expected number of Compton-thick sources from population synthesis models and compare their properties with what expected from evolutionary models of the universe invoking AGN feedback.
Further determination
of interband lags between variations in B, V, R, and I bands in active galactic
nuclei
Sergey Sergeev
Kiev National University, Crimean Astrophysical Observatory, Ukraine
Email: sergeev@crao.crimea.ua
New estimates of the interband lags between variations
in the B band and variations in
the V, R, and I bands for ten active
galactic nuclei are present. These AGNs were
observed at the Crimean Astrophysical Observatory as a part of the international monitoring campaign
over a 140-day span beginning in 2010 August. For the two nuclei, 3C 390.3 and Mrk
6, the interband lags are measured for a much longer time interval of several years and the effect of the
contribution of the broad Balmer lines to the bands are taken into account. The
obtained results are discussed in terms of the thermal reprocessing of the
X-ray emission in the accretion disk.
Multiwavelength
Observations of 6 FSRQ objects in 2008-2012
Ivan Troitskiy; I. Agudo; D. Blinov; S. Jorstad; V. Larionov; A. Marscher; D. Morozova; P. Smith
Saint Petersburg State University, Russia
Email: dernord@gmail.com
We present results of 4 years of multifrequency
observations of 6 FSRQ objects (0420-014, 1156+295, 1222+216, 1633+382,
2230+114) carried out with the Fermi Large Area Telescope (LAT) at gamma-rays ,
with different ground based telescopes in photometric and polarimetric modes at
optical wavelengths, and with the Very Long Baseline Array (VLBA) at 43 GHz. We
have analyzed total and polarized intensity images of the blazars obtained with
the VLBA to study the kinematic evolution and polarization of the pc-scale jets
of the sources. For all sources we have compared flux variations in the VLBI
core and bright superluminal knots with gamma-ray and optical light curves. The
majority of gamma-ray flares coincide with the appearance of a new superluminal
knot as well as with a flare at optical wavelengths and in the millimeter-wave
core. These results support the conclusion that many gamma-ray and optical
flares in blazars originate in the vicinity of the millimeter- wave core or
even downstream the jet.
Particle Acceleration by Magnetic Reconnection and Non-thermal Emission in the Accretion-Disk/Coronae of AGNs
Behrouz Khiali; E. De Gouveia Dal Pino; M.V. Del Valle; G. Kowal; H. Sol
Institute of Astronomy - University of Sao Paulo, Brazil
Email: bkhiali@usp.br
Very high energy observations of AGNs are challenging current theories of particle acceleration (mostly based on shock acceleration) which have to explain how particles are accelerated to energies above TeV in very compact regions compared to the characteristic scales of their sources. The identification of AGNs as sites of particle acceleration raises many fascinating and important questions. Recent magneto-hydrodynamical studies have revealed that cosmic ray acceleration by fast magnetic reconnection can be rather efficient because a first-order Fermi process may occur. In this work, we discuss this acceleration mechanism in the coronal region of the accretion disk around AGNs. In addition, the accelerated particles lose substantial amounts of their energy due to non-thermal interactions with the surrounding magnetic field, matter and radiation fields. We will compute the corresponding acceleration rate and the relevant loss rates in order to reproduce the observed high energy spectrum of two AGNs with strong gamma ray emission, Mrk 421 and Mrk 501, considering both leptonic and hadronic processes.
AGN III - primordial
activity in nuclei of late-type galaxies with pseudobulges
Boris Komberg; A. Ermash
Astro Space Centre of Lebedev Physical Inst. of Russian AS, Moscow,
Russia
Email: bkomberg@asc.rssi.ru
1. Based on observational data on evolution of quasars
and galaxies of different types along with the results of numerical simulations
we make a conclusion that on low redshifts (z<0.5) QSOI/II objects in
massive elliptical and spiral galaxies with classical bulges cannot be in late
single activity event (be "primordial"). Instead of it they have
had events of activity earlier in their evolution. It means that their presence
on low redshifts is connected with the recurrence phenomenon, sequential wet
minor mergings, because timescale of the activity does not exceed several units
of 107 years.
The IR emission of
low-luminosity AGN
Rachel Mason
Gemini Observatory, USA
Email: rmason@gemini.edu
Active galactic nuclei (AGN; quasars, Seyfert galaxies
etc.) are perhaps best known as spectacular phenomena that in some cases can
outshine the entire galaxy in which they reside. In fact the duty cycles of AGN
are low, and active galaxies spend most of their time in a near-quiescent,
low-luminosity, weakly-accreting state. At these low accretion rates, the
workings of AGN are predicted to change dramatically. The inner part of the
accretion disk is thought to "inflate" into a geometrically thick,
optically thin structure, and energy and matter become diverted into jets.
Luminous AGN host a torus of dust and gas that obscures the active nucleus from
some directions and governs how we see and interpret these objects. When the
inflow of material to the nucleus is small, some models predict that the torus
can no longer be sustained; it becomes optically thin and eventually
disappears. A full understanding of the physics and life cycles of active
galaxies therefore implies understanding these outwardly unspectacular members
of the class. We present high-resolution infrared observations aimed at testing
hypotheses about the inner workings of low-luminosity AGN, and some recent
results from comparing the observations to ADAF+disk+jet models.
Dependence of
equivalent width of quasar emission lines on UV-optical spectral index
Olena Torbaniuk; G. Ivashchenko
Astron. and Space Physics Dept, Taras Shevchenko Natl Univ. of Kyiv,
Main Astronomical Observatory of NAS,
Ukraine
Email: el.torbaniuk@gmail.com
The spectral energy distribution (SED) of quasars in
UV-optical range is characterised by the Big Blue Bump with a pick around
1000-1300 Å, broad emission lines, broad absorption lines (in ~10%
of objects) and the flux decrement redward of 1215 Å caused by absorption
in the intergalactic medium. Quasar UV-optical SEDs are remarkably similar from
one object to another, the main differences are in spectral index αλ and equivalent width of emission lines.
Continuum and emission lines are believed to originate from the hot accretion
disc and circumnuclear fast moving clumps, correspondingly. The proximity of
these regions is considered to be the most promising explanation of the Baldwin
effect: the inverse correlation of equivalent width of some emission lines with
the monochromatic luminosities at UV region. On the other hand, the physical
explanation of the difference in spectral indices and their dependence on
quasar parameters are still not clear. We
present the analysis of quasar emission lines properties within the wavelength
range 1215-1450 Å and their dependence on quasar luminosity and spectral
index. For this purpose a set of composite spectra is compiled from subsamples
of SDSS DR7 medium resolution quasar spectra with similar αλ at this wavelength range and similar
monochromatic luminosities at 1450 Å (l1450). We consider the
αλ range of -2.3..-0.7, the log(l1450) range of
42.2..43.4, and emission features around Lyα+NV+SiII,
OI+SiII, CII and SiIV+OIV. It is found, that
equivalent width decreases with increase of luminosity (the Baldwin effect) and
also with spectrum steepening. It is worth noting, that the spectral index does
not depend on luminosity and redshift, but due to selection effects of optical
survey subsamples of higher luminosity have higher redshift.
Halo Occupation
Distribution of AGNs through Numerical Simulations
Liliana Altamirano; T. Miyaji; H. Aceves
Instituto de Astronomia - Universidad Autonoma Nacional de Mexico,
Mexico
Email: lili@astrosen.unam.mx
Recent AGN clustering and Halo Occupation Distribution
(HOD) studies show that moderate luminosity X-ray selected AGNs are hosted by
dark matter halos in the mass log MDMHMΘh-1 = 12.75 and the number of AGNs per halo N(MDMH) stays flat above this minimum mass.
This is in contrast with the HOD results of general galaxy population, where N(MDMH) grows proportionally to MDMH. By means of cosmological LCDM simulations, we test whether we can reproduce the flat HOD of AGNs under the assumption that they are triggered by major mergers. Preliminary results show that the major merger triggering do not reproduce the flat HOD of AGNs and probably mechanisms other than major mergers
are responsible for triggering these AGNs. We also plan to test other
triggering mechanisms such, minor mergers, fly-by encounters and random
triggerings.
AGN populations in
compact groups of galaxies
Arthur S. Amirkhanian;
A.G. Egikian; A. del Olmo; H. Tiersch; D. Stoll; H. Perea
Byurakan Astrophysical Observatory (BAO), Armenia
Email: anegik@mail.ru
Compact groups of galaxies have revealed some
interesting problems from their origin and lifetime to the evolution of their
members in such dense configurations. Some authors suppose that compact groups
of galaxies probably will be the best location for AGNs in the local Universe.
According our preliminary data about 7-10% of member galaxies in Shahbazian
compact groups are the emission-line galaxies including the broad-line AGNs (of
classical Seyfert 1 type) and the narrow emission-line galaxies. Their redshift
makes these galaxies a physical member of the host group. Shahbazian 355/4 is a
classical Seyfert 1 galaxy (discovered by our research group) at the same
redshift as host group. Moreover Shahbazian 278/4 is also the broad-line AGN in
an early-type galaxy. This is the first emission-line object in Shahbazian
compact groups (discovered by Spanish astronomers). Meanwhile there is no
Seyfert 1 galaxy among the spectroscopically investigated (by Brazilian astronomers et al.) galaxies in the South compact groups,
although more than 70% of the member galaxies in these groups probably have an
active nucleus. Why? The UZC- compact groups have an excess of Seyfert 2s (but
not Seyfert 1s!). Why? Further observational studies are necessary to
understand such and many other questions related with the puzzle of compact
groups.
The links between SNe
frequencies and activity level of host galaxies
Levon Aramyan; A.A. Hakobyan; V.Zh. Adibekyan; A.R. Petrosian; L.S. Aramyan; G.A. Mamon;
D. Kunth; V. de Lapparent; E. Bertin; J.M. Gomes; M. Turatto
Byurakan Astrophysical Observatory (BAO), Armenia
Email: aramyan@bao.sci.am
In this work, we investigate how the nuclear activity
is connected with enhanced star formation activity and production of different
types of supernovae (SNe) in galaxies. We perform a statistical study of SNe
discovered in galaxies with different activity levels of nucleus (e.g.,
passive, star-forming, low-ionization nuclear emission-line region (LINER), or
Seyfert), using number ratios of various SN types (e.g., NIbc/NII, NIc/NIb, and
NIa/NCC). With the aim of assessing the effects of bars on SNe frequencies, we
also present an analysis of host properties and SNe frequencies in galaxies
with and without bars. Furthermore, we use large sample of SNe in host galaxies
within interacting and/or merging systems, to explore the frequencies of
different types of SNe resulting from star formation in both disturbed and
undisturbed host galaxies.
The distribution of
SNe in AGN host galaxies
Levon Aramyan; A.A. Hakobyan; V.Zh. Adibekyan; A.R. Petrosian; L.S. Aramyan; G.A. Mamon;
D. Kunth; V. de Lapparent; E. Bertin; J.M. Gomes; M. Turatto
Byurakan Astrophysical Observatory (BAO), Armenia
Email: aramyan@bao.sci.am
We compare the normalized radial distribution of
core-collapse (CC) supernovae (SNe) in nearby spiral disks with active galactic
nuclei (AGN) host galaxies and star-forming galaxies.
A subsample of SNe with available position measurements is selected from
Hakobyan et al. (2012) database requiring available SDSS spectroscopy data of
their host galaxies. Both directly measured number distributions and surface
density distributions indicate that the SNe detected in star-forming galaxies
follow an exponential law, in contrast, the SNe detected in AGN host galaxies
significantly deviate from an exponential law, which is independent of both
morphological type and redshift. This result provides an evidence that young
stellar disks in AGN host galaxies are disturbed and deviate from exponential
distribution structure, due to influence of active nucleus.
No galaxy overdensity
around a QSO at z=5.7
Eduardo Banados; B. Venemans; F. Walter; J. Kurk; R. Overzier; M. Ouchi
Max Planck Institute for Astronomy, Germany
Email: banados@mpia.de
High-redshift quasars are believed to reside in the
most massive halos in the early Universe and should therefore be located in
fields with overdensities of galaxies, which are thought to evolve into galaxy
clusters seen in the local Universe. However, despite many efforts, no
unambiguous relation between galaxy overdensities and z ~ 6 quasars has
been found, which can possibly be attributed to the difficulty of finding
galaxies with accurate redshifts in the quasars' vicinity. So far, overdensity
searches around z ~ 6 quasars are based on studies of continuum dropout
galaxies, which probe a redshift range of Δz ≈ 1. This range is
large enough to select galaxies which may not be physically related to the
quasar. In this study, we use deep narrow-band imaging
to study the environment of the z=5.72 quasar ULAS J0203+0012. The redshift
range probed by our narrow band selection is Δz ≈ 0.1,
significantly narrower than continuum dropout searches. This is the first time
that Lyman alpha emitters (LAEs) are searched for near a z ~ 6 quasar, to
provide clues on the surroundings of quasars at the end of the epoch of
reionization. The main result of this work is that no enhancement of LAEs has
been found in the surroundings of ULAS J0203+0012,
several explanations and interpretations are discussed.
Host galaxy properties
of radio selected AGN
Margherita Bonzini; P. Padovani; V. Mainieri; K. Kellermann; N. Miller; P. Rosati; P. Tozzi; Sh. Vattakunnel
ESO, Germany
Email: mbonzini@eso.org
Deep radio surveys are an important tool to
investigate the evolution of star forming galaxies (SFG) and active galactic
nuclei (AGN), since the radio band is much less affected by dust extinction as
compared to the optical and soft X-ray frequencies. We are studying a sample of ~900 radio
sources detected at 1.4 GHz in a VLA survey of the Extended Chandra Deep Field
South (E-CDFS) down to ~30μJy. Thanks to the wealth of data available
in this field, we use a multi-wavelength approach to differentiate AGN from SFG
using their mid-infrared to radio flux density ratios, their IRAC colors, and
their X-ray powers. The μJy sensitivity of our survey allows us to explore
the faint end of the radio population and to detect not only radio loud AGN,
but also a significant population of radio quiet objects. We compare the host
galaxy properties (stellar masses, optical colors, and morphology) for these
radio selected sources. Based on
our analysis, the radio emission detected in the radio-quiet AGN is produced by
star-formation activity rather than accretion on the central black hole. We
have therefore the remarkable opportunity to use the radio emission itself to
estimate the star-formation level in the host galaxy and compare it to the star
formation rate derived from Herschel observations. Our characterization of the
faint radio sky is very relevant for the upcoming radio surveys, which will be
soon generated by the Square Kilometre Array (SKA) and its pathfinders.
The starburst-AGN
connection on ~100 pc scales in nearby Seyfert galaxies
Pilar Esquej; A. Alonso-Herrero
Centro de Astrobiologia, Spain
Email: pilar.esquej@cab.inta-csic.es
Several works have shown that there is an empirical
correlation between the star formation rate (SFR) and the AGN luminosity (and
thus the black hole accretion rate, BHAR) of Seyfert galaxies. This suggests a
physical relation between the gas forming stars on kpc scales and the gas on
sub-pc scales that is feeding the black hole. Numerical simulations predict
this relation and also that the correlation should be more prominent on smaller
physical scales. However, dynamical delays between the peaks of the star
formation and the black hole growth which depend on the physical scales in the
galaxy are also predicted. We have compiled high angular resolution (0.4-0.8
arcsec) mid-infrared spectroscopy obtained with T-ReCS, VISIR, and Michelle of
26 Seyferts in the Shapley-Ames sample, which allows us to probe physical
regions on scales of ~100 pc. We use the 11.3 μm PAH feature to probe the star formation activity in the inner ~100 pc
of these galaxies, and its relation with the BHAR on these physical scales.
Future planned observations with the mid-IR CanariCam instrument will allow a
similar study for larger samples of Seyfert galaxies.
The NLR Size - IR
Luminosity Relationship: An Upper Limit on the Size of the NarrowLine Region?
Kevin Hainline; R. Hickox; J. Greene; A. Myers; N. Zakamska
Dartmouth College, USA
Email: kevin.n.hainline@dartmouth.edu
We examine the spatial extent of the narrow-line
regions (NLRs) of a large sample of local active galaxies. While we see a
shallow slope in the relationship between NLR size and [OIII] luminosity
(L[OIII]), we also explore how the NLR size scales with a more direct measure
of instantaneous AGN power using mid-IR photometry from WISE. IR emission
probes warm to hot dust near the central black hole and so, unlike L[OIII], it does not depend on the properties of the NLR. We
calculate a power-law relationship between NLR size and 8 micron luminosity
(L8μm) that is significantly steeper than
that observed for NLR size and L[OIII]. We find that the size of the NLR goes
approximately as L8μm1/2, as expected from
the simple scenario of constant-density clouds illuminated by a central
ionizing source. We further see tentative evidence for a turnover at the high
luminosity end of the relationship between NLR size and L8μm, and propose that we are seeing a limiting NLR size of 10 - 20 kpc, beyond which the availability of gas to ionize becomes too
low. We find that L[OIII] is proportional to
L8μm1.4, consistent with a picture in which the [OIII] luminosity
is dependent on the volume of the NLR. Together, these results indicate that
high-luminosity quasars have a strong effect in ionizing the available gas
throughout their host galaxies.
Evidence of AGN-driven
Outflows in Young Radio Quasars selected from the Wide-Field Infrared Survey
Explorer
Minjin Kim; L. Ho; C. Lonsdale; M. Lacy; A. Blain; A. Kimball
Carnegie Observatories, USA
Email: mjkim@obs.carnegiescience.edu
We present near-infrared spectra of young radio quasars
selected by cross-correlating the Wide-Field Infrared Survey Explorer (WISE)
all-sky survey catalog with the radio catalog [Faint Images of the Radio Sky at
Twenty cm (FIRST) and NRAO VLA Sky Survey (NVSS)] .
The detected objects have typical redshifts of z ≈ 2 and [OIII]
luminosities of 1047 erg s-1 comparable to
those of luminous quasars. Based on the intensity ratios of narrow emission
lines, we find that these objects are likely to be powered by active galactic
nuclei (AGNs). Using the observed [O III] luminosities and rest-frame J-band
magnitudes, we find that the black hole masses are ~ 109.5
MΘ. The [O III] line is exceptionally broad, with full width at half
maximum ~ 1300 to 2100 km s-1, significantly
larger than that of ordinary distant quasars. We argue that these large line
widths can be explained by jet-induced outflows.
IGM Heating and AGN
activity in fossil galaxy groups
Halime Miraghaei; H. Khosroshahi; H. Klockner; N. Jetha; S. Raychaudhury; T. Ponman
Sharif
University of Technology, Iran
Email: h.miraghaee@gmail.com
Fossil galaxy groups famed to have undisturbed inter-galactic gas due to lack of recent group scale
mergers are energetically and morphologically ideal environments to study the IGM heating. In this
work we study the role of active galactic nuclei in heating the IGM in a sample of five known fossil
galaxy groups by employing their GMRT observations at 610 MHz and 1.4 GHz. We find that only
two of the dominant galaxies in fossil groups are associated with the radio lobes. We evaluate the PV
work of the radio lobes and their corresponding heating power and compare to the X-ray emission loss
within cooling radius. Our results show that the power due to mechanical heating is not sufficiently
high to suppress the cooling.
Close environments of supernovae host galaxies
Tigran A. Nazaryan; A.R. Petrosian; A.A. Hakobyan; V.Zh. Adibekyan; D. Kunth; G.A. Mamon;
M. Turatto; L.S. Aramyan
Byurakan Astrophysical Observatory (BAO), Armenia
Email: nazaryan@bao.sci.am
We used 56 supernovae (SNe) located in pairs of galaxies to investigate the influence of the properties of their hosts and close environment on star formation (SF) and nuclear activity. The statistical study of SN hosts shows that there is no significant difference between morphologies of hosts in our sample and larger general sample of SN hosts in the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). Average distances of core collapse (CC) SNe from nuclei of hosts are consistent with previous results compiled with larger sample. Surface densities of CC SNe in spiral hosts are not described by exponential fall in contrast with that in isolated galaxies. For the first time it is shown that SNe Ibc are located in pairs with smaller difference of radial velocities between components than pairs containing SNe Ia and II. We consider this as a result of higher star formation rate (SFR) in SNe Ibc hosts. Luminosity ratio of host and neighbor galaxies in pairs does not show any correlation with SNe types. The orientation of SNe with respect to the preferred direction toward neighbor galaxy is found to be isotropic and independent of kinematical properties of galaxy pair.
Multiwavelength Study of Radio Loud Early Type Galaxies from B2 Sample
Sheetal Kumar Sahu; L. Chaware; S.K. Pandey; S. Kulkarni; N.K. Chakradhari
Pt. Ravishankar Shukla University Raipur, India
Email: sks.1884@gmail.com
We present multiwavelength study of a sample of radio loud early type galaxies chosen from B2 sample. We performed surface photometry in 'BVR' broad band filter and Hα narrow band filter on CCD images of sample galaxies using IGO 2m telescope, Pune(INDIA), to get radial profiles of various photometric and geometrical parameters that describe elliptical isophotes fitted to the 2D light distribution of the galaxies. The analysis of radial profiles of quantities such as the (local) surface brightness, the ellipticity, and the deviations from elliptical isophotes parametrized by the Fourier coefficients are main focus of our study. We generated color maps, residual maps, and dust extinction maps, Hα emission maps of the galaxies to study the morphology of the dust and ionized gas content present in the galaxies. We carried out detailed analysis of the dust properties for sample galaxies. We made use of the HST(WFPC2) archival optical images to investigate properties of the dust in the central region(~10 arcsec) of our sample galaxies. We also estimated mass and temperature of the dust, molecular gas mass, mass loss by red giant stars and mass loss rate from evolved stars in the sample galaxies using FIR fluxes of the galaxies obtained from IRAS.
We used spectroscopic archival data from SDSS (DR7) to get an estimate of the mass of the central super massive black-hole, SFR, and metallicites for the sample galaxies. The multi-wavelength study of our sample galaxies enabled us to address wide variety of issues related to origin, nature and fate of dust in radio-loud early type galaxies, coexistence of multiphase ISM in extra-galactic environment, and possible implications for the scenarios of galaxy formation and evolution. The results are presented in this poster.
Probing Quasar Host
Galaxy Evolution Through Their Narrow-Line Regions
Aycha Tammour; S. Gallagher
University of Western Ontario, Canada
Email: atammour@uwo.ca
Though quasar spectra in general are remarkably
similar over a wide range of redshift and luminosity, systematic trends in
emission-line properties such as the Baldwin Effect and the eigenvector 1
correlations are well-known. However, their link to the physical properties of
the accretion disk and black hole are not yet fleshed out. The eigenvector 1
correlations linking broad-emission line properties such as the width of
Hβ and the strength of [OIII] are particularly puzzling given the huge
differences in physical scale of the emitting regions. The narrow-line region
(NLR) in particular - on kpc scales - is revealing the host galaxy ISM rather
than the immediate vicinity of the central engine. Our goal is to separate the
properties of the central engine - probed by properties such as continuum
luminosity and the broad Hβ emission line - from the properties of the
NLR. We construct and analyze quasar composite spectra made using optical
spectra from the Sloan Digital Sky Survey-Data Release 7 quasar catalogue in
order to study the evolution of the NLR with redshift. For each one of our
composites, we focus on lines with ionization potentials ranging from 14 to 130
eV in order to probe regions of the NLR at a range of distances from the
central source. We divided the sample into high and low continuum luminosity
bins, and further divided each of these subsamples by their Hβ widths.
We study each of these four groups of high/Low L5100
- broad/narrow Hβ at 5 steps of redshift up to z < 0.75 to constrain
the host galaxy ISM on NLR scales.
Study of
Starburst/Activity/Interaction Phenomena based on the Multiple ByurakanIRAS
Galaxies
Gohar Harutyunyan; A.M. Mickaelian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: goharutyunyan@gmail.com
The Byurakan-IRAS Galaxy (BIG) sample is the result of
optical identifications of IRAS PSC sources at high-galactic latitudes using
the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1278 objects
most are spiral galaxies and many have been proved to be AGN and starburst by
spectroscopic observations, as well as there is a number of ULIRGs among these
objects. BIG objects contain galaxy pairs, multiples, and small groups that are
subject for study on the matter of the real IR-emitter in these systems. Given
that these objects are powerful IR sources, they are considered as young
systems indicating high rate of evolution and starburst activity exceeding 100
M_sun/yr. Spectroscopic observations show that all these systems are physical
ones and we were able to measure the mutual distances and sizes for all
components. Cross-correlations with the recent more accurate IR catalogues,
such as 2MASS, WISE and AKARI, as well as radio ones (NVSS, FIRST), provided
accurate coordinates of the IR sources and possibility to find the individual
galaxy responsible for the IR. However, in almost half of the cases, IR
position indicates the intermediate regions between the components, which means that it comes from the system as a whole. Some more MW
data have been matched to IR and radio to have an overall understanding on
these systems of galaxies. Given that these systems are mostly
interacting/merging ones often containing AGN and most of them may be
considered as powerful starbursts, it is possible to study starburst/activity/interaction
phenomena and their interrelationship.
Bipolar outflow from magnetized accretion disk in radio galaxy М87
Martin Abrahamyan; L.I. Matveyenko
Yerevan State University, Armenia
Email: mabr4913@gmail.com
The superfine structure of the jet formation region in the radio galaxy М87 has been investigated. The high-velocity bipolar outflow is ejected from the central disk region, a nozzle 4 mpc in diameter, while the low-velocity one is ejected from a ring 60 mpc in diameter and 14 mpc in width. The low-velocity plasma flow is a hollow tube with a built-in helix. The components of the structure, its disk and bipolar outflow, suggest solid-body rotation. The hydro-magnetic theory of bipolar outflow from an accretion disc with a thyroidal magnetic field is constructed and compared with the observations.
Hour-timescale profile
variations in the broad Balmer lines of the Seyfert galaxy Markarian 6
Norayr Asatrian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: asat@bao.sci.am
Results of the multi-epoch intranight optical
spectroscopic monitoring of the Markarian 6 nucleus carried out at the
telescopes of 6-m of the Special Astrophysical Observatory (Russia) and 2.6-m
of the Byurakan Astrophysical Observatory (Armenia) are presented. Observations
were made in 1986, 1988-1991 and 2007-2009 during a total of 33 nights with an
average sampling rate of 4 spectra per night. There were used TV-scanner and
long-slit spectrographs equipped with Image Tube and CCD detector arrays.
Altogether 110 Hbeta and 58 Halpha region spectra were analyzed to search for
intranight variability in the broad hydrogen emission line profiles. The
typical spectral resolutions were 4A for scanner spectra, 6A for photographic
spectra, 5A and 10A for CCD spectra. The signal-to-noise ratio at the continuum
level near the Hβ and Hα lines was
in range 15-50. The purpose of the search was to look for the characteristic
variability signatures of different kinematical models of the broad
emission-line region. We considered the centering and guiding errors which can
result in differences between spectra. We
found variations in the broad Balmer line difference profiles on time scale of
hour with the level of significance of 3.6sigma to 9.0sigma. Variations take
the form of narrow, small bumps in the difference spectrum. Difference profiles
displayed two kinds of variability patterns: one-sided (blue side) variability
pattern and two-sided variability pattern (changes occur simultaneously at the
blue and red sides of line profile). None of difference spectra shows any
evidence for bumps drifting across the line profile. In the intermediate level
of broad line flux, the Hbeta profile shows clear fine structure. Detected
profile changes occurred at the same radial velocity shifts as the details in
the fine structure within the spectral resolution. The variability is at
least 2 orders of magnitude more rapid than any observed for broad Balmer line
profiles in AGNs that we are aware of in the literature. Discovered extremely rapid
line-profile variability may be associated with reverberation effects. Observed
profile changes may indicate the response of circularly rotating hydrogen
clouds in the BLR with a macroturbulence to a light pulse from a central
source. Alternatively, one-sided profile variations may be attributed to a
response of a non-disk component: the subarcsec-scale region of the jet.
Black hole mass and
BLR size at high redshift
Ismael Botti; P. Lira; Sh. Kaspi; H. Netzer
School of Physics & Astronomy, University of Nottingham, United
Kingdom
Email: ppxib1@nottingham.ac.uk
Reverberation mapping (RM) is the only tool to
directly measure the broad-line region (BLR) size and black hole mass in AGN in
the distant Universe and it has been applied, so far, only to small and
intermediate systems (L<1046 erg s-1). Moreover, single-epoch black hole mass
estimators in AGN at high redshift rely on the validity of the empirical
relation between the BLR size and luminosity which has to be extrapolated to
high luminosity by even two orders of magnitude. Currently, several efforts to
populate its high luminosity end are underway, however, the long time scales
and low amplitude variability involved make of this a challenging task with yet
no significant results. We will present preliminary results of a monitoring
campaign of a sizable sample of high luminosity quasars at z~2-3 which
has gathered, so far, ~7 years of data that will allow us to fill the
high luminosity end of the BLR size-luminosity relation and measure masses of
the largest black holes, extending our knowledge of this crucial epoch in
galaxy evolution.
Selected Results of
Panoramic Spectroscopy of Some FBS Galaxies
Susanna Hakopian; S. Balayan; T. Movsesyan
Byurakan
Astrophysical Observatory (BAO), Armenia
Email: sanna@web.am
Panoramic spectroscopy of some of the close Markarian galaxies (z < 0.03),
differing in a complex morphology, was carried out by us from the
observations with the 2.6 m telescope of Byurakan Observatory using
multipupil spectrograph “VAGR”. The obtained data refer mainly to the
emission of the studied galaxies in the balmer line of hydrogen Ha.
Hardening of the X-ray
spectrum and signature of Fe abundance in Mrk 501 based on the filamentary jet
model
Yasuko S. Honda; M. Honda
Kinki University Technical College, Japan
Email: honda@tse.kutc.ac.jp
Markarian 501 has
been well-studied by many researchers as a typical TeV blazar having broadband
radiation spectrum with double-humped appearance. In particular, its prominent
flaring in 1997 April was remarkable and numerous studies were devoted to
explain the spectral change. Most of the spectral fittings were produced by the
broken power-law based on the homogeneous synchrotron self Compton (SSC) model.
In this model, the internal emitting region is presumed to be almost
homogeneous and the energy peak of the spectrum around radio to X-ray is
dominated by synchrotron radiation of accelerated electrons. Provided that the
synchrotron cooling is taking place in a simple uniformly filled jet, however,
X-ray photons will be overproduced compared to the observed fluxes. Such
deficit of radiation implies the presence of substructure in the internal jet.
Moreover, the update satellite observations indicate that the spectrum has no
steep cutoff but extends to X-ray band, far beyond the theoretical upper limit
derived by the conventional diffusive shock acceleration (DSA) mechanism.
In this paper, we attempt to reproduce the
radiation spectrum of Mrk 501 in the X-ray region based on our filamentary jet
model. This model was originally proposed in order to explain the collimation
of active galactic nuclei (AGN) jets over the long range [1]. When the
energetic plasma flow is injected from a central engine, huge currents are
generated due to the inertia difference of positive and negative particles only
if a small fraction of protons or nuclei are contained in plasma constituents. Because of the electromagnetic current filament
instabilities, these currents break up into numerous filaments
with self-induced toroidal magnetic fields. These randomly oriented local
fields are cancelled in the inside of the jet except large scale toroidal
fields along the envelope. Such configuration is in good accordance with
polarization measurements [2]. When a shock wave is allowed to propagate in AGN
jets with such magnetized filaments, the magnetic field inclination to the
shock normal is likely to be quasi-perpendicular. Then, cosmic ray particles in
situ can be efficiently energized [3]. Suppose a jet as a bunch of numerous
magnetized filaments with various transverse sizes. Since the size distribution
of filaments is still unknown, we assume the homogeneous distribution in the
range between sufficiently larger than the order of skin depth and the jet
diameter. As a consequence of kinetic simulations that the amplification of
magnetic fields accompanies the coalescence of filaments, we have considered a
situation in which the larger filaments sustain stronger magnetic field. We
then use the power-law scaling of the magnetic field with respect to the
transverse filament sizes. In low plasma beta state, electrons are strictly
bound to the local magnetic field induced by each filament. If these electrons
are passing through the above-mentioned quasi-perpendicular shock, they are
efficiently accelerated. The attainable maximum energies of accelerated
electrons are determined by the competition of synchrotron cooling and escape
from individual filament. Both processes of acceleration and cooling strongly
depend on the local magnetic field, and hence, the transverse size of each
filament. Based on these assumption, electrons with
various energies are produced by the acceleration and cooling due to different
magnetic fields induced by different sizes of filaments. The spectrum in the
X-ray region can be accounted for the superposition of synchrotron radiation
spectra from these magnetic fields. We
focused on mainly three parameters related to the magnetic fields, the field
strength of the largest filament, field fluctuation, and turbulent spectral
index. The field strength directly affects on the absolute value of flux mainly
in lower frequencies. On the other hand, as the field fluctuation becomes
larger, the fluxes are enhanced around peak frequencies. The turbulent spectral
index changes both the absolute fuxes and spectral exponents in the X-ray
region significantly. Since the larger value of index reflects the degree of
turbulent evolution, the change of index corresponds to the time evolution of spectrum. Parametrizing these variables in the
conceivable range, we evaluate the spectrum around X-rays. Then, we compare our
calculated spectrum with the X-ray fluxes by BeppoSAX satellite observations
between April in 1997 and 1999 including a phase of high activity at TeV
energies [4]. The result shows that the flaring state can be most plausibly
characterized by the the turbulent spectral index, which is related to the
development of turbulence. Comparing the theoretical spectrum with the
observations in detail, we noticed a small dip around 80 keV throughout the
observational term. The spectral shape of the dip is in good accordance with
the bound-free absorption of synchrotron photons by the K-shell electrons of
somewhat heavy ions. The energy around the dip can be accounted for the
Doppler-shifted bound-free absorption of Fe-ions since the ionization potential
of Fe 24+ is corresponding to be 8.8 keV. This suggests a signature of Fe
abundance in the emission region of a blazar jet.
The MASIV Legacy:
Surveying AGN intraday-variability at radio wavelengths
Jun Yi Koay; J. Macquart; B. Rickett; H. Bignall; D. Jauncey; T. Pursimo; C. Reynolds; J. Lovell; L. Kedziora-Chudczer; R. Ojha
Dark Cosmology Centre, University of Copenhagen, Denmark
Email: kjy_nivek@yahoo.co.uk
Following from the Micro-arcsecond
Scintillation-Induced Variability (MASIV) Survey and its follow-up
observations, we now have large datasets of AGN intra-day variability (IDV) at
radio wavelengths. These data have shown that IDV arises mainly from
scintillation caused by scattering in the ionized interstellar medium (ISM) of
our Galaxy, based on correlation with Galactic latitudes and line-of-sight
Galactic electron column densities. The sensitivity of interstellar
scintillation (ISS) towards source angular size has provided a new tool for
studying the most compact components of AGNs at microarcsecond (muas) scale
resolution - much higher than any ground-based radio interferometer. We present
recent results from the MASIV Survey and its follow-up observations, where we
investigated the observed decrease in the ISS of blazars at high redshift (z
> 2). This redshift dependence of blazar ISS requires their muas structures
to be less compact at z > 2, due either to larger angular sizes or decreased
core dominances (flux densities relative to their more extended emission). We
determined that this redshift dependence of ISS is associated with (i) a
cosmological decrease in brightness temperature with redshift in a flux-limited
sample of sources, and (ii) a spectral index-redshift relation coupled with
reduced ISS in sources with steeper spectra. The latter can be a result of
selection effects or blazar evolution. We also discuss other unresolved
questions that we seek to address in future planned observations, including the
origin of the intermittency of AGN IDV. This intermittency can result from
intrinsic changes in muas AGN structures on timescales of weeks/months, the
presence of discrete turbulent structures in the ISM of our Galaxy, or both.
FeLoBAL Outflow
Variability Constraints from Multi-Year Observations
Sean McGraw; J. Shields; F. Hamann; D. Capellupo; S. Gallagher; N. Brandt
Ohio University, USA
Email: sm324510@ohio.edu
The physical properties and dynamical behavior of
Broad Absorption Line (BAL) quasars are crucial themes in understanding the
connections between galactic centers and their hosts. FeLoBALs (identified with
the presence of low-ionization Fe II BALs) are a peculiar class of quasar
outflows that constitute ~ 1% of the BAL population. With their large
column densities and kinetic energy yields, FeLoBALs appear to be exceptionally
powerful and are strong candidates for feedback to galaxy evolution. They are
also common in dust-reddened quasars still closely associated with the
starburst phase in young and very luminous host galaxies. We conducted
variability studies on 12 FeLoBALs within emission redshifts 0.69 ≤ z
≤ 1.93 using up to 5 observation epochs on a given object, spanning both short
(down to ~ 10.3 days) and long (up to
~ 7.03 years) timescales in the quasar's rest frame. Our goals are to
understand the mechanisms producing the variability (e.g. ionization changes or
outflow clouds traversing our line of sight) and place new constraints on the
locations, structure, and kinetic energies of the outflows. The sample included
spectra obtained using the MDM 2.4m Hiltner telescope at Kitt Peak, AZ, along
with data from the 9.2m HET telescope at McDonald Observatory and SDSS data
release 7. New spectra will be combined with Chandra observations on 2 FeLoBALs
in order to further constrain the physical conditions of the gas. Results will
be presented on the nature and characteristics of observed variability for
the sample.
The Role of Radio Loud
Phase of Nuclear Activity in Galaxy Formation and Evolution
Gabriel Ohanian
Byurakan Astrophysical Observatory (BAO), Armenia
Email: gohanian@bao.sci.am
A key question, which arise when clear up a problem of formation and evolution of galaxies, is
question of energy: which is an energetic budget of AGN owing to form galaxies
and provide its subsequent development? Hence, for understanding the formation
and evolution of galaxies, it is important to estimate the energetic budget of
AGN which we try to do involving radio loud phase of nuclear activity. We
collect literature data from the radio to the gamma ray to create a multi
wavelength data base. The analysis of combined data allow
us to find some agreements between theories and observations.