Active Galaxies NewsletterAn electronic publication dedicated to the observations and theory of active galaxies
Edited by Megan Argo
The Active Galaxies Newsletter is an electronic publication dedicated to the observation and theory of active galaxies. It is intended to be used to notify others in the field of recently accepted papers, conference proceedings and dissertations, and also contains announcements of jobs and conferences. It is produced monthly and sent to over 600 subscribers.
The Latex macros for submitting contributions of all sorts is available here and are also appended to each issue of the newsletter. The editor may reject submissions which do not use the template.
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|Active||An electronic publication dedicated to|
|Galaxies||the observation and theory of|
|No. 215 -- September 2015||Editor: Megan Argo (firstname.lastname@example.org)|
Jobs Adverts - Meetings Adverts - Special Announcements
Welcome to all the new subscribers, and thanks to everyone who contributed to this issue of the Active Galaxies Newsletter. This newsletter is intended to disseminate paper abstracts, meeting announcements, job adverts and other information which may be of interest to the active galaxies community. It is produced monthly and, whilst the deadline for contributions is the last day of the month, contributions may be submitted at any time.
The Latex macros for submitting abstracts and dissertation abstracts are appended to each issue of the newsletter and are also available on the web page. Please note that the editor may reject submissions which do not use the template. As always, any suggestions or feedback regarding the newsletter are welcome.
Thanks for your continued subscription.
Discovery of a Highly Polarized Optical Microflare in the Blazar S50716+714 During 2014 WEBT Campaign
Gopal Bhatta1, Arti Goyal1 and Michał Ostrowski1 (and 42 other authors)
1. Astronomical Observatory of Jagiellonian University, ul. Orla 171, 30-244 Krakow, Poland
The occurrence of low-amplitude flux variations in blazars on hourly timescales, commonly known as microvariability, is still a widely debated subject in high-energy astrophysics. Several competing scenarios have been proposed to explain such occurrences, including various jet plasma instabilities leading to the formation of shocks, magnetic reconnection sites, and turbulence. In this letter we present the results of our detailed investigation of a prominent, five-hour-long optical microflare detected during recent WEBT campaign in 2014, March 2-6 targeting the blazar 0716+714. After separating the flaring component from the underlying base emission continuum of the blazar, we find that the microflare is highly polarized, with the polarization degree ∼(40-60)% ± (2-10)%, and the electric vector position angle ∼(10-20)deg ± (1-8)deg slightly misaligned with respect to the position angle of the radio jet. The microflare evolution in the (Q, U) Stokes parameter space exhibits a looping behavior with a counter-clockwise rotation, meaning polarization degree decreasing with the flux (but higher in the flux decaying phase), and approximately stable polarization angle. The overall very high polarization degree of the flare, its symmetric flux rise and decay profiles, and also its structured evolution in the Q-U plane, all imply that the observed flux variation corresponds to a single emission region characterized by a highly ordered magnetic field. As discussed in the paper, a small-scale but strong shock propagating within the outflow, and compressing a disordered magnetic field component, provides a natural, though not unique, interpretation of our findings.
Accepted by ApJ Letters
E-mail contact: email@example.com
Preprint available at http://arxiv.org/abs/1507.08424
An evolutionary missing link? A modest-mass early-type galaxy hosting an over-sized nuclear black hole
Jacco Th. van Loon1 and Anne E. Sansom2
1. Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK
2. Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
SAGE1CJ053634.78-722658.5 is a galaxy at redshift z=0.14, discovered
behind the Large Magellanic Cloud in the Spitzer Space Telescope "Surveying the Agents of Galaxy Evolution" Spectroscopy survey (SAGE-Spec).
It has very strong silicate emission at 10 μm but negligible far-IR and UV
emission. This makes it a candidate for a bare AGN source in the IR, perhaps
seen pole-on, without significant IR emission from the host galaxy. In this
paper we present optical spectra taken with the Southern African Large
Telescope (SALT) to investigate the nature of the underlying host galaxy and
its AGN. We find broad Hα emission characteristic of an AGN, plus
absorption lines associated with a mature stellar population (>9 Gyr), and
refine its redshift determination to z=0.1428±0.0001. There is no evidence
for any emission lines associated with star formation. This remarkable object
exemplifies the need for separating the emission from any AGN from that of the
host galaxy when employing infrared diagnostic diagrams. We estimate the black
hole mass, MBH=3.5±0.8×108 M⊙, host galaxy mass,
1.2 ×1010 M⊙, and accretion luminosity, Lbol(AGN)=5.3±0.4×1045 erg s-1 (≈12 per cent of the Eddington luminosity) and find the AGN to be more prominent than expected for a host galaxy of this modest size. The old age is in tension with the downsizing paradigm in which this galaxy would recently have transformed from a star-forming disc galaxy into an early-type, passively evolving galaxy.
Accepted by MNRAS
E-mail contact: firstname.lastname@example.org
Preprint available at http://adsabs.harvard.edu/abs/2015arXiv150800698V
The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines
Mouyuan Sun1,2, Jonathan R. Trump1,14, Yue Shen4,5,14, W. N. Brandt1,3, Kyle Dawson6, Kelly D. Denney7,15, Patrick B. Hall8, Luis C. Ho4,9, Keith Horne10, Linhua Jiang4, Gordon T. Richards11, Donald P. Schneider1, Dmitry Bizyaev12,13, Karen Kinemuchi12, Daniel Oravetz12, Kaike Pan12 and Audrey Simmons12
1. Department of Astronomy & Astrophysics and Institute for Gravitation and the Cosmos, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802, USA
2. Dept. of Astronomy & Institute of Theoretical Physics & Astrophysics, Xiamen University, Xiamen, Fujian 361005, China
3. Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
4. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
5. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101, USA
6. Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112
7. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
8. Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3, Canada
9. Department of Astronomy, School of Physics, Peking University, Beijing 100871, China
10. SUPA Physics/Astronomy, Univ. of St. Andrews, St. Andrews KY16 9SS, Scotland, UK
11. Department of Physics, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, USA
12. Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059, USA
13. Sternberg Astronomical Institute, Moscow State University, Moscow
14. Hubble Fellow
15. NSF Astronomy and Astrophysics Postdoctoral Fellow
We explore the variability of quasars in the MgII and Hβ broad emission lines and UV/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over 6 months, containing 357 quasars with MgII and 41 quasars with Hβ. On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional 2854 quasars with MgII and 572 quasars with Hβ. The MgII emission line is significantly variable (Δ f/f ∼ 10% on ∼100-day timescales), a necessary prerequisite for its use for reverberation mapping studies. The data also confirm that continuum variability increases with timescale and decreases with luminosity, and the continuum light curves are consistent with a damped random-walk model on rest-frame timescales of ≥ 5 days. We compare the emission-line and continuum variability to investigate the structure of the broad-line region. Broad-line variability shows a shallower increase with timescale compared to the continuum emission, demonstrating that the broad-line transfer function is not a δ-function. Hβ is more variable than MgII (roughly by a factor of ∼1.5), suggesting different excitation mechanisms, optical depths and/or geometrical configuration for each emission line. The ensemble spectroscopic variability measurements enabled by the SDSS-RM project have important consequences for future studies of reverberation mapping and black hole mass estimation of 1<z<2 quasars.
Accepted by Astrophysical Journal, 2015
E-mail contact: email@example.com
Preprint available at http://arxiv.org/abs/1506.07886
The Sloan Digital Sky Survey Reverberation Mapping Project: Post-Starburst Signatures in Quasar Host Galaxies at z < 1
Yoshiki Matsuoka1,2, Michael A. Strauss2, Yue Shen3,4,†, William N. Brandt5,6,7, Jenny E. Greene2, Luis C. Ho3,8, Donald P. Schneider5,6, Mouyuan Sun5,6,9, Jonathan R. Trump5,6,†
1. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
2. Princeton University Observatory, Peyton Hall, Princeton, NJ 08544, USA
3. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
4. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101, USA
5. Department of Astronomy & Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
6. Institute for Gravitation & the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA
7. Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
8. Department of Astronomy, School of Physics, Peking University, Beijing 100871, China
9. Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005, China
† Hubble Fellow
Quasar host galaxies are key for understanding the relation between galaxies and the supermassive black holes (SMBHs) at their enters. We present a study of 191 broad-line quasars and their host galaxies at z < 1, using high signal-to-noise ratio (SNR) spectra produced by the Sloan Digital Sky Survey Reverberation Mapping project. Clear detection of stellar absorption lines allows a reliable decomposition of the observed spectra into nuclear and host components, using spectral models of quasar and stellar radiations as well as emission lines from the interstellar medium. We estimate age, mass M*, and velocity dispersion σ* of the host stars, the star formation rate (SFR), quasar luminosity, and SMBH mass M•, for each object. The quasars are preferentially hosted by massive galaxies with M* ∼ 1011 M⊙ characterized by stellar ages around a billion years, which coincides with the transition phase of normal galaxies from the blue cloud to the red sequence. The host galaxies have relatively low SFRs and fall below the main sequence of star-forming galaxies at similar redshifts. These facts suggest that the hosts have experienced an episode of major star formation sometime in the past billion years, which was subsequently quenched or suppressed. The derived M• - σ* and M• - M* relations agree with our past measurements and are consistent with no evolution from the local Universe. The present analysis demonstrates that reliable measurements of stellar properties of quasar host galaxies are possible with high-SNR fiber spectra, which will be acquired in large numbers with future powerful instruments such as the Subaru Prime Focus Spectrograph.
Accepted by Astrophys. J.
E-mail contact: firstname.lastname@example.org
Preprint available at http://arxiv.org/abs/1506.07535
Magnetically Driven Accretion Disk Winds and Ultra-fast Outflows in PG 1211+143
Keigo Fukumura1, Tombesi Francesco2,3, Demosthenes Kazanas2, Chris Shrader2,4, Ehud Behar5 and Ioannis Contopoulos6
1. Physics & Astronomy Department, James Madison University, Harrisonburg, VA 22807, USA
2. ASD, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
3. Department of Astronomy and CRESST, University of Maryland, College Park, MD 20742, USA
4. Universities Space Research Association, 7178 Columbia Gateway Drive Columbia, MD 21046, USA
5. Department of Physics, Technion, Haifa 32000, Israel
6. Research Center for Astronomy, Academy of Athens, Athens 11527, Greece
We present a study of X-ray ionization of magnetohydrodynamic (MHD) accretion-disk winds in an effort to constrain the physics underlying the highly-ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub-classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically-driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an XMM-Newton/EPIC spectrum of the narrow-line Seyfert, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log (ξc [erg cm s-1]) ≃ 5-6 and a column density on the order of NH ≃ 1023 cm-2, outflowing at a characteristic velocity of vc/c ≃ 0.1-0.2 (where c is the speed of light). The best-fit model favors its radial location at rc ≃ 200 Ro (Ro is the black hole innermost stable circular orbit), with an inner wind truncation radius at Rt ≃ 30 Ro. The overall K-shell feature in the data is suggested to be dominated by fexxv with very little contribution from fexxvi and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including PG 1211+143.
Accepted by ApJ., Volume 805, Issue 1, article id. 17, 10 pp. (2015).
E-mail contact: email@example.com
Preprint available at http://arxiv.org/abs/1503.04074
Quasar Classification Using Color and Variability
Christina M. Peters1, Gordon T. Richards1, Adam D. Myers2, Michael A. Strauss3, Kasper B. Schmidt4, Željko Ivezić5, Nicholas P. Ross6, Chelsea L. MacLeod6, Ryan Riegel7
1. Department of Physics, Drexel University, Philadelphia, PA 19104, USA
2. Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA
3. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
4. Department of Physics, University of California, Santa Barbara, CA 93106, USA
5. Astronomy Department, University of Washington, Seattle, WA 98195, USA
6. Institute for Astronomy, The University of Edinburgh, Edinburgh EH9 3HJ, UK
7. Skytree, Inc., 1731 Technology Drive, Suite 700, San Jose, CA 95110, USA.
We conduct a pilot investigation to determine the optimal combination of color and variability information to identify quasars in current and future multi-epoch optical surveys. We use a Bayesian quasar selection algorithm (Richards et al. 2004) to identify 35,820 type 1 quasar candidates in a 239 deg2 field of the Sloan Digital Sky Survey (SDSS) Stripe 82, using a combination of optical photometry and variability. Color analysis is performed on 5-band single- and multi-epoch SDSS optical photometry to a depth of r ∼ 22.4. From these data, variability parameters are calculated by fitting the structure function of each object in each band with a power law model using 10 to >100 observations over timescales from ∼1 day to ∼8 years. Selection was based on a training sample of 13,221 spectroscopically-confirmed type-1 quasars, largely from the SDSS. Using variability alone, colors alone, and combining variability and colors we achieve 91%, 93%, and 97% quasar completeness and 98%, 98%, and 97% efficiency respectively, with particular improvement in the selection of quasars at 2.7<z<3.5 where quasars and stars have similar optical colors. The 22,867 quasar candidates that are not spectroscopically confirmed reach a depth of i∼22.0; 21,876 (95.7%) are dimmer than coadded i-band magnitude of 19.9, the cut off for spectroscopic follow-up for SDSS on Stripe 82. Brighter than 19.9, we find 5.7% more quasar candidates without confirming spectra in sky regions otherwise considered complete. The resulting quasar sample has sufficient purity (and statistically correctable incompleteness) to produce a luminosity function comparable to those determined by spectroscopic investigations. We discuss improvements that can be made to the process in preparation for performing similar photometric selection and science on data from post-SDSS sky surveys.
Accepted by ApJS.
E-mail contact: Christina.M.Peters@drexel.edu
Preprint available at http://arxiv.org/abs/1508.04121
AGN Broad Line Regions Scale with Bolometric Luminosity
1. Department of Physics and Astronomy, Seoul National University, Seoul 151-742, South Korea
The masses of supermassive black holes in active galactic nuclei (AGN) can be derived spectroscopically via virial mass estimators based on selected broad optical/ultraviolet emission lines. These estimates commonly use the line width as a proxy for the gas speed and the monochromatic continuum luminosity, λLλ, as a proxy for the radius of the broad line region. However, if the size of the broad line region scales with the bolometric AGN luminosity rather than λLλ, mass estimates based on different emission lines will show a systematic discrepancy which is a function of the color of the AGN continuum. This has actually been observed in mass estimates based on Hα/Hβ and Civ lines, indicating that AGN broad line regions indeed scale with bolometric luminosity. Given that this effect seems to have been overlooked as yet, currently used single-epoch mass estimates are likely to be biased.
J. Korean Astron. Soc. 48, 203 (2015)
E-mail contact: firstname.lastname@example.org
Open access article: http://jkas.kas.org/journals/2015v48n3/v48n3p203_trippe4.pdf
Restarting radio activity and dust emission in radio-loud broad absorption line quasars
G. Bruni1,2, K.-H. Mack2, F.M. Montenegro-Montes3, M. Brienza4,5, J.I. González-Serrano6
1. Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 Bonn, Germany
2. INAF - Istituto di Radioastronomia, Via P. Gobetti 101, I-40129 Bologna, Italy
3. European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile
4. Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo, The Netherlands
5. Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
6. Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, E-39005 Santander, Spain
Broad absorption line quasars (BAL QSOs) are objects that show absorption from relativistic outflows that have velocities up to 0.2c. In about 15% of quasars, these manifest as absorption troughs on the blue side of UV emission lines, such as CIV and MgII. The launching mechanism and duration of these outflows is not clear yet. In this work, we complement the information collected in the cm band for our previously presented sample of radio loud BAL QSOs (25 objects with redshifts 1.7<z<3.6) with new observations in the m and mm bands. Our aim is to verify the presence of old, extended radio components in the MHz range and probe the emission of dust (linked to star formation) in the mm domain. We observed 5 sources from our sample, that already presented hints of low-frequency emission, with the GMRT at 235 and 610 MHz. Another 17 sources (more than half the sample) were observed with bolometer cameras at IRAM-30m (MAMBO2, 250 GHz) and APEX (LABOCA and SABOCA, 350 and 850 GHz, respectively). All sources observed with the GMRT present extended emission on a scale of tens of kpc. In some cases these measurements allow us to identify a second component in the SED at frequencies below 1.4 GHz, beyond the one already studied in the GHz domain. In the mm band, only one source shows emission clearly ascribable to dust, detached from the synchrotron tail. Upper limits were obtained for the remaining targets. These findings confirm that BAL QSOs can also be present in old radio sources or even in restarting ones where favourable conditions for the outflow launching or acceleration are present. A suggestion that these outflows could be precursors of the jet comes from the possibility that ∼70% of our sample is in a GigaHertz Peaked Spectrum (GPS) or Compact Steep Spectrum (CSS)+GPS phase. This would confirm the idea proposed by other authors that these outflows could be recollimated to form the jet. Compared with previous works in the literature, dust emission seems to be weaker than what is expected in 'normal' QSOs (both radio loud and radio quiet ones), suggesting that a feedback mechanism could inhibit star formation in radio-loud BAL QSOs.
Accepted by A&A
E-mail contact: email@example.com
Preprint available at http://arxiv.org/abs/1507.08533
Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared. Direct evidence for an extended nuclear torus
D. Gratadour1, D. Rouan1, L. Grosset1, A. Boccaletti1 and Y. Clénet1
1. LESIA, Observatoire de Paris - CNRS, UPMC, Université Paris-Didierot
Context. To investigate the central regions of active galactic nuclei (AGN) at short wavelengths, high angular resolution and high contrast observations are mandatory. Aims. One of the main observational challenge is the direct detection of the circumnuclear optically thick material hiding the central core emission when viewed edge-on. The lack of direct evidence is limiting our understanding of AGN and several scenarios have been proposed to cope for the diverse observed aspects of activity in a unified approach. Methods. Observations in the near-infrared spectral range have shown powerful to provide essential hints because of the reduced optical depth of the obscuring material. Moreover, it is possible to trace this material through light scattered from the central engine closest environment, polarimetric observations thus being the ideal tool to disentangle it from purely thermal and stellar emissions. Results. Here we show strong evidence for an extended nuclear torus at the center of NGC 1068 thanks to new adaptive optics assisted polarimetric observations in the near-infrared. The orientation of the polarization vectors clearly evidences the presence of a structured hourglass-shaped bicone and a compact elongated (20 x 60 pc) nuclear structure perpendicular to the bicone axis. The linearly polarized emission in the bicone is dominated by a centro-symmetric pattern, but the central compact region shows a clear deviation from the latter with linear polarization aligned along a direction perpendicular to the bicone axis.
Accepted by Astronomy & Astrophysics
E-mail contact: firstname.lastname@example.org
Preprint available at https://upload.obspm.fr/get?k=J72iv7m3Xp6v82EwO3O
A Variable-Density Absorption Event in NGC 3227 mapped with Suzaku and Swift
T. Beuchert1,2, A.G. Markowitz1,3,4, F. Krauß1,2, G. Miniutti5, A.L. Longinotti6, M. Guainazzi7, I. de La Calle Pérez7, M. Malkan8, M. Elvis9, T. Miyaji10,3, D. Hiriart10, J.M. López10, I. Agudo11, T. Dauser1, J. Garcia9, A. Kreikenbohm1,2, M. Kadler2, J. Wilms1
1. Dr. Remeis-Sternwarte & Erlangen Centre for Astroparticle Physics, Universität Erlangen-Nürnberg, Sternwartstrasse 7, 96049 Bamberg, Germany
2. Lehrstuhl für Astronomie, Universität Würzburg, Emil-Fischer-Strasse 31, 97074, Würzburg, Germany
3. Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0424, USA
4. Alexander von Humboldt Fellow
5. Centro de Astrobiología (CSIC-INTA), Dep. de Astrofísica, European Space Astronomy Centre, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain
6. Instituto de Astronomía, Universidad Nacional Autónoma de México (UNAM), 04510 Ciudad de México, D.F. México
7. European Space Agency, European Space Astronomy Centre, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain
8. Physics and Astronomy Department, UCLA, Los Angeles, CA 90095-1562, USA
9. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
10. Instituto de Astronomía, Universidad Nacional Autónoma de México, Km 103, Carret, Tijuana-Ensenada, Ensenada 22860, BC, México (P.O. Box 439027, San Ysidro, CA, 92143, USA)
11. Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada, Spain
The morphology of the circumnuclear gas accreting onto supermassive black holes in Seyfert galaxies remains a topic of much debate. As the innermost regions of Active Galactic Nuclei (AGN) are spatially unresolved, X-ray spectroscopy, and in particular line-of-sight absorption variability, is a key diagnostic to map out the distribution of gas. Observations of variable X-ray absorption in multiple Seyferts and over a wide range of timescales indicate the presence of clumps/clouds of gas within the circumnuclear material. Eclipse events by clumps transiting the line of sight allow us to explore the properties of the clumps over a wide range of radial distances from the optical/UV Broad Line Region (BLR) to beyond the dust sublimation radius. Time-resolved absorption events have been extremely rare so far, but suggest a range of density profiles across Seyferts. We resolve a weeks-long absorption event in the Seyfert NGC 3227. We examine six Suzaku and twelve Swift observations from a 2008 campaign spanning 5 weeks. We use a model accounting for the complex spectral interplay of three differently-ionized absorbers. We perform time-resolved spectroscopy to discern the absorption variability behavior. We also examine the IR-to-X-ray spectral energy distribution (SED) to test for reddening by dust. The 2008 absorption event is due to moderately-ionized (log ξ ∼ 1.2-1.4) gas covering 90% of the line of sight. We resolve the density profile to be highly irregular, in contrast to a previous symmetric and centrally-peaked event mapped with RXTE in the same object. The UV data do not show significant reddening, suggesting that the cloud is dust-free. The 2008 campaign has revealed a transit by a filamentary, moderately-ionized cloud of variable density that is likely located in the BLR, and possibly part of a disk wind.
Accepted by A&A
E-mail contact: email@example.com
Preprint available at http://adsabs.harvard.edu/abs/2015arXiv150804565B
AGN Evolution from a Galaxy Evolution Viewpoint
Neven Caplar1, Simon J. Lilly1 and Benny Trakhtenbrot1
1. Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
We explore the connections between the evolving galaxy and AGN populations. We present a simple phenomenological model that links the evolving galaxy mass function and the evolving quasar luminosity function, which makes specific and testable predictions for the distribution of host galaxy masses for AGN of different luminosities. We show that the φ* normalisations of the galaxy mass function and of the AGN luminosity function closely track each other over a wide range of redshifts, implying a constant "duty cycle" of AGN activity. The strong redshift evolution in the AGN L* can be produced by either an evolution in the distribution of Eddington ratios, or in the mbh/m* mass ratio, or both. To try to break this degeneracy we look at the distribution of AGN in the SDSS (mbh, L) plane, showing that an evolving ratio mbh/m* ∝ (1+z)2 reproduces the observed data and also reproduces the local relations which connect the black hole population with the host galaxies for both quenched and star-forming populations. We stress that observational studies that compare the masses of black holes in active galaxies at high redshift with those in quiescent galaxies locally will always see much weaker evolution. Evolution of this form would produce, or could be produced by, a redshift-independent mbh - σ relation and could explain why the local mbh - σ relation is tighter than mbh - m* even if σ is not directly linked to black hole growth. Irrespective of the evolution of mbh/m*, the model reproduces both the appearance of 'downsizing' and the so-called 'sub-Eddington boundary' without any mass-dependence in the evolution of black hole growth rates.
Accepted by ApJ.
E-mail contact: firstname.lastname@example.org
Preprint available at http://arxiv.org/abs/1411.3719
The Fizeau exchange visitors program in optical interferometry funds (travel and accommodation) visits of researchers to an institute of his/her choice (within the European Community) to perform collaborative work and training on one of the active topics of the European Interferometry Initiative. The visits will typically last for one month, and strengthen the network of astronomers engaged in technical, scientific and training work on optical/infrared interferometry. The program is open for all levels of astronomers (Ph.D. students to tenured staff). Non-EU based missions will only be funded if considered essential by the Fizeau Committee. Applicants are strongly encouraged to seek also partial support from their home or host institutions.
The deadline for applications is September 15. Fellowships can be awarded for missions starting in November.
Further informations and application forms can be found at http://www.european-interferometry.eu/
The program is funded by OPTICON/FP7.
Please distribute this message also to potentially interested colleagues outside of your community!
Looking forward to your applications,
Josef Hron & Laszlo Mosoni
(for the European Interferometry Initiative)
E-mail contact: email@example.com