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Sample records for agn sample lbas

  1. CHARACTERIZATION OF A SAMPLE OF INTERMEDIATE-TYPE AGNs. I. SPECTROSCOPIC PROPERTIES AND SERENDIPITOUS DISCOVERY OF NEW DUAL AGNs

    SciTech Connect

    Benitez, Erika; Cruz-Gonzalez, Irene; Martinez, Benoni; Jimenez-Bailon, Elena; Mendez-Abreu, Jairo; Lopez-Martin, Luis; Fuentes-Carrera, Isaura; Leon-Tavares, Jonathan; Chavushyan, Vahram H.

    2013-01-20

    A sample of 10 nearby intermediate-type active galactic nuclei (AGNs) drawn from the Sloan Digital Sky Survey is presented. The aim of this work is to provide estimations of the black hole (BH) mass for the sample galaxies from the dynamics of the broad-line region. For this purpose, a detailed spectroscopic analysis of the objects was done. Using Baldwin-Phillips-Terlevich diagnostic diagrams, we have carefully classified the objects as true intermediate-type AGNs and found that 80%{sup +7.2%} {sub -17.3%} are composite AGNs. The BH mass estimated for the sample is within 6.54 {+-} 0.16 < log M {sub BH} < 7.81 {+-} 0.14. Profile analysis shows that five objects (J120655.63+501737.1, J121607.08+504930.0, J141238.14+391836.5, J143031.18+524225.8, and J162952.88+242638.3) have narrow double-peaked emission lines in both the red (H{alpha}, [N II] {lambda}{lambda}6548,6583 and [S II] {lambda}{lambda}6716, 6731) and the blue (H{beta} and [O III] {lambda}{lambda}4959, 5007) regions of the spectra, with velocity differences ({Delta}V) between the double peaks within 114 km s{sup -1} < {Delta}V < 256 km s{sup -1}. Two of them, J121607.08+504930.0 and J141238.14+391836.5, are candidates for dual AGNs since their double-peaked emission lines are dominated by AGN activity. In searches of dual AGNs, type 1, type II, and intermediate-type AGNs should be carefully separated, due to the high serendipitous number of narrow double-peaked sources (50% {+-} 14.4%) found in our sample.

  2. A complete hard X-ray selected sample of local, luminous AGNs

    NASA Astrophysics Data System (ADS)

    Burtscher, Leonard; Davies, Ric; Lin, Ming-yi; Orban de Xivry, Gilles; Rosario, David

    2016-08-01

    Choosing a very well defined sample is essential for studying the AGN phenomenon. Only the most luminous AGNs can be expected to require a coherent feeding mechanism to sustain their activity and since host galaxy properties and AGN activity are essentially uncorrelated, nuclear scales must be resolved in order to shed light on the feeding mechanisms of AGNs. For these reasons we are compiling a sample of the most powerful, local AGNs. In this talk we present our on-going programme to observe a complete volume limited sample of nearby active galaxies selected by their 14-195 keV luminosity, and outline its rationale for studying the mechanisms regulating gas inflow and outflow.

  3. Testing different AGN tracers on a local sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Pozzi, F.

    2016-08-01

    I will present our new study on a local sample of Seyfert galaxies selected at 12 micron. This sample, given its plenty of information, both photometric and spectroscopic, is a perfect sample to compare, from a statistical point of view, different AGN selection criteria, and AGN derived intrinsic properties. In detail, I will compare AGN activity derived from SED-fitting technique, X-ray luminosity and AGN activity traced by high excitation IR lines, like [NeV] and [OIV]. Moreover, for one particular obscured X-ray Compton-thick source, thanks also to the availability of ALMA data, I will derive a self-consistent overview of the physics behind the emission in different bands,by taking advantage of the photoionization code CLOUDY.

  4. Exploring the Variability Characteristics of the Fermi AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.; Macomb, Daryl J.

    2015-01-01

    The Fermi Gamma-Ray Space Telescope (Fermi) has cataloged nearly 2000 gamma-ray (>100 MeV) point sources of which more than 1100 are likely AGN (these numbers will likely increase by ~50% in the near future with the forthcoming 3FGL catalog). The AGN are predominantly representative of the radio-loud 'blazar' subclass. The emission from these objects is known to be dominated by relativistic beaming and is almost always variable, often exhibiting high-amplitude flaring. To date there have been numerous studies of individual objects including multi-wavelength campaigns with some including parsec-scale radio jet morphological studies. Collectively, these studies have led to new insight in to our understanding of the blazar phenomena and jet propagation. However, there remains a dearth of statistical information on the variability characteristics of the population in aggregate. What, for example, are the distributions of flare amplitudes, durations, temporal profiles and recurrence histories among the gamma-ray blazar subclasses? In two related contributions we present present some results of our study of a large (~103) set of gamma-ray light curves. In this presentation we consider the brightest subset of our identified AGN flares, comprising initially a few tens of events, and then explore in greater detail their properties such as morphologies and their rise and decay timescales. We include where plausible the associated energy dependencies of these rise and decay profiles. We discuss our results in terms and the possible implications on the scale and location of jet structures associated with the emission sites and the cooling timescales of the electron population producing the gamma rays.

  5. Large homogeneous sample of X-ray selected AGN and its study

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.; Paronyan, Gurgen M.; Abrahamyan, Hayk V.

    2015-08-01

    The combined catalogue of AGN (ROSAT BSC/FSC AGN) selected from optical identifications of X-ray sources based on Hamburg--ROSAT Catalogue (HRC) and Byurakan--Hamburg--ROSAT Catalogue (BHRC) is a homogeneous sample for statistical studies. Optically identified X-ray sources from ROSAT Bright Source Catalogue (BSC) and Faint Source Catalogue (FSC) are included, 4253 X-ray selected AGN in total. All these sources are confirmed or candidate AGN based on Hamburg Quasar Survey (HQS) low-dispersion spectra. 3352 of them are listed in the Catalogue of QSOs and Active Galaxies (Véron-Cetty & Véron (2010; 13th version) and 387 are in the Multifrequency Catalogue of Blazars (Roma--BZCAT) by Massaro et al. (2012). We carried out classification for 210 of these candidate sources based on available SDSS spectra and enlarged the sample of confirmed AGN to 3650. A special emphasis is made on narrow-line Sy1.0-Sy1.5 galaxies and QSOs, as many of them have soft X-ray, strong FeII lines, and relatively narrow lines coming from BLR (“narrow broad lines”) we have classified 45 new AGN as such objects. We carried out statistical investigations of the sample, including study of luminosity function, flux-ratios for different ranges, luminosity evolution, etc. Multiwavelength SEDs have also been constructed to follow their behavior for different kinds of AGN and link these SEDs to classifications. The sample is a relevant sources for identification of new blazars.

  6. The X-ray nuclei of radio-loud AGN from the 2Jy sample

    NASA Astrophysics Data System (ADS)

    Hardcastle, Martin

    2009-10-01

    X-ray observations of AGN samples provide crucial information about both the AGN themselves and the material that obscures them. Understanding the properties of the active nuclei of radio-loud AGN is particularly vital given that these objects seem likely to have a key role in models of galaxy formation and evolution. The 2Jy sample of radio galaxies and quasars has uniquely good multiwavelength data, but until recently has been poorly studied in the X-ray. We have recently been awarded time to observe all the low-z 2Jy steep-spectrum sample with Chandra, and here propose short observations of the high-z half of the sample with XMM which will give us a complete picture of the nuclear activity in these objects, and allow a wide range of projects to be carried out.

  7. The X-ray nuclei of radio-loud AGN from the 2Jy sample

    NASA Astrophysics Data System (ADS)

    Hardcastle, Martin

    2010-10-01

    X-ray observations of AGN samples provide crucial information about both the AGN themselves and the material that obscures them. Understanding the properties of the active nuclei of radio-loud AGN is particularly vital given that these objects seem likely to have a key role in models of galaxy formation and evolution. The 2Jy sample of radio galaxies and quasars has uniquely good multiwavelength data, but until recently has been poorly studied in the X-ray. We have recently been awarded time to observe all the low-z 2Jy steep-spectrum sample with Chandra, and here propose short observations of the high-z half of the sample with XMM which will give us a complete picture of the nuclear activity in these objects, and allow a wide range of projects to be carried out.

  8. Exploring the Variability Characteristics of the Fermi AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2016-04-01

    The Fermi Gamma-Ray Space Telescope (Fermi) has cataloged over 3000 gamma-ray (>100 MeV) point sources of which ~70% are likely AGN. The AGN are predominantly representative of the radio-loud “blazar” subclass. The emission from these objects is known to be dominated by relativistic beaming and is almost always variable, often exhibiting high-amplitude flaring. To date there have been numerous studies of individual objects including multi-wavelength campaigns with some including parsec-scale radio jet morphological studies. These studies have led to new insight in to our understanding of the blazar phenomena and jet propagation. However, there remains a dearth of statistical information on the variability characteristics of the population in aggregate. What, for example, are the distributions of flare amplitudes, durations, temporal profiles and recurrence histories among the gamma-ray blazar subclasses? We present some results of our study of a large ( ~103) set of gamma-ray light curves. For the brightest subset we explore in greater detail their properties such as morphologies and their rise and decay timescales. We include where plausible the associated energy dependencies of these rise and decay profiles. We discuss our results in terms of the possible implications on the scale and location of jet structures associated with the emission sites and the cooling timescales of the electron population producing the gamma rays.

  9. The Star-Forming Properties of an Ultra-Hard X-ray Selected Sample of AGN

    NASA Astrophysics Data System (ADS)

    Shimizu, Thomas Taro; Mushotzky, Richard; Melendez, Marcio; Koss, Michael

    2015-08-01

    We present results from our Herschel follow-up survey of the Swift/BAT AGN 58 month catalog. Using the PACS and SPIRE instruments, 313 AGN were imaged at 5 far-infrared (FIR) wavelengths (70, 160, 250, 350, and 500 μm) producing the largest and most complete FIR catalog of local AGN. We combine our FIR photometry with archival mid-infrared photometry to form broadband spectral energy distributions (SEDs) that for the first time reach into the sub-millimeter regime. We fit these SEDs with several models to determine the star-forming properties of the host galaxies such as star-formation rate (SFR), IR luminosity, dust temperature, and dust mass and measure their relationship with various AGN properties such as X-ray luminosity, Eddington ratio, black hole mass, and column density. We find a weak dependence of the global SFR on the AGN strength indicating either the AGN has little influence on star formation over the entire galaxy or that the variability of the AGN on short timescales washes away any correlation between star formation and the AGN. Comparing the BAT AGN to a sample of normal star-forming galaxies on the “main sequence”, we find the BAT AGN systematically have decreased levels of specific SFR (sSFR = SFR/stellar mass). This is possibly indirect evidence that the AGN has suppressed star-formation in its host galaxy. Analysis of the FIR images themselves reveals that many of the BAT AGN are compact which leads to increased levels of SFR surface density, high enough for starburst driven winds. Finally, we show the 70 μm luminosity can be heavily contaminated by AGN emission and should not be used as a SFR indicator for AGN host galaxies.

  10. An infrared and optical analysis of a sample of XBONGs and optically elusive AGNs

    SciTech Connect

    Smith, K. L.; Mushotzky, R. F.; Koss, M. E-mail: richard@astro.umd.edu

    2014-10-20

    We present near-infrared (NIR) spectra of four optically elusive active galactic nuclei (AGNs) and four X-ray bright, optically normal galaxies (XBONGs) from the Swift-BAT survey. With archival observations from the Sloan Digital Sky Survey, the Two Micron All Sky Survey, Spitzer, and the Wide-field Infrared Survey Explorer (WISE), we test a number of AGN indicators in the NIR and mid-infrared; namely, NIR emission line diagnostic ratios, the presence of coronal high-ionization lines, and infrared photometry. Of our eight hard X-ray selected AGNs, we find that optical normalcy has a variety of causes from object to object, and no one explanation applies. Our objects have normal Eddington ratios and so are unlikely to host radiatively inefficient accretion flows. It is unlikely that star formation in the host or starlight dilution is contributing to their failure of optical diagnostics, except perhaps in two cases. The NIR continua are well fit by two blackbodies: one at the stellar temperature, and a hot dust component near the dust sublimation temperature. The XBONGs are more likely to have significant hot dust components, while these components are small relative to starlight in the optically elusive AGN. Some of our sample have NIR line ratios typical of AGNs, but NIR diagnostics are unsuccessful in distinguishing H II regions from AGNs in general. In one object, we discover a hidden broad-line region in the NIR. These results have strong relevance to the origin of optically normal AGNs in deep X-ray surveys.

  11. Line Shape Variability in a Sample of AGN with Broad Lines

    NASA Astrophysics Data System (ADS)

    Ilić, D.; Popović, L. Č.; Shapovalova, A. I.; Burenkov, A. N.; Chavushyan, V. H.; Kovačević, A.

    2015-12-01

    The spectral variability of active galactic nuclei (AGN) is one of the key features that enables us to study in more detail, the structure of AGN emitting regions. Especially, the broad line profiles that vary both in flux and shape, give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. We give here a comparative review of the line shape variability in a sample of five type 1 AGNs, those with broad emission lines in their spectra, of the data obtained from the international long-term optical monitoring campaign coordinated by the Special Astrophysical Observatory of the Russian Academy of Science. The main aim of this campaign is to study the physics and kinematics of the BLR on a uniform data set, focusing on the problems of the photoionization heating of the BLR and its geometry, where, in this paper, we give for a first time, a comparative analysis of the variabilty of five type 1 AGNs, discussing their complex BLR physics and geometry in the framework of the estimates of the supermassive black hole mass in AGN.

  12. Statistics of broad relativistic lines in AGN: a counts- and flux-limited sampl

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2006-10-01

    We propose to observe 10 X-ray unabsorbed Active Galactic Nuclei (AGN) extracted from the RXTE Slew Survey (XSS). We aim at completing the XMM-Newton coverage of a flux-limited [2-10 keV flux > 1 mCrab] sub-sample of the XSS with enough statistical quality to unambiguously establish the presence of a relativistically broadened K-alpha iron line in the spectrum of each individual object. Measuring the fraction of local universe AGN where effects due to a relativistic accretion disk are detected, along with the accurate determination of the accretion flow physical properties, will allow us to tell if and how the standard paradigm needs to be modified to explain the origin of the energy output in AGN. The total requested time is 975 ks

  13. A New Sample of Low-Mass AGNs Selected by X-ray Variability

    NASA Astrophysics Data System (ADS)

    Terashima, Yuichi

    2012-09-01

    We present results from our attempts to search for AGN containing relatively low-mass black holes (BHs) using X-ray variability. Variability time scales inversely correlate with black hole mass and can be used to select low-mass objects. We utilize the second XMM-Newton serendipitous source catalogue, which contains 262902 unique sources, to select highly variable objects. Black hole masses are derived by using the correlation between BH mass and normalized excess variance, where the effect of break in power spectra is properly taken into account. We present the sample selection and results of analysis including discovery of candidate low-mass AGNs with mass lower than 2e6 Msolar. We also present results on a peculiar AGN candidate showing soft thermal emission only found in our survey.

  14. Circumnuclear Star Formation in the BAT AGN Sample: High Resolution Radio Morphologies and SFRs

    NASA Astrophysics Data System (ADS)

    Smith, Krista Lynne; Mushotzky, Richard; Vogel, Stuart N.; Miller, Neal A.

    2016-04-01

    It has long been an assumption that active galaxies would obey the same far-infrared (FIR) - radio correlation established for star-forming normal galaxies. This assumption has been used by numerous high-z studies, but has recently come into doubt for two main reasons: the revelation that the AGN itself may contribute non-negligibly to the FIR emission, and different radio emission physics in the vicinity of the active nucleus than in isolated HII regions. Studies have attempted to decompose the FIR spectral energy distributions to remove the AGN contribution and then calculate the star formation rate (SFR). It would then be ideal to compare this to another, independent measure of SFR. We have conducted a high-resolution (0.3-1'') JVLA survey of an unbiased sample of nearby, hard X-ray selected AGN in order to spatially decompose the extended star formation emission from the central compact source. We present these maps of the nuclear regions of 41 AGN from the Swift-BAT sample. The objects exhibit a wide range of circumnuclear radio morphologies, including mini-jets and star-forming rings. When the central compact source is removed, the extended emission does indeed conform to the FIR-radio correlation. A subset of the objects also remain compact in our 1'' and 0.3'' observations, implying very high star formation surface densities which may be capable of driving significant winds.

  15. Obscured AGN

    NASA Astrophysics Data System (ADS)

    Barger, Amy

    2014-07-01

    Obscured AGN may correspond to a substantial fraction of the supermassive black hole growth rate. I will present new surveys with the SCUBA-2 instrument on the James Clerk Maxwell Telescope of the Chandra Deep Fields and discuss whether we can distinguish obscured AGN in hard X-ray and radio selected samples using submillimeter observations.

  16. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

    2010-01-01

    \\Ve compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 microns, [Ne II] 12.81 microns, [Ne III] 15.56 microns and [Ne V] 14.32 microns, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGNs are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT luminosities suggests that the emission lines primarily arise in gas ionized by the AGN. We also compared the mid-IR emission-lines in the BAT AGNs with those from published studies of star-forming galaxies and LINERs. We found that the BAT AGN fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. From this we found that sources that have been previously classified in the mid-infrared/optical as AGN have smaller emission line ratios than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGN represents the main contribution to the observed line emission. Overall, we present a different set of emission line diagnostics to distinguish between AGN and star forming galaxies that can be used as a tool to find new AGN.

  17. Stellar population properties for a sample of hard X-ray AGNs

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Calvi, V.; Masetti, N.; Parisi, P.; Landi, R.; Maiorano, E.; Minniti, D.; Galaz, G.

    2013-08-01

    Aims: The aim of this paper is to study the stellar population of galaxies hosting an active galactic nucleus (AGN). We studied a subsample of hard X-ray emitting AGNs from the INTEGRAL and Swift catalogs, which were previously identified and characterized through optical spectroscopy. Our analysis provides complementary information, namely age and metallicity, which is necessary to complete the panoramic view of these interesting objects. Methods: We selected hard X-ray emitting objects, identified as AGNs, by checking their optical spectra in search of absorption lines suitable for the stellar population analysis. We obtained a final sample consisting of 20 objects with a redshift lower than 0.3. We used the full-spectrum fitting method; particularly, we use penalized pixel method and apply the PPXF code. After masking all the regions affected by emission lines, we fitted the spectra with the MILES single stellar population templates, and we derived mass-weighted ages and metallicities. Results: Most of the objects in our sample show an old stellar population; however, three of them are characterized by a bimodal distribution with a non-negligible contribution from young stars. The values of the mass-weighted metallicity span a wide range with most of them slightly above the solar value. No relations between the stellar population properties and the morphological ones have been found. Table 1 and Figs. 3-5 are available in electronic form at http://www.aanda.org

  18. X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN

    NASA Technical Reports Server (NTRS)

    Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

    2007-01-01

    The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) < 3 x 10(exp 25)/sq cm), local (< z >= 0.03), AGN sample. We find 9/22 low absorption (n(sub H) < 10(exp 23)/sq cm), simple power law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds (1997) and George et al. (1998), who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. Additionally, the remaining sources (13122) have more complex spectra, well-fit by an absorbed power law at E > 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

  19. The dependence of the soft X ray spectral slope with radio property, luminosity, and redshift, for a large sample of AGN from the Einstein IPC data base

    NASA Technical Reports Server (NTRS)

    Brunner, H.; Worrall, D. M.; Wilkes, Belinda J.; Elvis, Martin

    1989-01-01

    The dependence of the soft X-ray spectral slope on radio, optical and X-ray properties, and on redshift are reported for a large sample of Active Galactic Nuclei (AGN). The sample includes 317 optically and radio-selected AGN from a preliminary version of the Einstein Imaging Proportional Counter (IPC) quasar and AGN data base. The main results are: the difference in X-ray slope between radio-loud and radio-quiet AGN were confirmed for an independent and much larger sample of sources; a difference in X-ray slope between flat and steep radio spectrum AGN is observed only in high luminosity sub-sample; in flat radio spectrum AGNs there is an indication for a dependence of the X-ray spectral index on X-ray luminosity redshift and alpha sub 0x.

  20. BATSE Observations of the Piccinotti Sample of AGN II: Variability and Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2001-01-01

    The Piccinotti sample is the hard x-ray-selected sample of active galactic nuclei (AGNs) best studied at energies below approximately 10 keV. It represents the only unbiased and complete high-energy survey of the sky down to a limiting flux of 3.1 x 10(exp -11) per square erg per second. As such, it has been used to study AGN properties such as X-ray spectral characteristics, log N-log S relation, and luminosity function. The BATSE data provide, for the first time, a systematic coverage of the whole sample at high energies. BATSE data from nearly four years of observations (1993 November - 1997 September) were analyzed using standard BATSE occultation analysis software to extract a signal from sources in the Piccinotti sample. Although the BATSE sensitivity for individual source measurements is relatively poor on short time scales, the near all-sky coverage and long CGRO lifetime allows us to improve our sensitivity considerably by sumrrng data over many years. This significantly reduces our statistical errors at the expense of loss of temporal information. However, the systematic errors associated with the summation of data over such a long period are not negligible, and the study of systematic effects was a major part of our effort. We evaluated two types of systematic error: those affecting the overall normalization (which are important for comparison with other instruments) and those affecting the size of the fluctuations (which are relevant for estimating the confidence level of a detection). The former was studied by comparison of BATSE data with other instruments, primarily CGRO/OSSE. The results indicate that our absolute flux values maybe overestimated by as much as 35% for some sources. However, since this does not affect our estimation of the detection confidence, we made no corrections to our flux estimates.

  1. VizieR Online Data Catalog: X-ray properties of AGN from the CJF sample (Britzen+, 2007)

    NASA Astrophysics Data System (ADS)

    Britzen, S.; Brinkmann, W.; Campbell, R. M.; Gliozzi, M.; Readhead, A. C. S.; Browne, I. W. A.; Wilkinson, P.

    2008-01-01

    We present the soft X-ray properties obtained in the ROSAT All-Sky survey and from pointed PSPC observations for the AGN in the complete flux-density limited Caltech-Jodrell Bank flat spectrum sample (hereafter CJF). CJF is a VLBI survey (VLBA observations at 5GHz) of 293 AGN with detailed information on jet component motion. We investigate and discuss the soft X-ray properties of this AGN sample and examine the correlations between X-ray and VLBI properties, test beaming scenarios, and search for the discriminating properties between the sub-samples detected and not detected by ROSAT. Comparing the observed and the predicted X-ray fluxes by assuming an Inverse Compton (IC) origin for the observed X-rays, we compute the beaming or Doppler factor, {delta}IC, for the CJF sources and compare it with the equipartition Doppler factor, {delta}EQ. We further contrast the Doppler factors with other beaming indicators derived from the VLBI observations, such as the value of the expansion velocity, and the observed and intrinsic brightness temperature. We calculate two different core dominance parameters (R): the ratio of total VLBI flux to single-dish flux, RV, and the ratio of the VLBI core-component flux to single-dish flux, RC. In addition, we investigate the large-scale radio structure of the AGN and the difference between the pc- and kpc-scale structure (misalignment) with regard to the X-ray observations. (6 data files).

  2. The MIXR sample: AGN activity versus star formation across the cross-correlation of WISE, 3XMM, and FIRST/NVSS

    NASA Astrophysics Data System (ADS)

    Mingo, B.; Watson, M. G.; Rosen, S. R.; Hardcastle, M. J.; Ruiz, A.; Blain, A.; Carrera, F. J.; Mateos, S.; Pineau, F.-X.; Stewart, G. C.

    2016-11-01

    We cross-correlate the largest available mid-infrared (Wide-field Infrared Survey Explorer - WISE), X-ray (3XMM) and radio (Faint Images of the Radio Sky at Twenty centimetres+NRAO VLA Sky Survey) catalogues to define the MIXR sample of AGN and star-forming galaxies. We pre-classify the sources based on their positions on the WISE colour/colour plot, showing that the MIXR triple selection is extremely effective to diagnose the star formation and AGN activity of individual populations, even on a flux/magnitude basis, extending the diagnostics to objects with luminosities and redshifts from SDSS DR12. We recover the radio/mid-IR star formation correlation with great accuracy, and use it to classify our sources, based on their activity, as radio-loud and radio-quiet active galactic nuclei (AGN), low excitation radio galaxies/low ionization nuclear emission line regions, and non-AGN galaxies. These diagnostics can prove extremely useful for large AGN and galaxy samples, and help develop ways to efficiently triage sources when data from the next generation of instruments becomes available. We study bias in detail, and show that while the widely used WISE colour selections for AGN are very successful at cleanly selecting samples of luminous AGN, they miss or misclassify a substantial fraction of AGN at lower luminosities and/or higher redshifts. MIXR also allows us to test the relation between radiative and kinetic (jet) power in radio-loud AGN, for which a tight correlation is expected due to a mutual dependence on accretion. Our results highlight that long-term AGN variability, jet regulation, and other factors affecting the Q/Lbol relation, are introducing a vast amount of scatter in this relation, with dramatic potential consequences on our current understanding of AGN feedback and its effect on star formation.

  3. Long-term X-ray spectral variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Skipper, C. J.; Emmanoulopoulos, D.

    2016-07-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In nine of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For six objects, with a low accretion rate as a fraction of the Eddington rate (dot{m}_{Edd}), Γ is anticorrelated with dot{m}_{Edd}, i.e. `harder-when-brighter' behaviour is observed. The three higher dot{m}_{Edd}-rate objects show a positive correlation between Γ and dot{m}_{Edd}. This transition from harder-when-brighter at low dot{m}_{Edd}to softer-when-brighter at high dot{m}_{Edd} can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonizing corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that low-ionization nuclear emission-line regions are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion rate end of the hard state or in the hard-intermediate state.

  4. Mid- and Near-infrared spectral properties of a sample of Swift-BAT X-ray selected AGNs

    NASA Astrophysics Data System (ADS)

    Castro, Angel; Miyaji, Takamitsu; Malkan, Matthew A.; Ichikawa, Kohei; Ueda, Yoshihiro; Shirahata, M.; Nakagawa, Takao; Imanishi, Masatoshi; Oyabu, Shinki

    2015-08-01

    We present a comparative study of the mid- (MIR) to near-infrared (NIR) properties of a sample of X-ray selected AGNs from the Swift/Burst Alert Telescope (BAT) 70-month all-sky hard X-ray (14-195 keV) survey. For a sample of 78 AGNs, including both Seyfert 1 and Seyfert 2 sources with black hole masses derived from 2MASS K-band magnitudes and literature, we obtain spectroscopic data from the IRC (2.5 - 5 μm) and IRS (in the 5-14 μm band) instruments onboard the Akari and Spitzer satellites, respectively. We test possible correlations between the 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 μm polycyclic aromatic hydrocarbon (PAH) emission features, the continuum slope and CO optical depth, as well as CO2, H2O, and amorphous silicates. Using the 3.3, 6.2 and 11.3 μm PAH emission features as a proxy for the star-formation rate (SFR) we report the AGN type and Eddington-ratio dependences of circum-nuclear star formation.

  5. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, D.; Zakamska, N.

    2016-06-01

    Feedback from active galactic nuclei (AGN) is widely considered to be the main driver in regulating the growth of massive galaxies. It operates by either heating or driving the gas that would otherwise be available for star formation out of the galaxy, preventing further increase in stellar mass. Observational proof for this scenario has, however, been hard to come by. We have assembled a large sample of 133 radio-quiet type-2 and red AGN at 0.1sample, we measure the gas kinematics of the AGN-ionized gas, the stellar masses of the host galaxies and their star formation rates. We then investigate the relationships between AGN luminosities, specific star formation rates (sSFR) and outflow strengths W_{90} - the 90% velocity width of the [OIII]λ5007Å line power and a proxy for the AGN-driven outflow speed. Outflow strength W_{90} is independent of sSFR for AGN selected based on their mid-IR luminosity. This is in agreement with previous work that demonstrates that star formation is not sufficient to produce the observed ionized gas outflows which have to be powered by AGN activity. More importantly, we find a negative correlation between W_{90} and sSFR in the AGN hosts with the highest star formation rates, i.e., with the highest gas content. This relationship implies that AGN with strong outflow signatures are hosted in galaxies that are more `quenched' considering their stellar mass than galaxies with weaker outflow signatures. This correlation is only seen in AGN host galaxies with SFR >100 M_{⊙} yr^{-1} where presumably the coupling of the AGN-driven wind to the gas is strongest. This observation is consistent with the AGN having a net suppression, or `negative' impact, through feedback on the galaxies' star formation history.

  6. Constraints on Black Hole Spin in a Sample of Broad Iron Line AGN

    NASA Technical Reports Server (NTRS)

    Brenneman, Laura W.; Reynolds, Christopher S.

    2008-01-01

    We present a uniform X-ray spectral analysis of nine type-1 active galactic nuclei (AGN) that have been previously found to harbor relativistically broadened iron emission lines. We show that the need for relativistic effects in the spectrum is robust even when one includes continuum "reflection" from the accretion disk. We then proceed to model these relativistic effects in order to constrain the spin of the supermassive black holes in these AGN. Our principal assumption, supported by recent simulations of geometrically-thin accretion disks, is that no iron line emission (or any associated Xray reflection features) can originate from the disk within the innermost stable circular orbit. Under this assumption, which tends to lead to constraints in the form of lower limits on the spin parameter, we obtain non-trivial spin constraints on five AGN. The spin parameters of these sources range from moderate (a approximates 0.6) to high (a > 0.96). Our results allow, for the first time, an observational constraint on the spin distribution function of local supermassive black holes. Parameterizing this as a power-law in dimensionless spin parameter (f(a) varies as absolute value of (a) exp zeta), we present the probability distribution for zeta implied by our results. Our results suggest 90% and 95% confidence limits of zeta > -0.09 and zeta > -0.3 respectively.

  7. Determination of free Zn2+ concentration in synthetic and natural samples with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique).

    PubMed

    Chito, Diana; Weng, Liping; Galceran, Josep; Companys, Encarnació; Puy, Jaume; van Riemsdijk, Willem H; van Leeuwen, Herman P

    2012-04-01

    The determination of free Zn(2+) ion concentration is a key in the study of environmental systems like river water and soils, due to its impact on bioavailability and toxicity. AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique) are emerging techniques suited for the determination of free heavy metal concentrations, especially in the case of Zn(2+), given that there is no commercial Ion Selective Electrode. In this work, both techniques have been applied to synthetic samples (containing Zn and NTA) and natural samples (Rhine river water and soils), showing good agreement. pH fluctuations in DMT and N(2)/CO(2) purging system used in AGNES did not affect considerably the measurements done in Rhine river water and soil samples. Results of DMT in situ of Rhine river water are comparable to those of AGNES in the lab. The comparison of this work provides a cross-validation for both techniques.

  8. Obscured AGN

    NASA Technical Reports Server (NTRS)

    Ptak, Andrew

    2011-01-01

    Many obscured AGN show evidence of significant starburst emission dominating below 2 keV. Therefore wide-field X-ray surveys sensitive enough to luminosities below approximately 10^42 ergs per second will result in detections of galaxies with contributions of both obscured AGN and starburst emission. We will discuss Bayesian approaches to assessing the relative contribution of each component, minimizing survey biases and using the resultant posterior probabilities for the AGN and starburst components to determine their evolution.

  9. Usefulness of Chromogenic CromoCen® AGN agar medium for the identification of the genus Aeromonas: Assessment of faecal samples.

    PubMed

    Aguilera-Arreola, M G; Portillo-Muñoz, M I; Rodríguez-Martínez, C; Castro-Escarpulli, G

    2012-08-01

    Selective screening media for the detection and identification of Aeromonas strains are needed to guide primary isolation procedures in the clinical laboratory. This study compared the selective CromoCen® AGN chromogenic agar medium for the detection and identification of Aeromonas strains that were isolated from various samples against the conventional selective agar media that are commonly used for the isolation of this organism in food, environmental and clinical samples. The Miles and Misra and ecometric methods were used to evaluate the microbiological performance of CromoCen® AGN chromogenic agar medium, which was shown to be satisfactory. A total of 14 reference Aeromonas strains, 44 wild strains and 106 clinical stool specimens were examined using both non-chromogenic selective agars that are commonly used for Aeromonas isolation and CromoCen® AGN agar. The latter exhibited 94.73% sensitivity and 100% specificity for the various samples. On CromoCen® AGN agar medium, Aeromonas formed colonies with light green, greenish and salmon pigments with or without a surrounding wide transparent zone (halo) of 2-3mm in diameter around the entire border. This medium is recommended for the isolation and potential identification of the Aeromonas genus.

  10. Correlations of the IR Luminosity and Eddington Ratio with a Hard X-ray Selected Sample of AGN

    NASA Technical Reports Server (NTRS)

    Mushotzy, Richard F.; Winter, Lisa M.; McIntosh, Daniel H.; Tueller, Jack

    2008-01-01

    We use the SWIFT Burst Alert Telescope (BAT) sample of hard x-ray selected active galactic nuclei (AGN) with a median redshift of 0.03 and the 2MASS J and K band photometry to examine the correlation of hard x-ray emission to Eddington ratio as well as the relationship of the J and K band nuclear luminosity to the hard x-ray luminosity. The BAT sample is almost unbiased by the effects of obscuration and thus offers the first large unbiased sample for the examination of correlations between different wavelength bands. We find that the near-IR nuclear J and K band luminosity is related to the BAT (14 - 195 keV) luminosity over a factor of 10(exp 3) in luminosity (L(sub IR) approx.equals L(sub BAT)(sup 1.25) and thus is unlikely to be due to dust. We also find that the Eddington ratio is proportional to the x-ray luminosity. This new result should be a strong constraint on models of the formation of the broad band continuum.

  11. Starburst or AGN dominance in submm-luminous candidate AGN

    NASA Astrophysics Data System (ADS)

    Coppin, Kristen; Alexander, Dave; Aretxaga, Itziar; Blain, Andrew; Chapman, Scott; Clements, Dave; Dunlop, James; Dunne, Loretta; Dye, Simon; Farrah, Duncan; Hughes, David; Ivison, Rob; Kim, Sungeun; Menendez-Delmestre, Karin; Oliver, Sebastian; Page, Mat; Pope, Alexandra; Rowan-Robinson, Michael; Scott, Douglas; Smail, Ian; Swinbank, Mark; Vaccari, Mattia; van Kampen, Eelco

    2008-03-01

    It is widely believed that starbursts/ULIRGs and AGN activity are triggered by galaxy interactions and merging; and sub-mm selected galaxies (SMGs) seem to be simply high redshift ULIRGs, observed near the peak of activity. In this evolutionary picture every SMG would host an AGN, which would eventually grow a black hole strong enough to blow off all of the gas and dust leaving an optically luminous QSO. In order to probe this evolutionary sequence, a crucial sub-sample to focus on would be the 'missing link' sources, which demonstrate both strong starburst and AGN signatures and to determine if the starburst is the main power source even in SMGs when we have evidence that an AGN is present. The best way to determine if a dominant AGN is present is to look in the mid-IR for their signatures, since often even deep X-ray observations miss identifying the presence of AGN in heavily dust-obscured SMGs. We have selected a sample of SMGs which are good candidates for harboring powerful AGN on the basis of their IRAC colours (S8um/S4.5um>2). Once we confirm these SMGs are AGN-dominated, we can then perform an audit of the energy balance between star-formation and AGN within this special sub-population of SMGs where the BH has grown appreciably to begin heating the dust emission. The proposed observations with IRS will probe the physics of how SMGs evolve from a cold-dust starburst-dominated ULIRG to an AGN/QSO by measuring the level of the mid-IR continuum, PAH luminosity, and Si absorption in these intermediate `transitory' AGN/SMGs.

  12. AGN torus emission for a homogeneous sample of bright flat-spectrum radio quasars

    NASA Astrophysics Data System (ADS)

    Castignani, G.; De Zotti, G.

    2015-01-01

    We have selected a complete sample of 80 flat-spectrum radio quasars (FSRQs) from the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year catalog within the Sloan Digital Sky Survey (SDSS) area, all with measured redshift, and have inspected their spectral energy distributions (SEDs) looking for evidence of an active galactic nucleus torus emission. A SED fitting algorithm has found such evidence for seven objects and an uncertain indication for one more. A further analysis has picked out four additional FSRQs whose observed SEDs may be consistent with the presence of a torus. All 12 of these FSRQs belong to the subsample of 55 sources showing the optical-ultraviolet bump interpreted as thermal emission from a standard accretion disk. Torus luminosities have been estimated for the eight objects whose torus was identified by the fitting algorithm. For the other 47 FSRQs in the subsample, including the 4 with indications of torus emission not spotted by the algorithm, we have derived upper limits to the torus luminosity. Our analysis shows that the torus can show up clearly only under quite special conditions: low luminosity and preferentially low peak frequency of the beamed synchrotron emission from the jet; high torus luminosity, close to that of the accretion disk. This implies that the inferred ratios of torus to disk luminosity are biased high. The median value, considering upper limits as detections (survival analysis techniques are found to be inapplicable because of the excessive fraction of upper limits), is Ltorus/Ldisk ~ 1 while studies of radio quiet quasars yield average ratios ⟨ Ltorus/Ldisk ⟩ ≃ 1 / 3-1 / 2. On the other hand, although our poor statistics does not allow us to draw firm conclusions, our results are compatible with the FSRQ tori having the same properties as those of radio quiet quasars. At variance with another investigation of optically selected BL Lacs, we find that the Wide-field Infrared Survey Explorer (WISE) infrared

  13. The Close AGN Reference Survey (CARS)

    NASA Astrophysics Data System (ADS)

    Rothberg, Barry; Husemann, Bernd; Busch, Gerold; Dierkes, Jens; Eckart, Andreas; Krajnovic, Davor; Scharwaechter, Julia; Tremblay, Grant R.; Urrutia, Tanya

    2015-08-01

    We present the first science results from the Close AGN Reference Survey (CARS). This program is a snapshot survey of 39 local type 1 AGN (0.01 < z <0.06) designed to address the issue of AGN-driven star formation quenching by characterizing the condition for star formation in AGN host galaxies. The primary sample was observed with Multi Unit Spectrscopic Explorer (MUSE), an optical wavelength integral field unit (IFU) with a 1'x1' field of view on the VLT. The optical 3D spectroscopy complements existing sub-mm CO(1-0) data and near-IR imaging to establish a unique dataset combining molecular and stellar masses with star formation rates, gas, stellar kinematics and AGN properties. The primary goals of CARS are to:1) investigate if the star formation efficiency and gas depletion time scales are suppressed as a consequence of AGN feedback; 2) identify AGN-driven outflows and their relation to the molecular gas reservoir of the host galaxy; 3) investigate the the balance of AGN feeding and feedback through the ratio of the gas reservoir to the AGN luminosity; and 4) provide the community with a reference survey of local AGN with a high legacy value. Future work will incorporate near-infrared IFU observations to present a complete spatially resolved picture of the interplay among AGN, star-formation, stellar populations, and the ISM.

  14. Statistical Analysis of the Long Baseline Variability Properties of a Large Gamma-Ray Selected Blazar AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2013-06-01

    The Fermi Gamma-Ray Space Telescope has cataloged over 1800 gamma-ray (>100 MeV) point sources of which more than 1100 are identified with AGN. These AGN, and a large number of unidentified high-latitude objects of which a large fraction are also likely AGN, are predominantly representative of the radio-loud “blazar” subclass. The emission from these objects is well known to be beaming dominated and is almost always variable, often exhibiting high-amplitude flaring. To date there have been numerous studies of individual objects including multi-wavelength campaigns in some cases including parsec-scale radio jet morphological study. Collectively, this has led to new insight in to our understanding of the blazar phenomena and jet propagation in general. However, there remains a dearth of information on the collective variability characteristics of the population as a statistical ensemble. What, for example, are the distributions of flare amplitudes, durations, temporal profiles and recurrence histories among the gamma-ray blazar subclasses? Given the unprecedented sky coverage of Fermi - the full sky is observed approximately every two orbits leading to an approximate one part in 6 monitoring duty cycle for any point on the sky - we have begun to explore this issue. A light curve database compiled and maintained (weekly) by the Fermi Science Support Center contains flux histories for every source in the Fermi 2FGL catalog. In this contribution, we present our analysis of the statistical properties of the high-latitude component of this light curve database.

  15. AGN from HeII: AGN host galaxy properties & demographics

    NASA Astrophysics Data System (ADS)

    Baer, Rudolf E.; Schawinski, Kevin; Weigel, Anna

    2016-01-01

    We present an analysis of HeII emitting objects classified as AGN. In a sample of 81'192 galaxies taken from the seventh data release (DR7) of the Sloan Digital Sky Survey in the redshift interval 0.02 < z < 0.05 and with r < 17 AB mag, the Baldwin, Philips & Terlevitsch 1981 method (BPT) identifies 1029 objects as active galactic nuclei. By applying an analysis using HeII λ 4686 emission lines, based on Shirazi & Binchmann 2012, we have identified an additional 283 active galactic nuclei, which were missed by the BPT method. This represents an increase of over 25 %. The characteristics of the HeII selected AGN are different from the AGN found through the PBT; the colour - mass diagram and the colour histogram both show that HeII selected AGN are bluer. This new selection technique can help inform galaxy black hole coevolution scenarios.

  16. Accretion Timescales from Kepler AGN

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.

    2015-01-01

    We constrain AGN accretion disk variability mechanisms using the optical light curves of AGN observed by Kepler. AGN optical fluxes are known to exhibit stochastic variations on timescales of hours, days, months and years. The excellent sampling properties of the original Kepler mission - high S/N ratio (105), short sampling interval (30 minutes), and long sampling duration (~ 3.5 years) - allow for a detailed examination of the differences between the variability processes present in various sub-types of AGN such as Type I and II Seyferts, QSOs, and Blazars. We model the flux data using the Auto-Regressive Moving Average (ARMA) representation from the field of time series analysis. We use the Kalman filter to determine optimal mode parameters and use the Akaike Information Criteria (AIC) to select the optimal model. We find that optical light curves from Kepler AGN cannot be fit by low order statistical models such as the popular AR(1) process or damped random walk. Kepler light curves exhibit complicated power spectra and are better modeled by higher order ARMA processes. We find that Kepler AGN typically exhibit power spectra that change from a bending power law (PSD ~ 1/fa) to a flat power spectrum on timescales in the range of ~ 5 - 100 days consistent with the orbital and thermal timescales of a typical 107 solar mass black hole.

  17. Probing AGN Accretion Physics through AGN Variability: Insights from Kepler

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal Pramod

    Active Galactic Nuclei (AGN) exhibit large luminosity variations over the entire electromagnetic spectrum on timescales ranging from hours to years. The variations in luminosity are devoid of any periodic character and appear stochastic. While complex correlations exist between the variability observed in different parts of the electromagnetic spectrum, no frequency band appears to be completely dominant, suggesting that the physical processes producing the variability are exceedingly rich and complex. In the absence of a clear theoretical explanation of the variability, phenomenological models are used to study AGN variability. The stochastic behavior of AGN variability makes formulating such models difficult and connecting them to the underlying physics exceedingly hard. We study AGN light curves serendipitously observed by the NASA Kepler planet-finding mission. Compared to previous ground-based observations, Kepler offers higher precision and a smaller sampling interval resulting in potentially higher quality light curves. Using structure functions, we demonstrate that (1) the simplest statistical model of AGN variability, the damped random walk (DRW), is insufficient to characterize the observed behavior of AGN light curves; and (2) variability begins to occur in AGN on time-scales as short as hours. Of the 20 light curves studied by us, only 3-8 may be consistent with the DRW. The structure functions of the AGN in our sample exhibit complex behavior with pronounced dips on time-scales of 10-100 d suggesting that AGN variability can be very complex and merits further analysis. We examine the accuracy of the Kepler pipeline-generated light curves and find that the publicly available light curves may require re-processing to reduce contamination from field sources. We show that while the re-processing changes the exact PSD power law slopes inferred by us, it is unlikely to change the conclusion of our structure function study-Kepler AGN light curves indicate

  18. The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

    SciTech Connect

    Ajello, M.; Alexander, D.M.; Greiner, J.; Madejski, G.M.; Gehrels, N.; Burlon, D.; /Garching, Max Planck Inst., MPE

    2012-04-02

    Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of {approx}2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a {approx}5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN-LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN-LogS of AGN selected above 10 keV is now established to a {approx}10% precision. We derive the luminosity function of Compton-thick AGN and measure a space density of 7.9{sub -2.9}{sup +4.1} x 10{sup -5} Mpc{sup -3} for objects with a de-absorbed luminosity larger than 2 x 10{sup 42} erg s{sup -1}. As the BAT AGN are all mostly local, they allow us to investigate the spatial distribution of AGN in the nearby Universe regardless of absorption. We find concentrations of AGN that coincide spatially with the largest congregations of matter in the local ({le} 85 Mpc) Universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

  19. Radio Loud AGNs are Mergers

    NASA Astrophysics Data System (ADS)

    Chiaberge, Marco; Gilli, Roberto; Lotz, Jennifer M.; Norman, Colin

    2015-06-01

    We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei (AGNs) at z\\gt 1 using new samples. The objects have Hubble Space Telescope (HST) images taken with Wide Field Camera 3 (WFC3) in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z\\gt 1 and to a sample of non-active galaxies. We also consider lower redshift radio galaxies with HST observations and previous generation instruments (NICMOS and WFPC2). The full sample spans an unprecedented range in both redshift and AGN luminosity. We perform statistical tests to determine whether the different samples are differently associated with mergers. We find that all (92%-14%+8%) radio-loud galaxies at z\\gt 1 are associated with recent or ongoing merger events. Among the radio-loud population there is no evidence for any dependence of the merger fraction on either redshift or AGN power. For the matched radio-quiet samples, only 38%-15+16 are merging systems. The merger fraction for the sample of non-active galaxies at z\\gt 1 is indistinguishable from radio-quiet objects. This is strong evidence that mergers are the triggering mechanism for the radio-loud AGN phenomenon and the launching of relativistic jets from supermassive black holes (SMBHs). We speculate that major black hole (BH)-BH mergers play a major role in spinning up the central SMBHs in these objects.

  20. The dust covering factor in AGN

    NASA Astrophysics Data System (ADS)

    Stalevski, Marko

    2016-08-01

    We undertook a critical investigation of a common estimator of the dust covering factor in active galactic nuclei (AGN). The infrared radiation emitted by the obscuring dusty structure ("the dusty torus") is nothing but a reprocessed fraction of the accretion disk emission, so the ratio of their luminosities (L_torus /L_AGN) should correspond to the fraction of the AGN sky obscured by dust. Using state-of-the-art Monte Carlo radiative transfer code, we calculated a grid of spectral energy distributions (SEDs) emitted by the clumpy two-phase dusty structure. Using this grid of SEDs, we studied the relation between L_torus /L_AGN and the dust covering factor for different parameters of the torus. We found that in case of type 1 AGNs, due to the torus anisotropy, L_torus/L AGN underestimate low covering factors and overestimate high covering factors. In type 2 AGNs covering factors are always underestimated. Our results provide a novel easy-to-use method to account for anisotropy and obtain correct covering factors. Using two samples from the literature, we demonstrated the importance of these effects for inferring the obscured AGN fraction. We found that after the anisotropy is properly accounted for, the dust covering factors show very weak dependence on L_AGN, with values in the range of approx. 0.6 ‑ 0.7. Our results suggest a higher fraction of obscured AGNs at high luminosities than those found by X-ray surveys. We discuss the possible causes of this discrepancy and demonstrate that it is partially due to the presence of a Compton-thick AGN population, which is missed by X-ray surveys, but not by infrared.

  1. Multi-faceted AGN

    NASA Astrophysics Data System (ADS)

    Farrar, Glennys R.; Chen, Yanping; Dai, Yuxiao; Zaw, Ingyin

    2016-08-01

    An interesting question is how frequently an object is an AGN by multiple different criteria — e.g., is simultaneously a narrow-line optical AGN and an X-ray or radio AGN, possibly as a function of luminosities in the various wavebands and perhaps host galaxy type. Answering such questions quantitatively has been difficult up to now because of the lack of a complete, uniformly selected optical AGN catalog. Here we report first results of such an analysis, using the new, all-sky catalog of uniformly selected optical AGNs from Zaw, Chen and Farrar (2016), the Swift-BAT 70-month catalog of X-ray AGN (Baumgartner et al., 2013), and the van Velzen et al. (2012) catalog of radio AGN.

  2. Decreased specific star formation rates in AGN host galaxies

    NASA Astrophysics Data System (ADS)

    Shimizu, T. Taro; Mushotzky, Richard F.; Meléndez, Marcio; Koss, Michael; Rosario, David J.

    2015-09-01

    We investigate the location of an ultra-hard X-ray selected sample of active galactic nuclei (AGN) from the Swift Burst Alert Telescope (BAT) catalogue with respect to the main sequence (MS) of star-forming galaxies using Herschel-based measurements of the star formation rate (SFR) and M*'s from Sloan Digital Sky Survey photometry where the AGN contribution has been carefully removed. We construct the MS with galaxies from the Herschel Reference Survey and Herschel Stripe 82 Survey using the exact same methods to measure the SFR and M* as the Swift/BAT AGN. We find that a large fraction of the Swift/BAT AGN lie below the MS indicating decreased specific SFR (sSFR) compared to non-AGN galaxies. The Swift/BAT AGN are then compared to a high-mass galaxy sample (CO Legacy Database for GALEX Arecibo SDSS Survey, COLD GASS), where we find a similarity between the AGN in COLD GASS and the Swift/BAT AGN. Both samples of AGN lie firmly between star-forming galaxies on the MS and quiescent galaxies far below the MS. However, we find no relationship between the X-ray luminosity and distance from the MS. While the morphological distribution of the BAT AGN is more similar to star-forming galaxies, the sSFR of each morphology is more similar to the COLD GASS AGN. The merger fraction in the BAT AGN is much higher than the COLD GASS AGN and star-forming galaxies and is related to distance from the MS. These results support a model in which bright AGN tend to be in high-mass star-forming galaxies in the process of quenching which eventually starves the supermassive black hole itself.

  3. VizieR Online Data Catalog: WISE data for radio-loud AGN complete samples (Gurkan+, 2014)

    NASA Astrophysics Data System (ADS)

    Gurkan, G.; Hardcastle, M. J.; Jarvis, M. J.

    2014-11-01

    The 3CRR, 2Jy, 6CE and 7CE samples were chosen for our analysis. We used the revised subsample of the 3CR catalogue of radio sources (Bennett, 1962MNRAS.125...75B), which have flux densities greater than 10.9Jy at 178MHz (Laing, Riley & Longair, 1983MNRAS.204..151L, Cat. J/MNRAS.204.151). There are 172 sources with 0.0029sample chosen for our analysis is a subsample of the 2Jy objects, which has homogeneous spectroscopic observations (Wall & Peacock, 1985MNRAS.216..173W, Cat. J/MNRAS/216/173; Tadhunter et al. 1993MNRAS.263..999T). The complete sample was generated selecting radio objects with flux densities above 2Jy at 2.7GHz. Our subsample consists of 48 steep-spectrum sources (objects dominated by emission from the beamed relativistic jet and core components are excluded so that we minimize the contamination from non-thermal emission) with 0.05sample has 10 LERGs, 20 NLRGs, 13 BLRGs and 5 quasars. The 6CE subsample is drawn from the 6C survey (Baldwin et al., 1985MNRAS.217..717B, Cat. VIII/18) and was designed to select objects fainter than 3C objects, in order to investigate the cosmic evolution of radio galaxies (Eales 1985MNRAS.217..149E; Eales et al. 1997MNRAS.291..593E). The flux density limit for the sample is 2<=S_151+<=3.93Jy. It has virtually complete spectroscopic redshift measurements as well as IR imaging . The 6CE sample has 58 sources including 19 LERGs, 28 HERGs and 9 quasars, whose redshift ranges between 0.105 and 3.395. The 7CE sample, drawn from the 7C survey (Visser et al., 1995A&AS..110..419V, Cat. J/A+AS/110/419), is a complete sample having flux densities greater than 0.5Jy at 151MHz (Willott et al., 1998MNRAS.300..625W, 2002MNRAS.335

  4. Radio Loud AGNs are Mergers

    NASA Astrophysics Data System (ADS)

    Chiaberge, Marco; Gilli, Roberto; Lotz, Jennifer M.; Norman, Colin

    2015-06-01

    We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei (AGNs) at z\\gt 1 using new samples. The objects have Hubble Space Telescope (HST) images taken with Wide Field Camera 3 (WFC3) in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z\\gt 1 and to a sample of non-active galaxies. We also consider lower redshift radio galaxies with HST observations and previous generation instruments (NICMOS and WFPC2). The full sample spans an unprecedented range in both redshift and AGN luminosity. We perform statistical tests to determine whether the different samples are differently associated with mergers. We find that all (92%-14%+8%) radio-loud galaxies at z\\gt 1 are associated with recent or ongoing merger events. Among the radio-loud population there is no evidence for any dependence of the merger fraction on either redshift or AGN power. For the matched radio-quiet samples, only 38%-15+16 are merging systems. The merger fraction for the sample of non-active galaxies at z\\gt 1 is indistinguishable from radio-quiet objects. This is strong evidence that mergers are the triggering mechanism for the radio-loud AGN phenomenon and the launching of relativistic jets from supermassive black holes (SMBHs). We speculate that major black hole (BH)–BH mergers play a major role in spinning up the central SMBHs in these objects.

  5. AGN Identification and Host Galaxy Properties in the MOSDEF Survey

    NASA Astrophysics Data System (ADS)

    Coil, Alison

    2016-08-01

    I will present new results on the identification and host galaxy properties of X-ray, IR, and optically-selected AGN at 1.4 < z < 3.8, using spectroscopic data from the on-going MOSDEF survey. MOSDEF is obtaining rest-frame optical spectra of ~1300 galaxies and AGN using the newly commissioned MOSFIRE instrument on Keck. We find clear selection biases when identifying AGN at different wavelengths, in that AGN at any wavelength are typically found in more massive galaxies, while optically-selected AGN are also more likely to be found in galaxies with low SFR, while IR AGN are typically found in galaxies with higher SFR. We also find that optical and X-ray AGN selection identifies AGN with a wider range of accretion rates than IR AGN selection. By combining AGN samples selected at different wavelengths, we find that AGN host galaxies have similar stellar age and dust content as inactive galaxies of the same stellar mass.

  6. THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI: THE EFFECT OF HOST-GALAXY STARLIGHT ON LUMINOSITY MEASUREMENTS. II. THE FULL SAMPLE OF REVERBERATION-MAPPED AGNs

    SciTech Connect

    Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.; Netzer, Hagai; Vestergaard, Marianne E-mail: peterson@astronomy.ohio-state.edu E-mail: netzer@wise.tau.ac.il

    2009-05-20

    We present high-resolution Hubble Space Telescope images of all 35 active galactic nuclei (AGNs) with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to ground-based spectroscopic luminosity measurements at 5100 A. After correcting the luminosities of the AGNs for the contribution from starlight, we re-examine the H{beta} R {sub BLR}-L relationship. Our best fit for the relationship gives a power-law slope of 0.52 with a range of 0.45-0.59 allowed by the uncertainties. This is consistent with our previous findings, and thus still consistent with the naive assumption that all AGNs are simply luminosity-scaled versions of each other. We discuss various consistency checks relating to the galaxy modeling and starlight contributions, as well as possible systematic errors in the current set of reverberation measurements from which we determine the form of the R {sub BLR}-L relationship.

  7. Low luminosity AGNs in the local universe

    NASA Astrophysics Data System (ADS)

    Ikiz, Tuba; Peletier, Reynier F.; Yesilyaprak, Cahit

    2016-04-01

    Galaxies are known to contain black holes (e.g. Ferrarese & Merritt 2000), whose mass correlates with the mass of their bulge. A fraction of them also has an Active Galactic Nucleus (AGN), showing excess emission thought to be due to accretion of mass by the supermassive black hole at the center of the galaxy. It is thought that AGNs play a very important role during the formation of galaxies by creating large outflows that stop star formation in the galaxy (see e.g. Kormendy & Ho 2013). The aim is to detect the fraction of Low Luminosity Active Galactic Nucleus (LLAGN) in the nearby Universe. At present, they are typically found using optical spectroscopy (e.g. Kauffmann, Heckman et al. 2003), who discuss the influence of the AGN on the host galaxy and vice versa. However, optical spectra are seriously affected by extinction in these generally very dusty objects, and therefore can only give us partial information about the AGN. I used a newly-found method, and apply it to the S4G sample, a large, complete, sample of nearby galaxies, which I am studying in detail with a large collaboration, to detect the fraction of low luminosity AGNs, and to better understand the relation between AGNs and their host galaxy which is thought to be crucial for their formation.

  8. Steps Toward Unveiling the True Population of AGN: Photometric Selection of Broad-Line AGN

    NASA Astrophysics Data System (ADS)

    Schneider, Evan; Impey, C.

    2012-01-01

    We present an AGN selection technique that enables identification of broad-line AGN using only photometric data. An extension of infrared selection techniques, our method involves fitting a given spectral energy distribution with a model consisting of three physically motivated components: infrared power law emission, optical accretion disk emission, and host galaxy emission. Each component can be varied in intensity, and a reduced chi-square minimization routine is used to determine the optimum parameters for each object. Using this model, both broad- and narrow-line AGN are seen to fall within discrete ranges of parameter space that have plausible bounds, allowing physical trends with luminosity and redshift to be determined. Based on a fiducial sample of AGN from the catalog of Trump et al. (2009), we find the region occupied by broad-line AGN to be distinct from that of quiescent or star-bursting galaxies. Because this technique relies only on photometry, it will allow us to find AGN at fainter magnitudes than are accessible in spectroscopic surveys, and thus probe a population of less luminous and/or higher redshift objects. With the vast availability of photometric data in large surveys, this technique should have broad applicability and result in large samples that will complement X-ray AGN catalogs.

  9. Properties and evolution of radio-AGN hosts since z~4

    NASA Astrophysics Data System (ADS)

    Delvecchio, Ivan

    2016-08-01

    We analyse the multi-wavelength properties of about 6200 radio (3-GHz) selected sources in the COSMOS field to investigate the impact of AGN activity on the integrated properties of their hosts. Two main classes of AGN are identified: radiatively-efficient AGN, by combining X-ray, mid-IR diagnostics and SED decomposition, and radiatively-inefficient AGN, that show up only in radio. Interestingly, we find significantly distinct galaxy properties for the two AGN classes, as a function of redshift. At z<2, radiatively-inefficient AGN are typically found in more massive and less star-forming galaxies than radiatively-efficient AGN, while at higher redshift we observe a possible reversal of their stellar mass distributions. We interpret these trends in the context of the anti-hierarchical growth of AGN host galaxies, with a particular focus on the role of AGN feedback over cosmic time in radio-selected samples.

  10. Multi-Wavelength AGN from Ground and Space, from Far-IR to High-Energy

    NASA Astrophysics Data System (ADS)

    Stern, Daniel

    2014-07-01

    I will discuss multi-wavelength AGN studies, with a focus on mid-IR and radio selected obscured AGN. Obscured AGN, which are robustly identified across the full sky by WISE, are the dominant AGN population. I will discuss several aspects of the mid-IR obscured AGN population, ranging from detailed studies of extreme sources, the so-called WISE ultraluminous `hot dust-obscured galaxy' or `hot DOG' sample, as well as more general studies comparing obscured and unobscured AGN identified in wide-area surveys.

  11. The Evolution of Obscuration in AGN

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, M.; Virani, S.

    2006-09-01

    One fundamental ingredient in our understanding of the AGN population is the ratio of obscured to unobscured AGN and whether this ratio depends on other parameters like intrinsic luminosity or redshift. Observationally, deep X-ray surveys found that the obscured AGN fraction depends on luminosity. However, the dependence on redshift is less clear. In this work, we constructed the largest sample to date of AGN selected in hard X-rays, containing a total of 1229 sources, 631 of them obscured, with a high spectroscopic completeness in order to study the possible dependence of the fraction of obscured sources with redshift and/or luminosity. We confirm that this fraction decreases with increasing luminosity as previously reported and found that at the same time it increases with increasing redshift. This is the first time that this evolution is significantly detected using only optical spectroscopy to separate obscured and unobscured AGN. Additionally, we use the spectral shape and intensity of the X-ray background as a separate constraint on the evolution of the obscured AGN fraction finding consistent results. This result can be interpreted as an evolution in the location of the obscuration, from the central parsec-scale region (the torus) at low redshift to kiloparsec scales (the host galaxy) at high redshift, as it is known that most galaxies contained more dust in the past. Using these results, we calculate the integrated bolometric AGN emission finding it to be at most 5% of the total extragalactic light. Hence, while AGN contribute most of the light at X-ray wavelengths, they constitute only a small fraction of the integrated extragalactic light. We thank the support of the Centro de Astrof\\'{\\i}sica FONDAP and from NASA/{\\it INTEGRAL} grant NNG05GM79G.

  12. Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

    SciTech Connect

    Pace, Cameron; Salim, Samir E-mail: salims@indiana.edu

    2014-04-10

    We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

  13. Neutrinos from AGN

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes; White, Nicholas E. (Technical Monitor)

    2000-01-01

    The great penetrating power of neutrinos makes them ideal probe of astrophysical sites and conditions inaccessible to other forms of radiation. These are the centers of stars (collapsing or not) and the centers of Active Galactic Nuclei (AGN). It has been suggested that AGN presented a very promising source of high energy neutrinos, possibly detectable by underwater neutrino detectors. This paper reviews the evolution of ideas concerning the emission of neutrinos from AGN in view of the more recent developments in gamma-ray astronomy and their implications for the neutrino emission from these class of objects.

  14. The merger fraction of radio-loud and radio quiet AGN: clues on the AGN triggering mechanism

    NASA Astrophysics Data System (ADS)

    Chiaberge, Marco

    2016-08-01

    Radio-loud AGNs are important objects. They are associated with the most massive black holes and thus with the most massive galaxies, and they are often located in clusters of galaxies. Studying radio galaxies at z>1 not only allows us to get insights on the mechanisms responsible for launching their powerful relativistic jets, but also to better understand important aspects of the formation and evolution of massive galaxies and clusters. I will focus on results obtained from our successful HST snapshot survey of 3CR radio-loud AGN at z>1. Statistical analysis of different samples of carefully selected radio-quiet AGN, radio-loud AGN and non-active galaxies shows strong evidence that galaxy mergers (and possibly black hole mergers) are intimately tied to the triggering mechanism for radio-loud AGN activity. The same may not hold for the radio-quiet AGN class.

  15. Search for the Multiwavelength AGN Properties in Dependence on Environment

    NASA Astrophysics Data System (ADS)

    Vavilova, Iryna; Chesnok, Nadya; Melnyk, Olga

    We present new results on the research of isolated AGNs and quasars which are located in regions with the low density environment. Our sample of AGNs was compiled at the basis of the 2MIG Catalog (2MASS Isolated Galaxies, Karachentseva et al., Bull. SAO RAS, 2010) and Catalog of AGNs by Veron+ 2006. The 2MIG Catalog' galaxies (N=3227) were chosen by Karachentseva's isolation criterion, stellar magnitude Ks= 4,0 -12,0 and angle diameters a¿ 30', effective catalog depth -6000 km/s. Our sample of isolated AGNs contains 48 objects as well as the sample of galaxies by Mrk type (N=40) from 2MIG catalog was compiled separately. We analyze the main physical properties of AGNs from these samples in comparison with environment using the isolation parameter as the distance to neighbors (Vavilova et al., Astron. Nachr., 2009). Additionally, for isolated galaxies of Mrk type we calculated their masses by Eddington limit formula (Chesnok et al., AIP, 2009) as well as we considered the spectral properties of isolated AGNs chosen from SDSS catalogue. Altogether our sample of isolated AGNs is presented by the objects having different manifestory properties in IR, visual, UV, X-ray and radio ranges of the electromagnetic waves that allows us to consider it as the unique laboratory for the AGNs study n dependence on the environment.

  16. Optically-selected AGN

    NASA Astrophysics Data System (ADS)

    Richard, Gordon

    2016-08-01

    will discuss the selection and properties of optically-selected AGN as contrasted with other multi-wavelength investigations. While optical surveys are able to identify *more* AGNs than other wavelengths, this size comes with a bias towards brighter, unobscured sources. Although optical surveys are not ideal for probing obscured AGNs, I will discuss how they can guide our search for them. The bias towards unobscured sources in the optical is partially mitigated, however, by an increase in information content for the sources that *are* identified---in the form of physics probed by the combination of optical continuum, absorption, and emission. An example is the ability to estimate the mass of AGNs based on the optical/UV emission lines. I will discuss the range of mass (and accretion rate) probed by the optical in addition to serious biases in the black hole mass scaling relations that corrupt these estimates at high redshift.

  17. PRIMUS: The Relationship between Star Formation and AGN Accretion

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Aird, James; Coil, Alison L.; Moustakas, John; Mendez, Alexander J.; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun

    2015-06-01

    We study the evidence for a connection between active galactic nuclei (AGNs) fueling and star formation by investigating the relationship between the X-ray luminosities of AGNs and the star formation rates (SFRs) of their host galaxies. We identify a sample of 309 AGNs with {10}41\\lt {L}X\\lt {10}44 erg s-1 at 0.2\\lt z\\lt 1.2 in the PRIMUS redshift survey. We find AGNs in galaxies with a wide range of SFR at a given LX. We do not find a significant correlation between SFR and the observed instantaneous LX for star-forming AGN host galaxies. However, there is a weak but significant correlation between the mean LX and SFR of detected AGNs in star-forming galaxies, which likely reflects that LX varies on shorter timescales than SFR. We find no correlation between stellar mass and LX within the AGN population. Within both populations of star-forming and quiescent galaxies, we find a similar power-law distribution in the probability of hosting an AGN as a function of specific accretion rate. Furthermore, at a given stellar mass, we find a star-forming galaxy ˜2-3 more likely than a quiescent galaxy to host an AGN of a given specific accretion rate. The probability of a galaxy hosting an AGN is constant across the main sequence of star formation. These results indicate that there is an underlying connection between star formation and the presence of AGNs, but AGNs are often hosted by quiescent galaxies.

  18. Clues to the Structure of AGN Through Massive Variability Surveys

    NASA Astrophysics Data System (ADS)

    Lawrence, A.

    2016-06-01

    Variability studies hold information on otherwise unresolvable regions in Active Galactic Nuclei (AGN). Population studies of large samples likewise have been very productive for our understanding of AGN. These two themes are coming together in the idea of systematic variability studies of large samples - with SDSS, PanSTARRS, and soon, LSST. I summarise what we have learned about the optical and UV variability of AGN, and what it tells us about accretion discs and the BLR. The most exciting recent results have focused on rare large-scale outbursts and collapses - Tidal Disruption Events, changing-look AGN, and large amplitude microlensing. All of these promise to give us new insight into AGN physics.

  19. Propiedades de los AGNs oscurecidos y no oscurecidos

    NASA Astrophysics Data System (ADS)

    Taormina, M.; Bornancini, C.

    In this work we analyze the properties of obscured and unobscured AGNs selected from the "Multiwavelength Survey by Yale-Chile" (MUSYC). The sample of AGNs was selected base on their mid-infrared colors ([3.6], [4.5], [5.8] y [8.0] μm), from images obtained with the Spitzer Space Telescope. We select obscured and unobscured AGN samples using a simple criterion based on the observed optical to mid-IR color with limits R - [4.5] = 3.04 (AB system) and with redshifts in the range 1 < z < 3. Obscured AGNs are intrinsically optically faint in the R band, suggesting that luminous IR- selected AGNs have significant dust extinction. FULL TEXT IN SPANISH

  20. Observational evidence for thin AGN disks

    NASA Technical Reports Server (NTRS)

    Netzer, Hagai

    1992-01-01

    AGN spectrum and spectral features, polarization, inclination, and X-ray line and continuum reflection features are discussed in a critical way in order to determine the ones that are the least model-dependent. The sign and strength of absorption and emission edges are found to be model-dependent, and relativistic broadening and shifting makes them hard to detect. The presence or absence of the predicted Lyman edge polarization feature may be used as a decisive test for thin, bare AGN disks. Other good model-independent tests are several inclination-related line and continuum correlations in big AGN samples. It is shown that electron temperature near the surface of the disk can greatly exceed the disk equilibrium temperature, which causes deviations from LTE. This effect must be incorporated into realistic disk models.

  1. Host Galaxy Properties of the Swift BAT Ultra Hard X-Ray Selected AGN

    NASA Technical Reports Server (NTRS)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

    2011-01-01

    We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift Burst Alert Telescope (BAT) sample. The BAT AGN host galaxies have intermediate optical colors (u -- r and g -- r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log Stellar Mass >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] Lambda 5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

  2. AGN content of X-ray, IR and radio sources

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.; Paronyan, G. M.; Abrahamyan, H. V.; Gyulzadyan, M. V.; Mikayelyan, G. A.

    2016-09-01

    We have carried out a number of surveys and identification works related to X-ray, IR and radio sources and searched for extragalactic ones. Among them, most interesting are Active Galactic Nuclei (AGN) and Starburst (SB) Galaxies. Some 4500 AGN have been revealed from ROSAT BSC and FSC sources, and many more are hidden ones; those showing evidence of activity but with no emission lines in optical wavelengths. We estimated AGN content of X-ray sources as 52.9%. IR sources contain thousands of SBs, and most important are those having signs of interaction and/or merging. We have carried out optical identifications of IRAS point sources, and 1278 IR galaxies have been revealed, including LIRGs and ULIRGs. We have also combined IRAS PSC and FSC catalogs and compiled its extragalactic sample, which allowed to estimate AGN content among IR sources as 23.7%. Extragalactic radio sources contain bright galaxies, AGN and SBs. We have studied the border between AGN and normal galaxies by radio/optical flux ratios to establish which objects may be attributed to AGN based on radio properties. Interestingly, absolute majority of objects associated with both X-ray and radio sources are AGN.

  3. The Starburst-AGN Connection under the Multiwavelength Limelight

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2011-11-01

    Since the discovery of a tight relation between supermassive black hole masses, the bulge luminosity, and the stellar velocity dispersion in the local universe galaxies, mounting experimental evidence has been collected pointing to a connection between nuclear activity and star formation over a wide range of redshifts. Although a growing number of galaxies from different samples exhibit simultaneous starburst and AGN phenomenology, it is still a matter of debate whether this is the smoking gun of a causal relation between them, and, if so, with which trend. Basic issues in modern astrophysics, such as the evolution of galaxies and supermassive black holes, AGN feeding and feedback to the interstellar and intergalactic medium, as well as the role played by the environment on the star formation history are related to this "Starburst-AGN Connection". This Workshop aims at gathering observational and theoretical astronomers so as to answer the following questions: * The "Starburst-AGN Connection": A causal relation? * "Starburst-AGN Connection" at low and high redshift: any evidence for evolution? * Is there a connection between AGN obscuration and star formation? * In which way are the star formation and AGN phenomena affected by the environment? * Do stars contribute to AGN fueling? Multiwavelength observations in the last decade have given a paramount contribution to improve our understanding in this field. The Workshop will build on this panoptic view, and aims at contributing to the scientific case of future ground-based and space large observatories.

  4. A UV to mid-IR study of AGN selection

    SciTech Connect

    Chung, Sun Mi; Kochanek, Christopher S.; Assef, Roberto; Brown, Michael J. I.; Stern, Daniel; Jannuzi, Buell T.; Gonzalez, Anthony H.; Hickox, Ryan C.; Moustakas, John

    2014-07-20

    We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 deg{sup 2} Boötes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts for ∼20,000 objects, primarily from the AGN and Galaxy Evolution Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are σ/(1 + z) = 0.040 and σ/(1 + z) = 0.169, respectively, with the worst 5% outliers excluded. On the basis of the χ{sub ν}{sup 2} of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I = 23.5 mag. We compare the SED fits for a galaxy-only model and a galaxy-AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGNs, including spatially resolved AGNs with significant contributions from the host galaxy and objects with the emission line ratios of 'composite' spectra. We also use our results to compare with the X-ray, mid-IR, optical color, and emission line ratio selection techniques. For an F-ratio threshold of F > 10, we find 16,266 AGN candidates brighter than I = 23.5 mag and a surface density of ∼1900 AGN deg{sup –2}.

  5. Multiwavelength Studies of X-ray Selected AGN

    NASA Astrophysics Data System (ADS)

    Paronyan, G. M.; Mickaelian, A. M.; Abrahamyan, H. V.

    2016-06-01

    We present multiwavelength studies of the AGN and galaxy samples of the HRC/BHRC Joint Catalogue, optical identifications of ROSAT BSC and FSC sources. The extragalactic sample contains 4253 candidate AGN and 492 galaxies without a sign of activity. Multiwavelength data were retrieved from γ-ray to radio providing 62 photometric points in the range 100 GeV - 151 MHz. Color-color diagrams were built to investigate the nature of these objects. Activity types were taken from the SDSS DR12 spectroscopic database, as well as NED and HyperLEDA. So far, 451 objects remain as AGN candidates to be confirmed by spectroscopic observations.

  6. SWIFT Observations AGN

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard

    2008-01-01

    I will present results from the x-ray and optical follow-up observations of the Swift Burst Alert Telescope (BAT) Active Galactic Nuclei (AGN) survey. I will discuss the nature of obscuration in these objects, the relationship to optical properties and the change of properties with luminosity and galaxy type.

  7. Mini-Survey on SDSS OIII AGN with Swift

    NASA Technical Reports Server (NTRS)

    Angelini, Lorella

    2008-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. There is a common wisdom that every massive galaxy has a massive black hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low $L_X$ (at all $z$). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of {it optically-selected samples} shows no such break and no differences between narrow and broad-line objects. Assuming both hard X-ray and [O{\\sc iii}] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a min-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([O{\\sc iii}]) to check the relation with the $L_X$ observed with Swift.

  8. Xray cavities in a sample of 83 SPT-selected clusters galaxies. Tracing the evolution of AGN feedback in clusters of galaxies out to z=1.2

    SciTech Connect

    Hlavacek-Larrondo, J.; McDonald, M.; Benson, B. A.; Forman, W. R.; Allen, S. W.; Bleem, L. E.; Ashby, M. L. N.; Bocquet, S.; Brodwin, M.; Dietrich, J. P.; Jones, C.; Liu, J.; Reichardt, C. L.; Saliwanchik, B. R.; Saro, A.; Schrabback, T.; Song, J.; Stalder, B.; Vikhlinin, A.; Zenteno, A.

    2015-05-18

    X-ray cavities are key tracers of mechanical (or radio mode) heating arising from the active galactic nuclei (AGNs) in brightest cluster galaxies (BCGs). We report on a survey for X-ray cavities in 83 massive, high-redshift ($0.4\\lt z\\lt 1.2$) clusters of galaxies selected by their Sunyaev-Zel’dovich signature in the South Pole Telescope data. Based on Chandra X-ray images, we find a total of six clusters having symmetric pairs of surface brightness depressions consistent with the picture of radio jets inflating X-ray cavities in the intracluster medium (ICM). The majority of these detections are of relatively low significance and require deeper follow-up data in order to be confirmed. Further, this search will miss small (<10 kpc) X-ray cavities that are unresolved by Chandra at high ($z\\gtrsim 0.5$) redshift. Despite these limitations, our results suggest that the power generated by AGN feedback in BCGs has remained unchanged for over half of the age of the universe ($\\gt 7$ Gyr at $z\\sim 0.8$). On average, the detected X-ray cavities have powers of $(0.8-5)\\times {{10}^{45}}\\ {\\rm erg}\\ {{{\\rm s}}^{-1}}$, enthalpies of $(3-6)\\times {{10}^{59}}\\ {\\rm erg}$, and radii of ~17 kpc. Integrating over 7 Gyr, we find that the supermassive black holes in BCGs may have accreted 10(8) to several ${{10}^{9}}\\,{{M}_{\\odot }}$ of material to power these outflows. This level of accretion indicates that significant supermassive black hole growth may occur not only at early times, in the quasar era, but at late times as well. We also find that X-ray cavities at high redshift may inject an excess heat of 0.1–1.0 keV per particle into the hot ICM above and beyond the energy needed to offset cooling. Although this result needs to be confirmed, we note that the magnitude of excess heating is similar to the energy needed to preheat clusters, break self-similarity, and explain the excess entropy in hot atmospheres.

  9. Does the obscured AGN fraction really depend on luminosity?

    NASA Astrophysics Data System (ADS)

    Sazonov, S.; Churazov, E.; Krivonos, R.

    2015-12-01

    We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ≲ 1042.5 erg s-1 (17-60 keV), and decreases to ≲60 per cent at L ≳ 1044 erg s-1. In terms of the half-opening angle θ of an obscuring torus, this implies that θ ≲ 30° in lower luminosity AGN, and θ ≳ 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/dΩ ∝ cos α, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle θ ˜ 30°.

  10. The Prevalence of Gas Outflows in Type 2 AGNs

    NASA Astrophysics Data System (ADS)

    Woo, Jong-Hak; Bae, Hyun-Jin; Son, Donghoon; Karouzos, Marios

    2016-02-01

    To constrain the nature and fraction of the ionized gas outflows in active galactic nuclei (AGNs), we perform a detailed analysis on gas kinematics as manifested by the velocity dispersion and shift of the [{{O}}\\{{III}}] λ5007 emission line, using a large sample of ˜39,000 type 2 AGNs at z < 0.3. First, we confirm a broad correlation between [{{O}} {{III}}] and stellar velocity dispersions, indicating that the bulge gravitational potential plays a main role in determining the [{{O}} {{III}}] kinematics. However, [{{O}} {{III}}] velocity dispersion is on average larger than stellar velocity dispersion by a factor of 1.3-1.4 for AGNs with double Gaussian [{{O}} {{III}}], suggesting that the non-gravitational component, i.e., outflows, is almost comparable to the gravitational component. Second, the increase of the [{{O}} {{III}}] velocity dispersion (after normalized by stellar velocity dispersion) with both AGN luminosity and Eddington ratio suggests that non-gravitational kinematics are clearly linked to AGN accretion. The distribution in the [{{O}} {{III}}] velocity-velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the launching velocity of gas outflows increases with AGN luminosity. Third, the majority of luminous AGNs present the non-gravitational kinematics in the [{{O}} {{III}}] profile. These results suggest that ionized gas outflows are prevalent among type 2 AGNs. On the other hand, we find no strong trend of the [{{O}} {{III}}] kinematics with radio luminosity, once we remove the effect of the bulge gravitational potential, indicating that ionized gas outflows are not directly related to radio activity for the majority of type 2 AGNs.

  11. Star Formation Quenching and Identifying AGN in Galaxies

    NASA Astrophysics Data System (ADS)

    Mendez, Alexander; Coil, A. L.; Lotz, J. M.; Aird, J.; Diamond-Stanic, A. M.; Moustakas, J.; Salim, S.; Simard, L.; Blanton, M. R.; Eisenstein, D.; Wong, K. C.; Cool, R. J.; Zhu, G.; PRIMUS; AEGIS

    2014-01-01

    I will discuss two observational projects related to galaxy and active galactic nuclei (AGN) evolution at z < 1. First I will present a statistical study of the morphologies of galaxies in which star formation is being shut down or quenched; this has implications for how red, elliptical galaxies are formed. I will discuss the physical processes behind star formation quenching from the morphological transformations that galaxies undergo during this process. Then I will focus on multi-wavelength AGN selection methods and tie together disparate results in the literature. Several IR-AGN selection methods have been developed using Spitzer/IRAC data in order to supplement traditional X-ray AGN selection; I will characterize the uniqueness and complementarity of these methods as a function of both IR and X-ray depth. I will use data from the PRIsm MUlti-object Survey (PRIMUS) to compare the efficiency of IR and X-ray AGN selection and discuss the properties of the AGN and host galaxy populations of each. Finally, I will briefly mention ongoing work to compare the clustering of observed IR and X-ray AGN samples relative to stellar mass-matched galaxy samples.

  12. PRIMUS: INFRARED AND X-RAY AGN SELECTION TECHNIQUES AT 0.2 < z < 1.2

    SciTech Connect

    Mendez, Alexander J.; Coil, Alison L.; Aird, James; Diamond-Stanic, Aleksandar M.; Moustakas, John; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu Guangtun

    2013-06-10

    We present a study of Spitzer/IRAC and X-ray active galactic nucleus (AGN) selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each. We investigate how the overlap and possible contamination of the samples depend on the depth of both the IR and X-ray data. We use Spitzer/IRAC imaging, Chandra and XMM-Newton X-ray imaging, and spectroscopic redshifts from the PRism MUlti-object Survey to construct galaxy and AGN samples at 0.2 < z < 1.2 over 8 deg{sup 2}. We construct samples over a wide range of IRAC flux limits (SWIRE to GOODS depth) and X-ray flux limits (10 ks to 2 Ms). We compare IR-AGN samples defined using both the IRAC color selection of Stern et al. and Donley et al. with X-ray-detected AGN samples. For roughly similar depth IR and X-ray surveys, we find that {approx}75% of IR-selected AGNs are also identified as X-ray AGNs. This fraction increases to {approx}90% when comparing against the deepest X-ray data, indicating that at most {approx}10% of IR-selected AGNs may be heavily obscured. The IR-AGN selection proposed by Stern et al. suffers from contamination by star-forming galaxies at various redshifts when using deeper IR data, though the selection technique works well for shallow IR data. While similar overall, the IR-AGN samples preferentially contain more luminous AGNs, while the X-ray AGN samples identify a wider range of AGN accretion rates including low specific accretion rate AGNs, where the host galaxy light dominates at IR wavelengths. The host galaxy populations of the IR and X-ray AGN samples have similar rest-frame colors and stellar masses; both selections identify AGNs in blue, star-forming and red, quiescent galaxies.

  13. Absorbing Outflows in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  14. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  15. Spectral decomposition of broad-line agns and host galaxies

    SciTech Connect

    Vanden Berk, Daniel E.; Shen, Jiajian; Yip, Ching-Wa; Schneider, Donald P.; Connolly, Andrew J.; Burton, Ross E.; Jester, Sebastian; Hall, Patrick B.; Szalay, Alex S.; Brinkmann, John; /Apache Point Observ.

    2005-09-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasingly bluer than early-type galaxies with increasing host luminosity. Most of the AGNs with detected hosts are emitting at between 1% and 10% of their estimated Eddington luminosities, but the sensitivity of the technique usually does not extend to the Eddington limit. There are mild correlations among the AGN and host galaxy eigencoefficients, possibly indicating a link between recent star formation and the onset of AGN activity. The catalog of spectral reconstruction parameters is available as an electronic table.

  16. Studying AGN Feedback with Galactic Outflows in Luminous Obscured Quasar

    NASA Astrophysics Data System (ADS)

    Sun, Ai-Lei

    2016-01-01

    Feedback from Active galactic nuclei (AGN) has been proposed as an important quenching mechanism to suppress star formation in massive galaxies. We investigate the most direct form of AGN feedback - galactic outflows - in the most luminous obscured AGN (L>10^45 erg/s) from the SDSS sample in the nearby universe (z<0.2). Using ALMA and Magellan observations to target molecular and ionized outflows, we find that luminous AGN can impact the dynamics and phase of the galactic medium, and confirm the complex multi-phase and multi-scaled nature of the feedback phenomenon. In particular, we found that most of these luminous AGN hosts ionized outflows. The outflow size, velocity, and energetics correlate with the AGN luminosity, and can be very extended (r > 10 kpc) and fast (v > 1000 km/s) for the most luminous ones. I end with presenting a new technique to find extended ionized outflows using broadband imaging surveys, and to characterize their occurrence rate, morphology, size distribution, and their dependence on the AGN luminosity. This technique will open a new window for feedback studies in the era of large-scale optical imaging surveys, e.g., HSC and then LSST.

  17. The Keck OSIRIS Nearby AGN (KONA) Survey: AGN Fueling and Feedback

    NASA Astrophysics Data System (ADS)

    Hicks, Erin K. S.; Müller-Sánchez, Francisco; Malkan, Matthew A.; Yu, Po-Chieh

    In an effort to better constrain the relevant physical processes dictating the co-evolution of supermassive black holes and the galaxies in which they reside we turn to local Seyfert AGN. It is only with these local AGN that we can reach the spatial resolution needed to adequately characterize the inflow and outflow mechanisms thought to be the driving forces in establishing the relationship between black holes and their host galaxies at higher redshift. We present the first results from the KONA (Keck OSIRIS Nearby AGN) survey, which takes advantage of the integral field unit OSIRIS plus laser and natural guide star adaptive optics to probe down to scales of 5-30 parsecs in a sample of 40 local Seyfert galaxies. With these K-band data we measure the two-dimensional distribution and kinematics of the nuclear stars, molecular gas, and ionized gas within the central few hundred parsecs.

  18. The VIMOS VLT Deep Survey final data release: a spectroscopic sample of 35 016 galaxies and AGN out to z ~ 6.7 selected with 17.5 ≤ iAB ≤ 24.75

    NASA Astrophysics Data System (ADS)

    Le Fèvre, O.; Cassata, P.; Cucciati, O.; Garilli, B.; Ilbert, O.; Le Brun, V.; Maccagni, D.; Moreau, C.; Scodeggio, M.; Tresse, L.; Zamorani, G.; Adami, C.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Bondi, M.; Bongiorno, A.; Bottini, D.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; de la Torre, S.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; Lemaux, B.; López-Sanjuan, C.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Mellier, Y.; Merighi, R.; Merluzzi, P.; Paltani, S.; Pellò, R.; Pollo, A.; Pozzetti, L.; Scaramella, R.; Tasca, L.; Vergani, D.; Vettolani, G.; Zanichelli, A.; Zucca, E.

    2013-11-01

    Context. Deep representative surveys of galaxies at different epochs are needed to make progress in understanding galaxy evolution. Aims: We describe the completed VIMOS VLT Deep Survey and the final data release of 35 016 galaxies and type-I AGN with measured spectroscopic redshifts covering all epochs up to redshift z ~ 6.7, in areas from 0.142 to 8.7 square degrees, and volumes from 0.5 × 106 to 2 × 107 h-3 Mpc3. Methods: We selected samples of galaxies based solely on their i-band magnitude reaching iAB = 24.75. Spectra were obtained with VIMOS on the ESO-VLT integrating 0.75 h, 4.5 h, and 18 h for the Wide, Deep, and Ultra-Deep nested surveys, respectively. We demonstrate that any "redshift desert" can be crossed successfully using spectra covering 3650 ≤ λ ≤ 9350 Å. A total of 1263 galaxies were again observed independently within the VVDS and from the VIPERS and MASSIV surveys. They were used to establish the redshift measurements reliability, to assess completeness in the VVDS sample, and to provide a weighting scheme taking the survey selection function into account. We describe the main properties of the VVDS samples, and the VVDS is compared to other spectroscopic surveys in the literature. Results: In total we have obtained spectroscopic redshifts for 34 594 galaxies, 422 type-I AGN, and 12 430 Galactic stars. The survey enabled identifying galaxies up to very high redshifts with 4669 redshifts in 1 ≤ zspec ≤ 2, 561 in 2 ≤ zspec ≤ 3, and 468 with zspec > 3, and specific populations like Lyman-α emitters were identified out to z = 6.62. We show that the VVDS occupies a unique place in the parameter space defined by area, depth, redshift coverage, and number of spectra. Conclusions: The VIMOS VLT Deep Survey provides a comprehensive survey of the distant universe, covering all epochs since z ~ 6, or more than 12 Gyr of cosmic time, with a uniform selection, which is the largest such sample to date. A wealth of science results derived from

  19. DISENTANGLING AGN AND STAR FORMATION IN SOFT X-RAYS

    SciTech Connect

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-10-20

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L{sub x,AGN} and L{sub x,SF}) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L{sub x,AGN} and L{sub x,SF} from Monte Carlo simulations. These simulated luminosities agree with L{sub x,AGN} and L{sub x,SF} derived from Chandra imaging analysis within a 3{sigma} confidence level. Using the infrared [Ne II]12.8 {mu}m and [O IV]26 {mu}m lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L{sub x,SF} and L{sub x,AGN} at the 3{sigma} level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  20. Disentangling AGN and Star Formation in Soft X-Rays

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-01-01

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L(sub x,AGN) and L(sub x,SF)) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L(sub x,AGN) and L(sub x,SF))from Monte Carlo simulations. These simulated luminosities agree with L(sub x,AGN) and L(sub x,SF) derived from Chandra imaging analysis within a 3sigma confidence level. Using the infrared [Ne ii]12.8 micron and [O iv]26 micron lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L(sub x,SF) and L(sub x,AGN) at the 3 sigma level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  1. AGN-host galaxy connection: multiwavelength study

    NASA Astrophysics Data System (ADS)

    Pović, M.; Sánchez-Portal, M.; García, A. M. Pérez; Bongiovanni, A.; Cepa, J.; Cepa

    2013-02-01

    The connection between active galactic nuclei (AGN) and their hosts showed to be important for understanding the formation and evolution of active galaxies. Using X-ray and deep optical data, we study how morphology and colours are related to X-ray properties at redshifts z<=2.0 for a sample of > 300 X-ray detected AGN in the Subaru/XMM-Newton Deep Survey (SXDS; Furusawa et al. 2008) and Groth-Westphal Strip (GWS; Pović et al. 2009) fields. We performed our morphological classification using the galSVM code (Huertas-Company et al. 2008), which is a new method that is particularly suited when dealing with high-redshift sources. To separate objects between X-ray unobscured and obscured, we used X-ray hardness ratio HR(0.5-2 keV/2-4.5 keV). Colour-magnitude diagrams were studied in relationship to redshift, morphology, X-ray obscuration, and X-ray-to-optical flux ratio. Around 50% of X-ray detected AGN at z<=2.0 analysed in this work reside in spheroidal and bulge-dominated galaxies, while at least 18% have disk-dominated hosts. This suggests that different mechanisms may be responsible for triggering the nuclear activity. When analysing populations of X-ray detected AGN in both colour-magnitude (CMD) and colour-stellar mass diagrams (Figure 1), the highest number of sources is found to reside in the green valley at redshifts ~ 0.5-1.5. For the first time we studied CMD of these AGN in relation to morphology and X-ray obscuration, finding that they can reside in both early- and late-type hosts, where both morphological types cover similar ranges of X-ray obscuration (Figure 1). Our findings appear to confirm some previous suggestions that X-ray selected AGN residing in the green valley represent a transitional population (e.g. Nandra et al. 2007, Silverman et al. 2008, Treister et al. 2009), quenching star formation by means of different AGN feedback mechanisms and evolving to red-sequence galaxies. More details on analysis and results presented here can be found in

  2. Host Galaxy Properties of BAT Hard X-ray Selected AGN

    NASA Astrophysics Data System (ADS)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa

    2010-07-01

    Surveys of AGN taken in the optical, UV, and soft X-rays miss an important population of obscured AGN only visible in the hard X-rays and mid-IR wavelengths. The SWIFT BAT survey in the hard X-ray range (14-195 keV) has provided a uniquely unbiased sample of 246 AGN unaffected by galactic or circumnuclear absorption [1]. Most of the sources in the survey are bright, Seyfert like AGN's with median redshift of 0.03. Of the AGN, 43% are obscured, type II AGN. We obtained 17 nights of imaging of 90 host galaxies of these AGN in 2008 at the Kitt Peak 2.1 m telescope in the SDSS ugriz filters. For the broad line sources we subtracted the AGN contribution using GALFIT. By comparing our sample of AGN to inactive galaxies in the SDSS, we find that AGN are found in the most massive galaxies and are bluer in color than inactive galaxies of comparable stellar mass. We also find a correlation between the point source optical light and hard X-ray luminosity.

  3. The bulge-disc decomposition of AGN host galaxies

    NASA Astrophysics Data System (ADS)

    Bruce, V. A.; Dunlop, J. S.; Mortlock, A.; Kocevski, D. D.; McGrath, E. J.; Rosario, D. J.

    2016-05-01

    We present the results from a study of the morphologies of moderate luminosity X-ray-selected active galactic nuclei (AGN) host galaxies in comparison to a carefully mass-matched control sample at 0.5 < z < 3 in the CANDELS GOODS-S field. We apply a multiwavelength morphological decomposition analysis to these two samples and report on the differences between the morphologies as fitted from single Sérsic and multiple Sérsic models, and models which include an additional nuclear point-source component. Thus, we are able to compare the widely adopted single Sérsic fits from previous studies to the results from a full morphological decomposition, and address the issue of how biased the inferred properties of AGN hosts are by a potential nuclear contribution from the AGN itself. We find that the AGN hosts are indistinguishable from the general galaxy population except that beyond z ≃ 1.5 they have significantly higher bulge fractions. Even including nuclear sources in our modelling, the probability of this result arising by chance is ˜1 × 10-5, alleviating concerns that previous, purely single Sérsic, analyses of AGN hosts could have been spuriously biased towards higher bulge fractions. This data set also allows us to further probe the physical nature of these point-source components; we find no strong correlation between the point-source component and AGN activity. Our analysis of the bulge and disc fractions of these AGN hosts in comparison to a mass-matched control sample reveals a similar morphological evolutionary track for both the active and non-active populations, providing further evidence in favour of a model where AGN activity is triggered by secular processes.

  4. Possible evidence of destroying small PAH particles by radiation from AGNs

    NASA Astrophysics Data System (ADS)

    Feng, Qi-Chen; Wang, Jing; Wei, Jian-Yan

    2015-02-01

    The issue of destroying small polycyclic aromatic hydrocarbon (PAH) particles by radiation from AGNs is examined through optical narrow-emission line ratios of a sample of type II AGNs. We find that narrow-line ratios [OI]λ6300/Hα and [SII]λ6716, λ6731/Hα have prominent correlations with the PAH 11.3/7.7 ratio in our selected sample of AGNs. Because of the marginal (and in some cases no) dependence of the PAH ratio on the gas metallicity, a possible explanation for the correlations is the destruction of small PAH particles by the hard ionizing field associated with the AGNs.

  5. Obscured AGN at High Redshift

    NASA Technical Reports Server (NTRS)

    Stern, Daniel

    2008-01-01

    This viewgraph presentation reviews the obscured sources of Active Galactic Nuclei (AGN) in the universe at high redshift. The cosmic X-ray background, unified models of AGN and clues to galaxy formation/evolution is the motivation for this study.

  6. Obscured accretion from AGN surveys

    NASA Astrophysics Data System (ADS)

    Vignali, Cristian

    2014-07-01

    Recent models of super-massive black hole (SMBH) and host galaxy joint evolution predict the presence of a key phase where accretion, traced by obscured Active Galactic Nuclei (AGN) emission, is coupled with powerful star formation. Then feedback processes likely self-regulate the SMBH growth and quench the star-formation activity. AGN in this important evolutionary phase have been revealed in the last decade via surveys at different wavelengths. On the one hand, moderate-to-deep X-ray surveys have allowed a systematic search for heavily obscured AGN, up to very high redshifts (z~5). On the other hand, infrared/optical surveys have been invaluable in offering complementary methods to select obscured AGN also in cases where the nuclear X-ray emission below 10 keV is largely hidden to our view. In this review I will present my personal perspective of the field of obscured accretion from AGN surveys.

  7. Starburst or AGN Dominance in Submillimetre-Luminous Candidate AGN?

    NASA Astrophysics Data System (ADS)

    Coppin, Kristen; Pope, Alexandra; Menéndez-Delmestre, Karín; Alexander, David M.; Dunlop, James

    2010-06-01

    It is widely believed that ultraluminous infrared (IR) galaxies and active galactic nuclei (AGN) activity are triggered by galaxy interactions and merging, with the peak of activity occurring at z~2, where submillimetre galaxies are thousands of times more numerous than local ULIRGs. In this evolutionary picture, submillimetre galaxies (SMGs) would host an AGN, which would eventually grow a black hole (BH) strong enough to blow off all of the gas and dust leaving an optically luminous QSO. To probe this evolutionary sequence we have focussed on the `missing link' sources, which demonstrate both strong starburst (SB) and AGN signatures, in order to determine if the SB is the main power source even in SMGs when we have evidence that an AGN is present from their IRAC colours. The best way to determine if a dominant AGN is present is to look for their signatures in the mid-infrared with the Spitzer IRS, since often even deep X-ray observations miss identifying the presence of AGN in heavily dust-obscured SMGs. We present the results of our audit of the energy balance between star-formation and AGN within this special sub-population of SMGs-where the BH has grown appreciably to begin heating the dust emission.

  8. Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations

    SciTech Connect

    Comerford, Julia M.; Pooley, David; Barrows, R. Scott; Greene, Jenny E.; Zakamska, Nadia L.; Madejski, Greg M.; Cooper, Michael C.

    2015-06-19

    Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify. Here we present Chandra/ACIS observations of 12 optically selected dual AGN candidates at $z\\lt 0.34$, where we use the X-rays to identify AGNs. We also present Hubble Space Telescope/Wide Field Camera 3 observations of 10 of these candidates, which reveal any stellar bulges accompanying the AGNs. We discover a dual AGN system with separation ${\\rm \\Delta }x=2.2$ kpc, where the two stellar bulges have coincident [O iii] λ5007 and X-ray sources. This system is an extremely minor merger (460:1) that may include a dwarf galaxy hosting an intermediate mass black hole. We also find six single AGNs, and five systems that are either dual or offset AGNs with separations ${\\rm \\Delta }x\\lt 10$ kpc. Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers, and these AGNs are 10 times more luminous, on average, than the single AGNs in our sample. This hints that major mergers may preferentially trigger higher luminosity AGNs. Further, we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [O III] λ5007 luminosity, on average. Lastly, this could be explained by high densities of gas funneled to galaxy centers during mergers, and emphasizes the need for deeper X-ray observations of dual AGN candidates.

  9. Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations

    DOE PAGES

    Comerford, Julia M.; Pooley, David; Barrows, R. Scott; Greene, Jenny E.; Zakamska, Nadia L.; Madejski, Greg M.; Cooper, Michael C.

    2015-06-19

    Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify. Here we present Chandra/ACIS observations of 12 optically selected dual AGN candidates atmore » $$z\\lt 0.34$$, where we use the X-rays to identify AGNs. We also present Hubble Space Telescope/Wide Field Camera 3 observations of 10 of these candidates, which reveal any stellar bulges accompanying the AGNs. We discover a dual AGN system with separation $${\\rm \\Delta }x=2.2$$ kpc, where the two stellar bulges have coincident [O iii] λ5007 and X-ray sources. This system is an extremely minor merger (460:1) that may include a dwarf galaxy hosting an intermediate mass black hole. We also find six single AGNs, and five systems that are either dual or offset AGNs with separations $${\\rm \\Delta }x\\lt 10$$ kpc. Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers, and these AGNs are 10 times more luminous, on average, than the single AGNs in our sample. This hints that major mergers may preferentially trigger higher luminosity AGNs. Further, we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [O III] λ5007 luminosity, on average. Lastly, this could be explained by high densities of gas funneled to galaxy centers during mergers, and emphasizes the need for deeper X-ray observations of dual AGN candidates.« less

  10. OT1_rmushotz_1: Determining the Bolometric Luminosity of AGN

    NASA Astrophysics Data System (ADS)

    Mushotzky, R.

    2010-07-01

    Determining the bolometric luminosities of AGN is key to understanding their evolution. Uncertainties in the total radiation from AGN translate into uncertainties in their lifetimes, Eddington ratios, mass accretion rates, the form of their radiation, and the predicted black hole spin. However, we still have major problems in measuring this critical quantity. AGN and their host galaxies emit a large fraction of their light in the MIR to FIR, but the origin of this radiation and the connection to the AGN are not well understood. It is not clear whether this radiation is associated with the AGN or with star formation in the galaxy. We propose to use Herschel's unique capabilities to establish the properties of the Swift-BAT all sky sample of local AGN selected at 15-195 keV. We will measure the MIR to FIR (65-500 microns) properties of a complete low-redshift sample (309 objects at z<0.05). The Swift-BAT survey is the least biased all sky survey for AGN with respect to host galaxy properties and obscuration in the line-of-sight, and thus it is superior to optical, IR, or radio surveys for understanding the the nuclear component of the MIR to FIR radiation from active galaxies. The low redshift of our sample, the uniformity of selection, and the large amount of parallel data which have already been obtained (Spitzer, optical, and X-ray spectra, and optical and UV imaging) will allow the most precise determination of the physical origin (AGN versus star formation) of the light. The low redshifts allow the best possible angular resolution for spatially separating star-formation and nuclear components, while only requiring short Herschel exposures. The Herschel BAT survey will provide a comprehensive database for determining the bolometric light of AGN and will be an invaluable reference sample for analyzing higher redshift AGN. It will be a powerful resource for many years to come. We will make it available in a comprehensive and accessible form as rapidly as possible.

  11. Mini-Survey Of SDSS of [OIII] AGN With Swift

    NASA Technical Reports Server (NTRS)

    Angelini, L.; George, I. M.; Hill, J.; Padgett, C. A.; Mushotzky, R. F.

    2008-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work (e.g. Ferrarese and Merritt 2000) strongly suggests every massive galaxy has a central black hole. However, most of these objects either are not radiating or have been very difficult to detect. We are now in the era of large surveys, and the luminosity function (LF) of AGN has been estimated in various ways. In the X-ray band, Chandra and XMM surveys (e.g., Barger et al. 2005; Hasinger, et al. 2005) have revealed that the LF of Hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(x) (at al z). This is seen for all types of AGN, but is stronger for the broad-line objects (e.g., Steffen et al. 2004). In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects (Hao et al. 2005). If, as been suggested, hard X-ray and optical emission line can both be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

  12. The sharpest view of the local AGN population at mid-infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Asmus, Daniel; Hönig, Sebastian F.; Gandhi, Poshak; Smette, Alain; Duschl, Wolfgang J.

    2014-07-01

    We present the largest mid-infrared (MIR) atlas of active galactic nuclei at sub-arcsec 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. All types of AGN are present in the atlas, which also includes 80 per cent of the 9-month BAT AGN sample. Therefore, this atlas and its subsamples are very well-suited for AGN unification studies. A first application of the atlas is the extension of the MIR-X-ray luminosity correlation for AGN.

  13. Mini Survey of SDSS [OIII] AGN with Swift: Testing the Hypothesis that L(sub [OIII]) Traces AGN Luminosity

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work strongly suggests every massive galaxy has a central black hole. However most of these objects either are not radiating or have been very difficult to detect We are now in the era of large surveys, and the luminosity function (LF] of AGN has been estimated in various ways. In the X-ray band. Chandra and XMM surveys have revealed that the LF of hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(sub x) (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects. If as been suggested, hard X ray and optical emission line can both can be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

  14. Detecting AGNs using multi-filter imaging data

    NASA Astrophysics Data System (ADS)

    Dong, Xiaoyi

    2012-05-01

    The purpose of this research project was to develop and test a technique to detect active galactic nuclei, AGNs, using high quality, multi-filter imaging data alone. In order to perform a physically meaningful aperture photometric measurement, we have adapted an image manipulation method - shapelets. shapelets can remove the Point Spread Function (PSF) from an image without the traditional deconvolution in Fourier space. It can therefore be used to adjust the image PSF, i.e., to sharpen the PSF and to make each filter's PSF have the same full width at half maximum (FWHM). shapelets is realized by an IDL based package SHAPELETS, originally designed for studying weak gravitational lensing, and adjusted to suit our application. The primary data we used were selected from the CFHT Legacy Survey Wide Survey field W4. The sample included 6670 galaxies, with u magnitudes ≤ +22 mag, and inclinations ≤ 60°. We applied shapelets to each galaxy for each filter. The result was a shapelets reconstructed image with a 2-D Gaussian PSF with FWHM=3 pixels. We then made relevant photometric measurements on the reconstructed image. In order to calculate distance-dependent parameters such as the galaxy luminosity, we estimated the photometric redshift using an artificial neural network (ANN) with a root mean square (RMS) of 0.025. We designed another neural net to classify the galaxy morphological type based on its photometric properties. The classification was based on Nair and Abraham (2010), and has an accuracy < 2T types. Because galaxy colours alone cannot be used to distinguish AGNs from "normal" galaxies, we also designed a neural net to separate AGN, "normal" , and starforming/starburst galaxies. The accuracy of this classification technique is about 75%. Because our method relies largely on the spatial resolution of the data, we limited our analysis to z ≤ 0.1. The sample contained 1570 galaxies, and we detected 178 AGNs (11.3%), 176 "normal" (11.2%), and 1216

  15. Physics of Gamma Ray Emitting AGN

    NASA Astrophysics Data System (ADS)

    Ojha, Roopesh; Lovell, Jim; Edwards, Philip; Kadler, Matthias; Monitoringteam, Gamma Ray Blazar

    2012-10-01

    The TANAMI VLBI monitoring program, which was granted Large Proposal status from Oct 2009, was set up to capitalize on a 5-10 year window of opportunity provided by the Fermi gamma-ray telescope. TANAMI and its associated components at other wavebands perform simultaneous observations of AGN across the electromagnetic spectrum. Such observations are key to addressing fundamental questions of AGN physics. TANAMI is the only dual-frequency VLBI monitoring program covering the southern third of the sky while Fermi is observing. As such, it is indispensable for tracking parsec-scale jet components and associating their behaviour with changes at high energies. Jet parameters such as speeds and Doppler factors, that are essential inputs to understanding AGN physics, can only be measured with VLBI observations over many years. We request continuation of TANAMI so that the baseline of unique information on kinematics, morphology and the correlation of changes in both with emission at other wavebands, that we have set up can continue to provide important results and indeed produce its highest impact science as we reach critical number of epochs of data on an increasing fraction of our sample.

  16. Morphology of AGN in the Central Kiloparsec

    NASA Astrophysics Data System (ADS)

    Martini, Paul

    Hubble Space Telescope observations of the central kiloparsec of AGN have revealed a wealth of structure, particularly nuclear bars and spirals, that are distinct from analogous features in the disks of spiral galaxies. WFPC2 and NICMOS images of a large sample of AGN observed at high spatial resolution make it possible to quantify the frequency and detailed properties of these structures. Nearly all AGN have nuclear spiral dust lanes in the central kiloparsec, while only a small minority contain nuclear bars. If these nuclear dust spirals trace shocks in the circumnuclear, gaseous disks, they may dissipate sufficient angular momentum to fuel the active nucleus. I would like to thank my collaborators in this project---Rick Pogge, John Mulchaey, and Mike Regan---for allowing me to present this work in advance of publication, as well as Johan Knapen for organizing such an interesting meeting. Support for this work was provided by NASA through grant numbers GO-7867 and GO-8597 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  17. X-Rays and Infrared Selected AGN

    NASA Astrophysics Data System (ADS)

    Kirhakos, S. D.; Steiner, J. E.

    1990-11-01

    RESUMEN. En la busqueda de nucleos activos galacticos (NAG) oscurecidos, seleccionamos una tnuestra de galaxias ernisoras de rayos S infrarrojos, Ia mayoria de las cuales son vistas de perf ii. La 6ptica de la regi6n nuclear de las galaxias seleccionadas revelan que el 76% de ellas muestran lineas de emisi5n La clasificaci6n de los es- pectros de acuerdo a los anchos y a la intensidad de cocientes de lineas muestran que existen 34 NAG, 34 objetos de tipo de transici6n y 34 galaxias de la regi6n con nucleos de tipo regi6n H II. Entre los NAG, 3 son del tipo Seyfert I y las otras son del tipo 2. Sugerimos que los objetos identificados como NAG de llneas angostas son objetos tipo Seyfert I oscurecidos ABSTRACT. Looking for obscured active galactic nuclei (AGN), we selected a sample of infrarediX-rays emitting galaxies, mos"t of which are seen as edge-on. Optical spectroscopy of the nuclear region of the selected galaxies revealed that 76 % of them show emission l 'nes. Classification of the spectra according to the widths and line intensity ratios shows that there are 34 AGN, 34 transition type objects and 43 nuclear HIl-like region galaxies. Among the AGN, three are Seyfert type 1 and the others are type 2 objects. We suggest that the objects identified as narrow line AGN are obscured Seyfert 1. o'L : GALAXIES-ACTIVE - X-RAY S-GENERAL

  18. Mini-Survey of SDSS OIII AGN with Swift

    NASA Technical Reports Server (NTRS)

    Angelina, Lorella; George, Ian

    2007-01-01

    There is a common wisdom that every massive galaxy has a massive block hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low Lx (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of (optically-selected samples) shows no such break and no differences between narrow and broad-line objects. Assuming both hard X-ray and [OIII] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a mini-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([OIII]) to check the relation with the Lx observed with Swift.

  19. THE ORIGIN OF DOUBLE-PEAKED NARROW LINES IN ACTIVE GALACTIC NUCLEI. I. VERY LARGE ARRAY DETECTIONS OF DUAL AGNs AND AGN OUTFLOWS

    SciTech Connect

    Müller-Sánchez, F.; Comerford, J. M.; Nevin, R.; Barrows, R. S.; Cooper, M. C.; Greene, J. E.

    2015-11-10

    We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have 2 optical AGN emission components separated by >0.″2, and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without follow-up observations, the sources of the double-peaked narrow emission lines are uncertain, and may be produced by kiloparsec-scale separation dual active supermassive black holes, AGN outflows, or disk rotation. In this work, we propose a new methodology to characterize double-peaked narrow emission line galaxies based on optical long-slit spectroscopy and high-resolution multi-band Very Large Array observations. The nature of the radio emission in the sample galaxies is varied. Of the 18 galaxies, we detect 2 compact flat-spectrum radio cores with projected spatial separations on the sky between 0.6 and 1.6 kpc in 3 galaxies: J1023+3243, J1158+3231, and J1623+0808. The two radio sources are spatially coincident with the two optical components of ionized gas with AGN-like line ratios, which confirms the presence of dual AGNs in these three galaxies. Dual AGNs account for only ∼15% (3/18) of the double-peaked AGNs in our sample. Gas kinematics produce ∼75% (13/18) of the double-peaked narrow emission lines, distributed in the following way: seven AGN wind-driven outflows, five radio-jet driven outflows, and one rotating narrow-line region. The remaining 10% (2/18) are ambiguous cases. Our method demonstrates the power of spatially resolved spectroscopy and high-resolution radio observations for the identification of AGN outflows and AGN pairs with angular separations as small as 0.″18.

  20. SED and Emission Line Properties of Red 2MASS AGN

    NASA Astrophysics Data System (ADS)

    Kuraszkiewicz, Joanna; Wilkes, Belinda J.; Schmidt, Gary; Ghosh, Himel

    2009-09-01

    Radio and far-IR surveys, and modeling of the cosmic X-ray background suggest that a large population of obscured AGN has been missed by traditional, optical surveys. The Two Micron All-Sky Survey (2MASS) has revealed a large population (surface density comparable to that of optically selected AGN with Ks<14.5mag) of mostly nearby (median z=0.25), red, moderately obscured AGN, among which 75% are previously unidentified emission-line AGN, with 85% showing broad emission lines. We present the SED and emission line properties of 44 such red (J-Ks>2) 2MASS AGN observed with Chandra. They lie at z<0.37, span a full range of spectral types (Type 1, intermediate, Type 2),Ks-to-X-ray slopes, and polarization (<13%). Their IR-to-X-ray spectral energy distributions (SEDs) are red in the near-IR/opt/UV showing little or no blue bump. The optical colors are affected by reddening, host galaxy emission, redshift, and in few, highly polarized objects, also by scattered AGN light. The levels of obscuration obtained from optical, X-rays, and far-IR imply N_H AGN light. PCA analysis of the IR-X-ray SED and emission line properties shows that, while obscuration/inclination is important, the dominant cause of variance in the sample (eigenvector 1) is the L/L_{edd} ratio (perhaps because the red near-IR selection limits the range of inclination/obscuration values in our sample). This analysis also distinguishes two sources of obscuration: the host galaxy and circumnuclear absorption.

  1. X-Ray Absorption, Nuclear Infrared Emission, and Dust Covering Factors of AGNs: Testing Unification Schemes

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X.; Asensio Ramos, A.; Watson, M. G.; Blain, A.; Caccianiga, A.; Ballo, L.; Braito, V.; Ramos Almeida, C.

    2016-03-01

    We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2-10 keV luminosities between 1042 and 1046 erg s-1, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1-20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f2 than type 1 AGNs. Nevertheless, ˜20% of type 1 AGNs have tori with large covering factors, while ˜23%-28% of type 2 AGNs have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f2 increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f2 determine the optical appearance of an AGN and control the shape of the rest-frame ˜1-20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.

  2. Three years of Swift/BAT Survey of AGN: Reconciling Theory and Observations?

    SciTech Connect

    Burlon, D.; Ajello, M.; Greiner, J.; Comastri, A.; Merloni, A.; Gehrels, N.; /NASA, Goddard

    2011-02-07

    It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still escapes detection. We derive and analyze the absorption distribution using a complete sample of AGN detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGN represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGN is 20{sub -6}{sup +9}%. We proved for the first time (also in the BAT band) that the anti-correlation of the fraction of absorbed AGN and luminosity it tightly connected to the different behavior of the luminosity functions (XLFs) of absorbed and unabsorbed AGN. This points towards a difference between the two subsamples of objects with absorbed AGN being, on average, intrinsically less luminous than unobscured ones. Moreover the XLFs show that the fraction of obscured AGN might also decrease at very low luminosity. This can be successfully interpreted in the framework of a disk cloud outflow scenario as the disappearance of the obscuring region below a critical luminosity. Our results are discussed in the framework of population synthesis models and the origin of the Cosmic X-ray Background.

  3. Using AGN to Observe the Growth of the Cosmic Web

    NASA Astrophysics Data System (ADS)

    Murray, S.; Jones, C.; Forman, W.; Kenter, A.; Vihklinin, A.; Markevitch, M.; Brand, K.; Jannuzi, B.; Kochanek, C.; Eisenstein, D.

    We present X-ray and optical observations of the contiguous 9 3 sq deg XBootes survey made with the ACIS instrument on Chandra The X-ray survey consists of 126 5ksec pointings that achieve a sensitivity of about 4 times10 -15 erg cm -2 s -1 in the 0 5--7 keV band At this sensitivity limit we detect 4642 X-ray sources As part of the AGES galaxy survey in the Bootes region Kochanek et al 2005 we have obtained 1800 redshifts of the X-ray selected objects most of which are AGN yielding a density of sim150 AGN per square degree The mean AGN redshift is 1 3 with the distribution extending to z 4 We have analyzed the spatial distribution of the X-ray selected AGN and compared this to the distribution of the sim20000 AGES galaxies To z sim0 7 the limit of galaxy sample the galaxies and AGN both trace the same structures and show the same web of voids and filaments At larger redshifts the X-ray AGN continue to show the characteristic structure of voids and filaments Quantitatively we computed the spatial 2-point correlation function for the X-ray selected AGN and find that the correlation length r 0 simeq6 4 h -1 Mpc and the exponent gamma simeq-1 7 of the correlation function are similar to the canonical values derived for galaxies In addition we have compared the correlation function in several redshift intervals and find that the correlation length is approximately constant to z sim1 5

  4. AGN are cooler than you think: the intrinsic far-IR emission from QSOs

    NASA Astrophysics Data System (ADS)

    Symeonidis, M.; Giblin, B. M.; Page, M. J.; Pearson, C.; Bendo, G.; Seymour, N.; Oliver, S. J.

    2016-06-01

    We present an intrinsic AGN spectral energy distribution (SED) extending from the optical to the submm, derived with a sample of unobscured, optically luminous (νLν,5100 > 1043.5 erg s-1) QSOs at z < 0.18 from the Palomar Green survey. The intrinsic AGN SED was computed by removing the contribution from stars using the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature in the QSOs' mid-IR spectra; the 1σ uncertainty on the SED ranges between 12 and 45 per cent as a function of wavelength and is a combination of PAH flux measurement errors and the uncertainties related to the conversion between PAH luminosity and star-forming luminosity. Longwards of 20 μm, the shape of the intrinsic AGN SED is independent of the AGN power indicating that our template should be applicable to all systems hosting luminous AGN (νLν, 5100 or L_X(2-10 keV) ≳ 1043.5 erg s-1). We note that for our sample of luminous QSOs, the average AGN emission is at least as high as, and mostly higher than, the total stellar powered emission at all wavelengths from the optical to the submm. This implies that in many galaxies hosting powerful AGN, there is no `safe' broad-band photometric observation (at λ < 1000 μm) which can be used in calculating star formation rates without subtracting the AGN contribution. Roughly, the AGN contribution may be ignored only if the intrinsic AGN luminosity at 5100 AA is at least a factor of 4 smaller than the total infrared luminosity (LIR, 8-1000 μm) of the galaxy. Finally, we examine the implication of our work in statistical studies of star formation in AGN host galaxies.

  5. The INTEGRAL/IBIS AGN catalogue: an update

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Landi, R.; Molina, M.; Bassani, L.; Bazzano, A.; Bird, A. J.; Ubertini, P.

    2016-07-01

    In the most recent IBIS survey based on observations performed during the first 1000 orbits of INTEGRAL, are listed 363 high-energy emitters firmly associated with AGN, 107 of which are reported here for the first time. We have used X-ray data to image the IBIS 90 per cent error circle of all the AGN in the sample of 107, in order to obtain the correct X-ray counterparts, locate them with arcsec accuracy and therefore pinpoint the correct optical counterparts. This procedure has led to the optical and spectral characterization of the entire sample. This new set consists of 34 broad line or type 1 AGN, 47 narrow line or type 2 AGN, 18 blazars and 8 sources of unknown class. These eight sources have been associated with AGN from their positional coincidence with 2MASX/Radio/X-ray sources. Seven high-energy emitters have been included since they are considered to be good AGN candidates. Spectral analysis has been already performed on 55 objects and the results from the most recent and/or best statistical measurements have been collected. For the remaining 52 sources, we report the spectral analysis for the first time in this work. We have been able to obtain the full X-ray coverage of the sample making use of data from Swift/XRT, XMM-Newton and NuSTAR. In addition to the spectral characterization of the entire sample, this analysis has enabled us to identify peculiar sources and by comparing different data sets, highlight flux variability in the 2-10 keV and 20-40 keV bands.

  6. The 60 Month All-Sky Burst Alert Telescope Survey of Active Galactic Nucleus and the Anisotropy of Nearby AGNs

    NASA Technical Reports Server (NTRS)

    Ajello, M.; Alexander, D. M.; Greiner, J.; Madejeski, G. M.; Gehrels, N.; Burlon, D.

    2014-01-01

    Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of approx. 2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent approx. 5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to approx. 10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9(+4.1/-2.9)× 10(exp -5)/cubic Mpc for objects with a de-absorbed luminosity larger than 2 × 10(exp 42) erg / s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (much < 85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions..

  7. Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Swinbank, A. M.

    2014-07-01

    We present integral field unit observations covering the [O III]λλ4959, 5007 and Hβ emission lines of 16 z < 0.2 type 2 active galactic nuclei (AGN). Our targets are selected from a well-constrained parent sample of ≈24 000 AGN so that we can place our observations into the context of the overall AGN population. Our targets are radio quiet with star formation rates (SFRs; ≲[10-100] M⊙ yr-1) that are consistent with normal star-forming galaxies. We decouple the kinematics of galaxy dynamics and mergers from outflows. We find high-velocity ionized gas (velocity widths ≈600-1500 km s-1; maximum velocities ≤1700 km s-1) with observed spatial extents of ≳(6-16) kpc in all targets and observe signatures of spherical outflows and bi-polar superbubbles. We show that our targets are representative of z < 0.2, luminous (i.e. L[O III] > 1041.7 erg s-1) type 2 AGN and that ionized outflows are not only common but also in ≥70 per cent (3σ confidence) of cases, they are extended over kiloparsec scales. Our study demonstrates that galaxy-wide energetic outflows are not confined to the most extreme star-forming galaxies or radio-luminous AGN; however, there may be a higher incidence of the most extreme outflow velocities in quasars hosted in ultraluminous infrared galaxies. Both star formation and AGN activity appear to be energetically viable to drive the outflows and we find no definitive evidence that favours one process over the other. Although highly uncertain, we derive mass outflow rates (typically ≈10 times the SFRs), kinetic energies (≈0.5-10 per cent of LAGN) and momentum rates (typically ≳10-20 × LAGN/c) consistent with theoretical models that predict AGN-driven outflows play a significant role in shaping the evolution of galaxies.

  8. Compton thick AGN in the XMM-COSMOS survey

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Ranalli, P.; Georgantopoulos, I.; Georgakakis, A.; Delvecchio, I.; Akylas, T.; Berta, S.; Bongiorno, A.; Brusa, M.; Cappelluti, N.; Civano, F.; Comastri, A.; Gilli, R.; Gruppioni, C.; Hasinger, G.; Iwasawa, K.; Koekemoer, A.; Lusso, E.; Marchesi, S.; Mainieri, V.; Merloni, A.; Mignoli, M.; Piconcelli, E.; Pozzi, F.; Rosario, D. J.; Salvato, M.; Silverman, J.; Trakhtenbrot, B.; Vignali, C.; Zamorani, G.

    2015-01-01

    Heavily obscured, Compton thick (CT, NH> 1024 cm-2) active galactic nuclei (AGN) may represent an important phase in AGN/galaxy co-evolution and are expected to provide a significant contribution to the cosmic X-ray background at its peak. However, unambiguously identifying CT AGN beyond the local Universe is a challenging task even in the deepest X-ray surveys, and given the expected low spatial density of these sources in the 2-10 keV band, large area surveys are needed to collect sizable samples. Through direct X-ray spectra analysis, we selected 39 heavily obscured AGN (NH>3 × 1023 cm-2) at bright X-ray fluxes (F2-10 ≳ 10-14 erg s-1 cm-2) in the 2 deg2 XMM-COSMOS survey. After selecting CT AGN based on the fit of a simple absorbed two power law model to the shallow XMM-Newton data, the presence of bona fide CT AGN was confirmed in 80% of the sources using deeper Chandra data and more complex models. The final sample comprises ten CT AGN (six of them also have a detected Fe Kα line with EW ~ 1 keV), spanning a wide range of redshifts (z ~ 0.1-2.5) and luminosity (L2-10 ~ 1043.5-1045 erg s-1) and is complemented by 29 heavily obscured AGN spanning the same redshift and luminosity range. We collected the rich multi-wavelength information available for all these sources, in order to study the distribution of super massive black hole and host properties, such as black hole mass (MBH), Eddington ratio (λEdd), stellar mass (M∗), specific star formation rate (sSFR) in comparison with a sample of unobscured AGN. We find that highly obscured sources tend to have significantly smaller MBH and higher λEdd with respect to unobscured sources, while a weaker evolution in M∗ is observed. The sSFR of highly obscured sources is consistent with the one observed in the main sequence of star forming galaxies, at all redshifts. We also present and briefly discuss optical spectra, broadband spectral energy distribution (SED) and morphology for the sample of ten CT AGN. Both

  9. IR properties of AGN and SB

    NASA Astrophysics Data System (ADS)

    Talezade Lari, M. H.; Davoudifar, P.; Mickaelian, A. M.

    2016-09-01

    Through multi-wavelength flux ratios it is possible to detect AGN and Star-burst Galaxies. Techniques of detecting extragalactic objects as well as AGN are studied in different wavelengths (X-Ray, Radio and IR). Specification of AGN as IR and radio sources is discussed. IR catalogues of 2MASS and WISE were used to study the interrelationship between interactions/merging, starburst and AGN phenomena.

  10. Optical variability of the Kepler AGN

    NASA Astrophysics Data System (ADS)

    Edelson, Rick

    2014-01-01

    Kepler has opened a new era for the study of AGN optical variability, producing light curves with ~0.1% errors (for a ~15th magnitude source), 30 min sampling, >90% duty cycle and durations of years. Thanks to an intensive identification campaign, the number of Seyfert 1s/quasars monitored by Kepler rose from just one (Zw 229-15) in the first year to 37 by the time of May 2013 reaction wheel failure. We measured the optical power spectral density (PSD) functions of these Kepler AGN finding that that on timescales of ~6 hr to 1 month, the PSDs are typically well-fitted with a slop of ~-3, steeper than seen in the X-rays. In a few sources there is also evidence for a flattening at the longest timescales. We also find a broad correlation between rms variability and flux level. These results broadly support the model in which the optical fluctuations are due to vicious instabilities in the accretion disk. I will also present the light curve for W2R1926+42, the only rapidly variable BL Lac object known to be monitored by Kepler. With data covering over a year and sampling rates of 1-30 min, this may be the information-richest AGN light curve ever gathered at any wavelength. The PSD appears to bend from a slope of -2.6 to -1.2 on a ~7 hr timescale, but fits are formally unacceptable. These data indicate that the phenomenon of blazar "microvariability" (sporadic variations on timescales shorter than the ~12 hour window available from the ground) actually results from a combination of rapid, powerful variability interspersed with longer, relatively quiescent periods.

  11. Interpreting the IR SED of z~0.3-2.8 IR-Luminous Galaxies and AGN Using Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Roebuck, Eric John; Sajina, Anna; Hayward, Christopher C.; Pope, Alexandra; Kirkpatrick, Allison; Hernquist, Lars E.; Yan, Lin

    2016-01-01

    We use three-dimensional hydrodynamical galaxy merger simulations to further investigate the nature of a sample of 342 24 μm-selected (ultra) luminous infrared galaxies at z~0.3-2.8. All of our sources have low-resolution Spitzer/IRS spectra -- the largest such sample outside the local universe. These spectra allow us to determine that our sample consists of a mixture of star forming galaxies (SFGs), AGN, and composites. We address the question of how well do empirical IR AGN fraction estimates trace the intrinsic AGN fraction (i.e. the AGN-to-total power in the galaxy prior to dust re-processing), including how they relate to galaxy properties such as merger stage, dust/gas content, and star formation rates. We do this by fitting the observed SEDs of our sample with theoretical SEDs based on GADGET hydrodynamic merger simulations additionally processed through the SUNRISE radiative transfer code. We additionally investigate systematic uncertainties associated with these quantities using the goodness of fits to our model library. The key findings are: 1) our simulation-based fits are in broad agreement with the empirical model-based fits, 2) much of the AGN fraction of LIR is missed if the AGN's contribution to heating the host galaxy dust is not accounted for, and 3) the IR AGN fraction traces the intrinsic AGN fraction up to the coalescence stage, however may underestimate the intrinsic AGN fraction post coalescence.

  12. AGN identification: what lies ahead

    NASA Astrophysics Data System (ADS)

    Fotopoulou, Sotiria

    2016-08-01

    Classification has been one the first concerns of modern astronomy, starting from stars sorted in the famous Harvard classification system and promptly followed by the morphological classification of galaxies by none other than Edwin Hubble himself (Hubble 1926). Both classification schema are essentially connected to the physics of the objects reflecting the temperature for stars and e.g. the age of the star population for galaxies. Systematic observations of galaxies have revealed the intriguing class of Active Galactic Nuclei (AGN), objects of tremendous radiation that do not share the same properties of what we now call normal galaxies. Observations have led to the definition of distinct and somewhat arbitrary categories (Seyfert galaxies, quasars, QSO, radio AGN, etc), essentially rediscovering the many faces of the same phenomenon, up until the unification of AGN (Antonucci 1993, Urry and Padovani 1995). Even after the realization that all AGN have the same engine powering their amazing radiation, astronomers are still using and refining the selection criteria within their favorite electromagnetic range in the hope to better understand the impact of the AGN phenomenon in the greater context of galaxy evolution. In the dawn of Big Data astronomy we find ourselves equipped with new tools. I will present the prospects of machine learning methods in better understanding the AGN population. Namely, I will show results from supervised learning algorithms whereby a labeled training set is used to amalgamate decision tree(s) (Fotopoulou et al., 2016) or neural network(s), and unsupervised learning where the algorithm performs clustering analysis of the full dataset in a multidimensional space identifying clusters of objects sharing potentially the same physical properties (Fotopoulou in prep.).

  13. The search for red AGN with 2MASS

    NASA Technical Reports Server (NTRS)

    Cutri, R. M.; Nelson, B. O.; Kirkpatrick, J. D.; Huchra, J. P.; Smith, P. S.

    2001-01-01

    We present the results of a simple, highly efficient 2MASS color-based survey that has already discovered 140 previously unknown red AGN and QSOs. These objects are near-infrared-bright and relatively nearby; the media redshift of the sample is z=0.25, and all but two have z<0.7.

  14. The Role of Environment in Fueling Seyfert AGN

    NASA Astrophysics Data System (ADS)

    Hicks, Erin Kathleen Strobel

    2015-08-01

    We consider the role of environment in fueling of Seyfert AGN through a combined analysis of Hubble Space Telescope images and integral field spectroscopy of the ISM in a sample of local AGN. Using visible and near-infrared Hubble Space Telescope images and color maps of over a 100 galaxies we determine the distribution of the cold ISM, as traced by dust. We also measure the two-dimensional distribution and kinematics of the molecular gas, traced by H2 1-0 S(1) emission at 2.12 μm, down to scales of tens of parsecs using OSIRIS at Keck and SINFONI on VLT for a subset of approximately 20 of these galaxies. Informed by these kinematic measurements of the ISM we classify the nuclear dust morphologies of the full sample of galaxies and interpret the significance of these morphologies in terms of inflow. Our relatively small precursor sample (Hicks et al. 2009, Davies et al. 2014) hinted at a connection between the host galaxy environment and the primary mechanism driving gas inward such that fueling of AGN in isolated galaxies occurs primarily via secular processes (e.g. nuclear spirals) and galaxies in groups of 10-15 members via accretion of external gas. Using our expanded sample that now has the ability to reveal statistically significant trends we explore the potential influence of the galaxy environment on the fueling of Seyfert AGN.

  15. AGN Survey to characterize the clumpy torus using FORCAST

    NASA Astrophysics Data System (ADS)

    Lopez-Rodriguez, Enrique

    2015-10-01

    A geometrically and optically thick torus of gas and dust obscures the black hole and accretion disk in active galactic nuclei (AGN) in some lines of sight. One of the most important question that still remain uncertain is: How do the properties, such as torus geometry and distribution of clumps, of the torus depend on the AGN luminosity and/or activity class? Infrared (IR) observations are essential to these investigations as the torus intercepts and re-radiates (peaking within 30-40 um) a substantial amount of flux from the central engine. Near-IR (NIR) and mid-IR (MIR) observations from the ground have been key to advance our knowledge in this field. However, the atmosphere is opaque to the 30-40 um range and observations are impossible from ground-based telescopes. FORCAST presents a unique opportunity to explore AGN, providing the best angular resolution observations within the 30-40 um range for the current suite of instruments. From our analysis using Cycle 2 observations, we found that FORCAST provides the largest constraining power of the clumpy torus models in the suggested wavelength range. We therefore request an AGN Survey using FORCAST of snapshot imaging observations of a flux-limited (>500 mJy at 37.1 um) sample of 23 Seyfert galaxies with existing high-angular resolution MIR spectra observed on 8-m class telescopes. Using the FORCAST data requested here in combination with already acquired NIR and MIR data, we will have an unprecedentedly homogeneous AGN sample of IR (1-40 um) SED at the largest spatial-resolution, which yield to a better knowledge of the torus structure in the AGN unified model.

  16. Tracing outflows in the AGN forbidden region with SINFONI

    NASA Astrophysics Data System (ADS)

    Kakkad, D.; Mainieri, V.; Padovani, P.; Cresci, G.; Husemann, B.; Carniani, S.; Brusa, M.; Lamastra, A.; Lanzuisi, G.; Piconcelli, E.; Schramm, M.

    2016-08-01

    Context. Active galactic nucleus (AGN) driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were at their maximum. Radiatively driven outflows are therefore believed to be common during this epoch. Aims: We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially resolved kinematics of the [O iii] λ5007 line in two targets which reveal the morphology and spatial extension of the outflows. Methods: We present SINFONI observations in the J band and the H + K band of five AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km s-1) and kiloparsec scale extended ionized outflows in at least three of our targets, using [O iii] λ5007 line kinematics tracing the AGN narrow line region. We estimate the total mass of the outflow, the mass outflow rate, and the kinetic power of the outflows based on theoretical models and report on the uncertainties associated with them. Results: We find mass outflow rates of ~1-10 M⊙/yr for the sample presented in this paper. Based on the high star formation rates of the host galaxies, the observed outflow kinetic power, and the expected power due to the AGN, we infer that both star formation and AGN radiation could be the dominant source for the outflows. The outflow models suffer from large uncertainties, hence we call for further detailed observations for an accurate determination of the outflow properties to confirm the exact source of these outflows.

  17. Broad emission lines variability: a window into the heart of AGN

    NASA Astrophysics Data System (ADS)

    Ilic, Dragana; Popovic, Luka C.; Shapovalova, Alla I.; Afanasiev, V. L.; Chavushyan, V. H.; Burenkov, A.; Kollatschny, W.; Kovacevic, A.

    2016-08-01

    The broad emission lines of active galactic nuclei (AGN) are known to vary both in flux and shape, and are often showing very complex line profiles. They can give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. The BLR is close to the supermassive black hole in AGN and may hold basic information about the formation and fueling of AGN.Here we summarize the results of the line and continuum variability of a sample of broad line AGN, obtained with the long-term optical monitoring campaign performed with telescopes of SAO (Russia), OAGH and OAN-SPM (Mexico), and Calar Alto (Spain). We monitored different type of broad line AGN (double-peaked, radio loud and radio quiet, NLSy1 and a supermassive binary black hole candidate) which show different variability characteristics that can be explained by different physical properties in BLR.

  18. The dependence of X-ray AGN activity on host galaxy properties and environment

    NASA Astrophysics Data System (ADS)

    Tasse, C.; Röttgering, H.; Best, P. N.

    2011-01-01

    There is mounting evidence that active galactic nuclei (AGN) selected through optical emission lines or radio luminosities comprise two distinct AGN populations, whose activity is triggered by different processes. In two previous papers, we studied the host galaxies and environment of radio-loud AGN. In this third paper we study the properties of a sample of Type-2 AGN that were selected on the basis of their [2-10] keV X-ray luminosity. We find that the X-ray luminosity function is in good agreement with previous studies and that the fraction of galaxies hosting an X-ray AGN is a strong function of the stellar mass of the host galaxy. The shape of this fraction-mass relation is similar to the fraction of galaxies that are emission-line AGN, while it differs significantly from the relation observed for radio-selected AGN. The AGN in our sample tend to be located in underdense environments where galaxy mergers and interactions are likely to occur. For all host galaxy masses, the Type-2 AGN display a strong infrared excess at short (~3.5 μm) wavelengths, suggesting the presence of hot dust possibly associated with a hot dusty torus. These results add weight to the belief that the X-ray selection criteria identifies a population of AGN similar to the emission-line selected population but distinct from the radio population at high masses. Appendix A is only available in electronic form at http://www.aanda.org

  19. Multiwavelength AGN Surveys and Studies (IAU S304)

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.; Sanders, David B.

    2014-08-01

    1. Historical surveys: spectral and colorimetric surveys for AGN, surveys for UV-excess galaxies; 2. AGN from IR/submm surveys: 2MASS, IRAS, ISO, AKARI, SCUBA, SST, WISE, Herschel; 3. AGN from radio/mm surveys: NVSS, FIRST, ALMA, Planck, and others; 4. AGN from X-ray/gamma-ray surveys: ROSAT, ASCA, BeppoSAX, Chandra, XMM, INTEGRAL, Fermi, HESS, MAGIC, VERITAS, NuSTAR; 5. Multiwavelength AGN surveys, AGN statistics and cross-correlation of multiwavelength surveys; 6. Unification and other models of AGN, accretion modes, understanding of the structure of nearby AGN from IFUs on VLT and other telescopes; 7. AGN feedback in galaxies and clusters, AGN host galaxies and the AGN environments; 8. Binary AGN and Merging Super-Massive Black Holes; 9. Study of unique AGN, AGN variability and the Phenomena of Activity; 10. Future large projects; Author index.

  20. The most obscured AGN in the COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Perna, M.; Delvecchio, I.; Berta, S.; Brusa, M.; Cappelluti, N.; Comastri, A.; Gilli, R.; Gruppioni, C.; Mignoli, M.; Pozzi, F.; Vietri, G.; Vignali, C.; Zamorani, G.

    2015-06-01

    Highly obscured active galactic nuclei (AGN) are common in nearby galaxies, but are difficult to observe beyond the local Universe, where they are expected to significantly contribute to the black hole accretion rate density. Furthermore, Compton-thick (CT) absorbers (NH ≳ 1024 cm-2) suppress even the hard X-ray (2-10 keV) AGN nuclear emission, and therefore the column density distribution above 1024 cm-2 is largely unknown. We present the identification and multi-wavelength properties of a heavily obscured (NH ≳ 1025 cm-2), intrinsically luminous (L2-10 > 1044 erg s-1) AGN at z = 0.353 in the COSMOS field. Several independent indicators, such as the shape of the X-ray spectrum, the decomposition of the spectral energy distribution and X-ray/[NeV] and X-ray/6 μm luminosity ratios, agree on the fact that the nuclear emission must be suppressed by a ≳1025 cm-2 column density. The host galaxy properties show that this highly obscured AGN is hosted in a massive star-forming galaxy, showing a barred morphology, which is known to correlate with the presence of CT absorbers. Finally, asymmetric and blueshifted components in several optical high-ionization emission lines indicate the presence of a galactic outflow, possibly driven by the intense AGN activity (LBol/LEdd = 0.3-0.5). Such highly obscured, highly accreting AGN are intrinsically very rare at low redshift, whereas they are expected to be much more common at the peak of the star formation and BH accretion history, at z ~ 2-3. We demonstrate that a fully multi-wavelength approach can recover a sizable sample of such peculiar sources in large and deep surveys such as COSMOS.

  1. DUAL SUPERMASSIVE BLACK HOLE CANDIDATES IN THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Comerford, Julia M.; Schluns, Kyle; Greene, Jenny E.; Cool, Richard J.

    2013-11-01

    Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z < 0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z = 0.25 to z = 0.7 by a factor of ∼6 (from 2/70 to 16/91, or 2.9{sup +3.6}{sub -1.9}% to 18{sup +5}{sub -5}%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ∼3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9{sup +3}{sub -2}% to 29{sub -19}{sup +26}%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.

  2. The Host Galaxy Properties of Variability Selected AGN in the Pan-STARRS1 Medium Deep Survey

    NASA Astrophysics Data System (ADS)

    Heinis, S.; Gezari, S.; Kumar, S.; Burgett, W. S.; Flewelling, H.; Huber, M. E.; Kaiser, N.; Wainscoat, R. J.; Waters, C.

    2016-07-01

    We study the properties of 975 active galactic nuclei (AGNs) selected by variability in the Pan-STARRS1 Medium deep Survey. Using complementary multi-wavelength data from the ultraviolet to the far-infrared, we use spectral energy distribution fitting to determine the AGN and host properties at z < 1 and compare to a well-matched control sample. We confirm the trend previously observed: that the variability amplitude decreases with AGN luminosity, but we also observe that the slope of this relation steepens with wavelength, resulting in a “redder when brighter” trend at low luminosities. Our results show that AGNs are hosted by more massive hosts than control sample galaxies, while the rest frame dust-corrected NUV - r color distribution of AGN hosts is similar to control galaxies. We find a positive correlation between the AGN luminosity and star formation rate (SFR), independent of redshift. AGN hosts populate the entire range of SFRs within and outside of the Main Sequence of star-forming galaxies. Comparing the distribution of AGN hosts and control galaxies, we show that AGN hosts are less likely to be hosted by quiescent galaxies and more likely to be hosted by Main Sequence or starburst galaxies.

  3. Radio-AGN feedback: when the little ones were monsters

    NASA Astrophysics Data System (ADS)

    Williams, W. L.; Röttgering, H. J. A.

    2015-06-01

    We present a study of the evolution of the fraction of radio-loud active galactic nuclei (AGN) as a function of their host stellar mass. We make use of two samples of radio galaxies: one in the local Universe, 0.01 < z ≤ 0.3, using a combined SDSS-NVSS (Sloan Digital Sky Survey NRAO Very Large Array Sky Survey) sample and the other at higher redshifts, 0.5 < z ≤ 2, constructed from the VLA-COSMOS_DEEP Radio Survey at 1.4 GHz and a Ks-selected catalogue of the COSMOS/UltraVISTA field. We observe an increase of more than an order of magnitude in the fraction of lower mass galaxies (M* < 1010.75 M⊙) which host radio-loud AGN with radio powers P1.4 GHz > 1024 W Hz-1 at z ˜ 1-2 while the radio-loud fraction for higher mass galaxies (M* > 1011.25 M⊙) remains the same. We argue that this increase is driven largely by the increase in cold or radiative mode accretion with increasing cold gas supply at earlier epochs. The increasing population of low-mass radio-loud AGN can thus explain the upturn in the radio luminosity function at high redshift which is important for understanding the impact of AGN feedback in galaxy evolution.

  4. Disentangling star formation and AGN activity in powerful infrared luminous radio galaxies at 1 < z < 4

    NASA Astrophysics Data System (ADS)

    Drouart, G.; Rocca-Volmerange, B.; De Breuck, C.; Fioc, M.; Lehnert, M.; Seymour, N.; Stern, D.; Vernet, J.

    2016-09-01

    High-redshift radio galaxies present signs of both star formation and AGN activity, making them ideal candidates to investigate the connection and coevolution of AGN and star formation in the progenitors of present-day massive galaxies. We make use of a sample of 11 powerful radio galaxies spanning 1 AGN and star formation by combining the galaxy evolution code PÉGASE.3 with an AGN torus model. We find that three components are necessary to reproduce the observed SEDs: an evolved and massive stellar component, a submm bright young starburst, and an AGN torus. We find that powerful radio galaxies form at very high-redshift, but experience episodic and important growth at 1 AGN bolometric luminosity. Moreover, we find that AGN scattered light have a very limited impact on broad-band SED fitting on our sample. Finally, our analysis also suggests a wide range in origins for the observed star formation,which we partially constrain for some sources.

  5. The KMOS AGN Survey at High redshift (KASHz): the prevalence and drivers of ionized outflows in the host galaxies of X-ray AGN

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Stott, J. P.; Swinbank, A. M.; Arumugam, V.; Bauer, F. E.; Bower, R. G.; Bunker, A. J.; Sharples, R. M.

    2016-02-01

    We present the first results from the KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≳ 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (L2-10 keV = 1042-1045 erg s-1), for which we observed [O III] (z ≈ 1.1-1.7) or Hα emission (z ≈ 0.6-1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O III] targets, ≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths ≳600 km s-1). The most luminous half (i.e. LX > 6 × 1043 erg s-1) have a ≳2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASHz sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z < 0.4 AGN. This implies little evolution in the prevalence of ionized outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in average star formation rates over this redshift range. Furthermore, we compare our Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to ≈10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.

  6. IRAS observations of AGN candidates at low flux levels

    NASA Technical Reports Server (NTRS)

    Degrijp, Marinus H. K.; Keel, William C.; Miley, George K.

    1987-01-01

    IRAS additional observations were used to obtain a sample of point sources at much fainter flux levels than hitherto available through the IRAS Point Source Catalogue. This sample is being used to compile an incomplete but representative catalogue of faint IRAS candidate Active Galactic Nuclei (AGNs) and to study the evolution of the infrared bright galaxies. Ground based follow up observations (optical spectroscopy) are mainly hampered by identification confusion.

  7. The Swift AGN and Cluster Survey

    NASA Astrophysics Data System (ADS)

    Danae Griffin, Rhiannon; Dai, Xinyu; Kochanek, Christopher S.; Bregman, Joel N.; Nugent, Jenna

    2016-01-01

    The Swift active galactic nucleus (AGN) and Cluster Survey (SACS) uses 125 deg^2 of Swift X-ray Telescope serendipitous fields with variable depths surrounding X-ray bursts to provide a medium depth (4 × 10^-15 erg cm^-2 s^-1) and area survey filling the gap between deep, narrow Chandra/XMM-Newton surveys and wide, shallow ROSAT surveys. Here, we present the first two papers in a series of publications for SACS. In the first paper, we introduce our method and catalog of 22,563 point sources and 442 extended sources. We examine the number counts of the AGN and galaxy cluster populations. SACS provides excellent constraints on the AGN number counts at the bright end with negligible uncertainties due to cosmic variance, and these constraints are consistent with previous measurements. The depth and areal coverage of SACS is well suited for galaxy cluster surveys outside the local universe, reaching z ˜ 1 for massive clusters. In the second paper, we use Sloan Digital Sky Survey (SDSS) DR8 data to study the 203 extended SACS sources that are located within the SDSS footprint. We search for galaxy over-densities in 3-D space using SDSS galaxies and their photometric redshifts near the Swift galaxy cluster candidates. We find 103 Swift clusters with a > 3σ over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmations as galaxy clusters. We present a series of cluster properties including the redshift, BCG magnitude, BCG-to-X-ray center offset, optical richness, X-ray luminosity and red sequences. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z ≤ 0.3 and 80% complete for z ≤ 0.4, consistent with the survey depth of SDSS. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 2 and 1 matches in optical, X-ray and SZ catalogs, respectively, so the majority of these

  8. Gamma-ray-selected AGN

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2016-08-01

    The gamma-ray band is the most energetic part of the electromagnetic spectrum. As such it is also where selection effects are most severe, as it can only be reached by the most extreme non-thermal AGN. Blazars, with their emission dominated by non-thermal blue-shifted radiation arising in a relativistic jet pointed in the direction of the observer, naturally satisfy this though requirement. For this reason, albeit these sources are intrisically very rare (orders of magnitude less abundant than radio quiet AGN of the same optical magnitude) they almost completely dominate the extragalactic gamma-ray and very high energy sky. I will discuss the emission of different types of blazars and the selection effects that are at play in the gamma-ray band based on recent results from the current generation of gamma-ray astronomy satellites, ground-based Cherenkov telescopes, and Monte Carlo simulations.

  9. Dust Obscured AGN are Masquerading as Star Formation in the Early Universe

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric

    2016-01-01

    The buildup of stellar and black hole mass peaked during z=1-3, making this a key epoch for understanding how the interplay of star formation and an active galactic nucleus (AGN) drive galaxy evolution. IR luminous galaxies, which are massive and heavily dust obscured (LIR > 1011 Lsun), dominate the stellar growth during this era, and many are harboring a hidden AGN. I have quantified the contribution of AGN heating to the infrared emission of 343 IR luminous galaxies from z=0.5-2.8 using Spitzer mid-IR spectroscopy, available for every source, making this an unprecedented sample. I classify sources as star forming galaxies, AGN, or composites based on the presence of mid-IR continuum emission due to a dusty torus. My findings are: 1) Surprisingly, 60% of IR luminous galaxies show signs of some dust heating emanating from an AGN. I quantify the far-IR emission using deep Herschel imaging and find that the strength of mid-IR AGN emission is tightly correlated with the total contribution of an AGN to LIR, which has important consequences for calculating star formation rates in dusty high redshift galaxies. I demonstrate techniques to remove the contribution of AGN to LIR when mid-IR spectroscopy is available and when only limited photometry is available. 2) The composites are a separate class of galaxy which show a true mix of star formation and AGN activity in their mid- and far-IR emission. Because of dust obscuration, this activity is largely undetected at other wavelengths. This composite population is important for understanding galaxy evolution and makes up at least 30% of the deepest IR selected samples. I underscore the importance of considering composite galaxies separately in studies of star formation and black hole growth at high redshift.

  10. Comparing Simulations of AGN Feedback

    NASA Astrophysics Data System (ADS)

    Richardson, Mark L. A.; Scannapieco, Evan; Devriendt, Julien; Slyz, Adrianne; Thacker, Robert J.; Dubois, Yohan; Wurster, James; Silk, Joseph

    2016-07-01

    We perform adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) cosmological zoom simulations of a region around a forming galaxy cluster, comparing the ability of the methods to handle successively more complex baryonic physics. In the simplest, non-radiative case, the two methods are in good agreement with each other, but the SPH simulations generate central cores with slightly lower entropies and virial shocks at slightly larger radii, consistent with what has been seen in previous studies. The inclusion of radiative cooling, star formation, and stellar feedback leads to much larger differences between the two methods. Most dramatically, at z=5, rapid cooling in the AMR case moves the accretion shock to well within the virial radius, while this shock remains near the virial radius in the SPH case, due to excess heating, coupled with poorer capturing of the shock width. On the other hand, the addition of feedback from active galactic nuclei (AGNs) to the simulations results in much better agreement between the methods. For our AGN model, both simulations display halo gas entropies of 100 keV cm2, similar decrements in the star formation rate, and a drop in the halo baryon content of roughly 30%. This is consistent with the AGN growth being self-regulated, regardless of the numerical method. However, the simulations with AGN feedback continue to differ in aspects that are not self-regulated, such that in SPH a larger volume of gas is impacted by feedback, and the cluster still has a lower entropy central core.

  11. Feedback from AGN: The Kinetic/Radio Luminosity Function

    NASA Astrophysics Data System (ADS)

    Melini, Gabriele; La Franca, Fabio; Fiore, Fabrizio

    2010-05-01

    We have measured the probability distribution function of the ratio RX = log L1.4/LX, where L1.4/LX = ν Lν(1.4 GHz)/LX(2-10 keV), between the 1.4 GHz and the unabsorbed 2-10 keV luminosities and its dependence on LX and z. We have used a complete sample of ~1800 hard X-ray selected AGN, observed in the 1.4 GHz band, cross-correlated in order to exclude FR II-type objects, and thus obtain a contemporaneous measure of the radio and X-ray emission. The distribution P(RX|LX,z) is shown in Figure 1. Convolution of the distribution P(RX|LX,z) with the 2-10 keV X-ray AGN luminosity function from La Franca et al. (2005) and the relations between radio power and kinetic energy from Best et al. (2006) and Willott et al. (1999) allows us to derive the AGN kinetic power and its evolution. As shown in Figure 1, our results are in good agreement with the predictions of the most recent models of galaxy formation and evolution (e.g., Croton et al. 2006), where AGN radio feedback is required to quench the star formation.

  12. Type 1 AGN at low z- I. Emission properties

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Laor, Ari

    2012-06-01

    We analyse the emission properties of a new sample of 3579 type 1 AGN, selected from Sloan Digital Sky Survey (SDSS) Data Release 7 based on the detection of broad Hα emission. The sample extends over a broad Hα luminosity LbHα of ? and a broad Hα full width at half-maximum (FWHM) of ?, which covers the range of black hole mass 106 < MBH/M⊙ < 109.5 and luminosity in Eddington units 10-3 < L/LEdd < 1. We combine ROSAT, GALEX and 2MASS observations to form the spectral energy distribution (SED) from 2.2 ?m to 2 keV. We find the following. (1) The distribution of the Hα FWHM values is independent of luminosity. (2) The observed mean optical-ultraviolet (optical-UV) SED is well matched by a fixed-shape SED of luminous quasars, which scales linearly with LbHα, and a host galaxy contribution. (3) The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission-line galaxies (NEGs), consistent with a fixed fraction of ˜3 per cent of NEGs hosting an AGN, regardless of the host luminosity. (4) The hosts of lower luminosity AGN have a mean z-band luminosity and u-z colour which are identical to NEGs with the same redshift distribution. With increasing LbHα the AGN hosts become bluer and less luminous than NEGs. The implied increasing star formation rate with LbHα is consistent with the relation for SDSS type 2 AGN of similar bolometric luminosity. (5) The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. (6) There is a rather tight relation between ? and LbHα, which provides a useful probe for unobscured (true) type 2 AGN. (7) The primary parameter that drives the X-ray to UV emission ratio is luminosity, rather than MBH or L/LEdd.

  13. A Sub-Arcsecond Mid-Infrared Survey of X-Ray-Selected AGN

    NASA Astrophysics Data System (ADS)

    Levenson, N. A.; Alonso-Herrero, A.; Packham, Chris; Los Piratas AGN Science Team

    2015-08-01

    Detailed studies of local active galactic nuclei (AGN) following X-ray selection yields significant measurements of the physical properties of the AGN and their host galaxies. In turn, the complete analysis of the nearby cases at high spatial resolution---to distinguish multiple physical components---and high signal-to-noise ratio informs broader surveys of more distant examples where such observations are not possible. We apply these methods in the Los Piratas survey, which emphasizes new observations at mid-infrared wavelengths obtained using CanariCam on the 10.4m Gran Telescopio Canarias. We measure intrinsic bolometric luminosity of the roughly 100 AGN in the sample using X-rays, ensuring a span of luminosity over a range of activity level (from low-ionization nuclei through Seyfert galaxies and quasars), optical type, and radio loudness. The mid-infrared observations at resolution of ~0.3arcsec correspond to typical spatial scales of 60 pc for the low-luminosity AGN and Seyferts and 400 pc for other types. We isolate the AGN emission that is reprocessed by dust in the central regions, which we model in a clumpy distribution. We distinguish this emission from the stellar contributions on larger scales. Across types, the AGN-heated dust emission is overall well-correlated with the X-ray flux, but stellar contributions can be significant on larger scales, especially at moderate AGN luminosity.

  14. Triggering processes and star formation in AGN: multi-wavelength matters

    NASA Astrophysics Data System (ADS)

    Ellison, Sara

    2016-08-01

    AGN can be selected via an array of multi-wavelength diagnostics, spanning the X-ray and optical, to the mid-IR and radio. Many studies of AGN and host galaxy properties focus on samples selected in only one of these domains. However, AGN selected at different wavelengths can exhibit very different properties, such that understanding the "big picture" requires a simultaneous multi-wavelength approach. In this talk, I will present a homogeneous analysis of 3 large samples of z~0 AGN, selected in the radio, mid-IR and optical in order to address the following two questions: what are the triggering mechanisms of AGN accretion, and what are the star formation rates of the host galaxies? Thanks to the combination of multi-wavelength data, large samples, and homogeneous treatment, it is possible to distinguish different triggering mechanisms (e.g. mergers vs. secular) contributing to different AGN samples, and clearly measure differences in their relative star formation rates.

  15. The Study of Relativistic AGN Jets and Experimental Survey of AGN Properties

    NASA Astrophysics Data System (ADS)

    Sabzali, V.; Davoudifar, P.; Mickaelian, A. M.

    2016-09-01

    AGN, their evolution and their relativistic jets were studied on the basis of data from multi-wavelength surveys. NRAO VLA Sky Survey (NVSS) and VLBI were used to study radio jets and radio continuum emission of AGN. A population of AGN will be selected and used in a future optical survey for their jets.

  16. AKARI infrared camera observations of the 3.3 μm PAH feature in Swift/BAT AGNs

    NASA Astrophysics Data System (ADS)

    Castro, Angel; Miyaji, Takamitsu; Shirahata, Mai; Ichikawa, Kohei; Oyabu, Shinki; Clark, David M.; Imanishi, Masatoshi; Nakagawa, Takao; Ueda, Yoshihiro

    2014-12-01

    We explore the relationships between the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature 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 InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is selected from the nine-month Swift/BAT survey in the 14-195 keV band and all of them have measured X-ray spectra at E ≲ 10 keV. These X-ray spectra provide measurements of the neutral hydrogen column density (NH) towards the AGNs. We use the 3.3 μm PAH luminosity (L3.3μm) as a proxy for star-formation activity and hard X-ray luminosity (L14-195 keV) as an indicator of the AGN activity. We search for possible differences in star-formation activity between type 1 (unabsorbed) and type 2 (absorbed) AGNs. We have made several statistical analyses taking the upper limits of the PAH lines into account utilizing survival analysis methods. The results of our log (L14-195 keV) versus log (L3.3 μm) regression show a positive correlation and the slope for the type 1/unobscured AGNs is steeper than that of type 2/obscured AGNs at a 3 σ level. Our analysis also shows that the circumnuclear star formation is more enhanced in type 2/absorbed AGNs than type 1/unabsorbed AGNs for low X-ray luminosity/low Eddington ratio AGNs, while there is no significant dependence of star-formation activities on the AGN type in the high X-ray luminosities/Eddington ratios.

  17. A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

    NASA Astrophysics Data System (ADS)

    Menzel, M.-L.; Merloni, A.; Georgakakis, A.; Salvato, M.; Aubourg, E.; Brandt, W. N.; Brusa, M.; Buchner, J.; Dwelly, T.; Nandra, K.; Pâris, I.; Petitjean, P.; Schwope, A.

    2016-03-01

    This paper presents a survey of X-ray-selected active galactic nuclei (AGNs) with optical spectroscopic follow-up in a ˜ 18 deg2 area of the equatorial XMM-XXL north field. A sample of 8445 point-like X-ray sources detected by XMM-Newton above a limiting flux of F_{0.5-10 keV} > 10^{-15} erg cm^{-2} s^{-1} was matched to optical (Sloan Digital Sky Survey, SDSS) and infrared (IR; WISE) counterparts. We followed up 3042 sources brighter than r = 22.5 mag with the SDSS Baryon Oscillation Spectroscopic Survey (BOSS) spectrograph. The spectra yielded a reliable redshift measurement for 2578 AGNs in the redshift range z = 0.02-5.0, with 0.5-2 keV luminosities ranging from 1039-1046 erg s- 1. This is currently the largest published spectroscopic sample of X-ray-selected AGNs in a contiguous area. The BOSS spectra of AGN candidates show a distribution of optical line widths which is clearly bimodal, allowing an efficient separation between broad- and narrow-emission line AGNs. The former dominate our sample (70 per cent) due to the relatively bright X-ray flux limit and the optical BOSS magnitude limit. We classify the narrow-emission line objects (22 per cent of the full sample) using standard optical emission line diagnostics: the majority have line ratios indicating the dominant source of ionization is the AGN. A small number (8 per cent of the full sample) exhibit the typical narrow line ratios of star-forming galaxies, or only have absorption lines in their spectra. We term the latter two classes `elusive' AGN, which would not be easy to identify correctly without their X-ray emission. We also compare X-ray (XMM-Newton), optical colour (SDSS) and and IR (WISE) AGN selections in this field. X-ray observations reveal, by far, the largest number of AGN. The overlap between the selections, which is a strong function of the imaging depth in a given band, is also remarkably small. We show using spectral stacking that a large fraction of the X-ray AGNs would not be

  18. Probing AGN Unification with galaxy neighbours: pitfalls and prospects

    NASA Astrophysics Data System (ADS)

    Villarroel, B.

    2015-09-01

    Statistical tests of AGN unification harbour many caveats. One way of constraining the validity of the AGN unification is through studies of close neighbours to Type-1 and Type-2 AGN. Examining thousands of AGN- galaxy pairs from the Sloan Digital Sky Survey Data Release 7 and the Galaxy Zoo project, we found that Type-2 AGN appear to reside in more star-forming environments than Type-1 AGN.

  19. AGN Clustering in the Local Universe: An Unbiased Picture from Swift-BAT

    SciTech Connect

    Cappelluti, N.; Ajello, M.; Burlon, D.; Krumpe, M.; Miyaji, T.; Bonoli, S.; Greiner, J.; /Garching, Max Planck Inst., MPE

    2011-08-11

    We present the clustering measurement of hard X-ray selected AGN in the local Universe. We used a sample of 199 sources spectroscopically confirmed detected by Swift-BAT in its 15-55 keV all-sky survey. We measured the real space projected auto-correlation function and detected a signal significant on projected scales lower than 200 Mpc/h. We measured a correlation length of r{sub 0} = 5.56{sup +0.49}{sub -0.43} Mpc/h and a slope {gamma} = 1.64{sup -0.08}{sub -0.07}. We also measured the auto-correlation function of Tyep I and Type II AGN and found higher correlation length for Type I AGN. We have a marginal evidence of luminosity dependent clustering of AGN, as we detected a larger correlation length of luminous AGN than that of low luminosity sources. The corresponding typical host DM halo masses of Swift-BAT are {approx} log(M{sub DMH) {approx} 12-14 h{sup -1}M/M{sub {circle_dot}} which is the typical mass of a galaxy group. We estimated that the local AGN population has a typical lifetime {tau}{sub AGN} {approx}0.7 Gyr, it is powered by SMBH with mass M{sub BH} {approx}1-10x10{sup 8} M{sub {circle_dot}} and accreting with very low efficiency, log({epsilon}){approx}-2.0>. We also conclude that local AGN galaxies are typically red-massive galaxies with stellar mass of the order 2-80x10{sup 10} h{sup -1}M{sub {circle_dot}}. We compared our results with clustering predictions of merger-driven AGN triggering models and found a good agreement.

  20. HOST GALAXIES, CLUSTERING, EDDINGTON RATIOS, AND EVOLUTION OF RADIO, X-RAY, AND INFRARED-SELECTED AGNs

    SciTech Connect

    Hickox, Ryan C.; Jones, Christine; Forman, William R.; Murray, Stephen S.; Brodwin, Mark; Narayan, Ramesh; Kenter, Almus; Caldwell, Nelson; Anderson, Michael E.; Kochanek, Christopher S.; Eisenstein, Daniel; Jannuzi, Buell T.; Dey, Arjun; Brown, Michael J. I.; Stern, Daniel; Eisenhardt, Peter R.; Gorjian, Varoujan; Cool, Richard J.

    2009-05-01

    We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared (IR) wavebands. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES). We select AGNs with observations in the radio at 1.4 GHz from the Westerbork Synthesis Radio Telescope, X-rays from the Chandra XBooetes Survey, and mid-IR from the Spitzer IRAC Shallow Survey. The radio, X-ray, and IR AGN samples show only modest overlap, indicating that to the flux limits of the survey, they represent largely distinct classes of AGNs. We derive host galaxy colors and luminosities, as well as Eddington ratios, for obscured or optically faint AGNs. We also measure the two-point cross-correlation between AGNs and galaxies on scales of 0.3-10 h {sup -1} Mpc, and derive typical dark matter halo masses. We find that: (1) radio AGNs are mainly found in luminous red sequence galaxies, are strongly clustered (with M {sub halo} {approx} 3 x 10{sup 13} h {sup -1} M {sub sun}), and have very low Eddington ratios {lambda} {approx}< 10{sup -3}; (2) X-ray-selected AGNs are preferentially found in galaxies that lie in the 'green valley' of color-magnitude space and are clustered similar to the typical AGES galaxies (M {sub halo} {approx} 10{sup 13} h {sup -1} M {sub sun}), with 10{sup -3} {approx}< {lambda} {approx}< 1; (3) IR AGNs reside in slightly bluer, slightly less luminous galaxies than X-ray AGNs, are weakly clustered (M {sub halo} {approx}< 10{sup 12} h {sup -1} M {sub sun}), and have {lambda}>10{sup -2}. We interpret these results in terms of a simple model of AGN and galaxy evolution, whereby a 'quasar' phase and the growth of the stellar bulge occurs when a galaxy's dark matter halo reaches a critical mass between {approx}10{sup 12} and 10{sup 13} M {sub sun}. After this event

  1. Star formation and obscuration in AGN: A sub-mm study of high-redshift mid-IR selected type-2 QSOs

    NASA Astrophysics Data System (ADS)

    Violino, Giulio; Stevens, Jason; Coppin, Kristen; Geach, James

    2016-08-01

    The AGN unification model describes unobscured and obscured AGN (AGN1 and AGN2) as identical sources, with their different observed properties explained solely by orientation effects; as a result, it predicts no difference in the host galaxies. As an alternative, a second scenario has been proposed in which type-2 AGN represent an earlier stage in the life of AGN characterized by dust-enshrouded host galaxies which contribute to the obscuration and higher star formation activity, at least at earlier epochs. To test this scenario we employ Herschel data at three different wavelengths (250, 350, 500 um) to study the far-IR-to-submm properties of a sample of mid-IR selected type 2 QSOs at high redshift (1.5sample of type-1 QSOs selected in the same field. Through SED fitting we are able to disentangle AGN and star-formation activity and consequently derive FIR luminosities of the two components, as well as SFRs and dust masses. We propose a picture in which intermediate-level radio activity in the core (pc scale) of AGN is linked to the obscuration of the nucleus (perhaps via a merger) since our AGN1 have systematically lower radio luminosities than our AGN2.

  2. The Search for Molecular Outflows in Local Volume AGNs with Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Stone, M.; Veilleux, S.; Meléndez, M.; Sturm, E.; Graciá-Carpio, J.; González-Alfonso, E.

    2016-08-01

    We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d\\lt 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGNs) with Herschel-PACS. We combine the results from our analysis of the BAT AGNs with the published Herschel/PACS data of 43 nearby (z\\lt 0.3) galaxy mergers, mostly ultra-luminous infrared galaxies (ULIRGs) and QSOs. The objects in our sample of BAT AGNs have, on average, ˜ 10{--}100 times lower AGN luminosities, star formation rates, and stellar masses than those of the ULIRG and QSO samples. OH 119 μm is detected in 42 of our BAT AGN targets. Evidence for molecular outflows (i.e., OH absorption profiles with median velocities more blueshifted than -50 km s-1 and/or blueshifted wings with 84% velocities less than -300 km s-1) is seen in only four BAT AGNs (NGC 7479 is the most convincing case). Evidence for molecular inflows (i.e., OH absorption profiles with median velocities more redshifted than 50 km s-1) is seen in seven objects, although an inverted P-Cygni profile is detected unambiguously in only one object (Circinus). Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGNs with quasar-like luminosities. We also confirm that the total absorption strength of OH 119 μm is a good proxy for dust optical depth as it correlates strongly with the 9.7 μm silicate absorption feature, a measure of obscuration originating in both the nuclear torus and host galaxy disk. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  3. The Search for Molecular Outflows in Local Volume AGNs with Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Stone, M.; Veilleux, S.; Meléndez, M.; Sturm, E.; Graciá-Carpio, J.; González-Alfonso, E.

    2016-08-01

    We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d\\lt 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGNs) with Herschel-PACS. We combine the results from our analysis of the BAT AGNs with the published Herschel/PACS data of 43 nearby (z\\lt 0.3) galaxy mergers, mostly ultra-luminous infrared galaxies (ULIRGs) and QSOs. The objects in our sample of BAT AGNs have, on average, ˜ 10{--}100 times lower AGN luminosities, star formation rates, and stellar masses than those of the ULIRG and QSO samples. OH 119 μm is detected in 42 of our BAT AGN targets. Evidence for molecular outflows (i.e., OH absorption profiles with median velocities more blueshifted than ‑50 km s‑1 and/or blueshifted wings with 84% velocities less than ‑300 km s‑1) is seen in only four BAT AGNs (NGC 7479 is the most convincing case). Evidence for molecular inflows (i.e., OH absorption profiles with median velocities more redshifted than 50 km s‑1) is seen in seven objects, although an inverted P-Cygni profile is detected unambiguously in only one object (Circinus). Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGNs with quasar-like luminosities. We also confirm that the total absorption strength of OH 119 μm is a good proxy for dust optical depth as it correlates strongly with the 9.7 μm silicate absorption feature, a measure of obscuration originating in both the nuclear torus and host galaxy disk. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  4. Highly variable AGN from the XMM-Newton slew survey

    NASA Astrophysics Data System (ADS)

    Strotjohann, N. L.; Saxton, R. D.; Starling, R. L. C.; Esquej, P.; Read, A. M.; Evans, P. A.; Miniutti, G.

    2016-07-01

    Aims: We investigate the properties of a variability-selected complete sample of active galactic nuclei (AGN) in order to identify the mechanisms which cause large amplitude X-ray variability on timescales of years. Methods: A complete sample of 24 sources was constructed, from AGN which changed their soft X-ray luminosity by more than one order of magnitude over 5-20 years between ROSAT observations and the XMM-Newton slew survey. Follow-up observations were obtained with the Swift satellite. We analysed the spectra of these AGN at the Swift and XMM observation epochs, where six sources had continued to display extreme variability. Multiwavelength data are used to calculate black hole masses and the relative X-ray brightness αOX. Results: After removal of two probable spurious sources, we find that the sample has global properties which differ little from a non-varying control sample drawn from the wider XMM-slew/ROSAT/Veron sample of all secure AGN detections. A wide range of AGN types are represented in the varying sample. The black hole mass distributions for the varying and non-varying sample are not significantly different. This suggests that long timescale variability is not strongly affected by black hole mass. There is marginal evidence that the variable sources have a lower redshift (2σ) and X-ray luminosity (1.7σ). Apart from two radio-loud sources, the sample sources have normal optical-X-ray ratios (αOX) when at their peak but are X-ray weak during their lowest flux measurements. Conclusions: Drawing on our results and other studies, we are able to identify a variety of variability mechanisms at play: tidal disruption events, jet activity, changes in absorption, thermal emission from the inner accretion disc, and variable accretion disc reflection. Little evidence for strong absorption is seen in the majority of the sample and single-component absorption can be excluded as the mechanism for most sources.

  5. Prospects for AGN Science using the ART-XC on the SRG Mission

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Elsner, Ronald F.; Gubarev, Mikhail V.; O'Dell, Stephen L.; Ramsey, Brian D.; Bonamente, Massimiliano

    2012-01-01

    The enhanced hard X-ray sensitivity provided by the Astronomical Roentgen Telescope to the Spectrum Roentgen Gamma mission facilitates the detection of heavily obscured and other hard-spectrum cosmic X-ray sources. The SRG all-sky survey will obtain large, statistically-well-defined samples of active galactic nuclei (AGN) including a significant population of local heavily-obscured AGN. In anticipation of the SRG all-sky survey, we investigate the prospects for refining the bright end of the AGN luminosity function and determination of the local black hole mass function and comparing the spatial distribution of AGN with large-scale structure defined by galaxy clusters and groups. Particular emphasis is placed on studies of the deep survey Ecliptic Pole regions.

  6. SWIFT BAT Survey of AGN

    NASA Technical Reports Server (NTRS)

    Tueller, J.; Mushotzky, R. F.; Barthelmy, S.; Cannizzo, J. K.; Gehrels, N.; Markwardt, C. B.; Skinner, G. K.; Winter, L. M.

    2008-01-01

    We present the results1 of the analysis of the first 9 months of data of the Swift BAT survey of AGN in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGN) of 130 objects detected at [b] > 15deg and with significance > 4.8-delta. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the logN - log S distribution, and find the slope to be 1.42+/-0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity logL*(ergs/s)= 43.85+/-0.26. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGN above 10(exp 41) erg/s of 2.4x10(exp -3) Mpc(sup -3), which is about 10% of the total luminous local galaxy density above M* = -19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log nH is essentially flat from nH = 10(exp 20)/sq cm to 10(exp 24)/sq cm, with 50% of the objects having column densities of less than 10(exp 22)/sq cm. BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log nH > 22.

  7. Disentangling Dominance: Obscured AGN Activity versus Star Formation in BPT-Composites

    NASA Astrophysics Data System (ADS)

    Trouille, Laura

    2011-11-01

    Approximately 20% of SDSS emission-line galaxies (ELG) lie in the BPT-comp regime, between the Kauffmann et al. (2003) empirically determined SF-dominated regime and the Kewley et al. (2001) theoretically predicted AGN-dominated regime. BPT-AGN, on the other hand, make up only 11% of the ELG population. Whether to include the significant number of BPT-comp in samples of AGN or samples of star-forming galaxies is an open question and has important implications for galaxy evolution studies, metallicity studies, etc. Using a large pectroscopic sample of GOODS-N and LH galaxies with deep Chandra imaging, we perform an X-ray stacking analysis of BPT-comp. We find the stacked signal to be X-ray hard. This X-ray hardness can be indicative of obscured AGN activity or the presence of HMXBs associated with ongoing star formation. In order to distinguish between these scenarios, we perform an IR stacking analysis using Spitzer 24 micron data. The stacked BPT-comp lies well above the expected value for L_x/L_IR for pure star-forming galaxies; similarly for the X-ray detected BPT-comp. We also find that the BPT-comp lie in the AGN-dominated regime of our new TBT diagnostic, which uses [NeIII]/[OII] versus rest-frame g-z colour to identify AGN and star forming galaxies out to z=1.4. [NeIII], which has a higher ionisation potential than other commonly used forbidden emission lines, appears to foster a more reliable selection of AGN-dominated galaxies. These findings suggest that both the X-ray and optical signal in BPT-comp are dominated by obscured or low accretion rate AGN activity rather than star formation. This is in contrast to claims by previous optical emission-line studies that the signal in BPT-comp is dominated by star-formation activity. Therefore, we recommend that groups carefully consider the impact of excluding or including BPT-comp on the interpretation of their results. For example, for studies involving determining the bolometric contribution from AGN activity

  8. AGN Winds and Blazar Phenomenology

    NASA Technical Reports Server (NTRS)

    Kazanas, Demos

    2012-01-01

    The launch of {\\em Fermi} produced a significant number of AGN detections to allow statistical treatment of their properties. One of the first such systematics was the "Blazar Divide" in FSRQs and BL Lacs according to their gamma-ray spectral index and luminosity. Further data accumulation indicated this separation to be less clear than thought before. An MHD wind model which can model successfully the Seyfert X-ray absorber properties provides the vestiges of an account of the observed blazar classification. We propose to employ this model to model in detail the broad band blazar spectra and their statistical properties in terms of the physical parameters of these MHD winds.

  9. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    SciTech Connect

    Zhu, Yi-Nan; Wu, Hong E-mail: hwu@bao.ac.cn

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  10. AGN Zoo and Classifications of Active Galaxies

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.

    2015-07-01

    We review the variety of Active Galactic Nuclei (AGN) classes (so-called "AGN zoo") and classification schemes of galaxies by activity types based on their optical emission-line spectrum, as well as other parameters and other than optical wavelength ranges. A historical overview of discoveries of various types of active galaxies is given, including Seyfert galaxies, radio galaxies, QSOs, BL Lacertae objects, Starbursts, LINERs, etc. Various kinds of AGN diagnostics are discussed. All known AGN types and subtypes are presented and described to have a homogeneous classification scheme based on the optical emission-line spectra and in many cases, also other parameters. Problems connected with accurate classifications and open questions related to AGN and their classes are discussed and summarized.

  11. Pharmacokinetics of a novel retinoid AGN 190168 and its metabolite AGN 190299 after intravenous administration of AGN 190168 to rats.

    PubMed

    Hsyu, P H; Bowen, B; Tang-Liu, D

    1994-07-01

    The pharmacokinetics of AGN 190168, a novel synthetic retinoid, and its major metabolite, AGN 190299, in rat blood after intravenous administration was investigated. Approximately 4.4 mg kg-1 (high dose) or 0.49 mg kg-1 (low dose) of AGN 190168 was administered to rats via the femoral vein. Blood was collected from the femoral artery at various time points during an 8 h period. Blood concentrations of AGN 190168 and AGN 190299 were determined by a specific and sensitive high-pressure liquid chromatographic (HPLC) method. AGN 190168 was rapidly metabolized in rats. The only detectable drug-related species in the blood was AGN 190299. Therefore, only pharmacokinetics of AGN 190299 were calculated. Elimination of AGN 190299 appeared to be non-linear after administration of the high dose, and linear after administration of the low dose. The maximum elimination rate (Vmax) and the concentration at half of the Vmax (km), as estimated by a Michaelis-Menten one-compartment model, were 7.58 +/- 2.42 micrograms min-1 (mean +/- SD) and 6.10 +/- 1.58 micrograms mL-1, respectively. The value of the area under the blood concentration time curve (AUC) was 9.54 +/- 1.68 micrograms h mL-1 after administration of the high dose and 0.594 +/- 0.095 micrograms h mL-1 after administration of the low dose. The clearance value was 7.79 +/- 1.20 mL min-1 kg-1 after the high dose, statistically significantly different from that after the low dose (p < 0.05), 14.0 +/- 2.2 mL min-1 kg-1. The terminal half-life (t1/2) was 1.25 +/- 0.74 h for the high-dose group and 0.95 +/- 0.16 h for the low-dose group. Study results demonstrate rapid systemic metabolism of AGN 190168 to AGN 190299, non-linear pharmacokinetics of AGN 190299 after the 4.4 mg kg-1 dose, and the lack of difference in disposition profiles between sexes after intravenous administration of AGN 190168 to rats.

  12. A 2.5-5 μm spectroscopic study of hard X-ray selected AGNs with AKARI

    NASA Astrophysics Data System (ADS)

    Castro, A.; Miyaji, T.; Shirahata, M.; Oyabu, S.; Clark, D.; Ichikawa, K.; Imanishi, M.; Nakagawa, T.; Ueda, Y.

    2014-07-01

    We explore the relationships between the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature 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 InfraRed Camera (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. These X-ray spectra provide measurements of the neutral hydrogen column density (N H) towards the AGNs. We use the 3.3 μm PAH luminosity (L 3.3μm) as a proxy for star formation activity and hard X-ray luminosity (L 14-195keV) as an indicator of the AGN activity. We searched for possible difference of star-formation activity between type 1 (un-absorbed) and type 2 (absorbed) AGNs. Our regression analysis of log L 14-195keV versus log L 3.3μm shows a positive correlation and the slope seems steeper for type 1/unobscured AGNs than that of type 2/obscured AGNs. The same trend has been found for the log (L 14-195keV/M BH) versus log (L 3.3μm/MBH) correlation. Our analysis show that the circum-nuclear star-formation is more enhanced in type 2/absorbed AGNs than type 1/un-absorbed AGNs for low X-ray luminosity/low Eddington ratio AGNs.

  13. Searching for Dual AGNs in Galaxy Mergers: Understanding Double-Peaked [O III] and Ultra Hard X-rays as Selection Method

    NASA Astrophysics Data System (ADS)

    McGurk, Rosalie C.; Max, Claire E.; Medling, Anne; Shields, Gregory A.

    2015-01-01

    When galaxies merge, gas accretes onto both central supermassive black holes. Thus, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O III] or of ultra hard X-rays have been proposed as techniques to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O III] emitting AGNs from SDSS DR7. By obtaining new and archival high spatial resolution images taken with the Keck 2 Laser Guide Star Adaptive Optics system and the near-infrared (IR) camera NIRC2, we showed that 30% of double-peaked [O III] emission line SDSS AGNs have two spatial components within a 3' radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up these spatially-double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and Gemini GMOS and with long-slit spectroscopy from Keck NIRSPEC and Shane Kast Double Spectrograph. We find double-peaked emitters are caused sometimes by dual AGN and sometimes by outflows or narrow line kinematics. We also performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs. Using our observations and 8 archival observations, we compare the distribution of X-ray photons to our spatially double near-IR images, measure X-ray luminosities and hardness ratios, and estimate column densities. By assessing what fraction of double-peaked emission line SDSS AGNs are true dual AGNs, we can better determine whether double-peaked [O III] is an efficient dual AGN indicator and constrain the statistics of dual AGNs. A second technique to find dual AGN is the detection of ultra hard X-rays by the Swift Burst Alert Telescope. We use CARMA observations to measure and map the CO(1-0) present in nearby ultra-hard X-ray Active Galactic Nuclei (AGNs) merging with either a quiescent companion

  14. X-Ray Cavities in a Sample of 83 SPT-selected Clusters of Galaxies: Tracing the Evolution of AGN Feedback in Clusters of Galaxies out to z=1.2

    NASA Astrophysics Data System (ADS)

    Hlavacek-Larrondo, J.; McDonald, M.; Benson, B. A.; Forman, W. R.; Allen, S. W.; Bleem, L. E.; Ashby, M. L. N.; Bocquet, S.; Brodwin, M.; Dietrich, J. P.; Jones, C.; Liu, J.; Reichardt, C. L.; Saliwanchik, B. R.; Saro, A.; Schrabback, T.; Song, J.; Stalder, B.; Vikhlinin, A.; Zenteno, A.

    2015-05-01

    X-ray cavities are key tracers of mechanical (or radio mode) heating arising from the active galactic nuclei (AGNs) in brightest cluster galaxies (BCGs). We report on a survey for X-ray cavities in 83 massive, high-redshift (0.4\\lt z\\lt 1.2) clusters of galaxies selected by their Sunyaev-Zel’dovich signature in the South Pole Telescope data. Based on Chandra X-ray images, we find a total of six clusters having symmetric pairs of surface brightness depressions consistent with the picture of radio jets inflating X-ray cavities in the intracluster medium (ICM). The majority of these detections are of relatively low significance and require deeper follow-up data in order to be confirmed. Further, this search will miss small (<10 kpc) X-ray cavities that are unresolved by Chandra at high (z≳ 0.5) redshift. Despite these limitations, our results suggest that the power generated by AGN feedback in BCGs has remained unchanged for over half of the age of the universe (\\gt 7 Gyr at z˜ 0.8). On average, the detected X-ray cavities have powers of (0.8-5)× {{10}45} erg {{s}-1}, enthalpies of (3-6)× {{10}59} erg, and radii of ˜17 kpc. Integrating over 7 Gyr, we find that the supermassive black holes in BCGs may have accreted 108 to several {{10}9} {{M}⊙ } of material to power these outflows. This level of accretion indicates that significant supermassive black hole growth may occur not only at early times, in the quasar era, but at late times as well. We also find that X-ray cavities at high redshift may inject an excess heat of 0.1-1.0 keV per particle into the hot ICM above and beyond the energy needed to offset cooling. Although this result needs to be confirmed, we note that the magnitude of excess heating is similar to the energy needed to preheat clusters, break self-similarity, and explain the excess entropy in hot atmospheres.

  15. Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

    NASA Astrophysics Data System (ADS)

    Gürkan, G.; Hardcastle, M. J.; Jarvis, M. J.; Smith, D. J. B.; Bourne, N.; Dunne, L.; Maddox, S.; Ivison, R. J.; Fritz, J.

    2015-10-01

    We examine the relationship between star formation and active galactic nuclei (AGN) activity by constructing matched samples of local (0 < z < 0.6) radio-loud and radio-quiet AGN in the Herschel-Astrophysical Terahertz Large Area Survey fields. Radio-loud AGN are classified as high-excitation and low-excitation radio galaxies using their emission lines and WISE 22-μm luminosity. AGN accretion and jet powers in these active galaxies are traced by [O III] emission-line and radio luminosity, respectively. Star formation rates (SFRs) and specific star formation rates (SSFRs) were derived using Herschel 250-μm luminosity and stellar mass measurements from the Sloan Digital Sky Survey-Max Planck Institute for Astrophysics-John Hopkins University catalogue. In the past, star formation studies of AGN have mostly focused on high-redshift sources to observe the thermal dust emission that peaks in the far-infrared, which limited the samples to powerful objects. However, with Herschel we can expand this to low redshifts. Our stacking analyses show that SFRs and SSFRs of both radio-loud and radio-quiet AGN increase with increasing AGN power but that radio-loud AGN tend to have lower SFR. Additionally, radio-quiet AGN are found to have approximately an order of magnitude higher SSFRs than radio-loud AGN for a given level of AGN power. The difference between the star formation properties of radio-loud and -quiet AGN is also seen in samples matched in stellar mass.

  16. ALMA and SINFONI high redshift observations to test AGN feedback

    NASA Astrophysics Data System (ADS)

    Kakkad, D.; Mainieri, V.; Padovani, P.; Cresci, G.; Husemann, B.; Carniani, S.; Brusa, M.; Lamastra, A.; Lanzuisi, G.; Feruglio, C.; Piconcelli, E.; Schramm, M.

    2016-08-01

    The epoch between redshift of 1-3 has become the prime focus of many galaxy evolutionary studies as the accretion rates of super massive black holes at the galactic center and the star formation rates of their hosts peaked around this period, pointing to their co-evolution throughout cosmic history. We will present two different approaches to study the impact of high redshift AGN (z~1.5) on the host galaxy: a) CO(2-1) observations from ALMA in a sample of "main sequence" AGNs to compare the star formation efficiency and gas fractions in active and inactive galaxies. b) SINFONI-IFU observations of a representative sample of high redshift quasars for which we observe intermediate to high velocity outflows using [OIII]5007 line diagnostics. These outflows are extended up-to kiloparsec scales and have an asymmetric geometry. With these approaches, one is able to test the effect of AGN feedback on the molecular as well as the ionized gas content.

  17. Cosmological evolution of compact AGN at 15 GHz

    NASA Astrophysics Data System (ADS)

    Arshakian, T. G.; Ros, E.; Zensus, J. A.

    2006-11-01

    Aims. We study the uniformity of the distribution of compact flat-spectrum active galactic nuclei (AGN) on the sky and the evolution of their relativistic jets with cosmic epoch. Methods: .A complete sample of compact extragalactic radio sources at 2 cm (15 GHz) was recently compiled to conduct the MOJAVE (Monitoring Of Jets in AGN with VLBA Experiments) program (Lister & Homan 2005, AJ, 130, 1389). The MOJAVE sample comprises 133 radio-loud flat-spectrum AGN with compact relativistic outflows detected at parsec scales. We use a two-point angular correlation function to test the isotropy of the distribution of radio sources on the sky. The generalized and banded versions of V/V_max statistic are used to investigate the cosmological evolution of compact AGN. Results: .The survey sources are distributed uniformly on the sky. The source counts of compact AGN shows that the MOJAVE sample represents a flux-limited complete sample. Analysis of the population of flat-spectrum quasars of the sample reveals that the pc-scale jets of quasars have intrinsic luminosities in the range between 1024 W Hz-1 and 1027 {W Hz-1} and Lorentz factors distributed between 3⪉γ ⪉30. We find that the apparent speed (or Lorentz factor) of jets evolves with redshift, increasing from z˜0 to z˜1 and then falling at higher redshifts (z˜2.5) by a factor of 2.5. The evolution of apparent speeds does not affect significantly the evolution of the beamed luminosity function of quasars, which is most likely to be dependent on the evolution of radio luminosity. Furthermore, the beamed radio luminosity function suggests that the intrinsic luminosity function of quasars has a double power-law form: it is flat at low luminosities and steep at high luminosities. There is a positive evolution of quasars at low redshifts (z<0.5) and strong negative evolution at redshifts >1.7 with space density decline up to z˜2.5. This implies that the powerful jets were more populous at redshifts between 0.5 and 1

  18. Cadenced IRAC Monitoring of Infrared-Variable AGNs, Part II

    NASA Astrophysics Data System (ADS)

    Ashby, Matthew; Fouesneau, Morgan; Hora, Joseph; Krick, Jessica; Smith, Howard; Surace, Jason

    2008-03-01

    We have analyzed IRAC imaging data from all 97 Spitzer visits to a very well-studied field, the IRAC Dark Calibration Field (IRAC-CF) near the north ecliptic pole. With this extensive dataset we have already identified a unique sample of 30 IR-variable galaxies which we are now working to characterize with respect to variability amplitudes and timescales, panchromatic SEDs, and host morphologies, among other quantities. Unfortunately, the continual change in spacecraft roll angle means that our sources are typically observed for at most six months at a time by each IRAC FOV in succession -- in other words, the visibility windows are exactly out of phase. Thus the existing data, despite the fact that they extend over more than four years, present large, unavoidable gaps that frustrate the time-delay analysis we wish to perform on exactly the timescales known to be common in active galaxies. This has only changed beginning in 2007 July: since that time cadenced IRAC observations have been carried out in synchrony with the IRAC-CF dark-calibration observations as part of our approved Cycle-4 program (PID 40553). Here we are proposing to continue this successful AGN monitoring campaign until the end of the cryogenic mission. The resulting timelines (covering 1500 days thus far and expected to run ultimately to some 2200+ days), will be a unique legacy of the Spitzer mission. This dataset, especially for the sizable, unbiased AGN sample we now have, holds unique promise for measuring the colors and temperatures of IR-varying AGN, and will have much to say about the underlying physical models of the infrared AGN emission. Accordingly we ask for just 8 h to gather IRAC photometry in the temporal gaps that would otherwise accrue in Cycle 5.

  19. Type 1 AGN at low z. I. Emission properties

    NASA Astrophysics Data System (ADS)

    Stern, J.; Laor, A.

    2012-07-01

    We analyze the emission properties of a new sample of 3 596 type 1 AGN, selected from the SDSS DR7 based on the detection of broad Hα emission. The sample extends over a broad Hα luminosity LbHα of 1040-1044 erg s-1 and a broad Hα FWHM of 1 000-25 000 km s-1, which covers the range of black hole mass 106 < MBH/Modot < 109.5 and luminosity in Eddington units 10-3 < L/LEdd < 1. We combine ROSAT, GALEX and 2MASS observations to form the SED from 2.2 μm to 2 keV. We find the following: 1. The distribution of the Hα FWHM values is independent of luminosity. 2. The observed mean optical-UV SED is well matched by a fixed shape SED of luminous quasars, which scales linearly with LbHα, and a host galaxy contribution. 3. The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission line galaxies (NEG), consistent with a fixed fraction of ~ 3% of NEG hosting an AGN, regardless of the host luminosity. 4. The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. 5. There is a rather tight relation of νLν(2 keV) and LbHα, which provides a useful probe for unobscured (true) type 2 AGN.

  20. AGN and QSOs in the eROSITA All-Sky Survey. II. The large-scale structure

    NASA Astrophysics Data System (ADS)

    Kolodzig, Alexander; Gilfanov, Marat; Hütsi, Gert; Sunyaev, Rashid

    2013-10-01

    The four-year X-ray all-sky survey (eRASS) of the eROSITA telescope aboard the Spektrum-Roentgen-Gamma satellite will detect about 3 million active galactic nuclei (AGN) with a median redshift of z ≈ 1 and a typical luminosity of L0.5-2.0 keV ~ 1044 ergs-1. We show that this unprecedented AGN sample, complemented with redshift information, will supply us with outstanding opportunities for large-scale structure research. For the first time, detailed redshift- and luminosity-resolved studies of the bias factor for X-ray selected AGN will become possible. The eRASS AGN sample will not only improve the redshift- and luminosity resolution of these studies, but will also expand their luminosity range beyond L0.5-2.0 keV ~ 1044 ergs-1, thus enabling a direct comparison of the clustering properties of luminous X-ray AGN and optical quasars. These studies will dramatically improve our understanding of the AGN environment, triggering mechanisms, the growth of supermassive black holes and their co-evolution with dark matter halos. The eRASS AGN sample will become a powerful cosmological probe. It will enable detecting baryonic acoustic oscillations (BAOs) for the first time with X-ray selected AGN. With the data from the entire extragalactic sky, BAO will be detected at a ≳10σ confidence level in the full redshift range and with ~8σ confidence in the 0.8 < z < 2.0 range, which is currently not covered by any existing BAO surveys. To exploit the full potential of the eRASS AGN sample, photometric and spectroscopic surveys of large areas and a sufficient depth will be needed.

  1. AGN Feedback in Overdense Environments at z=2.23

    NASA Astrophysics Data System (ADS)

    Lucy, Adrian B.; Lehmer, B.; Alexander, D. M.; Best, P.; Geach, J.; Harrison, C. M.; Hornschemeier, A. E.; Matsuda, Y.; Mullaney, J.; Smail, I.; Sobral, D.

    2013-01-01

    We present results from a ≈100 ks Chandra observation of the 2QZ Cluster 1004+00 galaxy overdensity at z=2.23. This 2QZ Clus structure was first identified as an overdensity of four optically-selected quasars; that sample was subsequently found to overlap with an overdensity of 22 Hα-emitting galaxies (HAEs) identified through narrow and broad band near-infrared imaging by Matsuda et al. (2011). In addition to the preselected quasars in 2QZ Clus, our Chandra observation reveals that a further three HAEs are X-ray sources, all characterized by X-ray luminosities and spectral slopes consistent with unobscured active galactic nuclei (AGN). In total, we find that ≈30% of HAEs in our observed region of 2QZ Clus are AGN. This AGN fraction is high compared to AGN fractions among HAEs in the Chandra-COSMOS field (C-COSMOS), and if this enhancement is purely a result of the quasar selection bias of our sample, we estimate that such activity is rare at this redshift. Hα is a tracer of star formation, so 2QZ Clus is well suited to the investigation of the coeval growth of supermassive black holes and their host galaxies in the precursors to rich local clusters. Moreover, we have an ideal control sample in C-COSMOS; this survey contains a large sample of HAEs classified identically using infrared imaging, but without any selection of quasars. We calculate AGN fraction as a function of galaxy overdensity in C-COSMOS, and perform stacking analyses of Chandra and 250μ Herschel SPIRE data to obtain mean black hole accretion rates dMBH/dt and star formation rates SFR. Preliminary results indicate that dMBH/dt and its ratio to SFR are significantly elevated in 2QZ Clus compared to similarly overdense regions of C-COSMOS. We discuss these relations in the context of theoretical models describing the emergence of the MBH/Mgal relation of the local Universe.

  2. The Role of Star Formation and an AGN in Dust Heating of z = 0.3-2.8 Galaxies. I. Evolution with Redshift and Luminosity

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric; Yan, Lin; Armus, Lee; Díaz-Santos, Tanio; Stierwalt, Sabrina

    2015-11-01

    We characterize infrared spectral energy distributions of 343 (ultra)luminous infrared galaxies from z = 0.3-2.8. We diagnose the presence of an active galactic nucleus (AGN) by decomposing individual Spitzer mid-IR spectroscopy into emission from star formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGNs, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright S24, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2-1000 μm). We fit the far-IR emission using a two-temperature modified blackbody to measure cold and warm dust temperatures (Tc and Tw). We find that Tc does not depend on mid-IR classification, while Tw shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to LIR. AGNs, composites, and SFGs separate in S8/S3.6 and S250/S24, providing a useful diagnostic for estimating relative amounts of these sources. We estimate that >40% of IR-selected samples host an AGN, even at faint selection thresholds (S24 > 100 μJy). Our decomposition technique and color diagnostics are relevant given upcoming observations with the James Webb Space Telescope.

  3. Characterization of the AGN variability in the optical and Near Infrared regimes

    NASA Astrophysics Data System (ADS)

    Sanchez, Paula; Lira, Paulina; Cartier, Regis

    2016-08-01

    Variability is one of the most defining characteristic of Active Galactic Nuclei (AGN), and it is observed in every waveband in which they have been studied. For this reason variability studies are fundamental to understand the extreme physical conditions of accretion disks near supermassive black holes. Several efforts have been done to analyze the variability in the optical range, however, in order to relate the variability and physical properties of AGN, we need well sampled light curves. On the other hand, very little is known about the variability in the infrared range. This waveband gives us information about the dust surrounding the accretion disk at low redshift, and about the accretion disk at high redshift. In this talk, we will present the current status of our QUEST-La Silla AGN variability survey. This is an effort to obtain well sampled optical light curves of AGN in extragalactic fields with unique multiwavelength observations, using the QUEST camera on the ESO-Schmidt telescope.The survey uses a broadband filter, the Q-band, similar to the union of the g and the r filters. In particular, we will present the status of the analysis of the COSMOS, ELAIS-S1 and Stripe82 fields. Besides, we will present our statistical study of the near infrared (NIR) variability of AGN in the COSMOS field, using UltraVISTA data. This dataset give us a huge sample of light curves, making possible to have a global description of the nature of AGNs for different ranges of redshift, and for different levels of obscuration. By using both surveys, we expect to have a better understanding of the difference between type 1 and type 2 AGN.

  4. The Relation between Luminous AGNs and Star Formation in Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Rieke, G. H.; Egami, E.; Haines, C. P.; Pereira, M. J.; Smith, G. P.

    2015-08-01

    We study the relation of active galactic nuclei (AGNs) to star formation in their host galaxies. Our sample includes 205 Type-1 and 85 Type-2 AGNs, 162 detected with Herschel, from fields surrounding 30 galaxy clusters in the Local Cluster Substructure Survey. The sample is identified by optical line widths and ratios after selection to be brighter than 1 mJy at 24 μm. We show that Type-2 AGN [O iii]λ5007 line fluxes at high z can be contaminated by their host galaxies with typical spectrograph entrance apertures (but our sample is not compromised in this way). We use spectral energy distribution (SED) templates to decompose the galaxy SEDs and estimate star formation rates (SFRs), AGN luminosities, and host galaxy stellar masses (described in an accompanying paper). The AGNs arise from massive black holes (˜ 3× {10}8{M}⊙ ) accreting at ˜10% of the Eddington rate and residing in galaxies with stellar mass \\gt 3× {10}10{M}⊙ ; those detected with Herschel have IR luminosity from star formation in the range of {L}{SF,{IR}}˜ {10}10-{10}12{L}⊙ . We find that (1) the specific SFRs in the host galaxies are generally consistent with those of normal star-forming (main sequence) galaxies; (2) there is a strong correlation between the luminosities from star formation and the AGN; and (3) the correlation may not result from a causal connection, but could arise because the black hole mass (and hence AGN Eddington luminosity) and star formation are both correlated with the galaxy mass.

  5. Toward a Unified AGN Structure

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes; Fukumura, Keigo; Shrader, Chris; Behar, Ehud; Contopoulosa, Ioannis

    2012-01-01

    We present a unified model for the structure and appearance of accretion powered sources across their entire luminosity range from galactic X-ray binaries (XRB) to luminous quasars, with emphasis on AG N and their phenomenology. Central to this model is the notion of MHD winds launched by the accretion disks that power these objects. These winds provide the matter that manifests as blueshifted absorption features in the UV and X-ray spectra of a large fraction of these sources; furthermore, their density distribution in the poloidal plane determines their "appearance" (i.e. the column and velocity structure of these absorption features and the obscuration of the continuum source) as a function of the observer inclination angle (a feature to which INTEGRAL has made significant contributions). This work focuses on just the broadest characteristics of these objects; nonetheless, it provides scaling laws that allow one to reproduce within this model the properties of objects extending in luminosity from luminous quasars to XRBs. Our general conclusion is that the AGN phenomenology can be accounted for in terms of three parameters: The wind maSS flux in units of the Eddington value, m(dot), the observers' inclination angle Theta and the logarithmic slope between the 0/UV and X-ray fluxes alpha(sub ox); however because of a correlation between alpha(sub ox) and UV luminosity the number of significant parameters is two. The AGN correlations implied by this model appear to extend to and consistent with the XRB phenomenology, suggesting the presence of a truly unified underlying structure for accretion powered sources.

  6. Spectropolarimetry of AGN, and `Women &\\ Science'

    NASA Astrophysics Data System (ADS)

    Kay, L.

    1999-12-01

    I have been using optical spectropolarimetry to investigate the nature of AGN. For the CAREER project, I have worked with A. M. Magalhães of the IAG in Brazil to use a visiting polarimetry module with the RC Spectrograph at CTIO, as well as conduct observations at Lick. Projects include observations of broad--line radio galaxies with double--peaked emission line profiles suggestive of accretion disks, and observations of a sample of X-ray selected narrow--line Seyfert 1 galaxies. Another project involves optical and X-ray observations of a complete sample of nearby Seyfert 2 galaxies in order to investigate the frequency of obscured broad--line regions and to determine their contribution to the X-ray background. In addition to involving undergraduate students in research, my educational efforts have focused on getting science into our Women's Studies program. I teach a course on the history and sociology of women in science, co-teach a course on feminist science studies, helped to create a course on women's health, organized a faculty seminar on gender and science issues, and lead a project at Barnard on gender and scientific literacy. I gratefully acknowledge support from NSF CAREER grant AST-9501835, as well as support from NSF International Research Fellowship INT-9423970, and from NSF grant EHR-9555808 to the AAC&U for the Gender and Scientific Literacy project.

  7. The ensemble optical variability of type-1 AGN in the Sloan Digital Sky Survey Data Release 7

    NASA Astrophysics Data System (ADS)

    Gallastegui-Aizpun, Unai; Sarajedini, Vicki L.

    2014-11-01

    We use a sample of over 5000 active galactic nuclei (AGN) with extended morphologies at z < 0.8 from the Sloan Digital Sky Survey (SDSS) to study the ensemble optical variability as a function of rest-frame time lag and AGN luminosity with the aim of investigating these parameter relationships at lower luminosities than previously studied. We compare photometry from imaging data with spectrophotometry obtained weeks to years later in the Sloan g, r, and i bands. We employ quasar and galaxy eigenspectra fitting to separate the AGN and host galaxy components. A strong correlation between the variability amplitude and rest-frame time lag is observed, in agreement with quasar structure functions but extending to AGN several magnitudes fainter than previously studied. The structure function slopes for our fainter AGN sample are slightly shallower than those found in quasars studies. An anticorrelation with luminosity is clearly detected, with lower luminosity AGN displaying greater variability amplitudes. We demonstrate for the first time that this anticorrelation extends to AGN as faint as MAGNi ˜ -18.5, with a slight trend towards shallower slopes at luminosities fainter than MAGNi ˜ -20.2.

  8. The origin of UV-optical variability in AGN and its relationship to X-ray variability

    NASA Astrophysics Data System (ADS)

    McHardy, I.

    2016-06-01

    The origin of UV-optical variability in AGN remains a major puzzle. Is it driven by some process intrinsic to the accretion disc or by reprocessing of X-rays? If driven by reprocessing, what is doing the reprocessing, a surrounding accretion disc or surrounding gas? Measurement of the lags between the various X-ray, UV and optical bands, and of their relative amplitudes of variability, for a sample of AGN of differing black hole mass and accretion rate, can provide strong constraints on the emission scenarios. For AGN with large mass black holes the lags, assuming disc reprocessing, are of order a day and require intensive monitoring for periods of 1-2 months. Swift may carry out one or 2 such programmes per year. However for lower mass AGN where the expected lags are of order an hour, XMM-Newton, using the OM as well as Epic and in combination with ground based optical observations, can obtain excellent lag measurements with only one or two orbits per AGN. I report on one such programme here. It would therefore be possible, with a large programme, for XMM-Newton to measure lags in a sample of AGN and thus greatly extend our understanding of AGN UV-optical variability.

  9. The Multiwavelength AGN Population and the X-ray Background

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, Claudia M.; Schawinski, Kevin; Simmons, Brooke D.; Natarajan, Priyamvada; Volonteri, Marta

    2014-07-01

    In order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (L X ~ 1044 erg/s) sources (Seyfert-type AGN), at z~ 0.5-1 and in heavily obscured but Compton-thin, NH ~ 1023cm-2, systems. However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We further investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~ 0 to z~ 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth. Finally, we constrain the total accreted mass density in supermassive black holes at z > 6, inferred via the upper limit derived from the integrated X-ray emission from a sample of photometrically selected galaxy candidates. We estimate an accreted mass density <1000 M⊙Mpc-3 at z~ 6, significantly lower than the previous predictions from some existing models of early black hole growth and earlier prior observations.

  10. Are the variability properties of the Kepler AGN light curves consistent with a damped random walk?

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.

    2015-08-01

    We test the consistency of active galactic nuclei (AGN) optical flux variability with the damped random walk (DRW) model. Our sample consists of 20 multiquarter Kepler AGN light curves including both Type 1 and 2 Seyferts, radio-loud and -quiet AGN, quasars, and blazars. Kepler observations of AGN light curves offer a unique insight into the variability properties of AGN light curves because of the very rapid (11.6-28.6 min) and highly uniform rest-frame sampling combined with a photometric precision of 1 part in 105 over a period of 3.5 yr. We categorize the light curves of all 20 objects based on visual similarities and find that the light curves fall into five broad categories. We measure the first-order structure function of these light curves and model the observed light curve with a general broken power-law power spectral density (PSD) characterized by a short-time-scale power-law index γ and turnover time-scale τ. We find that less than half the objects are consistent with a DRW and observe variability on short time-scales (˜2 h). The turnover time-scale τ ranges from ˜10-135 d. Interesting structure function features include pronounced dips on rest-frame time-scales ranging from 10-100 d and varying slopes on different time-scales. The range of observed short-time-scale PSD slopes and the presence of dip and varying slope features suggests that the DRW model may not be appropriate for all AGN. We conclude that AGN variability is a complex phenomenon that requires a more sophisticated statistical treatment.

  11. A New Catalog of Type 1 AGNs and its Implications on the AGN Unified Model

    NASA Astrophysics Data System (ADS)

    Oh, Kyuseok; Yi, Sukyoung K.; Schawinski, Kevin; Koss, Michael; Trakhtenbrot, Benny; Soto, Kurt

    2015-07-01

    We have recently identified a substantial number of type 1 active galactic nuclei (AGNs) featuring weak broad-line regions (BLRs) at z\\lt 0.2 from detailed analysis of galaxy spectra in the Sloan Digital Sky Survey Data Release 7. These objects predominantly show a stellar continuum but also a broad Hα emission line, indicating the presence of a low-luminosity AGN oriented so that we are viewing the central engine directly without significant obscuration. These accreting black holes have previously eluded detection due to their weak nature. The newly discovered BLR AGNs have increased the number of known type 1 AGNs by 49%. Some of these new BLR AGNs were detected with the Chandra X-ray Observatory, and their X-ray properties confirm that they are indeed type 1 AGNs. Based on our new and more complete catalog of type 1 AGNs, we derived the type 1 fraction of AGNs as a function of [O iii] λ 5007 emission luminosity and explored the possible dilution effect on obscured AGNs due to star formation. The new type 1 AGN fraction shows much more complex behavior with respect to black hole mass and bolometric luminosity than has been suggested previously by the existing receding torus model. The type 1 AGN fraction is sensitive to both of these factors, and there seems to be a sweet spot (ridge) in the diagram of black hole mass and bolometric luminosity. Furthermore, we present the possibility that the Eddington ratio plays a role in determining opening angles.

  12. First Detections of Compact AGN-triggered Radio Cores in RQ AGNs in the ECDFS

    NASA Astrophysics Data System (ADS)

    Prandoni, I.; Maini, A.; Norris, R. P.; Giovannini, G.; Spitler, L. R.

    2016-08-01

    The mechanism triggering the radio emission in Radio-Quiet (RQ) Active Galactic Nuclei (AGN), found to be a relevant component of the faint radio population in deep fields, is hotly debated. Most RQ AGNs are unresolved or barely resolved at a few arcsec scale, comparable to the host galaxy size. RQ AGNs have also been found to share many properties with Star Forming Galaxies (SFG). They have similar radio luminosities and similar optical- /infrared-to-radio flux ratios. Their radio luminosity functions show similar evolutionary trends, and their host galaxies have similar colours, optical morphologies and stellar masses. For all these reasons it was concluded that the radio emission in such RQ AGNs is mainly triggered by star formation (SF). However in the local Universe (z<0.5) it is well known that both AGN and SF processes can contribute to the total radio emission in RQ AGNs (see e.g., Seyfert 2 galaxies), and there is growing evidence that composite SF/AGN systems are common at mid to high redshift (z>1-2). We used the Australian Long Baseline Array to observe a number of RQ AGNs in the Extended Chandra Deep Field South (ECDFS), and we detected compact, high-surface-brightness radio cores in some of them. Our pilot study shows that at least some of the sources classified as radio quiet contain an AGN that can contribute significantly (~50% or more) to the total radio emission. This is a first direct evidence of the presence of such AGN-triggered radio emission in RQ AGNs at cosmological redshifts.

  13. AGN Absorption Linked to Host Galaxies

    NASA Astrophysics Data System (ADS)

    Juneau, Stéphanie

    2014-07-01

    Multiwavelength identification of AGN is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity (obscuration, efficiency, etc.). A panchromatic strategy plays an especially important role when the host galaxies are star-forming. Selecting far-Infrared galaxies at 0.3AGN tracers in the X-ray, optical spectra, mid-infrared, and radio regimes, we found a twice higher AGN fraction than previous studies, thanks to the combined AGN identification methods and in particular the recent Mass-Excitation (MEx) diagnostic diagram. We furthermore find an intriguing relation between AGN X-ray absorption and the specific star formation rate (sSFR) of the host galaxies, indicating a physical link between X-ray absorption and either the gas fraction or the gas geometry in the hosts. These findings have implications for our current understanding of both the AGN unification model and the nature of the black hole-galaxy connection.

  14. Looking for the broad emission lines in AGN2 with deep NIR spectroscopy and the measure of the mass of Intermediate Mass BH

    NASA Astrophysics Data System (ADS)

    Onori, Francesca; La Franca, Fabio; Ricci, Federica

    According to the current models of galaxy evolution, in a hierarchical cosmology low mass Black Holes (10 (4) - 10 (7) M_⊙) at low redshift contain clues about the formation of the first Black Holes and Galaxies. Moreover, as they extend the dynamic range of the BH-mass/galaxy scaling relations to extreme values, they could be very useful in constraining the AGN/Galaxy co-evolutionary models. In the past years, in the framework of the verification of the AGN unified model, there have been several attempts to detect faint broad emission lines in type 2 AGN with both NIR and polarised spectroscopy. We here present the new results from a systematic study, performed using deep NIR (VLT and LBT) spectroscopy, of about 50 AGN2, drawn from the complete SWIFT/BAT 22-month had X-ray selected sample. A new virial relation able to measure the BH mass using the broad component of the Paschenbeta line will be also presented. Thanks to the above relation we have been able to directly measure, when the BLR has been detected, the BH mass of type 2 AGNs, finding that AGN2 show on average lower masses than the AGN1 population. The implications to the AGN unified model and AGN/galaxy co-evolution scenarios will be discussed.

  15. A method for determining AGN accretion phase in field galaxies

    NASA Astrophysics Data System (ADS)

    Micic, Miroslav; Martinović, Nemanja; Sinha, Manodeep

    2016-09-01

    Recent observations of active galactic nucleus (AGN) activity in massive galaxies (log M*/ M⊙ > 10.4) show the following: (1) at z < 1, AGN-hosting galaxies do not show enhanced merger signatures compared with normal galaxies, (2) also at z < 1, most AGNs are hosted by quiescent galaxies and (3) at z > 1, the percentage of AGNs in star-forming galaxies increases and becomes comparable to the AGN percentage in quiescent galaxies at z ˜ 2. How can major mergers explain AGN activity in massive quiescent galaxies that have no merger features and no star formation to indicate a recent galaxy merger? By matching merger events in a cosmological N-body simulation to the observed AGN incidence probability in the COSMOS survey, we show that major merger-triggered AGN activity is consistent with the observations. By distinguishing between `peak' AGNs (recently merger-triggered and hosted by star-forming galaxies) and `faded' AGNs (merger-triggered a long time ago and now residing in quiescent galaxies), we show that the AGN occupation fraction in star-forming and quiescent galaxies simply follows the evolution of the galaxy merger rate. Since the galaxy merger rate drops dramatically at z < 1, the only AGNs left to be observed are the ones triggered by old mergers that are now in the declining phase of their nuclear activity, hosted by quiescent galaxies. As we go towards higher redshifts, the galaxy merger rate increases and the percentages of `peak' AGNs and `faded' AGNs become comparable.

  16. Nebular emission from AGN in the ultraviolet/optical: diagnostics of the ionizing source and gas properties

    NASA Astrophysics Data System (ADS)

    Feltre, A.

    2016-08-01

    Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, forthcoming facilities such as JWST and the E-ELT, will provide rest-frame ultraviolet and optical spectra of the very distant AGN. To lay the groundwork for the interpretation of these revolutionary datasets, we have recently computed new photoionization models of the narrow-line emitting regions (NLR) of AGN and combined them with similar models of the nebular emission from star-forming galaxies. In this talk, I will first describe how new ultraviolet and standard optical spectral diagnostics allow one to distinguish between nuclear activity and star formation. I will then explain how predictions of AGN nebular emission can be best used to understand the physical properties of the AGN NLR gas. In particular, I will present recent results from a study on one of the most comprehensive set of optical spectra (from VIMOS/VLT) sampling the rest-frame ultraviolet range of ~90 type 2 AGN (1.5 < z < 3), drawn from the z-COSMOS deep survey. To conclude, I will show how the implementation of AGN photoionization calculations in an innovative Bayesian fitting code can help us best interpret current, and future, spectro-photometric data on active galaxies.

  17. Nuclear stellar kinematics of hard X-ray selected AGNs with matched inactive galaxies

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Yin; Davies, Richard; Burtscher, Leonard; Rosario, David

    2016-08-01

    In a matched sample of local, 14-195 keV selected active galactic nuclei (AGN) and inactive galaxies, we investigate the spatially resolved stellar kinematics and distributions on the scale of 10-300 pc. Here we present first results on part of the sample. We use a simple model to look for non-circular motions in the observed stellar velocity fields of both AGNs and inactive galaxies. Combining the luminosity profile with larger scale data, we decompose the large-scale disk, bulge and nuclear components. And with the stellar velocity dispersion, we search for the evidence of dynamically cold nuclear stellar populations distinct from the bulge, and study the nuclear K-band stellar mass to light ratios. The key goal of this study is to understand the role of nuclear star formation in the AGN fueling process.

  18. The host galaxies of radio-loud and radio-quiet AGNs

    NASA Astrophysics Data System (ADS)

    Koziel-Wierzbowska, D.; Vale Asari, N.; Stasinska, G.; Sikora, M.

    2016-08-01

    To infer whether the jet production efficiency depends on the host properties or is determined just by intrinsic properties of the accretion flows we compared optical properties of the host galaxies of radio-quiet (RQ) and radio-loud (RL) Type 2 AGNs. We carefully selected galaxies from SDSS, FIRST, and NVSS catalogues. We confirmed that the fraction of RL AGNs increases with the black hole (BH) masses and decreases with the Eddington ratio. Therefore, the comparison of the nature of the hosts of RL and RQ AGNs requires pairmatching techniques. By pairing RL and RQ samples in BH mass, Eddington ratio and redshift, we showed that the radio-loudness correlates with the host-galaxy concentration index and morphological type, and anti-correlates with the recent specific star-formation rate and dust attenuation. Contrary to some previous studies, we found no significant difference between our radio-loud and radio-quiet samples regarding merger/interaction features.

  19. The Kepler Light Curves of KSwAGS AGN: A Unique Window into Accretion Physics

    NASA Astrophysics Data System (ADS)

    Smith, Krista Lynne; Mushotzky, Richard; Boyd, Padi; Edelson, Rick; Howell, Steve; Gelino, Dawn; Brown, Alex

    2016-08-01

    The Kepler-Swift Active Galaxies Survey (KSwAGS) discovered ~160 AGN in the Kepler and K2 fields. The optical Kepler and K2 light curves of these AGN are by far the most precise and evenly-sampled ever obtained. There are unique challenges involved in adapting Kepler/K2 data for use with AGN since the Kepler pipeline removes stochasticity; however, once mitigated, these data provide an unprecedented glimpse of the accretion disk's variability. We have also conducted follow-up spectral observations to determine black hole masses and accretion rates for the sample, which fill a wide parameter space (6.9 < Log MBH < 9.4, 0.003 < L/Ledd < 0.6). These, in tandem with the light curves, may be able to distinguish between different accretion models.

  20. The eROSITA/SRG All-Sky Survey: A new era of large-scale structure studies with AGN

    NASA Astrophysics Data System (ADS)

    Kolodzig, A.; Gilfanov, M.; H"utsi, G.; Sunyaev, R.

    2014-07-01

    The four-year X-ray all-sky survey (eRASS) of the eROSITA telescope aboard the Spektrum-Roentgen-Gamma (SRG) satellite will detect ˜3 million active galactic nuclei (AGN) with a median redshift of z≈1 and typical luminosity of L_{0.5-2.0keV}˜10^{44} erg s^{-1}. We show that this unprecedented AGN sample, complemented with redshift information, will supply us with outstanding opportunities for large-scale structure research. For the first time with a sample of X-ray selected AGN, it will become possible to perform detailed redshift- and luminosity-resolved studies of the linear bias factor. These studies will dramatically improve our understanding of AGN environment, triggering mechanisms, growth of super-massive black holes and their co-evolution with dark matter halos. The eROSITA AGN sample will become a powerful cosmological probe. It will become possible to convincingly detect baryonic acoustic oscillations (BAOs) with ˜8σ confidence in the 0.8AGN sample, photometric and spectroscopic surveys of large areas and a sufficient depth will be needed.

  1. The OPTX Project. IV. How Reliable is [O III] as a Measure of AGN Activity?

    NASA Astrophysics Data System (ADS)

    Trouille, L.; Barger, A. J.

    2010-10-01

    We compare optical and hard X-ray identifications of active galactic nuclei (AGNs) using a uniformly selected (above a flux limit of f 2-8 keV = 3.5 × 10-15 erg cm-2 s-1) and highly optically spectroscopically complete (>80% for f 2-8 keV > 10-14 erg cm-2 s-1 and >60% below) 2-8 keV sample observed in three Chandra fields (CLANS, CLASXS, and the CDF-N). We find that empirical emission-line ratio diagnostic diagrams misidentify 50% of the X-ray-selected AGNs that can be put on these diagrams as star formers. We confirm that there is a large (two orders of magnitude) dispersion in the ratio of the [O III]λ5007 (hereafter [O III]) to hard X-ray luminosities for the non-broad-line AGNs, even after applying reddening corrections to the [O III] luminosities. We find that the dispersion is similar for the broad-line AGNs, where there is not expected to be much X-ray absorption from an obscuring torus around the AGN nor much obscuration from the galaxy along the line of sight if the AGN is aligned with the galaxy. We postulate that the X-ray-selected AGNs that are misidentified by the diagnostic diagrams have low [O III] luminosities due to the complexity of the structure of the narrow-line region, which causes many ionizing photons from the AGN not to be absorbed. This would mean that the [O III] luminosity can only be used to predict the X-ray luminosity to within a factor of ~3 (1σ). Despite selection effects, we show that the shapes and normalizations of the [O III] and transformed hard X-ray luminosity functions show reasonable agreement, suggesting that the [O III] samples are not finding substantially more AGNs at low redshifts than hard X-ray samples. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial

  2. Prevalence of galaxy-galaxy interactions in AGN hosts

    NASA Astrophysics Data System (ADS)

    Lim, Jeremy; Kuo, Cheng-Yu; Tang, Ya-Wen; Greene, Jenny; Ho, Paul T. P.

    2004-11-01

    Studies in optical starlight have failed to reach a consensus on the importance of either galaxy interactions, bars, or nuclear spirals in triggering luminous active galactic nuclei (AGNs). Here, we present the first systematic imaging study of Seyfert (disk) galaxies in the 21-cm line of neutral atomic hydrogen (HI) gas. HI is the most sensitive and enduring tracer of galaxy interactions, and can reveal tidal features not otherwise visible in optical starlight. Our sample comprises all twenty-eight galaxies in the Véron-Cetty & Véron (1998) catalog with nuclear magnitudes -19 ≥ MB > -23 (including Seyfert, LINER, and HII galaxies) at 0.015 ≤ z ≤ 0.017 in the northern hemisphere, and a matched control sample of twenty-seven inactive galaxies at z≈0.008. We have detected nearly all the galaxies observed, and find a much higher incidence of tidal interactions -- usually not seen in optical starlight -- among the Seyfert galaxies by comparison with the matched control sample. Those Seyferts with uncertain or no clear tidal features show disturbed HI morphologies and/or kinematics, as well as HI companion galaxies, more frequently than the control sample. Our study suggests that the undisturbed optical appearence of active galaxies may be deceptive, and imply that galaxy-galaxy interactions trigger a significant fraction luminous AGNs at low redshifts. The majority of the Seyfert galaxies in our sample appear to be at a relatively early stage of an encounter rather than late in a merger.

  3. Obscuring Torus Geometry from the NuSTAR Survey of Swift/BAT AGN

    NASA Astrophysics Data System (ADS)

    Balokovic, Mislav; Harrison, Fiona; NuSTAR

    2016-06-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the spectral window above 10 keV with unprecedented spatial resolution and two orders of magnitude better sensitivity than any other instrument operating in that energy range. As a part of its long-term extragalactic program NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT). I will present spectroscopic results based on NuSTAR and Swift observations of ~150 Swift/BAT AGN surveyed in the first three years of NuSTAR operation. This sample forms an atlas of the highest quality hard X-ray spectra available to date for a large number of AGN, providing unprecedented insight into the variety AGN spectra in the hard X-ray band. In addition to phenomenology, which is an essential ingredient of Cosmic X-ray Background studies, it is possible to use new fitting models to directly probe the geometry of the toroidal obscurer (torus). Its main spectral features lie within the NuSTAR bandpass, making it possible to test the common assumption that a similar Compton-thick torus exists around essentially every Seyfert-type AGN. I will discuss torus geometry constraints based on the X-ray spectra in relation to those from other wavelengths, the effects on interpretation of high-redshift AGN observations, and the limitations of the current results.

  4. Retired galaxies: not to be forgotten in the quest of the star formation - AGN connection

    NASA Astrophysics Data System (ADS)

    Stasińska, G.; Costa-Duarte, M. V.; Vale Asari, N.; Cid Fernandes, R.; Sodré, L.

    2015-05-01

    We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with M⋆ > 1011.5 M⊙ have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than 1010 M⊙. We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments - i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1-5 Gyr for detectable AGN in galaxies with masses between 1010-1012 M⊙. The lifetimes of the AGN-dominated phases are a few 108 yr. Finally, we compare the star formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on, it inhibits star formation for the next ˜0.1 Gyr in galaxies with masses around 1010 M⊙, ˜ 1 Gyr in galaxies with masses around 1011 M⊙.

  5. GT1_pbarthel_1: The Herschel Legacy of distant radio-loud AGN

    NASA Astrophysics Data System (ADS)

    Barthel, P.

    2010-03-01

    We propose Herschel observations of the virtually complete sample of 3CR radio-galaxies and quasars in the redshift range 1 < z < 2.5, and a representative additional set of 4C objects extending to redshift z = 3, in order to quantify the orientation-dependence of AGN radiation (AGN unification), to investigate the interplay between accretion onto the central black-hole and star-formation in the hosts, to understand the evolution of the black-hole/stellar-bulge relation, and to make the first accurate assay of the energetics of AGN at the epoch of their peak activity, the quasar era. The low-frequency radio-selection provides us with very powerful and massive active galaxies free from any orientation/obscuration bias, a requirement for testing AGN unification. The properties of particularly the high-z 3CR sources are well known throughout the electromagnetic spectrum, except in the rest-frame mid- and far-IR, where they were hitherto outside the reach of space missions. We propose PACS/SPIRE 70-500 micron photometry of 71 3CR+4C sources in 5 bands, in order to measure their detailed spectral energy distributions between available Spitzer and SCUBA/MAMBO data. The rest-frame FIR emission serves as an isotropic calorimeter and the MIR/FIR luminosity ratio is determined by the relative strength of the AGN and star-forming contributions combined with dust obscuration. These observations will return crucial new information on the energy processes in powerful AGN and their hosts at the cosmic heyday, providing an essential anchor for studies of galaxy and AGN evolution.

  6. Evidence for Distributed Young Stellar Populations in Strong AGN at z 1

    NASA Astrophysics Data System (ADS)

    Ammons, Mark; Melbourne, J.; Koo, D.; Max, C.

    2008-09-01

    We present stellar populations analysis of 8 AGN hosts at z 1 and derive stellar age trends that compare to local AGN host samples. We utilize laser guide star adaptive optics imaging in K-band, taken at the Keck Observatory, of hosts in the Great Observatories Origins Deep Survey (GOODS) South. Combination of these data with imaging in B, V, i, z from the HST Advanced Camera for Surveys (ACS) gives multi-color photometry with comparable spatial resolution of better than 100 mas in all bands. The AGN nature of these hosts is implied from their large X-ray luminosities (log L > 42 in ergs/s, 2-10 keV) as measured by Chandra. We fit Bruzual & Charlot (2003) stellar populations models to the 5-band photometry. Our use of near-IR fluxes in the fitting process gives tighter constraints on the dust extinction. The strongest conclusion is that the presence of distributed younger stellar populations (age less than 100 Myr) is correlated with the [OIII] line luminosity or X-ray (2-10 keV) luminosity. This finding is consistent with similar studies at lower redshift. However, we also find that strong Type II AGN hosts at this redshift are more likely to have some disk component or be irregulars than all Type I sources, which tend to be of earlier type. The mid-IR SEDs of the strong Type II AGN indicates that they are excited to LIRG status via galactic starbursting, while the strong Type I AGN are excited to LIRG status via hot dust surrounding the central engine. This suggests that the obscured nature of Type II AGN at this redshift is connected with global starbursting and that they may be extincted by kpc-scale dusty features that are byproducts of this starbursting. This study is funded by the Bachmann family and the NSF.

  7. The SRG/eROSITA All-Sky Survey: A new era of large-scale structure studies with AGN

    NASA Astrophysics Data System (ADS)

    Kolodzig, Alexander; Gilfanov, Marat; Hütsi, Gert; Sunyaev, Rashid

    2015-08-01

    The four-year X-ray All-Sky Survey (eRASS) of the eROSITA telescope aboard the Spektrum-Roentgen-Gamma (SRG) satellite will detect about 3 million active galactic nuclei (AGN) with a median redshift of z~1 and typical luminosity of L0.5-2.0keV ~ 1044 erg/s. We demonstrate that this unprecedented AGN sample, complemented with redshift information, will supply us with outstanding opportunities for large-scale structure (LSS) studies.We show that with this sample of X-ray selected AGN, it will become possible for the first time to perform detailed redshift- and luminosity-resolved studies of the AGN clustering. This enable us to put strong constraints on different AGN triggering/fueling models as a function of AGN environment, which will dramatically improve our understanding of super-massive black hole growth and its correlation with the co-evolving LSS.Further, the eRASS AGN sample will become a powerful cosmological probe. We demonstrate for the first time that, given the breadth and depth of eRASS, it will become possible to convincingly detect baryonic acoustic oscillations (BAOs) with ~8σ confidence in the 0.8 < z < 2.0 range, currently uncovered by any existing BAO survey.Finally, we discuss the requirements for follow-up missions and demonstrate that in order to fully exploit the potential of the eRASS AGN sample, photometric and spectroscopic surveys of large areas and a sufficient depth will be needed.

  8. Spherical accretion and AGN feedback

    NASA Astrophysics Data System (ADS)

    Nulsen, Paul

    2014-06-01

    For a supermassive black hole accreting from a hot, quasi-spherical atmosphere, it is almost inevitable that the fluid approximation fails inside some point within the Bondi radius, but well outside the black hole event horizon. Within the region where the particle mean free paths exceed the radius, the flow must be modeled in terms of the Fokker-Planck equation. In the absence of magnetic fields, it is analogous to the "loss cone" problem for consumption of stars by a black hole. The accretion rate is suppressed well below the Bondi accretion rate and a significant power must be conveyed outward for the flow to proceed. This situation is complicated significantly by the presence of a magnetic field, but I will argue that the main outcomes are similar. I will also argue that the power emerging from such a flow, although generally far too little to suppress cooling on large scales, is an important ingredient of the AGN feedback cycle on scales comparable to the Bondi radius.

  9. Early evolution stage of AGN

    NASA Astrophysics Data System (ADS)

    Kunert-Bajraszewska, M.; Labiano, A.; Siemiginowska, A.; Guainazzi, M.; Gawroński, M.

    2015-03-01

    Radio sources are divided into two distinct morphological groups of objects: Fanaroff-Riley type I and type II sources. There is a relatively sharp luminosity boundary between these at low frequency. The nature of the FR division is still an open issue, as are the details of the evolutionary process in which younger and smaller GHz-peaked spectrum (GPS) and compact steep spectrum (CSS) sources become large-scale radio structures. It is still unclear whether FRII objects evolve to become FRIs, or whether a division has already occurred amongst CSS sources and some of these then become FRIs and some FRIIs. We explored evolution scenarios of AGNs using new radio, optical and X-ray data of unstudied so far Low Luminosity Compact (LLC) sources. We suggest that the determining factors of the further evolution of compact radio objects could occur at subgalactic (or even nuclear) scales, or they could be related to the radio jet - interstellar medium (ISM) interactions and evolution. Our studies show that the evolutionary track could be related to the interaction, strength of the radio source and excitation levels of the ionized gas instead of the radio morphology of the young radio source.

  10. Gas phase synthesis and reactivity of Agn+ and Ag(n-1)H+ cluster cations.

    PubMed

    Khairallah, George N; O'Hair, Richard A J

    2005-08-21

    Multi-stage mass spectrometry (MSn) on [(M + Ag - H)x + Ag]+ precursor ions (where M = an amino acid such as glycine or N,N-dimethylglycine) results in the formation of stable silver (Ag3+, Ag5+ and Ag7+) and silver hydride (Ag2H+, Ag4H+ and Ag6H+) cluster cations in the gas phase. Deuterium labelling studies reveal that the source of the hydride can be either from the alpha carbon or from one of the heteroatoms. When M = glycine, the silver cyanide clusters Ag4CN+ and Ag5(H,C,N)+ are also observed. Collision induced dissociation (CID) and DFT calculations were carried out on each of these clusters to shed some light on their possible structures. CID of the Agn+ and Ag(n-1)H+ clusters generally results in the formation of the same Ag(n-2)+ product ions via the loss of Ag2 and AgH respectively. DFT calculations also reveal that the Agn+ and Ag(n-1)H+ clusters have similar structural features and that the Ag(n-1)H+ clusters are only slightly less stable than their all silver counterparts. In addition, Agn+ and Ag(n-1)H+ clusters react with 2-propanol and 2-butylamine via similar pathways, with multiple ligand addition occurring and a coupled deamination-dehydration reaction occurring upon condensation of a third (for Ag2H+) or a fourth (for all other silver clusters) 2-butylamine molecule onto the clusters. Taken together, these results suggest that the Agn+ and Ag(n-1)H+ clusters are structurally related via the replacement of a silver atom with a hydrogen atom. This replacement does not dramatically alter the cluster stability or its unimolecular or bimolecular chemistry with the 2-propanol and 2-butylamine reagents.

  11. Higher prevalence of X-ray selected AGN in intermediate-age galaxies up to z ˜ 1

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio; Alonso-Herrero, Almudena; Pérez-González, Pablo G.; Barro, Guillermo; Aird, James; Ferreras, Ignacio; Cava, Antonio; Cardiel, Nicolás; Esquej, Pilar; Gallego, Jesús; Nandra, Kirpal; Rodríguez-Zaurín, Javier

    2014-10-01

    We analyse the stellar populations in the host galaxies of 53 X-ray selected optically dull active galactic nuclei (AGN) at 0.34 < z < 1.07 with ultradeep (mAB = 26.5, 3σ) optical medium-band (R ˜ 50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 Å break, Dn(4000), a reliable age indicator for stellar populations. We confirm that most X-ray selected moderate-luminosity AGN (LX < 1044 erg s-1) are hosted by massive galaxies (typically M* >1010.5 M⊙) and that the observed fraction of galaxies hosting an AGN increases with the stellar mass. A careful selection of random control samples of inactive galaxies allows us to remove the stellar mass and redshift dependences of the AGN fraction to explore trends with several stellar age indicators. We find no significant differences in the distribution of the rest-frame U - V colour for AGN hosts and inactive galaxies, in agreement with previous results. However, we find significantly shallower 4000 Å breaks in AGN hosts, indicative of younger stellar populations. With the help of a model-independent determination of the extinction, we obtain extinction-corrected U - V colours and light-weighted average stellar ages. We find that AGN hosts have younger stellar populations and higher extinction compared to inactive galaxies with the same stellar mass and at the same redshift. We find a highly significant excess of AGN hosts with Dn(4000) ˜ 1.4 and light-weighted average stellar ages of 300-500 Myr, as well as a deficit of AGN in intrinsic red galaxies. We interpret failure in recognizing these trends in previous studies as a consequence of the balancing effect in observed colours of the age-extinction degeneracy.

  12. CANDELS: CONSTRAINING THE AGN-MERGER CONNECTION WITH HOST MORPHOLOGIES AT z {approx} 2

    SciTech Connect

    Kocevski, Dale D.; Faber, S. M.; Mozena, Mark; Trump, Jonathan R.; Koo, David C.; Nandra, Kirpal; Brusa, Marcella; Wuyts, Stijn; Rangel, Cyprian; Laird, Elise S.; Bell, Eric F.; Alexander, David M.; Bournaud, Frederic; Conselice, Christopher J.; Dekel, Avishai; and others

    2012-01-10

    Using Hubble Space Telescope/WFC3 imaging taken as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we examine the role that major galaxy mergers play in triggering active galactic nucleus (AGN) activity at z {approx} 2. Our sample consists of 72 moderate-luminosity (L{sub X} {approx} 10{sup 42-44} erg s{sup -1}) AGNs at 1.5 < z < 2.5 that are selected using the 4 Ms Chandra observations in the Chandra Deep Field South, the deepest X-ray observations to date. Employing visual classifications, we have analyzed the rest-frame optical morphologies of the AGN host galaxies and compared them to a mass-matched control sample of 216 non-active galaxies at the same redshift. We find that most of the AGNs reside in disk galaxies (51.4{sup +5.8}{sub -5.9}%), while a smaller percentage are found in spheroids (27.8{sup +5.8}{sub -4.6}%). Roughly 16.7{sup +5.3}{sub -3.5}% of the AGN hosts have highly disturbed morphologies and appear to be involved in a major merger or interaction, while most of the hosts (55.6{sup +5.6}{sub -5.9}%) appear relatively relaxed and undisturbed. These fractions are statistically consistent with the fraction of control galaxies that show similar morphological disturbances. These results suggest that the hosts of moderate-luminosity AGNs are no more likely to be involved in an ongoing merger or interaction relative to non-active galaxies of similar mass at z {approx} 2. The high disk fraction observed among the AGN hosts also appears to be at odds with predictions that merger-driven accretion should be the dominant AGN fueling mode at z {approx} 2, even at moderate X-ray luminosities. Although we cannot rule out that minor mergers are responsible for triggering these systems, the presence of a large population of relatively undisturbed disk-like hosts suggests that the stochastic accretion of gas plays a greater role in fueling AGN activity at z {approx} 2 than previously thought.

  13. Dramatic long-term X-ray variability in AGNs

    NASA Astrophysics Data System (ADS)

    Moran, Edward C.

    2016-04-01

    Dramatic X-ray and optical variability on ˜ 10 year timescales has been discovered recently in a handful of quasars, which may provide important new insight into the issue of how luminous AGNs are fueled. We have assembled a new sample of extremely variable X-ray sources from archival Einstein and ROSAT data that could increase substantially the number of such objects known. The sources in our sample varied in X-ray flux by at least a factor of 7-8 over a 10-year span, and most exhibited significantly larger variability amplitudes (10 to over 100). We present the details of how our sample was assembled and preliminary results regarding the identifications, properties, and X-ray histories of the objects. Although a heterogeneous population is expected, some sources in the sample are associated with broad-line AGNs, including a radio-quiet quasar at z = 1.3 that decreased in X-ray luminosity by a factor of 40.

  14. Eddington ratios of faint AGN at intermediate redshift: evidence for a population of half-starved black holes

    NASA Astrophysics Data System (ADS)

    Gavignaud, I.; Wisotzki, L.; Bongiorno, A.; Paltani, S.; Zamorani, G.; Møller, P.; Le Brun, V.; Husemann, B.; Lamareille, F.; Schramm, M.; Le Fèvre, O.; Bottini, D.; Garilli, B.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Bondi, M.; Busarello, G.; Cucciati, O.; de La Torre, S.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.; Vergani, D.

    2008-12-01

    We use one of the deepest spectroscopic samples of broad-line active galactic nuclei (AGN) currently available, extracted from the VIMOS VLT Deep Survey (VVDS), to compute the Mg II and C IV virial-mass estimates of 120 super-massive black holes in the redshift range 1.0AGN luminosities (log L_bol ˜ 45). At these luminosities, there is a substantial fraction of black holes accreting far below their Eddington limit (L_bol/L_Edd < 0.1), in marked contrast to what is generally found for AGN of higher luminosities. We speculate that these may be AGN on the decaying branch of their lightcurves, well past their peak activity. This would agree with recent theoretical predictions of AGN evolution. In the electronic Appendix of this paper we publish an update of the VVDS type-1 AGN sample, including the first and most of the second-epoch observations. This sample contains 298 objects of which 168 are new. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007(A), 272.A-5047, 076.A-0808, and partially on data obtained at the Canada-France-Hawaii Telescope.

  15. Long-Term Variability of AGN at Hard X-Rays

    NASA Technical Reports Server (NTRS)

    Soldi, S.; Beckmann, V.; Baumgartner W. H.; Ponti, G.; Shrader, C. R.; Lubinski, P.; Krimm, H. A.; Mattana, F.; Tueller, J.

    2013-01-01

    Variability at all observed wavelengths is a distinctive property of active galactic nuclei (AGN). Hard X-rays provide us with a view of the innermost regions of AGN, mostly unbiased by absorption along the line of sight. Characterizing the intrinsic hard X-ray variability of a large AGN sample and comparing it to the results obtained at lower X-ray energies can significantly contribute to our understanding of the mechanisms underlying the high-energy radiation. Methods. Swift/BAT provides us with the unique opportunity to follow, on time scales of days to years and with a regular sampling, the 14-195 keV emission of the largest AGN sample available up to date for this kind of investigation. As a continuation of an early work on the first 9 months of BAT data, we study the amplitude of the variations, and their dependence on sub-class and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey. About 80 of the AGN in the sample are found to exhibit significant variability on months to years time scales, radio loud sources being the most variable. The amplitude of the variations and their energy dependence are incompatible with variability being driven at hard X-rays by changes of the absorption column density. In general, the variations in the 14-24 and 35-100 keV bands are well correlated, suggesting a common origin of the variability across the BAT energy band. However, radio quiet AGN display on average 10 larger variations at 14-24 keV than at 35-100 keV and a softer-when-brighter behavior for most of the Seyfert galaxies with detectable spectral variability on month time scale. In addition, sources with harder spectra are found to be more variable than softer ones. These properties are generally consistent with a variable power law continuum, in flux and shape, pivoting at energies 50 keV, to which a constant reflection component is superposed. When the same time scales are considered, the timing properties of AGN at

  16. Statistical Properties of Local AGNs Inferred from the RXTE 3-20 keV All-Sky Survey

    NASA Astrophysics Data System (ADS)

    Revnivtsev, M.; Sazonov, S. Yu.

    We have recently ([1]) performed an all-sky survey in the 3-20 keV band from the data accumulated during satellite slews in 1996-2002 - the RXTE slew survey (XSS). For 90% of the sky at |b|>10° , a flux limit for source detection of 2.5×10-11 erg/s/sq.cm(3-20 keV) or lower was achieved, while a combined area of 7000 sq.deg was sampled to record flux levels (for such very large-area surveys) below 10-11 erg/s/sq.cm. A catalog contains 294 X-ray sources. 236 of these sources were identified with a single known astronomical object. Of particular interest are 100 identified active galactic nuclei (AGNs) and 35 unidentified sources. The hard spectra of the latter suggest that many of them will probably also prove AGNs when follow-up observations are performed. Most of the detected AGNs belong to the local population (z<0.1). In addition, the hard X-ray band of the XSS (3-20 keV) as compared to most previous X-ray surveys, performed at photon energies below 10 keV, has made possible the detection of a substantial number of X-ray absorbed AGNs (mostly Seyfert 2 galaxies). These properties make the XSS sample of AGNs a valuable one for the study of the local population of AGNs. We carried out a thorough statistical analysis of the above sample in order to investigate several key properties of the local population of AGNs, in particular their distribution in intrinsic absorption column density (NH) and X-ray luminosity function ([2]). Knowledge of these characteristics provides important constraints for AGN unification models and synthesis of the cosmic X-ray background, and is further needed to understand the details of the accretion-driven growth of supermassive black holes in the nuclei of galaxies.

  17. A tale of two feedbacks: Star formation in the host galaxies of radio AGNs

    SciTech Connect

    Karouzos, Marios; Im, Myungshin; Jeon, Yiseul; Kim, Ji Hoon; Trichas, Markos; Goto, Tomo; Malkan, Matt; Ruiz, Angel; Lee, Hyung Mok; Kim, Seong Jin; Oi, Nagisa; Matsuhara, Hideo; Takagi, Toshinobu; Murata, K.; Wada, Takehiko; Wada, Kensuke; Shim, Hyunjin; Hanami, Hitoshi; Serjeant, Stephen; White, Glenn J.; and others

    2014-04-01

    Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect star formation. We use a sample of radio sources in the North Ecliptic Pole (NEP) field to study the nature of this putative link, by means of spectral energy distribution (SED) fitting. We employ the excellent spectral coverage of the AKARI infrared space telescope and the rich ancillary data available in the NEP to build SEDs extending from UV to far-IR wavelengths. We find a significant AGN component in our sample of relatively faint radio sources (AGN component and that of star formation in the host galaxy, independent of the radio luminosity. In contrast, for narrow redshift and AGN luminosity ranges, we find that increasing radio luminosity leads to a decrease in the specific star formation rate. The most radio-loud AGNs are found to lie on the main sequence of star formation for their respective redshifts. For the first time, we potentially see such a two-sided feedback process in the same sample. We discuss the possible suppression of star formation, but not total quenching, in systems with strong radio jets, that supports the maintenance nature of feedback from radio AGN jets.

  18. Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey

    SciTech Connect

    de Vries, W H; Hodge, J A; Becker, R H; White, R L; Helfand, D J

    2007-04-18

    We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength of the 4000{angstrom} break. We detect a strong trend for sources that are actively undergoing star-formation to have excess radio emission beyond the {approx} 10{sup 28} ergs s{sup -1} Hz{sup -1} level found for sources without any discernible star-formation. Furthermore, this additional radio emission correlates well with the strength of the 4000{angstrom} break in the optical spectrum, and may be used to assess the age of the star-forming component. We examine two subsamples, one containing the systems with emission line ratios most like star-forming systems, and one with the sources that have characteristic AGN ratios. This division also separates the mechanism responsible for the radio emission (star-formation vs. AGN). For both cases we find a strong, almost identical, correlation between [O III] and radio luminosity, with the AGN sample extending toward lower, and the star-formation sample toward higher luminosities. A clearer separation between the two subsamples is seen as function of the central velocity dispersion {sigma} of the host galaxy. For systems at similar redshifts and values of {sigma}, the star-formation subsample is brighter than the AGN in the radio by an order of magnitude. This underlines the notion that the radio emission in star-forming systems can dominate the emission associated with the AGN.

  19. THE XMM-NEWTON WIDE FIELD SURVEY IN THE COSMOS FIELD: REDSHIFT EVOLUTION OF AGN BIAS AND SUBDOMINANT ROLE OF MERGERS IN TRIGGERING MODERATE-LUMINOSITY AGNs AT REDSHIFTS UP TO 2.2

    SciTech Connect

    Allevato, V.; Hasinger, G.; Salvato, M.; Finoguenov, A.; Brusa, M.; Bongiorno, A.; Merloni, A.; Cappelluti, N.; Miyaji, T.; Gilli, R.; Zamorani, G.; Comastri, A.; Shankar, F.; James, J. B.; Peacock, J. A.; McCracken, H. J.; Silverman, J.

    2011-08-01

    We present a study of the redshift evolution of the projected correlation function of 593 X-ray selected active galactic nuclei (AGNs) with I{sub AB} < 23 and spectroscopic redshifts z < 4, extracted from the 0.5-2 keV X-ray mosaic of the 2.13 deg{sup 2} XMM- Cosmic Evolution Survey (COSMOS). We introduce a method to estimate the average bias of the AGN sample and the mass of AGN hosting halos, solving the sample variance using the halo model and taking into account the growth of the structure over time. We find evidence of a redshift evolution of the bias factor for the total population of XMM-COSMOS AGNs from b-bar (z-bar =0.92)=2.30{+-}0.11 to b-bar (z-bar =1.94)=4.37{+-}0.27 with an average mass of the hosting dark matter (DM) halos log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.12 {+-} 0.12 that remains constant at all z < 2. Splitting our sample into broad optical line AGNs (BL), AGNs without broad optical lines (NL), and X-ray unobscured and obscured AGNs, we observe an increase of the bias with redshift in the range z-bar = 0.7-2.25 and z-bar = 0.6-1.5 which corresponds to a constant halo mass of log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.28 {+-} 0.07 and log M{sub 0}(h{sup -1} M{sub sun}) {approx} 13.00 {+-} 0.06 for BL/X-ray unobscured AGNs and NL/X-ray obscured AGNs, respectively. The theoretical models, which assume a quasar phase triggered by major mergers, cannot reproduce the high bias factors and DM halo masses found for X-ray selected BL AGNs with L{sub BOL} {approx} 2 x 10{sup 45} erg s{sup -1}. Our work extends up to z {approx} 2.2 the z {approx}< 1 statement that, for moderate-luminosity X-ray selected BL AGNs, the contribution from major mergers is outnumbered by other processes, possibly secular ones such as tidal disruptions or disk instabilities.

  20. Cosmology with AGN dust time lags - Simulating the new VEILS survey

    NASA Astrophysics Data System (ADS)

    Hönig, S. F.; Watson, D.; Kishimoto, M.; Gandhi, P.; Goad, M.; Horne, K.; Shankar, F.; Banerji, M.; Boulderstone, B.; Jarvis, M.; Smith, M.; Sullivan, M.

    2016-10-01

    The time lag between optical and near-infrared continuum emission in active galactic nuclei (AGN) shows a tight correlation with luminosity and has been proposed as a standardisable candle for cosmology. In this paper, we explore the use of these AGN hot-dust time lags for cosmological model fitting under the constraints of the new VISTA Extragalactic Infrared Legacy Survey VEILS. This new survey will target a 9 deg2 field observed in J- and Ks-band with a 14-day cadence and will run for three years. The same area will be covered simultaneously in the optical griz bands by the Dark Energy Survey, providing complementary time-domain optical data. We perform realistic simulations of the survey setup, showing that we expect to recover dust time lags for about 450 objects out of a total of 1350 optical type 1 AGN, spanning a redshift range of 0.1 < z < 1.2. We use the lags recovered from our simulations to calculate precise distance moduli, establish a Hubble diagram, and fit cosmological models. Assuming realistic scatter in the distribution of the dust around the AGN as well as in the normalisation of the lag-luminosity relation, we are able to constrain Ω _Λ in ΛCDM with similar accuracy as current supernova samples. We discuss the benefits of combining AGN and supernovae for cosmology and connect the present work to future attempts to reach out to redshifts of z > 4.

  1. Disentangling AGN and Star Formation Activity at High Redshift Using Hubble Space Telescope Grism Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bridge, Joanna S.; Zeimann, Gregory R.; Trump, Jonathan R.; Gronwall, Caryl; Ciardullo, Robin; Fox, Derek; Schneider, Donald P.

    2016-08-01

    Differentiating between active galactic nucleus (AGN) activity and star formation in z ˜ 2 galaxies is difficult because traditional methods, such as line-ratio diagnostics, change with redshift, while multi-wavelength methods (X-ray, radio, IR) are sensitive to only the brightest AGNs. We have developed a new method for spatially resolving emission lines using the Hubble Space Telescope/Wide Field Camera 3 G141 grism spectra and quantifying AGN activity through the spatial gradient of the [O iii]/Hβ line ratio. Through detailed simulations, we show that our novel line-ratio gradient approach identifies ˜40% more low-mass and obscured AGNs than obtained by classical methods. Based on our simulations, we developed a relationship that maps the stellar mass, star formation rate, and measured [O iii]/Hβ gradient to the AGN Eddington ratio. We apply our technique to previously studied stacked samples of galaxies at z ˜ 2 and find that our results are consistent with these studies. This gradient method will also be able to inform other areas of galaxy evolution science, such as inside-out quenching and metallicity gradients, and will be widely applicable to future spatially resolved James Webb Space Telescope data.

  2. The Horizon-AGN simulation: morphological diversity of galaxies promoted by AGN feedback

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Peirani, Sébastien; Pichon, Christophe; Devriendt, Julien; Gavazzi, Raphaël; Welker, Charlotte; Volonteri, Marta

    2016-09-01

    The interplay between cosmic gas accretion onto galaxies and galaxy mergers drives the observed morphological diversity of galaxies. By comparing the state-of-the-art hydrodynamical cosmological simulations Horizon-AGN and Horizon-noAGN, we unambiguously identify the critical role of Active Galactic Nuclei (AGN) in setting up the correct galaxy morphology for the massive end of the population. With AGN feedback, typical kinematic and morpho-metric properties of galaxy populations as well as the galaxy-halo mass relation are in much better agreement with observations. Only AGN feedback allows massive galaxies at the center of groups and clusters to become ellipticals, while without AGN feedback those galaxies reform discs. It is the merger-enhanced AGN activity that is able to freeze the morphological type of the post-merger remnant by durably quenching its quiescent star formation. Hence morphology is shown not to be purely driven by mass but also by the nature of cosmic accretion: at constant galaxy mass, ellipticals are galaxies that are mainly assembled through mergers, while discs are preferentially built from the in situ star formation fed by smooth cosmic gas infall.

  3. A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Assef, R.; Baloković, M.; Stern, D.; Gandhi, P.; Lamperti, I.; Alexander, D. M.; Ballantyne, D. R.; Bauer, F. E.; Berney, S.; Brandt, W. N.; Comastri, A.; Gehrels, N.; Harrison, F. A.; Lansbury, G.; Markwardt, C.; Ricci, C.; Rivers, E.; Schawinski, K.; Trakhtenbrot, B.; Treister, E.; Urry, C. Megan

    2016-07-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (N H ≃ (5-8) × 1023 cm-2 ). We find that the SC BAT and SC NuSTAR measurements are consistent, suggesting that this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGNs and found that it is much more effective than broadband ratios (e.g., 100% using SC versus 20% using 8-24 keV/3-8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the Balmer decrement corrected [O iii] to observed X-ray emission ratio ({F}[{{O}{{III}}]}/{F}2{--10 {keV}}{obs}\\gt 1) and WISE colors do not identify most of them as AGNs. Based on this small sample, we find that a higher fraction of these AGNs are in the final merger stage (<10 kpc) than typical BAT AGNs. Additionally, these nine obscured AGNs have, on average, ≈4× higher accretion rates than other BAT-detected AGNs (< {λ }{Edd}> \\=\\0.068+/- 0.023 compared to < {λ }{Edd}> \\=\\0.016+/- 0.004). The robustness of SC at identifying Compton-thick AGNs implies that a higher fraction of nearby AGNs may be Compton-thick (≈22%) and the sum of black hole growth in Compton-thick AGNs (Eddington ratio times population percentage) is nearly as large as mildly obscured and unobscured AGNs.

  4. A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Assef, R.; Baloković, M.; Stern, D.; Gandhi, P.; Lamperti, I.; Alexander, D. M.; Ballantyne, D. R.; Bauer, F. E.; Berney, S.; Brandt, W. N.; Comastri, A.; Gehrels, N.; Harrison, F. A.; Lansbury, G.; Markwardt, C.; Ricci, C.; Rivers, E.; Schawinski, K.; Trakhtenbrot, B.; Treister, E.; Urry, C. Megan

    2016-07-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (N H ≃ (5–8) × 1023 cm‑2 ). We find that the SC BAT and SC NuSTAR measurements are consistent, suggesting that this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGNs and found that it is much more effective than broadband ratios (e.g., 100% using SC versus 20% using 8–24 keV/3–8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the Balmer decrement corrected [O iii] to observed X-ray emission ratio ({F}[{{O}{{III}}]}/{F}2{--10 {keV}}{obs}\\gt 1) and WISE colors do not identify most of them as AGNs. Based on this small sample, we find that a higher fraction of these AGNs are in the final merger stage (<10 kpc) than typical BAT AGNs. Additionally, these nine obscured AGNs have, on average, ≈4× higher accretion rates than other BAT-detected AGNs (< {λ }{Edd}> \\=\\0.068+/- 0.023 compared to < {λ }{Edd}> \\=\\0.016+/- 0.004). The robustness of SC at identifying Compton-thick AGNs implies that a higher fraction of nearby AGNs may be Compton-thick (≈22%) and the sum of black hole growth in Compton-thick AGNs (Eddington ratio times population percentage) is nearly as large as mildly obscured and unobscured AGNs.

  5. VizieR Online Data Catalog: Intranight optical variability of AGN (Goyal+, 2013)

    NASA Astrophysics Data System (ADS)

    Goyal, A.; Gopal-Krishna; Wiita, P. J.; Stalin, C. S.; Sagar, R.

    2014-09-01

    Our sample of TeV blazars consists of two sets. Set 1 is derived from the list of TeV-detected extragalactic AGNs, published by Weekes (2008, AIP Conf. Ser. Vol. 1085, p. 3, table 2 of his paper). Our set 2 of TeV blazars was derived from table 1 of Abdo et al. (2010ApJ...715..429A, Cat. J/ApJ/715/429), consisting of 709 TeV-detected AGNs, which is based on 11 months of monitoring with Fermi LAT. (2 data files).

  6. The role of interactions in triggering bars, spiral arms and AGN in disk galaxies

    NASA Astrophysics Data System (ADS)

    Nair, Preethi; Ellison, Sara L.; Patton, David R.

    2016-01-01

    The role of secular structures like bars, rings and spiral arms in triggering star formation and AGN activity in disk galaxies are not well understood. In addition, the mechanisms which create and destroy these structures are not well characterized. Mergers are considered to be one of the main mechanisms which can trigger bars in massive disk galaxies. Using a sample of ~8000 close pair galaxies at 0.02 < z < 0.06 from the Sloan Digital Sky Survey, I will present results illustrating the role of mergers in triggering bars, rings, spiral arms and AGN as a function of close pair separation and merger ratios as well as their dependence on morphology and other physical properties of the galaxies. Time permitting, I will show how resolved IFU observations from SDSS MaNGA will help to place stronger constraints on the role of these structures in triggering star formation and AGN.

  7. The influence of local environment on the emergence of AGN activity in galaxies

    NASA Astrophysics Data System (ADS)

    Martínez, M. A.; Del Olmo, A.; Perea, J.; Coziol, R.; Focardi, P.

    2011-11-01

    We have carried out a spectroscopic study to determine the frequency and nature of the nuclear activity found in compact groups. With this aim we chose two samples, one selected from the Hickson Compact Groups Catalogue and another one from the Updated Zwicky Catalogue of Compact Groups. With the analysis of 1056 galaxies we found that more than 71% present some kind of emission, most of them, being low luminosity AGN (L_{Hα}=10^{39} erg s^{-1}). From these we only detect broad components in 16 which means a remarkable deficiency of broad line AGNs as compared to narrow lineAGNs, despite the high frequency of active galaxies encountered ingeneral in these groups.

  8. The Effective Eddington Limit for AGN

    NASA Astrophysics Data System (ADS)

    Vasudevan, Ranjan

    2008-10-01

    Feedback is an integral component of AGN and galaxy co-evolution. The outward radiation pressure balances the inward gravitational force on the dusty gas in the galaxy bulge at an effective Eddington limit, which is lower than the canonical Eddington limit. We have shown that absorption in AGN in The Swift/BAT 9-month survey is overwhelmingly located below the effective Eddington limit. Here we propose to observe the only three objects from this survey which are at this limit. Other sources near this boundary exhibit warm absorbers and outflows, and searching for evidence of such features in our proposed observations will provide an unprecedented level of detail in understanding sources in which the AGN is in the process of shaping the host galaxy.

  9. AGN Physics in the CTA Era

    NASA Astrophysics Data System (ADS)

    Zech, Andreas; Boisson, Catherine; Sol, Hélène

    With the start of its Preparatory Phase, a new step has been made towards the construction of CTA, the future large Cherenkov Telescope Array of ground-based gamma-ray astronomy. A two-day workshop devoted to "AGN physics in the CTA era" will be held in Toulouse, May 16th-17th 2011, in parallel to a general meeting of the CTA consortium. Combining reviews and contributed talks, the meeting will aim to present the current state of the art and to characterize future observing programmes for the various facets of AGN science at very high energies (VHE). Topics to be discussed include AGN population studies, particle acceleration and VHE emission models, variability studies, multiwavelength approach, EBL connection, VHE extended emission (radiogalaxies, pair haloes, diffuse background), passive black holes, primordial black holes ... Further information, including the full program, can be found on the conference webpage: http://cta.obspm.fr/agnworkshop2011/

  10. Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions

    NASA Astrophysics Data System (ADS)

    Marin, F.; Goosmann, R. W.; Gaskell, C. M.

    2015-05-01

    type-2 viewing angles the polarization switches to perpendicular and rises to ~50%. Conclusions: Our modeling shows that the introduction of fragmented dusty tori significantly alters the resulting net polarization of an AGN. Comparison of our models to polarization observations of large AGN samples greatly favors geometrically compact clumpy tori over extended ones.

  11. X-ray Surface Brightness Profiles of Active Galactic Nuclei in the Extended Groth Strip: Implications for AGN Feedback

    NASA Astrophysics Data System (ADS)

    Chatterjee, Suchetana; Newman, Jeffrey A.; Jeltema, Tesla; Myers, Adam D.; Aird, James; Coil, Alison L.; Cooper, Michael; Finoguenov, Alexis; Laird, Elise; Montero-Dorta, Antonio; Nandra, Kirpal; Willmer, Christopher; Yan, Renbin

    2015-08-01

    Using data from the All Wavelength Extended Groth Strip International Survey (AEGIS) we statistically detect the extended X-ray emission in the interstellar medium (ISM)/intracluster medium (ICM) in both active and normal galaxies at 0.3 <= z <= 1.3. For both active galactic nuclei (AGN) host galaxy and normal galaxy samples that are matched in restframe color, luminosity, and redshift distribution, we tentatively detect excess X-ray emission at scales of 1-10'' at a few σ significance in the surface brightness profiles. The exact significance of this detection is sensitive to the true characterization of Chandra's point-spread function. The observed excess in the surface brightness profiles is suggestive of lower extended emission in AGN hosts compared to normal galaxies. This is qualitatively similar to theoretical predictions of the X-ray surface brightness profile from AGN feedback models, where feedback from AGN is likely to evacuate the gas from the center of the galaxy/cluster. We propose that AGN that are intrinsically underluminous in X-rays, but have equivalent bolometric luminosities to our sources will be the ideal sample to study more robustly the effect of AGN feedback on diffuse ISM/ICM gas.

  12. FE Features in Highly Obscured AGN

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.

    1999-01-01

    This final report is a summary of the combined study of ASCA (Advanced Satellite for Cosmology and Astrophysics) observations of NGC 7582 with archival ROSAT HRI (High Resolution Imager) and PSPC (Position Sensitive Proportional Counter) data. These observations were important in that they established that X-ray emission in NGC 7582, the most narrow-line of NLXGs (narrow-line X-ray galaxies), is associated with an AGN (Active Galactic Nuclei). Thus implying that all NLXGs are obscured AGN, as has been hypothesized to explain the X-ray spectral background paradox.

  13. VizieR Online Data Catalog: Eddington ratios of faint AGN (Gavignaud+, 2008)

    NASA Astrophysics Data System (ADS)

    Gavignaud, I.; Wisotzki, L.; Bongiorno, A.; Paltani, S.; Zamorani, G.; Moller, P.; Le Brun, V.; Husemann, B.; Lamareille, F.; Schramm, M.; Le Fevre, O.; Bottini, D.; Garilli, B.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; Arnaboldi, M.; Arnouts, S.; Bardelli, S.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Guzzo, L.; Ilbert, O.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pello, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Bondi, M.; Busarello, G.; Cucciati, O.; de La Torre, S.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.; Vergani, D.

    2009-01-01

    We use one of the deepest spectroscopic samples of broad-line active galactic nuclei (AGN) currently available, extracted from the VIMOS VLT Deep Survey (VVDS, Cat. ), to compute the MgII and CIV virial-mass estimates of 120 super-massive black holes in the redshift range 1.0

  14. VizieR Online Data Catalog: Revisited jet bending in γ-ray AGNs (Graham+, 2014)

    NASA Astrophysics Data System (ADS)

    Graham, P. J.; Tingay, S. J.

    2016-08-01

    We use the "clean sample", a subset of sources from the second Fermi Large Area Telescope (LAT) Active Galactic Nuclei (AGN) catalog (2LAC; Ackermann et al. 2011, cat. J/ApJ/743/171) that possess high-confidence associations between radio and γ-ray counterparts, and Very Long Baseline Interferometry (VLBI) images accessible in the published literature or from the Radio Fundamental Catalog (RFC; version "rfc_2013d"; Beasley et al. 2002 (cat. J/ApJS/141/13), Fomalont et al. 2003 (cat. J/AJ/126/2562), Immer et al. 2011 (cat. J/ApJS/194/25), Kovalev et al. 2007 (cat. J/AJ/133/1236), Petrov et al. (2005, cat. J/AJ/129/1163; 2006, cat. J/AJ/131/1872; 2008, cat. J/AJ/136/580; 2011, cat. J/AJ/142/35; 2011, cat. J/MNRAS/414/2528), Petrov & Taylor 2011 (cat. J/AJ/142/89), Petrov (2011, cat. J/AJ/142/105; 2012, cat. J/MNRAS/419/1097; 2013, cat. J/AJ/146/5)). Our RFC-based sample consists of 351 AGNs in total. The sample contains 151 γ-ray-loud AGNs from the clean sample (see Table1). A γ-ray-quiet subsample was defined by the 200 AGNs not detected by LAT (see Table2). (2 data files).

  15. AGNfitter: An MCMC Approach to Fitting SEDs of AGN and galaxies

    NASA Astrophysics Data System (ADS)

    Calistro Rivera, Gabriela; Lusso, Elisabeta; Hennawi, Joseph; Hogg, David W.

    2016-08-01

    I will present AGNfitter: a tool to robustly disentangle the physical processes responsible for the emission of active galactic nuclei (AGN). AGNfitter is the first open-source algorithm based on a Markov Chain Monte Carlo method to fit the spectral energy distributions of AGN from the sub-mm to the UV. The code makes use of a large library of theoretical, empirical, and semi-empirical models to characterize both the host galaxy and the nuclear emission simultaneously. The model consists in four physical components comprising stellar populations, cold dust distributions in star forming regions, accretion disk, and hot dust torus emissions. AGNfitter is well suited to infer numerous parameters that rule the physics of AGN with a proper handling of their confidence levels through the sampling and assumptions-free calculation of their posterior probability distributions. The resulting parameters are, among many others, accretion disk luminosities, dust attenuation for both galaxy and accretion disk, stellar masses and star formation rates. We describe the relevance of this fitting machinery, the technicalities of the code, and show its capabilities in the context of unobscured and obscured AGN. The analyzed data comprehend a sample of 714 X-ray selected AGN of the XMM-COSMOS survey, spectroscopically classified as Type1 and Type2 sources by their optical emission lines. The inference of variate independent obscuration parameters allows AGNfitter to find a classification strategy with great agreement with the spectroscopical classification for ˜ 86% and ˜ 70% for the Type1 and Type2 AGNs respectively. The variety and large number of physical properties inferred by AGNfitter has the potential of contributing to a wide scope of science-cases related to both active and quiescent galaxies studies.

  16. On the Star Formation-AGN Connection at zeta (is) approximately greater than 0.3

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, Andrew; Urry, C. Megan

    2013-01-01

    Using the spectra of a sample of approximately 28,000 nearby obscured active galaxies from Data Release 7 of the Sloan Digital Sky Survey (SDSS), we probe the connection between active galactic nucleus (AGN) activity and star formation over a range of radial scales in the host galaxy. We use the extinction-corrected luminosity of the [O iii] 5007A line as a proxy of intrinsic AGN power and supermassive black hole (SMBH) accretion rate. The star formation rates (SFRs) are taken from the MPA-JHU value-added catalog and are measured through the 3 inch SDSS aperture. We construct matched samples of galaxies covering a range in redshifts. With increasing redshift, the projected aperture size encompasses increasing amounts of the host galaxy. This allows us to trace the radial distribution of star formation as a function of AGN luminosity. We find that the star formation becomes more centrally concentrated with increasing AGN luminosity and Eddington ratio. This implies that such circumnuclear star formation is associated with AGN activity, and that it increasingly dominates over omnipresent disk star formation at higher AGN luminosities, placing critical constraints on theoretical models that link host galaxy star formation and SMBH fueling. We parameterize this relationship and find that the star formation on radial scales (is) less than 1.7 kpc, when including a constant disk component, has a sub-linear dependence on SMBH accretion rate: SFR in proportion to solar mass(sup 0.36), suggesting that angular momentum transfer through the disk limits accretion efficiency rather than the supply from stellar mass loss.

  17. X-Ray Absorbed, Broad-Lined, Red AGN and the Cosmic X-Ray Background

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Wilkes, Belinda

    2005-01-01

    We have obtained XMM spectra for five red, 2MASS AGN, selected from a sample observed by Chandra to be X-ray bright and to cover a range of hardness ratios. Our results confirm the presence of substantial absorbing material in three sources which have optical classifications ranging from Type 1 to Type 2, with an intrinsically flat (hard) power law continuum indicated in the other two. The presence of both X-ray absorption and broad optical emission lines with the usual strength suggests either a small (nuclear) absorber or a favored viewing angle so as to cover the X-ray source but not the broad emission line region (BELR). A soft excess is detected in all three Type 1 sources. We speculate that this soft X-ray emission may arise in an extended region of ionized gas, perhaps linked with the polarized (scattered) light which is a feature of these sources. The spectral complexity revealed by XMM emphasizes the limitations of the low S/N Chandra data. Overall, the new XMM results strengthen our conclusions (Wilkes et al. 2002) that the observed X-ray continua of red AGN are unusually hard at energies greater than 2 keV. Whether due to substantial line-of-sight absorption or to an intrinsically hard or reflection-dominated spectrum, these 'red' AGN have an observed spectral form consistent with contributing significantly to the missing had absorbed population of the Cosmic X-ray Background (CXRB). When absorption and or reflection is taken into account, all these AGN have power law slopes typical of broad-line (Type 1) AGN (Gamma approximately 1.9). This appears to resolve the spectral paradox which for so long has existed between the CXRB and the AGN thought to be the dominant contributors. It also suggests two scenarios whereby Type 1 AGN/QSOs may be responsible for a significant fraction of the CXRB at energies above 2 keV: 1) X-ray absorbed AGN/QSOs with visible broad emission lines; 2) AGN/QSOs with complex spectra whose hardness greater than 2 keV is not

  18. Narrow-line region gas kinematics of 24 264 optically selected AGN: the radio connection

    NASA Astrophysics Data System (ADS)

    Mullaney, J. R.; Alexander, D. M.; Fine, S.; Goulding, A. D.; Harrison, C. M.; Hickox, R. C.

    2013-07-01

    Using a sample of 24 264 optically selected active galactic nuclei (AGNs) from the SDSS DR7 data base, we characterize how the profile of the [O III] λ5007 emission line relates to bolometric luminosity (LAGN), Eddington ratio, radio loudness, radio luminosity (L1.4 GHz) and optical class (i.e. broad/narrow-line Seyfert 1, type 2) to determine what drives the kinematics of this kpc-scale line emitting gas. First, we use spectral stacking to characterize how the average [O III] λ5007 profile changes as a function of these five variables. After accounting for the known correlation between LAGN and L1.4 GHz, we report that L1.4 GHz has the strongest influence on the [O III] λ5007 profile, with AGNs of moderate radio luminosity (L1.4 GHz = 1023-1025 W Hz-1) having the broadest [O III] λ5007 profiles. Conversely, we find only a modest change in the [O III] λ5007 profile with increasing radio loudness and find no significant difference between the [O III] λ5007 profiles of broad- and narrow-line Seyfert 1s. When binned according to Eddington ratio, only the AGNs in our highest bin (i.e. >0.3) show any signs of having broadened [O III] λ5007 profiles, although the small numbers of such extreme AGNs in our sample mean we cannot rule out that other processes (e.g. radio jets) are responsible for this broadening. The [O III] λ5007 profiles of type 1 and type 2 AGNs show the same trends in terms of line width, but type 1 AGNs display a much stronger `blue wing', which we interpret as evidence of outflowing ionized gas. We perform multicomponent fitting to the Hβ, [O III] λλ4959, 5007, [N II] λλ6548, 6584 and Hα lines for all the AGNs in our sample to calculate the proportions of AGNs with broad [O III] λ5007 profiles. The individual fits confirm the results from our stacked spectra; AGNs with L1.4 GHz > 1023 W Hz-1 are roughly five times more likely to have extremely broad [O III] λ5007 lines (full width at half-maximum, FWHMAvg > 1000 km s-1) compared to

  19. Revisiting the relationship between 6 μm and 2-10 keV continuum luminosities of AGN

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Rovilos, E.; Hernán-Caballero, A.; Barcons, X.; Blain, A.; Caccianiga, A.; Della Ceca, R.; Severgnini, P.

    2015-05-01

    We have determined the relation between the AGN luminosities at rest-frame 6 μm associated with the dusty torus emission and at 2-10 keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 1042 and 1046 erg s-1 and redshifts from 0.05 to 2.8. The rest-frame 6 μm luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L6 μm ∝ L_{2-10 keV}^{0.99± 0.03}, with intrinsic scatter, Δ log L6 μm ˜ 0.35 dex. The L_{6 μ m}/L_{2-10 keV} luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths <12 μm and are overall ˜1.3-2 times fainter at 6 μm than type 1 AGN at a given X-ray luminosity. Regardless of whether type 1 and type 2 AGN have the same or different nuclear dusty toroidal structures, our results imply that the AGN emission at rest-frame 6 μm is not isotropic due to self-absorption in the dusty torus, as predicted by AGN torus models. Thus, AGN surveys at rest-frame ˜6 μm are subject to modest dust obscuration biases.

  20. THE BULK OF THE BLACK HOLE GROWTH SINCE z {approx} 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER-AGN CONNECTION

    SciTech Connect

    Cisternas, Mauricio; Jahnke, Knud; Inskip, Katherine J.; Robaina, Aday R.; Andrae, Rene; Kartaltepe, Jeyhan; Koekemoer, Anton M.; Lisker, Thorsten; Scodeggio, Marco; Sheth, Kartik; Capak, Peter; Trump, Jonathan R.; Impey, Chris D.; Miyaji, Takamitsu; Lusso, Elisabeta; Brusa, Marcella; Cappelluti, Nico; Civano, Francesca; Ilbert, Olivier; Leauthaud, Alexie

    2011-01-10

    What is the relevance of major mergers and interactions as triggering mechanisms for active galactic nuclei (AGNs) activity? To answer this long-standing question, we analyze 140 XMM-Newton-selected AGN host galaxies and a matched control sample of 1264 inactive galaxies over z {approx} 0.3-1.0 and M{sub *} < 10{sup 11.7} M{sub sun} with high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging from the COSMOS field. The visual analysis of their morphologies by 10 independent human classifiers yields a measure of the fraction of distorted morphologies in the AGN and control samples, i.e., quantifying the signature of recent mergers which might potentially be responsible for fueling/triggering the AGN. We find that (1) the vast majority (>85%) of the AGN host galaxies do not show strong distortions and (2) there is no significant difference in the distortion fractions between active and inactive galaxies. Our findings provide the best direct evidence that, since z {approx} 1, the bulk of black hole (BH) accretion has not been triggered by major galaxy mergers, therefore arguing that the alternative mechanisms, i.e., internal secular processes and minor interactions, are the leading triggers for the episodes of major BH growth. We also exclude an alternative interpretation of our results: a substantial time lag between merging and the observability of the AGN phase could wash out the most significant merging signatures, explaining the lack of enhancement of strong distortions on the AGN hosts. We show that this alternative scenario is unlikely due to (1) recent major mergers being ruled out for the majority of sources due to the high fraction of disk-hosted AGNs, (2) the lack of a significant X-ray signal in merging inactive galaxies as a signature of a potential buried AGN, and (3) the low levels of soft X-ray obscuration for AGNs hosted by interacting galaxies, in contrast to model predictions.

  1. Correlaciones cruzadas quasar-galaxia y AGN-galaxia

    NASA Astrophysics Data System (ADS)

    Martínez, H. J.; Merchán, M. E.; Valotto, C. A.; García Lambas, D.

    We compute quasar-galaxy and AGN-galaxy cross-correlation functions for samples taken from the Véron-Cetty & Véron (1998) catalog of quasars and active galaxies, using tracer galaxies taken from the Edinburgh/Durham Southern Catalog. The sample of active galaxy targets shows positive correlation at projected separations rp < 6 h-1 ~Mpc consistent with the usual power-law. On the other hand, we do not find a statistically significant positive quasar-galaxy correlation signal except in the range 3 h-1 Mpc < rp < 6 h-1 Mpc where we find similar AGN-galaxy and quasar-galaxy correlation amplitudes. At separations rp<3~h-1 ~Mpc a strong decline of quasar-galaxy correlations is observed, suggesting a significant local influence of quasars in galaxy formation. In an attempt to reproduce the observed cross-correlation between quasars and galaxies, we have performed CDM cosmological hydrodynamical simulations and tested the viability of a scenario based on the model developed by Silk & Rees (1998). In this scheme a fraction of the energy released by quasars is considered to be transferred into the baryonic component of the intergalactic medium in the form of winds. The results of the simulations suggest that the shape of the observed quasar-galaxy cross-correlation function could be understood in a scenario where a substantial amount of energy is transferred to the medium at the redshift of maximum quasar activity.

  2. THE LICK AGN MONITORING PROJECT: PHOTOMETRIC LIGHT CURVES AND OPTICAL VARIABILITY CHARACTERISTICS

    SciTech Connect

    Walsh, Jonelle L.; Bentz, Misty C.; Barth, Aaron J.; Minezaki, Takeo; Sakata, Yu; Yoshii, Yuzuru; Baliber, Nairn; Bennert, Vardha Nicola; Street, Rachel A.; Treu, Tommaso; Li Weidong; Filippenko, Alexei V.; Stern, Daniel; Brown, Timothy M.; Canalizo, Gabriela; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak

    2009-11-01

    The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10{sup 6}-10{sup 7} M {sub sun}, as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.

  3. MOJAVE: XIII. Parsec-scale AGN Jet Kinematics Analysis Based on 19 years of VLBA Observations at 15 GHz

    NASA Astrophysics Data System (ADS)

    Lister, M. L.; Aller, M. F.; Aller, H. D.; Homan, D. C.; Kellermann, K. I.; Kovalev, Y. Y.; Pushkarev, A. B.; Richards, J. L.; Ros, E.; Savolainen, T.

    2016-07-01

    We present 1625 new 15 GHz (2 cm) VLBA images of 295 jets associated with active galactic nuclei (AGNs) from the MOJAVE and 2 cm VLBA surveys, spanning observations between 1994 August 31 and 2013 August 20. For 274 AGNs with at least 5 VLBA epochs, we have analyzed the kinematics of 961 individual bright features in their parsec-scale jets. A total of 122 of these jets have not been previously analyzed by the MOJAVE program. In the case of 451 jet features that had at least 10 epochs, we also examined their kinematics for possible accelerations. At least half of the well-sampled features have non-radial and/or accelerating trajectories, indicating that non-ballistic motion is common in AGN jets. Since it is impossible to extrapolate any accelerations that occurred before our monitoring period, we could only determine reliable ejection dates for ˜ 24 % of those features that had significant proper motions. The distribution of maximum apparent jet speeds in all 295 AGNs measured by our program to date is peaked below 5c, with very few jets with apparent speeds above 30c. The fastest speed in our survey is ˜ 50c, measured in the jet of the quasar PKS 0805-07, and is indicative of a maximum jet Lorentz factor of ˜50 in the parent population. An envelope in the maximum jet speed versus redshift distribution of our sample provides additional evidence of this upper limit to the speeds of radio-emitting regions in parsec-scale AGN jets. The Fermi-LAT-detected gamma-ray AGNs in our sample have, on average, higher jet speeds than non-LAT-detected AGNs, indicating a strong correlation between parsec-scale jet speed and the gamma-ray Doppler boosting factor. We have identified 11 moderate-redshift (z\\lt 0.35) AGNs with fast apparent speeds (\\gt 10c) that are strong candidates for future TeV gamma-ray detection. Of the five gamma-ray loud narrow-lined Seyfert I AGNs in our sample, three show highly superluminal jet motions, while the others have sub-luminal speeds. This

  4. Physics of Gamma Ray Emitting AGN

    NASA Astrophysics Data System (ADS)

    Ojha, Roopesh; Lovell, Jim; Edwards, Philip; Kadler, Matthias; Monitoringteam, Gamma Ray Blazar

    2011-10-01

    TANAMI is a highly productive LBA program addressing fundamental questions about AGN with VLBI observations. As the only dual-frequency VLBI monitoring program covering the southern third of the sky while Fermi is observing, TANAMI, with its associated optical/UV and X-ray components, is indispensable. For many of the most interesting sources in the sky, TANAMI provides the sole means of tracking parsec-scale jet components and associating their ejection epochs with gamma-ray flares. Further, multi-year VLBI observations are the only way to establish jet parameters, such as speeds and Doppler factors, which are essential to the study of AGN physics. We request the continuation of this program that was granted Large Proposal status from October 2009. Further observations are necessary for the multiwavelength correlation, morphological and kinematic studies for which we have set up an excellent baseline and produced interesting results e.g. shown the necessity for multi-zone models for gamma-ray production in AGN. Simultaneous observations across the electromagnetic spectrum hold the key to answering many riddles posed by AGN and the next 5-10 years when Fermi is observing provide a window of opportunity that TANAMI is exploiting.

  5. A Global Picture of AGN Winds

    NASA Technical Reports Server (NTRS)

    Kazanas, D.; Fukumura, K.

    2011-01-01

    We present a unified structure for accretion powered sources across their entire luminosity range from accreting galactic black holes to the most luminous quasars, with emphasis on AGN and their phenomenology. Central to this end is the notion of MHD winds launched from the accretion disks that power these objects. This work similar in spirit to that of Elvis of more that a decade ago, provides, on one hand, only the broadest characteristics of these objects, but on the other, also scaling laws that allow one to make contact with objects of different luminosity. The conclusion of this work is that AGN phenomenology can be accounted for in terms of dot(m), the wind mass flux in units of the Eddington value, the observer's inclination angle theta and alpha_OX the logarithmic slope between UV and X-ray flares. However given the well known correlation between alpha(sub ox) and UV Luminosity, we conclude that the AGN structure depends on only two parameters. The small number of model parameters hence suggests that an understanding of the global AGN properties maybe within reach.

  6. Mabel Agnes Elliott, We Hardly Knew You

    ERIC Educational Resources Information Center

    McGonigal, Kathryn; Galliher, John F.

    2008-01-01

    Sociologist Mabel Agnes Elliott was elected the fourth president of the Society for the Study of Social Problems in 1956-1957 and was the first woman to hold this position. She was an anti-war activist, a feminist and a creative and diligent writer. Yet she experienced many challenges. The Federal Bureau of Investigation kept an active file on…

  7. AGN identification and host galaxies properties in the MOSDEF survey

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Coil, Alison L.; MOSDEF Team

    2016-06-01

    We present new results on the identification and host galaxy properties of X-ray, IR and optically-selected AGN at 1.4 < z < 3.8, using spectroscopic data from the on-going MOSDEF survey, which is obtaining rest-frame optical spectra of ~1,500 galaxies and AGN using the new Keck/MOSFIRE instrument. We find clear selection effects when identifying AGN at different wavelengths, in that optically-selected AGN are more likely to be found in galaxies with low SFR, while IR AGN are typically found in galaxies with higher SFR. There is also a bias against finding AGN at any wavelength in low mass galaxies. We find that optical AGN selection identifies less powerful AGN that may be obscured at other wavelengths. Combining the AGN we identify at different wavelengths, we find that AGN host galaxies have similar stellar age and dust content as inactive galaxies of the same stellar mass. Finally, we do not find a significant correlation between either SFR or stellar mass and L[OIII], which argues against the presence of strong AGN feedback.

  8. The Horizon-AGN Simulation: Morphological Diversity of Galaxies ,Promoted by AGN Feedback

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Peirani, Sébastien; Pichon, Christophe; Devriendt, Julien; Gavazzi, Raphaël; Welker, Charlotte; Volonteri, Marta

    2016-09-01

    The interplay between cosmic gas accretion onto galaxies and galaxy mergers drives the observed morphological diversity of galaxies. By comparing the state-of-the-art hydrodynamical cosmological simulations HORIZON-AGN and HORIZON-NOAGN, we unambiguously identify the critical role of Active Galactic Nuclei (AGN) in setting up the correct galaxy morphology for the massive end of the population. With AGN feedback, typical kinematic and morpho-metric properties of galaxy populations as well as the galaxy-halo mass relation are in much better agreement with observations. Only AGN feedback allows massive galaxies at the center of groups and clusters to become ellipticals, while without AGN feedback those galaxies reform discs. It is the merger-enhanced AGN activity that is able to freeze the morphological type of the post-merger remnant by durably quenching its quiescent star formation. Hence morphology is shown not to be purely driven by mass but also by the nature of cosmic accretion: at constant galaxy mass, ellipticals are galaxies that are mainly assembled through mergers, while discs are preferentially built from the in situ star formation fed by smooth cosmic gas infall.

  9. What are the galaxies that host MIR-selected AGN?

    NASA Astrophysics Data System (ADS)

    Rosario, David

    2016-08-01

    Infra-red selection techniques, sensitive to dust strongly heated by an AGN, offer a way to identify some of the most obscured accretion events in the Universe. I will describe the results of a comprehensive multi-wavelength study of AGN to z>2 selected using Spitzer/IRAC based methods in the COSMOS field. Armed with AGN-optimised redshifts and stellar masses, we explore the dust emission from the active nucleus and the host galaxy. We demonstrate that IR-selected AGN tend to be found in low mass host galaxies, when compared to other AGN identification methods. The star-formation rates of obscured and unobscured IR-selected AGN are very similar, implying that large-scale obscuration with co-eval star-bursts are not found in a major proportion of heavily obscured AGN.

  10. Detection of faint broad emission lines in type 2 AGN: I. Near infrared observations and spectral fitting

    NASA Astrophysics Data System (ADS)

    Onori, F.; La Franca, F.; Ricci, F.; Brusa, M.; Sani, E.; Maiolino, R.; Bianchi, S.; Bongiorno, A.; Fiore, F.; Marconi, A.; Vignali, C.

    2016-09-01

    We present medium resolution near infrared spectroscopic observations of 41 obscured and intermediate class AGN (type 2, 1.9 and 1.8; AGN2) with redshift z ≲0.1, selected from the Swift/BAT 70-month catalogue. The observations have been carried out in the framework of a systematic study of the AGN2 near infrared spectral properties and have been executed using ISAAC/VLT, X-shooter/VLT and LUCI/LBT, reaching an average S/N ratio of ˜30 per resolution element. For those objects observed with X-shooter we also obtained simultaneous optical and UV spectroscopy. We have identified a component from the broad line region in 13 out of 41 AGN2, with FWHM >800 km s-1. We have verified that the detection of the broad line region components does not significantly depend on selection effects due to the quality of the spectra, the X-ray or near infrared fluxes, the orientation angle of the host galaxy or the hydrogen column density measured in the X-ray band. The average broad line region components found in AGN2 has a significantly (a factor 2) smaller FWHM if compared with a control sample of type 1 AGN.

  11. Empirical links between XRB and AGN accretion using the complete z < 0.4 spectroscopic CSC/SDSS catalog

    SciTech Connect

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Sobolewska, Malgosia; Kim, Dong-Woo; Constantin, Anca; Kalfountzou, Eleni; Hyde, Ashley K.; Zhou, Hongyan; Haggard, Daryl; Kelly, Brandon C.

    2013-12-01

    Striking similarities have been seen between accretion signatures of Galactic X-ray binary (XRB) systems and active galactic nuclei (AGNs). XRB spectral states show a V-shaped correlation between X-ray spectral hardness and Eddington ratio as they vary, and some AGN samples reveal a similar trend, implying analogous processes at vastly larger masses and timescales. To further investigate the analogies, we have matched 617 sources from the Chandra Source Catalog to Sloan Digital Sky Survey spectroscopy, and uniformly measured both X-ray and optical spectral characteristics across a broad range of AGN and galaxy types. We provide useful tabulations of X-ray spectral slope for broad- and narrow-line AGNs, star-forming and passive galaxies, and composite systems, also updating relationships between optical (Hα and [O III]) line emission and X-ray luminosity. We further fit broadband spectral energy distributions with a variety of templates to estimate bolometric luminosity. Our results confirm a significant trend in AGNs between X-ray spectral hardness and Eddington ratio expressed in X-ray luminosity, albeit with significant dispersion. The trend is not significant when expressed in the full bolometric or template-estimated AGN luminosity. We also confirm a relationship between the X-ray/optical spectral slope α{sub ox} and Eddington ratio, but it may not follow the trend predicted by analogy with XRB accretion states.

  12. AGN populations in GOODS-N through eMERGE ultra-deep JVLA observations

    NASA Astrophysics Data System (ADS)

    Guidetti, Daria; Bondi, M.; Prandoni, I.; Beswick, R. J.; Muxlow, T. W. B.; Wrigley, N.; Smail, I. R.; McHardy, I.; Ivison, R.; eMERGE Collaboration

    2016-08-01

    Multi-wavelength studies of deep radio fields show a composite population of star-forming galaxies, radio-quiet and radio-loud AGNs, with the formers dominating at the lowest flux densities (< 100 microJy). However, the exact mixture between these types of radio sources is still matter of debate. The most direct way to identify faint AGN-driven radio emission is the detection of embedded radio cores in the host galaxies, through ultra-deep and very high resolution radio observations. This would open the perspective of studying the whole AGN population in the radio band, including the radio-quiet component traditionally selected at other wavelengths (opt/IR/X-ray). Assessing the faint AGN component in deep radio fields, will provide an important tool to understand the role of nuclear activity in distant galaxies and its possible co-evolution with star-formation processes, as radio wavelengths are not affected by dust extinction and/or gas absorption. In my talk I will report about the e-MERLIN Galaxy Evolution Survey (eMERGE, PI: Muxlow), a legacy project which aims at undertaking a spatially-resolved study of AGN and star formation processes up to high redshift in a 30 arcmin diameter field in the GOODS-N region, through ultra-deep (sub-microJy rms), sub-arcsec (50-500 mas) imaging at 1.4 and 5 GHz, using combined JVLA and eMERLIN observations. I will focus on the 5 GHz JVLA mosaic observations and catalogue of GOODS-N (94 sources), in the framework of the eMERGE project, and on the study of a larger sample of GOODS-N galaxies (300 objects) selected at 1.4 GHz to constrain the presence of AGN cores in moderate-to-high redshift (1

  13. Multi-wavelength properties and SMBH's masses of the isolated AGNs in the Local Universe

    NASA Astrophysics Data System (ADS)

    Vavilova, I. B.; Vasylenko, A. A.; Babyk, Iu. V.; Pulatova, N. G.

    2016-08-01

    The sample of 36 nearest isolated AGNs was cross-matched by 2MIG and Veron-Cetty catalogues and limited to Ks ≤ 12.0m and Vr < 15 000 km/s in the northern sky (δ ≥ -15°). These objects were in isolation during ~ 3 Gyrs. For revealing their multi-wavelength properties we used all the available databases obtained with ground-based and space observatories (from radio to X-ray ranges). It is allowed us to separate the internal evolution mechanisms from the environment influence and consider them as two separate processes related to fueling nuclear activity and accretion on the SMBHs outside of the environment. In this report we present briefly main results, which were already published (Pulatova N., Vavilova I., Sawangwit U. et al. The 2MIG isolated AGNs - I. General and multiwavelength properties of AGNs and host galaxies in the northern sky, MNRAS, 447, Issue 3, p. 2209-2223 (2015)). We accentuate that for the first time we revealed that the host isolated galaxies with AGNs of Sy1 type (without faint companions) appear to possess the bar morphological features (e.g., the interaction with neighboring galaxies is not necessary condition for broad-line region formation). We give also current results as concerns with more detail X-ray analysis, emission features and spectral models for several AGNs for which a cumulative soft and hard energy spectrum was reconstructed. The estimates of SMBH masses show that are systematically lower than the SMBH masses of AGNs located in a dense environment.

  14. Exploring the Connection Between Star Formation and AGN Activity in the Local Universe

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman. T. M.; Ptak, Andrew; Schiminovich, D.; O'Dowd, M.; Bertincourt, B.

    2012-01-01

    We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic con- tributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 micron emission-line is well correlated with the star formation rate (SFR) measured from the SDSS spectra, and this holds for the star forming, composite, and AGN-dominated systems. AGN show a clear excess of [NeIII] 15.6 micron emission relative to star forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including: the mid-IR spectral slope, the ratio of the [NeV] 14.3 micron to [NeII] micron 12.8 fluxes, the equivalent widths of the 7.7, 11.3, and 17 micron PAH features, and the optical "D" parameter which measures the distance a source lies from the locus of star forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN-dominance. We find that the PAH 11.3 micron feature is significantly suppressed in the most AGN-dominated systems.

  15. A POWERFUL AGN OUTBURST IN RBS 797

    SciTech Connect

    Cavagnolo, K. W.; McNamara, B. R.; Wise, M. W.; Nulsen, P. E. J.; Gitti, M.; Brueggen, M.; Rafferty, D. A.

    2011-05-10

    Utilizing {approx}50 ks of Chandra X-Ray Observatory imaging, we present an analysis of the intracluster medium (ICM) and cavity system in the galaxy cluster RBS 797. In addition to the two previously known cavities in the cluster core, the new and deeper X-ray image has revealed additional structure associated with the active galactic nucleus (AGN). The surface brightness decrements of the two cavities are unusually large and are consistent with elongated cavities lying close to our line of sight. We estimate a total AGN outburst energy and mean jet power of {approx}(3-6) x 10{sup 60} erg and {approx}(3-6) x 10{sup 45} erg s{sup -1}, respectively, depending on the assumed geometrical configuration of the cavities. Thus, RBS 797 is apparently among the most powerful AGN outbursts known in a cluster. The average mass accretion rate needed to power the AGN by accretion alone is {approx}1 M{sub sun} yr{sup -1}. We show that accretion of cold gas onto the AGN at this level is plausible, but that Bondi accretion of the hot atmosphere is probably not. The brightest cluster galaxy (BCG) harbors an unresolved, non-thermal nuclear X-ray source with a bolometric luminosity of {approx}2 x 10{sup 44} erg s{sup -1}. The nuclear emission is probably associated with a rapidly accreting, radiatively inefficient accretion flow. We present tentative evidence that star formation in the BCG is being triggered by the radio jets and suggest that the cavities may be driving weak shocks (M {approx} 1.5) into the ICM, similar to the process in the galaxy cluster MS 0735.6+7421.

  16. The 5-10 keV AGN luminosity function at 0.01 < z < 4.0

    NASA Astrophysics Data System (ADS)

    Fotopoulou, S.; Buchner, J.; Georgantopoulos, I.; Hasinger, G.; Salvato, M.; Georgakakis, A.; Cappelluti, N.; Ranalli, P.; Hsu, L. T.; Brusa, M.; Comastri, A.; Miyaji, T.; Nandra, K.; Aird, J.; Paltani, S.

    2016-03-01

    The active galactic nuclei (AGN) X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the AGN population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH ~ 1023 cm-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01 < z < 4.0, 41 < log Lx < 46) is 98% redshift complete with 68% spectroscopic redshifts. For sources lacking a spectroscopic redshift estimation we use the probability distribution function of photometric redshift estimation specifically tuned for AGN, and a flat probability distribution function for sources with no redshift information. We use Bayesian analysis to select the best parametric model from simple pure luminosity and pure density evolution to more complicated luminosity and density evolution and luminosity-dependent density evolution (LDDE). We estimate the model parameters that describe best our dataset separately for each survey and for the combined sample. We show that, according to Bayesian model selection, the preferred model for our dataset is the LDDE. Our estimation of the AGN luminosity function does not require any assumption on the AGN absorption and is in good agreement with previous works in the 2-10 keV energy band based on X-ray hardness ratios to model the absorption in AGN up to redshift three

  17. An alma survey of submillimeter galaxies in the extended Chandra deep field-south: The agn fraction and X-ray properties of submillimeter galaxies

    SciTech Connect

    Wang, S. X.; Brandt, W. N.; Luo, B.; Smail, I.; Alexander, D. M.; Danielson, A. L. R.; Karim, A.; Simpson, J. M.; Swinbank, A. M.; Hodge, J. A.; Walter, F.; Lehmer, B. D.; Wardlow, J. L.; Xue, Y. Q.; Chapman, S. C.; Coppin, K. E. K.; Dannerbauer, H.; De Breuck, C.; Menten, K. M.; Van der Werf, P. E-mail: niel@astro.psu.edu

    2013-12-01

    The large gas and dust reservoirs of submillimeter galaxies (SMGs) could potentially provide ample fuel to trigger an active galactic nucleus (AGN), but previous studies of the AGN fraction in SMGs have been controversial largely due to the inhomogeneity and limited angular resolution of the available submillimeter surveys. Here we set improved constraints on the AGN fraction and X-ray properties of the SMGs with Atacama Large Millimeter/submillimeter Array (ALMA) and Chandra observations in the Extended Chandra Deep Field-South (E-CDF-S). This study is the first among similar works to have unambiguously identified the X-ray counterparts of SMGs; this is accomplished using the fully submillimeter-identified, statistically reliable SMG catalog with 99 SMGs from the ALMA LABOCA E-CDF-S Submillimeter Survey. We found 10 X-ray sources associated with SMGs (median redshift z = 2.3), of which eight were identified as AGNs using several techniques that enable cross-checking. The other two X-ray detected SMGs have levels of X-ray emission that can be plausibly explained by their star formation activity. Six of the eight SMG-AGNs are moderately/highly absorbed, with N {sub H} > 10{sup 23} cm{sup –2}. An analysis of the AGN fraction, taking into account the spatial variation of X-ray sensitivity, yields an AGN fraction of 17{sub −6}{sup +16}% for AGNs with rest-frame 0.5-8 keV absorption-corrected luminosity ≥7.8 × 10{sup 42} erg s{sup –1}; we provide estimated AGN fractions as a function of X-ray flux and luminosity. ALMA's high angular resolution also enables direct X-ray stacking at the precise positions of SMGs for the first time, and we found four potential SMG-AGNs in our stacking sample.

  18. Exposing high-z obscured AGNs in the deepest IR/X-rays surveys

    NASA Astrophysics Data System (ADS)

    Daddi, Emanuele

    2012-01-01

    The identification and study of the elusive population of high redshift obscured AGNs is an important step towards understanding the fundamental phase of black hole growth in the young universe. Here we propose NIR spectroscopy with MOIRCS to confirm and characterize candidate high-z obscured/Compton-thick AGNs found in the deepest Herschel and X-ray surveys. The sample, designed to cover a range of redshifts (1.5 < z < 4), is selected from the GOODS field by use of Herschel+Spitzer (MIR to FIR colors and the presence of power-law MIR emission) and X-ray spectral properties from XMM and Chandra. The MOIRCS data are crucial to fully confirm and exploit our sample. The specific science goals include (a) obtaining independent AGN classifications and luminosities via rest-frame optical spectroscopy; (b) testing for the expected strong outflows in these high bolometric luminosity QSOs; (c) spectroscopically confirming redshifts of objects which currently have only z_phot. In the larger picture, this study will put stronger constraints on the number density of Compton-thick AGNs and on the evolution of supermassive black holes and their host galaxies.

  19. VizieR Online Data Catalog: Variability-selected AGN in Chandra DFS (Trevese+, 2008)

    NASA Astrophysics Data System (ADS)

    Trevese, D.; Boutsia, K.; Vagnetti, F.; Cappellaro, E.; Puccetti, S.

    2008-11-01

    Variability is a property shared by virtually all active galactic nuclei (AGNs), and was adopted as a criterion for their selection using data from multi epoch surveys. Low Luminosity AGNs (LLAGNs) are contaminated by the light of their host galaxies, and cannot therefore be detected by the usual colour techniques. For this reason, their evolution in cosmic time is poorly known. Consistency with the evolution derived from X-ray detected samples has not been clearly established so far, also because the low luminosity population consists of a mixture of different object types. LLAGNs can be detected by the nuclear optical variability of extended objects. Several variability surveys have been, or are being, conducted for the detection of supernovae (SNe). We propose to re-analyse these SNe data using a variability criterion optimised for AGN detection, to select a new AGN sample and study its properties. We analysed images acquired with the wide field imager at the 2.2m ESO/MPI telescope, in the framework of the STRESS supernova survey. We selected the AXAF field centred on the Chandra Deep Field South where, besides the deep X-ray survey, various optical data exist, originating in the EIS and COMBO-17 photometric surveys and the spectroscopic database of GOODS. (1 data file).

  20. Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. II. Host Galaxy Morphology and AGN Activity

    NASA Astrophysics Data System (ADS)

    Shangguan, Jinyi; Liu, Xin; Ho, Luis C.; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

    2016-05-01

    Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W (U-band) and F105W (Y-band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope. Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U - Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers. Based, in part, on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program number GO 12363.

  1. Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. II. Host Galaxy Morphology and AGN Activity

    NASA Astrophysics Data System (ADS)

    Shangguan, Jinyi; Liu, Xin; Ho, Luis C.; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

    2016-05-01

    Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W (U-band) and F105W (Y-band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope. Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U ‑ Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers. Based, in part, on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program number GO 12363.

  2. AGN flickering on 10-100 kyr timescales

    NASA Astrophysics Data System (ADS)

    Sartori, Lia F.; Schawinski, Kevin; Kill, Bill; Maksym, Peter; Koss, Michael; Argo, Megan; Urry, Meg; Wong, Ivy; Lintott, Chris

    2016-08-01

    The study of AGN variability on timescales of 10^4-10^5 years is important in order to understand the BH - host galaxy interaction and coevolution. The discovery of "Hanny's Voorwerp" (HV), an extended emission line region associated with the nearby galaxy IC 2497, provided us with a laboratory to study AGN variability over such timescales. HV was illuminated by a strong quasar in IC 2497, but this quasar significantly shut down in the last 200 kyrs. Thanks to its recent shutdown we can now explore the host galaxy unimpeded by the presence of a quasar dominating the observations, while the Voorwerp preserves the echoes of its past activity. Recent studies on the optical properties of hard X-ray selected AGN suggest that AGN may flicker on and off hundreds or thousands times with each burst lasting ~10^5 yrs. Systems similar to IC 2497 and HV, the so-called Voorwerpjes, allow us to constrain the last stages of the AGN lifecycle. On the other hand, we recently suggested that the switch on phase may be observed in the so-called optically elusive AGN. In this talk I will review both observational evidence and results from simulation work which support this picture, and explain how optically elusive AGN and Voorwerpjes galaxies can help us to understand different phases of the AGN lifecycle. Moreover, I will discuss possible implications for AGN feedback, BH - host galaxy coevolution, and the analogy between AGN and X-ray binaries accretion physics.

  3. Serching for AGNs with VST: optical variability in the COSMOS and CDFS regions

    NASA Astrophysics Data System (ADS)

    Paolillo, M.; de Cicco, Demetra; Falocco, S.; Poulain, M.; Vst-Sudare/Voice Team

    2016-08-01

    Active Galactic Nuclei (AGN) are characterised by strong variability at all wavelengths. We exploited 3 years of VST monitoring observations of the COSMOS and CDFS regions, performed within the SUDARE/VOICE surveys, to assemble a sample of AGN candidates based on variability. Variability selection does not make strong a-priori assumptions about the properties of the sources and can thus integrate and complete samples selected by other techniques. We investigate the effectiveness and reliability of this selection method by comparing it with spectroscopic, X-ray and IR selected samples, showing that variability-selection can yield extremely pure samples, with completeness >50% with respect of X-ray and IR selections. We explore the dependence of variability from obscuration, mass and accretion rate, and predict the performance that can be expected by future monitoring surveys such as LSST.

  4. Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) for the determination of [Zn(2+)] in estuarine waters.

    PubMed

    Pearson, Holly B C; Galceran, Josep; Companys, Encarna; Braungardt, Charlotte; Worsfold, Paul; Puy, Jaume; Comber, Sean

    2016-03-17

    Zinc (Zn) has been classified as a "Specific Pollutant" under Annex VIII of the EU Water Framework Directive by two thirds of the EU member states. As a result, the UK Environmental Quality Standard (EQS) for Transitional and Coastal (TrAC) Waters has been reduced from 612 nM to 121 nM total dissolved Zn. It is widely accepted that the free metal ion ([Zn(2+)]) is the most bioavailable fraction, but there are few techniques available to determine its concentration in these waters. In this work, Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) has been applied, for the first time, to determine [Zn(2+)] in estuarine waters. The AGNES method had a mean RSD of ±18%, a (deposition time dependent) limit of detection of 0.73 nM and a [Zn(2+)] recovery of 112 ± 19% from a certified reference material (BCR-505; Estuarine Water). AGNES results for 13 estuarine samples (salinity 0.1-31.9) compared well (P = 0.02) with Competitive Ligand Exchange Cathodic Stripping Voltammetry (CLE-AdCSV) except for one sample. AGNES requires minimal sample manipulation, is unaffected by adsorption of interfering species at the electrode surface and allows direct determination of free zinc ion concentrations. Therefore AGNES results can be used in conjunction with ecotoxicological studies and speciation modelling to set and test compliance with water quality standards. PMID:26920770

  5. The host galaxies of AGN with powerful relativistic jets

    NASA Astrophysics Data System (ADS)

    Olguín-Iglesias, A.; León-Tavares, J.; Kotilainen, J. K.; Chavushyan, V.; Tornikoski, M.; Valtaoja, E.; Añorve, C.; Valdés, J.; Carrasco, L.

    2016-08-01

    We present deep Near-infrared (NIR) images of a sample of 19 intermediate-redshift (0.3AGN) with powerful relativistic jets (L1.4GHz >10^27 WHz^-1), previously classified as flat-spectrum radio quasars. We also compile host galaxy and nuclear magnitudes for blazars from literature. The combined sample (this work and compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities L1.4GHz = 10^23.7 - 10^28.3WHz^-1, allowing us to divide our sample into high-excitation (quasar-mode; HERGs) and low-excitation (radio-mode; LERGs) radio galaxies. The host galaxies of our sample are bright and seem to follow the Kormendy relation. Nuclear emission (dominated by non-thermal mechanisms) and host-galaxy magnitudes show a slightly negative weak trend for LERGs. On the other hand, the m_bulge -m_nuc relation is statistically significant for HERGs. Although it may be affected by selection effects, this correlation suggests a close coupling between the relativistic jets and their host galaxy. Our findings are consistent with the excitation state (LERG/HERG) scenario. In this view, LERGs emit the bulk of their energy in the form of radio jets, producing a strong feedback mechanism, and HERGs are affected by galaxy mergers and interactions, which provide a common supply of cold gas to feed both nuclear activity and star formation episodes.

  6. Mapping the radial structure of AGN tori

    NASA Astrophysics Data System (ADS)

    Kishimoto, M.; Hönig, S. F.; Antonucci, R.; Millour, F.; Tristram, K. R. W.; Weigelt, G.

    2011-12-01

    We present mid-IR interferometric observations of six type 1 AGNs at multiple baseline lengths ranging from 27 m to 130 m, reaching high angular resolutions up to λ/B ~ 0.02 arcsec. For two of the targets, we have simultaneous near-IR interferometric measurements as well, taken within a week. We find that all the objects are partially resolved at long baselines in these IR wavelengths. The multiple-baseline data directly probe the radial distribution of the material on sub-pc scales. We show that for our sample, which is small but spans over ~2.5 orders of magnitudes in the UV/optical luminosity L of the central engine, the radial distribution clearly and systematically changes with luminosity. The brightness distribution at a given mid-IR wavelength seems to be rather well described by a power law, which makes a simple Gaussian or ring size estimation quite inadequate. In this case, a half-light radius R1/2 can be used as a representative size. We show that the higher luminosity objects become more compact in normalized half-light radii R1/2/Rin in the mid-IR, where Rin is the dust sublimation radius empirically given by the L1/2 fit of the near-IR reverberation radii. This means that, contrary to previous studies, the physical mid-IR emission size (e.g. in pc) is not proportional to L1/2, but increases with L much more slowly. With our current datasets, we find that R1/2 ∝ L0.21 ± 0.05 at 8.5 μm, and R1/2 nearly constant at 13 μm. The derived size information also seems to correlate with the properties of the total flux spectrum, in particular the smaller R1/2/Rin objects having bluer mid-IR spectral shape. We use a power-law temperature/density gradient model as a reference, and infer that the radial surface density distribution of the heated dust grains at a radius r changes from a steep ~r-1 structure in high luminosity objects to a shallower ~r0 structure in those of lower luminosity. The inward dust temperature distribution does not seem to smoothly

  7. AGN feedback in galaxy clusters and groups

    NASA Astrophysics Data System (ADS)

    Hardcastle, Martin

    2016-07-01

    Mechanical feedback via Active Galactic Nuclei (AGN) jets in the centres of galaxy groups and clusters is a crucial ingredient in current models of galaxy formation and cluster evolution. Jet feedback is believed to regulate gas cooling and thus star formation in the most massive galaxies, but a robust physical understanding of this feedback mode is currently lacking. Athena will provide (1) the first kinematic measurements on relevant spatial scales of the hot gas in galaxy, group and cluster haloes as it absorbs the impact of AGN jets, and (2) vastly improved ability to map thermodynamic conditions on scales well-matched to the jets, lobes and gas disturbances produced by them. I will present new predictions of Athena's ability to measure the energetic impact of powerful jets based on our most recent set of numerical models.

  8. The universal spectrum of AGNs and QSOs

    NASA Technical Reports Server (NTRS)

    Kazanas, D.

    1985-01-01

    The effects of the feedback of e(+)-e(-) pair reinjection in a plasma due to photon photon absorption of its own radiation are examined. A mechanism is presented which can produce an electron distribution function that can account for the overall spectral distribution of radiation of AGNs and QSOs and the specific slopes observed in the IR to UV and 2-50 keV bands. It is interesting to note that the necessary condition for this mechanism to work (i.e., most of energy injected at e(M sub e)(C sup 2) is realized in the accretion shock model of Kazanas and Ellison. This mechanism involves only one free parameter the compactness of the sources, L/R, whose mean value can also account for the diffuse gamma ray background in terms of AGNs.

  9. AGN feedback in the Perseus cluster

    NASA Astrophysics Data System (ADS)

    Gendron-Marsolais, Marie-Lou; Hlavacek-Larrondo, Julie; Clarke, Tracy E.; Intema, Huib; Fabian, Andrew C.; Taylor, Gregory B.; Blundell, Katherine

    2016-04-01

    Deep Chandra images of the Perseus cluster of galaxies have revealed a succession of cavities created by the jets of the central supermassive black hole, pushing away the X-ray emitting gas and leaving bubbles filled with radio emission. Perseus is one of the rare examples showing buoyantly rising lobes from past radio outbursts, characterized by a steep spectral index and known as ghost cavities. All of these structures trace the complete history of mechanical AGN feedback over the past 500 Myrs. I will present results on new, ultra deep 230-470 MHz JVLA data. This low-frequency view of the Perseus cluster will probe the old radio-emitting electron population and will allow us to build the most detailed map of AGN feedback in a cluster thus far.

  10. THE ROLE OF STAR FORMATION AND AN AGN IN DUST HEATING OF z = 0.3–2.8 GALAXIES. I. EVOLUTION WITH REDSHIFT AND LUMINOSITY

    SciTech Connect

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric; Yan, Lin; Armus, Lee; Díaz-Santos, Tanio; Stierwalt, Sabrina

    2015-11-20

    We characterize infrared spectral energy distributions of 343 (ultra)luminous infrared galaxies from z = 0.3–2.8. We diagnose the presence of an active galactic nucleus (AGN) by decomposing individual Spitzer mid-IR spectroscopy into emission from star formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGNs, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright S{sub 24}, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2–1000 μm). We fit the far-IR emission using a two-temperature modified blackbody to measure cold and warm dust temperatures (T{sub c} and T{sub w}). We find that T{sub c} does not depend on mid-IR classification, while T{sub w} shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to L{sub IR}. AGNs, composites, and SFGs separate in S{sub 8}/S{sub 3.6} and S{sub 250}/S{sub 24}, providing a useful diagnostic for estimating relative amounts of these sources. We estimate that >40% of IR-selected samples host an AGN, even at faint selection thresholds (S{sub 24} > 100 μJy). Our decomposition technique and color diagnostics are relevant given upcoming observations with the James Webb Space Telescope.

  11. Jets in AGN at extremely high redshifts

    NASA Astrophysics Data System (ADS)

    Gurvits, Leonid I.; Frey, Sándor; Paragi, Zsolt

    2015-03-01

    The jet phenomenon is a trademark of active galactic nuclei (AGN). In most general terms, the current understanding of this phenomenon explains the jet appearance by effects of relativistic plasma physics. The fundamental source of energy that feeds the plasma flow is believed to be the gravitational field of a central supermassive black hole. While the mechanism of energy transfer and a multitude of effects controlling the plasma flow are yet to be understood, major properties of jets are strikingly similar in a broad range of scales from stellar to galactic. They are supposed to be controlled by a limited number of physical parameters, such as the mass of a central black hole and its spin, magnetic field induction and accretion rate. In a very simplified sense, these parameters define the formation of a typical core-jet structure observed at radio wavelengths in the region of the innermost central tens of parsecs in AGN. These core-jet structures are studied in the radio domain by Very Long Baseline Interferometry (VLBI) with milli- and sub-milliarcsecond angular resolution. Such structures are detectable at a broad range of redshifts. If observed at a fixed wavelength, a typical core-jet AGN morphology would appear as having a steep-spectrum jet fading away with the increasing redshift while a flat-spectrum core becoming more dominant. If core-jet AGN constitute the same population of objects throughout the redshift space, the apparent ``prominence'' of jets at higher redshifts must decrease (Gurvits 1999): well pronounced jets at high z must appear less frequent than at low z.

  12. Challenges in Finding AGNs in the Low Luminosity Regime

    NASA Astrophysics Data System (ADS)

    Satyapal, Shobita; Abel, Nick; Secrest, Nathan; Singh, Amrit; Ellison, Sara

    2016-08-01

    Low luminosity AGNs are an important component of the AGN population. They are often found in the lowest mass galaxies or galaxies that lack classical bulges, a demographic that places important constraints to models of supermassive black hole seed formation and merger-free models of AGN fueling. The detection of AGNs in this low luminosity regime is challenging both because star formation in the host galaxy can dominate the optical spectrum and gas and dust can obscure the central engine at both optical and X-ray wavelengths. Thus while mid-infrared color selection and X-ray observations at energies <10 keV are often powerful tools in uncovering optically unidentified AGNs at higher luminosities, this is not the case in the low luminosity regime. In this talk, I will review the effectiveness of uncovering AGNs in the low luminosity regime using multiwavength investigations, with a focus on infrared spectroscopic signatures.

  13. The host galaxies of X-ray selected AGN: feeding and feedback

    NASA Astrophysics Data System (ADS)

    Merloni, A.; Bongiorno, A.

    2014-07-01

    Using the rich multi-band photometry in the COSMOS field we explore the host galaxy properties of a large, complete, sample of X-ray and spectroscopically selected AGN. Based on a two-components fit to their Spectral Energy Distribution, we derive rest-frame magnitudes, colors, stellar masses and star formation rates up to z˜3, and we study the connection between these host galaxy properties, accretion luminosity and obscuration in galactic nuclei across more than 2/3 of the age of the Universe. Although AGN activity and star formation appear to have a common triggering mechanism, we do not find any strong evidence signaling the influence of luminous AGN on the global properties of their host galaxies. Conversely, we found that the central black hole activity have profound effects on the surrounding matter on scales comparable to the gravitational sphere of influence of the black hole. We discuss the implication of our findings for the nature of the long sough-after 'Quasar mode' feedback from AGN.

  14. Delving into X-ray obscuration of type 2 AGN, near and far

    SciTech Connect

    LaMassa, Stephanie M.; Meg Urry, C.; Yaqoob, Tahir; Ptak, Andrew F.; Gandhi, Poshak

    2014-05-20

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O III] 5007 Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate 'naked' Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L{sub 2-10} {sub keV,} {sub in}) to L{sub [O} {sub III]} is 1.54 ± 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe Kα luminosity is significantly correlated with L{sub [O} {sub III]} but with substantial scatter. Finally, we do not find a trend between L {sub 2-10keV,} {sub in} and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift.

  15. Delving Into X-ray Obscuration of Type 2 AGN, Near and Far

    NASA Astrophysics Data System (ADS)

    LaMassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew F.; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Meg Urry, C.

    2014-05-01

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O III] 5007 Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate "naked" Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L 2-10 keV, in) to L [O III] is 1.54 ± 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe Kα luminosity is significantly correlated with L [O III] but with substantial scatter. Finally, we do not find a trend between L 2-10 keV, in and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift.

  16. Unification of Low Luminosity AGN and Hard State X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Connolly, S.

    2015-09-01

    We present X-ray spectral variability of four low accretion rate and low luminosity AGN (LLAGN)- M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the 'softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely cause of spectral variability is found to be hardening of the photon index of the power law component with increasing luminosity. Such a correlation has been seen previously within samples of low accretion rate AGN but in only one case has it been seen within observations of a single AGN. Here we show that such behaviour may be very common in LLAGN. A similar anticorrelation is found in X-ray binary systems in the 'hard state', at low accretion rates similar to those of the LLAGN discussed here. Our observations thus imply that LLAGN are the active galaxy equivalent of hard state X-ray binaries.

  17. Delving into X-Ray Obscuration of Type 2 AGN, Near and Far

    NASA Technical Reports Server (NTRS)

    Lamassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew F.; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Urry, C. Meg

    2014-01-01

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O iii] 5007Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate "naked" Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L2-10 keV,in) to L[O iii] is 1.54 +/- 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe K(alpha) luminosity is significantly correlated with L[O iii] but with substantial scatter. Finally, we do not find a trend between L2-10 keV,in and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift. Key words: galaxies: active - galaxies: Seyfert - X-rays: general

  18. VLP - High-Redshift AGNs and the X-SERVS Survey

    NASA Astrophysics Data System (ADS)

    Brandt, W.

    2016-06-01

    In the first part of this talk, I will review how X-ray observations of high-redshift AGNs at z = 4-7 have played a critical role in understanding their basic demographics as well as their physical processes; e.g., accretion rates, jet emission, X-ray absorption by nuclear material and winds. Since 2000, XMM-Newton and Chandra have provided new X-ray detections for more than 120 such objects, and well-defined samples of z > 4 AGNs now allow reliable basic X-ray population studies. I will point out key remaining areas of uncertainty, highlighting where further XMM-Newton and Chandra observations can advance understanding. I will then describe the X-SERVS project which aims to go ``beyond COSMOS'' via a 12 deg^2 survey of three prime sky regions: W-CDF-S, XMM-LSS, and ELAIS-S1. The X-SERVS survey will allow outstanding studies of the detected AGNs and groups/clusters by powerfully leveraging multiple intensive radio-to-UV surveys: ATLAS/HerMES/SERVS/VIDEO/DES/HSC/PS1MD/VOICE/CSI/PRIMUS. We aim to dramatically advance studies of SMBH growth across the full range of cosmic environments, links between SMBH accretion and star formation, exceptional AGNs at high redshifts, protoclusters, etc. The targeted X-SERVS fields will have extraordinary legacy value as MOONS massive spectroscopy fields, prime ALMA fields, and DES/LSST deep-drilling fields.

  19. AGN Feedback: Radio-Loudness Distribution and the Kinetic Luminosity function

    NASA Astrophysics Data System (ADS)

    La Franca, Fabio; Melini, Gabriele; Fiore, Fabrizio

    We have studied the AGN radio emission from the largest existing compilation of hard X-ray selected samples, all observed in the 1.4 GHz band. A total of more than 1600 AGN have been used. For the first time, it was possible to almost completely measure the probability distribution function of the ratio between the radio and the X-ray luminosity RX , which has been function-ally fitted as dependent from the X-ray luminosity and redshift. These measures have allowed us to estimate the AGN kinetic luminosity function and its evo-lution. It results that, in agreement with previous estimates, the efficiency kin in converting the accreted mass energy into kinetic power (LK = kin mc2 ) is on average kin ˜5 × 10-3 . ˙ The derived value and evolution of the kinetic energy density is in qualitative agreement with some of the last generation galaxy evolution models, where radio mode AGN feedback is invoked to quench the star formation in galaxies and slow down the cooling flows in galaxy clusters.

  20. The spatial distribution of X-ray selected AGN in the Chandra deep fields: a theoretical perspective

    NASA Astrophysics Data System (ADS)

    Marulli, Federico; Bonoli, Silvia; Branchini, Enzo; Gilli, Roberto; Moscardini, Lauro; Springel, Volker

    2009-07-01

    We study the spatial distribution of X-ray selected active galactic nuclei (AGN) in the framework of hierarchical coevolution of supermassive black holes and their host galaxies and dark matter haloes. To this end, we have applied the theoretical model developed by Croton et al., De Lucia & Blaizot and Marulli et al. to the output of the Millennium Run and obtained hundreds of realizations of past light cones from which we have extracted realistic mock AGN catalogues that mimic the Chandra deep fields. We find that the model AGN number counts are in fair agreement with observations both in the soft and in the hard X-ray bands, except at fluxes <~10-15ergcm-2s-1, where the model systematically overestimates the observations. However, a large fraction of these faint objects are typically excluded from the spectroscopic AGN samples of the Chandra fields. We find that the spatial two-point correlation function predicted by the model is well described by a power-law relation out to 20h-1Mpc, in close agreement with observations. Our model matches the correlation length r0 of AGN in the Chandra Deep Field-North but underestimates it in the Chandra Deep Field-South. When fixing the slope to γ = 1.4, as in Gilli et al., the statistical significance of the mismatch is 2σ-2.5σ, suggesting that the predicted cosmic variance, which dominates the error budget, may not account for the different correlation length of the AGN in the two fields. However, the overall mismatch between the model and the observed correlation function decreases when both r0 and γ are allowed to vary, suggesting that more realistic AGN models and a full account of all observational errors may significantly reduce the tension between AGN clustering in the two fields. While our results are robust to changes in the model prescriptions for the AGN light curves, the luminosity dependence of the clustering is sensitive to the different light-curve models adopted. However, irrespective of the model

  1. Herschel Observed Stripe 82 Quasars and Their Host Galaxies: Connections between AGN Activity and host Galaxy Star Formation

    NASA Astrophysics Data System (ADS)

    Dong, X. Y.; Wu, Xue-Bing

    2016-06-01

    In this work, we present a study of 207 quasars selected from the Sloan Digital Sky Survey quasar catalogs and the Herschel Stripe 82 survey. Quasars within this sample are high-luminosity quasars with a mean bolometric luminosity of 1046.4 erg s-1. The redshift range of this sample is within z < 4, with a mean value of 1.5 ± 0.78. Because we only selected quasars that have been detected in all three Herschel-SPIRE bands, the quasar sample is complete yet highly biased. Based on the multi-wavelength photometric observation data, we conducted a spectral energy distribution (SED) fitting through UV to FIR. Parameters such as active galactic nucleus (AGN) luminosity, far-IR (FIR) luminosity, stellar mass, as well as many other AGN and galaxy properties are deduced from the SED fitting results. The mean star formation rate (SFR) of the sample is 419 M ⊙ yr-1 and the mean gas mass is ˜1011.3 M ⊙. All of these results point to an IR luminous quasar system. Compared with star formation main sequence (MS) galaxies, at least 80 out of 207 quasars are hosted by starburst galaxies. This supports the statement that luminous AGNs are more likely to be associated with major mergers. The SFR increases with the redshift up to z = 2. It is correlated with the AGN bolometric luminosity, where {L}{{FIR}}\\propto {L}{{Bol}}0.46+/- 0.03. The AGN bolometric luminosity is also correlated with the host galaxy mass and gas mass. Yet the correlation between L FIR and L Bol has higher significant level, implies that the link between AGN accretion and the SFR is more primal. The M BH/M * ratio of our sample is 0.02, higher than the value 0.005 in the local universe. It might indicate an evolutionary trend of the M BH-M * scaling relation.

  2. AGN Black Hole Masses from Reverberation Mapping

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.

    2004-01-01

    Emission-line variability data on bright AGNs indicates that the central objects in these sources have masses in the million to few-hundred million solar mass range. The time-delayed response of the emission lines to continuum variations can be used to infer the size of the line-emitting region via light travel-time arguments. By combining these sizes with the Doppler widths of the variable part of the emission lines, a virial mass estimate can be obtained. For three especially well-studied sources, NGC 5548, NGC 7469, and 3C 390.3, data on multiple emission lines can be used to test the virial hypothesis. In each of these cases, the response time of the various emission lines is anticorrelated with the line width, with the dependence as expected for gravitationally bound motion of the line-emitting clouds, i.e., that the square of the Doppler line width is inversely proportional to the emission-line time delay. Virial masses based on the Balmer lines have now been measured for about three dozen AGNs. Systematic effects currently limit the accuracy of these masses to a factor of several, but characteristics of the radius-luminosity and mass-luminosity relationships for AGNs are beginning to emerge.

  3. Discovery of a population of bulgeless galaxies with extremely red MID-IR colors: Obscured AGN activity in the low-mass regime?

    SciTech Connect

    Satyapal, S.; Secrest, N. J.; McAlpine, W.; Rosenberg, J. L.; Ellison, S. L.; Fischer, J.

    2014-04-01

    In contrast to massive, bulge hosting galaxies, very few supermassive black holes (SMBHs) are known in either low-mass or bulgeless galaxies. Such a population could provide clues to the origins of SMBHs and to secular pathways for their growth. Using the all-sky Wide-field Infrared Survey Explorer (WISE ) survey, and bulge-to-disk decompositions from the Sloan Digital Sky Survey (SDSS) Data Release 7, we report the discovery of a population of local (z < 0.3) bulgeless disk galaxies with extremely red mid-infrared colors which are highly suggestive of a dominant active galactic nucleus (AGN), despite having no optical AGN signatures in their SDSS spectra. Using various mid-infrared selection criteria from the literature, there are between 30 and over 300 bulgeless galaxies with possible AGNs. Other known scenarios that can heat the dust to high temperatures do not appear to explain the observed colors of this sample. If these galaxies are confirmed to host AGNs, this study will provide a breakthrough in characterizing the properties of SMBHs in the low bulge mass regime and in understanding their relation with their host galaxies. Mid-infrared selection identifies AGNs that dominate their host galaxy's emission and therefore reveal a different AGN population than that uncovered by optical studies. We find that the fraction of all galaxies identified as candidate AGNs by WISE is highest at lower stellar masses and drops dramatically in higher mass galaxies, in striking contrast to the findings from optical studies.

  4. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    NASA Astrophysics Data System (ADS)

    Cappi, M.; Tombesi, F.; Giustini, M.

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  5. Feedback in the local Universe: Relation between star formation and AGN activity in early type galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher; Baum, Stefi; Jones, Christine; Forman, William; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2015-08-01

    Aim: We address the relation between star formation and AGN activity in a large sample of nearby early type (E and S0) galaxies. The redshift range of the galaxies is 0.0002AGN is believed to play an important role in regulating star formation and thus the process of galaxy evolution and formation. Evidence of AGN feedback is found in massive galaxies in galaxy clusters. However, how common AGN feedback is in the local universe and in small scale systems is still not evident.Methods: To answer this question, we carried out a multiple wavelength study of a sample of 231 early type galaxies which were selected to have an apparent K-band magnitude brighter than 13.5 and whose positions correlate with Chandra ACIS-I and ACIS-S sources. The galaxies in the sample are unbiased regarding their star formation and radio source properties. Using the archival observations at radio, IR and UV from VLA, WISE and GALEX respectively, we obtained the radio power, estimate FUV star formation rate (SFR) and other galaxy properties to study AGN activity and ongoing star formation.Results: The relationship between radio power and stellar mass shows that there is an upper envelope of radio power that is a steep function of stellar luminosity. This suggests that less massive galaxies have low radio power while massive galaxies are capable of hosting powerful radio sources. The Radio-MIR relation shows that galaxies with P>=1022 WHz-1 are potential candidates for being AGN. About ~ 7% of the sample show evidence of ongoing star formation with SFR ranging from 10-3 to 1 M⊙yr-1. These are also less massive and radio faint suggesting the absence of active accretion. There is nearly equal fraction of star forming galaxies in radio faint (P<1022 WHz-1) and radio bright galaxies (P>=1022 WHz-1) . Only ~ 5% of the galaxies in our sample have P>=1022 WHz-1 and most of them do not show evidence of bright accretion disks. We see a weak correlation and a dispersion of

  6. Hot Dust Obscured Galaxies with Excess Blue Light: Dual AGN or Single AGN Under Extreme Conditions?

    NASA Astrophysics Data System (ADS)

    Assef, R. J.; Walton, D. J.; Brightman, M.; Stern, D.; Alexander, D.; Bauer, F.; Blain, A. W.; Diaz-Santos, T.; Eisenhardt, P. R. M.; Finkelstein, S. L.; Hickox, R. C.; Tsai, C.-W.; Wu, J. W.

    2016-03-01

    Hot dust-obscured galaxies (Hot DOGs) are a population of hyper-luminous infrared galaxies identified by the Wide-field Infrared Survey Explorer (WISE) mission from their very red mid-IR colors, and characterized by hot dust temperatures (T > 60 K). Several studies have shown clear evidence that the IR emission in these objects is powered by a highly dust-obscured active galactic nucleus (AGN) that shows close to Compton-thick absorption at X-ray wavelengths. Thanks to the high AGN obscuration, the host galaxy is easily observable, and has UV/optical colors usually consistent with those of a normal galaxy. Here we discuss a sub-population of eight Hot DOGs that show enhanced rest-frame UV/optical emission. We discuss three scenarios that might explain the excess UV emission: (i) unobscured light leaked from the AGN by reflection over the dust or by partial coverage of the accretion disk; (ii) a second unobscured AGN in the system; or (iii) a luminous young starburst. X-ray observations can help discriminate between these scenarios. We study in detail the blue excess Hot DOG WISE J020446.13-050640.8, which was serendipitously observed by Chandra/ACIS-I for 174.5 ks. The X-ray spectrum is consistent with a single, hyper-luminous, highly absorbed AGN, and is strongly inconsistent with the presence of a secondary unobscured AGN. Based on this, we argue that the excess blue emission in this object is most likely either due to reflection or a co-eval starburst. We favor the reflection scenario as the unobscured star formation rate needed to power the UV/optical emission would be ≳1000 M⊙ yr-1. Deep polarimetry observations could confirm the reflection hypothesis.

  7. Time Series Analysis of the UV Flickering in AGN

    NASA Technical Reports Server (NTRS)

    Robinson, Edward L.

    2003-01-01

    Goals of the Research: Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability.

  8. The AGN origin of cluster magnetic fields

    NASA Astrophysics Data System (ADS)

    Xu, Hao

    The origin of magnetic fields in galaxy clusters is one of the most fascinating but challenging problems in astrophysics. In this dissertation, the possibility of an Active Galactic Nucleus (AGN) origin of cluster magnetic fields is studied through state of the art simulations of magnetic field evolution in large scale structure formation using a newly developed cosmological Adaptive Mesh Refinement (AMR) Magnetohydrodynamics (MHD) code -- EnzoMHD. After presenting a complete but concise description and verification of the code, we discuss the creation of magnetic fields through the Biermann Battery effect during first star formation and galaxy cluster formation. We find that magnetic fields are produced as predicted by theory in both cases. For the first star formation, we obtain a lower limit of (~ 10 -9 G) for magnetic fields when the first generation stars form. On the other hand, we find that the magnetic energy is amplified 4 orders of magnitude within ~ 10 Gyr during cluster formation. We then study magnetic field injection from AGN into the Intra- Cluster Medium (ICM) and their impact on the ICM. We reproduce the X-ray cavities as well as weak shocks seen in observations in the simulation, and further confirm the idea that AGN outburst must contain lots of magnetic energy (up to 10 61 ergs) and the magnetic fields play an important part in the formation of jet/lobe system. We present high resolution simulations of cluster formation with magnetic fields injected from high redshift AGN. We find that these local magnetic fields are spread quickly throughout the whole cluster by cluster mergers. The ICM is in a turbulent state with a Kolmogorov-like power spectrum. Magnetic fields are amplified to and maintained at the observational level of a few mG by bulk flows at large scale and the ICM turbulence at small scale. The total magnetic energy increases about 25 times to ~ 1.2 × 10^61 ergs at the present time. We conclude that magnetic fields from AGN at high

  9. The clustering amplitude of X-ray-selected AGN at z ˜ 0.8: evidence for a negative dependence on accretion luminosity

    NASA Astrophysics Data System (ADS)

    Mountrichas, G.; Georgakakis, A.; Menzel, M.-L.; Fanidakis, N.; Merloni, A.; Liu, Z.; Salvato, M.; Nandra, K.

    2016-04-01

    The northern tile of the wide-area and shallow XMM-XXL X-ray survey field is used to estimate the average dark matter halo mass of relatively luminous X-ray-selected active galactic nucleus (AGN) [log {L}_X (2-10 keV)= 43.6^{+0.4}_{-0.4} erg s^{-1}] in the redshift interval z = 0.5-1.2. Spectroscopic follow-up observations of X-ray sources in the XMM-XXL field by the Sloan telescope are combined with the VIMOS Public Extragalactic Redshift Survey spectroscopic galaxy survey to determine the cross-correlation signal between X-ray-selected AGN (total of 318) and galaxies (about 20 000). We model the large scales (2-25 Mpc) of the correlation function to infer a mean dark matter halo mass of log M / (M_{{⊙}} h^{-1}) = 12.50 ^{+0.22} _{-0.30} for the X-ray-selected AGN sample. This measurement is about 0.5 dex lower compared to estimates in the literature of the mean dark matter halo masses of moderate-luminosity X-ray AGN [LX(2-10 keV) ≈ 1042-1043 erg s- 1] at similar redshifts. Our analysis also links the mean clustering properties of moderate-luminosity AGN with those of powerful ultraviolet/optically selected QSOs, which are typically found in haloes with masses few times 1012 M⊙. There is therefore evidence for a negative luminosity dependence of the AGN clustering. This is consistent with suggestions that AGN have a broad dark matter halo mass distribution with a high mass tail that becomes subdominant at high accretion luminosities. We further show that our results are in qualitative agreement with semi-analytic models of galaxy and AGN evolution, which attribute the wide range of dark matter halo masses among the AGN population to different triggering mechanisms and/or black hole fuelling modes.

  10. Radio AGN signatures in massive quiescent galaxies out to z=1.5

    NASA Astrophysics Data System (ADS)

    Järvelä, Emilia

    2016-08-01

    Detection of gamma-rays from narrow-line Seyfert 1 galaxies (NLS1) by Fermi confirmed the presence of powerful relativistic jets in them, and thus challenged our understanding of active galactic nuclei (AGN). In the current AGN paradigm powerful relativistic jets are produced in massive elliptical galaxies with supermassive black holes. NLS1s differ from them significantly; they harbour lower mass black holes accreting at higher Eddington ratios, have preferably compact radio morphology, reside mostly in spiral galaxies, and were thought to be radio-quiet.Fermi's discovery invokes questions about the AGN evolution; what triggers and maintains the AGN activity, and what are the evolutionary lines of the different populations? It is also necessary to revise the AGN unification schemes to fit in NLS1s. They convolute the whole AGN scenario, but offer us a new look on the jet phenomena and will help us construct a more comprehensive big picture of AGN.Despite their importance, NLS1s are rather poorly studied as a class. For example, some NLS1s seem to be totally radio-silent, but a considerable fraction are radio-loud and thus probably host jets. This, along with other observational evidence, implies that they do not form a homogeneous class. However, it remains unclear what is triggering the radio loudness in some of them, but, for example, the properties of the host galaxy and the large-scale environment might play a role. Also the parent population of NLS1s remains an open question.We used various statistical methods, for example, multiwavelength correlations and principal component analysis to study a large sample of NLS1 sources. We will present the results and discuss the interplay between their properties, such as emission properties, black hole masses, large-scale environments, and their effect on radio loudness. We will also introduce the Metsähovi Radio Observatory NLS1 galaxy observing programme, which is the first one dedicated to systematical observations

  11. The Nature of Soft X-ray Emission in Obscured AGN

    NASA Astrophysics Data System (ADS)

    Guainazzi, M.

    2006-08-01

    We present results of a high-resolution soft X-ray (0.2 - 2 keV) spectroscopic study on a sample of 66 nearby obscured AGN observed by the Reflection Grating Spectrometer (RGS) on board XMM-Newton. This is the largest sample ever studied with this technique so far. The main conclusions of our study can be summarized as follows: a) narrow Radiative Recombination Continua are detected in 40% of the objects in our sample; in 27% their width is ≤ 10 eV; b) higher order transitions are generally enhanced with respect to pure photoionization, indicating that resonant scattering plays an important role in the ionization/excitation balance. These results support the scenario whereby the active nucleus is responsible for the X-ray 'soft excess' almost ubiquitously observed in nearby obscured AGN via photoionization of circumnuclear gas. They confirm on a statistical basis the conclusions drawn from the detailed study of the brightest spectra in the sample. Furthermore, we propose a criterion to statistically discriminate between AGN-photoionized sources and starbursts galaxies, based on intensity of the forbidden component of the OVII He-alpha triplet (once normalized to the OVIII Ly-alpha) coupled with the integrated luminosity in He-like and H-like oxygen lines.

  12. Unveiling the AGN activity in multiple SMBH systems: the remarkable case of SDSS J0959+1259

    NASA Astrophysics Data System (ADS)

    De Rosa, A.; Magna Team

    2016-06-01

    In this talk we will present results from the MAGNA (Multiple AGN Activity) project focused on the detection and study of multiple supermassive BH systems. We aim at studying the physical properties of multiple AGN candidates in interacting/disturbed systems from both an observational and a theoretical point of view. The final goal is to understand the possible mechanisms that could relate the triggering of AGN activity with the different stages of galaxies mergers. The MAGNA project includes the study of several samples of dual AGN, extracted from different wavebands, supplied by an extensive set of multiwavelength observations granted to our team by MUSE, XMM, VLA as well as available in archives. This strategy allowed us to identify a galaxy compact group (CG SDSS J0959+1259) that appears exceptional having a high concentration of nuclear activity. We present here the multi-wavelength study of this CG through XMM, SDSS and BUSCA data. The XMM analysis extends and modifies the previous identification of the members of this group, which is composed of 3 Compton thin AGN, 2 LINERs and 3 star forming region.

  13. The Close AGN Reference Survey (CARS). Mrk 1018 returns to the shadows after 30 years as a Seyfert 1

    NASA Astrophysics Data System (ADS)

    McElroy, R. E.; Husemann, B.; Davis, T. A.; Bennert, V. N.; Busch, G.; Combes, F.; Eckart, A.; Perez-Torres, M.; Powell, M.; Scharwächter, J.; Tremblay, G. R.; Urrutia, T.

    2016-09-01

    We report the discovery that the known "changing look" AGN Mrk 1018 has changed spectral type for a second time. New VLT-MUSE data taken in 2015 as part of the Close AGN Reference Survey (CARS) shows that the AGN has returned to its original Seyfert 1.9 classification. The CARS sample is selected to contain only bright type 1 AGN, but Mrk 1018's broad emission lines and continuum, typical of type 1 AGN, have almost entirely disappeared. We use spectral fitting of the MUSE spectrum and previously available spectra to determine the drop in broad line flux and the Balmer decrement. We find that the broad line flux has decreased by a factor of 4.75 ± 0.5 in Hα since an SDSS spectrum was taken in 2000. The Balmer decrement has not changed significantly implying no enhanced reddening with time, but the remaining broad lines are more asymmetric than those present in the type 1 phase. We posit that the change is due to an intrinsic drop in flux from the accretion disk rather than variable extinction or a tidal disruption event.

  14. Warm Absorber Diagnostics of AGN Dynamics

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  15. Using the Bright Ultrahard XMM-Newton survey to define an IR selection of luminous AGN based on WISE colours

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Alonso-Herrero, A.; Carrera, F. J.; Blain, A.; Watson, M. G.; Barcons, X.; Braito, V.; Severgnini, P.; Donley, J. L.; Stern, D.

    2012-11-01

    We present a highly complete and reliable mid-infrared (MIR) colour selection of luminous active galactic nucleus (AGN) candidates using the 3.4, 4.6 and 12 μm bands of the Wide-field Infrared Survey Explorer (WISE) survey. The MIR colour wedge was defined using the wide-angle Bright Ultrahard XMM-Newton survey (BUXS), one of the largest complete flux-limited samples of bright (f4.5-10 keV >6×10-14 erg s-1 cm -2) 'ultrahard' (4.5-10 keV) X-ray-selected AGN to date. The BUXS includes 258 objects detected over a total sky area of 44.43 deg2 of which 251 are spectroscopically identified and classified, with 145 being type 1 AGN and 106 type 2 AGN. Our technique is designed to select objects with red MIR power-law spectral energy distributions (SEDs) in the three shortest bands of WISE and properly accounts for the errors in the photometry and deviations of the MIR SEDs from a pure power-law. The completeness of the MIR selection is a strong function of luminosity. At L2-10 keV >1044 erg s-1, where the AGN is expected to dominate the MIR emission, 97.1-4.8+2.2 and 76.5-18.4+13.3 per cent of the BUXS type 1 and type 2 AGN, respectively, meet the selection. Our technique shows one of the highest reliability and efficiency of detection of the X-ray-selected luminous AGN population with WISE amongst those in the literature. In the area covered by BUXS our selection identifies 2755 AGN candidates detected with signal-to-noise ratio ≥5 in the three shorter wavelength bands of WISE with 38.5 per cent having a detection at 2-10 keV X-ray energies. We also analysed the possibility of including the 22 μm WISE band to select AGN candidates, but neither the completeness nor the reliability of the selection improves. This is likely due to both the significantly shallower depth at 22 μm compared with the first three bands of WISE and star formation contributing to the 22 μm emission at the WISE 22 μm sensitivity.

  16. The AGN Content of the Micron all Sky Survey

    NASA Astrophysics Data System (ADS)

    Cutri, R. M.

    2000-01-01

    The Two Micron All Sky Survey (2MASS) began routine operations from its northern facility on Mt. Hopkins, AZ in June of 1997, and from its southern facility on Cerro Tololo, Chile in March of 1998. At each site, highly automated 1.3 m telescopes equipped with identical 3-channel cameras, are systematically imaging the sky in three near infrared wavelength bands, J (1.25 um), H (1.65 um) and K-s (2.17 um). The Survey will ultimately produce an Image Atlas containing nearly two million 512 x 1024 pixel images (1 arcsec/pix) in the three colors, a highly complete and reliable catalog containing approx. 300 million point sources having SNR greater than 10 photometry at J less or = 15.8, H less or = 15.1 and K-s less or = 14.3 mag. and an astrometric accuracy greater than 0.511 RMS, and a catalog of 1-2 million resolved sources, primarily galaxies, having SNR greater than 10 photometric accuracy at J less than or = 15.5, H less than or = 14.8 and K-s less than or = 13.5 mag. The 2MASS Sampler, an introductory set of data, was released to the community in December of 1998 (see http://www.ipac.caltech.edu/2mass/). We review the near IR and optical/IR properties of "conventional" QSOs from UV and optical samples, and estimate the number that will be detected by 2MASS. We also discuss 2MASS's ability to test for for new populations of extremely red AGN that have been missed by UV and Visual surveys, as suggested by from IRAS and radio studies. Results of spectroscopic follow-up of 2MASS-selected new AGN candidates will also be presented.

  17. AGN disks and black holes on the weighting scales

    NASA Astrophysics Data System (ADS)

    Huré, J.-M.; Hersant, F.; Surville, C.; Nakai, N.; Jacq, T.

    2011-06-01

    We exploit our formula for the gravitational potential of finite size, power-law disks to derive a general expression linking the mass of the black hole in active galactic nuclei (AGN), the mass of the surrounding disk, its surface density profile (through the power index s), and the differential rotation law. We find that the global rotation curve v(R) of the disk in centrifugal balance does not obey a power law of the cylindrical radius R (except in the confusing case s = -2 that mimics a Keplerian motion), and discuss the local velocity index. This formula can help to understand how, from position-velocity diagrams, mass is shared between the disk and the black hole. To this purpose, we checked the idea by generating a sample of synthetic data with different levels of Gaussian noise, added in radius. It turns out that, when observations are spread over a large radial domain and exhibit low dispersion (standard deviation σ ≲ 10% typically), the disk properties (mass and s-parameter) and black hole mass can be deduced from a non linear fit of kinematic data plotted on a (R,Rv2)-diagram. For σ ≳ 10%, masses are estimated fairly well from a linear regression (corresponding to the zeroth-order treatment of the formula), but the power index s is no longer accessible. We have applied the model to 7 AGN disks whose rotation has already been probed through water maser emission. For NGC 3393 and UGC 3789, the masses seem well constrained through the linear approach. For IC 1481, the power-law exponent s can even be deduced. Because the model is scale-free, it applies to any kind of star/disk system. Extension to disks around young stars showing deviation from Keplerian motion is thus straightforward.

  18. Baldwin Effect and Additional BLR Component in AGN with Superluminal Jets

    NASA Astrophysics Data System (ADS)

    Patiño Álvarez, Víctor; Torrealba, Janet; Chavushyan, Vahram; Cruz González, Irene; Arshakian, Tigran; León Tavares, Jonathan; Popovic, Luka

    2016-06-01

    We study the Baldwin Effect (BE) in 96 core-jet blazars with optical and ultraviolet spectroscopic data from a radio-loud AGN sample obtained from the MOJAVE 2cm survey. A statistical analysis is presented of the equivalent widths W_lambda of emission lines H beta 4861, Mg II 2798, C IV 1549, and continuum luminosities at 5100, 3000, and 1350 angstroms. The BE is found statistically significant (with confidence level c.l. > 95%) in H beta and C IV emission lines, while for Mg II the trend is slightly less significant (c.l. = 94.5%). The slopes of the BE in the studied samples for H beta and Mg II are found steeper and with statistically significant difference than those of a comparison radio-quiet sample. We present simulations of the expected BE slopes produced by the contribution to the total continuum of the non-thermal boosted emission from the relativistic jet, and by variability of the continuum components. We find that the slopes of the BE between radio-quiet and radio-loud AGN should not be different, under the assumption that the broad line is only being emitted by the canonical broad line region around the black hole. We discuss that the BE slope steepening in radio AGN is due to a jet associated broad-line region.

  19. Relativistic Effects on the Observed AGN Luminosity Distribution

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Zhang, Shuang Nan; Zhang, Xiao Ling

    2007-02-01

    Recently, Zhang (2005 ApJ, 618, L79) has proposed a model to account for the well-established effect that the fraction of type-II AGNs is anti-correlated with the observed X-ray luminosity; the model consists of an X-ray emitting accretion disk coaligned to the dusty torus within the standard AGN unification model. In this paper the model is refined by including relativistic effects of the observed X-ray radiation from the vicinity of the supermassive black hole in an AGN. The relativistic corrections improve the combined fitting results of the observed luminosity distribution and the type-II AGN fraction, though the improvement is not significant. The type-II AGN fraction prefers non- or mildly spinning black hole cases, and rules out the extremely spinning case.

  20. Tools for Computing the AGN Feedback: Radio-loudness Distribution and the Kinetic Luminosity Function

    NASA Astrophysics Data System (ADS)

    La Franca, F.; Melini, G.; Fiore, F.

    2010-07-01

    We studied the active galactic nucleus (AGN) radio emission from a compilation of hard X-ray-selected samples, all observed in the 1.4 GHz band. A total of more than 1600 AGNs with 2-10 keV de-absorbed luminosities higher than 1042 erg s-1 cm-2 were used. For a sub-sample of about fifty z <~ 0.1 AGNs, it was possible to reach ~80% of radio detections and therefore, for the first time, it was possible to almost completely measure the probability distribution function of the ratio between the radio and the X-ray luminosity RX = log(L 1.4/LX ), where L 1.4/LX = νL ν(1.4 GHz)/LX (2-10 keV). The probability distribution function of RX was functionally fitted as dependent on the X-ray luminosity and redshift, P(RX |LX , z). It roughly spans over six decades (-7< RX <-1) and does not show any sign of bi-modality. The result is that the probability of finding large values of the RX ratio increases with decreasing X-ray luminosities and (possibly) with increasing redshift. No statistically significant difference was found between the radio properties of the X-ray absorbed (N H>1022 cm-2) and un-absorbed AGNs. Measurement of the probability distribution function of RX allowed us to compute the kinetic luminosity function and the kinetic energy density which, at variance with that assumed in many galaxy evolution models, is observed to decrease by about a factor of 5 at redshift below 0.5. About half of the kinetic energy density results in being produced by the more radio quiet (RX <-4) AGNs. In agreement with previous estimates, the AGN efficiency epsilonkin in converting the accreted mass energy into kinetic power (L_K=ɛ_kin\\dot{m} c^2) is, on average, epsilonkin ~= 5 × 10-3. The data suggest a possible increase of epsilonkin at low redshifts.

  1. NuSTAR Survey of Swift/BAT AGN as a Probe of the Unified Model

    NASA Astrophysics Data System (ADS)

    Balokovic, M.

    2015-09-01

    NuSTAR has enabled studies of the local AGN to extend into the spectral window above 10 keV with unprecedented spatial resolution and two orders of magnitude better sensitivity than any other instrument operating in that energy range. As a part of its long-term extragalactic program NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift/BAT instrument. We present results based on observations of ~100 Swift/BAT-selected Type-2 Seyferts surveyed in the first three years of NuSTAR operation. This large sample forms an atlas of the highest quality hard X-ray spectra available to date. Assuming a range of hard X-ray spectral models, phenomenological as well as physically motivated, we constrain the main spectral parameters for each source individually and test the applicability of the models on a large sample for the first time. This analysis allows us to determine distributions of the main spectral parameters related to the torus, such as the absorption column, reflection strength, and iron line equivalent width, in a well-defined population of nearby obscured AGN. More advanced models for the AGN torus allow us to investigate differences between various subsamples and interpret them within the unified model paradigm. We will discuss the implications for the structure of the torus in the local population of Type-2 Seyferts and present a comprehensive comparison of constraints derived from X-ray data and constraints from observations at other wavelengths for a relatively large sample.

  2. The Starburst-AGN connection: quenching the fire and feeding the monster

    NASA Astrophysics Data System (ADS)

    Melnick, Jorge; Telles, Eduardo; De Propris, Roberto; Chu, Zhang-Hu

    2015-10-01

    The merger of two spiral galaxies is believed to be one of the main channels for the production of elliptical and early-type galaxies. In the process, the system becomes an (ultra) luminous infrared galaxy, or (U)LIRG, that morphs to a quasar, to a K+A galaxy, and finally to an early-type galaxy. The time scales for this metamorphosis are only loosely constrained by observations. In particular, the K+A phase should follow immediately after the quasi stellar object (QSO) phase during which the dust and gas remaining from the (U)LIRG phase are expelled by the active galactic nucleus (AGN). An intermediate class of QSOs with K+A spectral signatures, the post-starburst QSOs (PSQ), may represent the transitional phase between QSOs and K+As. We have compiled a sample of 72 bona fide z < 0.5 PSQ from the SDSS DR7 QSO catalogue. We find the intermediate age populations in this sample to be on average significantly weaker and metal poorer than their putative descendants, the K+A galaxies. The typical spectral energy distribution of PSQ is well fitted by three components: starlight; an obscured power-law; and a hot dust component required to reproduce the mid-IR fluxes. From the slope and bolometric luminosity of the power-law component we estimate typical masses and accretion rates of the AGN, but we find little evidence of powerful radio-loud or strong X-ray emitters in our sample. This may indicate that the power-law component originates in a nuclear starburst rather than in an AGN, as expected if the bulk of their young stars are still being formed, or that the AGN is still heavily enshrouded in dust and gas. We find that both alternatives are problematic and that more and better optical, X-ray, and mm-wave observations are needed to elucidate the evolutionary history of PSQ.

  3. X-ray Signatures of Accretion in AGNs with Intermediate-mass Black Holes

    NASA Astrophysics Data System (ADS)

    Ho, Luis

    2009-09-01

    Supermassive (10^6-10^9 solar mass) black holes (BHs) are closely linked with the evolution of early-type galaxies. Our group has discovered a new class of AGNs with intermediate-mass (10^4-10^6 solar mass) BHs in late-type galaxies. These objects offer important clues to the nature of the seeds of quasars, and their mergers may produce significant gravity waves. We have started to systematically study their multiwavelength properties. A pilot Chandra program revealed that they are unusually X-ray bright, possibly because their low BH masses and high accretion rates sustain a slim accretion disk. We propose to extend and confirm our preliminary results by performing a comprehensive survey of the X-ray properties of a larger sample of this new class of AGNs.

  4. X-Ray Spectral Studies of AGN with the ASCA Satellite

    NASA Technical Reports Server (NTRS)

    Urry, C. Megan

    1999-01-01

    This project involved the interpretation of Advanced Satellite for Cosmology and Astrophysics (ASCA) observations of Active Galactic Nuclei (AGN), with emphasis on four different aspects of the AGN phenomenon: (1) Absorption by hot gas in blazars: This anomalous absorption was detected in several objects, notably the BL Lacertae (BL Lac) object 1426+428. (2) Separation of blazar and Seyfert components in superluminal radio galaxies and quasars: Both components were found in the radio galaxies samples, but with no clear trend in which dominates. (3) Detection of high energy Compton components in blazars: Both BL Lacs and quasars show hard X-ray spectra that represent the onset of the Compton-scattered gamma-ray component. (4) Correlation of X- and gamma-ray emission in blazars: Several multiwavelength monitoring campaigns showed a correlation between X- and gamma-rays in blazars.

  5. Assessing AGN feedback models with c iii* measurement and photoionization modeling

    NASA Astrophysics Data System (ADS)

    McGinnis, Daniel J.

    2013-12-01

    Mass outflows in active galactic nuclei (AGN) have been hypothesized to represent a feedback mechanism through which black hole growth and galaxy formation are linked. In order to assess this claim, typical outflow kinetic luminosities must be compared to calculated minimum values that are needed to produce feedback relevance. We have developed a method for placing lower limits on the kinetic luminosity by combining photoionization modeling with column density measurements of a select few ionic species, including C III* 1175 as a measure of gas density. This method is applied to sample AGNs representative of those observed with the Sloan Digital Sky Survey (SDSS) and the Cosmic Origins Spectrograph (HST/COS). We find that although measured kinetic luminosity lower limits for the quasar SDSS J170322.41+23124.3 and Seyfert galaxy Akn 564 are several orders of magnitude less than that required for feedback relevance, our method can be drastically improved with increased signal to noise ratios.

  6. Early Results from Swift AGN and Cluster Survey

    NASA Astrophysics Data System (ADS)

    Dai, Xinyu; Griffin, Rhiannon; Nugent, Jenna; Kochanek, Christopher S.; Bregman, Joel N.

    2016-04-01

    The Swift AGN and Cluster Survey (SACS) uses 125 deg^2 of Swift X-ray Telescope serendipitous fields with variable depths surrounding gamma-ray bursts to provide a medium depth (4 × 10^-15 erg cm^-2 s^-1) and area survey filling the gap between deep, narrow Chandra/XMM-Newton surveys and wide, shallow ROSAT surveys. Here, we present the first two papers in a series of publications for SACS. In the first paper, we introduce our method and catalog of 22,563 point sources and 442 extended sources. SACS provides excellent constraints on the AGN and cluster number counts at the bright end with negligible uncertainties due to cosmic variance, and these constraints are consistent with previous measurements. The depth and areal coverage of SACS is well suited for galaxy cluster surveys outside the local universe, reaching z > 1 for massive clusters. In the second paper, we use SDSS DR8 data to study the 203 extended SACS sources that are located within the SDSS footprint. We search for galaxy over-densities in 3-D space using SDSS galaxies and their photometric redshifts near the Swift galaxy cluster candidates. We find 103 Swift clusters with a > 3σ over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmations as galaxy clusters. We present a series of cluster properties including the redshift, BCG magnitude, BCG-to-X-ray center offset, optical richness, X-ray luminosity and red sequences. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z ≤ 0.3 and 80% complete for z ≤ 0.4, consistent with the survey depth of SDSS. These analysis results suggest that our Swift cluster selection algorithm presented in our first paper has yielded a statistically well-defined cluster sample for further studying cluster evolution and cosmology. In the end, we will discuss our ongoing optical identification of z>0.5 cluster

  7. The Effect of Ag and Ag+N Ion Implantation on Cell Attachment Properties

    SciTech Connect

    Urkac, Emel Sokullu; Oztarhan, Ahmet; Gurhan, Ismet Deliloglu; Iz, Sultan Gulce; Tihminlioglu, Funda; Oks, Efim; Nikolaev, Alexey; Ila, Daryush

    2009-03-10

    Implanted biomedical prosthetic devices are intended to perform safely, reliably and effectively in the human body thus the materials used for orthopedic devices should have good biocompatibility. Ultra High Molecular Weight Poly Ethylene (UHMWPE) has been commonly used for total hip joint replacement because of its very good properties. In this work, UHMWPE samples were Ag and Ag+N ion implanted by using the Metal-Vapor Vacuum Arc (MEVVA) ion implantation technique. Samples were implanted with a fluency of 1017 ion/cm2 and extraction voltage of 30 kV. Rutherford Backscattering Spectrometry (RBS) was used for surface studies. RBS showed the presence of Ag and N on the surface. Cell attachment properties investigated with model cell lines (L929 mouse fibroblasts) to demonstrate that the effect of Ag and Ag+N ion implantation can favorably influence the surface of UHMWPE for biomedical applications. Scanning electron microscopy (SEM) was used to demonstrate the cell attachment on the surface. Study has shown that Ag+N ion implantation represents more effective cell attachment properties on the UHMWPE surfaces.

  8. The Effect of Ag and Ag+N Ion Implantation on Cell Attachment Properties

    NASA Astrophysics Data System (ADS)

    Urkac, Emel Sokullu; Oztarhan, Ahmet; Tihminlioglu, Funda; Gurhan, Ismet Deliloglu; Iz, Sultan Gulce; Oks, Efim; Nikolaev, Alexey; Ila, Daryush

    2009-03-01

    Implanted biomedical prosthetic devices are intended to perform safely, reliably and effectively in the human body thus the materials used for orthopedic devices should have good biocompatibility. Ultra High Molecular Weight Poly Ethylene (UHMWPE) has been commonly used for total hip joint replacement because of its very good properties. In this work, UHMWPE samples were Ag and Ag+N ion implanted by using the Metal-Vapor Vacuum Arc (MEVVA) ion implantation technique. Samples were implanted with a fluency of 1017 ion/cm2 and extraction voltage of 30 kV. Rutherford Backscattering Spectrometry (RBS) was used for surface studies. RBS showed the presence of Ag and N on the surface. Cell attachment properties investigated with model cell lines (L929 mouse fibroblasts) to demonstrate that the effect of Ag and Ag+N ion implantation can favorably influence the surface of UHMWPE for biomedical applications. Scanning electron microscopy (SEM) was used to demonstrate the cell attachment on the surface. Study has shown that Ag+N ion implantation represents more effective cell attachment properties on the UHMWPE surfaces.

  9. The Keck OSIRIS Nearby AGN Survey: Tracing Inflow within the Central 200 pc of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Hicks, Erin K. S.; Müller-Sánchez, Francisco; Malkan, Matthew A.; Yu, Po-Chieh

    2016-08-01

    In an effort to identify the fundamental processes driving feeding and feedback in AGN we turn to local Seyfert galaxies and rely on a multi-wavelength approach. With the integral field unit OSIRIS and adaptive optics we characterize the nuclear stars and gas down to scales of 5-30 parsecs in a sample of 40 Seyfert galaxies with the Keck OSIRIS Nearby AGN (KONA) survey. The complex gas kinematics in these near-IR data are interpreted using an integrative approach through comparison with data available at a range of wavelengths. We present first results from the survey with a focus on work aimed at constraining the mechanism(s) driving inflow of material within the central 200 pc. Particularly useful in the identification of inflow mechanisms (e.g. nuclear spiral, external accretion) is spatial correlation of the molecular gas distribution and kinematics with dust features revealed in HST imaging (optical and near-IR). Also informative is comparison with X-ray emission to identify locations likely influenced by interactions with outflows. The stellar kinematics in the sample galaxies (traced by CO bandheads at 2.3 microns) indicate a stellar population within the central few 100 parsecs in circular rotation, and in the majority of the galaxies the molecular gas (traced by H2 emission at 2.1218 microns) is found to have a rotating component co-spatial with the stellar disk. A significant fraction of the galaxies also exhibit kinematic signatures of inflow superimposed on this disk rotation, with inflow driven by secular and non-secular processes identified. We explore statistical trends of the nuclear stellar and molecular gas properties, including primary fueling mechanism, with Seyfert type, AGN luminosity, and host environment with the goal of disentangling which properties are fundamental to the nature of the AGN.

  10. The Role of Outburst Shock Heating in AGN Feedback

    NASA Astrophysics Data System (ADS)

    Randall, Scott W.; Nulsen, Paul; Jones, Christine; Forman, William R.

    2016-04-01

    One of the major discoveries of modern X-ray observatories is that central AGN in galaxies, groups, and clusters can regulate cooling in the diffuse X-ray emitting gas. This connection is demonstrated by the presence of large cavities in the diffuse gas, usually filled with radio-emitting plasma, that have been evacuated by jets from the AGN. This AGN feedback has important consequences for star formation, galaxy evolution, super-massive black hole growth, galaxy/black hole scaling relations, cluster scaling relations, and the growth of structure. Although it has generally been found that the kinetic output of central AGN scales with the gas cooling rate and is energetic enough to offset cooling, the details of how and where this energy is transferred to heat the gas are poorly understood. I will discuss the role of weak AGN outburst shocks in heating the diffuse gas, and present some results from a very deep (650 ks) Chandra observation of the galaxy group NGC 5813. With three three pairs of collinear cavities, each pair associated with an elliptical AGN outburst shock, NGC 5813 is uniquely well-suited to studying the outburst history of the AGN and the mean shock heating rate.

  11. Compton Thick AGN in the XMM-COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Perna, M.; Delvecchio, I.; Berta, S.; Brusa, M.; Gruppioni, C.; Comastri, A.

    2016-06-01

    I will present results we published in two recent papers (Lanzuisi et al. 2015, A&A 573A 137, Lanzuisi et al. 2015, A≈A 578A 120) on the properties of X-ray selected Compton Thick (CT, NH>10^{24} cm^{-2}) AGN, in the XMM-COSMOS survey. We exploited the rich multi-wavelength dataset available in this field, to show that CT AGN tend to harbor smaller, rapidly growing SMBH with respect to unobscured AGN, and have a higher chance of being hosted by star-forming, merging and post-merger systems. We also demonstrated the detectability of even more heavily obscured AGN (NH>10^{25} cm^{-2}), thanks to a truly multi-wavelength approach in the same field, and to the unrivaled XMM sensitivity. The extreme source detected in this way shows strong evidences of ongoing powerful AGN feedback, detected as blue-shifted wings of high ionization optical emission lines such as [NeV] and [FeVII], as well as of the [OIII] emission line. The results obtained from these works point toward a scenario in which highly obscured AGN occupy a peculiar place in the galaxy-AGN co-evolution process, in which both the host and the SMBH rapidly evolve toward the local relations.

  12. Structure Function Analysis of AGN Variability using Kepler

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.

    2014-06-01

    We study the variability properties of AGN light-curves observed by the Kepler satellite. AGN optical fluxes are known to exhibit stochastic variations on time-scales of hours, days, months and years. Previous efforts to characterize the stochastic nature of this variability have been hampered by the lack of high-precision space-based measurements of AGN fluxes with regular cadence. Kepler provides light-curves with a S/N ratio of 10-5 for 87 AGN observed over a period of ~ 3 years with a cadence of once every 30 minutes allowing for a detailed examination of the variability process. We probe AGN variability using the Structure Functions of the light-curves of the Kepler AGN. Monte-Carlo simulations of the structure function are used to fit the observed light-curve to models for the Power Spectral Density. We test various models for the form of the PSD including the damped random walk and the powered exponential models. We show that on the shorter time-scales probed by Kepler data, the damped random walk model fails to adequately characterize AGN variability. We find that the PSD may be better modelled by combination of a steep power law of the form 1/f3 on shorter time-scales, and a more shallow power law of the form 1/f2 on the longer time-scales traditionally probed by ground-based variability studies.

  13. Exploring AGN-starburst coexistence in galaxies at z ˜ 0.8 using the [O III]4959+5007/[O III]4363 line ratio

    NASA Astrophysics Data System (ADS)

    Contini, M.

    2016-09-01

    Using detailed modelling, we analyse the spectra observed from the sample galaxies at z ˜ 0.8 presented by Ly et al., constraining the models by the [O III]5007+4959/[O III]4363 line ratios. Composite models (shock + photoionization) are adopted. Shock velocities ≥100 km s-1 and pre-shock densities n0 ˜ 200 cm-3 characterize the gas surrounding the starburst (SB), while n0 are higher by a factor of 1.5-10 in the AGN emitting gas. SB effective temperatures are similar to those of quiescent galaxies (T* ˜ 4-7 × 104 K). Cloud geometrical thicknesses in the SB are ≤1016 cm, indicating major fragmentation, while in AGN they reach >10 pc. O/H are about solar for all the objects, except for a few AGN clouds with O/H = 0.3-0.5 solar. SB models reproduce most of the data within the observational errors. About half of the objects' spectra are well fitted by an accreting AGN. Some galaxies show multiple radiation sources, such as SB + AGN, or a double AGN.

  14. Tracing the incidence of X-ray AGN and their distribution of accretion rates across the galaxy population

    NASA Astrophysics Data System (ADS)

    Aird, James; Coil, Alison; Georgakakis, Antonis; Nandra, Kirpal

    2016-08-01

    X-ray selection provides a powerful method of identifying AGN across a variety of host galaxies and with a wide range of accretion rates. However, careful consideration of the underlying selection biases are vital to reveal the true underlying distribution of accretion rates and determine how the incidence of AGN is related to the properties of the galaxies that host them. I will present new measurements of the distribution of specific accretion rates (scaled relative to the total host galaxy mass, roughly tracing the Eddington ratio) within both star-forming and quiescent galaxy populations. We combine near-infrared selected samples of galaxies from the CANDELS/3D-HST and UltraVISTA surveys with deep Chandra X-ray data and use an advanced Bayesian technique to constrain the underlying distribution of specific accretion rates as a function of stellar mass and redshift. Our results reveal a broad distribution of accretion rates (reflecting long-term variability in the level of AGN fuelling) in both galaxy types. The probability of a star-forming galaxy hosting an AGN (above a fixed specific accretion rate) has a strong stellar mass dependence - revealing an intrinsically higher incidence of AGN in massive star-forming galaxies - and undergoes a stellar-mass-dependent evolution with redshift. The probability of a quiescent galaxy hosting an AGN is generally lower but does not depend on stellar mass and evolves differently with redshift. These results provide vital insights into the relationship between the growth of black hole and the physical properties of their host galaxies.

  15. Ultra-Fast Outflows in Radio-Loud AGN: New Constraints on Jet-Disk Connection

    NASA Astrophysics Data System (ADS)

    Sambruna, Rita

    of the broad-band X-ray spectra of radio-loud AGN for comparison to radio-quiet, addressing the origin of the division between the two classes. In addition, the upcoming Astro-H mission will greatly benefit from the outcomes of this project, which will provide templates for realistic simulations to define the scientific requirements of the calorimeter, and a list of targets to design a sample for the core AGN projects of the team.

  16. Radio AGN in the local universe: unification, triggering and evolution

    NASA Astrophysics Data System (ADS)

    Tadhunter, Clive

    2016-06-01

    Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_{1.4 GHz} > 10^{24} W Hz^{-1}) are a key sub-class of the overall AGN population. Recently their study has benefitted dramatically from the availability of high-quality data covering the X-ray to far-IR wavelength range obtained with the current generation of ground- and space-based telescope facilities. Reflecting this progress, here I review our current state of understanding of the population of radio AGN at low and intermediate redshifts (z < 0.7), concentrating on their nuclear AGN and host galaxy properties, and covering three interlocking themes: the classification of radio AGN and its interpretation; the triggering and fuelling of the jet and AGN activity; and the evolution of the host galaxies. I show that much of the observed diversity in the AGN properties of radio AGN can be explained in terms of a combination of orientation/anisotropy, mass accretion rate, and variability effects. The detailed morphologies of the host galaxies are consistent with the triggering of strong-line radio galaxies (SLRG) in galaxy mergers. However, the star formation properties and cool ISM contents suggest that the triggering mergers are relatively minor in terms of their gas masses in most cases, and would not lead to major growth of the supermassive black holes and stellar bulges; therefore, apart from a minority (<20 %) that show evidence for higher star formation rates and more massive cool ISM reservoirs, the SLRG represent late-time re-triggering of activity in mature giant elliptical galaxies. In contrast, the host and environmental properties of weak-line radio galaxies (WLRG) with Fanaroff-Riley class I radio morphologies are consistent with more gradual fuelling of the activity via gas accretion at low rates onto the supermassive black holes.

  17. Supernovae and AGN Driven Galactic Outflows

    NASA Astrophysics Data System (ADS)

    Sharma, Mahavir; Nath, Biman B.

    2013-01-01

    We present analytical solutions for winds from galaxies with a Navarro-Frank-White (NFW) dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae (SNe), as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (1) v_\\star ˜ (\\dot{E} / 2 \\dot{M})^{1/2} describes the effect of starburst activity, with \\dot{E} and \\dot{M} as energy and mass injection rate in a central region of radius R; (2) v • ~ (GM •/2R)1/2 for the effect of a central black hole of mass M • on gas at distance R; and (3) v_{s} =(GM_h / 2 {C}r_s)^{1/2}, which is closely related to the circular speed (vc ) for an NFW halo, where rs is the halo scale radius and {C} is a function of the halo concentration parameter. Our generalized formalism, in which we treat both energy and momentum injection from starbursts and radiation from the central active galactic nucleus (AGN), allows us to estimate the wind terminal speed to be (4v 2 sstarf + 6(Γ - 1)v • 2 - 4v 2 s )1/2, where Γ is the ratio of force due to radiation pressure to gravity of the central black hole. Our dynamical model also predicts the following: (1) winds from quiescent star-forming galaxies cannot escape from 1011.5 M ⊙ <= Mh <= 1012.5 M ⊙ galaxies; (2) circumgalactic gas at large distances from galaxies should be present for galaxies in this mass range; (3) for an escaping wind, the wind speed in low- to intermediate-mass galaxies is ~400-1000 km s-1, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds >~ 1000 km s-1. We also find that the ratio [2v 2 sstarf - (1 - Γ)v • 2]/v 2 c dictates the amount of gas lost through winds. Used in conjunction with an appropriate relation between M • and Mh and an appropriate opacity of dust grains in infrared (K band), this ratio has the attractive property of being minimum at a certain halo

  18. Using VO tools to investigate distant radio starbursts hosting obscured AGN in the HDF(N) region

    NASA Astrophysics Data System (ADS)

    Richards, A. M. S.; Muxlow, T. W. B.; Beswick, R.; Allen, M. G.; Benson, K.; Dickson, R. C.; Garrett, M. A.; Garrington, S. T.; Gonzalez-Solarez, E.; Harrison, P. A.; Holloway, A. J.; Kettenis, M. M.; Laing, R. A.; Richards, E. A.; Thrall, H.; van Langevelde, H. J.; Walton, N. A.; Wilkinson, P. N.; Winstanley, N.

    2007-09-01

    Context: A 10-arcmin region around the Hubble Deep Field (North) contains 92 radio sources brighter than 40 μJy which are well-resolved by MERLIN+VLA at 0.2arcsec-2' resolution (average size ~1"). 55 of these have Chandra X-ray counterparts in the 2-Ms CDF(N) field including at least 17 with a hard X-ray photon index and high luminosity characteristic of a type-II (obscured) AGN. More than 70% of the radio sources have been classified as starbursts or AGN using radio morphologies, spectral indices and comparisons with optical appearance and rest-frame MIR emission. On this basis, starbursts outnumber radio AGN 3:1. Aims: We investigate the possibility that very luminous radio and X-ray emission originates from different phenomena in the same high-redshift galaxies. Methods: This study extends the Virtual Observatory (VO) methods previously used to identify X-ray-selected obscured type-II AGN, to examine the relationship between radio and X-ray emission. We describe a VO cut-out server for MERLIN+VLA 1.4-GHz radio images in the HDF(N) region. Results: The high-redshift starbursts have typical sizes of 5-10 kpc and star formation rates of ~1000 M⊙ yr-1, an order of magnitude more extended and intense than in the local universe. There is no obvious correlation between radio and X-ray luminosities nor spectral indices at z ⪆ 1.3. About 70% of both the radio-selected AGN and the starburst samples were detected by Chandra. The X-ray luminosity indicates the presence of an AGN in at least half of the 45 cross-matched radio starbursts. Eleven of these are type-II AGN, of which 7 are at z ≥ 1.5. This distribution overlaps closely with the X-ray detected radio sources which were also detected by SCUBA. In contrast, all but one of the AGN-dominated radio sources are at z < 1.5, including the 4 which are also X-ray selected type-II AGN. The stacked 1.4-GHz emission at the positions of radio-faint X-ray sources is correlated with X-ray hardness. Conclusions: Almost all

  19. Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-05-01

    Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ˜0.0003-0.03 pc (˜ 102-104rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ˜0.01 and 1 M⊙ yr-1, corresponding to >rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log? 42.6-44.6 erg s-1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies.

  20. X-ray Evidence for Ultra-Fast Outflows in Local AGNs

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Cappi, M.; Sambruna, R. M.; Reeves, J. N.; Reynolds, C. S.; Braito, V.; Dadina, M.

    2012-08-01

    X-ray evidence for ultra-fast outflows (UFOs) has been recently reported in a number of local AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 Broad-Line Radio Galaxies (BLRGs) observed with XMM-Newton and Suzaku. We detect UFOs in ga 40% of the sources. Their outflow velocities are in the range ˜ 0.03-0.3c, with a mean value of ˜ 0.14c. The ionization is high, in the range logℰ ˜3-6rm erg s-1 cm, and also the associated column densities are large, in the interval ˜ 1022-1024rm cm-2. Overall, these results point to the presence of highly ionized and massive outflowing material in the innermost regions of AGNs. Their variability and location on sub-pc scales favor a direct association with accretion disk winds/outflows. This also suggests that UFOs may potentially play a significant role in the AGN cosmological feedback besides jets, and their study can provide important clues on the connection between accretion disks, winds, and jets.

  1. ALMA resolves extended star formation in high-z AGN host galaxies

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Simpson, J. M.; Stanley, F.; Alexander, D. M.; Daddi, E.; Mullaney, J. R.; Pannella, M.; Rosario, D. J.; Smail, Ian

    2016-03-01

    We present high-resolution (0.3 arcsec) Atacama Large Millimeter Array (ALMA) 870 μm imaging of five z ≈ 1.5-4.5 X-ray detected AGN (with luminosities of L2-8keV > 1042 erg s-1). These data provide a ≳20 times improvement in spatial resolution over single-dish rest-frame far-infrared (FIR) measurements. The sub-millimetre emission is extended on scales of FWHM ≈ 0.2 arcsec-0.5 arcsec, corresponding to physical sizes of 1-3 kpc (median value of 1.8 kpc). These sizes are comparable to the majority of z=1-5 sub-millimetre galaxies (SMGs) with equivalent ALMA measurements. In combination with spectral energy distribution analyses, we attribute this rest-frame FIR emission to dust heated by star formation. The implied star-formation rate surface densities are ≈20-200 M⊙ yr-1 kpc-2, which are consistent with SMGs of comparable FIR luminosities (i.e. LIR ≈ [1-5] × 1012 L⊙). Although limited by a small sample of AGN, which all have high-FIR luminosities, our study suggests that the kpc-scale spatial distribution and surface density of star formation in high-redshift star-forming galaxies is the same irrespective of the presence of X-ray detected AGN.

  2. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs: III - Location and Energetics

    NASA Technical Reports Server (NTRS)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-01-01

    Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval approx.0.0003-0.03pc (approx.10(exp 2)-10(exp 4)tau(sub s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between approx.0.01- 1 Stellar Mass/y, corresponding to approx. or >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are logE(sub K) approx. or = 42.6-44.6 erg/s. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN r.osmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies .

  3. X-ray AGN in the XMM-LSS galaxy clusters: no evidence of AGN suppression

    NASA Astrophysics Data System (ADS)

    Koulouridis, E.; Plionis, M.; Melnyk, O.; Elyiv, A.; Georgantopoulos, I.; Clerc, N.; Surdej, J.; Chiappetti, L.; Pierre, M.

    2014-07-01

    We present a study of the overdensity of X-ray-selected active galactic nuclei (AGN) in 33 galaxy clusters in the XMM-LSS field (The XMM-Newton Large Scale Structure Survey), up to redshift z = 1.05 and further divided into a lower (0.14 ≤ z ≤ 0.35) and a higher redshift (0.43 ≤ z ≤ 1.05) subsample. Previous studies have shown that the presence of X-ray-selected AGN in rich galaxy clusters is suppressed, since their number is significantly lower than what is expected from the high galaxy overdensities in the area. In the current study we have investigated the occurrence of X-ray-selected AGN in low (⟨ Lx,bol ⟩ = 2.7 × 1043 erg/s) and moderate (⟨ Lx,bol ⟩ = 2.4 × 1044 erg/s) X-ray luminosity galaxy clusters in an attempt to trace back the relation between high-density environments and nuclear activity. Owing to the wide contiguous XMM-LSS survey area, we were able to extend the study to the cluster outskirts. We therefore determined the projected overdensity of X-ray point-like sources around each cluster out to 6r500 radius, within δr500 = 1 annulus, with respect to the field expectations based on the X-ray source log N - log S of the XMM-LSS field. To provide robust statistical results we also conducted a consistent stacking analysis separately for the two z ranges. We investigated whether the observed X-ray overdensities are to be expected thanks to the obvious enhancement of galaxy numbers in the cluster environment by also estimating the corresponding optical galaxy overdensities, and we assessed the possible enhancement or suppression of AGN activity in clusters. We find a positive X-ray projected overdensity in both redshift ranges at the first radial bins, which however has the same amplitude as that of optical galaxies. Therefore, no suppression (or enhancement) of X-ray AGN activity with respect to the field is found, in sharp contrast to previous results based on rich galaxy clusters, implying that the mechanisms responsible for the

  4. AGN-selected clusters as revealed by weak lensing

    NASA Technical Reports Server (NTRS)

    Wold, M.; Lacy, M.; Dahle, H.; Lilje, P. B.; Ridgway, S. E.

    2002-01-01

    We discuss the results in light of the cooling flow and the merger/interaction scenarios for triggering and fuelling AGN in clusters, but find that the data do not point unambiguously to neither of the two.

  5. Broad Band Properties of the BAT Selected AGN

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard; Winter, Lisa; Tueller, jack

    2008-01-01

    We will present the x-ray spectral properties of approximately 150 Burst Alert Telescope (BAT) selected active galactic nuclei (AGN) focusing on the issues of spectral complexity, x-ray absorption and its distribution and that contribution of sources to the x-ray background. If time permits we will also present the nature of the host galaxies of the AGN and their relationship to merger candidates.

  6. GOODS-Herschel: ultra-deep XMM-Newton observations reveal AGN/star-formation connection

    NASA Astrophysics Data System (ADS)

    Rovilos, E.; Comastri, A.; Gilli, R.; Georgantopoulos, I.; Ranalli, P.; Vignali, C.; Lusso, E.; Cappelluti, N.; Zamorani, G.; Elbaz, D.; Dickinson, M.; Hwang, H. S.; Charmandaris, V.; Ivison, R. J.; Merloni, A.; Daddi, E.; Carrera, F. J.; Brandt, W. N.; Mullaney, J. R.; Scott, D.; Alexander, D. M.; Del Moro, A.; Morrison, G.; Murphy, E. J.; Altieri, B.; Aussel, H.; Dannerbauer, H.; Kartaltepe, J.; Leiton, R.; Magdis, G.; Magnelli, B.; Popesso, P.; Valtchanov, I.

    2012-10-01

    Models of galaxy evolution assume some connection between the AGN and star formation activity in galaxies. We use the multi-wavelength information of the CDFS to assess this issue. We select the AGNs from the 3 Ms XMM-Newton survey and measure the star-formation rates of their hosts using data that probe rest-frame wavelengths longward of 20 μm, predominantly from deep 100 μm and 160 μm Herschel observations, but also from Spitzer-MIPS-70 μm. Star-formation rates are obtained from spectral energy distribution fits, identifying and subtracting an AGN component. Our sample consists of sources in the z ≈ 0.5-4 redshift range, with star-formation rates SFR ≈ 101-103 M⊙ yr-1 and stellar masses M⋆ ≈ 1010-1011.5 M⊙. We divide the star-formation rates by the stellar masses of the hosts to derive specific star-formation rates (sSFR) and find evidence for a positive correlation between the AGN activity (proxied by the X-ray luminosity) and the sSFR for themost active systems with X-ray luminosities exceeding Lx ≃ 1043 erg s-1 and redshifts z ≳ 1. We do not find evidence for such a correlation for lower luminosity systems or those at lower redshifts, consistent with previous studies. We do not find any correlation between the SFR (or the sSFR) and the X-ray absorption derived from high-quality XMM-Newton spectra either, showing that the absorption is likely to be linked to the nuclear region rather than the host, while the star-formation is not nuclear. Comparing the sSFR of the hosts to the characteristic sSFR of star-forming galaxies at the same redshift (the so-called "main sequence") we find that the AGNs reside mostly in main-sequence and starburst hosts, reflecting the AGN-sSFR connection; however the infrared selection might bias this result. Limiting our analysis to the highest X-ray luminosity AGNs (X-ray QSOs with Lx > 1044 erg s-1), we find that the highest-redshift QSOs (with z ≳ 2) reside predominantly in starburst hosts, with an average s

  7. On the physical origin of AGN outflow driving mechanisms

    NASA Astrophysics Data System (ADS)

    Ishibashi, Wako

    2016-07-01

    Super-massive black holes in active galactic nuclei (AGN) respond to the accretion process by feeding back energy and momentum into the surrounding environment. Galaxy-scale outflows are thought to provide the physical link connecting the small scales of the central black hole to the large scales of the host galaxy. Such powerful outflows are now starting to be commonly observed, and have been considered as a proof of AGN feedback in action. However, the physical origin of the mechanism driving the observed outflows is still unclear, and whether it is due to energy-driving or radiation-driving is a source of much debate in the literature. We consider AGN feedback driven by radiation pressure on dust, and show that AGN radiative feedback is capable of driving powerful outflows on galactic scales. In particular, we can obtain outflowing shells with high velocity and large momentum flux, by properly taking into account the effects of radiation trapping. Alternatively, the observed outflow characteristics may be significantly biased by AGN variability. I will discuss the resulting implications in the global context of black hole accretion-AGN feedback coupling.

  8. YOUNG AGN OUTBURST RUNNING OVER OLDER X-RAY CAVITIES

    SciTech Connect

    Bogdán, Ákos; Van Weeren, Reinout J.; Kraft, Ralph P.; Forman, William R.; Randall, Scott; Jones, Christine; Giacintucci, Simona; Churazov, Eugene; O'Dea, Christopher P.; Baum, Stefi A.; Noell-Storr, Jacob

    2014-02-20

    Although the energetic feedback from active galactic nuclei (AGNs) is believed to have a profound effect on the evolution of galaxies and clusters of galaxies, details of AGN heating remain elusive. Here, we study NGC 193—a nearby lenticular galaxy—based on X-ray (Chandra) and radio (Very Large Array and Giant Meter-wave Radio Telescope) observations. These data reveal the complex AGN outburst history of the galaxy: we detect a pair of inner X-ray cavities, an outer X-ray cavity, a shock front, and radio lobes extending beyond the inner cavities. We suggest that the inner cavities were produced ∼78 Myr ago by a weaker AGN outburst, while the outer cavity, the radio lobes, and the shock front are due to a younger (13-26 Myr) and 4-8 times more powerful outburst. Combining this with the observed morphology of NGC 193, we conclude that NGC 193 likely represents the first example of a second, more powerful, AGN outburst overrunning an older, weaker outburst. These results help us to understand how the outburst energy is dissipated uniformly in the core of galaxies, and therefore may play a crucial role in resolving how AGN outbursts suppress the formation of large cooling flows at cluster centers.

  9. Young AGN Outburst Running over Older X-Ray Cavities

    NASA Astrophysics Data System (ADS)

    Bogdan, Akos; van Weeren, Reinout Johannes; Kraft, Ralph; Forman, William; Scott, Randall; Giacintucci, Simona; Churazov, Eugene; O'Dea, Christopher; Baum, Stefi; Noell-Storr, Jacob; Jones, Christine

    2015-08-01

    Although the energetic feedback from active galactic nuclei (AGNs) is believed to have a profound effect on the evolution of galaxies and clusters of galaxies, details of AGN heating remain elusive. Here, we study NGC 193 -- a nearby lenticular galaxy in a group -- based on X-ray and radio observations. These data reveal the complex AGN outburst history of the galaxy: we detect a pair of inner X-ray cavities, an outer X-ray cavity, a shock front, and radio lobes extending beyond the inner cavities. We suggest that the inner cavities were produced about 78 Myr ago by a weaker AGN outburst, while the outer cavity, the radio lobes, and the shock front are due to a younger (13-26 Myr) and 4-8 times more powerful outburst. Combining this with the observed morphology of NGC 193, we conclude that NGC 193 likely represents the first example of a second, more powerful, AGN outburst overrunning an older, weaker outburst. These results help us to understand how the outburst energy is dissipated uniformly in the core of galaxies, and therefore may play a crucial role in resolving how AGN outbursts suppress the formation of large cooling flows at cluster centers.

  10. Compton-thick AGN in the 70-month Swift-BAT All-Sky Hard X-ray Survey: A Bayesian approach

    NASA Astrophysics Data System (ADS)

    Akylas, A.; Georgantopoulos, I.; Ranalli, P.; Gkiokas, E.; Corral, A.; Lanzuisi, G.

    2016-10-01

    The 70-month Swift-BAT catalogue provides a sensitive view of the extragalactic X-ray sky at hard energies (>10 keV) containing about 800 active galactic nuclei (AGN). We explore its content in heavily obscured, Compton-thick AGN by combining the BAT (14-195 keV) with the lower energy XRT (0.3-10 keV) data. We apply a Bayesian methodology using Markov chains to estimate the exact probability distribution of the column density for each source. We find 53 possible Compton-thick sources (probability range 3-100%) translating to a ~7% fraction of the AGN in our sample. We derive the first parametric luminosity function of Compton-thick AGN. The unabsorbed luminosity function can be represented by a double power law with a break at L⋆ ~ 2 × 1042erg s-1 in the 20-40 keV band. The Compton-thick AGN contribute ~17% of the total AGN emissivity. We derive an accurate Compton-thick number count distribution taking into account the exact probability of a source being Compton-thick and the flux uncertainties. This number count distribution is critical for the calibration of the X-ray background synthesis models, i.e. for constraining the intrinsic fraction of Compton-thick AGN. We find that the number counts distribution in the 14-195 keV band agrees well with our models which adopt a low intrinsic fraction of Compton-thick AGN (~ 12%) among the total AGN population and a reflected emission of ~ 5%. In the extreme case of zero reflection, the number counts can be modelled with a fraction of at most 30% Compton-thick AGN of the total AGN population and no reflection. Moreover, we compare our X-ray background synthesis models with the number counts in the softer 2-10 keV band. This band is more sensitive to the reflected component and thus helps us to break the degeneracy between the fraction of Compton-thick AGN and the reflection emission. The number counts in the 2-10 keV band are well above the models which assume a 30% Compton-thick AGN fraction and zero reflection, while

  11. Multi-epoch Spectroscopy of Dwarf Galaxies with AGN Signatures: Identifying Sources with Persistent Broad Hα Emission

    NASA Astrophysics Data System (ADS)

    Baldassare, Vivienne F.; Reines, Amy E.; Gallo, Elena; Greene, Jenny E.; Graur, Or; Geha, Marla; Hainline, Kevin; Carroll, Christopher M.; Hickox, Ryan C.

    2016-09-01

    We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accreting black holes (BHs) and stellar processes (i.e., supernovae) for 16 galaxies identified as active galactic nucleus (AGN) candidates by Reines et al (2013). Our study is primarily focused on those objects with narrow emission line ratios dominated by star formation, for which the origin of the broad Hα emission was unclear. Based on follow-up spectroscopy, we find that the broad Hα emission has faded or was ambiguous for all of the star-forming objects (14/16), over baselines ranging from 5-14 years, suggesting a transient stellar process was responsible for the broad emission in previous Sloan Digital Sky Survey observations. For the two objects in our follow-up sample with narrow-line AGN signatures (RGG 9 and RGG 119), we find persistent broad Hα emission consistent with an AGN origin. Additionally, we use high spectral resolution observations to measure stellar velocity dispersions for 15 objects in the Reines et al. (2013) sample, all with narrow-line ratios indicating the presence of an AGN. Stellar masses range from ˜ 5× {10}8 to 3× {10}9 M ⊙, and we measure {σ }* in the range of 28{--}71 {km} {{{s}}}-1. These {σ }* correspond to some of the lowest-mass galaxies with optical signatures of AGN activity. We show that RGG 119, the one object that has both a measured {σ }* and persistent broad Hα emission, falls near the extrapolation of the {\\text{}}{M}{BH}-{σ }\\star relation to the low-mass end.

  12. Investigating AGN Variability Using Combined Multi-Quarter Kepler Data

    NASA Astrophysics Data System (ADS)

    Revalski, Mitchell; Nowak, D.; Wiita, P. J.; Wehrle, A. E.; Unwin, S. C.

    2014-01-01

    The study of long and short term variability in active galactic nuclei (AGN) yields deeper insight into the physical nature of their emissions from the accretion disk around, and relativistic jets powered by, a galaxy’s central super-massive black hole. We have now obtained a total of eleven quarters of Kepler data on four radio-loud AGN. Our prior work involved calculating power spectral densities (PSDs) on these data both with and without corrections for various instrumental artifacts. We now focus on combining these data sets into one continuous set for each object which spans approximately 2.5 years at a 30 minute sampling rate with >98% duty cycle. The process of stringing together these data is complicated by the quarterly rolls the Kepler space satellite telescope conducts, which causes each target to fall on a different CCD four times per year. We attempt to overcome this problem with a scaling procedure that maintains the original percentage of variations and scales all eleven quarters to the overall average. We calculate PSDs on these stitched light curves both with and without various end-matching techniques applied to increase the accuracy of the PSDs. The PSDs computed for the stitched light curves allow us to probe a full decade lower in frequency than our previous work and show comparable slopes to the PSDs calculated for individual quarters, suggesting we are linking the quarters appropriately. Our average PSD slopes are consistent with ground based observations of other quasars, falling approximately between -1.6 and -1.9. In addition, we have used original codes to bin and average individual PSDs to reduce the bias introduced on the slope fitting process induced by the uneven population of points in the PSDs. This allows for a more accurate power law fitting and tends to steepen the overall slope by approximately 0.1 in the majority of cases. We note increased flaring in one of our objects on the order of 15%, with our remaining three objects

  13. Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011

    NASA Astrophysics Data System (ADS)

    H.E.S.S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Bissaldi, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Chalme-Calvet, R.; Chaves, R. C. G.; Cheesebrough, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O.'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Grondin, M.-H.; Grudzińska, M.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Moderski, R.; Mohamed, M.; Moulin, E.; Murach, T.; Naumann, C. L.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rob, L.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorster, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Zabalza, V.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2014-04-01

    Context. About 40% of the observation time of the High Energy Stereoscopic System (H.E.S.S.) is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy (VHE, E > 100 GeV) sources and constraining the physical processes at play in potential emitters. Aims: H.E.S.S. observations of AGN, spanning a period from April 2004 to December 2011, are investigated to constrain their γ-ray fluxes. Only the 47 sources without significant excess detected at the position of the targets are presented. Methods: Upper limits on VHE fluxes of the targets were computed and a search for variability was performed on the nightly time scale. Results: For 41 objects, the flux upper limits we derived are the most constraining reported to date. These constraints at VHE are compared with the flux level expected from extrapolations of Fermi-LAT measurements in the two-year catalog of AGN. The H.E.S.S. upper limits are at least a factor of two lower than the extrapolated Fermi-LAT fluxes for 11 objects. Taking into account the attenuation by the extragalactic background light reduces the tension for all but two of them, suggesting intrinsic curvature in the high-energy spectra of these two AGN. Conclusions: Compilation efforts led by current VHE instruments are of critical importance for target-selection strategies before the advent of the Cherenkov Telescope Array (CTA).

  14. EVERY BCG WITH A STRONG RADIO AGN HAS AN X-RAY COOL CORE: IS THE COOL CORE-NONCOOL CORE DICHOTOMY TOO SIMPLE?

    SciTech Connect

    Sun, M.

    2009-10-20

    The radio active galactic nucleus (AGN) feedback in X-ray cool cores has been proposed as a crucial ingredient in the evolution of baryonic structures. However, it has long been known that strong radio AGNs also exist in 'noncool core' clusters, which brings up the question whether an X-ray cool core is always required for the radio feedback. In this work, we present a systematic analysis of brightest cluster galaxies (BCGs) and strong radio AGNs in 152 groups and clusters from the Chandra archive. All 69 BCGs with radio AGN more luminous than 2 x 10{sup 23} W Hz{sup -1} at 1.4 GHz are found to have X-ray cool cores. BCG cool cores can be divided into two classes: the large cool core (LCC) class and the corona class. Small coronae, easily overlooked at z > 0.1, can trigger strong heating episodes in groups and clusters, long before LCCs are formed. Strong radio outbursts triggered by coronae may destroy embryonic LCCs and thus provide another mechanism to prevent the formation of LCCs. However, it is unclear whether coronae are decoupled from the radio feedback cycles as they have to be largely immune to strong radio outbursts. Our sample study also shows the absence of groups with a luminous cool core while hosting a strong radio AGN, which is not observed in clusters. This points to a greater impact of radio heating on low-mass systems than clusters. Few L {sub 1.4GHz} > 10{sup 24} W Hz{sup -1} radio AGNs (approx16%) host an L {sub 0.5-10keV} > 10{sup 42} erg s{sup -1} X-ray AGN, while above these thresholds, all X-ray AGNs in BCGs are also radio AGNs. As examples of the corona class, we also present detailed analyses of a BCG corona associated with a strong radio AGN (ESO 137-006 in A3627) and one of the faintest coronae known (NGC 4709 in the Centaurus cluster). Our results suggest that the traditional cool core/noncool core dichotomy is too simple. A better alternative is the cool core distribution function, with the enclosed X-ray luminosity or gas mass.

  15. UNDERSTANDING THE AGN-HOST CONNECTION IN BROAD Mg II EMISSION-SELECTED AGN-HOST HYBRID QUASARS

    SciTech Connect

    Wang, J.; Wei, J. Y.

    2009-05-01

    We study the issue of active galactic nucleus (AGN)-host connection in intermediate-z (1.2>z > 0.4) galaxies with hybrid spectra (hybrid QSOs for short). The observed spectra redward of the Balmer limit are dominated by starlight, and the spectra at the blue end by both an AGN continuum and an Mg II broad emission line. This unique property allows us to examine both an AGN and its host galaxy in an individual galaxy simultaneously. First, 15 hybrid QSOs are selected from the Sloan Digital Sky Survey (SDSS) Data Release 6. The spectra are then analyzed in detail for three objects: SDSS J162446.49+461946.7, SDSS J102633.32+103443.8, and SDSS J090036.44+381353.0. Our spectral analysis shows that the current star formation activities are strongly suppressed, and that the latest burst ages range from {approx}400 Myr to 1 Gyr. Based on the Mg II black hole masses, the three hybrid QSOs are consistent with the D{sub n} (4000) - L/L {sub Edd} sequence that was previously established in local AGNs. The three hybrid QSOs are located in the middle range of the sequence, which implies that the hybrid QSOs are at the transition stage not only from young to old AGNs, but also from a host-dominated phase to an AGN-dominated phase.

  16. On the Importance of Very Light Internally Subsonic AGN Jets in Radio-mode AGN Feedback

    NASA Astrophysics Data System (ADS)

    Guo, Fulai

    2016-07-01

    Radio-mode active galactic nucleus (AGN) feedback plays a key role in the evolution of galaxy groups and clusters. Its physical origin lies in the kiloparsec-scale interaction of AGN jets with the intracluster medium. Large-scale jet simulations often initiate light internally supersonic jets with density contrast 0.01 < η < 1. Here we argue for the first time for the importance of very light (η < 0.01) internally subsonic jets. We investigated the shapes of young X-ray cavities produced in a suite of hydrodynamic simulations, and found that bottom-wide cavities are always produced by internally subsonic jets, while internally supersonic jets inflate cylindrical, center-wide, or top-wide cavities. We found examples of real cavities with shapes analogous to those inflated in our simulations by internally subsonic and internally supersonic jets, suggesting a dichotomy of AGN jets according to their internal Mach numbers. We further studied the long-term cavity evolution, and found that old cavities resulted from light jets spread along the jet direction, while those produced by very light jets are significantly elongated along the perpendicular direction. The northwestern ghost cavity in Perseus is pancake shaped, providing tentative evidence for the existence of very light jets. Our simulations show that very light internally subsonic jets decelerate faster and rise much slower in the intracluster medium than light internally supersonic jets, possibly depositing a larger fraction of jet energy to cluster cores and alleviating the problem of low coupling efficiencies found previously. The internal Mach number points to the jet’s energy content, and internally subsonic jets are energetically dominated by non-kinetic energy, such as thermal energy, cosmic rays, or magnetic fields.

  17. The space density of Compton-thick AGN at z ≈ 0.8 in the zCOSMOS-Bright Survey

    NASA Astrophysics Data System (ADS)

    Vignali, C.; Mignoli, M.; Gilli, R.; Comastri, A.; Iwasawa, K.; Zamorani, G.; Mainieri, V.; Bongiorno, A.

    2014-11-01

    Context. The obscured accretion phase in black hole growth is a crucial ingredient in many models linking the active galactic nuclei (AGN) activity with the evolution of their host galaxy. At present, a complete census of obscured AGN is still missing, although several attempts in this direction have been carried out recently, mostly in the hard X-rays and at mid-infrared wavelengths. Aims: The purpose of this work is to assess whether the [Ne v] emission line at 3426 Å can reliably pick up obscured AGN up to z ≈ 1 by assuming that it is a reliable proxy of the intrinsic AGN luminosity and using moderately deep X-ray data to characterize the amount of obscuration. Methods: A sample of 69 narrow-line (Type 2) AGN at z ≈ 0.65-1.20 were selected from the 20k-zCOSMOS Bright galaxy sample on the basis of the presence of the [Ne v]3426 Å emission. The X-ray properties of these galaxies were then derived using the Chandra-COSMOS coverage of the field; the X-ray-to-[Ne v] flux ratio, coupled with X-ray spectral and stacking analyses, was then used to infer whether Compton-thin or Compton-thick absorption is present in these sources. Then the [Ne v] luminosity function was computed to estimate the space density of Compton-thick AGN at z ≈ 0.8. Results: Twenty-three sources were detected by Chandra, and their properties are consistent with moderate obscuration (on average, ≈a few × 1022 cm-2). The X-ray properties of the remaining 46 X-ray undetected Type 2 AGN (among which we expect to find the most heavily obscured objects) were derived using X-ray stacking analysis. Current data, supported by Monte Carlo simulations, indicate that a fraction as high as ≈40% of the present sample is likely to be Compton thick. The space density of Compton-thick AGN with logL2-10 keV> 43.5 at z = 0.83 is ΦThick = (9.1 ± 2.1) × 10-6 Mpc-3, in good agreement with both X-ray background model expectations and the previously measured space density for objects in a similar

  18. A total and polarized infrared flux view of the AGN clumpy torus

    NASA Astrophysics Data System (ADS)

    Lopez Rodriguez, Enrique

    2013-12-01

    Magnetohydrodynamical theories consider the torus of Active Galactic Nuclei (AGN) to be part of an outflow wind moving away from the central engine. In this framework, the torus is a particular region of the wind, where dusty and optically thick clouds are formed. The outflows are strongly related to the accretion rate and magnetic field strength, which play an important role in the creation, morphology and evolution of the torus. Through infrared (IR) imaging and polarimetry observations, this dissertation (1) searches for signatures of dusty tori in low-luminosity AGN (LLAGN); (2) explores the role and strength of magnetic field in the torus; and (3) investigates the nucleus of radio-loud AGN. Recent theoretical models predicted that LLAGN do not host a Seyfert-like torus, since low-luminosities (<1042 erg s-1 ) cannot sustain the required outflow rate. High-spatial resolution mid-IR (MIR) imaging and nuclear spectral energy distribution of 22 LLAGN reveals different IR characteristics by dividing the sample in terms of the Eddington ratio. These galaxies show a diversity of nuclear morphologies and have a high MIR/X-ray luminosity ratio compared to higher-luminosity AGN. Star formation, jets and/or truncated accretion disk can explain the MIR excess. Although several models have been made to account for the outflowing dusty winds from the central engine, the magnetic field strength at the position of the torus remains poorly characterized. Through a novel study using near-IR polarimetry, the magnetic field strength in the clumpy torus was estimated. Specifically, if paramagnetic alignment is assumed in the dusty clouds of the torus, the magnetic field strength of the torus of IC5063 is estimated to be in the range of 12--128 mG. Alternatively, Chandrasekhar-Fermi method suggests a lower-limit magnetic field strength of 13 mG. For the archetypical radio-loud AGN, Cygnus A, MIR polarimetry using CanariCam on the 10.4-m Gran Telescopio de Canarias revealed a high

  19. Radio-Loud AGN: The Suzaku View

    NASA Technical Reports Server (NTRS)

    Sambruna, Rita

    2009-01-01

    We review our Suzaku observations of Broad-Line Radio Galaxies (BLRGs). The continuum above 2 approx.keV in BLRGs is dominated by emission from an accretion flow, with little or no trace of a jet, which is instead expected to emerge at GeV energies and be detected by Fermi. Concerning the physical conditions of the accretion disk, BLRGs are a mixed bag. In some sources the data suggest relatively high disk ionization, in others obscuration of the innermost regions, perhaps by the jet base. While at hard X-rays the distinction between BLRGs and Seyferts appears blurry, one of the cleanest observational differences between the two classes is at soft X-rays, where Seyferts exhibit warm absorbers related to disk winds while BLRGs do not. We discuss the possibility that jet formation inhibits disk winds, and thus is related to the remarkable dearth of absorption features at soft X-rays in BLRGs and other radio-loud AGN.

  20. Reconfinement shocks in relativistic AGN jets

    SciTech Connect

    Nalewajko, Krzysztof; Sikora, Marek

    2008-12-24

    Stationary knots observed in many AGN jets can be explained in terms of a reconfinement shock that forms when relativistic flow of the jet matter collides with the external medium. The position of these knots can be used, together with information on external pressure profile, to constrain dynamical parameters of the jet. We present a semi-analytical model for the dynamical structure of reconfinement shocks, taking into account exact conservation laws both across the shock surface and in the zone of the shocked jet matter. We show that, due to the transverse pressure gradient in the shock zone, the position of the reconfinement is larger than predicted by simple models. A portion of kinetic energy is converted at the shock surface to internal energy, with efficiency increasing strongly with both bulk Lorentz factor of the jet matter and the jet half-opening angle. Our model may be useful as a framework for modeling non-thermal radiation produced within the stationary features.

  1. The importance of warm, AGN-driven outflows in the nuclear regions of nearby ULIRGs

    NASA Astrophysics Data System (ADS)

    Rodríguez Zaurín, J.; Tadhunter, C. N.; Rose, M.; Holt, J.

    2013-06-01

    We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the near-nuclear (r ≲ 3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s-1) and/or strongly blueshifted (ΔV < -150 km s-1) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their [O III] λλ5007, 4959 emission lines are broader and more asymmetric. The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong [O III] λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs - consistent with the requirements of the hydrodynamic simulations that include

  2. AGN coronal emission models - I. The predicted radio emission

    NASA Astrophysics Data System (ADS)

    Raginski, I.; Laor, Ari

    2016-06-01

    Accretion discs in active galactic nucleus (AGN) may be associated with coronal gas, as suggested by their X-ray emission. Stellar coronal emission includes radio emission, and AGN corona may also be a significant source for radio emission in radio quiet (RQ) AGN. We calculate the coronal properties required to produce the observed radio emission in RQ AGN, either from synchrotron emission of power-law (PL) electrons, or from cyclosynchrotron emission of hot mildly relativistic thermal electrons. We find that a flat spectrum, as observed in about half of RQ AGN, can be produced by corona with a disc or a spherical configuration, which extends from the innermost regions out to a pc scale. A spectral break to an optically thin power-law emission is expected around 300-1000 GHz, as the innermost corona becomes optically thin. In the case of thermal electrons, a sharp spectral cut-off is expected above the break. The position of the break can be measured with very long baseline interferometry observations, which exclude the cold dust emission, and it can be used to probe the properties of the innermost corona. Assuming equipartition of the coronal thermal energy density, the PL electrons energy density, and the magnetic field, we find that the energy density in a disc corona should scale as ˜R-1.3, to get a flat spectrum. In the spherical case the energy density scales as ˜R-2, and is ˜4 × 10-4 of the AGN radiation energy density. In Paper II we derive additional constraints on the coronal parameters from the Gudel-Benz relation, Lradio/LX-ray ˜ 10- 5, which RQ AGN follow.

  3. X-ray View of Four High-Luminosity Swift-BAT AGN: Unveiling Obscuration and Reflection with Suzaku

    NASA Technical Reports Server (NTRS)

    Fiorettil, V.; Angelini, L.; Mushotzky, R. F.; Koss, M.; Malaguti, G.

    2013-01-01

    Aims. A complete census of obscured Active Galactic Nuclei (AGN) is necessary to reveal the history of the super massive black hole (SMBH) growth and galaxy evolution in the Universe given the complex feedback processes and the fact that much of this growth occurs in an obscured phase. In this context, hard X-ray surveys and dedicated follow-up observations represent a unique tool for selecting highly absorbed AGN and for characterizing the obscuring matter surrounding the SMBH. Here we focus on the absorption and reflection occurring in highly luminous, quasar-like AGN, to study the relation between the geometry of the absorbing matter and the AGN nature (e.g. X-ray, optical, and radio properties), and to help to determine the column density dependency on the AGN luminosity. Methods. The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10(exp -11) erg per square centimeter and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 less than LogLBAT less than 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis, adding an original spectral analysis when non was available from the literature. Results. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption (N(sub H) approximately 4 × 10(exp 23) per square centimeter) and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (less than 0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density

  4. The Cosmic History of Hot Gas Cooling and Radio AGN Activity in Massive Early-Type Galaxies

    NASA Technical Reports Server (NTRS)

    Danielson, A. L. R.; Lehmer, B. D.; Alexander, D. M.; Brandt, W. M.; Luo, B.; Miller, N.; Xue, Y. Q.; Stott, J. P.

    2012-01-01

    We study the X-ray properties of 393 optically selected early-type galaxies (ETGs) over the redshift range of z approx equals 0.0-1.2 in the Chandra Deep Fields. To measure the average X-ray properties of the ETG population, we use X-ray stacking analyses with a subset of 158 passive ETGs (148 of which were individually undetected in X-ray). This ETG subset was constructed to span the redshift ranges of z = 0.1-1.2 in the approx equals 4 Ms CDF-S and approx equals 2 Ms CDF-N and z = 0.1-0.6 in the approx equals 250 ks E-CDF-S where the contribution from individually undetected AGNs is expected to be negligible in our stacking. We find that 55 of the ETGs are detected individually in the X-rays, and 12 of these galaxies have properties consistent with being passive hot-gas dominated systems (i.e., systems not dominated by an X-ray bright Active Galactic Nucleus; AGN). On the basis of our analyses, we find little evolution in the mean 0.5-2 keY to B-band luminosity ratio (L(sub x) /L(sub Beta) varies as [1 +z]) since z approx equals 1.2, implying that some heating mechanism prevents the gas from cooling in these systems. We consider that feedback from radio-mode AGN activity could be responsible for heating the gas. We select radio AGNs in the ETG population using their far-infrared/radio flux ratio. Our radio observations allow us to constrain the duty cycle history of radio AGN activity in our ETG sample. We estimate that if scaling relations between radio and mechanical power hold out to z approx equals 1.2 for the ETG population being studied here, the average mechanical power from AGN activity is a factor of approx equals1.4 -- 2.6 times larger than the average radiative cooling power from hot gas over the redshift range z approx equals 0-1.2. The excess of inferred AGN mechanical power from these ETGs is consistent with that found in the local Universe for similar types of galaxies.

  5. The MIXR sample or: how I learned to stop worrying and love multiwavelength catalogue cross-correlations

    NASA Astrophysics Data System (ADS)

    Mingo, Beatriz; Watson, Mike; Stewart, Gordon; Rosen, Simon; Blain, Andrew; Hardcastle, Martin; Mateos, Silvia; Carrera, Francisco; Ruiz, Angel; Pineau, Francois-Xavier

    2016-08-01

    We cross-match 3XMM, WISE and FIRST/NVSS to create the largest-to-date mid-IR, X-ray, and radio (MIXR) sample of galaxies and AGN. We use MIXR to triage sources and efficiently and accurately pre-classify them as star-forming galaxies or AGN, and to highlight bias and shortcomings in current AGN sample selection methods, paving the way for the next generation of instruments. Our results highlight key questions in AGN science, such as the need for a re-definition of the radio-loud/radio-quiet classification, and our observed lack of correlation between the kinetic (jet) and radiative (luminosity) output in AGN, which has dramatic potential consequences on our current understanding of AGN accretion, variability and feedback.

  6. Exploring X-ray and radio emission of type 1 AGN up to z ~ 2.3

    NASA Astrophysics Data System (ADS)

    Ballo, L.; Heras, F. J. H.; Barcons, X.; Carrera, F. J.

    2012-09-01

    Context. X-ray emission from active galactic nuclei (AGN) is dominated by the accretion disk around a supermassive black hole. The radio luminosity, however, has not such a clear origin except in the most powerful sources where jets are evident. The origin (and even the very existence) of the local bi-modal distribution in radio-loudness is also a debated issue. Aims: By analysing X-ray, optical and radio properties of a large sample of type 1 AGN and quasars (QSOs) up to z > 2, where the bulk of this population resides, we aim to explore the interplay between radio and X-ray emission in AGN, in order to further our knowledge on the origin of radio emission, and its relation to accretion. Methods: We analyse a large (~800 sources) sample of type 1 AGN and QSOs selected from the 2XMMi XMM-Newton X-ray source catalogue, cross-correlated with the SDSS DR7 spectroscopic catalogue, covering a redshift range from z ~ 0.3 to z ~ 2.3. Supermassive black hole masses are estimated from the Mg ii emission line, bolometric luminosities from the X-ray data, and radio emission or upper limits from the FIRST catalogue. Results: Most of the sources accrete close to the Eddington limit and the distribution in radio-loudness does not appear to have a bi-modal behaviour. We confirm that radio-loud AGN are also X-ray loud, with an X-ray-to-optical ratio up to twice that of radio-quiet objects, even excluding the most extreme strongly jetted sources. By analysing complementary radio-selected control samples, we find evidence that these conclusions are not an effect of the X-ray selection, but are likely a property of the dominant QSO population. Conclusions: Our findings are best interpreted in a context where radio emission in AGN, with the exception of a minority of beamed sources, arises from very close to the accretion disk and is therefore heavily linked to X-ray emission. We also speculate that the radio-loud/radio-quiet dichotomy might either be an evolutionary effect that

  7. AGN host galaxy mass function in COSMOS. Is AGN feedback responsible for the mass-quenching of galaxies?

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Schulze, A.; Merloni, A.; Zamorani, G.; Ilbert, O.; La Franca, F.; Peng, Y.; Piconcelli, E.; Mainieri, V.; Silverman, J. D.; Brusa, M.; Fiore, F.; Salvato, M.; Scoville, N.

    2016-04-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate, that is, λSAR, the distribution function (SARDF), up to z ~ 2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best-fit model characterizes the SARDF as a double power-law with mass-dependent but redshift-independent break, whose low λSAR slope flattens with increasing redshift while the normalization increases. This implies that for a given stellar mass, higher λSAR objects have a peak in their space density at earlier epoch than the lower λSAR objects, following and mimicking the well-known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with an almost constant M∗⋆ and a low-mass slope α that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that up to log (M⋆/M⊙) ~ 11.5, the ratio of AGN host galaxies to star-forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate subclasses with a previously published phenomenological model prediction for the "transient" population, which are galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, that is, M⋆ > 1010.7 M⊙, feedback from luminous AGN (log Lbol ≳ 46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.

  8. Inverse Compton X-ray signature of AGN feedback

    NASA Astrophysics Data System (ADS)

    Bourne, Martin A.; Nayakshin, Sergei

    2013-12-01

    Bright AGN frequently show ultrafast outflows (UFOs) with outflow velocities vout ˜ 0.1c. These outflows may be the source of AGN feedback on their host galaxies sought by galaxy formation modellers. The exact effect of the outflows on the ambient galaxy gas strongly depends on whether the shocked UFOs cool rapidly or not. This in turn depends on whether the shocked electrons share the same temperature as ions (one-temperature regime, 1T) or decouple (2T), as has been recently suggested. Here we calculate the inverse Compton spectrum emitted by such shocks, finding a broad feature potentially detectable either in mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue that current observations of AGN do not seem to show evidence for the 1T component. The limits on the 2T emission are far weaker, and in fact it is possible that the observed soft X-ray excess of AGN is partially or fully due to the 2T shock emission. This suggests that UFOs are in the energy-driven regime outside the central few pc, and must pump considerable amounts of not only momentum but also energy into the ambient gas. We encourage X-ray observers to look for the inverse Compton components calculated here in order to constrain AGN feedback models further.

  9. A Meeting on the AGN/Galaxy Connection

    NASA Technical Reports Server (NTRS)

    Kinney, Anne

    1999-01-01

    This grant was used for travel support of several junior astronomers to attend the meeting "The Actice Galactic Nuclei (AGN)/Normal Galaxy Connection", Session El.2 of the 32nd COSPAR Assembly held in Nagoya, Japan, 12-19 July 1998. This meeting included the contributions from both theoretical and observational astronomers to the following fundamental questions: What causes the activity in galaxies? What is the difference between normal and active galaxies? Which processes are responsible for fueling the AGN? Do all galaxies have central Black Holes? What is the difference between low and high luminosity AGN? The observational papers discussed themes like: the detection of the black hole at the nucleus of our Galaxy, as well as in other galaxies; results from surveys of AGN in local galaxies, the source of their activity and their cold gas content; the observations of quasar host galaxies; the properties of Ultraluminous Infrared Galaxies. These papers used data from ground based observatories and several space missions (e.g. ASCA, ROSAT, HST, ISO) in wavebands from radio through gamma-rays. The theoretical papers discussed issues like: mechanisms to fuel the AGN; the physics of the accretion process; the formation of black-holes, quasars and their jets.

  10. THE FIELD X-RAY AGN FRACTION TO z = 0.7 FROM THE CHANDRA MULTIWAVELENGTH PROJECT AND THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Haggard, Daryl; Anderson, Scott F.; Green, Paul J.; Aldcroft, Tom L.; Kim, Dong-Woo; Constantin, Anca; Barkhouse, Wayne A.

    2010-11-10

    We employ the Chandra Multiwavelength Project (ChaMP) and the Sloan Digital Sky Survey (SDSS) to study the fraction of X-ray-active galaxies in the field to z = 0.7. We utilize spectroscopic redshifts from SDSS and ChaMP, as well as photometric redshifts from several SDSS catalogs, to compile a Parent sample of more than 100,000 SDSS galaxies and nearly 1600 Chandra X-ray detections. Detailed ChaMP volume completeness maps allow us to investigate the local fraction of active galactic nuclei (AGNs), defined as those objects having broadband X-ray luminosities L{sub X} (0.5-8 keV) {>=}10{sup 42} erg s{sup -1}, as a function of absolute optical magnitude, X-ray luminosity, redshift, mass, and host color/morphological type. In five independent samples complete in redshift and i-band absolute magnitude, we determine the field AGN fraction to be between 0.16% {+-} 0.06% (for z {<=} 0.125 and -18>M{sub i} > - 20) and 3.80% {+-} 0.92% (for z {<=} 0.7 and M{sub i} < -23). We find excellent agreement between our ChaMP/SDSS field AGN fraction and the Chandra cluster AGN fraction, for samples restricted to similar redshift and absolute magnitude ranges: 1.19% {+-} 0.11% of ChaMP/SDSS field galaxies with 0.05 < z < 0.31 and absolute R-band magnitude more luminous than M{sub R} < -20 are AGNs. Our results are also broadly consistent with measures of the field AGN fraction in narrow, deep fields, though differences in the optical selection criteria, redshift coverage, and possible cosmic variance between fields introduce larger uncertainties in these comparisons.

  11. The Overdue Discovery of Quasars and AGN

    NASA Astrophysics Data System (ADS)

    Kellermann, Ken I.

    2012-09-01

    The extragalactic nature of quasars as a major new component of the Universe was not recognized until 1963 when Maarten Schmidt somewhat accidentally measured the spectrum of 3C 273 and recognized that the relatively simple hydrogen line Balmer series spectrum implied a redshift of 0.16. Curiously, 3C 48 and other very compact radio sources had been previously identified with ``quasi-stellar'' objects several years earlier. Even though the redshift of 3C48 was measured as early as 1960 as 0.37, it was rejected due to apparent spectroscopic technicalities and preconceived ideas about what appeared to be an unrealistically high luminosity. The strong radio source known as 3C 273 was first catalogued in 1959 and the now recognized magnitude 13 optical counterpart was known at least as early as 1887. Although, since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions, interestingly, 3C273 eluded identification until a series of lunar occultations by Hazard et al. in 1962 were used to determine the position and morphology of the radio source. Acceptance of the cosmological nature of quasars and the implied excessive radio and optical luminosity was not universal, and claims for a more local population continued for at least several decades, confused perhaps by the recognition of the much larger class of radio quiet quasi stellar objects and active galactic nuclei (AGN), the uncertain connection with previously known Seyfert and other compact galaxies, as well as attempts to classify quasars into numerous sub-categories based on their observed optical, radio, IR and high energy properties.

  12. Agnes Pockels: Life, Letters and Papers

    NASA Astrophysics Data System (ADS)

    Helm, Christiane A.

    2004-03-01

    Agnes Pockels (1862 - 1935) was a German woman, whose studies pioneered surface science. She was born in malaria infected North Italy while her father served in the Austrian army. Because he suffered adverse health effects, the family moved in1871 to Braunschweig (North Germany). There, Pockels went to high school. She was interested in science, but formal training was not available for girls. She took on the role of household manager and nurse as her parents' health deteriorated further. Her diary illustrates the difficulties she faced in trying to maintain her own health, the health of her parents and her scientific research at the same time. When Pockels was 18 or 19, she designed a ring tensiometer. Additionally, she found a new method to introduce water-insoluble compounds to the water surface by dissolving them in an organic solvent, and applying drops of the solution. Her surface film balance technique from 1882 is the basis for the method later developed by Langmuir. Since her experimental work was highly original and in a new field, she failed to get it recognized in her own country. When she was 28, she wrote to Lord Rayleigh, since she had read about his recent experiments in surface physics. Rayleigh was so impressed with her experimental methods and results that he had her letter translated from German and published it in Nature (1891). She continued her research on surface films, interactions of solutions and contact angles (more papers, 3 in Nature). Still, she did all experiments at home. With the death of her brother in 1913 and the onset of the war, she retired into private life. Thus she was surprised when she was awarded in her late 60ies with a honorary doctorate by the TU Braunschweig (1932) and the annual prize of the German Colloid Society (1931).

  13. AGN variability in the radio band

    NASA Astrophysics Data System (ADS)

    Max-Moerbeck, Walter

    2016-08-01

    Variability is an important and defining characteristic of AGN, that along with their broadband spectral energy distribution make their study interesting and challenging. A complete understanding of the physics of these objects requires monitoring observations over the whole electromagnetic spectrum, and includes studying their properties at a given band and also the relationship between multiple wavelengths. Here we present the main results obtained so far with the ongoing OVRO 40m blazar monitoring program at 15 GHz with twice a week cadence. This program started in mid-2007 and is currently monitoring about 1800 blazars, including most of the bright blazars north of declination -20 degrees. These results include: characterization of the variability in the radio band; its relationship with optical and gamma-ray properties; and its relationship to gamma-ray emission as observed with Fermi-LAT, which can provide constrains on the location of the gamma-ray emission region. We will also discuss our ongoing work on the characterization of radio variability using the power spectral density. For this, we are using 8 years of OVRO 40m data for ~1200 sources, and also F-GAMMA monitoring data taken with the Effelsberg 100m telescope for 60 sources with about monthly cadence monitoring data at 8 frequencies between 2.6 and 43.0 GHz. These studies will provide an improved understanding of blazar variability, a better basis to evaluate the statistics of correlated variability between different emission bands, and a long and consistent record of radio observations to be used in gamma-ray and multi-wavelength investigations.

  14. The BLR structure and dust torus size of AGN - Implications from photometric and dust reverberation mapping campaigns.

    NASA Astrophysics Data System (ADS)

    Pozo Nuñez, F.; Ramolla, M.; Westhues, C.; Haas, M.; Chini, R.; Steenbrugge, K.; Lemke, R.; Murphy, M.

    2014-03-01

    Photometric reverberation mapping (PRM) is a novel method used to study the geometry of the broad emission-line region (BLR), black hole masses and host-subtracted luminosities of active galactic nuclei (AGN). We obtained high-quality sampling data with small (15 to 80 cm) robotic telescopes at the observatory of the Ruhr-University Bochum, located in the Atacama desert in Chile.

  15. The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties

    NASA Technical Reports Server (NTRS)

    Gofford, Jason; Reeves, James N.; Tombesi, Francesco; Braito, Valentina; Turner, T. Jane; Miller, Lance; Cappi, Massimo

    2013-01-01

    We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Healpha and/or Fe XXVI Lyalpha absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E greater than or approximately equal to 6.7 keV in 20/51 sources at the P(sub MC) greater than or equal tov 95 per cent level, which corresponds to approximately 40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Healpha and Fe XXVI Lyalpha at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N(sub H) per square centimeter)) is approximately equal to 23 and log (Xi/erg centimeter per second) is approximately equal to 4.5, respectively. Measured outflow velocities span a continuous range from less than1500 kilometers per second up to approximately100 000 kilometers per second, with mean and median values of approximately 0.1 c and approximately 0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.

  16. The missing piece of the puzzle: low-luminosity AGN in the Unified Model

    NASA Astrophysics Data System (ADS)

    Mezcua, Mar; Prieto, Almudena; Fernandez Ontiveros, Juan Antonio

    One of the puzzling questions in AGN studies is whether the Unified Model for AGN also holds for the most numerous class among them: low-luminosity AGN (LLAGN; Lbol<=10(42) erg/s). LLAGN outstand from the Unified Model as lacking the big blue bump in the optical-UV, footprint of the accretion disk, and being radiatively inefficient. A possible explanation is that the overall energy output in these faint nuclei is dominated by a jet. This scenario is supported by the finding that: (1) the high-spatial-resolution spectral energy distribution (SED) of some LLAGN is well described by non-thermal synchrotron jet emission from radio to the UV; and (2) 67% LLAGN in the Palomar Sample observed at sub-arcsec resolution present extended or marginally resolved radio cores, most of them with a flat or slightly inverted radio spectrum and non-thermal brightness temperatures above 10(5) K footprint of a relativistic jet. In this work we also present the detection of extended jet-like radio structures in NGC 1097 and NGC 2911 and the first resolved parsec-scale jet in the nucleus of the Sombrero galaxy, based on the analysis of sub-arcsec resolution radio data of a sample of nearby LLAGN for which high-spatial-resolution SED of their core emission is available. This allows us to investigate their energetic balance without drawing on (most) of the ad-hoc assumptions usually considered in large statistical surveys. We find that most of the LLAGN in the sample show a kinematic jet luminosity larger than the radiated bolometric luminosity, in agreement with previous statistical studies, which indicates that the jet kinematic output dominates the nuclear energetics of LLAGN. However, our individualized study reveals that the total bolometric luminosity is larger than the jet power in those sources without detected large-scale (> 100 parsec) jet radio emission. Finally, we find that the Eddington ratios are highly sub-Eddington (<10(-4) ) even when adding the jet power to the total

  17. AGN feedback and jet-induced star formation

    NASA Astrophysics Data System (ADS)

    Salomé, Q.; Salomé, P.; Combes, F.; Hamer, S.

    2015-12-01

    We studied the impact of the AGN in radio galaxies on star formation along the radio jet. Our main goal was to determine whether star formation is more efficient in the shocked region along the jet. A first large scale work based on IRAM-30m CO observations of 3C 285 and Minkowski's Object has shown the star-forming spots located a few tens of kpc along the radio jet appears to form stars at least as efficiently as typical spiral galaxies or even boosted. This result supports the AGN positive feedback scenario. On the opposite, a small scale multi-wavelength analysis of the northern filaments of Centaurus A tends to quench star formation in the filaments, maybe due to the AGN negative feedback.

  18. The predominance of dust in the polar region of AGN

    NASA Astrophysics Data System (ADS)

    Asmus, Daniel; Hönig, Sebastian; Gandhi, Poshak

    2016-08-01

    Recent mid-infrared (MIR) interferometric observations showed in few AGN that the bulk of the infrared emission originates from the polar region above the putative torus, where only little dust should be present. Our investigation of 149 Seyferts with high angular resolution MIR images from, e.g., VLT/VISIR shows that significant polar dust emission is probably very common in AGN. The relative amount of resolved MIR emission is at least 40 per cent and scales with the narrow emission line fluxes implying a strong connection between the extended continuum and line emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGN. We will discuss some of the resulting implications and give prospects for future instruments to further test this scenario.

  19. The contribution of AGNs to the X-ray background.

    NASA Astrophysics Data System (ADS)

    Comastri, A.; Setti, G.; Zamorani, G.; Hasinger, G.

    1995-04-01

    We report the results of a detailed analysis of the contribution of various classes of AGNs (Seyfert galaxies and quasars) to the extragalactic X-ray background (XRB). The model is based on the unification schemes of AGNs, on their related X-ray spectral properties in the light of recent observational results and on the X-ray luminosity function derived by Boyle et al. (1993). The integrated emission from AGNs, when folded with an appropriate cosmological evolution law, can provide a good fit to the XRB over a wide energy range, from several to ~100keV, while it contributes only about 74% of the ROSAT soft XRB. The baseline model predictions have been checked against all available observational constraints from both hard and soft X-ray surveys (counts, redshift distributions and average X-ray source spectral properties).

  20. The central parsecs of AGN across the electromagnetic spectrum

    NASA Astrophysics Data System (ADS)

    Prieto, Almudena

    2016-08-01

    High angular resolution observations across the electromagnetic spectrum of the nearest AGN are providing a view of the nuclear region rather different from- and somewhat simpler than-the one envisaged by the canonical AGN Unification Schemes. I will review the challenges that parsec-scale observations in the IR when combined with comparable physical scales in radio, millimetre, optical, UV and X-ray of some of the nearest AGN are revealing about the nature of the nuclear emission, the transition from the most luminous to the feeble ones, and their accretion power. I will discuss how these observations challenge the requirement of a torus and question one of its fundamental attributes which is the collimation of the nuclear radiation.

  1. Feedback Mechanisms of Starbursts and AGNs through Molecular Outflows

    NASA Astrophysics Data System (ADS)

    Matsushita, S.; Krips, M.; Lim, J.; Muller, S.; Tsai, A.-L.

    2013-10-01

    Our deep molecular line images of nearby starburst galaxies and AGNs exhibit molecular outflows in most galaxies, and have revealed that the molecular outflows co-exist with outflows or jets seen in other wavelengths. In case of starbursts, X-ray outflows have higher energy and pressure than those of molecular outflows, suggesting that plasma outflows are blowing the molecular gas away from starburst regions, which suggests a strong negative feedback. On the other hand, current starburst regions in M82 can be seen at the inner edge of an expanding molecular bubble, suggesting a positive feedback. In case of AGNs, jets seem to entrain the surrounding molecular gas away from the AGNs, suggesting a negative feedback.

  2. Quenching histories of galaxies and the role of AGN feedback

    NASA Astrophysics Data System (ADS)

    Smethurst, Rebecca Jane; Lintott, Chris; Simmons, Brooke; Galaxy Zoo Team

    2016-01-01

    Two open issues in modern astrophysics are: (i) how do galaxies fully quench their star formation and (ii) how is this affected - or not - by AGN feedback? I present the results of a new Bayesian-MCMC analysis of the star formation histories of over 126,000 galaxies across the colour magnitude diagram showing that diverse quenching mechanisms are instrumental in the formation of the present day red sequence. Using classifications from Galaxy Zoo we show that the rate at which quenching can occur is morphologically dependent in each of the blue cloud, green valley and red sequence. We discuss the nature of these possible quenching mechanisms, considering the influence of secular evolution, galaxy interactions and mergers, both with and without black hole activity. We focus particularly on the relationship between these quenched star formation histories and the presence of an AGN by using this new Bayesian method to show a population of type 2 AGN host galaxies have recently (within 2 Gyr) undergone a rapid (τ < 1 Gyr) drop in their star formation rate. With this result we therefore present the first statistically supported observational evidence that AGN feedback is an important mechanism for the cessation of star formation in this population of galaxies. The diversity of this new method also highlights that such rapid quenching histories cannot account fully for all the quenching across the current AGN host population. We demonstrate that slower (τ > 2 Gyr) quenching rates dominate for high stellar mass (log10[M*/M⊙] > 10.75) hosts of AGN with both early- and late-type morphology. We discuss how these results show that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes across the entirety of the colour magnitude diagram.

  3. On the electron-positron cascade in AGN central engines

    NASA Astrophysics Data System (ADS)

    Ford, Alex; Keenan, Brett; Medvedev, Mikhail

    2016-03-01

    Processes around spinning supermassive black holes (BH) in active galactic nuclei (AGN) are believed to determine how relativistic jets are launched and how the BH energy is extracted. The key ``ingredient'' is the origin of plasma in BH magnetospheres. In order to explore the process of the electron-positron plasma production, we developed a numerical code which models a one-dimensional (along a magnetic field line) dynamics of the cascade. Our simulations show that plasma production is controlled by the spectrum of the ambient photon field, the B-field strength, the BH spin and mass. Implications of our results to the Galactic Center and AGNs are discussed.

  4. Viscous time lags between starburst and AGN activity

    NASA Astrophysics Data System (ADS)

    Blank, Marvin; Duschl, Wolfgang J.

    2016-10-01

    There is strong observational evidence indicating a time lag of order of some 100 Myr between the onset of starburst and AGN activity in galaxies. Dynamical time lags have been invoked to explain this. We extend this approach by introducing a viscous time lag the gas additionally needs to flow through the AGN's accretion disc before it reaches the central black hole. Our calculations reproduce the observed time lags and are in accordance with the observed correlation between black hole mass and stellar velocity dispersion.

  5. HST Imaging of Fading AGN Candidates. I. Host-galaxy Properties and Origin of the Extended Gas

    NASA Astrophysics Data System (ADS)

    Keel, William C.; Maksym, W. Peter; Bennert, Vardha N.; Lintott, Chris J.; Chojnowski, S. Drew; Moiseev, Alexei; Smirnova, Aleksandrina; Schawinski, Kevin; Urry, C. Megan; Evans, Daniel A.; Pancoast, Anna; Scott, Bryan; Showley, Charles; Flatland, Kelsi

    2015-05-01

    We present narrow- and medium-band Hubble Space Telescope imaging, with additional supporting ground-based imaging, spectrophotometry, and Fabry-Perot interferometric data, for eight galaxies identified as hosting a fading active galactic nucleus (AGN). These are selected to have AGN-ionized gas projected \\gt 10 kpc from the nucleus and energy budgets with a significant shortfall of ionizing radiation between the requirement to ionize the distant gas and the AGN as observed directly, indicating fading of the AGN on ≈50,000 yr timescales. This paper focuses on the host-galaxy properties and origin of the gas. In every galaxy, we identify evidence of ongoing or past interactions, including tidal tails, shells, and warped or chaotic dust structures; a similarly selected sample of obscured AGNs with extended ionized clouds shares this high incidence of disturbed morphologies. Several systems show multiple dust lanes in different orientations, broadly fit by differentially precessing disks of accreted material viewed ˜1.5 Gyr after its initial arrival. The host systems are of early Hubble type; most show nearly pure de Vaucouleurs surface brightness profiles and Sérsic indices appropriate for classical bulges, with one S0 and one SB0 galaxy. The gas has a systematically lower metallicity than the nuclei; three systems have abundances uniformly well below solar, consistent with an origin in tidally disrupted low-luminosity galaxies, while some systems have more nearly solar abundances (accompanied by such signatures as multiple Doppler components), which may suggest redistribution of gas by outflows within the host galaxies themselves. These aspects are consistent with a tidal origin for the extended gas in most systems, although the ionized gas and stellar tidal features do not always match closely. Unlike extended emission regions around many radio-loud AGNs, these clouds are kinematically dominated by rotation, in some cases in warped disks. Outflows can play

  6. Evolutionary behaviour of AGN: Investigations on BL Lac objects and Seyfert II galaxies

    NASA Astrophysics Data System (ADS)

    Beckmann, V.

    2000-12-01

    The evolution and nature of AGN is still one of the enigmatic questions in astrophysics. While large and complete Quasar samples are available, special classes of AGN, like BL Lac objects and Seyfert II galaxies, are still rare objects. In this work I present two new AGN samples. The first one is the HRX-BL Lac survey, resulting in a sample of X-ray selected BL Lac objects. This sample results from 223 BL Lac candidates based on a correlation of X-ray sources with radio sources. The identification of this sample is 98% complete. 77 objects have been identified as BL Lac objects and form the HRX-BL Lac complete sample, the largest homogeneous sample of BL Lac objects existing today. For this sample, redshifts are now known for 62 objects (81 %). In total I present 101 BL Lac objects in the enlarged HRX-BL Lac survey, for which redshift information is available for 84 objects. During the HRX-BL Lac survey I found several objects of special interest. 1ES 1517+656 turned out to be the brightest known BL Lac object in the universe. 1ES 0927+500 could be the first BL Lac object with a line detected in the X-ray region. RX J1211+2242 is probably the the counterpart of the up to now unidentified gamma-ray source 3EG J1212+2304. Additionally I present seven candidates for ultra high frequency peaked BL Lac objects. RX J1054+3855 and RX J1153+3517 are rare high redshift X-ray bright QSO or accreting binary systems with huge magnetic fields. For the BL Lac objects I suggest an unified scenario in which giant elliptical galaxies, formed by merging events of spiral galaxies at z > 2, start as powerful, radio dominated BL Lacs. As the jet gets less powerful, the BL Lacs start to get more X-ray dominated, showing less total luminosities (for z < 1). This effect is seen in the different evolutionary behavior detected in high and low frequency cut off BL Lac objects (HBL and LBL, respectively). The model of negative evolution is supported by assumptions about the energetic effects

  7. AGN and Starbursts in Dusty Galaxy Mergers: Insights from the Great Observatories All-sky LIRG Survey

    NASA Astrophysics Data System (ADS)

    Mazzarella, Joseph M.

    2014-07-01

    The Great Observatories All-sky LIRG Survey (GOALS) is combining imaging and spectroscopic data from the Herschel, Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes augmented with extensive ground-based observations in a multiwavelength study of approximately 180 Luminous Infrared Galaxies (LIRGs) and 20 Ultraluminous Infrared Galaxies (ULIRGs) that comprise a statistically complete subset of the 60μm-selected IRAS Revised Bright Galaxy Sample. The objects span the full range of galaxy environments (giant isolated spirals, wide and close pairs, minor and major mergers, merger remnants) and nuclear activity types (Seyfert 1, Seyfert 2, LINER, starburst/HII), with proportions that depend strongly on the total infrared luminosity. I will review the science motivations and present highlights of recent results selected from over 25 peer-reviewed journal articles published recently by the GOALS Team. Statistical investigations include detection of high-ionization Fe K emission indicative of deeply embedded AGN, comparison of UV and far-IR properties, investigations of the fraction of extended emission as a function of wavelength derived from mid-IR spectroscopy, mid-IR spectral diagnostics and spectral energy distributions revealing the relative contributions of AGN and starbursts to powering the bolometric luminosity, and quantitative structure analyses that delineate the evolution of stellar bars and nuclear stellar cusps during the merger process. Multiwavelength dissections of individual systems have unveiled large populations of young star clusters and heavily obscured AGN in early-stage (II Zw 96), intermediate-stage (Mrk 266, Mrk 273), and late-stage (NGC 2623, IC 883) mergers. A recently published study that matches numerical simulations to the observed morphology and gas kinematics in mergers has placed four systems on a timeline spanning 175-260 million years after their first passages, and modeling of additional (U)LIRGs is underway. A very

  8. The Hard X-ray 20-40 keV AGN Luminosity Function

    NASA Technical Reports Server (NTRS)

    Beckmann, V.; Soldi, S.; Shrader, C. R.; Gehrels, N.; Produit, N.

    2006-01-01

    We have compiled a complete, significance limited extragalactic sample based on approximately 25,000 deg(sup 2) to a limiting flux of 3 x 10(exp -11) ergs per square centimeter per second. (approximately 7,000 deg(sup 2)) to a flux limit of 10(exp -11) ergs per square centimeter per second)) in the 20 - 40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66 plus or minus 0.11. The integration of the cumulative flux per unit area leads to f(sub 20-40 keV) = 2.6 x 10(exp -10) ergs per square centimeter per second per sr(sup -1) which is about 1% of the known 20-40 keV X-ray background. We present the first luminosity function of AGN in the 20-40 keV energy range, based on 68 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma (sub 1) = 0.9 below, and gamma (sub 2) = 2.2 above the turn-over luminosity of L(sub *), = 4.6 x 10(sup 43) ergs per second. The emissivity of all INTEGRAL AGNs per unit volume is W(sub 20-40keV)(greater than 10(sup 41) ergs per second) = 2.8 x 10(sup 38) ergs per second h(sup 3)(sub 70) Mpc(sup -3). These results are consistent with those derived in the 2-20keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (z(raised bar) = 0.022)), only limited conclusions can be drawn for the evolution of AGNs in this energy band. But the objects explaining the peak in the cosmic X-ray background are likely to be either low luminosity AGN (L(sub x) less than 10(sup 41) ergs per second) or of other type, such as intermediate mass black holes, clusters, and star forming regions.

  9. High precision X-ray log N - log S distributions: implications for the obscured AGN population

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Warwick, R. S.; Carrera, F. J.; Stewart, G. C.; Ebrero, J.; Della Ceca, R.; Caccianiga, A.; Gilli, R.; Page, M. J.; Treister, E.; Tedds, J. A.; Watson, M. G.; Lamer, G.; Saxton, R. D.; Brunner, H.; Page, C. G.

    2008-12-01

    Context: Our knowledge of the properties of AGN, especially those of optical type-2 objects, is very incomplete. Because extragalactic source count distributions are dependent on the cosmological and statistical properties of AGN, they provide a direct method of investigating the underlying source populations. Aims: We aim to constrain the extragalactic source count distributions over a broad range of X-ray fluxes and in various energy bands to test whether the predictions from X-ray background synthesis models agree with the observational constraints provided by our measurements. Methods: We have used 1129 XMM-Newton observations at |b|>20° covering a total sky area of 132.3 deg2 to compile the largest complete samples of X-ray selected objects to date both in the 0.5-1 keV, 1-2 keV, 2-4.5 keV, 4.5-10 keV bands employed in standard XMM-Newton data processing and in the 0.5-2 keV and 2-10 keV energy bands more usually considered in source count studies. Our survey includes in excess of 30 000 sources and spans fluxes from 10-15 to 10-12 erg cm^{-2 s-1} below 2 keV and from 10-14 to 10-12 erg cm^{-2 s-1} above 2 keV where the bulk of the cosmic X-ray background energy density is produced. Results: The very large sample size we obtained means our results are not limited by cosmic variance or low counting statistics. A break in the source count distributions was detected in all energy bands except the 4.5-10 keV band. We find that an analytical model comprising 2 power-law components cannot adequately describe the curvature seen in the source count distributions. The shape of the log N(>S) - log S is strongly dependent on the energy band with a general steepening apparent as we move to higher energies. This is due to the fact that non-AGN populations, comprised mainly of stars and clusters of galaxies, contribute up to 30% of the source population at energies <2 keV and at fluxes ≥10-13 erg cm^{-2 s-1}, and these populations of objects have significantly flatter

  10. Pan-STARRS1 variability of XMM-COSMOS AGN. I. Impact on photometric redshifts

    NASA Astrophysics Data System (ADS)

    Simm, T.; Saglia, R.; Salvato, M.; Bender, R.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2015-12-01

    Aims: Upcoming large area sky surveys like Euclid and eROSITA, which are dedicated to studying the role of dark energy in the expansion history of the Universe and the three-dimensional mass distribution of matter, crucially depend on accurate photometric redshifts. The identification of variable sources, such as active galactic nuclei (AGNs), and the achievable redshift accuracy for varying objects are important in view of the science goals of the Euclid and eROSITA missions. Methods: We probe AGN optical variability for a large sample of X-ray-selected AGNs in the XMM-COSMOS field, using the multi-epoch light curves provided by the Pan-STARRS1 (PS1) 3π and Medium Deep Field surveys. To quantify variability we employed a simple statistic to estimate the probability of variability and the normalized excess variance to measure the variability amplitude. Utilizing these two variability parameters, we defined a sample of varying AGNs for every PS1 band. We investigated the influence of variability on the calculation of photometric redshifts by applying three different input photometry sets for our fitting procedure. For each of the five PS1 bands gP1, rP1, iP1, zP1, and yP1, we chose either the epochs minimizing the interval in observing time, the median magnitude values, or randomly drawn light curve points to compute the redshift. In addition, we derived photometric redshifts using PS1 photometry extended by GALEX/IRAC bands. Results: We find that the photometry produced by the 3π survey is sufficient to reliably detect variable sources provided that the fractional variability amplitude is at least ~3%. Considering the photometric redshifts of variable AGNs, we observe that minimizing the time spacing of the chosen points yields superior photometric redshifts in terms of the percentage of outliers (33%) and accuracy (0.07), outperforming the other two approaches. Drawing random points from the light curve gives rise to typically 57% of outliers and an accuracy of

  11. Is AGN feedback necessary to form red elliptical galaxies?

    NASA Astrophysics Data System (ADS)

    Khalatyan, A.; Cattaneo, A.; Schramm, M.; Gottlöber, S.; Steinmetz, M.; Wisotzki, L.

    2008-06-01

    We have used the smoothed particle hydrodynamics (SPH) code GADGET-2 to simulate the formation of an elliptical galaxy in a group-size cosmological dark matter halo with mass Mhalo ~= 3 × 1012h-1Msolar at z = 0. The use of a stellar population synthesis model has allowed us to compute magnitudes, colours and surface brightness profiles. We have included a model to follow the growth of a central black hole and we have compared the results of simulations with and without feedback from active galactic nuclei (AGN). We have studied the interplay between cold gas accretion and merging in the development of galactic morphologies, the link between colour and morphology evolution, the effect of AGN feedback on the photometry of early-type galaxies, the redshift evolution in the properties of quasar hosts, and the impact of AGN winds on the chemical enrichment of the intergalactic medium (IGM). We have found that the early phases of galaxy formation are driven by the accretion of cold filamentary flows, which form a disc galaxy at the centre of the dark matter halo. Disc star formation rates in this mode of galaxy growth are about as high as the peak star formation rates attained at a later epoch in galaxy mergers. When the dark matter halo is sufficiently massive to support the propagation of a stable shock, the gas in the filaments is heated to the virial temperature, cold accretion is shut down, and the star formation rate begins to decline. Mergers transform the spiral galaxy into an elliptical one, but they also reactivate star formation by bringing gas into the galaxy. Without a mechanism that removes gas from the merger remnants, the galaxy ends up with blue colours, which are atypical for its elliptical morphology. We have demonstrated that AGN feedback can solve this problem even with a fairly low heating efficiency. Our simulations support a picture where AGN feedback is important for quenching star formation in the remnant of wet mergers and for moving them to

  12. Highly-luminous Cool Core Clusters of Galaxies: Mechanically-driven or Radiatively-driven AGN?

    NASA Astrophysics Data System (ADS)

    Hlavacek-Larrondo, Julie; Fabian, Andy

    2011-12-01

    Cool core clusters of galaxies require strong feedback from their central AGN to offset cooling. We present a study of strong cool core, highly-luminous (most with Lx >= 1045 erg s-1), clusters of galaxies in which the mean central AGN jet power must be very high yet no central point X-ray source is detected. Using the unique spatial resolution of Chandra, a sample of 13 clusters is analysed, including A1835, A2204, and one of the most massive cool core clusters, RXCJ1504.1-0248. All of the central galaxies host a radio source, indicating an active nucleus, and no obvious X-ray point source. For all clusters in the sample, the nucleus has an X-ray bolometric luminosity below 2 per cent of that of the entire cluster. We investigate how these clusters can have such strong X-ray luminosities, short radiative cooling-times of the inner intracluster gas requiring strong energy feedback to counterbalance that cooling, and yet have such radiatively-inefficient cores with, on average, Lkin/Lnuc exceeding 200. Explanations of this puzzle carry significant implications for the origin and operation of jets, as well as on establishing the importance of kinetic feedback for the evolution of galaxies and their surrounding medium.

  13. Probing the innermost regions of AGN jets and their magnetic fields: LBA

    NASA Astrophysics Data System (ADS)

    Anderson, James M.; Lobanov, Andrei; Perez Torres, Miguel Angel; Ros, Eduardo; Alberdi, Antxon; Taylor, Greg; Zensus, Anton; Cawthorne, Tim; Kovalev, Yuri; Krichbaum, Thomas P.; Savolainen, Tuomas; Gomez, Jose Luis; Bach, Uwe; Bernhart, Simone; Clausen-Brown, Eric; Eilek, Jean; Fromm, Christian

    2013-10-01

    RadioAstron provides the first true full-polarization capabilities for space-VLBI. As part of our RadioAstron key science project to study magnetic fields in AGNs, we propose that the LBA participates in two global VLBI imaging observations (10 to 20 hours of total observing time) at K-band from a list of possible imaging targets (including OJ~287, 3C~273, 3C~279, and 3C~454.3 for the LBA) and sessions in the timerange 2013 October through 2014 April currently under consideration by other global VLBI stations. These measurements will exploit the unprecedented high-angular resolution polarization capabilities of RadioAstron to probe the innermost regions of AGN jets and their magnetic fields. Our initial target sample contains bright, strongly polarized AGN jets for which we confidently expect to measure polarization and be able to perform Faraday rotation synthesis analysis that will allow us to construct 3D maps of the magnetic field structure and strength in the vicinity of the central black hole. Comparison with 3D relativistic-MHD and emission simulations will allow us to obtain a better understanding of the jet formation and high-energy emission mechanisms. Perigee imaging with RadioAstron requires support from a truly global VLBI array that can co-observe for the full RadioAstron track. As very sensitive stations are required at all times to locate and track fringes to the weak RadioAstron K-band system, the LBA, including DSS-43, the ATCA, and Parkes, is crucial for the far eastern latitude region of the global array.

  14. Revealing the X-ray variability of AGN with principal component analysis

    NASA Astrophysics Data System (ADS)

    Parker, M. L.; Fabian, A. C.; Matt, G.; Koljonen, K. I. I.; Kara, E.; Alston, W.; Walton, D. J.; Marinucci, A.; Brenneman, L.; Risaliti, G.

    2015-02-01

    We analyse a sample of 26 active galactic nuclei (AGN) with deep XMM-Newton observations, using principal component analysis (PCA) to find model-independent spectra of the different variable components. In total, we identify at least 12 qualitatively different patterns of spectral variability, involving several different mechanisms, including five sources which show evidence of variable relativistic reflection (MCG-6-30-15, NGC 4051, 1H 0707-495, NGC 3516 and Mrk 766) and three which show evidence of varying partial covering neutral absorption (NGC 4395, NGC 1365 and NGC 4151). In over half of the sources studied, the variability is dominated by changes in a power-law continuum, both in terms of changes in flux and power-law index, which could be produced by propagating fluctuations within the corona. Simulations are used to find unique predictions for different physical models, and we then attempt to qualitatively match the results from the simulations to the behaviour observed in the real data. We are able to explain a large proportion of the variability in these sources using simple models of spectral variability, but more complex models may be needed for the remainder. We have begun the process of building up a library of different principal components, so that spectral variability in AGN can quickly be matched to physical processes. We show that PCA can be an extremely powerful tool for distinguishing different patterns of variability in AGN, and that it can be used effectively on the large amounts of high-quality archival data available from the current generation of X-ray telescopes. We will make our PCA code available upon request to the lead author.

  15. A NEW INFRARED COLOR CRITERION FOR THE SELECTION OF 0 < z < 7 AGNs: APPLICATION TO DEEP FIELDS AND IMPLICATIONS FOR JWST SURVEYS

    SciTech Connect

    Messias, H.; Afonso, J.; Salvato, M.; Mobasher, B.; Hopkins, A. M.

    2012-08-01

    It is widely accepted that observations at mid-infrared (mid-IR) wavelengths enable the selection of galaxies with nuclear activity, which may not be revealed even in the deepest X-ray surveys. Many mid-IR color-color criteria have been explored to accomplish this goal and tested thoroughly in the literature. Besides missing many low-luminosity active galactic nuclei (AGNs), one of the main conclusions is that, with increasing redshift, the contamination by non-active galaxies becomes significant (especially at z {approx}> 2.5). This is problematic for the study of the AGN phenomenon in the early universe, the main goal of many of the current and future deep extragalactic surveys. In this work new near- and mid-IR color diagnostics are explored, aiming for improved efficiency-better completeness and less contamination-in selecting AGNs out to very high redshifts. We restrict our study to the James Webb Space Telescope wavelength range (0.6-27 {mu}m). The criteria are created based on the predictions by state-of-the-art galaxy and AGN templates covering a wide variety of galaxy properties, and tested against control samples with deep multi-wavelength coverage (ranging from the X-rays to radio frequencies). We show that the colors K{sub s} - [4.5], [4.5] - [8.0], and [8.0] - [24] are ideal as AGN/non-AGN diagnostics at, respectively, z {approx}< 1, 1 {approx}< z {approx}< 2.5, and z {approx}> 2.5-3. However, when the source redshift is unknown, these colors should be combined. We thus develop an improved IR criterion (using K{sub s} and IRAC bands, KI) as a new alternative at z {approx}< 2.5. KI does not show improved completeness (50%-60% overall) in comparison to commonly used Infrared Array Camera (IRAC) based AGN criteria, but is less affected by non-AGN contamination (revealing a >50%-90% level of successful AGN selection). We also propose KIM (using K{sub s} , IRAC, and MIPS 24 {mu}m bands, KIM), which aims to select AGN hosts from local distances to as far

  16. STELLAR VELOCITY DISPERSION MEASUREMENTS IN HIGH-LUMINOSITY QUASAR HOSTS AND IMPLICATIONS FOR THE AGN BLACK HOLE MASS SCALE

    SciTech Connect

    Grier, C. J.; Martini, P.; Peterson, B. M.; Pogge, R. W.; Zu, Y.; Watson, L. C.; Bentz, M. C.; Dasyra, K. M.; Dietrich, M.; Ferrarese, L.

    2013-08-20

    We present new stellar velocity dispersion measurements for four luminous quasars with the Near-Infrared Integral Field Spectrometer instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8 m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole (BH) masses in luminous quasars are necessary to investigate the coevolution of BHs and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass BHs are not offset with respect to the M{sub BH}-{sigma}{sub *} relation exhibited by lower-luminosity active galactic nuclei (AGNs) with lower-mass BHs, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor (f) that places the reverberation data on the quiescent M{sub BH}-{sigma}{sub *} relation. With our updated measurements and new additions to the AGN sample, we obtain (f) = 4.31 {+-} 1.05, which is slightly lower than, but consistent with, most previous determinations.

  17. Mapping the average AGN accretion rate in the SFR-M* plane for Herschel-selected galaxies at 0 < z ≤ 2.5

    NASA Astrophysics Data System (ADS)

    Delvecchio, I.; Lutz, D.; Berta, S.; Rosario, D. J.; Zamorani, G.; Pozzi, F.; Gruppioni, C.; Vignali, C.; Brusa, M.; Cimatti, A.; Clements, D. L.; Cooray, A.; Farrah, D.; Lanzuisi, G.; Oliver, S.; Rodighiero, G.; Santini, P.; Symeonidis, M.

    2015-05-01

    We study the relation of AGN accretion, star formation rate (SFR) and stellar mass (M*) using a sample of ≈8600 star-forming galaxies up to z = 2.5 selected with Herschel imaging in the GOODS and COSMOS fields. For each of them we derive SFR and M*, both corrected, when necessary, for emission from an active galactic nucleus (AGN), through the decomposition of their spectral energy distributions (SEDs). About 10 per cent of the sample are detected individually in Chandra observations of the fields. For the rest of the sample, we stack the X-ray maps to get average X-ray properties. After subtracting the X-ray luminosity expected from star formation and correcting for nuclear obscuration, we derive the average AGN accretion rate for both detected sources and stacks, as a function of M*, SFR and redshift. The average accretion rate correlates with SFR and with M*. The dependence on SFR becomes progressively more significant at z > 0.8. This may suggest that SFR is the original driver of these correlations. We find that average AGN accretion and star formation increase in a similar fashion with offset from the star-forming `main-sequence'. Our interpretation is that accretion on to the central black hole and star formation broadly trace each other, irrespective of whether the galaxy is evolving steadily on the main-sequence or bursting.

  18. Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555

    NASA Astrophysics Data System (ADS)

    Satyapal, S.; Secrest, N. J.; Rothberg, B.; O'Connor, J. A.; Ellison, S. L.; Hickox, R. C.; Constantin, A.; Gliozzi, M.; Rosenberg, J. L.

    2016-08-01

    There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3σ level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of {L}2-10{keV}=(1.1+/- 0.4)× {10}40 erg s-1. Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of {N}{{H}}\\gt {10}24 cm-2. The hard X-ray luminosity of the putative AGN corrected for absorption is {L}2-10{keV}˜ 3× {10}42 erg s-1, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of {L}{bol}.˜ 6× {10}43-3 × 1044 {erg} {{{s}}}-1 and a lower mass limit for the black hole of {M}{BH}≃ 2× {10}6 {M}⊙ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ˜ 2.0× {10}10 {M}⊙ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  19. Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555

    NASA Astrophysics Data System (ADS)

    Satyapal, S.; Secrest, N. J.; Rothberg, B.; O’Connor, J. A.; Ellison, S. L.; Hickox, R. C.; Constantin, A.; Gliozzi, M.; Rosenberg, J. L.

    2016-08-01

    There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3σ level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of {L}2-10{keV}=(1.1+/- 0.4)× {10}40 erg s‑1. Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of {N}{{H}}\\gt {10}24 cm‑2. The hard X-ray luminosity of the putative AGN corrected for absorption is {L}2-10{keV}˜ 3× {10}42 erg s‑1, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of {L}{bol}.˜ 6× {10}43‑3 × 1044 {erg} {{{s}}}-1 and a lower mass limit for the black hole of {M}{BH}≃ 2× {10}6 {M}ȯ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ˜ 2.0× {10}10 {M}ȯ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  20. Stellar population model dependence in optical AGN identification

    NASA Astrophysics Data System (ADS)

    Chen, Yanping; Zaw, Ingyin; Farrar, Glennys

    2016-08-01

    The choice of stellar templates plays an important role in optical spectroscopic AGN classification, because the host galaxy contribution must be accurately subtracted in order to isolate the true contribution of the AGN. Up to now, simple stellar population models such as BC03, have been used as templates in doing the stellar component analysis. As more stellar population models become available, systematic study of the impact of the stellar population modeling becomes possible. This is important not only for finding the best template but also for understanding the merits and limitations of the templates. We analyzed the SDSS DR8 spectra, using different empirical, theoretical, and mixed stellar population models. We found that some templates lead to systematic biases in the identification of AGN candidates. We investigated the effects of the range of age,metallicity, and the total wavelength used in full-spectrum fitting. We found that the completeness of parameter space in the template model plays a vital role in classifying AGN candidates; the wavelength range used to analyze the spectra also affects the result but in a relative minor way. Empirical stellar models can be expected to yield the most reliable estimate of the absorption features in the host galaxies, since there will be less model dependence (e.g., on opacity assumption, line profile representation).

  1. Disc outflows and high-luminosity true type 2 AGN

    NASA Astrophysics Data System (ADS)

    Elitzur, Moshe; Netzer, Hagai

    2016-06-01

    The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such `true type 2 AGN' are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad-line emission can disappear at luminosities as high as ˜4 × 1046 erg s-1 and any Eddington ratio, though more detections can be expected at Eddington ratios below ˜1 per cent. Our results are applicable to every disc outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. While other factors, such as changes in spectral energy distribution or covering factor, can affect the intensities of broad emission lines, within this scenario they can only produce true type 2 AGN of higher luminosity then those prescribed by mass conservation.

  2. Fast Ionized X-ray Absorbers in AGNs

    NASA Astrophysics Data System (ADS)

    Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

    2015-07-01

    We present a study of X-ray ionization of MHD accretion-disk wind models in an effort to explain the highly-ionized ultra-fast outflows (UFOs) identified as X-ray absorbers recently detected in various sub-classes of Seyfert AGNs. Our primary focus is to show that magnetically-driven outflows are physically plausible candidates to account for the AGN X-ray spectroscopic observations. We calculate its X-ray ionization and the ensuing X-ray absorption line spectra in comparison with an XXM-Newton/EPIC spectrum of the narrow-line Seyfert AGN, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log(xi[erg cm/s]) = 5-6 and a hydrogen-equivalent column density on the order of 1e23 cm-2, outflowing at a sub-relativistic velocity of v/c = 0.1-0.2. The best-fit model favors its radial location at R = 200 Rs (Rs is the Schwarzschild radius), with a disk inner truncation radius at Rt = 30Rs. The overall K-shell feature in data is suggested to be dominated by Fe XXV with very little contribution from Fe XXVI 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.

  3. Review of Space VLBI RadioAstron studies of AGN

    NASA Astrophysics Data System (ADS)

    Gurvits, Leonid; Kovalev, Yuri

    2016-07-01

    Space VLBI offers an unrivalled resolution in studies of the AGN phenomena. Since 2011, the Russia-led SVLBI mission RadioAstron conducts observations at 92, 18, 6 and 1.3 cm with baselines an order of magnitude longer than the Earth diameter, therefore offering an order of magnitude "sharper" view at the brightest radio sources than achieved with Earth-based VLBI systems. In our presentation we will review the current status of the RadioAstron's scientific programme. Over the first 4.5 years of the in-orbit operations, the mission achieved successful VLBI detections of extragalactic continuum radio sources at all four observing bands. To date, detections on SVLBI baselines have been obtained for more than 150 AGN's at projected baselines up to 350 000 km (about 28 Earth diameters, ED). The highest resolution achieved is 14 microarcscends from 1.3 cm observations. RadioAstron is an international project; it conducts observations with up to 30 Earth-based radio telescopes located on different continents. We will review results of total intensity and polarisation imaging with extreme angular resolution of blazars and nearby active galaxies. We will also discuss typical and maximum brightness temperatures of blazar cores from the AGN Survey obtained with RadioAstron. Physical implications for the AGN jets formation, magnetic field and emission mechanism will be discussed on the basis of the results obtained to date.

  4. Converting the Audience: A Conversation with Agnes Wilcox

    ERIC Educational Resources Information Center

    Becker, Becky

    2006-01-01

    This article presents a conversation with Agnes Wilcox, Executive Director of Prison Performing Arts in St. Louis, Missouri, about Prison Performing Arts. Although the average person might balk at the notion of interacting with prison inmates, finding it intimidating, worrisome, or self-sacrificial, for Wilcox, Prison Performing Arts is a…

  5. Fast ionized X-ray absorbers in AGNs

    NASA Astrophysics Data System (ADS)

    Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

    2016-05-01

    We investigate the physics of the X-ray ionized absorbers often identified as warm absorbers (WAs) and ultra-fast outflows (UFOs) in Seyfert AGNs from spectroscopic studies in the context of magnetically-driven accretion-disk wind scenario. Launched and accelerated by the action of a global magnetic field anchored to an underlying accretion disk around a black hole, outflowing plasma is irradiated and ionized by an AGN radiation field characterized by its spectral energy density (SED). By numerically solving the Grad-Shafranov equation in the magnetohydrodynamic (MHD) framework, the physical property of the magnetized disk-wind is determined by a wind parameter set, which is then incorporated into radiative transfer calculations with xstar photoionization code under heating-cooling equilibrium state to compute the absorber's properties such as column density N_H, line-of-sight (LoS) velocity v, ionization parameter ξ, among others. Assuming that the wind density scales as n ∝ r-1, we calculate theoretical absorption measure distribution (AMD) for various ions seen in AGNs as well as line spectra especially for the Fe Kα absorption feature by focusing on a bright quasar PG 1211+143 as a case study and show the model's plausibility. In this note we demonstrate that the proposed MHD-driven disk-wind scenario is not only consistent with the observed X-ray data, but also help better constrain the underlying nature of the AGN environment in a close proximity to a central engine.

  6. High affinity retinoic acid receptor antagonists: analogs of AGN 193109.

    PubMed

    Johnson, A T; Wang, L; Gillett, S J; Chandraratna, R A

    1999-02-22

    A series of high affinity retinoic acid receptor (RAR) antagonists were prepared based upon the known antagonist AGN 193109 (2). Introduction of various phenyl groups revealed a preference for substitution at the para-position relative to the meta-site. Antagonists with the highest affinities for the RARs possessed hydrophobic groups, however, the presence of polar functionality was also well tolerated.

  7. Time Series Analysis of the UV Flickering in AGN

    NASA Technical Reports Server (NTRS)

    Robinson, Edward L.; Welsh, William F.

    2001-01-01

    Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability. We hoped to answer these specific questions: 1) What does the intrinsic flickering continuum spectrum look like? 2) What do the intrinsic flickering emission-line profiles look like? 3) What is the power spectrum of the flickering? 4) What is the wavelength dependence of the power spectrum? 5) Is the flickering spectrum timescale dependent? and 6) What do the high-order cross correlation functions look like? A short summary of the papers produced by this research is presented.

  8. A degeneracy in DRW modelling of AGN light curves

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-07-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time-scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light-curve modelling.

  9. The star formation and AGN luminosity relation: predictions from a semi-analytical model

    NASA Astrophysics Data System (ADS)

    Gutcke, Thales A.; Fanidakis, Nikos; Macciò, Andrea V.; Lacey, Cedric

    2015-08-01

    In a universe where active galactic nucleus (AGN) feedback regulates star formation in massive galaxies, a strong correlation between these two quantities is expected. If the gas causing star formation is also responsible for feeding the central black hole, then a positive correlation is expected. If powerful AGNs are responsible for the star formation quenching, then a negative correlation is expected. Observations so far have mainly found a mild correlation or no correlation at all [i.e. a flat relation between star formation rate (SFR) and AGN luminosity], raising questions about the whole paradigm of `AGN feedback'. In this paper, we report the predictions of the GALFORM semi-analytical model, which has a very strong coupling between AGN activity and quenching of star formation. The predicted SFR-AGN luminosity correlation appears negative in the low AGN luminosity regime, where AGN feedback acts, but becomes strongly positive in the regime of the brightest AGN. Our predictions reproduce reasonably well recent observations by Rosario et al., yet there is some discrepancy in the normalization of the correlation at low luminosities and high redshifts. Though this regime could be strongly influenced by observational biases, we argue that the disagreement could be ascribed to the fact that GALFORM neglects AGN variability effects. Interestingly, the galaxies that dominate the regime where the observations imply a weak correlation are massive early-type galaxies that are subject to AGN feedback. Nevertheless, these galaxies retain high enough molecular hydrogen contents to maintain relatively high SFRs and strong infrared emission.

  10. A radio view of high-energy emitting AGNs

    NASA Astrophysics Data System (ADS)

    Schulz, Robert Frank

    2016-07-01

    Active galactic nuclei (AGNs) are among the most energetic objects in the Universe. These galaxies that are dominated in part or even throughout the electromagnetic spectrum by emission from their central, compact region. AGNs are extensively studied by multi-wavelength observations. In the standard picture, the main driver of an AGN is a supermassive black hole (SMBH) in its centre that is surrounded by an accretion disk. Perpendicular to the disk, in the vicinity of highly magnetized SMBH relativistic outflows of plasma, so-called jets, can form on either side that can reach far beyond the host galaxy. Only about 10% of all AGNs are dominated by emission from these jets due to relativistic beaming effects and these so-called blazars dominate the extragalactic gamma-ray sky. It is commonly accepted that the low-energy emission (radio to UV/X-ray) is due to synchrotron emission from the jet. The high-energy emission is considered to stem from inverse-Compton scattering of photons on the jet particles, but different sources for these photons are discussed (internal or external to the AGN) and other models for the high-energy emission have also been proposed. The nature of the high-energy emission is strongly linked to the location of the emission region in the jet which requires a detailed understanding of the formation and evolution of jets. Radio observations especially using very long baseline interferometry (VLBI) provide the best way to gain direct information on the intrinsic properties of jets down to sub-pc scales, close to their formation region. In this thesis, I focus on the properties of three different AGNs, IC 310, PKS2004-447, and 3C 111 that belong to the small non-blazar population of gamma-ray-loud AGNs. I study them in detail with a variety of radio astronomical instruments with respect to their high-energy emission and in the context of the large monitoring programmes MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) and

  11. Understanding AGNs in the Local Universe through Optical Reverberation Mapping

    NASA Astrophysics Data System (ADS)

    Pei, Liuyi

    2016-01-01

    I present the results of observational projects aimed at measuring the mass of the black hole at the center of active galactic nuclei (AGNs) and understanding the structure and kinematics of the broad-line emitting gas within the black hole's sphere of influence.The first project aims to measure the black hole mass in the Kepler-field AGN KA1858. We obtained simultaneous spectroscopic data from the Lick Observatory 3-m telescope using the Kast Double Spectrograph and photometry data from five ground-based telescopes, and used reverberation mapping (RM) techniques to measure the emission-line light curves' lags relative to continuum variations. We obtained lags for H-beta, H-gamma, H-delta, and He II, and obtained the first black hole mass measurement for this object. Our results will serve as a reference point for future studies on relations between black hole mass and continuum variability characteristics using Kepler AGN light curves.The second project, in collaboration with the AGN STORM team, aims to understand the structure and dynamics of the broad line region (BLR) in NGC 5548 in both UV and optical wavelengths. To supplement 6 months of HST UV observations, we obtained simultaneous optical spectroscopic data from six ground-based observatories. We obtained emission-line lags for the optical H-beta and He II lines as well as velocity-resolved lag measurements for H-beta. We also compared the velocity-resolved lags for H-beta to the UV emission lines C IV and Ly-alpha and found similar lag profiles for all three lines.Finally, I will discuss my contributions to two other collaborations in AGN RM. A key component in RM is monitoring continuum variability, which is often done through ground-based photometry. I will present a pipeline that performs aperture photometry on any number of images of an AGN with WCS coordinates and immediately produces relative light curves. This pipeline enables quick looks of AGN variability in real time and has been used in the

  12. A Direct Linkage between AGN Outflows in the Narrow-line Regions and the X-Ray Emission from the Accretion Disks

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, D. W.; Wei, J. Y.

    2016-03-01

    The origin of outflow in the narrow-line region (NLR) of the active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [O iii]λ5007 line profile and the hard-X-ray (in a bandpass of 2-10 keV) emission from the central super-massive black hole (SMBH) in type-I AGNs. A sample of 47 local X-ray selected type-I AGNs at z\\lt 0.2 is extracted from the 2XMMi/SDSS-DR7 catalog, which was originally cross-matched by Pineau et al. The X-ray luminosities in an energy band from 2 to 10 keV of these luminous AGNs range from 1042 to {10}44 {erg} {{{s}}}-1. A joint spectral analysis is performed on their optical and X-ray spectra, in which the [O iii] line profile is modeled by a sum of several Gaussian functions to quantify its deviation from a pure Gaussian function. The statistics allow us to identify a moderate correlation with a significance level of 2.78σ: luminous AGNs with stronger [O iii] blue asymmetry tend to have steeper hard-X-ray spectra. By identifying the role of L/{L}{Edd} on the correlation at a 2-3σ significance level in both direct and indirect ways, we argue that the photon index versus the asymmetry correlation provides evidence that the AGN’s outflow commonly observed in its NLR is related to the accretion process occurring around the central SMBH, which favors the wind/radiation model as the origin of the outflow in luminous AGNs.

  13. Large-scale outflows in luminous QSOs revisited. The impact of beam smearing on AGN feedback efficiencies

    NASA Astrophysics Data System (ADS)

    Husemann, B.; Scharwächter, J.; Bennert, V. N.; Mainieri, V.; Woo, J.-H.; Kakkad, D.

    2016-10-01

    Context. Feedback from active galactic nuclei (AGN) is thought to play an important role in quenching star formation in galaxies. However, the efficiency with which AGN dissipate their radiative energy into the ambient medium remains strongly debated. Aims: Enormous observational efforts have been made to constrain the energetics of AGN feedback by mapping the kinematics of the ionized gas on kpc scale. We study how the observed kinematics and inferred energetics are affected by beam smearing of a bright unresolved narrow-line region (NLR) due to seeing. Methods: We re-analyse optical integral-field spectroscopy of a sample of twelve luminous unobscured quasi-stellar objects (QSOs) (0.4 AGN luminosity. This is smaller than the 5-10% feedback efficiency required by some cosmological simulations to reproduce the massive galaxy population. The injected momentum fluxes are close or below the simple radiation-pressure limit Lbol/c for the conical outflow model for the NLR and ENLR

  14. Dependence of the broad Fe Kα line on the physical parameters of AGN

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Yuan, Weimin; Lu, Youjun; Carrera, Francisco J.; Falocco, Serena; Dong, Xiao-Bo

    2016-08-01

    In this paper, the dependence of the broad Fe Kα line on the physical parameters of AGN, such as the black hole mass MBH, accretion rate (equivalently represented by Eddington ratio λEdd), and optical classification, is investigated by applying the X-ray spectra stacking method to a large sample of AGN which have well measured optical parameters. A broad line feature is detected (>3σ) in the stacked spectra of the high λEdd sub-sample (log λEdd > -0.9). The profile of the broad line can be well fitted with relativistic broad line model, with the line energy consistent with highly ionized Fe Kα line (i.e. Fe XXVI). A model consisting of multiple narrow lines cannot be ruled out, however. We found hints that the Fe K line becomes broader as the λEdd increases. No broad line feature is shown in the sub-sample of broad-line Seyfert 1 (BLS1) galaxies and in the full sample, while a broad line might be present, though at low significance, in the sub-sample of narrow-line Seyfert 1 (NLS1) galaxies. We find no strong dependence of the broad line on black hole masses. Our results indicate that the detection/properties of the broad Fe Kα line may strongly depend on λEdd, which can be explained if the ionization state and/or truncation radius of the accretion disc changes with λEdd. The non-detection of the broad line in the BLS1 sub-sample can be explained if the the average EW of the relativistic Fe Kα line is weak or/and the fraction of sources with relativistic Fe Kα line is small in BLS1 galaxies.

  15. Dependence of the broad Fe Kα line on the physical parameters of AGN

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Yuan, Weimin; Lu, Youjun; Carrera, Francisco J.; Falocco, Serena; Dong, Xiao-Bo

    2016-11-01

    In this paper, the dependence of the broad Fe Kα line on the physical parameters of AGN, such as the black hole mass MBH, accretion rate (equivalently represented by Eddington ratio λEdd) and optical classification is investigated by applying the X-ray spectra stacking method to a large sample of AGN which have well measured optical parameters. A broad-line feature is detected (>3σ) in the stacked spectra of the high λEdd sub-sample (log λEdd > -0.9). The profile of the broad line can be well fitted with relativistic broad-line model, with the line energy consistent with highly ionized Fe Kα line (i.e. Fe XXVI). A model consisting of multiple narrow lines cannot be ruled out, however. We found hints that the Fe K line becomes broader as the λEdd increases. No broad-line feature is shown in the sub-sample of broad-line Seyfert 1 (BLS1) galaxies and in the full sample, while a broad line might be present, though at low significance, in the sub-sample of narrow-line Seyfert 1 (NLS1) galaxies. We find no strong dependence of the broad line on black hole masses. Our results indicate that the detection/properties of the broad Fe Kα line may strongly depend on λEdd, which can be explained if the ionization state and/or truncation radius of the accretion disc changes with λEdd. The non-detection of the broad line in the BLS1 sub-sample can be explained if the average equivalent width of the relativistic Fe Kα line is weak or/and the fraction of sources with relativistic Fe Kα line is small in BLS1 galaxies.

  16. THE LICK AGN MONITORING PROJECT: RECALIBRATING SINGLE-EPOCH VIRIAL BLACK HOLE MASS ESTIMATES

    SciTech Connect

    Park, Daeseong; Woo, Jong-Hak; Treu, Tommaso; Bennert, Vardha N.; Barth, Aaron J.; Walsh, Jonelle; Bentz, Misty C.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor; Greene, Jenny E.; Malkan, Matthew A.

    2012-03-01

    We investigate the calibration and uncertainties of black hole (BH) mass estimates based on the single-epoch (SE) method, using homogeneous and high-quality multi-epoch spectra obtained by the Lick Active Galactic Nucleus (AGN) Monitoring Project for nine local Seyfert 1 galaxies with BH masses <10{sup 8} M{sub Sun }. By decomposing the spectra into their AGNs and stellar components, we study the variability of the SE H{beta} line width (full width at half-maximum intensity, FWHM{sub H{beta}} or dispersion, {sigma}{sub H{beta}}) and of the AGN continuum luminosity at 5100 A (L{sub 5100}). From the distribution of the 'virial products' ({proportional_to} FWHM{sub H{beta}}{sup 2} L{sup 0.5}{sub 5100} or {sigma}{sub H{beta}}{sup 2} L{sup 0.5}{sub 5100}) measured from SE spectra, we estimate the uncertainty due to the combined variability as {approx}0.05 dex (12%). This is subdominant with respect to the total uncertainty in SE mass estimates, which is dominated by uncertainties in the size-luminosity relation and virial coefficient, and is estimated to be {approx}0.46 dex (factor of {approx}3). By comparing the H{beta} line profile of the SE, mean, and root-mean-square (rms) spectra, we find that the H{beta} line is broader in the mean (and SE) spectra than in the rms spectra by {approx}0.1 dex (25%) for our sample with FWHM{sub H{beta}} <3000 km s{sup -1}. This result is at variance with larger mass BHs where the difference is typically found to be much less than 0.1 dex. To correct for this systematic difference of the H{beta} line profile, we introduce a line-width dependent virial factor, resulting in a recalibration of SE BH mass estimators for low-mass AGNs.

  17. THE LICK AGN MONITORING PROJECT: REVERBERATION MAPPING OF OPTICAL HYDROGEN AND HELIUM RECOMBINATION LINES

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Thornton, Carol E.; Yoshii, Yuzuru; Sakata, Yu; Minezaki, Takeo; Woo, Jong-Hak; Malkan, Matthew A.; Wang, Xiaofeng; Steele, Thea N.; Silverman, Jeffrey M.; Serduke, Frank J. D.; Li, Weidong; Lee, Nicholas; Treu, Tommaso; Street, Rachel A.; Hidas, Marton G.; Hiner, Kyle D.; Greene, Jenny E.

    2010-06-20

    We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range {approx}10{sup 6}-10{sup 7} M{sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad H{beta} emission, which we have previously reported. We present here the light curves for the H{alpha}, H{gamma}, He II {lambda}4686, and He I {lambda}5876 emission lines and the time lags for the emission-line responses relative to changes in the continuum flux. Combining each emission-line time lag with the measured width of the line in the variable part of the spectrum, we determine a virial mass of the central supermassive black hole from several independent emission lines. We find that the masses are generally consistent within the uncertainties. The time-lag response as a function of velocity across the Balmer line profiles is examined for six of the AGNs. We find similar responses across all three Balmer lines for Arp 151, which shows a strongly asymmetric profile, and for SBS 1116+583A and NGC 6814, which show a symmetric response about zero velocity. For the other three AGNs, the data quality is somewhat lower and the velocity-resolved time-lag response is less clear. Finally, we compare several trends seen in the data set against the predictions from photoionization calculations as presented by Korista and Goad. We confirm several of their predictions, including an increase in responsivity and a decrease in the mean time lag as the excitation and ionization level for the species increases. Specifically, we find the time lags of the optical

  18. Optical-to-X-ray emission in low-absorption AGN: results from the Swift-BAT 9-month catalogue

    NASA Astrophysics Data System (ADS)

    Vasudevan, R. V.; Mushotzky, R. F.; Winter, L. M.; Fabian, A. C.

    2009-11-01

    We present simultaneous optical-to-X-ray spectral energy distributions (SEDs) from Swift's X-ray and UV-optical telescopes (XRTs and UVOTs) for a well-selected sample of 26 low-redshift (z < 0.1) active galactic nuclei (AGN) from the Swift/Burst Alert Telescope 9-month catalogue, the largest well-studied, hard X-ray-selected survey of local AGN to date. Our sub-sample consists of AGN with low intrinsic X-ray absorption (NH < 1022cm-2) and minimal spectral complexity, to more accurately recover the intrinsic accretion luminosity in these sources. We perform a correction for host galaxy contamination in all available UVOT filter images to recover the intrinsic AGN emission and estimate intrinsic dust extinction from the resultant nuclear SEDs. Black hole mass estimates are determined from the host galaxy Two-Micron All-Sky Survey K-band bulge luminosity. Accretion rates determined from our SEDs are on average low (Eddington ratios λEdd <~ 0.1) and hard X-ray bolometric corrections cluster at ~10-20, in contrast with the higher values seen for quasars. An average SED for the 22 low accretion rate (λEdd < 0.1) objects is presented, with and without correction for extinction. Significant dust reddening is found in some objects despite the selection of low NH objects, emphasizing the complex relationship between these two types of absorption. We do not find a correlation of the optical-to-X-ray spectral index with the Eddington ratio, regardless of the optical reference wavelength chosen for defining the spectral index. An anticorrelation of bolometric correction with black hole mass may reinforce `cosmic downsizing' scenarios, since the higher bolometric corrections at low mass would boost accretion rates in local, lower mass black holes. We also perform a basic analysis of the UVOT-derived host galaxy colours for our sample and find hosts cluster near the `green valley' of the colour-magnitude diagram, but better quality images are needed for a more definitive

  19. Emission-Line Taxonomy and the Nature of AGN-Looking Galaxies in the SDSS

    NASA Astrophysics Data System (ADS)

    Cid Fernandes, Roberto; Stasińska, Grażyna; Vale Asari, Natalia; Mateus, Abílio; Schlickmann, Marielli S.; Schoenell, William; Schoenell

    2010-05-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission-line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separetely because one cannot fully classify them onto the standard star-forming, Seyfert, or LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to explain their line ratios and luminosities. Such retired galaxies deserve a place in the emission-line taxonomy.

  20. The unification of powerful radio-loud AGN: the multi-wavelength balance

    NASA Astrophysics Data System (ADS)

    Podigachoski, Pece; Barthel, Peter; Haas, Martin; Leipski, Christian; Wilkes, Belinda; Rocca-Volmerange, Brigitte; Drouart, Guillaume

    2016-08-01

    Powerful radio-loud AGN, by virtue of their optically-thin low-frequency radio emission, represent unique targets in orientation-based unification studies, and in searches for orientation indicators and orientation invariants. Central in these efforts is the landmark Third Cambridge Catalog of Radio Sources (3CR), a sample which has been observed with most ground- and space-based telescopes over much of the electromagnetic spectrum. Using mainly Herschel and Spitzer photometric data, we recently studied the full infrared spectral energy distributions of the complete sample of 3CR radio sources at redshifts z>1. We found that the radio-loud quasars (QSRs, Type 1) and the radio galaxies (RGs, Type 2) have completely different mid-infrared, but remarkably similar far-infrared colors. These findings are in line with the view that powerful QSRs and RGs belong to the same parent population and support previously reported findings in other wavelength domains.

  1. Tyramine antagonistic properties of AGN 1135, an irreversible inhibitor of monoamine oxidase type B.

    PubMed

    Finberg, J P; Tenne, M; Youdim, M B

    1981-05-01

    1 The effects of the irreversible monoamine oxidase (MAO) inhibitors, AGN 1133, AGN 1135 and (-)-deprenyl, on tyramine and noradrenaline responses and uptake of [3H]-metaraminol were investigated in the isolated vas deferens of the rat. Uptake of [3H]-metaraminol and [3H]-octopamine was compared in mouse vas deferens. The modification of tyramine and noradrenaline-induced pressor responses by AGN 1133 and AGN 1135 was examined in anaesthetized rats and cats. 2 AGN 1133 (7.5 x 10(-6)M) greatly potentiated responses to tyramine in the rat isolated vas deferens. Both AGN 1135 and (-)-deprenyl inhibited tyramine responses selectively at concentrations above 10(-5)M (which caused almost complete inhibition of MAO types A and B) but tyramine responses were potentiated on washing out the inhibitors. 3 AGN 1135 (10(-4)M) and (-)-deprenyl (10-5)M) inhibited [3H]-metaraminol uptake by about 20% in rat and mouse vas deferens; neither inhibitor affected [3H]-octopamine uptake in mouse vas deferens. Desmethylimipramine (10(-6)M) inhibited amine uptake by more than 70%. 4 AGN 1133 (1.5 mg/kg) potentiated pressor responses to tyramine in rats and cats whereas AGN 1135 (1.5 mg/kg) did not. 5 AGN 1135 possesses tyramine antagonistic activity which is qualitatively similar to that of (-)-deprenyl but which cannot satisfactorily be explained by inhibition of neuronal or granula amine uptake.

  2. AGN feedback in the nucleus of M 51

    NASA Astrophysics Data System (ADS)

    Querejeta, M.; Schinnerer, E.; García-Burillo, S.; Bigiel, F.; Blanc, G. A.; Colombo, D.; Hughes, A.; Kreckel, K.; Leroy, A. K.; Meidt, S. E.; Meier, D. S.; Pety, J.; Sliwa, K.

    2016-10-01

    AGN feedback is invoked as one of the most relevant mechanisms that shape the evolution of galaxies. Our goal is to understand the interplay between AGN feedback and the interstellar medium in M 51, a nearby spiral galaxy with a modest AGN and a kpc-scale radio jet expanding through the disc of the galaxy. For this purpose, we combine molecular gas observations in the CO(1-0) and HCN(1-0) lines from the Plateau de Bure interferometer with archival radio, X-ray, and optical data. We show that there is a significant scarcity of CO emission in the ionisation cone, while molecular gas emission tends to accumulate towards the edges of the cone. The distribution and kinematics of CO and HCN line emission reveal AGN feedback effects out to r ~ 500 pc, covering the whole extent of the radio jet, with complex kinematics in the molecular gas which displays strong local variations. We propose that this is the result of the almost coplanar jet pushing on molecular gas in different directions as it expands; the effects are more pronounced in HCN than in CO emission, probably as the result of radiative shocks. Following previous interpretation of the redshifted molecular line in the central 5'' as caused by a molecular outflow, we estimate the outflow rates to be ṀH2 ~ 0.9 M⊙/ yr and Ṁdense ~ 0.6 M⊙/ yr, which are comparable to the molecular inflow rates (~1 M⊙/ yr); gas inflow and AGN feedback could be mutually regulated processes. The agreement with findings in other nearby radio galaxies suggests that this is not an isolated case, and is probably the paradigm of AGN feedback through radio jets, at least for galaxies hosting low-luminosity active nuclei. The reduced HCN(1-0) datacube is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A118

  3. Comparison of spatial and angular clustering of X-ray AGN

    NASA Astrophysics Data System (ADS)

    Koutoulidis, L.; Plionis, M.; Georgantopoulos, I.; Georgakakis, A.; Akylas, A.; Basilakos, S.; Mountrichas, G.

    2016-05-01

    The angular correlation function is a powerful tool for deriving the clustering properties of active galactic nuclei (AGN) and hence the mass of the corresponding dark matter halos in which they reside. However, recent studies based on the application of the angular correlation function on X-ray samples, yield results that are apparently inconsistent with those based on the direct estimation of the spatial correlation function. The goal of the present paper is to attempt to investigate this issue by analysing a well-defined sample. To this end we use the hard-band (2-10 keV) X-ray selected sources of the Chandra AEGIS fields, chosen because of the availability of accurately derived flux sensitivity maps. In particular we use the 186 hard-band sources with spectroscopic redshifts in the range z = 0.3-1.3, a range selected in order to contain the bulk of the AGN while minimizing the contribution of unknown clustering and luminosity evolution from very high redshifts. Using the projected spatial auto-correlation function, we derive a comoving clustering length of x0 = 5.4 ± 1.0h-1 Mpc (for γ = 1.8), which is consistent with results in the literature. We further derive the angular correlation function and corresponding spatial clustering length using the Limber's inversion equation and a novel parametrization of the clustering evolution model that also takes the bias evolution of the host dark matter halo into account. The Limber's inverted spatial comoving clustering length of x0 = 5.5 ± 1.2h-1 Mpc at a median redshift of z ≃ 0.75 matches the clustering length that is directly measured from the spatial correlation function analysis, but after introducing a significant non-linear contribution to the growing mode of perturbations; this contribution is estimated independently from literature results of x0 at different redshifts. Therefore, using this sample of hard X-ray AGN and our clustering evolution parametrization, we find an excellent consistency between the

  4. Quenching Star Formation: Can AGN Do the Trick?

    NASA Astrophysics Data System (ADS)

    Gabor, Jared M.; Davé, Romeel

    2009-12-01

    We post-process galaxy star formation histories in cosmological hydrodynamics simulations to test quenching mechanisms associated with AGN. By comparing simulation results to color-magnitude diagrams and luminosity functions of SDSS galaxies, we examine whether ``quasar mode'' or ``radio mode'' AGN feedback can yield a realistic red sequence. Both cases yield red sequences distinct from the blue cloud, decent matches to the luminosity function, and galaxies that are too blue by about 0.1 magnitudes in g-r. Our merger-based prescription for quasar mode feedback, however, yields a red sequence build-up inconsistent with observations: the luminosity function lacks a characteristic knee, and the brightest galaxies include a small number of young stars.

  5. The AGN Population and the Cosmic X-ray Background

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, C. Meg; Schawinski, Kevin

    2015-08-01

    In order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (Lx~1044 erg/s) sources (Seyfert-type AGN), at z~0.5-1 and in heavily obscured but Compton-thin, NH~1023 cm-2, systems.However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. Using a combination of X-ray stacking and multi wavelength selection techniques we constrain the amount of black hole accretion as a function of cosmic history, from z~0 to z~6. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations.We finally investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~0 to z~3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth.

  6. Observational aspects of AGN jets at high energy

    NASA Astrophysics Data System (ADS)

    Kataoka, Jun

    2015-03-01

    For the last two decades, significant and dramatic progress has been made in understanding astrophysical jet sources, particularly in the X-ray and gamma-ray energy bands. For example, the Chandra X-ray observatory reveals a number of AGN jets extending from kpc to Mpc scales. More recently, the Fermi Gamma-ray Space Telescopes launched in 2008 started monitoring the gamma-ray sky with excellent sensitivity of about ten times greater than that of EGRET onboard CGRO, and has detected more than 2,000 sources (mostly AGNs) as of 2014. Moreover, Fermi-LAT has discovered gamma-ray emissions not only from blazars but from a dozen radio galaxies not previously known to emit gamma-rays. Closer to home, the Fermi-bubbles were discovered to extend 50 degrees above and below the Galactic center. These large scale diffuse gamma-ray structures are similar in structure to AGN lobes such as those seen in Cen A and provide evidence for past activity in our Galactic center. In this review, I will first summarize recent highlights of large scale jets in radio galaxies, specifically resolved by the Chandra X-ray observatory. Next I will move on to the gamma-ray sky to present some highlights from Fermi-LAT observations of ``misaligned'' blazars, namely radio galaxies. I will discuss a unification scheme connecting blazars and misaligned radio galaxies. In the last part, I will also briefly comment on recent multiband observations of the Fermi-bubble and possible impacts on the AGN jet physics in the near future.

  7. Why and when is internally driven AGN feedback energetically favoured?

    NASA Astrophysics Data System (ADS)

    Pope, Edward C. D.

    2012-11-01

    Active galactic nucleus (AGN) outflows are the heat given up when gas in a galaxy evolves towards thermodynamic equilibrium. Indeed, while AGN feedback regulates the growth of massive galaxies, its origin can be understood as the spontaneous thermodynamic process which ensures that the (Gibbs) free energy of the system always decreases, enabling the galaxy to reach a more energetically favourable state. In particular, it is shown that feedback heating processes will be favoured whenever the hot atmosphere of a galaxy would effectively gain energy as a result of cooling. For example, as the hot atmosphere of a galaxy cools and contracts, the work done by gravity will be thermalized, with a fraction of the gas also being captured by stars and the supermassive black hole at the centre of the galaxy. If this gain of energy exceeds the loss of energy that occurs when cooling gas drops out of the atmosphere, the Gibbs free energy of the system would increase overall. Since this is energetically unfavourable, feedback heating is initiated which acts to reduce the net cooling rate of the atmosphere, thereby preventing any build-up of energy. The Gibbs free energy can also decrease in the absence of feedback heating, but only if the loss of energy due to mass dropping out of the atmosphere exceeds the gains of energy described above. Therefore, to ensure that the Gibbs free energy always decreases, a galaxy will necessarily flip between these two states, experiencing episodes of heating and cooling. Due to the close long-term balance between heating and cooling, the gas in a galaxy will evolve quasistatically towards thermodynamic equilibrium, which has the observable appearance of galaxy growth being regulated by AGN feedback. The same mechanism also provides an explanation for why strong AGN feedback occurs more frequently in cool-core galaxy clusters than in non-cool-core clusters.

  8. HST Imaging of Giant Ionized Clouds Around Fading AGN

    NASA Astrophysics Data System (ADS)

    Keel, William C.; Maksym, W. P.; Bennert, V.; Schawinski, K.; Lintott, C. J.; Chojnowski, D.

    2013-01-01

    We present HST images in [O III], Hα, and adjacent continuum bands, for 7 AGN surrounding by photoionized clouds extending 10-35 kpc from the nuclei, whose energy budgets suggest substantial fading over timescales 30,000-100,000 years. These targets were found as a result of the efforts of nearly 200 Galaxy Zoo volunteers in both targeted and serendipitous searches, aimed at finding objects similar to Hanny's Voorwerp near IC 2497. The images reveal a fascinating variety of emission-line structures. Sub-kpc loops near the nuclei are frequent. A larger 5-kpc ring of emission appears near one AGN, not obviously connected to the gas near the nucleus. In NGC 5972, two systems of gas and dust appear, in a pattern suggesting that they result from a merger; there is a gap in line emission around the nucleus which would fit with a rapid cutoff in ionizing luminosity. Some of these clouds have their emission concentrated in very narrow filaments kiloparsecs in length, which might suggest a role for extensive magnetic fields. As in Hanny's Voorwerp, we see little spatial correlation between ionization parameter and Hα surface brightness, indicating that there is substantial density structure on yet-unresolved scales. The two AGN with large double radio sources show extended line emission perpendicular to the radio axis, violating a common pattern, as if the AGN axis had recently and rapidly precessed by ~90 degrees. This, plus the common signs of recent interaction in the hosts, informs our speculations on what might drive a rapid switch in the mode of energy output from accretion into the black holes in these objects, from radiative to kinetic, including the possibility that a special epoch near the merger of a binary black hole might be involved. This work has been supported by NASA through STSCI grant GO-12525.01.

  9. Very high energy gamma ray observations of southern hemisphere AGNs

    NASA Astrophysics Data System (ADS)

    Chadwick, P. M.; Lyons, K.; McComb, T. J. L.; Orford, K. J.; Osborne, J. L.; Rayner, S. M.; Shaw, S. E.; Turver, K. E.

    2001-12-01

    A range of AGNs visible from the Southern hemisphere has been observed with the University of Durham Mark 6 very high energy gamma ray telescope. Results of observations of 1ES 0323+022, PKS 0829+046, 1ES 1101-232, Cen A, PKS 1514-24, RKJ 10578-275, 1ES 2316-423, PKS 2005-489 and PKS 0548-322 are presented. .

  10. Broadband, radio spectro-polarimetric observations of radiative-mode and jet-mode AGN

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Shane P.; Purcell, C. R.; Farnes, J. S.; Sun, X. H.; Anderson, C. S.; Gaensler, B. M.

    2016-08-01

    Observations of polarised synchrotron emission from radio-loud AGN, along with the associated Faraday rotation, provides a highly sensitive probe of magneto-ionic material in AGN environments. Here we present the results from our investigation of the environments of two broad classes of radio-loud AGN (radiative-mode & jet mode) using broadband radio spectro-polarimetry, from 1 to 10 GHz. By spectrally resolving the spatial unresolved polarised emission, we directly probe the different magneto-ionic environments of radiative-mode and jet-mode AGN. We also present results for the dependence of the polarisation and Faraday rotation properties of the two AGN types based on the number of polarised emission components, the spectral index, and the intrinsic magnetic field structure. Finally, we outline the prospects for future Faraday rotation studies of radio-loud AGN with the Australian SKA Pathfinder telescope, and present some preliminary results from the early science observations.

  11. Triggering star formation by both radiative and mechanical AGN feedback

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Gan, Zhao-Ming; Xie, Fu-Guo

    2013-08-01

    We perform two dimensional hydrodynamic numerical simulations to study the positive active galactic nucleus (AGN) feedback which triggers, rather than suppresses, star formation. Recently, it was shown by Nayakshin et al. and Ishibashi et al. that star formation occurs when the cold interstellar medium (ISM) is squeezed by the impact of mass outflow or radiation pressure, respectively. Mass outflow is ubiquitous in this astrophysical context, and radiation pressure is also important if the AGN is luminous. For the first time in this subject, we incorporate both mass outflow feedback and radiative feedback into our model. Consequently, the ISM is shocked into shells by the AGN feedback, and these shells soon fragment into clumps and filaments because of Rayleigh-Taylor and thermal instabilities. We have two major findings: (1) the star formation rate can indeed be very large in the clumps and filaments. However, the resultant star formation rate density is too large compared with previous works, which is mainly because we ignore the fact that most of the stars that are formed would be disrupted when they move away from the galactic center. (2) Although radiation pressure feedback has a limited effect, when mass outflow feedback is also included, they reinforce each other. Specifically, in the gas-poor case, mass outflow is always the dominant contributor to feedback.

  12. Cosmic Ray Generation by Massive Binary Black Hole in AGN

    NASA Astrophysics Data System (ADS)

    Dokuchaev, Vyacheslav I.

    A model of nonstationary giant bow shocks produced by a supersonic orbital motion of a gravitationally bound massive binary black hole in the dense and highly inhomegeneous environment of the central Broad line Region (BLR) of AGN is proposed. The environment necessary for shocks generation is provided by numerous short-living clouds of dense plasma which are continuously reproduced by destructive collissions of fast moving stars in a very compact central stellar cluster of AGN. Some part of the gravitational energy of supersonically orbiting massive binary black hole transforms into the shock wave and then into the broad -range electromagnetic radiation up to the high -energy gamma radiation and the energetic cosmic ray particles. The orbit of a binary is evolutionary contracting due to a frictional drag in a dense plasma until the gravitational radiation becomes more influential. The model provide also the suitable conditions for the acceleration of cosmic ray protons up to the ultra-high energies under the realistic parameters of a massive binary black hole and the BLR in AGN.

  13. Prevention of MPTP-induced neurotoxicity by AGN-1133 and AGN-1135, selective inhibitors of monoamine oxidase-B.

    PubMed

    Heikkila, R E; Duvoisin, R C; Finberg, J P; Youdim, M B

    1985-10-22

    Two selective and potent inhibitors of monoamine oxidase (MAO) type B, namely AGN-1133 (N-methyl-N-propynyl-1-indanamine) and AGN-1135 (N-propynyl-1-indanamine), given to mice prior to the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) protected against the neurotoxic effects of MPTP. For example, mice treated with these agents prior to MPTP, did not exhibit the decrement in the neostriatal content of dopamine and its metabolites normally seen after MPTP administration. These data lend further support to the concept that the oxidation of MPTP by MAO-B to its corresponding pyridinium analog, 1-methyl-4-phenyl-pyridinium (MPP+) is an important feature of the neurotoxic process.

  14. Cycling of the powerful AGN in MS 0735.6+7421 and the duty cycle of radio AGN in clusters

    NASA Astrophysics Data System (ADS)

    Vantyghem, A. N.; McNamara, B. R.; Russell, H. R.; Main, R. A.; Nulsen, P. E. J.; Wise, M. W.; Hoekstra, H.; Gitti, M.

    2014-08-01

    We present an analysis of deep Chandra X-ray observations of the galaxy cluster MS 0735.6+7421, which hosts the most energetic radio active galactic nucleus (AGN) known. Our analysis has revealed two cavities in its hot atmosphere with diameters of 200-240 kpc. The total cavity enthalpy, mean age, and mean jet power are 9 × 1061 erg, 1.6 × 108 yr, and 1.7 × 1046 erg s-1, respectively. The cavities are surrounded by nearly continuous temperature and surface brightness discontinuities associated with an elliptical shock front of Mach number 1.26 (1.17-1.30) and age of 1.1 × 108 yr. The shock has injected at least 4 × 1061 erg into the hot atmosphere at a rate of 1.1 × 1046 erg s-1. A second pair of cavities and possibly a second shock front are located along the radio jets, indicating that the AGN power has declined by a factor of 30 over the past 100 Myr. The multiphase atmosphere surrounding the central galaxy is cooling at a rate of 40 M⊙yr-1, but does not fuel star formation at an appreciable rate. In addition to heating, entrainment in the radio jet may be depleting the nucleus of fuel and preventing gas from condensing out of the intracluster medium. Finally, we examine the mean time intervals between AGN outbursts in systems with multiple generations of X-ray cavities. We find that, like MS0735, their AGN rejuvenate on a time-scale that is approximately 1/3 of their mean central cooling time-scales, indicating that jet heating is outpacing cooling in these systems.

  15. VizieR Online Data Catalog: Gamma-ray AGN type determination (Hassan+, 2013)

    NASA Astrophysics Data System (ADS)

    Hassan, T.; Mirabal, N.; Contreras, J. L.; Oya, I.

    2013-11-01

    In this paper, we employ Support Vector Machines (SVMs) and Random Forest (RF) that embody two of the most robust supervised learning algorithms available today. We are interested in building classifiers that can distinguish between two AGN classes: BL Lacs and FSRQs. In the 2FGL, there is a total set of 1074 identified/associated AGN objects with the following labels: 'bzb' (BL Lacs), 'bzq' (FSRQs), 'agn' (other non-blazar AGN) and 'agu' (active galaxies of uncertain type). From this global set, we group the identified/associated blazars ('bzb' and 'bzq' labels) as the training/testing set of our algorithms. (2 data files).

  16. Pan-STARRS1 variability of XMM-COSMOS AGN. II. Physical correlations and power spectrum analysis

    NASA Astrophysics Data System (ADS)

    Simm, T.; Salvato, M.; Saglia, R.; Ponti, G.; Lanzuisi, G.; Trakhtenbrot, B.; Nandra, K.; Bender, R.

    2016-01-01

    Aims: The goal of this work is to better understand the correlations between the rest-frame UV/optical variability amplitude of quasi-stellar objects (QSOs) and physical quantities such as redshift, luminosity, black hole mass, and Eddington ratio. Previous analyses of the same type found evidence for correlations between the variability amplitude and these active galactic nucleus (AGN) parameters. However, most of the relations exhibit considerable scatter, and the trends obtained by various authors are often contradictory. Moreover, the shape of the optical power spectral density (PSD) is currently available for only a handful of objects. Methods: We searched for scaling relations between the fundamental AGN parameters and rest-frame UV/optical variability properties for a sample of ~90 X-ray selected AGNs covering a wide redshift range from the XMM-COSMOS survey, with optical light curves in four bands (gP1, rP1, iP1, zP1) provided by the Pan-STARRS1 (PS1) Medium Deep Field 04 survey. To estimate the variability amplitude, we used the normalized excess variance (σ2rms) and probed variability on rest-frame timescales of several months and years by calculating σ2rms from different parts of our light curves. In addition, we derived the rest-frame optical PSD for our sources using continuous-time autoregressive moving average (CARMA) models. Results: We observe that the excess variance and the PSD amplitude are strongly anticorrelated with wavelength, bolometric luminosity, and Eddington ratio. There is no evidence for a dependency of the variability amplitude on black hole mass and redshift. These results suggest that the accretion rate is the fundamental physical quantity determining the rest-frame UV/optical variability amplitude of quasars on timescales of months and years. The optical PSD of all of our sources is consistent with a broken power law showing a characteristic bend at rest-frame timescales ranging between ~100 and ~300 days. The break timescale

  17. THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Cool, Richard J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Brown, Michael J. I.; Caldwell, Nelson; Forman, William R.; Hickox, Ryan C.; Jones, Christine; Murray, Stephen S.; Dey, Arjun; Jannuzi, Buell T.; Moustakas, John

    2012-03-20

    We present the galaxy optical luminosity function for the redshift range 0.05 < z < 0.75 from the AGN and Galaxy Evolution Survey, a spectroscopic survey of 7.6 deg{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z){sup (0.54{+-}0.64)} for red galaxies and (1 + z){sup (1.64{+-}0.39)} for blue galaxies.

  18. AGN jets under the microscope: A divide? Doctoral Thesis Award Lecture 2011

    NASA Astrophysics Data System (ADS)

    Karouzos, M.; Britzen, S.; Witzel, A.; Zensus, A. J.; Eckart, A.

    2012-06-01

    A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non-radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio-loud flat-spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat-spectrum radio-quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat-spectrum radio-quasars. This is interpreted as evidence for helically structured jets.

  19. Cosmic Evolution of Accretion Power and Fusion Power: AGN and Starbursts at High Redshifts

    NASA Astrophysics Data System (ADS)

    Arnold Malkan, Matthew

    2009-05-01

    Extragalactic astronomers have been working for decades on obtaining robust measures of the luminosities galaxies produce from stars, and from active galactic nuclei. Our ultimate goal is deriving the cosmic evolution of all radiation produced by fusion and by black hole accretion. The combined effects of dust reddening and redshift make it impossible to achieve this with optical observations alone. Fortunately, infrared thermal continuum and forbidden line emission--from warm dust grains and ionized gas, respectively--can now be measured with excellent sensitivity. However, when measuring entire galaxies, these dust and gas emissions are powered by both active galactic nuclei and starbursts, which may be hard to separate spatially. We must use the fact that the patterns of IR energy output from AGN and SBs differ, with AGN making more ionized gas and hotter dust grains. Low-resolution spectroscopy, or even narrow-band filters can sort out the line emission from both processes when they are mixed in the same galaxy. The hope is that these spectroscopic determinations of star formation rate, and mass accretion rate in relatively small samples of bright galaxies will allow a calibration of broadband continuum measures. The dust continuum emission will then be measured in enormous samples of galaxies spanning their full range of masses, metallicities, environments and redshifts. Along the way, we should learn the astrophysical basis of black hole/galaxy "co-evolution." I will summarize some of the first specific infrared steps of this ambitious agenda, taken with IRAS and ISO to 2MASS, Akari and Spitzer and other telescopes. Time permitting, some of the exciting upcoming observational prospects will be advertised.

  20. Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe

    NASA Astrophysics Data System (ADS)

    Giallongo, E.; Grazian, A.; Fiore, F.; Fontana, A.; Pentericci, L.; Vanzella, E.; Dickinson, M.; Kocevski, D.; Castellano, M.; Cristiani, S.; Ferguson, H.; Finkelstein, S.; Grogin, N.; Hathi, N.; Koekemoer, A. M.; Newman, J. A.; Salvato, M.

    2015-06-01

    Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4-6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe. Aims: In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer, and various ground-based telescopes. Methods: We have adopted a relatively novel criterion. As a first step, high redshift galaxies are selected in the NIR H band down to very faint levels (H ≤ 27) using reliable photometric redshifts. At z> 4 this corresponds to a selection criterion based on the galaxy rest-frame UV flux. AGN candidates are then picked up from this parent sample if they show X-ray fluxes above a threshold of FX ˜ 1.5 × 10-17 erg cm-2 s-1 (0.5-2 keV), corresponding to a probability of spurious detections of 2 × 10-4 in the deep X-ray 4 Ms Chandra image. Results: We have found 22 AGN candidates at z> 4 and we have derived the first estimate of the UV luminosity function in the redshift interval 4 AGN host galaxies. Both effects could, in principle, significantly reduce the estimated average volume densities and/or ionizing emissivities, especially at the highest

  1. Constraints on Feedback in the Local Universe: The Relation Between Star Formation and AGN Activity in Early Type Galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher P.; Baum, Stefi Alison

    2016-01-01

    We address the relation between star formation and AGN activity in a sample of 231 nearby (0.0002 < z < 0.0358) early type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR and radio. Our results indicate that early type galaxies in the current epoch are rarely powerful AGNs, with P < 1022 WHz-1 for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The SFR of these galaxies is less than 0.1 M⊙yr-1. They also tend to be radio faint (P < 1022 WHz-1). There is a nearly equal fraction of star forming galaxies in radio faint (P < 1022 WHz-1) and radio bright galaxies (P ≥ 1022 WHz-1) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies (BCGs) follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  2. Physical properties of AGN host galaxies as a probe of supermassive black hole feeding mechanisms

    NASA Astrophysics Data System (ADS)

    Gatti, M.; Lamastra, A.; Menci, N.; Bongiorno, A.; Fiore, F.

    2015-04-01

    Using an advanced semi-analytical model (SAM) for galaxy formation, we investigated the statistical effects of assuming two different mechanisms for triggering AGN activity on the properties of AGN host galaxies. We considered a first accretion mode where AGN activity is triggered by disk instabilities (DI) in isolated galaxies, and a second feeding mode where galaxy mergers and fly-by events (interactions, IT) are responsible for producing a sudden destabilization of large quantities of gas, causing the mass inflow onto the central supermassive black hole. The effects of including IT and DI modes in our SAM were studied and compared with observations separately to single out the regimes in which they might be responsible for triggering AGN activity. We obtained the following results: i) the predictions of our model concerning the stellar mass functions of AGN hosts point out that both DI and IT modes are able to account for the observed abundance of AGN host galaxies with M∗ ≲ 1011M⊙; for more massive hosts, the DI scenario predicts a much lower space density than the IT model in every redshift bin, lying below the observational estimates for redshift z > 0.8. ii) The analysis of the colour-magnitude diagram of AGN hosts for redshift z < 1.5 can provide a good observational test to effectively distinguish between DI and IT mode, since DIs are expected to yield AGN host galaxy colours skewed towards bluer colours, while in the IT scenario the majority of hosts are expected to reside in the red sequence. iii) While both IT and DI scenarios can account for AGN triggered in main sequence or starburst galaxies, DIs fail in triggering AGN activity in passive galaxies. The lack of DI AGN in passive hosts is rather insensitive to changes in the model describing the DI mass inflow, and it is mainly caused by the criterion for the onset of disk instabilities included in our SAM. iv) The two modes are characterized by a different duration of the AGN phase, with DIs

  3. On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM-Newton

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo; Bianchi, Stefano

    2007-02-01

    We present results of a high-resolution soft X-ray (0.2-2 keV) spectroscopic study of a sample of 69 nearby obscured active galactic nuclei (AGNs) observed with the reflection grating spectrometer (RGS) onboard XMM-Newton. This is the largest sample ever studied with this technique so far. The main conclusions of our study can be summarized as follows: (i) narrow radiative recombination continua are detected in about 36 per cent of the objects in our sample (in 26 per cent their intrinsic width is <=10 eV); (ii) higher order transitions are generally enhanced with respect to pure photoionization, indicating that resonant scattering plays an important role in the ionization/excitation balance. These results support the scenario, whereby the active nucleus is responsible for the X-ray `soft excess' almost ubiquitously observed in nearby obscured AGNs via photoionization of circumnuclear gas. They confirm on a statistical basis the conclusions drawn from the detailed study of the brightest spectra in the sample. Furthermore, we propose a criterion to statistically discriminate between AGN-photoionized sources and starburst galaxies, based on intensity of the forbidden component of the OVII Heα triplet (once normalized to the OVIII Lyα) coupled with the integrated luminosity in He- and H-like oxygen lines.

  4. Search for gamma-ray-emitting active galactic nuclei in the Fermi-LAT unassociated sample using machine learning

    SciTech Connect

    Doert, M.; Errando, M. E-mail: errando@astro.columbia.edu

    2014-02-10

    The second Fermi-LAT source catalog (2FGL) is the deepest all-sky survey available in the gamma-ray band. It contains 1873 sources, of which 576 remain unassociated. Machine-learning algorithms can be trained on the gamma-ray properties of known active galactic nuclei (AGNs) to find objects with AGN-like properties in the unassociated sample. This analysis finds 231 high-confidence AGN candidates, with increased robustness provided by intersecting two complementary algorithms. A method to estimate the performance of the classification algorithm is also presented, that takes into account the differences between associated and unassociated gamma-ray sources. Follow-up observations targeting AGN candidates, or studies of multiwavelength archival data, will reduce the number of unassociated gamma-ray sources and contribute to a more complete characterization of the population of gamma-ray emitting AGNs.

  5. Rest-frame UV Single-epoch Black Hole Mass Estimates of Low-luminosity AGNs at Intermediate Redshifts

    NASA Astrophysics Data System (ADS)

    Karouzos, Marios; Woo, Jong-Hak; Matsuoka, Kenta; Kochanek, Christopher S.; Onken, Christopher A.; Kollmeier, Juna A.; Park, Dawoo; Nagao, Tohru; Kim, Sang Chul

    2015-12-01

    The ability to accurately derive black hole (BH) masses at progressively higher redshifts and over a wide range of continuum luminosities has become indispensable in the era of large-area extragalactic spectroscopic surveys. In this paper, we present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts and luminosities comparable to the local Hβ reverberation-mapped active galactic nuclei (AGNs). We focus on the Mg ii, C iv, and C iii] broad emission lines and compare them to both Hα and Hβ. We use newly acquired near-infrared spectra from the Fiber-fed Multi-object Spectrograph instrument on the Subaru telescope for 89 broad-lined AGNs at redshifts between 0.3 and 3.5, complemented by data from the AGES survey. We employ two different prescriptions for measuring the emission line widths and compare the results. We confirm that Mg ii shows a tight correlation with Hα and Hβ, with a scatter of ∼0.25 dex. The C iv and C iii] estimators, while showing larger scatter, are viable virial mass estimators after accounting for a trend with the UV-to-optical luminosity ratio. We find an intrinsic scatter of ∼0.37 dex between Balmer and carbon virial estimators by combining our data set with previous high redshift measurements. This updated comparison spans a total of three decades in BH mass. We calculate a virial factor for C iv/C iii] {log}{f}{{C}{{IV}}/{{C}}{{III}}]}=0.87 with an estimated systematic uncertainty of ∼0.4 dex and find excellent agreement between the local reverberation mapped AGN sample and our high-z sample.

  6. Revisiting Stochastic Variability of AGNs with Structure Functions

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-08-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to the expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs), have triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ˜9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the “subensemble” SFs in the redshift-absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power law (SPL; in the “red noise regime” after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at γ =0.55+/- 0.08 (0.52 ± 0.06) and is consistent with the DRW model. There is a hint of a weak correlation of γ with the luminosity and a lack of correlation with the black hole mass. The typical decorrelation timescale in the optical is τ =0.97+/- 0.46 year. The SF amplitude at one year obtained from the SPL fitting is {{SF}}0=0.22+/- 0.06 mag and is overestimated because the SF is already at the turnover part, so the true value is {{SF}}0=0.20+/- 0.06 mag. The asymptotic variability is {{SF}}∞ =0.25+/- 0.06 mag. It is strongly anticorrelated with both the luminosity and the Eddington ratio and is correlated with the black hole mass. The reliability of these results is fortified with Monte Carlo simulations.

  7. Liners and Low Luminosity AGN in the ROSAT Database

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; West, Donald K. (Technical Monitor)

    2003-01-01

    This program has led to a series of papers being written and published in the Astrophysical Journal. Together these papers try to explain major parts of the LINER and low luminosity AGN puzzle. One paper ('Accretion Disk Instabilities, Cold Dark Matter Models, and Their Role in Quasar Evolution', Hatziminaoglou E., Siemiginowska A., & Elvis M., 2001, ApJ, 547, 90) describes an analytical model for the evolution of the quasar luminosity function. By combining the Press-Schechter formalism for the masses of initial structures with the luminosity distribution for a population of single mass black holes given by an unstable accretion disk an almost complete end-to-end physics-based model of quasar evolution is produced. In this model black holes spend 75% of their time in a low accretion state (at L(Edd)). This low state population of black holes is likely to be observed as the LINER and low luminosity AGNs in the local universe. Another paper ('Broad Emission Line Regions in AGN: the Link with the Accretion Power', Nicastro F., 2000, ApJ Letters, 530, L65) gives a physical basis for why low state black holes appear as LINERS. By linking the Lightman-Eardley instability in an accretion disk to the ori.gin of a wind that contains the broad emission line cloud material this model explains the large widths seen in these lines as being the Keplerian velocity of the disk at the instability radius. For LINERS the key is that below an accretion rate of 10(exp -3)M(sub Edd)the Lightman-Eardley instability falls within the innermost stable orbit of the disk, and so leaves the entire disk stable. No wind occurs, and so no broad emission lines are seen. Most LINERS are likely to be black holes in this low state. Tests of this model are being considered.

  8. AGN-stimulated cooling of hot gas in elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Valentini, Milena; Brighenti, Fabrizio

    2015-04-01

    We study the impact of relatively weak active galactic nucleus (AGN) feedback on the interstellar medium (ISM) of intermediate and massive elliptical galaxies. We find that the AGN activity, while globally heating the ISM, naturally stimulates some degree of hot gas cooling on scales of several kpc. This process generates the persistent presence of a cold ISM phase, with mass ranging between 104 and ≳ 5 × 107 M⊙, where the latter value is appropriate for group centred, massive galaxies. Widespread cooling occurs where the ratio of cooling to free-fall time before the activation of the AGN feedback satisfies tcool/tff ≲ 70, that is we find a less restrictive threshold than commonly quoted in the literature. This process helps explaining the body of observations of cold gas (both ionized and neutral/molecular) in Ellipticals and, perhaps, the residual star formation detected in many early-type galaxies. The amount and distribution of the off-centre cold gas vary irregularly with time. The cold ISM velocity field is irregular, initially sharing the (outflowing) turbulent hot gas motion. Typical velocity dispersions of the cold gas lie in the range 100-200 km s-1. Freshly generated cold gas often forms a cold outflow and can appear kinematically misaligned with respect to the stars. We also follow the dust evolution in the hot and cold gas. We find that the internally generated cold ISM has a very low dust content, with representative values of the dust-to-gas ratio of 10-4-10-5. Therefore, this cold gas can escape detection in the traditional dust-absorption maps.

  9. Revisiting Stochastic Variability of AGNs with Structure Functions

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-08-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to the expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs), have triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ˜9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the “subensemble” SFs in the redshift–absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power law (SPL; in the “red noise regime” after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at γ =0.55+/- 0.08 (0.52 ± 0.06) and is consistent with the DRW model. There is a hint of a weak correlation of γ with the luminosity and a lack of correlation with the black hole mass. The typical decorrelation timescale in the optical is τ =0.97+/- 0.46 year. The SF amplitude at one year obtained from the SPL fitting is {{SF}}0=0.22+/- 0.06 mag and is overestimated because the SF is already at the turnover part, so the true value is {{SF}}0=0.20+/- 0.06 mag. The asymptotic variability is {{SF}}∞ =0.25+/- 0.06 mag. It is strongly anticorrelated with both the luminosity and the Eddington ratio and is correlated with the black hole mass. The reliability of these results is fortified with Monte Carlo simulations.

  10. Submillimetre observations of WISE-selected high-redshift, luminous AGN and their surrounding overdense environments

    NASA Astrophysics Data System (ADS)

    Jones, Suzy F.

    2016-08-01

    We present JCMT SCUBA-2 850 μm submillimetre (submm) observations of 10 mid-infrared (mid-IR) luminous active galactic nuclei (AGNs), detected by the Wide-field Infrared Survey Explorer (WISE) all-sky IR survey and 30 that have also been detected by the NVSS/FIRST radio survey. These rare sources are selected by their extremely red mid-IR spectral energy distributions (SEDs). Further investigations show that they are highly obscured, have abundant warm AGN-heated dust and are thought to be experiencing intense AGN feedback. When comparing the number of submm galaxies detected serendipitously in the surrounding 1.5 arcmin to those in blank-field submm surveys, there is a very significant overdensity, of order 3-5, but no sign of radial clustering centred at our primary objects. The WISE-selected AGN thus reside in 10-Mpc-scale overdense environments that could be forming in pre-viralized clusters of galaxies. WISE-selected AGNs appear to be the strongest signposts of high-density regions of active, luminous and dusty galaxies. SCUBA-2 850 μm observations indicate that their submm fluxes are low compared to many popular AGN SED templates, hence the WISE/radio-selected AGNs have either less cold and/or more warm dust emission than normally assumed for typical AGN. Most of the targets have total IR luminosities ≥1013 L⊙, with known redshifts of 20 targets between z ˜ 0.44-4.6.

  11. On the relation between X-ray absorption and optical extinction in AGN

    NASA Astrophysics Data System (ADS)

    Ordovás-Pascual, Ignacio; Mateos, Silvia; Carrera, Francisco J.; Wiersema, Klaas; Caccianiga, Alessandro; Severgnini, Paola; Della Ceca, Roberto; Ballo, Lucia; Moretti, Alberto

    2016-08-01

    According to the Unified Model of Active Galactic Nuclei (AGN), an X-ray unabsorbed AGN should appear as unobscured in the optical (Type-1) and viceversa (Type-2). However, there is an important fraction (10-30%) of AGN whose optical and X-ray classifications do not match. To provide insight into the origin of such apparent discrepancies, we have conducted two analyses: 1) a detailed study of the UV-to-near-IR emission of two X-ray unabsorbed Type-2 AGN drawn from the Bright Ultra-Hard XMM-Newton Survey (BUXS); 2) a statistical analysis of the optical obscuration and X-ray absorption properties of 159 Type-1 AGN drawn from BUXS to determine the distribution of dust-to-gas ratios in AGN over a broad range of luminosities and redshifts. In our works we have also determined the impact of contamination from the AGN hosts in the optical classification of AGNs. Our studies are already provided very exciting results such as the detection of objects with extreme dust-to-gas ratios, between 300-10000 times below the Galactic dust-to-gas ratio.

  12. Agnes Mary Clerke and the Rise of Astrophysics

    NASA Astrophysics Data System (ADS)

    Brück, M. T.

    2002-05-01

    Acknowledgements; Introduction; 1. Family background in County Cork; 2. Ireland and Italy; 3. London, the literary scene; 4. The History of Astronomy; 5. A circle of astronomers; 6. A visit to South Africa; 7. The System of the Stars; 8. Social life in scientific circles; 9. Homer, the Herschels and a revised History; 10. The opinion moulder; 11. Popularisation, cryogenics and evolution; 12. Problems in Astrophysics; 13. Women in astronomy in Britain in Agnes Clerke's time; 14. Revised System of the Stars; 15. Cosmogonies, cosmology and Nature's spiritual clues; 16. Last days and retrospect; 17. Epilogue; Notes; Appendix; Bibliography; Index.

  13. Agnes Mary Clerke and the Rise of Astrophysics

    NASA Astrophysics Data System (ADS)

    Brück, M. T.

    2008-03-01

    Acknowledgements; Introduction; 1. Family background in County Cork; 2. Ireland and Italy; 3. London, the literary scene; 4. The History of Astronomy; 5. A circle of astronomers; 6. A visit to South Africa; 7. The System of the Stars; 8. Social life in scientific circles; 9. Homer, the Herschels and a revised History; 10. The opinion moulder; 11. Popularisation, cryogenics and evolution; 12. Problems in Astrophysics; 13. Women in astronomy in Britain in Agnes Clerke's time; 14. Revised System of the Stars; 15. Cosmogonies, cosmology and Nature's spiritual clues; 16. Last days and retrospect; 17. Epilogue; Notes; Appendix; Bibliography; Index.

  14. The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN

    NASA Astrophysics Data System (ADS)

    Pozzi, F.; Vignali, C.; Comastri, A.; Bellocchi, E.; Fritz, J.; Gruppioni, C.; Mignoli, M.; Maiolino, R.; Pozzetti, L.; Brusa, M.; Fiore, F.; Zamorani, G.

    2010-07-01

    Aims: We combine near-to-mid-IR Spitzer data with shorter wavelength observations (optical to X-rays) to get insight into the properties of a sample of luminous, obscured active galactic nuclei (AGN). We aim at modelling their broad-band spectral energy distributions (SEDs) in order to estimate the main parameters related to the dusty torus that is assumed to be responsible for the reprocessed IR emission. Our final goal is to estimate the intrinsic nuclear luminosities and the Eddington ratios for our luminous, obscured AGN. Methods: The sample comprises 16 obscured high-redshift (0.9 ⪉ z ⪉ 2.1), X-ray luminous quasars (L2-10 keV ~ 1044 erg s-1) selected from the HELLAS2XMM survey in the 2-10 keV band. The optical-IR SEDs are described by a multi-component model that includes a stellar component to account for the optical and near-IR emission, an AGN component that dominates in the mid-IR (mainly emission from a dusty torus heated by nuclear radiation), and a starburst to reproduce the far-IR bump. A radiative transfer code to compute the spectrum and intensity of dust reprocessed emission was extensively tested against our multiwavelength data. While the torus parameters and the BH accretion luminosities are a direct output of the SED-fitting procedure, the BH masses were estimated indirectly by means of the local Mbulge-MBH relation. Results: The majority (~80%) of the sources show moderate optical depth (τ9.7 µm ≤ 3), and the derived column densities NH are consistent with the X-ray inferred values (1022 ⪉ NH ⪉ 3 × 1023 cm-2) for most of the objects, confirming that the sources are moderately obscured Compton-thin AGN. Accretion luminosities in the range 5 × 1044 ⪉ Lbol ⪉ 4 × 1046 erg s-1 are inferred from the multiwavelength fitting procedure. We compare model luminosities with those obtained by integrating the observed SED, finding that the latter are lower by a factor of ~2 in the median. The discrepancy can be as high as an order of

  15. AGN proximity zone fossils and the delayed recombination of metal lines

    NASA Astrophysics Data System (ADS)

    Oppenheimer, Benjamin D.; Schaye, Joop

    2013-09-01

    We model the time-dependent evolution of metal-enriched intergalactic and circumgalactic gas exposed to the fluctuating radiation field from an active galactic nucleus (AGN). We consider diffuse gas densities (nH = 10-5-10-2.5 cm-3) exposed to the extra-galactic background (EGB) and initially in thermal equilibrium (T ˜ 104-104.5 K). Once the proximate AGN field turns on, additional photo-ionization rapidly ionizes the HI and metals. The enhanced AGN radiation field turns off after a typical AGN lifetime (τAGN = 1-20 Myr) and the field returns to the EGB intensity, but the metals remain out of ionization equilibrium for time scales that can significantly exceed τAGN. We define this phase as the AGN proximity zone `fossil' phase and show that high ionization stages (e.g. OVI, NeVIII, MgX) are in general enhanced, while the abundances of low ions (e.g. CIV, OIV, MgII) are reduced. In contrast, HI re-equilibrates rapidly (≪τAGN) owing to its low neutral fraction at diffuse densities. We demonstrate that metal column densities of intervening gas observed in absorption in quasar sight lines are significantly affected by delayed recombination for a wide range of densities, metallicities, AGN strengths, AGN lifetimes and AGN duty cycles. As an example, we show that a fossil zone model can simultaneously reproduce the observed NeVIII, MgII, HI and other metal columns of the z = 0.927 PG1206+259 absorption system observed by Tripp et al. using a single, T ˜ 104 K phase model. At low redshift even moderate-strength AGN that are off for 90 per cent of the time could significantly enhance the high-ion metal columns in the circum-galactic media of galaxies observed without active AGN. Fossil proximity zones may be particularly important during the quasar era, z ˜ 2-5. Indeed, we demonstrate that at these redshifts a large fraction of the metal-enriched intergalactic medium may consist of out-of-equilibrium fossil zones. AGN proximity zone fossils allow a whole new class

  16. THE CONNECTIONS BETWEEN THE UV AND OPTICAL Fe ii EMISSION LINES IN TYPE 1 AGNs

    SciTech Connect

    Kovacević-Dojcinović, Jelena; Popović, Luka Č. E-mail: lpopovic@aob.bg.ac.rs

    2015-12-15

    We investigate the spectral properties of the UV (λλ2650–3050 Å) and optical (λλ4000–5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe ii{sub opt}) versus EW [O iii] 5007 Å and EW Fe ii{sub opt} versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  17. X-ray evidence for ultra-fast outflows in AGNs

    NASA Astrophysics Data System (ADS)

    Tombesi, Francesco; Sambruna, Rita; Braito, Valentina; Reeves, James; Reynolds, Christopher; Cappi, Massimo

    2012-07-01

    X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 radio galaxies observed with XMM-Newton and Suzaku. We assessed the global detection significance of the absorption lines and performed a detailed photo-ionization modeling. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1} and the associated mechanical power is high, in the range ˜10^{43}--10^{45} erg/s. Therefore, UFOs are capable to provide a significant contribution to the AGN cosmological feedback and their study can provide important clues on the connection between accretion disks, winds and jets.

  18. The Connections Between the UV and Optical Fe ii Emission Lines in Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Kovačević-Dojčinović, Jelena; Popović, Luka Č.

    2015-12-01

    We investigate the spectral properties of the UV (λλ2650-3050 Å) and optical (λλ4000-5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe iiopt) versus EW [O iii] 5007 Å and EW Fe iiopt versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  19. Knowledge Discovery workflows for the classification of AGNs in multiwavelength spaces: the Blazars case

    NASA Astrophysics Data System (ADS)

    D'Abrusco, Raffaele; Massaro, F.; Paggi, A.; Fabbiano, G.

    2014-07-01

    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.

  20. Knowledge Discovery workflows for the classification of AGNs in multi-wavelength spaces: the Blazars case

    NASA Astrophysics Data System (ADS)

    D'Abrusco, Raffaele; Massaro, F.; Paggi, A.; Fabbiano, G.

    2014-07-01

    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.

  1. Stellar and quasar feedback in concert: effects on AGN accretion, obscuration, and outflows

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Torrey, Paul; Faucher-Giguère, Claude-André; Quataert, Eliot; Murray, Norman

    2016-05-01

    We study the interaction of feedback from active galactic nuclei (AGN) and a multiphase interstellar medium (ISM), in simulations including explicit stellar feedback, multiphase cooling, accretion-disc winds, and Compton heating. We examine radii ˜0.1-100 pc around a black hole (BH), where the accretion rate on to the BH is determined and where AGN-powered winds and radiation couple to the ISM. We conclude: (1) the BH accretion rate is determined by exchange of angular momentum between gas and stars in gravitational instabilities. This produces accretion rates ˜0.03-1 M⊙ yr-1, sufficient to power luminous AGN. (2) The gas disc in the galactic nucleus undergoes an initial burst of star formation followed by several million years where stellar feedback suppresses the star formation rate (SFR). (3) AGN winds injected at small radii with momentum fluxes ˜LAGN/c couple efficiently to the ISM and have dramatic effects on ISM properties within ˜100 pc. AGN winds suppress the nuclear SFR by factors ˜10-30 and BH accretion rate by factors ˜3-30. They increase the outflow rate from the nucleus by factors ˜10, consistent with observational evidence for galaxy-scale AGN-driven outflows. (4) With AGN feedback, the predicted column density distribution to the BH is consistent with observations. Absent AGN feedback, the BH is isotropically obscured and there are not enough optically thin sightlines to explain type-I AGN. A `torus-like' geometry arises self-consistently as AGN feedback evacuates gas in polar regions.

  2. Upholding the unified model for AGN: VLT/FORS2 spectropolarimetry of Seyfert 2 galaxies

    NASA Astrophysics Data System (ADS)

    Ramos Almeida, Cristina; Martínez González, M.; Asensio Ramos, A.; Acosta Pulido, J.; Hönig, S.; Alonso-Herrero, A.; Tadhunter, C.; González-Martín, O.

    2016-08-01

    The origin of the unification model for AGN was the detection of broad hydrogen recombination lines in the optical polarized spectrum of the Seyfert 2 galaxy (Sy2) NGC 1068. Since then, a search for the hidden broad-line region (HBLR) of nearby Sy2s started, but polarized broad lines have only been detected in ~30-40% of the nearby Sy2s observed to date. Here we present new VLT/FORS2 optical spectropolarimetry of a sample of 15 Sy2s, including Compton-thin and Compton-thick sources. The sample includes six galaxies without previously published spectropolarimetry, some of them normally treated as non-hidden BLR (NHBLR) objects in the literature, and four Sy2s classified as NHBLR based on previous data. We report >4sigma detections of a HBLR in 11 of these galaxies (73% of the sample). Our results confirm that at least some NHBLRs were misclassified, bringing previous publications reporting differences between HBLR and NHBLR objects into question. We detect broad Ha and Hb components in polarized light for 9 targets, and just broad Ha for the other two. We do not find any correlation between the properties of the polarized spectra and the column densities measured from the X-rays or torus inclination, but a larger sample is required to confirm this.

  3. THE LICK AGN MONITORING PROJECT: BROAD-LINE REGION RADII AND BLACK HOLE MASSES FROM REVERBERATION MAPPING OF Hbeta

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Baliber, Nairn; Bennert, Vardha Nicola; Greene, Jenny E.; Hidas, Marton G.; Canalizo, Gabriela; Hiner, Kyle D.; Filippenko, Alexei V.; Ganeshalingam, Mohan; Lee, Nicholas; Li, Weidong; Serduke, Frank J. D.; Silverman, Jeffrey M.; Steele, Thea N.; Gates, Elinor L.; Malkan, Matthew A.; Minezaki, Takeo; Sakata, Yu

    2009-11-01

    We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range approx10{sup 6}-10{sup 7} M {sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hbeta emission. We present here the light curves for all the objects in this sample and the subsequent Hbeta time lags for the nine objects where these measurements were possible. The Hbeta lag time is directly related to the size of the broad-line region (BLR) in AGNs, and by combining the Hbeta lag time with the measured width of the Hbeta emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local M {sub BH}-sigma{sub *}relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hbeta line profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting BLR clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on the physical models of the BLR by the velocity-resolved response

  4. Simulations of the OzDES AGN reverberation mapping project

    SciTech Connect

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; Banerji, Manda; McMahon, Richard; Sharp, Rob; Lidman, C.

    2015-08-26

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ~500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ~35–45 % of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ~1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for Hβ, MgIIλ2798, and C IVλ1549. As a result, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.

  5. The AGN-driven shock in NGC 4472

    NASA Astrophysics Data System (ADS)

    Gendron-Marsolais, Marie-Lou; Kraft, Ralph P.; Bogdan, Akos; Forman, William R.; Hlavacek-Larrondo, Julie; Jones, Christine; Nulsen, Paul; Randall, Scott W.; Roediger, Elke

    2016-04-01

    Chandra observations of most cool core clusters of galaxies have revealed large cavities where the inflation of the jet-driven radio bubbles displace the cluster gas. In a few cases, outburst shocks, likely driven by cavity inflation, are detected in the ambient gas. AGN-driven shocks may be key to balancing the radiative losses as shocks will increase the entropy of, and thereby heat, the diffuse gas. We will present initial results on deep Chandra observations of the nearby (D=17 Mpc) early-type massive elliptical galaxy NGC 4472, the most optically luminous galaxy in the local Universe, lying on the outskirts of the Virgo cluster. The X-ray observations show clear cavities in the X-ray emission at the position of the radio lobes, and rings of enhanced X-ray emission just beyond the lobes. We will present results from our analysis to determine whether the lobes are inflating supersonically or are rising buoyantly. We will compare the energy and power of this AGN outburst with previous powerful radio outbursts in clusters and groups to determine whether this outburst lies on the same scaling relations or whether it represents a new category of outburst.

  6. 'Harder when Brighter' Spectral Variability in Low-Luminosity AGN

    NASA Astrophysics Data System (ADS)

    Connolly, S.; McHardy, I.; Skipper, C.; Dwelly, T.

    2015-07-01

    We present X-ray spectral variability of four low accretion rate AGN - M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the `softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely main source of spectral variability is found to be luminosity-dependent changes in the photon index of the power law component. An anticorrelation between the photon index and the count rate is found in all of the sources. The anticorrelation is likely to be caused by accretion via a radiatively-inefficient accretion flow, expected in low-Eddington ratio systems such as these, and/or due to the presence of a jet. This behaviour is similar to that seen in the `hard state' of X-ray binaries, implying that these LLAGN are in a similar state.

  7. AGN feedback on the ISM of 3C 236

    NASA Astrophysics Data System (ADS)

    Labiano, A.; García-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Tremblay, G.; Neri, R.; Fuente, A.; Morganti, R.; Oosterloo, T.

    2013-03-01

    We have carried out 1mm/3mm continuum and 12CO(2-1) line high resolution observations to identify the footprints of AGN feedback on 3C 236. The CO emission comes from a spatially resolved disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of our data, we do not detect any outflow signatures in the cold molecular gas. Re-inspection of optical and IR spectra, shows the presence of a previously unknown ionized gas outflow. The star-formation efficiency in 3C 236, is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt law. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the factor of 10-50 lower SFE that has been claimed to characterize evolved powerful radio galaxies. The recent reactivation of the AGN in 3C 236 is a likely explanation for the early evolutionary status of its molecular disk.

  8. Hot Gas and AGN Feedback in Galaxies and Nearby Groups

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Forman, William; Bogdan, Akos; Randall, Scott; Kraft, Ralph; Churazov, Eugene

    2013-07-01

    Massive galaxies harbor a supermassive black hole at their centers. At high redshifts, these galaxies experienced a very active quasar phase, when, as their black holes grew by accretion, they produced enormous amounts of energy. At the present epoch, these black holes still undergo occasional outbursts, although the mode of their energy release is primarily mechanical rather than radiative. The energy from these outbursts can reheat the cooling gas in the galaxy cores and maintain the red and dead nature of the early-type galaxies. These outbursts also can have dramatic effects on the galaxy-scale hot coronae found in the more massive galaxies. We describe research in three areas related to the hot gas around galaxies and their supermassive black holes. First we present examples of galaxies with AGN outbursts that have been studied in detail. Second, we show that X-ray emitting low-luminosity AGN are present in 80% of the galaxies studied. Third, we discuss the first examples of extensive hot gas and dark matter halos in optically faint galaxies.

  9. An AGN Identification for 3EG J2006-2321

    NASA Technical Reports Server (NTRS)

    Wallace, P. M.; Halpern, J. P.; Magalhaes, A. M.; Thompson, D. J.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321 (l = 18 deg.82, b = -26 deg.26). The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of archived radio data indicate that its most probable identification is with PMN J2005-2310, a flat-spectrum radio quasar with a 5GHz flux density of 260 mJy. Study of the V = 19.3 optical counterpart indicates a redshift of 0.833 and variable linear polarization. No X-ray source has been detected near the position of PMN J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper limit provides for a spectral energy distribution with global characteristics similar to those of known gamma-ray blazars. Taken together, these data indicate that 3EG J2006-2321, listed as unidentified in the 3rd EGRET Catalog, is a member of the blazar class of AGN. The 5-GHz radio flux density of this blazar is the lowest of the 68 EGRET-detected AGN. The fact that EGRET has detected such a source has implications for unidentified EGRET sources, particularly those at high latitudes (absolute value of b greater than 30 deg), many of which may be blazars.

  10. Dynamics of matter available for accretion in AGN

    NASA Astrophysics Data System (ADS)

    Proga, Daniel

    We propose to study fluid dynamics in the central regions of active galaxies. Several key attributes of AGN, such as infall rates onto the central black hole and the geometry and rates of outward energy and momentum transfer, are determined in their central regions. However, despite many years of intensive studies, how radiation and mass outflows affect the structure of active galaxies remains uncertain, mostly because multi- dimensional geometrical effects and the dynamics of gas and dust are poorly understood. We will construct time-dependent, multi-dimensional radiation hydrodynamical simulations to study, from first principles, the morphology of central galactic flows on scales ranging from subparsec to tens of parsecs. The novel features of our proposed models are: (1) radiative heating and cooling of dust and gas, (2) radiation pressure on dust and gas,
(3) the essential physics of dust sublimation, and (4) radiative transfer. The results of this project will reveal the basic physical properties of flows in AGN with unprecedented accuracy and detail. We will use our models to calculate diagnostics such as line profiles, broad band spectra, and intensity maps. These diagnostics will be compared with observations by both current NASA missions such as HST, Chandra, Spitzer, and Swift and planned missions such as JWST.

  11. XMM-Newton, powerful AGN winds and galaxy feedback

    NASA Astrophysics Data System (ADS)

    Pounds, K.; King, A.

    2016-06-01

    The discovery that ultra-fast ionized winds - sufficiently powerful to disrupt growth of the host galaxy - are a common feature of luminous AGN is major scientific breakthrough led by XMM-Newton. An extended observation in 2014 of the prototype UFO, PG1211+143, has revealed an unusually complex outflow, with distinct and persisting velocities detected in both hard and soft X-ray spectra. While the general properties of UFOs are consistent with being launched - at the local escape velocity - from the inner disc where the accretion rate is modestly super-Eddington (King and Pounds, Ann Rev Astron Astro- phys 2015), these more complex flows have raised questions about the outflow geometry and the importance of shocks and enhanced cooling. XMM-Newton seems likely to remain the best Observatory to study UFOs prior to Athena, and further extended observations, of PG1211+143 and other bright AGN, have the exciting potential to establish the typical wind dynamics, while providing new insights on the accretion geometry and continuum source structure. An emphasis on such large, coordinated observing programmes with XMM-Newton over the next decade will continue the successful philosophy pioneered by EXOSAT, while helping to inform the optimum planning for Athena

  12. Dielectric recombination and stability of warm gas in AGN

    SciTech Connect

    Chakravorty, Susmita; Kembhavi, Ajit K.; Elvis, Martin; Ferland, Gary; Badnell, N. R.

    2012-05-25

    High resolution ultraviolet and X-ray spectra show that material outflow occur from the close neighbourhoods of super-massive black holes in active galactic nuclei (AGN). The absorption features seen in the high resolution soft X-ray spectra is attributed to gas which is conventionally termed as the warm absorber (WA) and often the thermal equilibrium (stability) curve is used as a theoretical tool to offer insights into the nature of the WA. The shape of the stability curve is determined by factors like the spectral energy distribution of the ionizing flux and the chemical composition of the absorbing gas. We found that the stability curves obtained under the same set of assumptions for the prevalent physical conditions in the AGN environment, but using recently derived dielectronic recombination rates, give significantly different results from what is predicted with older atomic data. The variations in phase space region of the stability curves corresponding to WAs, lead to different physical predictions. The results obtained with the current dielectronic recombination rate coefficients are more reliable because the WA models along the stability curve have computed, updated coefficient values.

  13. The faint radio AGN population in the spotlight

    NASA Astrophysics Data System (ADS)

    Herrera Ruiz, Noelia; Middelberg, Enno

    2016-08-01

    To determine the AGN component in the faint radio population is fundamental in galaxy evolution studies. A relatively easy and direct way to determine which galaxies do have a radio-active AGN is a detection using the Very Long Baseline Interferometry (VLBI) technique. The goal of this project is to study with statistically relevant numbers the faint radio source population using VLBI observations. To achieve this goal, the project is divided into two parts. In the first part, we have observed ~3000 radio sources in the COSMOS extragalactic field with the Very Long Baseline Array (VLBA) at 1.4GHz. We have detected 468 sources. In the second part, we have observed ~200 radio sources in the COSMOS field with extremely high sensitivity using the VLBA together with the Green Bank Telescope (GBT) at 1.4GHz, to explore an even fainter population in the flux density regime of tens of uJy. We are currently calibrating this data. In this overview I will present the survey design, observations, and calibration, along with some first results.

  14. A Model for Type 2 Coronal Line Forest (CLiF) AGNs

    NASA Astrophysics Data System (ADS)

    Glidden, Ana; Rose, Marvin; Elvis, Martin; McDowell, Jonathan

    2016-06-01

    We present a model for the classification of Coronal Line Forest Active Galactic Nuclei (CLiF AGNs). CLiF AGNs are of special interest due to their remarkably large number of emission lines, especially forbidden high-ionization lines (FHILs). Rose et al. suggest that their emission is dominated by reflection from the inner wall of the obscuring region rather than direct emission from the accretion disk. This makes CLiF AGNs laboratories to test AGN-torus models. Modeling an AGN as an accreting supermassive black hole surrounded by a cylinder of dust and gas, we show a relationship between the viewing angle and the revealed area of the inner wall. From the revealed area, we can determine the amount of FHIL emission at various angles. We calculate the strength of [Fe vii]λ6087 emission for a number of intermediate angles (30°, 40°, and 50°) and compare the results with the luminosity of the observed emission line from six known CLiF AGNs. We find that there is good agreement between our model and the observational results. The model also enables us to determine the relationship between the type 2:type 1 AGN fraction vs the ratio of torus height to radius, h/r.

  15. Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

    NASA Technical Reports Server (NTRS)

    Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

    2004-01-01

    One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

  16. The cosmic evolution of massive black holes in the Horizon-AGN simulation

    NASA Astrophysics Data System (ADS)

    Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

    2016-08-01

    We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted on to BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z ˜ 2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive haloes present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z = 3 and z = 2, respectively.

  17. Dissecting galaxies: spatial and spectral separation of emission excited by star formation and AGN activity

    NASA Astrophysics Data System (ADS)

    Davies, Rebecca L.; Groves, Brent; Kewley, Lisa J.; Dopita, Michael A.; Hampton, Elise J.; Shastri, Prajval; Scharwächter, Julia; Sutherland, Ralph; Kharb, Preeti; Bhatt, Harish; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stéphanie; Srivastava, Shweta

    2016-10-01

    The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and active galactic nucleus (AGN) activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra. In this paper, we describe how integral field data can be used to spectrally and spatially separate emission associated with star formation from emission associated with accretion on to an AGN. We demonstrate our method using integral field data for two AGN host galaxies (NGC 5728 and NGC 7679) from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). The spectra of NGC 5728 and NGC 7679 form clear sequences of AGN fraction on standard emission line ratio diagnostic diagrams. We show that the emission line luminosities of the majority (>85 per cent) of spectra along each AGN fraction sequence can be reproduced by linear superpositions of the emission line luminosities of one AGN dominated spectrum and one star formation dominated spectrum. We separate the Hα, Hβ, [N II]λ6583, [S II]λλ6716, 6731, [O III]λ5007 and [O II]λλ3726, 3729 luminosities of every spaxel into contributions from star formation and AGN activity. The decomposed emission line images are used to derive the star formation rates and AGN bolometric luminosities for NGC 5728 and NGC 7679. Our calculated values are mostly consistent with independent estimates from data at other wavelengths. The recovered star-forming and AGN components also have distinct spatial distributions which trace structures seen in high-resolution imaging of the galaxies, providing independent confirmation that our decomposition has been successful.

  18. The radio luminosity function and redshift evolution of radio-mode and quasar-mode AGN

    NASA Astrophysics Data System (ADS)

    Pracy, Mike

    2016-08-01

    The properties of the AGN population indicate that there are two fundamentally different accretion modes operating. In the quasar-mode, material is accreted onto the supermassive black hole via a small, thin, optically luminous accretion disc. Accretion in this mode is recognisable by emission lines in the optical spectrum. However, there is a population of AGN observable only by their radio emission and without optical emission lines. These radio-mode AGN are likely powered by radiatively inefficient accretion from a hot gas halo. I will describe the cosmic evolution of these two populations via radio luminosity functions. The radio luminosity functions are constructed from a new survey of over 4000 radio galaxies out to z=1, all with confirmed redshifts and their accretion mode classified from their optical spectra. This is 20 times larger than the only other survey used to make such a measurement. The radio-mode AGN population displays no statistically significant evolution in space density out to redshift z=1. In contrast the quasar mode AGN exhibits rapid evolution in space density, increasing by a factor of 8 over the same redshift range. The characteristic break in the radio luminosity function occurs at a significantly higher power for the quasar-mode AGN in comparison to the radio-mode AGN and we demonstrate this is consistent with the two populations representing fundamentally different accretion modes. The radio luminosity function is used to estimate the total amount of mechanical energy available for radio mode feedback as a function of redshift, and is found to be in good agreement with cosmological models and previous measurements. Again, by separating by accretion mode, the previously estimated increase in available mechanical energy per unit volume out to z=1 (approximately a factor of 2) can be attributed to the rapid evolution of the quasar-mode AGN, while for the classical radio-mode AGN the total mechanical energy output remains roughly

  19. TORUS2015: The AGN unification scheme after 30 years

    NASA Astrophysics Data System (ADS)

    Gandhi, P.; Hoenig, S. F.

    2015-09-01

    The torus paradigm has proved to be remarkably successful at unifying the observed zoo of active galaxy (AGN) classes, despite having many manifest holes. The field is still data-driven with novel observational results at multiple wavelengths emerging rapidly. We are only now beginning to map out the structure of dusty gas feeding and obscuring AGN, and to model its evolution in galaxy growth. But these have also brought out several apparently contradictory results which must hold the key to future progress. As we celebrate 30 years of the paradigm, this is the perfect time to draw together our current knowledge and reassess the state of the field. This will be an international workshop at the University of Southampton, UK, with the objective of laying out the major challenges to the field and paving future research directions. Our hope is to facilitate plenty of informal discussions between multiwavelength observers and theorists, addressing some key issues: * What is the main driver in the unification scheme? What are the roles of orientation, mass accretion rate and feedback? * What is the nature and structure of gas and dust in the torus? Do we have a self-consistent picture across multiple wavelengths? * How critical is the role of the torus as an interface between small nuclear scales and large galactic scales? Does galaxy evolution necessarily require tori? * How close are we to self-consistently simulating nuclear activity including AGN feeding and nuclear star-formation? Workshop Rationale The three themes of accretion, orientation, and evolution will be covered through invited and solicited contributions. Different to other conferences, we are building each session around some key papers that have shaped the field or those with great future potential to do so. We specifically pit competing ideas against each other to help painting a realistic picture of the state-of-the-art. Each session will end with discussion rounds delving into important future

  20. Mid-infrared interferometry of 23 AGN tori: On the significance of polar-elongated emission

    NASA Astrophysics Data System (ADS)

    López-Gonzaga, N.; Burtscher, L.; Tristram, K. R. W.; Meisenheimer, K.; Schartmann, M.

    2016-06-01

    Context. Detailed high-resolution studies of active galactic nuclei (AGN) with mid-infrared (MIR) interferometry have revealed parsec-sized dust emission that is elongated in the polar direction in four sources. Aims: Using a larger, coherently analyzed sample of AGN observed with MIR interferometry, we aim to identify elongated MIR emission in a statistical sample of sources. More specifically, we wish to determine if there is indeed a preferred direction of the elongation and whether this direction is consistent with a torus-like structure or with a polar emission. Methods: We investigated the significance of the detection of an elongated shape in the MIR emission by fitting elongated Gaussian models to the interferometric data at 12 μm. We paid special attention to (1) the uncertainties caused by an inhomogeneous (u,v) coverage; (2) the typical errors in the measurements; and (3) the spatial resolution achieved for each object. Results: From our sample of 23 sources, we are able to find elongated parsec-scale, MIR emission in five sources: three type 2s, one type 1i, and one type 1. Elongated emission in four of these sources has been published before; NGC 5506 is a new detection. The observed axis ratios are typically around 2 and the position angle of the 12 μm emission for all the elongated sources always seems to be closer to the polar axis of the system than to the equatorial axis. Two other objects, NGC 4507 and MCG-5-23-16, with reasonably well-mapped (u,v) coverage and good signal-to-noise ratios, appear to have a less elongated 12 μm emission. Conclusions: Our finding that sources showing elongated MIR emission are preferentially extended in polar direction sets strong constraints on torus models or implies that both the torus and NLR/outflow region have to be modeled together. In addition, models used for SED fitting will have to be revised to include emission from polar dust.

  1. Is There an Obscured AGN in the Normal Galaxy IRASF01063-8034

    NASA Technical Reports Server (NTRS)

    Greenhill, Lincoln J.

    2005-01-01

    The XMM target for this program is ostensibly a "normal" galaxy, but the presence of water maser emission indicated that it may be an obscured AGN. Our primary goal is to test this hypothesis; detection hard X-ray emission and a reflection-dominated spectrum would indicate an AGN is present. Demonstration that the local universe contains obscured AGN is important to constraining models of the hard cosmic X-ray background, as is identification of efficient methods to locate them (e.g., ground-based detection of maser emission at microwave frequencies).

  2. The host galaxies and narrow-line regions of four double-peaked [OIII] AGNs

    SciTech Connect

    Villforth, Carolin; Hamann, Fred

    2015-03-01

    Major gas-rich mergers of galaxies are expected to play an important role in triggering and fueling luminous active galactic nuclei (AGNs). The mechanism of AGN fueling during mergers, however, remains poorly understood. We present deep multi-band (u/r/z) imaging and long-slit spectroscopy of four double-peaked [OIII] emitting AGNs. This class of object is likely associated with either kiloparsec-separated binary AGNs or final stage major mergers, although AGNs with complex narrow-line regions (NLRs) are known contaminants. Such objects are of interest since they represent the onset of AGN activity during the merger process. Three of the four double-peaked [OIII] emitters studied have been confirmed as major mergers using near-infrared imaging and one is a confirmed X-ray binary AGN. All AGNs are luminous, radio-quiet to radio-intermediate, and have redshifts of 0.1AGN suggests that the merger of a binary black hole can take longer than 1 Gyr. All AGNs hosted by merging galaxies have companions at distances ⩽150 kpc. The NLRs have large sizes (10 kpc < r < 100 kpc) and consist of compact clumps with considerable relative velocities between components (∼200–650 km s{sup −1}). We detect broad, predominantly blue, wings with velocities up to ∼1500 km s{sup −1} in [OIII], indicative of powerful outflows. The outflows are compact (<5 kpc) and co-spatial with nuclear regions showing considerable reddening, consistent with enhanced star formation. One source shows an offset between gas and stellar kinematics, consistent with either a bipolar flow or a counter-rotating gas disk. In all other sources, the ionized gas

  3. VizieR Online Data Catalog: RM AGNs accretion rates and BH masses (Du+, 2016)

    NASA Astrophysics Data System (ADS)

    Du, P.; Wang, J.-M.; Hu, C.; Ho, L. C.; Li, Y.-R.; Bai, J.-M.

    2016-05-01

    We select all AGNs with reverberation mapping (RM) data (here only broad Hβ line), which yield robust BH mass estimates needed for our analysis. All RM AGNs before 2013 are summarized by Bentz et al. (2013ApJ...767..149B). Our project to search for super-Eddington accreting massive black holes (SEAMBHs) has monitored about 25 candidates and successfully measured Hβ lags ({tau}Hβ) in 14 AGNs to date (Du et al. 2015, J/ApJ/806/22) and other five objects monitored between 2014 and 2015 (to be submitted). See section 2 for further explanations. (2 data files).

  4. Fossil shell emission in dying radio loud AGNs

    NASA Astrophysics Data System (ADS)

    Kino, M.; Ito, H.; Kawakatu, N.; Orienti, M.; Nagai, H.; Wajima, K.; Itoh, R.

    2016-02-01

    We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolution of shells after stopping the jet energy injection. We find that the shell emission overwhelms that of the radio lobes soon after stopping the jet energy injection because fresh electrons are continuously supplied into the shell via the forward shock, while the radio lobes rapidly fade out without jet energy injection. We find that such fossil shells can be a new class of target sources for SKA telescope. Next, we apply the model to the nearby radio source 3C84. Then, we find that the fossil shell emission in 3C84 is less luminous in the radio band while it is bright in the TeV γ-ray band and can be detectable by CTA. Data from STELLA

  5. Jets and Outflows in Radio Galaxies: Implications for AGN Feedback

    NASA Astrophysics Data System (ADS)

    Torresi, Eleonora; Grandi, Paola; Costantini, Elisa; Palumbo, Giorgio G. C.

    One of the main debated astrophysical problems is the role of the AGN feedback in galaxy formation. It is known that massive black holes have a profound effect on the formation and evolution of galaxies, but how black holes and galaxies communicate is still an unsolved problem. For Radio Galaxies, feedback studies have mainly focused on jet/cavity systems in the most massive and X-ray luminous galaxy clusters. The recent high-resolution detection of warm absorbers in some Broad Line Radio Galaxies allow us to investigate the interplay between the nuclear engine and the surrounding medium from a different perspective. We report on the detection of warm absorbers in two Broad Line Radio Galaxies, 3C 382 and 3C 390.3, and discuss the physical and energetic properties of the absorbing gas. Finally, we attempt a comparison between radio-loud and radio-quiet outflows.

  6. Synergy Between Observations of AGN with GLAST and MAXI

    SciTech Connect

    Madejski, Grzegorz

    2002-03-25

    In five years' time we will witness the launch of two important missions developed to observe celestial sources in the high energy regime: GLAST, sensitive in the high energy {gamma}-ray band, and MAXI, the all-sky X-ray monitor. Simultaneous monitoring observations by the two instruments will be particularly valuable for variable sources, allowing cross-correlations of time series between the two bands. We present the anticipated results from such observations of active galaxies, and in particular, of the jet-dominated sub-class of AGN known as blazars. We discuss the constraints on the structure and emission processes--and in particular, on the internal shock models currently invoked to explain the particle acceleration processes in blazars--that can be derived with simultaneous {gamma}-ray and X-ray data.

  7. A Mixture Evolution Scenario of the AGN Radio Luminosity Function

    NASA Astrophysics Data System (ADS)

    Yuan, Zunli; Wang, Jiancheng; Zhou, Ming; Mao, Jirong

    2016-03-01

    We propose a mixture evolution scenario to model the evolution of the radio luminosity function (RLF) of steep-spectrum AGNs (active galactic nuclei), based on a Bayesian method. In this scenario, the shape of the RLF is determined by both the density and luminosity evolution. Our models indicate that the density evolution is positive until a redshift of ∼ 0.9, at which point it becomes negative, while the luminosity evolution is positive to a higher redshift (z∼ 5 for model B and z∼ 3.5 for model C), where it becomes negative. Our mixture evolution model works well, and the modeled RLFs are in good agreement with previous determinations. The mixture evolution scenario can naturally explain the luminosity-dependent evolution of the RLFs.

  8. Relativistic Effects on Reflection X-ray Spectra of AGN

    SciTech Connect

    Lee, Khee-Gan; Fuerst, Steven V.; Brandwardi-Raymond, Graziella; Wu, Kinwah; Crowley, Oliver; /University Coll. London

    2007-01-05

    We have calculated the reflection component of the X-ray spectra of active galactic nuclei (AGN) and shown that they can be significantly modified by the relativistic motion of the accretion flow and various gravitational effects of the central black hole. The absorption edges in the reflection spectra suffer severe energy shifts and smearing. The degree of distortion depends on the system parameters, and the dependence is stronger for some parameters such as the inner radius of the accretion disk and the disk viewing inclination angles. The relativistic effects are significant and are observable. Improper treatment of the reflection component of the X-ray continuum in spectral fittings will give rise to spurious line-like features, which will mimic the fluorescent emission lines and mask the relativistic signatures of the lines.

  9. AGN Spectral Energy Distributions of GLAST Telescope Network Program Objects

    NASA Astrophysics Data System (ADS)

    Adkins, Jeff; Lacy, Mark; Daou, Doris; Rapp, Steve; Stefaniak, Linda

    2005-03-01

    The Gamma-Ray Large Area Space Telescope (GLAST) has a proposed observing list that includes AGNs and Polars bright enough to be observed optically by amateurs and students. This observing list is maintained by the "GLAST Telescope Network" (GTN) and includes a number of objects that have yet to be observed by the Spitzer Space Telescope. Our project will observe one of these objects with the Spitzer MIPS and the IRAC instruments to determine their Spectral Energy Distribution (SED), which will be compared to a computer model of disk emission in order to determine what component of the SED is due to the disk and what component is due to synchrotron radiation induced by the jets. In addition we will observe our program objects prior to, simultaneously with, and after Spitzer observes them. This gives a direct connection from Spitzer research to student activities in the classroom.

  10. Radio Studies of Galactic Objects, Galaxies and AGNs

    NASA Astrophysics Data System (ADS)

    Han, J. L.; Sun, X. H.; Yang, J.; Wielebinski, R.

    2003-02-01

    The Sino-German Radio Astronomy Conference was held in Xi'an between July 18th and 25th 2002. This conference was also a meeting of radio astronomy in China. The partner group of Max-Plack-Institut for Radioastronomie at National Astronomical Observatories of China took the responsibility for detailed organizations. The conference was focused on "Radio studies of Galactic objects, galaxies and AGNs", with 80 partici- pants plus the 6 helpers. Most radio astronomers in China together with about 30 students enjoyed the fruitful discussions with 9 German senior scientists and 6 famous experts from other countries. In addition, the his- torical sites and culture environments specifically in Xi'an also attracted a dozen companions of delegates.

  11. CMB quenching of high-redshift radio-loud AGNs

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Haardt, F.; Ciardi, B.; Sbarrato, T.; Gallo, E.; Tavecchio, F.; Celotti, A.

    2015-10-01

    The very existence of more than a dozen of high-redshift (z ≳ 4) blazars indicates that a much larger population of misaligned powerful jetted active galactic nucleus (AGN) was already in place when the Universe was ≲1.5 Gyr old. Such parent population proved to be very elusive, and escaped direct detection in radio surveys so far. High-redshift blazars themselves seem to be failing in producing extended radio lobes, raising questions about the connection between such class and the vaster population of radio galaxies. We show that the interaction of the jet electrons with the intense cosmic microwave background (CMB) radiation explains the lack of extended radio emission in high-redshift blazars and in their parent population, helping to explain the apparently missing misaligned counterparts of high-redshift blazars. On the other hand, the emission from the more compact and more magnetized hotspots are less affected by the enhanced CMB energy density. By modelling the spectral energy distribution of blazar lobes and hotspots, we find that most of them should be detectable by low-frequency deep radio observations, e.g. by LOw-Frequency ARray for radio astronomy and by relatively deep X-ray observations with good angular resolution, e.g. by the Chandra satellite. At high redshifts, the emission of a misaligned relativistic jet, being debeamed, is missed by current large sky area surveys. The isotropic flux produced in the hotspots can be below ˜1 mJy and the isotropic lobe radio emission is quenched by the CMB cooling. Consequently, even sources with very powerful jets can go undetected in current radio surveys, and misclassified as radio-quiet AGNs.

  12. Simulations of the OzDES AGN reverberation mapping project

    DOE PAGES

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; et al

    2015-08-26

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ~500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrainmore » the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ~35–45 % of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ~1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for Hβ, MgIIλ2798, and C IVλ1549. As a result, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.« less

  13. Do the Kepler AGN light curves need reprocessing?

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.; Williams, Joshua; Carini, Michael T.

    2015-10-01

    We gauge the impact of spacecraft-induced effects on the inferred variability properties of the light curve of the Seyfert 1 AGN Zw 229-15 observed by Kepler. We compare the light curve of Zw 229-15 obtained from the Kepler MAST data base with a reprocessed light curve constructed from raw pixel data. We use the first-order structure function, SF(δt), to fit both light curves to the damped power-law PSD (power spectral density) of Kasliwal et al. On short time-scales, we find a steeper log PSD slope (γ = 2.90 to within 10 per cent) for the reprocessed light curve as compared to the light curve found on MAST (γ = 2.65 to within 10 per cent) - both inconsistent with a damped random walk (DRW) which requires γ = 2. The log PSD slope inferred for the reprocessed light curve is consistent with previous results that study the same reprocessed light curve. The turnover time-scale is almost identical for both light curves (27.1 and 27.5 d for the reprocessed and MAST data base light curves). Based on the obvious visual difference between the two versions of the light curve and on the PSD model fits, we conclude that there remain significant levels of spacecraft-induced effects in the standard pipeline reduction of the Kepler data. Reprocessing the light curves will change the model inferenced from the data but is unlikely to change the overall scientific conclusions reached by Kasliwal et al. - not all AGN light curves are consistent with the DRW.

  14. VizieR Online Data Catalog: Spitzer MIR AGN survey. I. (Lacy+, 2013)

    NASA Astrophysics Data System (ADS)

    Lacy, M.; Ridgway, S. E.; Gates, E. L.; Nielsen, D. M.; Petric, A. O.; Sajina, A.; Urrutia, T.; Cox Drews, S.; Harrison, C.; Seymour, N.; Storrie-Lombardi, L. J.

    2013-10-01

    A wide range of optical facilities and instruments were used for spectroscopic follow-up of our AGN candidates. Most of the bright samples were followed up with 3-5m telescopes and longslit spectroscopy (Hale with COSMIC, SOAR with Goodman, and Shane with Kast), whereas the fainter samples were followed up with multifiber and/or 6-8m class telescopes (Blanco with Hydra, MMT with Hectospec, and Gemini-South with GMOS (program GS-2008B-C4)). We also obtained spectra of some of the bright candidates with a successful poor weather (scheduling band 4) program at Gemini-South (program GS-2008B-Q86). Some objects had spectra available in archives from the SDSS, 2dF, (Colless et al. 2001, Cat. VII/250) or 6dF (Jones et al. 2009, Cat. VII/259) surveys and some have redshifts and classifications in the literature, all found using the NASA Extragalactic Database (NED). Table 2 gives details of the spectroscopic observations or literature references as appropriate. For some high-redshift candidates with ambiguous or low signal-to-noise optical spectra, we were able to obtain near-infrared spectra with the IRTF using SpeX (2007 June), Gemini with NIRI (program GN2009B-C-8), and Triplespec (2008 July and 2011 July) on Palomar. (5 data files).

  15. Investigating properties of a set of variable AGN with cluster analysis

    NASA Astrophysics Data System (ADS)

    Nair, A. D.

    1997-05-01

    Optical and gamma-ray properties of a sample of active galactic nuclei monitored at the Rosemary Hill Observatory are analysed using cluster analysis. Cluster analysis can be used to analyse large amounts of data with many variables and investigate linear or non-linear relationships in the data. It is found that the time-scale of variation is not related to the amplitude of variability. For BLLacs and optically violent variable (OVV) quasars the variability is proportional to the redshift and absolute magnitude, but this is not true for quasars in this sample. The analysis shows that gamma-ray-loud AGN tend to be associated with superluminal sources with OVV-like characteristics. The gamma-ray fluxes, for both OVV quasars and BLLacs, are proportional to the apparent transverse velocity, and this may point to beaming as the dominant cause for the gamma-ray flux. A large majority of the OVV quasars that display a large amplitude of variability are gamma- ray-loud, but this is not true for BL Lacs.

  16. DIAGNOSTICS OF AGN-DRIVEN MOLECULAR OUTFLOWS IN ULIRGs FROM HERSCHEL-PACS OBSERVATIONS OF OH AT 119 μm

    SciTech Connect

    Spoon, H. W. W.; Lebouteiller, V.; Farrah, D.; González-Alfonso, E.; Bernard-Salas, J.; Urrutia, T.; Rigopoulou, D.; Verma, A.; Westmoquette, M. S.; Smith, H. A.; Afonso, J.; Pearson, C.; Cormier, D.; Efstathiou, A.; Borys, C.; Etxaluze, M.; Clements, D. L.

    2013-10-01

    We report on our observations of the 79 and 119 μm doublet transitions of OH for 24 local (z < 0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH 119 μm profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, while other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This result locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to ∼2000 km s{sup –1}, with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km s{sup –1} (1000 km s{sup –1}). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km s{sup –1} are thought to require an active galactic nucleus (AGN) to drive them, about two-thirds of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity. No such correlation is found with the IR-derived star formation rate. The highest outflow velocities are found among sources that are still deeply embedded. We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less-obscured AGNs. Four of our sources show high-velocity wings in their [C II] fine-structure line profiles, implying neutral gas outflow masses of at least (2-4.5) × 10{sup 8} M{sub ☉}.

  17. Suzaku View of the Swift/BAT Active Galactic Nuclei (I): Spectral Analysis of Six AGNs and Evidence for Two Types of Obscured Population

    NASA Technical Reports Server (NTRS)

    Eguchi, Satoshi; Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard F.; Tueller, Jack

    2009-01-01

    We present a systematic spectral analysis with Suzaku of six AGNs detected in the Swift/BAT hard X-ray (15-200 keV) survey, Swift J0138.6-4001, J0255.2-0011, J0350.1-5019, J0505.7-2348, J0601.9-8636, and J1628.1-5145. This is considered to be a representative sample of new AGNs without X-ray spectral information before the BAT survey. We find that the 0.5-200 keV spectra of these sources can be uniformly fit with a base model consisting of heavily absorbed (log NH >23.5/sq cm) transmitted components, scattered lights, a reflection component, and an iron-K emission line. There are two distinct groups, three "new type" AGNs (including the two sources reported by Ueda et al. 2007) with an extremely small scattered fraction (f(sub scat) < 0:5%) and strong reflection component (R = omega/2pi > or equal to 0.8 where omega is the solid angle of the reflector), and three "classical type" ones with f(sub scat > 0.5% and R < or approx. 0.8. The spectral parameters suggest that the new type has an optically thick torus for Thomson scattering (N(sub H) approx. 10(exp 25)/sq cm) with a small opening angle theta approx. 20deg viewed in a rather face-on geometry, while the classical type has a thin torus (N(sub H) approx. 10(exp 23-24)/sq cm) with theta > or approx. 30deg. We infer that a significant number of new type AGNs with an edge-on view is missing in the current all-sky hard X-ray surveys. Subject headings: galaxies: active . gamma rays: observations . X-rays: galaxies . X-rays: general

  18. Extragalactic jets as probes of distant clusters of galaxies and the clusters occupied by bent radio AGN (COBRA) survey

    NASA Astrophysics Data System (ADS)

    Blanton, Elizabeth L.; Paterno-Mahler, Rachel; Wing, Joshua D.; Ashby, M. L. N.; Golden-Marx, Emmet; Brodwin, Mark; Douglass, E. M.; Randall, Scott W.; Clarke, T. E.

    2015-03-01

    We are conducting a large survey of distant clusters of galaxies using radio sources with bent jets and lobes as tracers. These radio sources are driven by AGN and achieve their bent morphologies through interaction with the surrounding gas found in clusters of galaxies. Based on low-redshift studies, these types of sources can be used to identify clusters very efficiently. We present initial results from our survey of 653 bent-double radio sources with optical hosts too faint to appear in the SDSS. The sample was observed in the infrared with Spitzer, and it has revealed ~200 distant clusters or proto-clusters in the redshift range z ~ 0.7 - 3.0. The sample of bent-doubles contains both quasars and radio galaxies enabling us to study both radiative and kinetic mode feedback in cluster and group environments at a wide range of redshifts.

  19. The Chandra Survey of Outflows in AGN with Resolved Spectroscopy (SOARS)

    NASA Astrophysics Data System (ADS)

    Marshall, Herman; Evans, Daniel

    2012-07-01

    We present results from the Chandra SOARS (Survey Outflows in AGN with Resolved Spectroscopy) program, using spatially resolved Chandra High Energy Transmission Grating spectroscopy of the kpc-scale narrow line regions around some of our nearest AGN, including the Circinus Galaxy, NGC 1068, Mrk 3, and NGC 3393. We use the neutral and photoexcited lines measurable using the HETG Spectrometer to (1) measure the mass and energy imparted by the AGN outflow into its kpc-scale environment; and (2) create a full kinematic map of the galaxy, thereby directly constraining the extent of the outflow. Our results have key implications for the role of galactic-scale outflows in AGN as moderators of galaxy evolution

  20. AGN 190383, a novel phospholipase inhibitor with topical anti-inflammatory activity.

    PubMed

    De Vries, G W; Lee, G; Amdahl, L; Wenzel, M; Garst, M; Wheeler, L A

    1991-09-01

    AGN 190383 is a 5-hydroxy-2(5H)-furanone ring analog of the marine natural product manoalide. When applied topically, AGN 190383 inhibits phorbol ester induced mouse ear edema. It is a potent inhibitor of bee venom phospholipase A2 and blocks the release of arachidonic acid from calcium ionophore A23187 stimulated human neutrophils. AGN 190383 also inhibits both hormone-operated and depolarization-dependent calcium mobilization in GH3 cells, as well as fMLP stimulated increases in free cytosolic calcium in human PMNs. Furthermore, it is also able to block the release of the neutral protease elastase from stimulated neutrophils. The effects of AGN 190383 on arachidonic acid metabolism and leukocyte function may account, in part, for its anti-inflammatory activity in vivo.

  1. Characterizing the redshifts and luminosities of WISE selected obscured AGN using SALT optical spectra.

    NASA Astrophysics Data System (ADS)

    Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Mike A.; Jones, Mackenzie L.

    2016-08-01

    We present the results of several optical spectroscopic surveys covering over 100 candidate luminous obscured active galactic nuclei (AGN) identified by their mid-infrared emission detected with the Wide-Field Infrared Survey Explorer (WISE). These galaxies were selected based on red WISE colors and galaxy-like optical emission, and were studied using long-slit optical spectroscopy with the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT). Our spectra were analyzed to obtain redshifts and emission line flux ratios for each galaxy. These results verify that WISE is an effective section method for luminous obscured AGN, allow for the characterization of redshifts and luminosities of the WISE color selected obscured AGN population, and could potentially contribute to large statistical studies of obscured AGN distributions in the future.

  2. The Contribution of Compton-Thick AGN/ULIRGs to the X-Ray Background

    NASA Astrophysics Data System (ADS)

    Nardini, Emanuele

    Accretion onto the supermassive black holes located at the centre of Active Galactic Nuclei(AGN) is one of the most efficient power sources in the Universe, and provides a significant contribution to the energy radiated over cosmic times. The spectral shape of the X-ray background and its progressive resolution strongly suggests that most AGN are heavily obscured by large amounts of dust and gas. Their primary radiation field is reprocessed and re-emitted at longer wavelengths, driving a huge IR luminosity. Ultraluminous Infrared Galaxies (ULIRGs) are the local counterparts of the high-redshift (z < 1 3) IR systems that harbour the bulk of obscured nuclear activity in the early Universe. We have been recently awarded Suzaku observations of two ULIRGs, IRAS 00182 7112 and IRAS 12127 1412, for a total exposure time of 150 ks. Both the sources are known to host an elusive AGN whose intrinsic luminosity is estimated to fall in the quasar range. Although classified as Low-Ionization Nuclear Emission-line Regions in the optical, these ULIRGs sport the typical features of buried AGN in the mid-IR. IRAS 12127 1412 was observed for the first time in the X-rays by our group. Its Chandra spectrum clearly shows the signatures of AGN reflection at 2 10 keV. Similar properties were previously found in IRAS 00182 7112. Our Suzaku observations will allow to pinpont the AGN emission above 10 keV, and will provide fundamental information on the physical and geometrical structure of Compton-thick AGN embedded in a nuclear starburst. These sources are believed to experience the very initial phase of the AGN feedback on the surrounding environm