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Sample records for agn sample lbas

  1. The ROSAT/NVSS AGN sample

    NASA Astrophysics Data System (ADS)

    Paronyan, Gurgen M.; Abrahamyan, Hayk V.; Harutyunyan, Gohar S.; Mickaelian, Areg M.

    2014-07-01

    We attempt to create an X-ray/radio AGN catalog and make its multiwavelength studies. ROSAT Bright Source Catalogue (BSC) contains 18,806 and ROSAT Faint Source Catalogue (FSC), 105,922 X-ray sources giving the total number of ROSAT X-ray sources 124,727 (one source is listed twice). On the other hand, NVSS radio catalogue contains 1,773,484 sources. Taking into account that X-ray sources contain AGN, bright stars and galaxies, clusters, white dwarfs (WD), cataclysmic variables (CV), etc., the cross-identification with radio catalogue may distinguish the extragalactic sources. We have cross-correlated ROSAT catalogs with NVSS one with a search radius 30 arcsec. 9,193 associations have been found. To distinguish AGN from the normal bright galaxies and clusters, Veron-Cetty & Veron AGN catalog (v.13, 2010; VCV-13) containing 168,940 objects have been used. A cross-correlation of the 9,193 ROSAT/NVSS sources with the VCV-13 with a search radius 30 arcsec resulted in 3,094 associations. Thus we are left with more 6,099 X-ray/radio sources without an optical identification. Brighter objects are normal bright galaxies, while we believe that all faint ones are candidate AGN with some contamination of distant clusters. SDSS spectroscopic survey allows us classify objects by activity types, and a number of our candidate AGN is found to be present in SDSS. We attempt to find connections between the fluxes in different wavelength ranges, which will allow us to confirm AGN and blazars candidates and in some cases find new ones.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. The VIMOS VLT Deep Survey: the faint type-1 AGN sample

    NASA Astrophysics Data System (ADS)

    Gavignaud, I.; Bongiorno, A.; Paltani, S.; Mathez, G.; Zamorani, G.; Møller, P.; Picat, J. P.; Le Brun, V.; Marano, B.; 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.; 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.; Lamareille, F.; Mellier, Y.; Merluzzi, P.; Ripepi, V.; Rizzo, D.; Vergani, D.

    2006-10-01

    We present the type-1 active galactic nuclei (AGN) sample extracted from the VIMOS VLT Deep Survey's first observations of 21 000 spectra in 1.75 deg^2. This sample, which is purely magnitude-limited and free of morphological or color-selection biases, contains 130 broad-line AGN (BLAGN) spectra with redshift up to 5. Our data are divided into a wide (I_AB ≤ 22.5) and a deep (I_AB ≤ 24) subsample containing 56 and 74 objects, respectively. Because of its depth and selection criteria, this sample is uniquely suited for studying the population of faint type-1 AGN. Our measured surface density (~472 ± 48 BLAGN per square degree with I_AB ≤ 24) is significantly higher than that of any other optically selected sample of BLAGN with spectroscopic confirmation. By applying a morphological and color analysis to our AGN sample, we find that (1) ~23 % of the AGN brighter than I_AB=22.5 are classified as extended, and this percentage increases to ~42% for those with z < 1.6; (2) a non-negligible fraction of our BLAGN are lying close to the color-space area occupied by stars in the u^*-g' versus g'-r' color-color diagram. This leads us to the conclusion that the classical optical-ultraviolet preselection technique, if employed at such deep magnitudes (I_AB=22.5) in conjuction with a preselection of point-like sources, can miss up to ~35% of the AGN population. Finally, we present a composite spectrum of our sample of objects. While the continuum shape is very similar to that of the SDSS composite at short wavelengths, it is much redder than that of the SDSS composite at λ ≥ 3000 Å. We interpret this as due to significant contamination from emission of the host galaxies, as expected from the faint absolute magnitudes sampled by our survey.

  8. 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.

  9. Is the dependence of spectral index on luminosity real in optically selected AGN samples?

    NASA Astrophysics Data System (ADS)

    Tang, Su Min; Zhang, Shuang Nan; Hopkins, Philip F.

    2007-05-01

    We critically examine the dependence of spectral index on luminosity in optically selected AGN samples. An analysis of optically selected high-z quasars showed an anticorrelation of αOX, the spectral index between the rest-frame 2500 Å and 2 keV, with optical luminosity. We examine this relationship by means of Monte Carlo simulations and conclude that a constant αOX independent of optical luminosity is still consistent with this high-z sample. We further find that contributions of large dispersions and narrow range of optical luminosity are most important for the apparent, yet artificial, αOX-lo correlation reported. We also examine another, but more complete, low-z optical selected AGN sub-sample from Steffen et al., and our analysis shows that a constant αOX independent of optical luminosity is also consistent with the data. By comparing X-ray and optical luminosity functions, we find that a luminosity-independent αOX is in fact more preferred than the luminosity-dependent αOX model. We also discuss the selection effects caused by flux limits, which might systematically bias the lX-lo relation and cause discrepancy in optically selected and X-ray selected AGN samples. To correctly establish a dependence of αOX of AGNs on their luminosity, a larger and more complete sample is needed and consequences of luminosity dispersions and selection effects in flux-limited samples must be taken into account properly.

  10. The VVDS type-1 AGN sample: the faint end of the luminosity function

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Zamorani, G.; Gavignaud, I.; Marano, B.; Paltani, S.; Mathez, G.; Møller, P.; Picat, J. P.; Cirasuolo, M.; Lamareille, F.; Bottini, D.; Garilli, B.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Scaramella, R.; Scodeggio, M.; Tresse, L.; Vettolani, G.; Zanichelli, A.; Adami, C.; 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.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Zucca, E.; Hatziminaoglou, E.; Polletta, M.; Bondi, M.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Gregorini, L.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

    2007-09-01

    In a previous paper (Gavignaud et al. 2006, A&A, 457, 79), we presented the type-1 Active Galactic Nuclei (AGN) sample obtained from the first epoch data of the VIMOS-VLT Deep Survey (VVDS). The sample consists of 130 faint, broad-line AGN with redshift up to z=5 and 17.5sample is thus free of the morphological and color selection biases, that lead to significant incompleteness in the optical surveys of faint AGN. In this paper we present the measurement of the Optical Luminosity Function up to z=3.6 derived from this sample, we compare our results with previous results from brighter samples both at low and at high redshift and finally, through the estimate of the bolometric luminosity function, we compare them also with the results from X-ray and mid-IR selected samples. Our data, more than one magnitude fainter than previous optical surveys, allow us to constrain the faint part of the luminosity function up to high redshift. A comparison of our data with the 2dF sample at low redshift (1 < z < 2.1) shows that the VVDS data can not be well fitted with the PLE models derived by previous samples. Qualitatively, this appears to be due to the fact that our data suggest the presence of an excess of faint objects at low redshift (1.0sample with the large sample of bright AGN extracted from the SDSS DR3 (Richards et al. 2006b, AJ, 131, 2766) and testing a number of different evolutionary models, we find that the model which better represents the combined luminosity functions, over a wide range of redshift and luminosity, is a luminosity dependent density evolution (LDDE) model, similar to those derived from the major X-surveys. Such a parameterization allows the redshift of the AGN space density peak to change as a function of luminosity and explains the excess of faint AGN that we find at 1.0 < z < 1.5. On the basis of this model we find, for the

  11. The CoNFIG FRI sample: evolution of FRI galaxies and their role in AGN feedback.

    NASA Astrophysics Data System (ADS)

    Gendre, Melanie; Ricci, Roberto; Wall, Jasper; Feain, Ilana; Best, Philip; Dunlop, James; Grant, Julie; Taylor, Russ; Stil, Jeroen

    2008-10-01

    The proposal is to examine two major AGN aspects: (1) detailed testing and analysis of the FRI-galaxy space density evolution, (2) to study the polarization properties of AGN cores as a function of flux and redshift and (3) a precise history of cosmic downsizing ('differential evolution') in radio AGN to examine the importance of FRI versus FRII sources in the AGN feedback process now appearing to govern galaxy formation. The investigation is based on the CoNFIG FRI sub-samples (obtained from the 1.4-GHz NVSS in regions of FIRST) and the CENSORS sample (obtained from the NVSS and the deep EIS optical survey in a small region of southern sky). From these we have a total of 206 extragalactic sources for which we desire unambiguous morphologies and FRI/FRII classification in particular. Of the 206 sources, we request ATCA 6km array observations at 3 cm for 40 sources which, from our previous observations and analysis, remain ambiguous in classification. This sample can at last define the detailed cosmic evolution of FRI radio sources together with the 'transition region' to FRII sources.

  12. AGN Astrophysics via Multi-Frequency Monitoring of γ-ray Blazars in the Fermi-GST Era

    NASA Astrophysics Data System (ADS)

    Angelakis, E.; Angelakis, E.; Fuhrmann, L.; Zensus, J. A.; Nestoras, I.; Marchili, N.; Krichbaum, T. P.; Ungerechts, H.; Max-Moerbeck, W.; Pavlidou, V.; Pearson, T. J.; Readhead, A. C. S.; Richards, J. L.; Stevenson, M. A.

    2010-10-01

    The F-GAMMA-project is the coordinated effort of several observatories to understand the AGN phenomenon and specifically blazars via multi-frequency monitoring in collaboration with the Fermi-GST satellite since January 2007. The core observatories are: the Effelsberg 100-m, the IRAM 30-m and the OVRO 40-m telescope covering the range between 2.6 and 270 GHz. Effelsberg and IRAM stations do a monthly monitoring of the cm to sub-mm radio spectra of 60 selected blazars whereas the OVRO telescope is observing roughly 1200 objects at 15 GHz with a dense sampling of 2 points per week. The calibration uncertainty even at high frequencies, is of a few percent. 47% of the Effelsberg/Pico Veleta sample is included in the LBAS list. An update of the monitored sample is currently underway.

  13. 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.

  14. 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

  15. X-ray spectral properties of the AGN sample in the northern XMM-XXL field

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Merloni, Andrea; Georgakakis, Antonis; Menzel, Marie-Luise; Buchner, Johannes; Nandra, Kirpal; Salvato, Mara; Shen, Yue; Brusa, Marcella; Streblyanska, Alina

    2016-06-01

    In this paper we describe and publicly release a catalogue consisting of 8445 point-like X-ray sources detected in the XMM-XXL north survey. For the 2512 AGN which have reliable spectroscopy from SDSS-III/BOSS, we present the X-ray spectral fitting which has been computed with a Bayesian approach. We have also applied an X-ray spectral stacking method to different sub-samples, selected on the basis of the AGN physical properties (L2-10 keV, z, MBH, λEdd and NH). We confirm the well-known Iwasawa-Taniguchi effect in our luminosity-redshift sub-samples, and argue that such an effect is due to a decrease in the covering factor of a distant obscuring `torus' with increasing X-ray luminosity. By comparing the distribution of the reflection fraction, the ratio of the normalization of the reflected component to the direct radiation, we find that the low-luminosity, low-redshift sub-sample had systematically higher reflection fraction values than the high-redshift, high-luminosity one. On the other hand, no significant difference is found between samples having similar luminosity but different redshift, suggesting that the structure of the torus does not evolve strongly with redshift. Contrary to previous works, we do not find evidence for an increasing photon index at high Eddington ratio. This may be an indication that the structure of the accretion disc changes as the Eddington ratio approaches unity. Comparing our X-ray spectral analysis results with the optical spectral classification, we find that ˜20 per cent of optical type-1 AGN show an X-ray absorbing column density higher than 1021.5 cm- 2, and about 50 per cent of type-2 AGN have an X-ray absorbing column density less than 1021.5 cm- 2. We suggest that the excess X-ray absorption shown in the high-luminosity optical type-1 AGN can be due to small-scale dust-free gas within (or close to) the broad-line region, while in the low-luminosity ones it can be due to a clumpy torus with a large covering factor.

  16. 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.

  17. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. I. Emission-Line Diagnostics

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    We 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 μm, [Ne II] 12.81μm , [Ne III] 15.56 μm and [Ne V] μm, and hard X-ray show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGN are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The correlations between all the mid-infrared emission lines and BAT luminosities are statistically significant. The mid-infrared emission line fluxes are highly correlated, with the worst correlations for [Ne V]-[Ne II] and [O IV]-[Ne II], as a result of enhanced [Ne II] in some sources due to nuclear stellar activity, however the tightness of these mid-infrared correlations 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 [Ne III] an [O IV] lines do not unambiguously identify AGNs as stand-along diagnostics, however the BAT AGNs fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. While it is likely that detection of [Ne V] indicates the presence of an AGN, the [Ne V] line is weak compared to [O IV] and may not be detected in weak AGN. We suggest that a composite method using [Ne II], [Ne III], and [O IV] provides a more robust diagnostic.

  18. 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.

  19. 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.

  20. 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.

  1. The AGN content of ultraluminous IR galaxies: High resolution VLA imaging of the IRAS 1 Jy ULIRG sample

    NASA Astrophysics Data System (ADS)

    Nagar, N. M.; Wilson, A. S.; Falcke, H.; Veilleux, S.; Maiolino, R.

    2003-10-01

    This paper presents the results of a high resolution radio imaging survey of 83 of the 118 ultraluminous infrared galaxies (ULIRGs) in the IRAS 1 Jy ULIRG sample. We have observed these ULIRGs at 15 GHz with the Very Large Array (VLA). We find that ~ 75% of Seyferts (both type 1 and 2) and LINERs have radio nuclei which are compact at our 150 mas resolution. The detection rate of H II nuclei is significantly lower (32%); the detections among these are preferentially H II + LINER/Seyfert composite nuclei. Among ULIRGs with multiple optical or near-IR nuclei our observations detected only one (or no) nucleus; in these the radio detection is typically towards the brightest near-IR nucleus. The compactness of the radio sources, the higher detection rates in AGN-type nuclei than H II nuclei, the preferential detection of nuclei with unresolved point sources in the near-IR, the low soft X-ray to nuclear radio luminosity ratio (arguing against thermal emission powering the radio nuclei), and the lack of correlation between radio power and Hα luminosity, all support an origin of the detected radio nuclei in AGN related activity. This result is especially interesting for LINER ULIRGs for which signatures of AGNs have often been ambiguous in other wavebands. Such a high incidence of AGN would provide, for the first time, a large sample in which to study the interplay between AGN, starbursts, and galaxy mergers. Table 1 is also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/a+A/409/115

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Probing large-scale structure with large samples of X-ray selected AGN. I. Baryonic acoustic oscillations

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We investigate the potential of large X-ray-selected AGN samples for detecting baryonic acoustic oscillations (BAO). Though AGN selection in X-ray band is very clean and efficient, it does not provide redshift information, and thus needs to be complemented with an optical follow-up. The main focus of this study is (i) to find the requirements needed for the quality of the optical follow-up and (ii) to formulate the optimal strategy of the X-ray survey, in order to detect the BAO. We demonstrate that redshift accuracy of σ0 = 10-2 at z = 1 and the catastrophic failure rate of ffail ≲ 30% are sufficient for a reliable detection of BAO in future X-ray surveys. Spectroscopic quality redshifts (σ0 = 10-3 and ffail ~ 0) will boost the confidence level of the BAO detection by a factor of ~2. For meaningful detection of BAO, X-ray surveys of moderate depth of Flim ~ few 10-15 erg s-1/cm2 covering sky area from a few hundred to ~ten thousand square degrees are required. The optimal strategy for the BAO detection does not necessarily require full sky coverage. For example, in a 1000 day-long survey by an eROSITA type telescope, an optimal strategy would be to survey a sky area of ~9000 deg2, yielding a ~16σ BAO detection. A similar detection will be achieved by ATHENA+ or WFXT class telescopes in a survey with a duration of 100 days, covering a similar sky area. XMM-Newton can achieve a marginal BAO detection in a 100-day survey covering ~400 deg2. These surveys would demand a moderate-to-high cost in terms the optical follow-ups, requiring determination of redshifts of ~105 (XMM-Newton) to ~3 × 106 objects (eROSITA, ATHENA+, and WFXT) in these sky areas.

  7. 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.

  8. Heavily Obscured AGN with SIMBOL-X

    SciTech Connect

    Ceca, R. Della; Caccianiga, A.; Severgnini, P.

    2009-05-11

    By comparing an optically selected sample of narrow lines AGN with an X-ray selected sample of AGN we have recently derived an estimate of the intrinsic (i.e. before absorption) 2-10 keV luminosity function (XLF) of Compton Thick AGNs. We will use this XLF to derive the number of Compton Thick AGN that will be found in the SIMBOL-X survey(s)

  9. Heavily Obscured AGN with SIMBOL-X

    NASA Astrophysics Data System (ADS)

    Della Ceca, R.; Caccianiga, A.; Severgnini, P.

    2009-05-01

    By comparing an optically selected sample of narrow lines AGN with an X-ray selected sample of AGN we have recently derived an estimate of the intrinsic (i.e. before absorption) 2-10 keV luminosity function (XLF) of Compton Thick AGNs. We will use this XLF to derive the number of Compton Thick AGN that will be found in the SIMBOL-X survey(s).

  10. 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.

  11. A Multi-Frequency Study of an X-ray Selected Sample of AGN II: Line Emission Studies and the X-ray Luminosity Function

    NASA Astrophysics Data System (ADS)

    Grossan, B.; Remillard, R.; Bradt, H.

    1992-12-01

    We carried out a multi-frequency study of a flux-limited (0.95 mu Jy @ 5 keV) sample of 96 emission-line AGN taken from the HEAO-1 LASS/MC survey. Preliminary results of this study were presented at the Jan. 1992 meeting. Here we present new results from line emission and continuum studies and more details regarding the AGN X-ray luminosity functions (XLFs). We find that narrow [OIII] flux correlates well with X-ray flux. This result is consistent with a simple picture where the photoionizing continuum is distributed over a large solid angle in the narrow line region, and is closely related to the X-ray continuum. Broad Balmer lines do not demonstrate a strong correlation with X-ray flux. The UV continuum ( ~ 1400 Angstroms) does not correlate with any optical line emission we measured, but UV variability could have affected this result. In contrast, we find very strong correlations of high-ionization UV broad line fluxes and the simultaneously measured UV continuum. The geometry and/or obscuration effects in the broad line region may therefore be different than those in the narrow line region. A very large spread in the value of broad line Balmer decrements (Hβ /Hα = 0.13 - 0.40) was observed among objects determined to be un-reddened by the lack of an absorption feature at 2175 Angstroms. If there were an intrinsic Balmer decrement for the broad line regions in AGN, the smallest Hβ /Hα values would correspond to extreme values of reddening (E(B-V) > 1 mag). Therefore, we conclude that the broad line Balmer decrement cannot be used in determining continuum reddening in most AGN. We find that the AGN 2-10 keV XLF is roughly a power law, but steepens with increasing luminosity, and turns over below 10(42) erg s(-1) . The XLF of Seyfert 2's resembles a power law from 10(42) - 10(43.5) erg s(-1) , but at higher luminosity, the XLF steepens. In this sample, the cumulative fraction of Seyfert 2's falls rapidly with luminosity, and the overall fraction of Seyfert 2's

  12. What Powers the 12 μm Luminosities in AGNs: Spitzer/IRS Spectroscopic Study of the 12 μm Seyfert Sample

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Huang, J.; Charmandaris, V.

    2009-10-01

    We present a mid-IR study of the 12 μm Seyfert sample, using 5-35 μm low-resolution spectroscopy from Spitzer/IRS. Sources in this sample display a wide variety of spectral shapes. We perform an analysis of the continuum emission, the strength of the Polycyclic Aromatic Hydrocarbon (PAH) emission, as well as fine-structure lines, in order to study the mid-IR properties of the local Seyfert galaxies. We find that the equivalent widths of PAHs decrease with increasing dust temperature. We also propose a method to estimate the AGN contribution to the integrated 12 μm emission of the galaxy.

  13. A long-term study of AGN X-ray variability . Structure function analysis on a ROSAT-XMM quasar sample

    NASA Astrophysics Data System (ADS)

    Middei, R.; Vagnetti, F.; Bianchi, S.; La Franca, F.; Paolillo, M.; Ursini, F.

    2017-03-01

    Context. Variability in the X-rays is a key ingredient in understanding and unveiling active galactic nuclei (AGN) properties. In this band, flux variations occur on short timescales (hours) as well as on larger timescales. While short timescale variability is often investigated in single source studies, only a few works are able to explore flux variation on very long timescales. Aims: This work aims to provide a statistical analysis of the AGN long term X-ray variability. We study variability on the largest time interval ever investigated for the 0.2-2 keV band, up to approximately 20 yr rest-frame for a sample of 220 sources. Moreover, we study variability for 2700 quasars up to approximatley eight years rest-frame in the same (soft) band. Methods: We built our source sample using the 3XMM serendipitous source catalogue data release 5, and data from ROSAT All Sky Survey Bright and Faint source catalogues. To ensure that we selected AGN only, we used the Sloan Digital Sky Survey quasar catalogues data releases 7 and 12. Combining ROSAT and XMM-Newton observations, we investigated variability using the structure function analysis which describes the amount of variability as a function of the lag between the observations. Results: Our work shows an increase of the structure function up to 20 yr. We find no evidence of a plateau in the structure function on these long timescales. Conclusions: The increase of the structure function at long time lags suggests that variability in the soft X-rays can be influenced by flux variations originated in the accretion disk or that they take place in a region large enough to justify variation on such long timescales.

  14. 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.

  15. 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.

  16. AGN feedback in action? - outflows and star formation in type 2 AGNs

    NASA Astrophysics Data System (ADS)

    Woo, Jong-Hak

    2017-01-01

    We present the statistical constraints on the ionized gas outflows and their connection to star formation, using a large sample of ~110,000 AGNs and star-forming galaxies at z < 0.3. First, we find a dramatic difference of the outflow signatures between AGNs and star-forming galaxies based on the [OIII] emission line kinematics. While the [OIII] velocity and velocity dispersion of star forming galaxies can be entirely accounted by the gravitational potential of host galaxies, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. Second, the distribution in the [OIII] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the outflows are AGN-driven. Third, the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. Interestingly, we find that the specific star formation of non-outflow AGNs is much lower than that of strong outflow AGNs, while the star formation rate of strong outflow AGNs is comparable to that of star forming galaxies. We interpret this trend as a delayed AGN feedback as it takes dynamical time for the outflows to suppress star formation in galactic scales.

  17. AGN multi-wavelength identification and host galaxy properties

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    I present results on AGN identification, selection biases, and host galaxy properties at z~2.3 and results on the relation between AGN accretion and star formation activity at z~0.8. In the MOSDEF survey, with a sample of X-ray, IR, and optically selected AGN at z~2.3, using rest-frame optical spectra obtained with the Keck/MOSFIRE instrument, I find clear selection biases in identifying AGN at these wavelengths. There is a strong bias against identifying AGN at any wavelength in low mass galaxies, and an additional bias against identifying IR AGN in the most massive galaxies. While AGN hosts span a wide range of SFR, IR AGN are mainly in less dusty galaxies with relatively higher SFR and optical AGN are in dusty galaxies with relatively lower SFR in our sample. X-ray AGN selection does not display a bias with host SFR. I also consider the relation between the growth of galaxies and their SMBHs using a large sample of X-ray AGN in the PRIMUS survey. I do not find a significant correlation between SFR and AGN instantaneous luminosity. However, I find a weak but significant correlation between the average luminosity of AGN and SFR, which likely reflects that AGN luminosities vary on shorter timescales than host galaxies SFR. My results indicate that AGN are also often hosted by quiescent galaxies, and within both the star-forming and quiescent galaxy populations the probability of hosting an AGN is a power-law distribution as a function of specific accretion rate. However, at a given stellar mass, I find that a star-forming galaxy is ~2-3 times 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, while in quiescent galaxies increases with SFR.

  18. Accretion Rate: An Axis Of Agn Unification

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; Impey, C. D.; Kelly, B. C.

    2011-01-01

    We show how accretion rate governs the physical properties of broad-line, narrow-line, and lineless active galactic nuclei (AGNs). We avoid the systematic errors plaguing previous studies of AGN accretion rate by using accurate accretion luminosities from well-sampled multiwavelength SEDs from the Cosmic Evolution Survey (COSMOS), and accurate black hole masses derived from virial scaling relations (for broad-line AGNs) or host-AGN relations (for narrow-line and lineless AGNs). In general, broad emission lines are present only at the highest accretion rates (L/L_Edd>0.01), and these rapidly accreting AGNs are observed as broad-line AGNs or possibly as obscured narrow-line AGNs. Narrow-line and lineless AGNs at lower specific accretion rates (L/L_Edd<0.01) are unobscured and yet lack a broad line region. The disappearance of the broad emission lines is caused by an expanding radiatively inefficient accretion flow (RIAF) at the inner radius of the accretion disk. The presence of the RIAF also drives L/L_Edd<0.01 narrow-line and lineless AGNs to be 10-100 times more radio-luminous than broad-line AGNs, since the unbound nature of the RIAF means it is easier to form a radio outflow. The IR torus signature also tends to become weaker or disappear from L/L_Edd<0.01 AGNs, although there may be additional mid-IR synchrotron emission associated with the RIAF. Together these results suggest that specific accretion rate is an important physical "axis" of AGN unification, described by a simple model.

  19. 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

  20. 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.

  1. Spectral Energy Distributions of Quasars and AGN

    NASA Astrophysics Data System (ADS)

    Wilkes, B.

    2004-06-01

    Active Galactic Nuclei (AGN) are multiwavelength emitters. To have any hope of understanding them, or even to determine their energy output, we must observe them in multiple wavebands using many telescopes. I will review what we have learned from broad-band observations of relatively bright, low-redshift AGN over the past ˜ 15 years. AGN can be found at all wavelengths but each provides a different view of the intrinsic population, often with little overlap between samples selected in different wavebands. I look forward to the full view of the intrinsic population which we will obtain over the next few years with surveys using today's new, sensitive observatories. These surveys are already finding enough new and different AGN candidates to pose the question ``What IS an AGN?".

  2. The BAT AGN Spectroscopic Survey (BASS)

    NASA Astrophysics Data System (ADS)

    Koss, Michael; Trakhtenbrot, Benny; Ricci, Claudio; Lamperti, Isabella; Oh, Kyuseok; Berney, Simon; Schawinski, Kevin; Balokovic, Mislav; Baronchelli, Linda; Gehrels, Neil; Stern, Daniel; Mushotzky, Richard; Veilleux, Sylvain; Ueda, Yoshihiro; Crenshaw, D. Michael; Harrison, Fiona; Fischer, Travis C.; Treister, Ezequiel; BASS Team; Swift BAT Team

    2017-01-01

    We present the Swift BAT AGN Spectroscopic Survey (BASS) and discus the first four papers. The catalog represents an unprecedented census of hard-X-ray selected AGN in the local universe, with ~90% of sources at z<0.2. Starting from an all-sky catalog of AGN detected based on their 14-195 keV flux from the 70-month Swift/BAT catalog, we analyze a total of 1279 optical spectra, taken from twelve dierent telescopes, for a total of 642 spectra of unique AGN. We present the absorption and emission line measurements as well as black hole masses and accretion rates for the majority of obscured and un-obscured AGN (473), representing more than a factor of 10 increase from past studies. Consistent with previous surveys, we find an increase in the fraction of un-obscured (type 1) AGN, as measured from broad Hbeta and Halpha, with increasing 14-195 keV and 2-10 keV luminosity. We find the FWHM of the emission lines to show broad agreement with the X-ray obscuration measurements. Compared to narrow line AGN in the SDSS, the X-ray selected AGN in our sample with emission lines have a larger fraction of dustier galaxies suggesting these types of galaxies are missed in optical AGN surveys using emission line diagnostics. Additionally, we discuss follow-on efforts to study the variation of [OIII] to Xray measurements, a new method to measure accretion rates from using line ratios, a sample of 100 AGN observed with NIR spectroscopy, and an effort to measure the accretion rates and obscuration with merger stage in a subsample of mergers.

  3. Star Formation and AGN activity of X-ray selected AGN host galaxies in the Chandra-COSMOS Legacy Survey

    NASA Astrophysics Data System (ADS)

    Suh, Hyewon

    2017-01-01

    One of the ongoing issues for understanding the galaxy formation and evolution is how active galactic nuclei (AGNs) affect the growth of their host galaxies. We investigate the correlations between AGN activity and star formation properties of a large sample of ~3700 X-ray selected AGNs over a wide range of luminosities (42 < log Lx < 45) up to z~5 in the Chandra-COSMOS Legacy Survey. We perform a multi-component modeling from the far-infrared, when available, to the near-UV using AGN emission from the big-blue-bump (for Type 1 AGNs), a nuclear dust torus model, a galaxy model and a starburst component for the spectral energy distributions (SEDs). Through detailed analysis of SEDs, we derive AGN host galaxy properties, such as stellar masses, star formation rates (SFRs), and AGN luminosities. We find that AGN host galaxies have, on average, similar SFRs compared to the normal star-forming main sequence galaxies, suggesting no significant enhancement or quenching of star formation. The average SFR of AGN host galaxies shows a flat distribution in bins of AGN luminosity, consistent with recent ideas that the shorter variability timescale of AGN compared to star formation can lead to a flat relationship between the SFR and black hole accretion rates. Our results suggest that both star formation and nuclear activity in the majority of AGN host galaxies might be driven more by internal secular processes at z<3, implying that they have substantially grown at much earlier epoch.

  4. 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.

  5. Spitzer's contribution to the AGN population

    NASA Astrophysics Data System (ADS)

    Donley, Jennifer Lynn

    2009-06-01

    Using large multiwavelength datasets, we study obscured AGN in the distant universe that have been missed via traditional selection techniques (e.g. UV/ optical/X-ray). To do so, we take particular advantage of the mid-IR, which is minimally affected by obscuration. We first select as AGN candidates those objects whose radio emission is significantly brighter, relative to the mid-IR, than would be predicted by the well known radio/infrared correlation, indicating that the radio emission originates in the central engine. We find that of the 27 such sources identified in the CDF-N, 60% lack solid X-ray detections and 25% lack even 2s X-ray emission. The absorbing columns of the faint X-ray-detected objects indicate that they are obscured but unlikely to be Compton thick, whereas the radio-excess AGN which are X-ray non-detected are Compton-thick candidates. We similarly use the infrared emission to select IRAC (3.6-8.0 mm) power-law AGN. In these luminous AGN, the hot dust emission from the AGN fills in the gap in a galaxy's SED between the 1.6 mm stellar bump and the long-wavelength dust emission feature. While sources selected in this way are more luminous than the radio-excess AGN, we find a similar X-ray detection fraction. Of the 62 power- law galaxies in the CDF-N, only 55% are detected in the X-ray, and 15% lack evidence for even weak 2s X-ray emission. A study of their X-ray properties indicates that ~ 75% are obscured. Finally, we test IRAC color-color and infrared-excess selection criteria. We find that while these selection techniques identify a number of obscured AGN, they may also select a significant number of star-forming galaxies. By combining only the secure AGN candidates selected via all methods discussed above, we estimate that the addition of Spitzer-selected AGN candidates to the deepest X-ray selected AGN samples directly increases the number of known AGN by 54-77%, and implies a total increase to the number of AGN of 71-94%.

  6. Study of the mid-infrared properties of obscured AGN

    NASA Astrophysics Data System (ADS)

    Severgnini, P.; Caccianiga, A.; della Ceca, R.

    2008-10-01

    The comprehension of the physical properties of obscured AGNs is one of the main goals of the high energy astronomy given their key role in tracing the accretion history of the Universe. Although X-ray and infrared data of AGN with a different level of absorption could provide a direct tool to test the predictions of the AGN models, only few sparse SED of obscured AGN are available so far. We present here the results obtained from Spitzer observations of a statistically complete sample of obscured AGN drawn from the XMM-Newton Hard Bright Sample. This is the largest hard X-ray sample with a complete spectroscopic identification. The Spitzer data, combined with good X-ray and optical spectroscopic data, has allowed us to define powerful diagnostic plots to select heavily obscured AGNs and to build up their spectral energy distributions.

  7. Fading AGN Candidates: AGN Histories and Outflow Signatures

    NASA Astrophysics Data System (ADS)

    Keel, William C.; Lintott, Chris J.; Maksym, W. Peter; Bennert, Vardha N.; Chojnowski, S. Drew; Moiseev, Alexei; Smirnova, Aleksandrina; Schawinski, Kevin; Sartori, Lia F.; Urry, C. Megan; Pancoast, Anna; Schirmer, Mischa; Scott, Bryan; Showley, Charles; Flatland, Kelsi

    2017-02-01

    We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Qion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Qion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2 × 104 yr before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission

  8. The Angular Clustering of WISE-Selected AGN: Different Haloes for Obscured and Unobscured AGN

    NASA Astrophysics Data System (ADS)

    Yan, Lin

    2015-08-01

    We calculate the angular correlation function for a sample of 170,000 AGN extracted from the Wide-field Infrared Survey Explorer (WISE) catalog, selected to have red mid-IR colors (W1 - W2 > 0.8) and 4.6 micron flux densities brighter than 0.14 mJy). The sample is expected to be >90% reliable at identifying AGN, and to have a mean redshift of z=1.1. In total, the angular clustering of WISE-AGN is roughly similar to that of optical AGN. We cross-match these objects with the photometric SDSS catalog and distinguish obscured sources with (r - W2) > 6 from bluer, unobscured AGN. Obscured sources present a higher clustering signal than unobscured sources. Since the host galaxy morphologies of obscured AGN are not typical red sequence elliptical galaxies and show disks in many cases, it is unlikely that the increased clustering strength of the obscured population is driven by a host galaxy segregation bias. By using relatively complete redshift distributions from the COSMOS survey, we find obscured sources at mean redshift z=0.9 have a bias of b = 2.9 \\pm 0.6 and are hosted in dark matter halos with a typical mass of log(M/M_odot)~13.5. In contrast, unobscured AGN at z~1.1 have a bias of b = 1.6 \\pm 0.6 and inhabit halos of log(M/M_odot)~12.4. These findings suggest that obscured AGN inhabit denser environments than unobscured AGN, and are difficult to reconcile with the simplest AGN unification models, where obscuration is driven solely by orientation.

  9. Probing Agn Accretion Physics With Kepler

    NASA Astrophysics Data System (ADS)

    Vogeley, Michael

    We propose to use Kepler observations of a sample of ~100 supermassive black holes at the centers of galaxies (Active Galactic Nuclei; AGN) to test models for accretion physics, to study the relationship between variability and other AGN properties, and to guide methods for detecting and classifying AGN in future time-domain surveys. AGN exhibit optical brightness fluctuations on timescales from below an hour up to many years. These fluctuations are determined by the physics of accretion of matter onto black holes from their galactic environment. By observing variability on timescales down to below an hour, Kepler probes the accretion region on length scales that are too small to be directly imaged using conventional telescopes. Data from this unique time- domain telescope now allow us to test competing models for accretion physics that make different predictions for the statistics of variability. Preliminary work provides strong evidence that models of AGN variability that work on long timescale data are not adequate to describe the full range of fluctuation timescales probed by Kepler. We will analyze the light curves of Kepler AGN that span a large range of luminosity and AGN type, thus allowing study of the relationship between variability and other physical properties. Using methods developed and tested by the Kepler team, we will perform custom post-processing of these light curves to remove known systematics. Statistical analyses of the AGN light curves will include estimation of the Structure Function, which quantifies the correlations of brightness fluctuations, and maximum likelihood light curve reconstruction. Competing models for the stochastic behavior of AGN will be tested to evaluate which models best describe variability of AGN over the full range of timescales probed by Kepler. Correlations between the stochastic model parameters and physical parameters will provide new methods for classification of AGN from their variability and aid in

  10. 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.

  11. 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.

  12. Properties And Evolution Of Radio-AGN Hosts Since z ~ 4

    NASA Astrophysics Data System (ADS)

    Delvecchio, Ivan; Smolčić, V.; Zamorani, G.; Del P. Lagos, C.; Berta, S.; Delhaize, J.; Baran, N.; Alexander, D.; Rosario, D.; et al.

    2016-10-01

    We analyse the multi-wavelength properties of about 7500 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<1.5, 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.

  13. 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.

  14. 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.

  15. Satellites of Radio AGN in SDSS: Insights into AGN Triggering and Feedback

    NASA Astrophysics Data System (ADS)

    Pace, Cameron; Salim, Samir

    2014-04-01

    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 & 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.

  16. Identifying Distant AGNs

    NASA Astrophysics Data System (ADS)

    Trouille, Laura; Barger, Amy; Tremonti, Christy

    2014-07-01

    The Baldwin, Phillips, and Terlevich emission-line ratio diagnostic ([OIII]/Hβ versus [NII]/Hα, hereafter BPT diagram) efficiently separates galaxies whose signal is dominated by star formation (BPT-SF) from those dominated by AGN activity (BPT-AGN). Yet the BPT diagram is limited to z<0.5, the redshift at which [NII]λ6584 leaves the optical spectral window. Using the Sloan Digital Sky Survey (SDSS), we construct a new diagnostic, or TBT diagram, that is based on rest-frame g-z color, [NeIII]λ3869, and [OII]λλ3726+3729 and can be used for galaxies out to z<1.4. The TBT diagram identifies 98.7% of the SDSS BPT-AGN as TBT-AGN and 97% of the SDSS BPT-SF as TBT-SF. Furthermore, it identifies 97% of the OPTX Chandra X-ray selected AGNs as TBT-AGN. This is in contrast to the BPT diagram, which misidentifies 20% of X-ray selected AGNs as BPT-SF.

  17. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

    2017-01-01

    Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

  18. Obscured AGN Accretion Across Cosmic Time

    NASA Astrophysics Data System (ADS)

    Coil, Alison

    We propose to combine data from XMM-Newton, the Chandra X-ray Observatory, and the Spitzer Space Telescope with ground-based optical spectroscopy from Keck and Magellan to measure the relationship between AGN obscuration and accretion activity over the bulk of cosmic history. This work will establish the prominence of both obscured and unobscured growth phases of black holes and shed light on the processes that trigger and fuel AGN as a function of time. We will complete three complementary projects that focus on a) understanding the completeness and biases of AGN selection at mid-IR versus X-ray wavelengths, b) tracing optical obscuration as a function of luminosity and redshift, and c) measuring the distribution and evolution of X-ray absorption of AGN. We will undertake a study of AGN demographics comparing selection techniques at three different wavelengths: mid-IR selection using data from the Spitzer Space Telescope, X- ray selection using data from the XMM-Newton and Chandra satellites, and broad-line optical selection using PRIMUS spectroscopy. We will determine the overlap and uniqueness of samples created using each method, to quantify the completeness and biases inherent in AGN selection at each wavelength. This will lead to a constraint on the fraction of heavily obscured, Compton-thick AGN to z~1. To study the optical obscuration of AGN, we will use three recently-completed spectroscopic surveys -- PRIMUS, DEEP2, and our own Keck program -- to robustly determine the ratio of unobscured (broad-line) to obscured (non--broad-line) X-ray selected AGN as a function of luminosity from z~0.2 to z~3. We will utilize the well- understood selection functions and characterize the AGN completeness of each survey as a function of redshift, magnitude, and obscuration properties. This will allow us to correct for a variety of observational effects to measure the underlying joint redshift- and luminosity-dependence of optical obscuration, which has direct implications

  19. Hiding in plain sight - recovering clusters of galaxies with the strongest AGN in their cores

    NASA Astrophysics Data System (ADS)

    Green, T. S.; Edge, A. C.; Ebeling, H.; Burgett, W. S.; Draper, P. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

    2017-03-01

    A key challenge in understanding the feedback mechanism of active galactic nucleus (AGN) in Brightest Cluster Galaxies (BCGs) is the inherent rarity of catching an AGN during its strong outburst phase. This is exacerbated by the ambiguity of differentiating between AGN and clusters in X-ray observations. If there is evidence for an AGN then the X-ray emission is commonly assumed to be dominated by the AGN emission, introducing a selection effect against the detection of AGN in BCGs. In order to recover these 'missing' clusters, we systematically investigate the colour-magnitude relation around some ∼3500 ROSAT All-Sky Survey selected AGN, looking for signs of a cluster red sequence. Amongst our 22 candidate systems, we independently rediscover several confirmed systems, where a strong AGN resides in a central galaxy. We compare the X-ray luminosity to red sequence richness distribution of our AGN candidate systems with that of a similarly selected comparison sample of ∼1000 confirmed clusters and identify seven 'best' candidates (all of which are BL Lac objects), where the X-ray flux is likely to be a comparable mix between cluster and AGN emission. We confirm that the colours of the red sequence are consistent with the redshift of the AGN, that the colours of the AGN host galaxy are consistent with AGN, and, by comparing their luminosities with those from our comparison clusters, confirm that the AGN hosts are consistent with BCGs.

  20. 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.

  1. 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.

  2. The Role of Star Formation and AGN in Dust Heating of z=0.3-2.8 Galaxies - II. Informing IR AGN Fraction Estimates through Simulations

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    A key question in extragalactic studies is the determination of the relative roles of stars and active galactic nuclei (AGNs) in powering dusty galaxies at z ˜ 1-3 where the bulk of star formation and AGN activity took place. In Paper I, we present a sample of 336 24 μm selected (Ultra)Luminous Infrared Galaxies, (U)LIRGs, at z˜ 0.3-2.8, where we focus on determining the AGN contribution to the IR luminosity. Here, we use hydrodynamic simulations with dust radiative transfer of isolated and merging galaxies to investigate how well the simulations reproduce our empirical IR AGN fraction estimates and determine how IR AGN fractions relate to the UV-mm AGN fraction. We find that: (1) IR AGN fraction estimates based on simulations are in qualitative agreement with the empirical values when host reprocessing of the AGN light is considered; (2) for star-forming galaxy (SFG)-AGN composites our empirical methods may be underestimating the role of AGN, as our simulations imply \\gt 50 % AGN fractions, ˜ 3× higher than previous estimates; (3) 6% of our empirically classified SFGs have AGN fractions ≳50%. While this is a small percentage of SFGs, if confirmed it would imply that the true number density of AGNs may be underestimated; (4) this comparison depends on the adopted AGN template—those that neglect the contribution of warm dust lower the empirical fractions by up to two times; and (5) the IR AGN fraction is only a good proxy for the intrinsic UV-mm AGN fraction when the extinction is high ({A}V≳ 1 or up to and including coalescence in a merger).

  3. Combining Chandra Observations and Near-Infrared Imaging to Search for Dual AGNs Among Double-Peaked [O III] SDSS AGN

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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. We studied a sample of double-peaked SDSS [O III] AGNs using Keck 2 Laser Guide Star Adaptive Optics assisted imaging to find that 30% of double-peaked SDSS AGNs have two spatial components within a 3" radius. However, the identity of the companion object is not revealed with imaging; X-ray observations can confirm these galaxy pairs as systems containing two AGNs. We performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs with a possible near-infrared companion 1-3" away. Using our observations and 8 archival observations of additional candidate dual AGNs, 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. Additionally, we can compare our near-IR spatially double candidates with 7 double-peaked [O III] SDSS AGNs that are spatially single in our near-IR imaging and have archival Chandra ACIS-S observations. 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

  4. 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.

  5. AGN Host Galaxy Properties And Mass Function

    NASA Astrophysics Data System (ADS)

    Bongiorno, Angela

    2016-10-01

    Supermassive black hole growth, nuclear activity, and galaxy evolution have been found to be closely related. In the context of AGN-galaxy coevolution, I will discuss about the relation found between the host galaxy properties and the central BH and I will present the latest determination of the host galaxy stellar mass function (HGMF), and the specific accretion rate distribution function (SARDF), derived from the XMM-COSMOS sample up to z˜2.5, with particular focus on AGN feedback as possible responsible mechanism for galaxy quenching.

  6. 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.

  7. 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.

  8. 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}.

  9. Measuring Feedback in Nearby AGN

    NASA Astrophysics Data System (ADS)

    Crenshaw, D. M.; Fischer, T. C.; Kraemer, S. B.; Schmitt, H. R.; Turner, T. J.

    2012-08-01

    We investigate the impact of feedback from outflowing UV and X-ray absorbers in nearby (z < 0.04) AGN. From studies of the kinematics, physical conditions, and variability of the absorbers in the literature, we calculate the possible ranges in total mass outflow rate (Ṁout) and kinetic luminosity (LK) for each AGN, summed over all of the absorbers. These calculations make use of values (or limits) for the radial locations of the absorbers determined from variability, excited-state absorption, or other considerations. From a sample of 10 Seyfert 1 galaxies with detailed photoionization models for their absorbers, we find that 7 have sufficient constraints on the absorber locations to determine Ṁout and LK. The 6 Seyfert 1s with moderate bolometric luminosities (Lbol = 1043 - 1045 ergs s-1) all have mass outflow rates that are 10 - 1000 times the mass accretion rates needed to generate their observed luminosities, indicating that most of the mass outflow originates from outside the inner accretion disk. Three of these (NGC 4051, NGC 3516, and NGC 3783) have LK in the range 0.5 - 5% Lbol, which is the range typically required by feedback models for efficient self-regulation of black-hole and galactic bulge growth. The other three (NGC 5548, NGC 4151, and NGC 7469) have LK > 0.1%Lbol, although these values may increase if radial locations can be determined for more of the absorbers. We conclude that the outflowing UV and X-ray absorbers in moderate-luminosity AGN have the potential to deliver significant feedback to their environments.

  10. 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.

  11. 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.

  12. The evolution of obscured AGN

    NASA Astrophysics Data System (ADS)

    Brightman, Murray

    2012-09-01

    We present results on the evolution of Compton thick AGN with redshift, and the nature of this obscuration, important for understanding the accretion history of the universe and for AGN unification schemes. We use lessons learned from spectral complexity of local AGN (Brightman & Nandra 2012) and up to date spectral models of heavily absorbed AGN, which take into account Compton scattering, self consistent Fe Ka modeling and the geometry of the circumnuclear material (Brightman & Nandra 2011), to optimise our identification of Compton thick AGN and understanding of the obscuring material. Results from the Chandra Deep Field South are presented (Brightman & Ueda, 2012), which show an increasing fraction of CTAGN with redshift and that most heavily obscured AGN are geometrically deeply buried in material, as well as new results from and extension of this study to AEGIS-XD and Chandra-COSMOS survey, which aim to fully characterise the dependence of heavy AGN obscuration on redshift and luminosity.

  13. 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°.

  14. 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.

  15. The AGN Luminosity Fraction in Galaxy Mergers

    NASA Astrophysics Data System (ADS)

    Dietrich, Jeremy; Weiner, Aaron; Ashby, Matthew; Martinez-Galarza, Juan Rafael; Smith, Howard Alan

    2017-01-01

    Galaxy mergers are key events in galaxy evolution, generally triggering massive starbursts and AGNs. However, in these chaotic systems, it is not yet known what fraction each of these two mechanisms contributes to the total luminosity. Here we measure and model spectral energy distributions (SEDs) using the Code for Investigating Galaxy Emission (CIGALE) in up to 33 broad bands from the UV to the far-IR for 23 IR-luminous galaxies to estimate the fraction of the bolometric IR luminosity that can be attributed to the AGN. The galaxies are split nearly evenly into two subsamples: late-stage mergers, found in the IRAS Revised Bright Galaxy Sample or Faint Source Catalog, and early-stage mergers found in the Spitzer Interacting Galaxy Sample. We find that the AGN contribution to the total IR luminosity varies greatly from system to system, from 0% up to ~90%, but is substantially greater in the later-stage and brighter mergers. This is consistent with what is known about galaxy evolution and the triggering of AGNs.The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. 1262851, and by the Smithsonian Institution.

  16. AGN Variability: Probing Black Hole Accretion

    NASA Astrophysics Data System (ADS)

    Moreno, Jackeline; O'Brien, Jack; Vogeley, Michael S.; Richards, Gordon T.; Kasliwal, Vishal P.

    2017-01-01

    We combine the long temporal baseline of Sloan Digital Sky Survey (SDSS) for quasars in Stripe 82 with the high precision photometry of the Kepler/K2 Satellite to study the physics of optical variability in the accretion disk and supermassive black hole engine. We model the lightcurves directly as Continuous-time Auto Regressive Moving Average processes (C-ARMA) with the Kali analysis package (Kasliwal et al. 2016). These models are extremely robust to irregular sampling and can capture aperiodic variability structure on various timescales. We also estimate the power spectral density and structure function of both the model family and the data. A Green's function kernel may also be estimated for the resulting C-ARMA parameter fit, which may be interpreted as the response to driving impulses such as hotspots in the accretion disk. We also examine available spectra for our AGN sample to relate observed and modelled behavior to spectral properties. The objective of this work is twofold: to explore the proper physical interpretation of different families of C-ARMA models applied to AGN optical flux variability and to relate empirical characteristic timescales of our AGN sample to physical theory or to properties estimated from spectra or simulations like the disk viscosity and temperature. We find that AGN with strong variability features on timescales resolved by K2 are well modelled by a low order C-ARMA family while K2 lightcurves with weak amplitude variability are dominated by outliers and measurement errors which force higher order model fits. This work explores a novel approach to combining SDSS and K2 data sets and presents recovered characteristic timescales of AGN variability.

  17. X-ray-selected AGNs near bright galaxies

    NASA Technical Reports Server (NTRS)

    Stocke, John T.; Schneider, Peter; Morris, Simon L.; Gioia, Isabella M.; Maccacaro, Tommaso

    1987-01-01

    Among the numerous low-redshift low-luminosity X-ray sources discovered with the Einstein Observatory, ten AGNs were identified that are projected within three optical diameters of bright (V less than 18) foreground galaxies. These AGNs near galaxies have significantly higher redshifts than the sample as a whole. This discovery is interpreted in terms of gravitational 'microlensing' in which stars in the foreground galaxy have significantly brightened the X-ray emission from these higher redshift AGNs, allowing their detection. It is suggested that microlensing may be responsible for a significant alteration of the inherent QSO luminosity function.

  18. 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.

  19. The Lick AGN Monitoring Project 2016: Extending Reverberation Mapping to Higher Luminosity AGNs

    NASA Astrophysics Data System (ADS)

    U, Vivian; LAMP2016 Collaboration

    2017-01-01

    The technique of reverberation mapping has been used to estimate virial black hole masses and, more fundamentally, to probe the broad line region structure in Seyfert I galaxies. Efforts from the previous Lick AGN Monitoring Project (LAMP) campaigns and other studies to date have culminated in a large sample of reverberation mapped AGNs and measurements of their black hole masses, which in turn enabled major improvement to various AGN scaling relations. However, the high-luminosity end of such relations remains poorly constrained; this is because of observational challenges presented by the weaker continuum flux variations and longer time dilation in these sources. To this end, we have initiated a new LAMP2016 campaign to target AGNs with luminosities of 10^44 erg/s, with predicted H-beta lags of ~20 - 60 days or black hole masses of 10^7 - 10^8.5 Msun. Designed to monitor ~20 AGNs biweekly from Spring 2016 through Winter 2017 with the Kast spectrograph on the 3-m Shane Telescope at Lick Observatory, we aim to probe luminosity-dependent trends in broad line region structure and dynamics, improve calibrations for single-epoch estimates of high-redshift quasar black hole masses, and test photoionization models for the radially-stratified structure of the broad line region. In this talk, I will present the overview and scope of LAMP2016 and show preliminary results from our ongoing campaign.

  20. AGES: THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Kochanek, C. S.; Eisenstein, D. J.; Caldwell, N.; Jones, C.; Murray, S. S.; Forman, W. R.; Green, P.; Cool, R. J.; Assef, R. J.; Eisenhardt, P.; Stern, D.; Jannuzi, B. T.; Dey, A.; Brown, M. J. I.; Gonzalez, A. H.

    2012-05-01

    The AGN and Galaxy Evolution Survey (AGES) is a redshift survey covering, in its standard fields, 7.7 deg{sup 2} of the Booetes field of the NOAO Deep Wide-Field Survey. The final sample consists of 23,745 redshifts. There are well-defined galaxy samples in 10 bands (the B{sub W} , R, I, J, K, IRAC 3.6, 4.5, 5.8, and 8.0 {mu}m, and MIPS 24 {mu}m bands) to a limiting magnitude of I < 20 mag for spectroscopy. For these galaxies, we obtained 18,163 redshifts from a sample of 35,200 galaxies, where random sparse sampling was used to define statistically complete sub-samples in all 10 photometric bands. The median galaxy redshift is 0.31, and 90% of the redshifts are in the range 0.085 < z < 0.66. Active galactic nuclei (AGNs) were selected as radio, X-ray, IRAC mid-IR, and MIPS 24 {mu}m sources to fainter limiting magnitudes (I < 22.5 mag for point sources). Redshifts were obtained for 4764 quasars and galaxies with AGN signatures, with 2926, 1718, 605, 119, and 13 above redshifts of 0.5, 1, 2, 3, and 4, respectively. We detail all the AGES selection procedures and present the complete spectroscopic redshift catalogs and spectral energy distribution decompositions. Photometric redshift estimates are provided for all sources in the AGES samples.

  1. 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".

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Fraction of the X-ray selected AGNs with optical emission lines in galaxy groups

    NASA Astrophysics Data System (ADS)

    Li, Feng; Yuan, Qirong; Bian, Weihao; Chen, Xi; Yan, Pengfei

    2017-04-01

    Compared with numerous X-ray dominant active galactic nuclei (AGNs) without emission-line signatures in their optical spectra, the X-ray selected AGNs with optical emission lines are probably still in the high-accretion phase of black hole growth. This paper presents an investigation on the fraction of these X-ray detected AGNs with optical emission-line spectra in 198 galaxy groups at z<1 in a rest frame 0.1-2.4 keV luminosity range 41.3 < log(LX/erg s^{-1}) < 44.1 within the Cosmological Evolution Survey (COSMOS) field, as well as its variations with redshift and group richness. For various selection criteria of member galaxies, the numbers of galaxies and the AGNs with optical emission lines in each galaxy group are obtained. It is found that, in total 198 X-ray groups, there are 27 AGNs detected in 26 groups. AGN fraction is on average less than 4.6 (±1.2)% for individual groups hosting at least one AGN. The corrected overall AGN fraction for whole group sample is less than 0.98 (±0.11) %. The normalized locations of group AGNs show that 15 AGNs are found to be located in group centers, including all 6 low-luminosity group AGNs (L_{ 0.5-2 keV} < 10^{42.5} erg s^{-1}). A week rising tendency with z are found: overall AGN fraction is 0.30-0.43% for the groups at z<0.5, and 0.55-0.64% at 0.5 < z < 1.0. For the X-ray groups at z>0.5, most member AGNs are X-ray bright, optically dull, which results in a lower AGN fractions at higher redshifts. The AGN fraction in isolated fields also exhibits a rising trend with redshift, and the slope is consistent with that in groups. The environment of galaxy groups seems to make no difference in detection probability of the AGNs with emission lines. Additionally, a larger AGN fractions are found in poorer groups, which implies that the AGNs in poor groups might still be in the high-accretion phase, whereas the AGN population in rich clusters is mostly in the low-accretion, X-ray dominant phase.

  8. The Changing Looks of AGN

    NASA Astrophysics Data System (ADS)

    LaMassa, S.

    2015-09-01

    According to the AGN unification model, the difference between Type 1 and Type 2 AGN is explained by the orientation of a circumnuclear obscuring torus to the observer's line of sight. Observations of seemingly anomalous sources challenge this theory. A handful of AGN have been discovered which have transitioned from Type 1, with strong, prominent broad-emission lines, to Type 1.8 or 1.9, with weak broad components to only H-alpha and/or H-beta, or vice versa. The rate of discovery of these objects has increased this past year thanks to the Sloan Digital Sky Survey BOSS and TDSS surveys which have repeated spectroscopic observations of AGN. While in some cases this transition can be explained by circumnuclear clouds eclipsing the broad line region, it seems clear that stochastic accretion is responsible for other changing-look AGN. In this talk, I will discuss the changing-look AGN discovered thus far and the implications these objects have for AGN unification and the intermittency of AGN activity.

  9. VizieR Online Data Catalog: AGN from the RASS (Bade+, 1995)

    NASA Astrophysics Data System (ADS)

    Bade, N.; Fink, H. H.; Engels, D.; Voges, W.; Hagen, H.-J.; Wisotzki, L.; Reimers, D.

    1995-02-01

    This paper presents long slit CCD spectroscopy and X-ray data of 283 AGN detected in the ROSAT-All Sky Survey (RASS). Basis of the sample is the pre-identification of 4651 RASS sources on 134 sky fields (covering in total ~3500sq.deg.). The 283 presented AGN were selected from 1253 AGN candidates resulting from the pre-identification work. (3 data files).

  10. 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.

  11. 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.

  12. 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; ...

    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

  13. Merger-driven Fueling of Active Galactic Nuclei: Six Dual and Offset AGNs Discovered with Chandra and Hubble Space Telescope Observations

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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 Δ 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 Δ 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. 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.

  14. 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.

  15. Multiwavelength Number Counts of AGN in the GOODS Fields

    NASA Astrophysics Data System (ADS)

    Urry, C. M.; Treister, E.; Chatzichristou, E. T.; Van Duyne, J.; Bauer, F. E.; Alexander, D. M.; Koekemoer, A. M.; Moustakas, L. A.; Brandt, W. N.; Grogin, N. A.; Bergeron, J.; Stern, D.; Chary, R.-R.; Conselice, C. J.; Cristiani, S.

    2004-05-01

    We model the X-ray, optical, and far-infrared flux distributions of AGN in the GOODS fields, starting from hard X-ray luminosity functions and spectral energy distributions appropriate to the unified scheme for AGN. The deep optical counts measured from HST ACS images can be well explained by a unified scheme that postulates roughly 3 times as many obscured as unobscured AGN. This scenario is consistent with the observed spectroscopic and photometric redshift distributions of the GOODS AGN once selection effects are considered. The previously reported discrepancy between observed spectroscopic redshift distributions and the predictions of population synthesis models for the X-ray background (which include a similarly large number of obscured AGN) is explained by bias against the most heavily obscured AGN in both X-ray surveys and optical spectroscopic samples. We present the model predictions for the number counts of AGN in the Spitzer MIPS 24 micron and IRAC 3.6-8 micron bands. The GOODS Spitzer observations will verify whether large numbers of obscured AGN are indeed present in the early Universe; these will be very bright far-infrared sources, including some, missed by X-ray observations, that look like ultraluminous infrared galaxies. Based on observations obtained with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc, under NASA contract NAS5-26555. This work was supported by NASA grants HST-GO-09425(.01-A,.13-A,.26-A); NSF CAREER award AST 99-83783; NASA contract number 1224666 issued by JPL/Caltech under NASA contract 1407; ASI grant I/R/088/02; and a Royal Society University Research Fellowship.

  16. 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.

  17. Lyman continuum leaking AGN in the SSA22 field

    NASA Astrophysics Data System (ADS)

    Micheva, Genoveva; Iwata, Ikuru; Inoue, Akio K.

    2017-02-01

    Subaru/SuprimeCam narrow-band photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 active galactic nuclei (AGNs). Two show offsets and likely have stellar LyCin nature or are foreground contaminants. The remaining two LyC candidates are type I AGN. We argue that the average LyC escape fraction of high-redshift, low-luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of 2 lower than values obtained assuming fesc = 1. Comparing to recent Ly α forest measurements, AGNs at redshift z ˜ 3 make up at most ˜12 per cent and as little as ˜5 per cent of the total ionizing budget. Our results suggest that AGNs are unlikely to dominate the ionization budget of the Universe at high redshifts.

  18. 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.

  19. A Method of Identifying AGNs Based on Emission-Line Excess and the Nature of Low-Luminosity AGNs in the Sloan Digital Sky Survey. II. The Nature of Low-Luminosity AGNs

    NASA Astrophysics Data System (ADS)

    Tanaka, Masayuki

    2012-04-01

    We have developed a new method of identifying active galactic nuclei (AGNs) and studied the nature of low-luminosity AGNs in the Sloan Digital Sky Survey. This is the latter part of a series of papers in which we consider correlations between the AGN activities and the host-galaxy properties. Based on a sample of AGNs identified by a new method developed in the former part (2012, PASJ, 64, 36), we found that AGNs typically show extinction of τV = 1.2, and exhibit a wide range of ionization levels. The finding of ionization levels motivated us to use [O II] + [O III] as an indicator of AGN power. We found that AGNs are preferentially located in massive, red, early-type galaxies. Taking into account a selection bias of the Oxygen-excess method, we showed that strong AGNs are located in active star-forming galaxies, and that rapidly growing super-massive black holes are located in rapidly growing galaxies, which clearly shows the coevolution of super-massive black holes and their host galaxies. This is a surprising phenomenon, given that the growths of black holes and host galaxies occur on their respective physical scales which are very different. Interestingly, the AGN power does not strongly correlate with the host-galaxy mass. It seems that the mass works as a ``switch'' for activating AGNs. The absence of AGNs in low-mass galaxies might be due to the absence of super-massive black holes there, but a dedicated observation of the nuclear region of nearby low-mass galaxies would be necessary to obtain a deeper insight into it.

  20. Host galaxies of luminous z ∼ 0.6 quasars: major mergers are not prevalent at the highest AGN luminosities

    NASA Astrophysics Data System (ADS)

    Villforth, C.; Hamilton, T.; Pawlik, M. M.; Hewlett, T.; Rowlands, K.; Herbst, H.; Shankar, F.; Fontana, A.; Hamann, F.; Koekemoer, A.; Pforr, J.; Trump, J.; Wuyts, S.

    2017-04-01

    Galaxy interactions are thought to be one of the main triggers of active galactic nuclei (AGN), especially at high luminosities, where the accreted gas mass during the AGN lifetime is substantial. Evidence for a connection between mergers and AGN, however, remains mixed. Possible triggering mechanisms remain particularly poorly understood for luminous AGN, which are thought to require triggering by major mergers, rather than secular processes. We analyse the host galaxies of a sample of 20 optically and X-ray selected luminous AGN (log(Lbol [erg s-1]) > 45) at z ∼ 0.6 using Hubble Space Telescope Wide Field Camera 3 data in the F160W/H band. 15/20 sources have resolved host galaxies. We create a control sample of mock AGN by matching the AGN host galaxies to a control sample of non-AGN galaxies. Visual signs of disturbances are found in about 25 per cent of sources in both the AGN hosts and control galaxies. Using both visual classification and quantitative morphology measures, we show that the levels of disturbance are not enhanced when compared to a matched control sample. We find no signs that major mergers play a dominant role in triggering AGN at high luminosities, suggesting that minor mergers and secular processes dominate AGN triggering up to the highest AGN luminosities. The upper limit on the enhanced fraction of major mergers is ≤20 per cent. While major mergers might increase the incidence of luminous AGN, they are not the prevalent triggering mechanism in the population of unobscured AGN.

  1. Redshift-space distortions of galaxies, clusters, and AGN. Testing how the accuracy of growth rate measurements depends on scales and sample selections

    NASA Astrophysics Data System (ADS)

    Marulli, Federico; Veropalumbo, Alfonso; Moscardini, Lauro; Cimatti, Andrea; Dolag, Klaus

    2017-03-01

    Aims: Redshift-space clustering anisotropies caused by cosmic peculiar velocities provide a powerful probe to test the gravity theory on large scales. However, to extract unbiased physical constraints, the clustering pattern has to be modelled accurately, taking into account the effects of non-linear dynamics at small scales, and properly describing the link between the selected cosmic tracers and the underlying dark matter field. Methods: We used a large hydrodynamic simulation to investigate how the systematic error on the linear growth rate, f, caused by model uncertainties, depends on sample selections and co-moving scales. Specifically, we measured the redshift-space two-point correlation function of mock samples of galaxies, galaxy clusters and active galactic nuclei, extracted from the Magneticum simulation, in the redshift range 0.2 ≤ z ≤ 2, and adopting different sample selections. We estimated fσ8 by modelling both the monopole and the full two-dimensional anisotropic clustering, using the dispersion model. Results: We find that the systematic error on fσ8 depends significantly on the range of scales considered for the fit. If the latter is kept fixed, the error depends on both redshift and sample selection due to the scale-dependent impact of non-linearities if not properly modelled. Concurrently, we show that it is possible to achieve almost unbiased constraints on fσ8 provided that the analysis is restricted to a proper range of scales that depends non-trivially on the properties of the sample. This can have a strong impact on multiple tracer analyses, and when combining catalogues selected at different redshifts.

  2. 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.

  3. Constraining the properties of AGN host galaxies with spectral energy distribution modelling

    NASA Astrophysics Data System (ADS)

    Ciesla, L.; Charmandaris, V.; Georgakakis, A.; Bernhard, E.; Mitchell, P. D.; Buat, V.; Elbaz, D.; LeFloc'h, E.; Lacey, C. G.; Magdis, G. E.; Xilouris, M.

    2015-04-01

    realistic ages of the stellar population. The delayed SFH model provides good estimates of M∗ and SFR, with a maximum offset of 10% as well as better estimates of the age. Our analysis shows that the under-estimation of the SFR increases with fracAGN for Type-1 systems, as well as for low contributions of an intermediate AGN type, but it is quite insensitive to the emission of Type-2 AGNs up to fracAGN ~ 45%. A lack of sampling the FIR, or sub-mm domain systematically over-estimates the SFR (<20%), independent of the contribution of the AGN. Similarly, the UV emission is critical in accurately retrieving both the M∗ for Type-1 and intermediate- type AGN and the SFR of all three AGN types. We show that the presence of AGN emission introduces a scatter to the SFR-M∗ main sequence relation derived from SED-fitting, which is driven by the uncertainties on M∗. Finally, we used our mock catalogues to test the popular IR SED-fitting code DecompIR and show that fracAGN is under-estimated but that the SFR is recovered well for Type-1 and intermediate-types of AGN. The fracAGN, SFR, and LIR estimates of Type-2 AGNs are more problematic owing to a FIR emission disagreement between predicted and observed models.

  4. 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.

  5. 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.

  6. Type-II AGN population from the zCOSMOS survey

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Mignoli, M.; Zamorani, G.; Zcosmos Team

    2008-10-01

    I'll present the first results on the type-II AGN population isolated from the zCOSMOS bright sample which consists of 10k sources, purely magnitude selected at I=22.5. The selected type-II AGN sample consists of about 200 AGN, selected using the diagnostic diagrams up to redshift ~1.0. I'll present the properties of this sample (i.e. SED and morphology) and some preliminary results on the evolution of type-II AGN, as well as on the evolution of their fraction with respect to the total AGN population (Type-I + Type-II), as a function of both luminosity and redshift.

  7. 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.

  8. X-RAY ABSORPTION, NUCLEAR INFRARED EMISSION, AND DUST COVERING FACTORS OF AGNs: TESTING UNIFICATION SCHEMES

    SciTech Connect

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

    2016-03-10

    We present the distributions of the geometrical covering factors of the dusty tori (f{sub 2}) 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 10{sup 42} and 10{sup 46} erg s{sup −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 f{sub 2} 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 f{sub 2} are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f{sub 2} 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 f{sub 2} 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.

  9. 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.

  10. Analyses of the Variability Asymmetry of Kepler AGNs

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-Yang; Wang, Jun-Xian

    2015-05-01

    The high-quality light curves from the Kepler space telescope make it possible to analyze the optical variability of active galactic nuclei (AGNs) with unprecedented time resolution. Studying the asymmetry in variations could provide independent constraints on physical models for AGN variability. In this paper, we use Kepler observations of 19 sources to perform analyses of the variability asymmetry of AGNs. We apply smoothing correction to light curves to deduct their bias toward high-frequency variability asymmetry caused by long-term variations that have been poorly sampled due to the limited length of light curves. A parameter β based on structure functions is introduced to quantitively describe the asymmetry and its uncertainty is measured using extensive Monte Carlo simulations. Individual sources show no evidence of asymmetry at timescales of 1˜ 20 days and there is no general trend toward positive or negative asymmetry over the whole sample. Stacking the data from all 19 AGNs, we derive an averaged \\bar{β } of 0.00 ± 0.03 and -0.02 ± 0.04 over timescales of 1 ˜ 5 days and 5 ˜ 20 days, respectively, which are statistically consistent with zero. Quasars and Seyfert galaxies show similar asymmetry parameters. Our results indicate that short-term optical variations in AGNs are highly symmetric.

  11. 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.

  12. AGN Observations with STACEE

    NASA Astrophysics Data System (ADS)

    Bramel, D. A.; Boone, L. M.; Carson, J.; Chae, E.; Covault, C. E.; Fortin, P.; Gingrich, D. M.; Hanna, D. S.; Hinton, J. A.; Mukherjee, R.; Mueller, C.; Ong, R. A.; Ragan, K.; Scalzo, R. A.; Schuette, D. R.; Theoret, C. G.; Williams, D. A.; Wong, J.; Zweerink, J.

    2003-03-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a gamma-ray detector designed to study astrophysical sources at energies between 50 and 500 GeV. It uses 64 large, steerable mirrors at the National Solar Tower Test Facility near Albuquerque, NM, USA to collect Cherenkov light from extended air showers and concentrate it onto an array of photomultiplier tubes. The large light-collection area gives it a lower energy threshold than imaging-type Cherenkov detectors. STACEE is now fully operational, and we report here on the performance of the complete STACEE instrument, as well as preliminary results of recent observations of several AGN targets. This work was supported in part by the National Science Foundation (under Grant Numbers PHY-9983836, PHY-0070927, and PHY-0070953), the Natural Sciences and Engineering Research Council, Le Fond Quebecois de la Recherche sur la Nature et les Technologies (FQRNT), the Research Corporation, and the California Space Institute. CEC is a Cottrell Scholar of the Research Corporation.

  13. Intermittent Activity in AGN

    NASA Astrophysics Data System (ADS)

    Janiuk, A.; Czerny, B.; Siemiginowska, A.

    2004-10-01

    There is a growing evidence that the AGN activity could be intermittent. It remains an open question if this behavior is caused by changes in the fuel sup- ply to the supermassive black hole from the large distances, or rather by a processes intrinsic to the active nucleus. We consider the possibility that ac- cretion onto a supermassive black hole is controlled by an accretion disk which is subject to the hydro- gen ionization instability. This drives the observed on-off activity cycle, since periodically the accretion flow becomes inefficient and the disk goes to quies- cence. We consider effects of the MHD turbulence on the viscosity during the evolution of a standard α - disk. We perform a self-consistency check of the α de- scription of the angular momentum transfer. Hav- ing shown that the viscosity parameter is constant throughout the whole instability cycle, as implied by the strength of the MHD turbulence, we calcu- late the time evolution of the disk under the influ- ence of the ionization instability. We demonstrate that if the accretion onto a supermassive black hole proceeds through an outer standard accretion disk and inner, radiatively inefficient and advection dom- inated flow, the modelled amplitudes of disk lumi- nosity variations are sufficiently high to account for the observations. Key words: accretion disks; galaxies: active.

  14. 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..

  15. AGN jets as pion factories

    NASA Astrophysics Data System (ADS)

    Mannheim, Karl

    There has been a dramatic revolution in gamma-ray astronomy throughout the last few years. Beginning with the discovery made by the spark chamber EGRET on board the Compton Gamma Ray Observatory that AGN with jets are the most powerful quasi-steady gamma-ray sources in the Universe, air-Cerenkov telescopes have soon after succeeded in detecting gamma-rays up to TeV energies. In the last year, it has become clear that these AGN emit photons even up to 10 TeV and more. This is a strong indication for proton acceleration going on in them, since protons owing to their large mass suffer weaker energy losses than electrons and can thus reach higher energies. Nucleons escaping from the AGN jets contribute to the local flux of cosmic rays at highest energies. If AGN produce the diffuse gamma-ray background, they would also be able to produce all the cosmic rays above the ankle in the local spectrum. The majority of AGN resides at large distances, indicated by their cosmological redshifts, and can therefore not be seen through the fog of electron-positron pairs which they produce interacting with diffuse infrared radiation from the era of galaxy formation. To observe the cosmic accelerators at large redshifts, neutrino observations are required. It is important to understand the astrophysical neutrino sources in order to be able to recognize signatures of new physics, e.g. due to decaying or annihilating particles from the early phases of the Universe.

  16. 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.).

  17. 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.

  18. Hard X-ray Spectroscopy of Obscured AGN with NuSTAR

    NASA Astrophysics Data System (ADS)

    Balokovic, Mislav; Harrison, Fiona; NuSTAR Extragalactic Surveys Team

    2017-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the hard X-ray band, up to 79 keV, with unprecedented spatial resolution and sensitivity. As a part of its extragalactic program, NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT), selecting even the most obscured local AGN. I will highlight some of the results based on broadband X-ray spectroscopy of individual targets and present my work on the large representative sample of more than a hundred nearby obscured AGN, which constitutes the largest available atlas of hard X-ray spectra of obscured AGN to date. The high quality of the data allows us to probe the details of AGN structures such as the X-ray-emitting corona and the toroidal obscurer in the under-explored spectral window above 10 keV. I will present both phenomenological results important for synthesis models of the cosmic X-ray background, and a novel approach for constraining the geometry of the gas surrounding the supermassive black hole (including the accretion disk, the broad-line region, and the torus) from the hard X-ray band. Finally, I will discuss how what we learned from this survey of local AGN relates to deeper high-redshift X-ray surveys and AGN structure probes at other wavelengths.

  19. A Herschel Study of 24 μμm-Selected AGNs and Their Host Galaxies

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    We present a sample of 290 24 μm-selected active galactic nuclei (AGNs) mostly at z ˜ 0.3-2.5, within 5.2 {{deg}}2 distributed as 25\\prime × 25\\prime fields around each of 30 galaxy clusters in the Local Cluster Substructure Survey. The sample is nearly complete to 1 mJy at 24 μm, and has a rich multiwavelength set of ancillary data; 162 are detected by Herschel. We use spectral templates for AGNs, stellar populations, and infrared (IR) emission by star-forming galaxies to decompose the spectral energy distributions (SEDs) of these AGNs and their host galaxies, and estimate their star formation rates, AGN luminosities, and host galaxy stellar masses. The set of templates is relatively simple: a standard Type-1 quasar template; another for the photospheric output of the stellar population; and a far-infrared star-forming template. For the Type-2 AGN SEDs, we substitute templates including internal obscuration, and some Type-1 objects require a warm component (T≳ 50 K). The individually Herschel-detected Type-1 AGNs and a subset of 17 Type-2 AGNs typically have luminosities \\gt {10}45 {ergs} {{{s}}}-1, and supermassive black holes of ˜ 3× {10}8 {M}⊙ emitting at ˜10% of the Eddington rate. We find them in about twice the numbers of AGNs identified in SDSS data in the same fields, i.e., they represent typical high-luminosity AGNs, not an IR-selected minority. These AGNs and their host galaxies are studied further in an accompanying paper.

  20. The Emission Line AGN Census: Biases of Line Ratio Selection, and Uniform Black Hole Accretion Regardless of Galaxy Mass

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; Zeimann, Gregory; Juneau, Stephanie; Sun, Mouyuan; Luck, Cuyler

    2015-01-01

    Optical emission line ratios offer a powerful tool to reveal accretion onto supermassive black holes, with the ability to find both unobscured and obscured active galactic nuclei (AGNs) in extraordinarily large galaxy samples (like the SDSS). I will demonstrate, however, that classic line ratio selection techniques significantly underestimate the AGN fraction by a factor of >10 in low-mass and star-forming galaxies. Previous conclusions that AGNs require massive green-valley hosts are purely a result of this "star formation dilution" bias. Careful treatment of the biases reveals that AGN accretion is uniform across star-forming galaxies of any stellar mass, similar to the results of bias-corrected X-ray AGN studies. This has dramatic implications for AGN feedback in dwarf galaxies and constraints on the black hole seed population.

  1. 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.

  2. Angular Broadening of Intraday Variable AGNs II. Interstellar and Intergalactic Scattering

    DTIC Science & Technology

    2008-01-01

    scattering from any possible intergalactic contribution, we have searched for pulsars within 1 of theAGNs in our sample.We find no pulsars this close to any...of our sources.Given the relatively low density of pulsars on the sky, a significantly larger sample of AGNs would be required in order to make such a...in pulsar dynamic spectra (Hill et al. 2005). We can also use the difference between the scintillating and nonscintillating sources to set

  3. PRIMUS: The Dependence of AGN Accretion on Host Stellar Mass and Color

    NASA Astrophysics Data System (ADS)

    Aird, James; Coil, Alison L.; Moustakas, John; Blanton, Michael R.; Burles, Scott M.; Cool, Richard J.; Eisenstein, Daniel J.; Smith, M. Stephen M.; Wong, Kenneth C.; Zhu, Guangtun

    2012-02-01

    We present evidence that the incidence of active galactic nuclei (AGNs) and the distribution of their accretion rates do not depend on the stellar masses of their host galaxies, contrary to previous studies. We use hard (2-10 keV) X-ray data from three extragalactic fields (XMM-LSS, COSMOS, and ELAIS-S1) with redshifts from the Prism Multi-object Survey to identify 242 AGNs with L 2-10 keV = 1042-44 erg s-1 within a parent sample of ~25,000 galaxies at 0.2 < z < 1.0 over ~3.4 deg2 and to i ~ 23. We find that although the fraction of galaxies hosting an AGN at fixed X-ray luminosity rises strongly with stellar mass, the distribution of X-ray luminosities is independent of mass. Furthermore, we show that the probability that a galaxy will host an AGN can be defined by a universal Eddington ratio distribution that is independent of the host galaxy stellar mass and has a power-law shape with slope -0.65. These results demonstrate that AGNs are prevalent at all stellar masses in the range 9.5 and that the same physical processes regulate AGN activity in all galaxies in this stellar mass range. While a higher AGN fraction may be observed in massive galaxies, this is a selection effect related to the underlying Eddington ratio distribution. We also find that the AGN fraction drops rapidly between z ~ 1 and the present day and is moderately enhanced (factor ~2) in galaxies with blue or green optical colors. Consequently, while AGN activity and star formation appear to be globally correlated, we do not find evidence that the presence of an AGN is related to the quenching of star formation or the color transformation of galaxies.

  4. 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.

  5. The jet-disc connection in AGN

    NASA Astrophysics Data System (ADS)

    Sbarrato, T.; Padovani, P.; Ghisellini, G.

    2014-11-01

    We present our latest results on the connection between accretion rate and relativistic jet power in active galactic nuclei (AGN), by using a large sample which includes mostly blazars, but contains also some radio galaxies. The jet power can be traced by γ-ray luminosity in the case of blazars, and radio luminosity for both classes. The accretion-disc luminosity is instead traced by the broad emission lines. Among blazars, we find a correlation between broad line emission and the γ-ray or radio luminosities, suggesting a direct tight connection between jet power and accretion rate. We confirm that the observational differences between blazar subclasses reflect differences in the accretion regime, but with blazars only we cannot properly access the low-accretion regime. By introducing radio galaxies, we succeed in observing the fingerprint of the transition between radiatively efficient and inefficient accretion discs in the jetted AGN family. The transition occurs at the standard critical value Ld/LEdd ˜ 10-2 and it appears smooth. Below this value, the ionizing luminosity emitted by the accretion structure drops significantly.

  6. 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.

  7. X-ray selected AGN in groups at redshifts z ~ 1

    NASA Astrophysics Data System (ADS)

    Georgakakis, A.; Gerke, Brian F.; Nandra, K.; Laird, E. S.; Coil, A. L.; Cooper, M. C.; Newman, J. A.

    2008-11-01

    We explore the role of the group environment in the evolution of active galactic nuclei (AGN) at the redshift interval 0.7 < z < 1.4, by combining deep Chandra observations with extensive optical spectroscopy from the All-wavelength Extended Groth strip International Survey (AEGIS). The sample consists of 3902 optical sources and 71 X-ray AGN. Compared to the overall optically selected galaxy population, X-ray AGN are more frequently found in groups at the 99 per cent confidence level. This is partly because AGN are hosted by red luminous galaxies, which are known to reside, on average, in dense environments. Relative to these sources, the excess of X-ray AGN in groups is significant at the 91 per cent level only. Restricting the sample to 0.7 < z < 0.9 and MB < -20mag in order to control systematics, we find that X-ray AGN represent (4.7 +/- 1.6) and (4.5 +/- 1.0) per cent of the optical galaxy population in groups and in the field, respectively. These numbers are consistent with the AGN fraction in low-redshift clusters, groups and the field. The above results, although affected by small number statistics, suggest that X-ray AGN are spread over a range of environments, from groups to the field, once the properties of their hosts (e.g. colour, luminosity) are accounted for. There is also tentative evidence, significant at the 98 per cent level, that the field produces more X-ray luminous AGN compared to groups, extending similar results at low redshift to z ~ 1. This trend may be because of either cold gas availability or the nature of the interactions occurring in the denser group environment (i.e. prolonged tidal encounters).

  8. 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

  9. Non-thermal AGN models

    SciTech Connect

    Band, D.L.

    1986-12-01

    The infrared, optical and x-ray continua from radio quiet active galactic nuclei (AGN) are explained by a compact non-thermal source surrounding a thermal ultraviolet emitter, presumably the accretion disk around a supermassive black hole. The ultraviolet source is observed as the ''big blue bump.'' The flat (..cap alpha.. approx. = .7) hard x-ray spectrum results from the scattering of thermal ultraviolet photons by the flat, low energy end of an electron distribution ''broken'' by Compton losses; the infrared through soft x-ray continuum is the synchrotron radiation of the steep, high energy end of the electron distribution. Quantitative fits to specific AGN result in models which satisfy the variability constraints but require electron (re)acceleration throughout the source. 11 refs., 1 fig.

  10. 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.

  11. X-Ray Selected AGN in A Merging Cluster

    NASA Astrophysics Data System (ADS)

    Taylor, Joanna M.; Norman, D.; Soechting, I.; Coldwell, G.

    2012-01-01

    We investigate the X-ray AGN population and evolution in the merging galaxy cluster DLSCL J0522.2-4820 discovered via weak gravitational lensing shear from the Deep Lens Survey (DLS). Since weak lensing shear is dependent only on mass, it does not introduce the biases that typical cluster selection methods do. This cluster is of particular interest due to both its extended multiple X-ray emission peaks and the large number of X-ray point sources identified in the field. We measured the redshifts of X-ray AGN as well as cluster galaxies in order to investigate the 3-dimensional distribution and possible clustering of AGN in galaxy clusters. Of the 125 objects in our sample, 54 are galaxies in the cluster; the cluster redshift is determined to be z=0.2997±0.0096. This agrees well with a previous value of z=0.296±0.001. We identified several broad line AGN at high redshift including a quasar pair at redshift z=1.8. Currently, we have found no X-ray point sources to be within the cluster. This project was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program and the Department of Defense ASSURE program through Scientific Program Order No. 13 (AST-0754223) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

  12. 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.

  13. Unveiling the physics of AGN through X-ray variability

    NASA Astrophysics Data System (ADS)

    Hernández-García, L.; González-Martín, O.; Masegosa, J.; Márquez, I.

    2017-03-01

    Although variability is a general property characterizing active galactic nuclei (AGN), it is not well established whether the changes occur in the same way in every nuclei. The main purpose of this work is to study the X-ray variability pattern(s) in AGN selected at optical wavelengths in a large sample, including low ionization nuclear emission line regions (LINERs) and type 1.8, 1.9, and 2 Seyferts, using the public archives in Chandra and/or XMM–Newton. Spectra of the same source gathered at different epochs were simultaneously fitted to study long term variations; the variability patterns were studied allowing different parameters to vary during the spectral fit. Whenever possible, short term variations from the analysis of the light curves and long term UV flux variability were studied. Variations at X-rays in timescales of months/years are very common in all AGN families but short term variations are only found in type 1.8 and 1.9 Seyferts. The main driver of the long term X-ray variations seems to be related to changes in the nuclear power. Other variability patterns cannot be discarded in a few cases. We discuss the geometry and physics of AGN through the X-ray variability analysis.

  14. The Importance of Winds for AGN Feedback

    NASA Astrophysics Data System (ADS)

    Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Fischer, T. C.; Gagne, J.

    2014-01-01

    Active galactic nuclei (AGN) are fed by accretion of matter onto supermassive black holes (SMBHs), generating huge amounts of radiation from very small volumes. AGN also provide feedback to their environments via mass outflows of ionized gas, which could play a critical role in the formation of large-scale structure in the early Universe, chemical enrichment of the intergalactic medium, and self-regulation of SMBH and galactic bulge growth. We provide an update on our research on the winds in nearby moderate-luminosity AGN, In particular, we concentrate on winds that occur on relatively large scales (hundreds of parsecs) that are revealed through spatially resolved HST spectra of emission-line gas in the narrow line regions (NLRs) of nearby AGN. We discuss the techniques for measuring the mass outflow rates and kinetic luminosities of these AGN winds and gauge their importance for providing significant AGN feedback.

  15. 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.

  16. The ``entropy floor'' is porous - remarks on the coexistence of star formation and kinetic AGN feedback

    NASA Astrophysics Data System (ADS)

    Tremblay, Grant R.

    2014-07-01

    We discuss the morphology of star forming clouds and filaments in the central (<~ 50 kpc) regions of 16 low redshift (z<0.3) cool core brightest cluster galaxies (BCGs). The sample spans decades-wide ranges of X-ray mass deposition and star formation rates as well as active galactic nucleus (AGN) mechanical power, encompassing both high and low extremes of the supposed intracluster medium (ICM) cooling and AGN heating feedback cycle. Amid evidence that the gas fueling both star formation and AGN activity has condensed from the hot atmosphere, we present new and archival Hubble Space Telescope (HST) images of far ultraviolet (FUV) continuum emission directly associated with young stars, acting as a calorimeter for the degree to which the suppression of star formation by AGN mechanical feedback may be spatially or temporally inefficient. We discuss evidence for temporal and possibly cyclical variation in star formation rate, wherein elevated cooling episodes are permitted when AGN feedback is in a low-power state, and vice-versa. Several sources exhibit strong morphological evidence that low levels of star formation can survive and may indeed be triggered by the passage of a propagating radio source. We conclude by discussing the apparent coexistence of feedback and star formation. If AGN mechanical power does establish an ``entropy floor'', this floor must be porous, or raise and lower as the AGN varies in power.

  17. Starburst and AGN Indicators in Optically Faint X-ray Sources in the Cosmic Evolution Survey

    NASA Astrophysics Data System (ADS)

    Robins, Derek; Elvis, M.; Civano, F.

    2011-01-01

    A sample of 55 faint, X-ray selected objects were chosen for analysis from the COSMOS survey with high quality Keck DEIMOS data. The average redshift of the sample was 1.36, consistent with the average redshift of type 1 AGN in COSMOS of 1.4. Emission lines, NeV - an indicator of AGN luminosity - and OII - an indicator of star formation rate, were measured for a subset of 34 objects. Line properties for these objects were measured. The combination of the two lines is evidence for significant star formation in these obscured AGN. Differences between OII and NeV redshifts were measured carefully. Significant differences between OII and NeV redshifts were found in 10-14 objects, implying OII outflows. The results are consistent with current models of galaxy evolution that invoke an interplay between AGN activity and star formation.

  18. New insights into AGN coronae

    NASA Astrophysics Data System (ADS)

    Lohfink, Anne; Fabian, Andrew C.; Malzac, Julien; Belmont, Renaud; Buisson, Douglas

    2016-04-01

    Active galactic nuclei (AGN) are some of the most energetic sources of radiation in the Universe. The conversion of gravitational energy into radiation is thought to take place in an accretion disk/corona system just outside the black hole. In this system thermal, UV/optical photons from the accretion disk are upscattered in a corona of hot electrons situated above the accretion disk producing X-rays. The nature of this Comptonizing corona remains a key open question in AGN physics. The NuSTAR satellite provides the opportunity to study the Comptonization spectrum produced by the corona in great detail. In our talk we will show some key results from these new studies of the Comptonization spectrum. We explore how, together with our growing knowledge of coronal sizes, we are able to draw first conclusions about the physics taking place in the corona. We find evidence for coronae to be hot and radiatively compact, putting them close to the boundary of the region in the compactness-temperature diagram which is forbidden due to runaway pair production. This suggests that pair production and annihilation are essential ingredients in the coronae of AGN and that they control the coronal temperature and shape of the observed spectra.

  19. Detecting Dual AGN at High Redshift

    NASA Astrophysics Data System (ADS)

    Barrows, Robert S.

    2012-01-01

    The existence of supermassive black holes (SMBHs) in most, if not all, galaxies, along with observations of galaxy mergers, suggests that pairs of SMBHs should exist for some time in the merger remnant. Observational evidence for these systems at kpc-scale separations (i.e. dual AGN) has dramatically increased recently through a combination of spectral and morphological selections. I discuss observations of CXOXBJ142607.6+353351 (CXOJ1426+35), a candidate dual AGN at z=1.175, and put its properties, including significant obscuration, within the context of other candidate/confirmed dual AGN at lower redshifts. Though dual AGN are expected to be more common at higher redshifts, they are more difficult to detect. Furthermore, adding to the difficulties of detection are a number of other physical mechanisms which can mimic the spectroscopic signature of two Type 2 AGN. In particular, I will discuss the possibility of strong outflows from an AGN. These outflow phenomena can be an important feedback mechanism in galaxies and are apparently common in AGN, making them a viable alternative to the dual AGN scenario. Based on our candidate's luminosity and emission line intensities, we find that an outflow is a possibility. If this is the case, such an outflow would be especially strong and has implications for AGN feedback in galaxies. However, the dual AGN scenario cannot be ruled out, and at z=1.175, the two putative AGN could potentially be resolved with Chandra. Other candidate dual AGN at similar redshifts and with significant obscuration could also be confirmed this way. This research was sponsored by the Strategic University Research Partnership Program, the National Aeronautics and Space Administration and the Arkansas NASA EPSCoR program.

  20. 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.

  1. The Universal Unification Model of AGN

    NASA Astrophysics Data System (ADS)

    Vilkoviskij, E. Y.

    1998-12-01

    It is shown, that the model calculations of the absorption line profiles are possible in the framework of a common model both for BAL QSOs and the Seyfert galaxies with BAL. We suppose that in both cases the BAL-clouds move in the space between two conic surface, starting in the internal surface of the absorbing torus. We argue that the common nature of the intrinsic line absorption in these objects can be explained in an universal unified AGN model, where BAL AGNs are objects intermediate between AGN1 and AGN2

  2. The host galaxies of ultra hard X-ray selected AGN

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.

    One of the great mysteries surrounding active galactic nuclei (AGN) is their triggering mechanism. Since the discovery that almost all massive galaxies host nuclear supermassive black holes, it has become clear that a trigger mechanism is required to 'turn on' and continue to fuel the central black hole. While it is established that accretion processes are responsible for the energy emitted, the source of the accreting material is still controversial. Furthermore, the energy input from phases of black hole growth is thought to be a key regulator in the formation of galaxies and the establishment of various scaling relations. Theorists often invoke galaxy mergers as the violent mechanism to drive gas into the central regions and ignite luminous quasars, but among more common moderate luminosity AGN, there has been great controversy whether secular processes or mergers dominate AGN fueling. A survey in the ultra hard X-ray band (14--195 keV) is an important new way to answer the fundamental question of AGN fueling. This method is independent of selection effects such as dust extinction and obscuration that plague surveys at other wavelengths because of the ability of the primary continuum to easily pass through large columns of obscuring gas and dust (<10 24 cm-2). In this PhD, we have assembled the largest sample of ultra hard X-ray selected AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift BAT sample. We find that these AGN show much higher rates of both mergers and massive spirals suggesting both mergers and accretion of cold gas in late type systems are important in AGN fueling. We also find that the most common AGN survey technique, optical line diagnostics, is heavily biased against finding AGN in mergers or spirals. Finally, in agreement with the merger driven AGN link, we find that dual AGN systems may be more common than current observation suggest since some of them are only detected using high

  3. 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.

  4. 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.

  5. The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. I. Very Large Array Detections of Dual AGNs and AGN Outflows

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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. Based on observations at the NRAO Karl G. Jansky VLA (program 12A-103).

  6. 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.

  7. 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.

  8. Active galactic nuclei from He II: a more complete census of AGN in SDSS galaxies yields a new population of low-luminosity AGN in highly star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Bär, Rudolf E.; Weigel, Anna K.; Sartori, Lia F.; Oh, Kyuseok; Koss, Michael; Schawinski, Kevin

    2017-04-01

    In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the He II λ4685 emission line diagnostic diagram by Shirazi & Brinchmann (2012) in addition to the standard methods based on other optical emission lines. The He II-based diagnostics is more sensitive to AGN ionization in the presence of strong star formation than conventional line diagnostics. We survey a magnitude-limited sample of 63 915 galaxies from the Sloan Digital Sky Survey Data Release 7 at 0.02 < z < 0.05 and use both the conventional BPT emission line diagnostic diagrams, as well as the He II diagram to identify AGN. In this sample, 1075 galaxies are selected as AGN using the BPT diagram, while additional 234 galaxies are identified as AGN using the He II diagnostic diagram, representing a 22 per cent increase of AGN in the parent galaxy sample. We explore the host galaxy properties of these new He II-selected AGN candidates and find that they are most common in star-forming galaxies on the blue cloud and on the main sequence where ionization from star formation is most likely to mask AGN emission in the BPT lines. We note in particular a high He II AGN fraction in galaxies above the high-mass end of the main sequence where quenching is expected to occur. We use archival Chandra observations to confirm the AGN nature of candidates selected through He II-based diagnostic. Finally, we discuss how this technique can help inform galaxy/black hole coevolution scenarios.

  9. Active Galactic Nuclei from He II: a more complete census of AGN in SDSS galaxies yields a new population of low-luminosity AGN in highly star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Baer, Rudolf E.; Weigel, Anna; Sartori, Lia F.; Oh, Kyuseok; Koss, Michael; Schawinski, Kevin

    2017-01-01

    In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the He II emission line diagnostic diagram by Shirazi & Brinchmann (2012) in addition to the standard methods based on other optical emission lines. The He II based diagnostics is more sensitive to AGN ionization in the presence of strong star formation than conventional line diagnostics. We survey a magnitude-limited sample of 81,192 galaxies from the Sloan Digital Sky Survey Data Release 7 at 0.02 < z < 0.05 and apply both the conventional BPT emission line diagnostic diagrams, as well as the He II diagram to identify AGN. In this sample, 1,075 galaxies are selected as AGN using the BPT diagram, while an additional 234 galaxies are identified as AGN using the He II diagnostic, representing a 22% increase of AGN in the parent galaxy sample. We use archival Chandra observations to confirm the AGN nature of candidates selected through He II based diagnostic. Finally, we explore the host galaxy properties of these new He II selected AGN candidates and find that they are most common in star-forming galaxies on the blue cloud and on the main sequence where ionization from star-formation is most likely to mask AGN emission in the BPT lines. We note in particular a high He II AGN fraction in galaxies above the high-mass end of the main sequence where quenching is expected to occur. We discuss how this technique can help inform galaxy/black hole co-evolution scenarios.

  10. 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.

  11. 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

  12. 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.

  13. Star formation in AGNs at the hundred parsec scale using MIR high-resolution images

    NASA Astrophysics Data System (ADS)

    Ruschel-Dutra, Daniel; Rodríguez Espinosa, José Miguel; González Martín, Omaira; Pastoriza, Miriani; Riffel, Rogério

    2017-04-01

    It has been well established in the past decades that the central black hole masses of galaxies correlate with dynamical properties of their harbouring bulges. This notion begs the question of whether there are causal connections between the active galactic nucleus (AGN) and its immediate vicinity in the host galaxy. In this paper, we analyse the presence of circumnuclear star formation in a sample of 15 AGN using mid-infrared observations. The data consist of a set of 11.3 μm polycyclic aromatic hydrocarbon emission and reference continuum images, taken with ground-based telescopes, with sub-arcsecond resolution. By comparing our star formation estimates with AGN accretion rates, derived from X-ray luminosities, we investigate the validity of theoretical predictions for the AGN-starburst connection. Our main results are: (i) circumnuclear star formation is found, at distances as low as tens of parsecs from the nucleus, in nearly half of our sample (7/15); (ii) star formation luminosities are correlated with the bolometric luminosity of the AGN (LAGN) only for objects with LAGN ≥ 1042 erg s-1; (iii) low-luminosity AGNs (LAGN < 1042 erg s-1) seem to have starburst luminosities far greater than their bolometric luminosities.

  14. 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.

  15. Results from the NuSTAR Survey of Swift/BAT AGN

    NASA Astrophysics Data System (ADS)

    Balokovic, Mislav; Harrison, Fiona

    2015-08-01

    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). We present results based on 15-25 ks observations of ~150 Swift/BAT AGN surveyed in the first 2.5 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. 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 (spectral index, high-energy cut-off, absorption column, reflection strength, iron line equivalent width) in a well-defined population of nearby AGN. We find that approximately 70% of obscured AGN spectra can be well modeled in terms of simple models used in the literature, while the rest requires careful consideration of more advanced models. We will discuss the implications for the local AGN population, the effects on interpretation of high-redshift AGN observations, and the limitations of the current results.

  16. Differences in Halo-scale Environments between Type 1 and Type 2 AGNs at Low Redshift

    NASA Astrophysics Data System (ADS)

    Jiang, Ning; Wang, Huiyuan; Mo, Houjun; Dong, Xiao-Bo; Wang, Tinggui; Zhou, Hongyan

    2016-12-01

    Using low-redshift (z\\lt 0.09) samples of active galactic nuclei (AGNs), normal galaxies and groups of galaxies selected from the Sloan Digital Sky Survey, we study the environments of Type 1 and Type 2 AGNs, both on small and large scales. Comparisons are made for galaxy samples matched in redshift, r-band luminosity, [O iii] luminosity, and also the position in groups (central or satellite). We find that Type 2 AGNs and normal galaxies reside in similar environments. Type 1 and Type 2 AGNs have similar clustering properties on large scales (≳ 1 {h}-1 {Mpc}), but at scales smaller than 100 {h}-1 {kpc}, Type 2s have significantly more neighbors than Type 1s (3.09 ± 0.69 times more for central AGNs at ≲ 30 {h}-1 {kpc}). These results suggest that Type 1 and Type 2 AGNs are hosted by halos of similar masses, as can also be seen directly from the mass distributions of their host groups (˜ {10}12 {h}-1 {M}⊙ for centrals and ˜ {10}13 {h}-1 {M}⊙ for satellites). Type 2s have significantly more satellites around them, and the distribution of their satellites is also more centrally concentrated. The host galaxies of both types of AGNs have similar optical properties, but their infrared colors are significantly different. Our results suggest that the simple unified model based solely on torus orientation is not sufficient, but that galaxy interactions in dark matter halos must have played an important role in the formation of the dust structure, which obscures AGNs.

  17. 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.

  18. 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

    DOE PAGES

    Hlavacek-Larrondo, J.; McDonald, M.; Benson, B. 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). Here, we report on a survey for X-ray cavities in 83 massive, high-redshift (more » $$0.4\\lt z\\lt 1.2$$) 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). Furthermore, 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 108 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. Though our 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.« less

  19. 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

    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). Here, 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). Furthermore, 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 108 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. Though our 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.

  20. 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

    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 108 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.

  1. 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

  2. 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.

  3. Mid-Infrared Spectroscopy of the Brightest Type 2 AGN in the SDSS

    NASA Astrophysics Data System (ADS)

    Heckman, Timothy; Armus, Lee; Martins, Lucimara; Tremonti, Christy

    2006-05-01

    We propose to use the IRS on Spitzer to observe a complete and well-defined sample of the 20 brightest Type 2 (obscured) Active Galactic Nuclei (AGN) in the Sloan Digital Sky Survey (SDSS). They are selected from a sample of over 100,000 SDSS AGN on the basis of the flux in the [OIII]5007 emission-line. The full SDSS sample has been used to study the properties of local AGN and their host galaxies with unmatched statistical precision. The results imply that there is on-going co-evolution of black holes and galaxy bulges in the present universe (albeit at lower mass scales than in the past). Given the sensitivity of optical observations to even modest amounts of dust extinction, it is imperative to determine whether mid-IR and optical observations of these objects are consistent. The general goal of the proposal is to produce a set of high-quality mid-IR spectra for a complete sample of the brightest SDSS Type 2 AGN. The specific goals are: 1) To compare measurements of the AGN luminosity derived from the high-ionization mid-IR emission-lines to those derived from similar optical emission-lines. 2) To compare estimates of the relative energetic significance of black hole accretion and star formation in AGN host galaxies derived from optical data to those derived from mid-IR spectroscopy. These two goals address the following two questions: 1) How well can the luminosity of Type 2 SDSS AGN be estimated from optical spectra alone? 2) Can the coupled growth of black holes and galaxy bulges in the low-z universe be adequately quantified from optical data alone? Using the IRS to observe a complete sub-set of the 100,000 Type 2 SDSS AGN is essential to understand the degree to which the SDSS data provide a fair picture of the low-redshift AGN phenomenon. These data will beautifully complement existing IRS surveys of IR-selected AGN.

  4. How accurate is [CII] tracing star formation in nearby luminous AGN?

    NASA Astrophysics Data System (ADS)

    Husemann, Bernd

    2015-10-01

    We propose [CII] line mapping with FIFI-LS for a sample of 8 nearby luminous AGN as part of our Close AGN Reference Survey (CARS). Our aim is to create a spatially-resolved multi-wavelength dataset to understand whether and how AGN can control star formation in their hosts. We already obtained wide-field optical IFU spectroscopy with MUSE to disentangle emission from HII regions and photoionized gas by the AGN across the galaxies. Currently, there is a high pressure to understand the impact of AGN especially at the peak of cosmic star formation beyond z>2 where measuring the SF is diffcult. The [CII] line at 158microns has become an important diagnostic for SF in high-redshift galaxies with the advent of ALMA. However, the line can be excited by various mechanisms in a multi-phase ISM. In particular the hard radiation field of AGN is a major concern which can only be quantified in nearby galaxies. FIFI-LS aboard SOFIA is currently the only way to perform follow-up observations of FIR emission lines. By uniquily combining MUSE and FIFI-LS we will be able to 1. test if the empirical [CII]-SFR scaling relation hold for luminous nearby AGN, 2. quantifiy any deviation as a function of AGN luminosity, 3. test if the [CII] line kinematics are strongly affected by outflows or trace solely the kinematics of the cold gas disc. Those observations for nearby galaxies with FIFI-LS are crucially needed to establish a reference frame for interpreting high-redshift observation with ALMA at similar physical resolution.

  5. AGNfitter: A Bayesian MCMC Approach to Fitting Spectral Energy Distributions of AGNs

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    We present AGNfitter, a publicly available open-source algorithm implementing a fully Bayesian Markov Chain Monte Carlo method to fit the spectral energy distributions (SEDs) of active galactic nuclei (AGNs) from the sub-millimeter to the UV, allowing one to robustly disentangle the physical processes responsible for their emission. AGNfitter makes use of a large library of theoretical, empirical, and semi-empirical models to characterize both the nuclear and host galaxy emission simultaneously. The model consists of four physical emission components: an accretion disk, a torus of AGN heated dust, stellar populations, and cold dust in star-forming regions. AGNfitter determines the posterior distributions of numerous parameters that govern the physics of AGNs with a fully Bayesian treatment of errors and parameter degeneracies, allowing one to infer integrated luminosities, dust attenuation parameters, stellar masses, and star-formation rates. We tested AGNfitter’s performance on real data by fitting the SEDs of a sample of 714 X-ray selected AGNs from the XMM-COSMOS survey, spectroscopically classified as Type1 (unobscured) and Type2 (obscured) AGNs by their optical-UV emission lines. We find that two independent model parameters, namely the reddening of the accretion disk and the column density of the dusty torus, are good proxies for AGN obscuration, allowing us to develop a strategy for classifying AGNs as Type1 or Type2, based solely on an SED-fitting analysis. Our classification scheme is in excellent agreement with the spectroscopic classification, giving a completeness fraction of ˜ 86 % and ˜ 70 % , and an efficiency of ˜ 80 % and ˜ 77 % , for Type1 and Type2 AGNs, respectively.

  6. Constraining the UV emissivity of AGN throughout cosmic time via X-ray surveys

    NASA Astrophysics Data System (ADS)

    Ricci, Federica; Marchesi, Stefano; Shankar, Francesco; La Franca, Fabio; Civano, Francesca

    2017-02-01

    The cosmological process of hydrogen (H I) reionization in the intergalactic medium is thought to be driven by UV photons emitted by star-forming galaxies and ionizing active galactic nuclei (AGN). The contribution of quasars (QSOs) to H I reionization at z > 4 has been traditionally believed to be quite modest. However, this view has been recently challenged by new estimates of a higher faint-end UV luminosity function (LF). To set firmer constraints on the emissivity of AGN at z < 6, we here make use of complete X-ray-selected samples including deep Chandra and new Cosmic Evolution Survey data, capable to efficiently measure the 1 Ryd comoving AGN emissivity up to z ∼ 5-6 and down to 5 mag fainter than probed by current optical surveys, without any luminosity extrapolation. We find good agreement between the logNH ≲ 21-22 cm-2 X-ray LF and the optically selected QSO LF at all redshifts for M1450 ≤ -23. The full range of the logNH ≲ 21-22 cm-2 LF (M1450 ≤ -17) was then used to quantify the contribution of AGN to the critical value of photon budget needed to keep the Universe ionized. We find that the contribution of ionizing AGN at z = 6 is as small as 1-7 per cent, and very unlikely to be greater than 30 per cent, thus excluding an AGN-dominated reionization scenario.

  7. Dusting off the star formation history of AGN hosts with SHARDS

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio

    2015-03-01

    Recent works show that the restframe colours of X-ray selected AGN host galaxies at z~1 are no different from those of inactive galaxies once stellar mass selection effects are taken into account. However, there is a clear deficit of AGN among quiescent galaxies, and the average star formation rates of AGN hosts are comparable or higher than those of inactive star-forming galaxies. These apparently contradictory findings could be a consequence of higher extinction in star-forming AGN hosts compensating for their younger stellar populations in observed colours. In this talk I will present a new method of extinction correction that breaks the degeneracy with stellar age and metallicity by comparing the restframe U-V colour with measurements of the Dn(4000) index on intermediate band photospectra from SHARDS. I'll show that the distribution of extinction corrected U-V colours and Dn(4000) for AGN hosts at z<1 is significantly different from that of comparison samples of inactive galaxies, with a clear deficit of AGN in intrinsic red galaxies and a higher prevalence among those with intermediate age stellar populations.

  8. Role of feedback in AGN-host coevolution: A study from partially obscured active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2015-05-01

    Partially obscured AGNs within a redshift range z = 0.011 ∼ 0.256 are used to re-study the role of feedback in the AGN-host coevolution issue in terms of their [OIII] λ 5007 emission line profile. The spectra of these objects enable us to determine the AGN's accretion properties directly from their broad H α emission. This is essential for getting rid of the "circular reasoning" in our previous study of narrow emission-line galaxies, in which the [OIII] emission line was used not only as a proxy of AGN's bolometric luminosity, but also as a diagnostic of outflow. In addition, the measurement of Dn (4000) index is improved by removing an underlying AGN's continuum according to the corresponding broad H α emission. With these improvements, we confirm and reinforce the correlation between L /LEdd and stellar population age. More important is that this correlation is found to be related to both [OIII] line blue asymmetry and bulk blueshift velocity, which suggests a linkage between SMBH growth and host star formation through the feedback process. The current sample of partially obscured AGNs shows that the composite galaxies have younger host stellar population, higher Eddington ratio, less significant [OIII] blue wing and smaller bulk [OIII] line shift than do the Seyfert galaxies.

  9. The impact of AGN feedback and baryonic cooling on galaxy clusters as gravitational lenses

    NASA Astrophysics Data System (ADS)

    Mead, James M. G.; King, Lindsay J.; Sijacki, Debora; Leonard, Adrienne; Puchwein, Ewald; McCarthy, Ian G.

    2010-07-01

    We investigate the impact of active galactic nucleus (AGN) feedback on the gravitational lensing properties of a sample of galaxy clusters with masses in the range 1014-1015 Msolar, using state-of-the-art simulations. Adopting a ray-tracing algorithm, we compute the cross-section of giant arcs from clusters simulated with dark matter (DM) only physics, DM plus gas with cooling and star formation (CSF) and DM plus gas with cooling, star formation and AGN feedback (CSFBH). Once AGN feedback is included, baryonic physics boosts the strong-lensing cross-section by much less than previously estimated using clusters simulated with only CSF. For a cluster with a virial mass of 7.4 × 1014 Msolar, inclusion of baryonic physics without feedback can boost the cross-section by as much as a factor of 3, in agreement with previous studies, whereas once AGN feedback is included this maximal figure falls to a factor of 2 at most. Typically, clusters simulated with DM and CSFBH physics have similar cross-sections for the production of giant arcs. We also investigate how baryonic physics affects the weak-lensing properties of the simulated clusters by fitting NFW profiles to synthetic weak-lensing data sets using a Markov Chain Monte Carlo approach, and by performing non-parametric mass reconstructions. Without the inclusion of AGN feedback, measured concentration parameters can be much larger than those obtained with AGN feedback, which are similar to the DM-only case.

  10. AGN Accretion Physics: Insights from K2

    NASA Astrophysics Data System (ADS)

    Vogeley, Michael

    We propose to use Kepler K2 mission observations of 1800 supermassive black holes at the centers of galaxies (Active Galactic Nuclei; AGN) to test models for accretion physics, to study the relationship between variability and other AGN properties such as accretion rate, and to guide methods for detecting and classifying AGN in future time-domain surveys. AGN exhibit optical brightness fluctuations on timescales from below an hour up to many years. These fluctuations are determined by the physics of accretion of matter onto black holes from their galactic environment. By observing variability on timescales down to below an hour, Kepler probes the accretion region on length scales that are too small to be directly imaged using conventional telescopes. These data allow us to test competing models for accretion physics that make different predictions for the statistics of variability. Our previous work provides strong evidence that models of AGN variability that work on long timescale data are not adequate to describe the full range of fluctuation timescales probed by Kepler. We will analyze the light curves of 1800 AGN that have been monitored by Kepler during recent and ongoing K2 campaigns. These objects span a large range of luminosity and AGN type, thus allowing study of the relationship between variability and other physical properties. We will characterize the statistics of AGN variability using state-of-the-art methods of time series analysis that are appropriate for quantifying the stochastic behavior of AGN. This analysis builds on our previous work in which we developed and tested new analysis software that extracts the full information content of these light curves and will enable several key outcomes: (1) Measurement of the relationship between types of AGN and their variability. (2) Tests for dependence of variability on accretion rate. (3) Investigation of changes in variability behavior that point to changes in the mode of accretion. (4) Correlations

  11. Do some AGN lack X-ray emission?

    NASA Astrophysics Data System (ADS)

    Simmonds, C.; Bauer, F. E.; Thuan, T. X.; Izotov, Y. I.; Stern, D.; Harrison, F. A.

    2016-12-01

    Context. Intermediate-mass black holes (IMBHs) are thought to be the seeds of early supermassive black holes (SMBHs). While ≳100 IMBH and small SMBH candidates have been identified in recent years, few have been robustly confirmed to date, leaving their number density in considerable doubt. Placing firmer constraints both on the methods used to identify and confirm IMBHs/SMBHs, as well as characterizing the range of host environments that IMBHs/SMBHs likely inhabit is therefore of considerable interest and importance. Additionally, finding significant numbers of IMBHs in metal-poor systems would be particularly intriguing, since such systems may represent local analogs of primordial galaxies, and therefore could provide clues of early accretion processes. Aims: Here we study in detail several candidate active galactic nuclei (AGN) found in metal-poor hosts. Methods: We utilize new X-ray and optical observations to characterize these metal-poor AGN candidates and compare them against known AGN luminosity relations and well-characterized IMBH/SMBH samples. Results: Despite having clear broad optical emission lines that are long-lived (≳10-13 yr), these candidate AGN appear to lack associated strong X-ray and hard UV emission, lying at least 1-2 dex off the known AGN correlations. If they are IMBHs/SMBHs, our constraints imply that they either are not actively accreting, their accretion disks are fully obscured along our line-of-sight, or their accretion disks are not producing characteristic high energy emission. Alternatively, if they are not AGN, then their luminous broad emission lines imply production by extreme stellar processes. The latter would have profound implications on the applicability of broad lines for mass estimates of massive black holes. The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A64

  12. Resolving AGN with PanSTARRS transients

    NASA Astrophysics Data System (ADS)

    Lawrence, Andy

    2012-10-01

    With PanSTARRS we have discovered a new class of slow, blue nuclear transients which we believe to be rare examples of background AGN microlensed by stars in foreground galaxies, amplified by a factor of 10--100. The background AGN should be somewhat resolved by the foreground lens, providing a unique new diagnostic of AGN size and structure - the UV, optical, IR, BLR, and X-ray regions should have differing evolutions during the event. This proposal is a first step towards understanding the structure of the X-ray source : testing the microlensing hypothesis, characterising the SED, and establishing the first two epochs in an expected gradual decline.

  13. Photometric AGN reverberation mapping - an efficient tool for BLR sizes, black hole masses, and host-subtracted AGN luminosities

    NASA Astrophysics Data System (ADS)

    Haas, M.; Chini, R.; Ramolla, M.; Pozo Nuñez, F.; Westhues, C.; Watermann, R.; Hoffmeister, V.; Murphy, M.

    2011-11-01

    Photometric reverberation mapping employs a wide band pass to measure the AGN continuum variations and a suitable narrow band to trace the echo of an emission line in the broad line region (BLR). The narrow band catches both the emission line and the underlying continuum, and one needs to extract the pure emission line light curve. We performed a test on two local AGNs, PG0003+199 and Ark120, by observing well-sampled broad- (B, V) and narrow-band light curves with the robotic 15 cm telescope VYSOS-6 on Cerro Armazones, Chile. We find that, as long as the emission line contributes 50% to the band pass, the pure emission line light curve can be reconstructed from photometric monitoring data so that the time lag τ can be measured. For both objects the lags are consistent with spectroscopic reverberation results. We calculated virial black hole masses in agreement with literature values, by combining the BLR size RBLR (τ) from photometric monitoring with the velocity dispersion of a single contemporaneous spectrum. Applying the flux variation gradient method, we estimate the host galaxy contribution in the apertures used and the host-subtracted restframe 5100 Å luminosity LAGN. Our LAGN differs significantly from previous estimates, placing both sources ~50% closer to the RBLR - LAGN relation. This suggests that the scatter in the current RBLR - LAGN relation is largely caused by uncertainties in RBLR due to undersampled light curves and by uncertainties in the host-subtracted AGN luminosities inferred so far. If the scatter can be reduced, then two quasar samples matching in RBLR should also match in intrinsic LAGN, independent of redshift, thus offering the prospect of probing cosmological models. Photometric reverberation mapping opens the door to efficiently measuring hundreds of BLR sizes and host-subtracted AGN luminosities even with small telescopes, but also routinely with upcoming large survey telescopes like the LSST.

  14. 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.

  15. 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.

  16. Sizes and Kinematics of Extended Narrow-line Regions in Luminous Obscured AGN Selected by Broadband Images

    NASA Astrophysics Data System (ADS)

    Sun, Ai-Lei; Greene, Jenny E.; Zakamska, Nadia L.

    2017-02-01

    To study the impact of active galactic nuclei (AGN) feedback on their galactic ISM, we present Magellan long-slit spectroscopy of 12 luminous nearby obscured AGN ({L}{bol}∼ {10}45.0-46.5 {erg} {{{s}}}-1, z ∼ 0.1). These objects are selected from a parent sample of spectroscopically identified AGN to have high [O iii]λ5007 and Wide-field Infrared Survey Explorer mid-IR luminosities and extended emission in the Sloan Digital Sky Survey r-band images, suggesting the presence of extended [O iii]λ5007 emission. We find spatially resolved [O iii] emission (2–35 kpc) in 8 out of 12 of these objects. Combined with samples of higher luminosity obscured AGN, we confirm that the size of the narrow-line region (RNLR) scales with the mid-IR luminosity until the relation flattens at RNLR ∼ 10 kpc. Nine out of 12 objects in our sample have regions with broad [O iii] line widths (w80 > 600 km s‑1), indicating outflows. We define these regions as the kinematically disturbed region (KDR). The size of the KDR ({R}{KDR}) is typically smaller than RNLR by few kiloparsecs but also correlates strongly with the AGN mid-IR luminosity. Given the uncertain outflow mass, we derive a loose constraint on the outflow energy efficiency {η }{med}=\\dot{E}/{L}{bol}∼ 0.007 % {--}7 % . We find no evidence for an AGN luminosity threshold below which outflows are not launched. To explain the sizes, velocity profiles, and high occurrence rates of the outflows in the most luminous AGN, we propose a scenario in which energy-conserving outflows are driven by AGN episodes with ∼108 year durations. Within each episode, the AGN is unlikely to be constantly luminous but could flicker on shorter timescales (≲107 yr) with a moderate duty cycle (∼10%).

  17. 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.

  18. 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.

  19. Astrometric Evidence for a Population of Dislodged AGNs

    NASA Astrophysics Data System (ADS)

    Makarov, Valeri V.; Frouard, Julien; Berghea, Ciprian T.; Rest, Armin; Chambers, Kenneth C.; Kaiser, Nicholas; Kudritzki, Rolf-Peter; Magnier, Eugene A.

    2017-02-01

    We investigate a sample of 2293 ICRF2 extragalactic radio-loud sources with accurate positions determined by VLBI, mostly active galactic nuclei (AGNs) and quasars, which are cross-matched with optical sources in the first Gaia release (Gaia DR1). The distribution of offsets between the VLBI sources and their optical counterparts is strongly non-Gaussian, with powerful wings extending beyond 1 arcsec. Limiting our analysis to only high-confidence difference detections, we find (and publish) a list of 188 objects with normalized variances above 12 and offsets below 1 arcsec. Pan-STARRS stacked and monochromatic images resolve some of these sources, indicating the presence of double sources, confusion sources, or pronounced extended structures. Some 89 high-quality objects, however, do not show any perturbations and appear to be star-like single sources, yet they are displaced by multiples of the expected error from the radio-loud AGN. We conclude that a fraction of luminous AGNs (more than 4%) can be physically dislodged from the optical centers of their parent galaxies.

  20. AGN POPULATION IN HICKSON COMPACT GROUPS. I. DATA AND NUCLEAR ACTIVITY CLASSIFICATION

    SciTech Connect

    MartInez, M. A.; Del Olmo, A.; Perea, J.; Coziol, R. E-mail: chony@iaa.es E-mail: rcoziol@astro.ugto.mx

    2010-03-15

    We have conducted a new spectroscopic survey to characterize the nature of nuclear activity in Hickson compact group (HCG) galaxies and establish its frequency. We have obtained new intermediate-resolution optical spectroscopy for 200 member galaxies and corrected for underlying stellar population contamination using galaxy templates. Spectra for 11 additional galaxies have been acquired from the ESO and 6dF public archives, and emission-line ratios have been taken from the literature for 59 more galaxies. Here we present the results of our classification of the nuclear activity for 270 member galaxies, which belong to a well-defined sample of 64 HCGs. We found a large fraction of galaxies, 63%, with emission lines. Using standard diagnostic diagrams, 45% of the emission-line galaxies were classified as pure active galactic nuclei (AGNs), 23% as Transition Objects (TOs), and 32% as star-forming nuclei (SFNs). In the HCGs, the AGN activity appears as the most frequent activity type. Adopting the interpretation that in TOs a low-luminosity AGN coexists with circumnuclear star formation, the fraction of galaxies with an AGN could rise to 42% of the whole sample. The low frequency (20%) of SFNs confirms that there is no star formation enhancement in HCGs. After extinction correction, we found a median AGN H{alpha} luminosity of 7.1 x 10{sup 39} erg s{sup -1}, which implies that AGNs in HCG have a characteristically low luminosity. This result added to the fact that there is an almost complete absence of broad-line AGNs in compact groups (CGs) as found by MartInez et al. and corroborated in this study for HCGs, is consistent with very few gas left in these galaxies. In general, therefore, what may characterize the level of activity in CGs is a severe deficiency of gas.

  1. 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.

  2. Dust-deficient Palomar-Green Quasars and the Diversity of AGN Intrinsic IR Emission

    NASA Astrophysics Data System (ADS)

    Lyu, Jianwei; Rieke, G. H.; Shi, Yong

    2017-02-01

    To elucidate the intrinsic broadband infrared (IR) emission properties of active galactic nuclei (AGNs), we analyze the spectral energy distributions (SEDs) of 87 z ≲ 0.5 Palomar-Green (PG) quasars. While the Elvis AGN template with a moderate far-IR correction can reasonably match the SEDs of the AGN components in ∼60% of the sample (and is superior to alternatives such as that by Assef), it fails on two quasar populations: (1) hot-dust-deficient (HDD) quasars that show very weak emission thoroughly from the near-IR to the far-IR, and (2) warm-dust-deficient (WDD) quasars that have similar hot dust emission as normal quasars but are relatively faint in the mid- and far-IR. After building composite AGN templates for these dust-deficient quasars, we successfully fit the 0.3–500 μm SEDs of the PG sample with the appropriate AGN template, an infrared template of a star-forming galaxy, and a host galaxy stellar template. 20 HDD and 12 WDD quasars are identified from the SED decomposition, including seven ambiguous cases. Compared with normal quasars, the HDD quasars have AGNs with relatively low Eddington ratios and the fraction of WDD quasars increases with AGN luminosity. Moreover, both the HDD and WDD quasar populations show relatively stronger mid-IR silicate emission. Virtually identical SED properties are also found in some quasars from z = 0.5 to 6. We propose a conceptual model to demonstrate that the observed dust deficiency of quasars can result from a change of structures of the circumnuclear tori that can occur at any cosmic epoch.

  3. The view of AGN-host alignment via reflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Middleton, Matthew J.; Parker, Michael L.; Reynolds, Christopher S.; Fabian, Andrew C.; Lohfink, Anne M.

    2016-04-01

    The fuelling of active galactic nuclei (AGN) - via material propagated through the galactic disc or via minor mergers - is expected to leave an imprint on the alignment of the sub-pc disc relative to the host galaxy's stellar disc. Determining the inclination of the inner disc usually relies on the launching angle of the jet; here instead we use the inclination derived from reflection fits to a sample of AGN. We determine the distorting effect of unmodelled Fe XXV/XXVI features and, via extensive simulations, determine the difference in disc inclination resulting from the use of RELXILL compared to REFLIONX. We compare inner disc inclinations to those for the host galaxy stellar disc derived from the Hubble formula and, via Monte Carlo simulations, find a strong lack of a correlation (at ≫5σ) implying either widespread feeding via mergers if we assume the sample to be homogeneous, or that radiative disc warps are distorting our view of the emission. However, we find that by removing a small (˜1/5) subset of AGN, the remaining sample is consistent with random sampling of an underlying 1:1 correlation (at the 3σ level). A heterogenous sample would likely imply that our view is not dominated by radiative disc warps but instead by different feeding mechanisms with the majority consistent with coplanar accretion (although this may be the result of selection bias), whilst a smaller but not insignificant fraction may have been fuelled by minor mergers in the recent history of the host galaxy.

  4. VizieR Online Data Catalog: AGN 2.5-11um spectroscopy (Clavel+, 2000)

    NASA Astrophysics Data System (ADS)

    Clavel, J.; Schulz, B.; Altieri, B.; Barr, P.; Claes, P.; Heras, A.; Leech, K.; Metcalfe, L.; Salama, A.

    2000-03-01

    We present observations over the 2.5-11μm range, with the ISOPHOT-S spectrometer and the ISOCAM imaging camera, of a sample of 57 AGNs and one non-active SB galaxy. The sample is about equally divided into type I (<=1.5 28 sources) and type II (>1.5 29 sources) objects. (4 data files).

  5. 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.

  6. Mergers as triggers for nuclear activity: a near-IR study of the close environment of AGN in the VISTA-VIDEO survey

    NASA Astrophysics Data System (ADS)

    Karouzos, M.; Jarvis, M. J.; Bonfield, D.

    2014-03-01

    There is an ongoing debate concerning the driver of nuclear activity in galaxies, with active galactic nuclei (AGN) either being triggered by major or minor galactic mergers or, alternatively, through secular processes like cold gas accretion and/or formation of bars. We investigate the close environment of active galaxies selected in the X-ray, the radio and the mid-IR. We utilize the first data release of the new near-IR VISTA Deep Extragalactic Observations (VIDEO) survey of the XMM-Large Scale Structure field. We use two measures of environment density, namely counts within a given aperture and a finite redshift slice (pseudo-3D density) and closest neighbour density measures Σ2 and Σ5. We select both AGN and control samples, matching them in redshift and apparent Ks-band magnitude. We find that AGN are found in a range of environments, with a subset of the AGN samples residing in overdense environments. Seyfert-like X-ray AGN and flat-spectrum radio-AGN are found to inhabit significantly overdense environments compared to their control sample. The relation between overdensities and AGN luminosity does not however reveal any positive correlation. Given the absence of an environment density-AGN luminosity relation, we find no support for a scheme where high-luminosity AGN are preferentially triggered by mergers. On the contrary, we find that AGN likely trace over dense environments at high redshift due to the fact that they inhabit the most massive galaxies, rather than being an AGN.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Probing the Black Hole-Galaxy Connection with AGN Host Galaxy Morphologies

    NASA Astrophysics Data System (ADS)

    Simmons, Brooke; Urry, C. M.; COSMOS Team

    2006-12-01

    There is increasing evidence that galaxies and supermassive black holes form and evolve together, exerting mutual feedback that governs the galaxy dynamics and the black hole mass. During their growth phase, supermassive black holes are readily visible as Active Galactic Nuclei (AGN). The morphologies of AGN host galaxies offer a powerful, direct probe of the AGN-galaxy connection. We are carrying out morphological analysis of large AGN samples from deep multi-wavelength surveys, comparing the results to well-selected samples of inactive galaxies. To interpret the results properly requires understanding the observational bias introduced by the central point source, which can hide compact features and thus influence the extracted AGN host morphological parameters. Therefore, we performed extensive simulations, involving a variety of galaxy types over a range of redshifts. Here we present results of these simulations and describe preliminary work on deep HST ACS images from the COSMOS field. We gratefully acknowledge support from HST grants AR-10689.01-A and GO-09822.09-A, and Yale University.

  12. Probing the Black Hole-Galaxy Connection with AGN Host Galaxy Morphologies

    NASA Astrophysics Data System (ADS)

    Simmons, Brooke; Urry, C. M.; COSMOS Team

    2007-05-01

    There is increasing evidence that galaxies and supermassive black holes form and evolve together, exerting mutual feedback that governs the galaxy dynamics and the black hole mass. During their growth phase, supermassive black holes are readily visible as Active Galactic Nuclei (AGN). The morphologies of AGN host galaxies offer a powerful, direct probe of the AGN-galaxy connection. We are carrying out morphological analysis of large AGN samples from deep multi-wavelength surveys, comparing the results to well-selected samples of inactive galaxies. To interpret the results properly requires understanding the observational bias introduced by the central point source, which can hide compact features and thus influence the extracted AGN host morphological parameters. Therefore, we performed extensive simulations, involving a variety of galaxy types over a range of redshifts. Here we present results of these simulations and describe preliminary work on deep HST ACS images from the COSMOS field. We gratefully acknowledge support from HST grants AR-10689.01-A and GO-09822.09-A, and Yale University.

  13. Optically faint radio sources: reborn AGN?

    NASA Astrophysics Data System (ADS)

    Filho, M. E.; Brinchmann, J.; Lobo, C.; Antón, S.

    2011-12-01

    We present our discovery of several relatively strong radio sources in the field-of-view of SDSS galaxy clusters that have no optical counterparts down to the magnitude limits of the SDSS. The optically faint radio sources appear as double-lobed or core-jet objects in the FIRST radio images and have projected angular sizes ranging from 0.5 to 1.0 arcmin. We followed-up these sources with near-infrared imaging using the wide-field imager HAWK-I on the VLT. We detected Ks-band emitting regions, about 1.5 arcsec in size and coincident with the centers of the radio structures, in all sources, with magnitudes in the range 17-20 mag. We used spectral modelling to characterize the sample sources. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with those of moderate to high redshift (z < 4) gigahertz-peaked spectrum sources. Our results suggest that these unusual objects are galaxies whose black hole has been recently re-ignited but that retain large-scale radio structures, which are signatures of previous AGN activity.

  14. 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

  15. The Limited Impact of Outflows: Integral-field Spectroscopy of 20 Local AGNs

    NASA Astrophysics Data System (ADS)

    Bae, Hyun-Jin; Woo, Jong-Hak; Karouzos, Marios; Gallo, Elena; Flohic, Helene; Shen, Yue; Yoon, Suk-Jin

    2017-03-01

    To investigate active galactic nucleus (AGN) outflows as a tracer of AGN feedback on star formation, we perform integral-field spectroscopy of 20 type 2 AGNs at z < 0.1, which are luminous AGNs with [O iii] luminosity > 10{}41.5 erg s‑1 that exhibit strong outflow signatures in the [O iii] kinematics. By decomposing the emission-line profile, we obtain the maps of the narrow and broad components of the [O iii] and Hα lines, respectively. The broad components in both [O iii] and Hα represent the nongravitational kinematics, that is, gas outflows, while the narrow components, especially in Hα, represent the gravitational kinematics, that is, the rotational disk. By using the integrated spectra within the flux-weighted size of the narrow-line region, we estimate the energetics of the gas outflows. The ionized gas mass is 1.0–38.5 × {10}5{M}ȯ , and the mean mass outflow rate is 4.6 ± 4.3 M ⊙ yr‑1, which is a factor of ∼260 higher than the mean mass accretion rate of 0.02 ± 0.01 {M}ȯ yr‑1. The mean energy injection rate of the sample is 0.8% ± 0.6% of the AGN bolometric luminosity {L}{bol}, while the momentum flux is (5.4 ± 3.6) × {L}{bol}/c on average, except for the two most kinematically energetic AGNs with low {L}{bol}, which are possibly due to the dynamical timescale of the outflows. The estimated outflow energetics are consistent with the theoretical expectations for energy-conserving outflows from AGNs, yet we find no supporting evidence of instantaneous quenching of star formation due to the outflows.

  16. 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.

  17. 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⊙.

  18. 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.

  19. 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.

  20. 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.

  1. Radio continuum properties of luminous infrared galaxies. Identifying the presence of an AGN in the radio

    NASA Astrophysics Data System (ADS)

    Vardoulaki, E.; Charmandaris, V.; Murphy, E. J.; Diaz-Santos, T.; Armus, L.; Evans, A. S.; Mazzarella, J. M.; Privon, G. C.; Stierwalt, S.; Barcos-Muñoz, L.

    2015-02-01

    Context. Luminous infrared galaxies (LIRGs) are systems enshrouded in dust, which absorbs most of their optical/UV emission and radiates it again in the mid- and far-infrared. Radio observations are largely unaffected by dust obscuration, enabling us to study the central regions of LIRGs in an unbiased manner. Aims: The main goal of this project is to examine how the radio properties of local LIRGs relate to their infrared spectral characteristics. Here we present an analysis of the radio continuum properties of a subset of the Great Observatories All-sky LIRG Survey (GOALS), which consists of 202 nearby systems (z< 0.088). Our radio sample consists of 35 systems, containing 46 individual galaxies, that were observed at both 1.49 and 8.44 GHz with the VLA with a resolution of about 1 arcsec (FWHM). The aim of the project is to use the radio imagery to probe the central kpc of these LIRGs in search of active galactic nuclei (AGN). Methods: We used the archival data at 1.49 and 8.44 GHz to create radio-spectral-index maps using the standard relation between flux density Sν and frequency ν, Sν ~ ν- α, where α is the radio spectral index. By studying the spatial variations in α, we classified the objects as radio-AGN, radio-SB, and AGN/SB (a mixture). We identified the presence of an active nucleus using the radio morphology, deviations from the radio/infrared correlation, and spatially resolved spectral index maps, and then correlated this to the usual mid-infrared ([NeV]/[NeII] and [OIV]/[NeII] line ratios and equivalent width of the 6.2 μm PAH feature) and optical (BPT diagram) AGN diagnostics. Results: We find that 21 out of the 46 objects in our sample (~45%) are radio-AGN, 9 out of the 46 (~20%) are classified as starbursts (SB) based on the radio analysis, and 16 (~35%) are AGN/SB. After comparing to other AGN diagnostics we find 3 objects out of the 46 (~7%) that are identified as AGN based on the radio analysis, but are not classified as such based on

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. A spectral energy distribution analysis of AGN host galaxies in the Chandra-COSMOS Legacy Survey

    NASA Astrophysics Data System (ADS)

    Suh, Hyewon; Civano, Francesca M.; Hasinger, Guenther; Elvis, Martin; Marchesi, Stefano

    2015-01-01

    We present the host galaxy properties of a large sample of ~ 4000 X-ray selected Active Galactic Nuclei (AGN) in the Chandra COSMOS Legacy Survey to investigate the connection between BH accretion and host galaxy. The COSMOS Legacy survey reaching X-ray fluxes of 2x10-16 (cgs) in the 0.5-2 keV band, bridges the gap between large area shallow surveys and pencil beamed one. Making use of the existing multi-wavelength photometric data available for 96.6% of the sources, COSMOS Legacy survey provides a uniquely large sample to derive host galaxy properties for both obscured and unobscured sources. We perform a multi-component modeling from far-infrared (500 μm) when available to UV (1500 Å) using a 3-component fitting (nuclear hot dust, galaxy and starburst components) for obscured AGN and a 4-component fitting (nuclear hot dust, AGN big blue bump, galaxy, and starburst components) for unobscured AGN. Galaxy templates are from the stellar population synthesis models of Bruzual & Charlot (2003), nuclear hot dust templates are taken from Silva et al. (2004), and AGN big blue bump templates are from Richards et al. (2006). We use the column density information measured in the X-ray to constrain the AGN in the infrared band when available. Through detailed analysis of the broad-band spectral energy distribution, we derive the stellar masses and the star formation rates of the host galaxy as well as the nuclear and galaxy contribution at each frequency. We study the dependence of host galaxy properties on redshifts, luminosities, and black hole masses to infer the growth history of galaxies and black holes and we compare with a sample of inactive galaxies.

  7. Revealing AGN, young and old stellar populations in HzRGs with PEGASE.3

    NASA Astrophysics Data System (ADS)

    Drouart, Guillaume; De Breuck, Carlos; Vernet, Joël; Volmerange, Brigitte Rocca; Seymour, Nicholas

    2014-07-01

    The HeRGÉ (Herschel Radio Galaxy Evolution) project consists of a sample of 70 radio galaxies in the range 1 < z < 5.2. They benefit from continuous coverage from 3 to 870μm with Spitzer, Herschel and sub-mm ground-based instruments (SCUBA, LABOCA). As a calorimeter, IR is an excellent proxy to estimate the contribution of both AGN and starburst, making of radio galaxies perfect candidates to provide new insights into the relationship between AGN and their host galaxies. The IR SED fitting with empirical templates reveals that radio galaxies are luminous and that their black holes and their host galaxies are not growing simultaneously. Extending the SED to optical/near-IR on a subsample of 12 radio galaxies spanning 1 < z < 4 reveal the necessity of three components to reproduce the observations. Making use of the evolutionary code PEGASE.3 and an AGN torus model, we are able to estimate parameters from the AGN torus, the evolved stellar population and the starburst (SB). They reveal that radio galaxies are massive, evolved, forming the bulk of their mass at very high redshift in a short timescale, but experience episodic, strong SB events, often associated with an AGN activity.

  8. Clustering Of Radio-Selected AGN (And Star-Forming Galaxies) Up To Redshifts z = 3

    NASA Astrophysics Data System (ADS)

    Magliocchetti, Manuela; Popesso, P.; Brusa, M.; Salvato, M.

    2016-10-01

    We present the clustering properties of a complete sample of 957 radio sources detected by the VLA-COSMOS survey with radio fluxes brighter than 0.15 mJy. Based on their radio-luminosity, these objects have been furtherly divided into two populations of 642 AGN and 246 star-forming galaxies. Investigations of their clustering properties return values for the minimum masses of dark matter haloes capable to host at least one of such sources of Mmin=10^13.6 Msun for radio-selected AGN and Mmin=10^13.1 Msun for radio-emitting star-forming galaxies. Comparisons with previous works imply an independence of the clustering properties of the AGN population with respect to both radio luminosity and redshift. We also investigate the relationship between dark and luminous matter in both populations. Our results indicate a larger relative stellar content in the star-forming population with respect to AGN and also clearly show the cosmic process of star-formation build-up as one moves towards the more local universe. Comparisons between the observed space density of radio-selected AGN and that of dark matter haloes shows that about one in two haloes is associated with a black hole in its radio-active phase. This suggests that the radio-active phase is a recurrent phenomenon.

  9. A Hubble Space Telescope Survey of Intrinsic Absorption in Nearby AGN

    NASA Astrophysics Data System (ADS)

    Dashtamirova, Dzhuliya; Dunn, Jay P.; Crenshaw, D. Michael

    2017-01-01

    We present a survey of the intrinsic UV absorption lines in active galactic nuclei (AGN). We limit our study to the ultraviolet spectra of type 1 AGN with a redshift of z < 0.15 as a continuation of the Dunn et al. (2007, 2008) and Crenshaw et al. (1999) studies of smaller samples. We identify approximately 90 AGN fit our redshift specifications in the Mikulski Archive for Space Telescopes (MAST) database with Cosmic Origin Spectrograph (COS) observations. We download and co-add all of the COS spectra. We find that about 80 of these are type 1 AGN. We normalize the COS spectra and identify all of the intrinsic Lyman-alpha, N V, Si IV, and C IV intrinsic absorption features. From these data, we determine the fraction of type 1 AGN with intrinsic absorption in this redshift range and find the global covering factors of the absorbers. We also identify low ionization species as well as excited state lines. A number of objects have multiple epoch COS and/or Space Telescope Imaging Spectrograph (STIS) observations, which we use to investigate the absorption variability.

  10. Linking the radio and X-ray of AGN in cluster cores

    NASA Astrophysics Data System (ADS)

    Edge, Alastair; Sadler, Elaine; Combes, Francoise; Mahony, Elizabeth; Fabian, Andy; Hamer, Stephen; McDonald, Michael; Russell, Helen; Wilman, Richard; Hogan, Michael; Mcnamara, Brian; Hlavacek-larrondo, Julie; Grainge, Keith; Salomé, Philippe

    2013-04-01

    There is a growing body of evidence that there is a balance of cooling and heating in the cores of clusters of galaxies that is regulated by AGN activity in the central galaxy. X-ray observations show that gas cooling is suppressed but mm/sub-mm observations show that there is cold molecular gas that has apparently cooled from the ICM. The AGN activity generated when some of this cold gas reaches the supermassive black hole in the central galaxy goes on to heat the surrounding gas creating an "AGN feedback" cycle. One important element to this puzzle is what the intrinsic power of the AGN is and how it couples to the ICM. We propose to address both of these issues by determining the high frequency spectral properties of a sample of 20 of the brightest systems that are known to show X-ray emission from an active nucleus. These results can be used to determine the intrinsic power of the ensemble of clusters which can be compared to the predicted heating rate required to balance cooling. This comparison will place a strong constraint on the energetics of ICM heating from the AGN.

  11. 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.

    2017-01-01

    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 standardizable 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-d cadence and will run for 3 yr. 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 normalization 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.

  12. 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).

  13. 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.

  14. The WISSH Quasars Project: Probing the AGN-Galaxy Coevolution In the Most Luminous Quasars

    NASA Astrophysics Data System (ADS)

    Bischetti, Manuela; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Duras, F.; Martocchia, S.; Zappacosta, L.; Brusa, M.; Vignali, C.; Marconi, A.; Cresci, G.; WISSH Collaboration

    2016-10-01

    The WISE/SDSS selected hyper-luminous (WISSH) quasars survey is an extensive multiband observing program (from millimeter wavelengths to hard X rays) to investigate the role of nuclear activity in SMBH-galaxy self-regulated growth via extended outflows. Our ongoing project is designed to accurately constrain both AGN and host galaxy ISM properties in a large sample of 90 broad-line quasars at the brightest end of the AGN luminosity function (L_bol > 1e14 L_sun) and at the peak of their number density (z 2 - 4)I will review the most relevant results obtained to date with emphasis on the discovery of extremely powerful (up to 4% of L_bol) ionized outflows, the relation between AGN properties (obscuration, luminosity and Eddington ratio) and large-scale winds, and the SED of these hyper-luminous quasars.

  15. 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.

  16. Reverberation Mapping of AGN Accretion Disks

    NASA Astrophysics Data System (ADS)

    Fausnaugh, Michael; AGN STORM Collaboration

    2017-01-01

    I will discuss new reverberation mapping results that allow us to investigate the temperature structure of AGN accretion disks. By measuring time-delays between broad-band continuum light curves, we can determine the size of the disk as a function of wavelength. I will discuss the detection of continuum lags in NGC 5548 reported by the AGN STORM project and implications for the accretion disk. I will also present evidence for continuum lags in two other AGN for which we recently measured black hole masses from continuum-Hbeta reverberations. The mass measurements allow us to compare the continuum lags to predictions from standard thin disk theory, and our results indicate that the accretion disks are larger than the simplest expectations.

  17. Probing AGN Accretion History Through X-Ray Variability

    NASA Astrophysics Data System (ADS)

    Paolillo, Maurizio; Papadakis, I.; Brandt, W. N.; Xue, Y. Q.; Luo, B.; Tozzi, P.; Shemmer, O.; Allevato, V.; Bauer, F.; Koekemoer, A.; Vignali, C.; Vito, F.; Yang, G.; Wang, J. X.; Zheng, X.

    2016-10-01

    I will present recent results on AGN variability in the CDFS survey. Using over 10 years of X-ray monitoring and comparison with local AGNs we are able to constrain the variability dependence on BH mass and accreton rate, and use it to trace the accretion hisory of the AGN population up to z=3.

  18. 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

  19. 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).

  20. 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.

  1. 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.

  2. ON THE STAR FORMATION-AGN CONNECTION AT z {approx}< 0.3

    SciTech Connect

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

    2013-03-10

    Using the spectra of a sample of {approx}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] 5007 A 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'' 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 <1.7 kpc, when including a constant disk component, has a sub-linear dependence on SMBH accretion rate: SFR{proportional_to} M-dot {sup 0.36}, suggesting that angular momentum transfer through the disk limits accretion efficiency rather than the supply from stellar mass loss.

  3. Tracing the Far-Infrared Roles of AGN in Dusty Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Brown, Arianna; Nayyeri, Hooshang; Cooray, Asantha R.; Mitchell-Wynne, Ketron

    2017-01-01

    Active galactic nuclei (AGNs) are suggested to play an important role in quenching their host galaxy’s star formation rate (SFR) by heating up and/or consuming the cool gas necessary to create stars. This mechanism is theorized as a critical step in AGN evolutionary models. The efforts to study this effect suffer in part from low-number statistics at high x-ray luminosities (LXR > 1044 ergs/s) for AGNs at z≈1-3, and a lack of separately estimated SFRs for AGN in dusty, star-forming galaxies (DSFGs). In this work, we extend our analysis to build a more complete picture using the variety of available multi-wavelength data in the XBoötes region. The Chandra XBoötes Survey is a 5-ks X-ray survey of the 9.3 square degree Boötes Field of the NOAO Deep Wide-Field Survey, a survey imaged from the optical to the near-IR. We estimate AGN spectral energy distributions and SFRs for ~400 x-ray sources using available data in all four Spitzer IRAC bands, the Spitzer MIPS 24µm band, all five Herschel SPIRE and PACS bands, along with NEWFIRM optical bands. Preliminary results show an exponential correlation between x-ray luminosity and star formation. As a comparison, we will use a stacking technique for the ~500 x-ray sources that were not detected at submillimeter wavelengths, where sources are binned by x-ray luminosity. We will compare these two samples and expect to see a difference in slope. Using these techniques, we hope to place tighter constraints on the mean SFRs of high-luminosity AGNs inside DSFGs, and determine if x-ray luminosities are independent of average SFRs for our sample in the Boötes field.

  4. 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

  5. PS1-1000305 an AGN outburst?

    NASA Astrophysics Data System (ADS)

    Drake, A. J.; Mahabal, A. A.; Djorgovski, S. G.; Graham, M. J.; Williams, R.; Prieto, J.; Catelan, M.; Christensen, E.; Beshore, E. C.; Larson, S. M.

    2010-07-01

    Kankare et al. (2010, ATel#2716) recently reported the discovery of an AGN outburst (PS1-1000305) detected in PS1 taken data on May 19.3 UT. The redshift of the AGN is given by Kankare et al. as z=0.77 with the host galaxy SDSS J152844.16+425722.5. We have extracted the five year archival CSS/CRTS lightcurve at the location of PS1-1000305.

  6. Multi-Frequency View Of Jetted AGN

    NASA Astrophysics Data System (ADS)

    Giroletti, Marcello; Orienti, M.; D'Ammando, F.; Lico, R.; Giovannini, G.:

    2016-10-01

    I will present a review on the context and the most recent results about radio loud AGNs as seen in different parts of the electromagnetic spectrum, with an eye also to multi-messenger astrophysics and neutrinos in particular. I will focus on various topics of interest about RL AGNs, such as: the study of the physics of relativistic jets and particle acceleration, in particular through VLBI and gamma ray observations; the feedback to the host galaxy and on galaxy cluster scales; the possibility to probe distant and obscured environments.

  7. 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.

  8. 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.

  9. 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.

  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.

    2017-01-01

    We present medium resolution near-infrared spectroscopic observations of 41 obscured and intermediate class active galactic nuclei (AGN; type 2, 1.9 and 1.8; AGN2) with redshift z ≲ 0.1, selected from the Swift/Burst Alert Telescope 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 Infrared Spectrometer And Array Camera/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 full width at half-maximum (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. 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.

  12. 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.

  13. 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

    2016-12-01

    The interplay between cosmic gas accretion on to 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 centre 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 to be driven not only 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.

  14. 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.

  15. NuSTAR Observations of Bright AGNs

    NASA Astrophysics Data System (ADS)

    Elvis, Martin; Ballantyne, D. R.; Blandford, R. D.; Boggs, S.; Boydstun, K.; Brenneman, L.; Cappi, M.; Christensen, F.; Craig, W.; Fabian, A.; Fuerst, F.; Guainazzi, M.; Hailey, C. J.; Harrison, F.; Madejski, G. M.; Marinucci, A.; Matt, G.; Nandra, K.; Reynolds, C. S.; Stern, D.; Walton, D.; Zhang, W.; NuSTAR Team

    2013-01-01

    The dramatically improved signal-to-noise provided by NuSTAR up to ~80 keV allows a qualitative change in our understanding of the X-ray emission of Active Galactic Nuclei (AGNs). Despite intensive investigation for over 30 years, during which the 0.1-10 keV spectra and variability of AGNs have been mapped out in detail, we do not know the origin of the X-ray source in AGNs. The "standard model" of supermassive black hole, accretion disk and relativistic jet does not predict an X-ray source in a straightforward way. It is usually assumed that the X-rays were UV photons from the accretion disk that have been Compton up-scattered in a "hot corona", but the temperature, optical depth and geometry of this corona are unknown - if it exists. NuSTAR enables the measurement of the high energy cut-off of the X-ray spectrum, and so the corona temperature, to be measured precisely for the first time, and tests the relativistic Fe-K line and Compton reflection models. If this model is correct then, with Suzaku and XMM-Newton, NuSTAR can measure black hole spins to high accuracy. We outline the NuSTAR GTO program on bright, unobscured, AGNs including simultaneous observations with Suzaku and XMM-Newton, and show early data.

  16. 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…

  17. 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.

  18. THE CLUSTER AND FIELD GALAXY ACTIVE GALACTIC NUCLEUS FRACTION AT z = 1-1.5: EVIDENCE FOR A REVERSAL OF THE LOCAL ANTICORRELATION BETWEEN ENVIRONMENT AND AGN FRACTION

    SciTech Connect

    Martini, Paul; Miller, E. D.; Bautz, M.; Brodwin, M.; Stanford, S. A.; Gonzalez, Anthony H.; Hickox, R. C.; Stern, D.; Eisenhardt, P. R.; Galametz, A.; Norman, D.; Dey, A.; Jannuzi, B. T.; Murray, S.; Jones, C.; Brown, M. J. I.

    2013-05-01

    The fraction of cluster galaxies that host luminous active galactic nuclei (AGNs) is an important probe of AGN fueling processes, the cold interstellar medium at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M {>=} 10{sup 14} M{sub Sun }) at 1 < z < 1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the field fraction in the immediate vicinity of these clusters, and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z {approx} 3. We estimate that the cluster AGN fraction at 1 < z < 1.5 is f{sub A} = 3.0{sup +2.4}{sub -1.4}% for AGNs with a rest-frame, hard X-ray luminosity greater than L{sub X,{sub H}} {>=} 10{sup 44} erg s{sup -1}. This fraction is measured relative to all cluster galaxies more luminous than M{sup *}{sub 3.6}(z) + 1, where M{sup *}{sub 3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6 {mu}m bandpass. The cluster AGN fraction is 30 times greater than the 3{sigma} upper limit on the value for AGNs of similar luminosity at z {approx} 0.25, as well as more than an order of magnitude greater than the AGN fraction at z {approx} 0.75. AGNs with L{sub X,{sub H}} {>=} 10{sup 43} erg s{sup -1} exhibit similarly pronounced evolution with redshift. In contrast to the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1 < z < 1.5. This is evidence that the cluster AGN population has evolved more rapidly than the field population from z {approx} 1.5 to the present. This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field.

  19. 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.

  20. Excess AGN activity in the z = 2.30 Protocluster in HS 1700+64

    NASA Astrophysics Data System (ADS)

    Digby-North, J. A.; Nandra, K.; Laird, E. S.; Steidel, C. C.; Georgakakis, A.; Bogosavljević, M.; Erb, D. K.; Shapley, A. E.; Reddy, N. A.; Aird, J.

    2010-09-01

    We present the results of spectroscopic, narrow-band and X-ray observations of a z = 2.30 protocluster in the field of the QSO HS 1700+643. Using a sample of BX/MD galaxies, which are selected to be at z ~ 2.2-2.7 by their rest-frame ultraviolet colours, we find that there are five protocluster AGN which have been identified by characteristic emission-lines in their optical/near-IR spectra; this represents an enhancement over the field significant at >98.5 per cent confidence. Using a ~200-ks Chandra/ACIS-I observation of this field we detect a total of 161 X-ray point sources to a Poissonian false-probability limit of 4 × 10-6 and identify eight of these with BX/MD galaxies. Two of these are spectroscopically confirmed protocluster members and are also classified as emission-line AGN. When compared to a similarly selected field sample, the analysis indicates this is also evidence for an enhancement of X-ray selected BX/MD AGN over the field, significant at >99 per cent confidence. Deep Lyα narrow-band imaging reveals that a total of 4/123 Lyα emitters (LAEs) are found to be associated with X-ray sources, with two of these confirmed protocluster members and one highly likely member. We do not find a significant enhancement of AGN activity in this LAE sample over that of the field (result is significant at only 87 per cent confidence). The X-ray emitting AGN fractions for the BX/MD and LAE samples are found to be 6.9+9.2-4.4 and 2.9+2.9-1.6 per cent, respectively, for protocluster AGN with L2-10keV >= 4.6 × 1043 erg s-1 at z = 2.30. These findings are similar to results from the z = 3.09 protocluster in the SSA 22 field found by Lehmer et al. (2009), in that both suggest AGN activity is favoured in dense environments at z > 2.

  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. Detailed Analysis of Starburst and AGN Activity in Blue E/S0 Galaxies in RESOLVE

    NASA Astrophysics Data System (ADS)

    Bittner, Ashley; Snyder, Elaine M.; Kannappan, Sheila; Norman, Dara J.; Norris, Mark A.; Moffett, Amanda J.; Hoversten, Erik A.; Stark, David; RESOLVE Team

    2016-01-01

    We identify a population of ~120 blue E/S0 galaxies among the ~1350 galaxies that are targeted for spectroscopy and have measured morphologies in the highly complete REsolved Spectroscopy Of a Local Volume (RESOLVE) survey. Blue E/S0s are identified as being early type objects morphologically classified between E and S0/a that fall on the blue sequence. Most (~85%) of our blue E/S0s have stellar masses <10^10 M_sun. Using pPXF, we have measured the stellar velocity dispersions (sigma values) from high resolution 485 - 550 nm spectroscopy for ~15% of the blue E/S0 sample. Using three variations of the M_BH -- sigma relation, this kinematic subsample is estimated to typically host central black holes within the range log M_BH = 4-6 M_sun. Following up on previous suggestions of nuclear activity in the blue E/S0 population, we investigate nuclear starburst and/or AGN activity occurring within the full sample. Preliminary results from cross-checking known AGN catalogs with the blue E/S0 sample have revealed nuclear activity in ~20 of these galaxies based on heterogeneous criteria (BPT line ratio analysis, spectral line broadening, etc.), some of which may not entirely distinguish starburst from AGN activity. In an attempt to break the degeneracy between AGN and starburst activity, we perform detailed spectral analysis for a few of the galaxies with kinematic data. We also consider the viability of alternate AGN detection methods based on L_Edd estimates calculated from the M_BH estimates. This research has been supported by the National Science Foundation through the CAP REU Program (ACI-1156614) and the RESOLVE Survey (AST-0955368) as well as the National Space Grant College and Fellowship Program and the NC Space Grant Consortium.

  3. 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.

  4. 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.

  5. The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Celotti, A.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Costamante, L.; Cotter, G.; Cutini, S.; D'Elia, V.; Dermer, C. D.; de Angelis, A.; de Palma, F.; De Rosa, A.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lavalley, C.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Malaguti, G.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piranomonte, S.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stawarz, Ł.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Taylor, G. B.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Ubertini, P.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-01

    We present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.

  6. 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.

  7. AGN Coronae through a Jet Perspective

    NASA Astrophysics Data System (ADS)

    King, Ashley L.; Lohfink, Anne; Kara, Erin

    2017-02-01

    This paper presents an in-depth look at the jet and coronal properties of 41 active galactic nuclei (AGNs). Utilizing the highest quality NuSTAR, XMM-Newton, and NRAO VLA Sky Survey 1.4 GHz data, we find that the radio Eddington luminosity inversely scales with X-ray reflection fraction, and positively scales with the distance between the corona and the reflected regions in the disk. We next investigate a model fit to the data that predicts the corona is outflowing and propagates into the large-scale jet. We find this model describes the data well and predicts that the corona has mildly relativistic velocities, 0.04< β < 0.40. We discuss our results in the context of disk–jet connections in AGNs.

  8. 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.

  9. Infrared-faint radio sources in the SERVS deep fields. Pinpointing AGNs at high redshift

    NASA Astrophysics Data System (ADS)

    Maini, A.; Prandoni, I.; Norris, R. P.; Spitler, L. R.; Mignano, A.; Lacy, M.; Morganti, R.

    2016-12-01

    Context. Infrared-faint radio sources (IFRS) represent an unexpected class of objects which are relatively bright at radio wavelength, but unusually faint at infrared (IR) and optical wavelengths. A recent and extensive campaign on the radio-brightest IFRSs (S1.4 GHz≳ 10 mJy) has provided evidence that most of them (if not all) contain an active galactic nuclei (AGN). Still uncertain is the nature of the radio-faintest IFRSs (S1.4 GHz≲ 1 mJy). Aims: The scope of this paper is to assess the nature of the radio-faintest IFRSs, testing their classification and improving the knowledge of their IR properties by making use of the most sensitive IR survey available so far: the Spitzer Extragalactic Representative Volume Survey (SERVS). We also explore how the criteria of IFRSs can be fine-tuned to pinpoint radio-loud AGNs at very high redshift (z > 4). Methods: We analysed a number of IFRS samples identified in SERVS fields, including a new sample (21 sources) extracted from the Lockman Hole. 3.6 and 4.5 μm IR counterparts of the 64 sources located in the SERVS fields were searched for and, when detected, their IR properties were studied. Results: We compared the radio/IR properties of the IR-detected IFRSs with those expected for a number of known classes of objects. We found that IR-detected IFRSs are mostly consistent with a mixture of high-redshift (z ≳ 3) radio-loud AGNs. The faintest ones (S1.4 GHz 100 μJy), however, could be also associated with nearer (z 2) dust-enshrouded star-burst galaxies. We also argue that, while IFRSs with radio-to-IR ratios >500 can very efficiently pinpoint radio-loud AGNs at redshift 2 < z < 4, lower radio-to-IR ratios ( 100-200) are expected for higher redshift radio-loud AGNs.

  10. Unveiling slim accretion disc in AGN through X-ray and Infrared observations

    NASA Astrophysics Data System (ADS)

    Castelló-Mor, Núria; Kaspi, Shai; Netzer, Hagai; Du, Pu; Hu, Chen; Ho, Luis C.; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Wang, Jian-Min

    2017-01-01

    In this work, which is a continuation of Castello-Mor et al. (2016), we present new X-ray and infrared (IR) data for a sample of active galactic nuclei (AGN) covering a wide range in Eddington ratio over a small luminosity range. In particular, we rigorously explore the dependence of the optical-to-X-ray spectral index αOX and the IR-to-optical spectral index on the dimensionless accretion rate, dot{M}=dot{m}/η where dot{m}=LAGN/LEdd and η is the mass-to-radiation conversion efficiency, in low and high accretion rate sources. We find that the SED of the faster accreting sources are surprisingly similar to those from the comparison sample of sources with lower accretion rate. In particular: I) the optical-to-UV AGN SED of slow and fast accreting AGN can be fitted with thin AD models. II) The value of αOX is very similar in slow and fast accreting systems up to a dimensionless accretion rate dot{M}c ˜10. We only find a correlation between αOX and dot{M} for sources with dot{M}>dot{M}c. In such cases, the faster accreting sources appear to have systematically larger αOX values. III) We also find that the torus in the faster accreting systems seems to be less efficient in reprocessing the primary AGN radiation having lower IR-to-optical spectral slopes. These findings, failing to recover the predicted differences between the SEDs of slim and thin ADs within the observed spectral window, suggest that additional physical processes or very special geometry act to reduce the extreme UV radiation in fast accreting AGN. This may be related to photon trapping, strong winds, and perhaps other yet unknown physical processes.

  11. 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

  12. 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.

  13. 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.

  14. Effects of Metallicity and AGN Activity on the Mid-Infrared Dust Emission of Galaxies

    NASA Astrophysics Data System (ADS)

    Wu, Hong; Zhu, Yi-Nan; Cao, Chen; Qin, Bo

    2007-10-01

    Using a sample of the Spitzer SWIRE-field galaxies whose optical spectra are taken from Data Release 4 of the Sloan Digital Sky Survey, we study possible correlations between the mid-infrared (MIR) dust emission from these galaxies and both their metallicities and AGN activities. We find that both metallicity and AGN activity are well correlated with the following ratios: PAH-to-star, VSG-to-star, and PAH-to-VSG, which can be characterized by νLν[8 μm(dust)]/νLν[3.6 μm], νLν[24 μm]/νLν[3.6 μm], and νLν[8 μm(dust)]/νLν[24 μm], respectively. We argue that our MIR-metallicity correlation could be explained by either the amount of dust (ongoing dust formation) or dust destruction (PAHs and VSGs could be destroyed by hard and intense radiation fields), and that the MIR-AGN correlation could arise due to either PAH destruction or an enhanced VSG continuum by the central AGN.

  15. Microvariability in AGNs: study of different statistical methods I. Observational Analysis

    NASA Astrophysics Data System (ADS)

    Zibecchi, L.; Andruchow, I.; Cellone, S. A.; Carpintero, D. D.; Romero, G. E.; Combi, J. A.

    2017-01-01

    We present the results of a study of different statistical methods currently used in the literature to analyse the (micro)variability of active galactic nuclei (AGNs) from ground-based optical observations. In particular, we focus on the comparison between the results obtained by applying the so-called C and F statistics, which are based on the ratio of standard deviations and variances, respectively. The motivation for this is that the implementation of these methods leads to different and contradictory results, making the variability classification of the light curves of a certain source dependent on the statistics implemented. For this purpose, we re-analyse the results on an AGN sample observed along several sessions with the 2.15-m `Jorge Sahade' telescope (CASLEO), San Juan, Argentina. For each AGN we constructed the nightly differential light curves. We thus obtained a total of 78 light curves for 39 AGNs, and we then applied the statistical tests mentioned above, in order to re-classify the variability state of these light curves and in an attempt to find the suitable statistical methodology to study photometric (micro)variations. We conclude that, although the C criterion is not proper a statistical test, it could still be a suitable parameter to detect variability and that its application allows to get more reliable variability results, in contrast with the F test.

  16. Discovering highly obscured AGN with the Swift-BAT 100-month survey

    NASA Astrophysics Data System (ADS)

    Marchesi, Stefano; Ajello, Marco; Comastri, Andrea; Cusumano, Giancarlo; La Parola, Valentina; Segreto, Alberto

    2017-01-01

    In this talk, I present a new technique to find highly obscured AGN using the 100-month Swift-BAT survey. I will show the results of the combined Chandra and BAT spectral analysis in the 0.3-150 keV band of seven Seyfert 2 galaxies selected from the 100-month BAT catalog. We selected nearby (z<0.03) sources lacking of a ROSAT counterpart and never previously observed in the 0.3-10 keV energy range. All the objects are significantly obscured, having NH>1E23 cm-2 at a >99% confidence level, and one to three sources are candidate Compton thick Active Galactic Nuclei (CT-AGN), i.e., have NH>1E24 cm-2.Since the selection criteria we adopted have been extremely effective in detecting highly obscured AGN, further observations of these and other Seyfert 2 galaxies selected from the BAT 100-month catalog will allow us to create a statistically significant sample of highly obscured AGN, therefore better understanding the physics of the obscuration processes.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Radio Properties of the BAT AGNs: the FIR-radio Relation, the Fundamental Plane, and the Main Sequence of Star Formation

    NASA Astrophysics Data System (ADS)

    Smith, Krista Lynne; Mushotzky, Richard F.; Vogel, Stuart; Shimizu, Thomas T.; Miller, Neal

    2016-12-01

    We conducted 22 GHz 1″ JVLA imaging of 70 radio-quiet active galactic nuclei (AGNs) from the Swift-BAT survey. We find radio cores in all but three objects. The radio morphologies of the sample fall into three groups: compact and core-dominated, extended, and jet-like. We spatially decompose each image into core flux and extended flux, and compare the extended radio emission with that predicted from previous Herschel observations using the canonical FIR-radio relation. After removing the AGN contribution to the FIR and radio flux densities, we find that the relation holds remarkably well despite the potentially different star formation physics in the circumnuclear environment. We also compare our core radio flux densities with predictions of coronal models and scale-invariant jet models for the origin of radio emission in radio-quiet AGNs, and find general consistency with both models. However, we find that the L R/L X relation does not distinguish between star formation and non-relativistic AGN-driven outflows as the origin of radio emission in radio-quiet AGNs. Finally, we examine where objects with different radio morphologies fall in relation to the main sequence (MS) of star formation, and conclude that those AGNs that fall below the MS, as X-ray selected AGNs have been found to do, have core-dominated or jet-like 22 GHz morphologies.

  2. Intermediate inclinations of type 2 Coronal-Line Forest AGN

    NASA Astrophysics Data System (ADS)

    Rose, Marvin; Elvis, Martin; Crenshaw, Michael; Glidden, Ana

    2015-07-01

    Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are remarkable in the sense that they have a rich spectrum of dozens of coronal emission lines (e.g. [Fe VII], [Fe X] and [Ne V]) in their spectra. Rose, Elvis & Tadhunter suggest that the inner obscuring torus wall is the most likely location of the coronal line region in CLiF AGN, and the unusual strength of the forbidden high-ionization lines is due to a specific AGN-torus inclination angle. Here, we test this suggestion using mid-IR colours (4.6-22 μm) from the Wide-Field Infrared Survey Explorer for the CLiF AGN. We use the Fischer et al. result that showed that as the AGN-torus inclination becomes more face on, the Spitzer 5.5-30 μm colours become bluer. We show that the [W2-W4] colours for the CLiF AGN (<[W2-W4]> = 5.92 ± 0.12) are intermediate between Sloan Digital Sky Survey (SDSS) type 1 (<[W2-W4]> = 5.22 ± 0.01) and type 2 AGN (<[W2-W4]> = 6.35 ± 0.03). This implies that the AGN-torus inclinations for the CLiF AGN are indeed intermediate, supporting the work of Rose, Elvis & Tadhunter. The confirmed relation between CLiF AGN and their viewing angle shows that CLiF AGN may be useful for our understanding of AGN unification.

  3. 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.

  4. 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

  5. HEAVILY OBSCURED AGN IN STAR-FORMING GALAXIES AT z approx = 2

    SciTech Connect

    Treister, E.; Kartaltepe, Jeyhan; Le Floc'h, Emeric; Cardamone, Carolin N.; Schawinski, Kevin; Urry, C. Megan; Virani, Shanil; Gawiser, Eric; Lira, Paulina; Damen, Maaike; Taylor, Edward N.; Justham, Stephen; Koekemoer, Anton M.

    2009-11-20

    We study the properties of a sample of 211 heavily obscured active galactic nucleus (AGN) candidates in the extended Chandra Deep Field-South selecting objects with f {sub 24m}u{sub m}/f{sub R} > 1000 and R - K>4.5. Of these, 18 were detected in X-rays and found to be obscured AGNs with neutral hydrogen column densities of approx10{sup 23} cm{sup -2}. In the X-ray-undetected sample, the following evidence suggests a large fraction of heavily obscured (Compton-thick) AGN: (1) The stacked X-ray signal of the sample is strong, with an observed ratio of soft to hard X-ray counts consistent with a population of approx90% heavily obscured AGNs combined with 10% star-forming galaxies. (2) The X-ray-to-mid-IR ratios for these sources are significantly larger than that of star-forming galaxies and approx2 orders of magnitude smaller than for the general AGN population, suggesting column densities of N {sub H} approx> 5 x 10{sup 24} cm{sup -2}. (3) The Spitzer near- and mid-IR colors of these sources are consistent with those of the X-ray-detected samples if the effects of dust self-absorption are considered. Spectral fitting to the rest-frame UV/optical light (dominated by the host galaxy) returns stellar masses of approx10{sup 11} M{sub sun} and (E(B - V)) = 0.5, and reveals evidence for a significant young stellar population, indicating that these sources are experiencing considerable star formation. This sample of heavily obscured AGN candidates implies a space density at z approx 2 of approx10{sup -5} Mpc{sup -3}, finding a strong evolution in the number of L{sub X} >10{sup 44} erg s{sup -1} sources from z = 1.5 to 2.5, possibly consistent with a short-lived heavily obscured phase before an unobscured quasar is visible.

  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. HOT DUST OBSCURED GALAXIES WITH EXCESS BLUE LIGHT: DUAL AGN OR SINGLE AGN UNDER EXTREME CONDITIONS?

    SciTech Connect

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

    2016-03-10

    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{sub ⊙} yr{sup −1}. Deep polarimetry observations could confirm the reflection hypothesis.

  8. Nebular Emission From AGN In The Ultraviolet/Optical: Linking Observations and Theory With New Generation Spectral Models

    NASA Astrophysics Data System (ADS)

    Feltre, Anna; Charlot, S.; Gutkin, J.; Hirschmann, M.; Mignoli, M.; Calura, F.; Gilli, R.; Bongiorno, A.; NEOGAL Team

    2016-10-01

    Spectroscopic studies of 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 the 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 present how the nebular emission from both young stars and AGN can be coupled with a new set of cosmological hydrodynamical zoom-in simulations of massive galaxies to achieve a better understanding of black hole growth and galaxy evolution with cosmic time. I will also present an innovative Bayesian fitting code that can help us best interpret current, and future, spectro-photometric data on active galaxies. In particular, the implementation of AGN photoionization calculations within this fitting tool allows us to better understand the physical properties of the AGN NLR gas. I will conclude showing some results from a recent analysis 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.

  9. AGN Triggering in Kpc-scale Separation Merging Galaxies

    NASA Astrophysics Data System (ADS)

    Comerford, Julia M.

    2017-01-01

    As supermassive black holes in galaxy mergers evolve from Mpc to mpc separations, the kpc-scale separations are pivotal for igniting AGN activity. At these separations the galaxy mergers drive central inflows of gas, which can trigger AGN activity in one or both supermassive black holes, in systems known as offset AGN and dual AGN, respectively. Offset and dual AGN are direct tracers of the connection between galaxy mass growth (via galaxy mergers) and supermassive black hole mass growth (via gas accretion). These systems are also the smallest separation supermassive black hole pairs that have been observationally confirmed, offering the last glimpse of supermassive black hole pair dynamics before gravitational wave emission dominates and drives the coalescence of the supermassive black holes. I will present multiwavelength approaches to building catalogs of offset AGN and dual AGN, and show the results of our observing campaigns with HST, Chandra, VLA, and Keck. Finally, I will discuss what our results show about whether galaxy mergers preferentially fuel the most luminous AGN, which supermassive black hole in a merger is more efficient at accreting gas, and where in a merger the AGN fueling occurs.

  10. AGN physics - A Chandra-Swift Census of AGN activity in Compact Groups

    NASA Astrophysics Data System (ADS)

    Tzanavaris, Panayiotis

    2012-09-01

    We present a missing link in the study of AGN activity in compact groups of galaxies. The level of this activity in compact groups remains controversial, but has only been studied with optical and infrared diagnostics. We present the first systematic study of 40 compact group galaxies in 9 groups, combining Chandra and Swift data, and providing the first X-ray/UV view of galactic nuclei in compact groups. Our results provide independent evidence that the level of AGN activity in compact groups is representative of their unique environment, which is distinct to that of rich clusters and the field.

  11. 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.

  12. AGN Luminosity and Stellar Age: Two Missing Ingredients for AGN Unification as Seen with iPTF Supernovae

    NASA Astrophysics Data System (ADS)

    Villarroel, Beatriz; Nyholm, Anders; Karlsson, Torgny; Comerón, Sébastien; Korn, Andreas J.; Sollerman, Jesper; Zackrisson, Erik

    2017-03-01

    Active galactic nuclei (AGNs) are extremely powerful cosmic objects, driven by accretion of hot gas upon super-massive black holes. The zoo of AGN classes is divided into two major groups, with Type-1 AGNs displaying broad Balmer emission lines and Type-2 narrow ones. For a long time it was believed that a Type-2 AGN is a Type-1 AGN viewed through a dusty kiloparsec-sized torus, but an emerging body of observations suggests more than just the viewing angle matters. Here we report significant differences in supernova (SN) counts and classes in the first study to date of SNe near Type-1 and Type-2 AGN host galaxies, using data from the intermediate Palomar Transient Factory, the Sloan Digital Sky Survey Data Release 7, and Galaxy Zoo. We detect many more SNe in Type-2 AGN hosts (size of effect ∼5.1σ) compared to Type-1 hosts, which shows that the two classes of AGN are located inside host galaxies with different properties. In addition, Type-1 and Type-2 AGNs that are dominated by star formation according to Wide-field Infrared Survey Explorer colors {m}W1-{m}W2< 0.5 and are matched in 22 μm absolute magnitude differ by a factor of ten in L[O iii] λ5007 luminosity, suggesting that when residing in similar types of host galaxies Type-1 AGNs are much more luminous. Our results demonstrate two more factors that play an important role in completing the current picture: the age of stellar populations and the AGN luminosity. This has immediate consequences for understanding the many AGN classes and galaxy evolution.

  13. 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

  14. X-ray and Ultraviolet Properties of AGNs in Nearby Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Baldassare, Vivienne F.; Reines, Amy E.; Gallo, Elena; Greene, Jenny E.

    2017-02-01

    We present new Chandra X-ray Observatory and Hubble Space Telescope observations of eight optically selected broad-line active galactic nucleus (AGN) candidates in nearby dwarf galaxies (z < 0.055). Including archival Chandra observations of three additional sources, our sample contains all 10 galaxies from Reines et al. (2013) with both broad Hα emission and narrow-line AGN ratios (six AGNs, four composites), as well as one low-metallicity dwarf galaxy with broad Hα and narrow-line ratios characteristic of star formation. All 11 galaxies are detected in X-rays. Nuclear X-ray luminosities range from L 0.5–7keV ≈ 5 × 1039 to 1 × 1042 ergs‑1. In all cases except for the star-forming galaxy, the nuclear X-ray luminosities are significantly higher than would be expected from X-ray binaries, providing strong confirmation that AGNs and composite dwarf galaxies do indeed host actively accreting black holes (BHs). Using our estimated BH masses (which range from ∼7 × 104 to 1 × 106 M ⊙), we find inferred Eddington fractions ranging from ∼0.1% to 50%, i.e., comparable to massive broad-line quasars at higher redshift. We use the HST imaging to determine the ratio of UV to X-ray emission for these AGNs, finding that they appear to be less X-ray luminous with respect to their UV emission than more massive quasars (i.e., α OX values an average of 0.36 lower than expected based on the relation between α OX and 2500 Å luminosity). Finally, we discuss our results in the context of different accretion models onto nuclear BHs.

  15. The Black Hole Mass - Pitch Angle Relation of Type I AGN In Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Schilling, Amanda; Jones, Logan; Hughes, John A.; Barrows, R. Scott; Kennefick, Julia D.

    2017-01-01

    A relationship between the mass of supermassive black holes, M, at the center of galaxies and the pitch angle, P, a measure of tightness of spiral arms, was recently reported by Berrier, et al. (2013 ApJ 769, 132) for late type galaxies. The relationship, established for a local sample, shows that spiral galaxies with tighter pitch angles host higher mass black holes. In this work, we explore the M-P relation for a sample of 50 low to moderate redshift (0.04AGN. These objects were selected from the SDSS quasar catalog and various studies involving HST imaging. Broad Hβ, Hα, and MgII and narrow [OIII]λ5007 emission lines were used with established mass scaling relations to estimate black-hole mass. Pitch angles were measured using a 2DFFT technique (Davis, et al., 2012 ApJS 199, 33). We find that the M-P relation for the higher redshift, AGN sample differs from that of the local sample and discuss the possibility of AGN feedback by looking at a proposed Fundamental Plane for late-type galaxies - a correlation between bulge mass, disk mass, and spiral-arm pitch angle (Davis, et al. 2015, ApJ 802, L13).

  16. 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.

  17. 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.; Croom, S. M.; 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.

  18. VizieR Online Data Catalog: X-ray variability of AGNs in Lockman Hole (Papadakis+, 2008)

    NASA Astrophysics Data System (ADS)

    Papadakis, I. E.; Chatzopoulos, E.; Athanasiadis, D.; Markowitz, A.; Georgantopoulos, I.

    2008-05-01

    We present the results from a detailed X-ray variability analysis of 66 AGN in the Lockman Hole, which have optical spectroscopic identifications. We compare, quantitatively, their variability properties with the properties of local AGN, and we study the "variability - luminosity" relation as a function of redshift, and the "variability - redshift" relation in two luminosity bins. We use archival data from the last 10 XMM-Newton observations of the Lockman Hole field to extract light curves in the rest frame, 2-10keV band. We use the "normalized excess variance" to quantify the variability amplitude. Using the latest results regarding the AGN power spectral shape and its dependence on black hole mass and accretion rate, we are able to compute model "variability - luminosity" curves, which we compare with the relations we observe. When we consider all the sources in our sample, we find that their variability amplitude decreases with increasing redshift and luminosity. (1 data file).

  19. AGN-halo Mass Assembly Connection in Galaxy Clusters: Investigation Using the Splashback Radius

    NASA Astrophysics Data System (ADS)

    McIntosh, Missy; More, Surhud; Silverman, John D.

    2017-01-01

    The splashback radius (also known as the last density caustic or the second turnaround radius) is a sharp dark matter halo edge that corresponds to the location of the first orbital apocenter of satellite galaxies after their infall. This definition of a halo boundary is more physical compared to the traditional definitions of halo boundaries which tend to be quite arbitrary. The splashback radius responds to the mass assembly history of clusters. For dark matter halos of the same mass, a large mass accretion rate results in a smaller splashback radius, since its deeper halo potential well has a closer apocenter. Using two cluster samples which had the same mass, but different splashback radii, we set out to check if the incidences of active galactic nuclei (AGN) in the member galaxies of these clusters are affected by their mass assembly history. Using SDSS spectroscopic data, we determined metallicity of galaxies and constructed a BPT diagram to classify each galaxy member in each cluster (Seyfert, Liner, Composite, etc.) and determined if an AGN was likely to be present. We compared the samples and determined that the rapidly assembling sample did have a larger AGN presence.

  20. 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.

  1. 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

  2. AGN Feedback in Clusters of Galaxies

    DTIC Science & Technology

    2010-01-01

    bubbles created by the radio lobes evacuating regions of the ICM vary widely from a few kpc (e.g. Abell 262 [21, 22]) to hundreds of kpc (e.g. MS0735.6...diameters of approximately 200 kpc . The total energy injection required to inflate the cavities and produce the ob- served shocks is 6 × 1061 erg...cluster center, and these are modeled as shocks in [32] based on the earlier 163 ksec dataset. These features are at 31 and 46 kpc from the AGN and the

  3. Obscured AGN With NuSTAR

    NASA Astrophysics Data System (ADS)

    Marinucci, Andrea; Bianchi, S.; Matt, G.; Balokovic, M.; Bauer, F. E.; Brandt W. N.; Gandhi, P.; Guainazzi, M.; Harrison, F.; Iwasawa, K.; Nicastro, F.; Puccetti, S.; Ricci, C.; Walton, D. J.; Stern, D.

    2016-10-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first orbiting telescope to focus high energy X-ray light above 10 keV. Compared to the previous generation of coded mask observatories, this change in technology provides NuSTAR with 10x sharper images and 100x improved sensitivityThe unprecedented spectral quality in the 3-80 keV band has provided unique information about the circumnuclear reflecting environment of AGNI will present and discuss results from the NuSTAR observations of nearby Obscured AGN in its first four years of science.

  4. Searching for Compton-thick AGN with INTEGRAL

    NASA Astrophysics Data System (ADS)

    Virani, S. N.; Treister, E.; Urry, C. M.; Maccarone, T.; Bird, T.; Beckmann, V.; Lira, P.; Coppi, P.; Uchiyama, Y.

    2005-12-01

    The 30 keV peak in the X-ray background strongly suggests there should be a large number of highly obscured AGN in the local universe. However, the exact number of these objects remains unknown, even though they could nearly double the space density of supermassive black holes. These Compton-thick AGN can be detected in the hard X-rays with INTEGRAL. As part of the current observing cycle, we were awarded 2 Msec to perform INTEGRAL imaging of the XMM-LSS field in order to find highly obscured AGN in the local Universe. In this paper, we present preliminary results for the ˜1 Ms of IBIS data obtained so far, including new hard X-ray detections of AGN. We also present the 20---200 keV spectra of the brightest AGN including the z<0.1 Seyfert galaxies NGC 788, NGC 1068, and NGC 1142.

  5. Galaxy And Mass Assembly (GAMA): the 325 MHz radio luminosity function of AGN and star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Prescott, Matthew; Mauch, T.; Jarvis, M. J.; McAlpine, K.; Smith, D. J. B.; Fine, S.; Johnston, R.; Hardcastle, M. J.; Baldry, I. K.; Brough, S.; Brown, M. J. I.; Bremer, M. N.; Driver, S. P.; Hopkins, A. M.; Kelvin, L. S.; Loveday, J.; Norberg, P.; Obreschkow, D.; Sadler, E. M.

    2016-03-01

    Measurement of the evolution of both active galactic nuclei (AGN) and star-formation in galaxies underpins our understanding of galaxy evolution over cosmic time. Radio continuum observations can provide key information on these two processes, in particular via the mechanical feedback produced by radio jets in AGN, and via an unbiased dust-independent measurement of star formation rates. In this paper, we determine radio luminosity functions at 325 MHz for a sample of AGN and star-forming galaxies by matching a 138 deg2 radio survey conducted with the Giant Metrewave Radio Telescope, with optical imaging and redshifts from the Galaxy And Mass Assembly survey. We find that the radio luminosity function at 325 MHz for star-forming galaxies closely follows that measured at 1.4 GHz. By fitting the AGN radio luminosity function out to z = 0.5 as a double power law, and parametrizing the evolution as Φ ∝ (1 + z)k, we find evolution parameters of k = 0.92 ± 0.95 assuming pure density evolution and k = 2.13 ± 1.96 assuming pure luminosity evolution. We find that the Low Excitation Radio Galaxies are the dominant population in space density at lower luminosities. Comparing our 325 MHz observations with radio continuum imaging at 1.4 GHz, we determine separate radio luminosity functions for steep- and flat-spectrum AGN, and show that the beamed population of flat-spectrum sources in our sample can be shifted in number density and luminosity to coincide with the unbeamed population of steep-spectrum sources, as is expected in the orientation-based unification of AGN.

  6. Inter-Stellar Medium Absorption Lines As Outflow Tracers - A Comparison Between AGNs And SFGs

    NASA Astrophysics Data System (ADS)

    Talia, Margherita; Cimatti, A.; Brusa, M.

    2016-10-01

    To reproduce the properties of galaxies in the local Universe, as well as the scaling relations between host galaxies and black holes properties, many galaxy formation models invoke the presence of fast and energetic winds extending over galaxy scales. These massive gas outflows can be powered either by star-formation (SF) or AGN activity, though the relative dominance and efficiency of the different mechanisms is not yet fully understoodIn the last decade much effort has been put in the search for observational evidence of such phenomena, especially at the peak of both SF and AGN activity through cosmic time (1AGNs and their host galaxies. Spectroscopy at different wavelengths is the most powerful tool to find and investigate outflows. Blue-shifted inter-stellar medium (ISM) absorption lines in the UV regime, as well as broad, blue-shifted profiles in optical emission lines have been observed in galaxies at all redshifts and are usually interpreted as evidence of fast material moving towards our line of sight. More recently, especially thanks to new facilities like ALMA, outflows are being observed also in neutral and molecular gasIn order to study the differences and possible synergy between the two main driving outflow mechanisms (AGN or SF activity) and to understand the role that outflows might play in SF quenching and galaxy evolution, we collected a large sample of AGNs and SFGs at z>1.7 from large optical spectroscopic surveys (zCOSMOS, VUDS, ESO public surveys), complemented with HST imaging, X-ray (Chandra) and IR data. The richness of available data for our sample allowed us to map a large portion of the physical parameters space. We concentrated our analysis on the ISM absorption lines in the rest-frame UV wavelength range. Through stacking tecniques we studied the relation between such lines and AGN and SFG properties. I will present our results (Talia et al

  7. 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.

  8. Improving Calibration of the MBH-σ* Relation for AGN with the BRAVE Program

    NASA Astrophysics Data System (ADS)

    Batiste, Merida; Bentz, Misty C.; Manne-Nicholas, Emily; Raimundo, Sandra I.; Onken, Christopher A.; Vestergaard, Marianne; Bershady, Matthew A.

    2017-01-01

    The MBH - σ* relation for AGN, which relates the mass of the central supermassive black hole (MBH) to the bulge stellar velocity dispersion (σ*) of the host galaxy, is a powerful tool for studying the evolution of structure across cosmic time. Accurate calibration of this relation is essential, and much effort has been put into improving MBH determinations with this in mind. However calibration remains difficult because many nearby AGN with secure MBH determinations are hosted by late-type galaxies, with significant kinematic substructure such as bars, disks and rings. Kinematic substructure is known to contaminate and bias σ* determinations from long-slit and single aperture spectroscopy, ultimately limiting the utility of the MBH - σ* relation, and hampering efforts to investigate morphological dependencies. Integral-field spectroscopy (IFS) can be used to map the two dimensional kinematics, providing a method for measuring σ* absent some of the biases inherent in other methods, and giving a more complete picture of the spatial variations in the dynamics. We present the first set of results from the BRAVE program, the long-term goal of which is to use IFS to more accurately determine σ* for the calibrating sample of reverberation-mapped AGN. We present IFS kinematic maps for the sample of galaxies we have so far observed, which show clearly how spatial variation can impact σ* determinations from long-slit spectroscopy. We present a new fit to the MBH - σ* relation for the sample of 16 reverberation-mapped AGN for which we currently have σ* determinations from IFS, as well as a new determination of the virial scaling factor, f, for use with reverberation-mapping.

  9. 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.

  10. Extremely efficient Zevatron in rotating AGN magnetospheres

    NASA Astrophysics Data System (ADS)

    Osmanov, Z.; Mahajan, S.; Machabeli, G.; Chkheidze, N.

    2014-12-01

    A novel model of particle acceleration in the magnetospheres of rotating active galactic nuclei (AGN) is constructed. The particle energies may be boosted up to 1021 eV in a two-step mechanism: in the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. In the second stage, the electrostatic energy is transferred to particle kinetic energy via Landau damping made possible by rapid `Langmuir collapse'. The time-scale for parametric pumping of Langmuir waves turns out to be small compared to the kinematic time-scale, indicating high efficiency of the first process. The second process of `Langmuir collapse' - the creation of caverns or low-density regions - also happens rapidly for the characteristic parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate conditions for transferring electric energy to boost up already high particle energies to much higher values. It is further shown that various energy loss mechanism are relatively weak, and do not impose any significant constraints on maximum achievable energies.

  11. Extending ROSAT Light Curves of Ecliptic Pole AGN Formation and Galaxy Evolution

    NASA Technical Reports Server (NTRS)

    Malkan, Matthew A.

    1997-01-01

    In collaboration with UCLA graduate student Fred Baganoff, Professor Malkan has obtained the longest continuous light curves ever available for a large sample (# = 60) of active galactic nuclei. This was accomplished by using the ROSATAII-Sky Survey, which covered the ecliptic pole regions once every 9O-minute orbit. Using this Astrophysics Data Processing grant from NASA, we extended these light curves by combining the RASS data with pointed observations over the next several years of operation of the ROSAT PSPC. This lengthens the baselines of about half of the light curves from a few months up to a few years. The proportion of AGN showing variability increases substantially with this improvement. In fact most AGN in this representative sample are now shown to be significantly variable in the X-rays. We are also able to say something about the amplitudes of variability on timescales from days to years, with more detail than previously has been possible. We have also identified some dependence of the X-ray variability properties on a) the luminosity of the AGN; and b) The presence of a "Blazar" nucleus. By extending the ROSAT light curves, we are also able to learn more about the correlation of X-ray and optical emission on longer time-scales. It appears to be very weak, at best.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Planck's Dusty GEMS: Measuring the AGN Contribution in the Brightest z 3 Star-Forming Galaxies in the Sky

    NASA Astrophysics Data System (ADS)

    Chary, Ranga-Ram

    Hyperluminous (>1E13 Lsun) infrared galaxies detected at submillimeter wavelengths are among the most intense, star-forming galaxies in the Universe. Although they show signs of AGN activity in the X-rays and the mid-infrared, it is generally thought that their bolometric luminosity, most of which is emitted in the far-infrared, is dominated by star-formation and not by the AGN. Here, we propose to measure the AGN contribution in a population of high redshift (z 3) submillimeter galaxies detected through the Planck all sky survey which have been greatly amplified through gravitational lensing by a foreground galaxy. The SOFIA data bridge the gap in wavelength coverage that exists between the WISE 22 micron and Herschel 250 micron data - this is crucial for sampling the hot dust emission from a buried AGN and deriving robust bolometric luminosities. Our observations will also characterize the multiple components of thermal dust emission to critically assess the canonical view that high redshift starbursts appear to show a limited range of spectral energy distribution (SED) shapes in the far-infrared that is distinct from the SED of main-sequence star-forming galaxies. Since these SEDs have been the benchmark for characterizing the unlensed star-forming, submillimeter galaxy (SMG) population, the proposed observations will have an impact not just on our target sample but on the derived properties of the SMG population as a whole, such as their star-formation rate and gas/dust mass.

  19. Short time-scale AGN X-ray variability with EXOSAT: black hole mass and normalized variability amplitude

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.

    2013-03-01

    The old EXOSAT medium energy measurements of high-frequency (HF) active galactic nuclei (AGN) power spectral normalization are re-examined in the light of accurate black hole mass determinations which were not available when these data were first published by Green et al. It is found that the normalized variability amplitude (NVA), measured directly from the power spectrum, is proportional to Mβ, where β ˜ -0.54 ± 0.08. As NVA is the square root of the power, these observations show that the normalization of the HF power spectrum for this sample of AGN varies very close to inversely with black hole mass. Almost the same value of β is obtained whether the quasar 3C 273 is included in the sample or not, suggesting that the same process that drives X-ray variability in Seyfert galaxies applies also to 3C 273. These observations support the work of Gierliński et al. who show that an almost exactly linear anticorrelation is required if the normalizations of the HF power spectra of AGN and X-ray binary systems are to scale similarly. These observations are also consistent with a number of studies showing that the short time-scale variance of AGN X-ray light curves varies approximately inversely with mass.

  20. Accretion-ejection models for AGN jets

    NASA Astrophysics Data System (ADS)

    Zanni, C.

    2008-10-01

    It is likely that jets from Active Galactic Nuclei derive their energy from accretion onto the central black hole. It is actually possible to fuel the jets by extracting energy and angular momentum from the accretion disk and/or the rotating black hole via the action of large-scale magnetic fields. In this talk I will first present results of analytical and numerical models of the launching process of jets from magnetized accretion disks: I will show that, although a sizeable fraction of the accretion power goes into the jets, these outflows are presumably only mildly relativistic. In the second place, I will therefore suggest that the strongly relativistic components observed at the VLBI scales are accelerated in the innermost parts of the AGNs by Blandford-Znajek and/or Compton-rocket processes. Nonetheless, the non-relativistic disk-wind is needed to collimate the relativistic component and to reproduce the total power of extragalactic jets.

  1. AGN warm absorption with the ATHENA

    NASA Astrophysics Data System (ADS)

    Różańska, Agata; Gronkiewicz, Dominik; Hryniewicz, Krzysztof; Adhikari, Tek Prasad; Rataj, Mirosław; Skup, Konrad

    2016-06-01

    X-ray astronomy requires satellites to make progress in searching the distribution of hot matter in the Universe. Approximately 15 years period of time is needed for full construction of the flight instrument from the mission concept up to the launch. A new generation X-ray telescope ATHENA (the Advanced Telescope for High Energy Astrophysics) was approved by European Space Agency as a large mission with a launch foreseen in 2028. In this paper we show how microcalorimeter on the board of ATHENA will help us to study warm absorption observed in active galactic nuclei (AGN). We show that future observations will allow us to identify hundreds of lines from highly ionized elements and to measure Galactic warm absorption with very high precision.

  2. Neutrino radiation of the AGN black holes

    NASA Astrophysics Data System (ADS)

    Ter-Kazarian, G.; Shidhani, S.; Sargsyan, L.

    2007-07-01

    In the framework of ‘microscopic’ theory of black holes (J. Phys. Soc. Jpn. Suppl. B 70, 84, 2001; Astrophys. USSR 4, 659, 1996; 35, 335, 1991, 33, 143, 1990, 31, 345, 1989a; Astrophys. Space Sci. 1, 1992; Dokl. Akad. Nauk USSR 309, 97, 1989b), and references therein, we address the ‘pre-radiation time’ (PRT) of neutrinos from black holes, which implies the lapse of time from black hole’s birth till radiation of an extremely high energy neutrinos. For post-PRT lifetime, the black hole no longer holds as a region of spacetime that cannot communicate with the external universe. We study main features of spherical accretion onto central BH and infer a mass accretion rate onto it, and, further, calculate the resulting PRT versus bolometric luminosity due to accretion onto black hole. We estimate the PRTs of AGN black holes, with the well-determined masses and bolometric luminosities, collected from the literature by Woo Jong-Hak and Urry (Astrophys. J. 579, 530, 2002) on which this paper is partially based. The simulations for the black holes of masses M BH ≃(1.1ṡ106 ÷4.2ṡ109) M ⊙ give the values of PRTs varying in the range of about T BH ≃(4.3ṡ105 ÷5.6ṡ1011) yr. The derived PRTs for the 60 AGN black holes are longer than the age of the universe (˜13.7 Gyr) favored today. At present, some of remaining 174 BHs may radiate neutrinos. However, these results would be underestimated if the reservoir of gas for accretion in the galaxy center is quite modest, and no obvious way to feed the BHs with substantial accretion.

  3. The LBT/WISSH quasar survey: revealing powerful winds in the most luminous AGN

    NASA Astrophysics Data System (ADS)

    Vietri, Giustina

    2017-01-01

    The systematic, multi-frequency investigation of hyper-luminous quasars shining at the golden epoch of AGN activity offers the unique opportunity of studying the power and the effect of AGN feedback at its extreme.The WISE/SDSS selected hyper-luminous (WISSH) quasar survey is an extensive multi-band observing program (from millimeter wavelengths to hard X rays) designed to accurately probe the role of nuclear activity in SMBH-galaxy self-regulated growth via extended outflows.Our on-going project aims at constraining both AGN and host galaxy ISM and star-formation properties in a large sample of ~ 90 broad-line quasars at the brightest end of the AGN luminosity function (L_bol > 1e14 L_sun), and at the peak of their number density (z ~ 2.5 - 3.5).I will review the most important results of the near-IR spectroscopic follow-up of WISSH quasars (available for ~40% of the total sample) performed with the LUCI at LBT. These observations were carried out to obtain a reliable Hbeta-based estimate of the SMBH masses and a census of the ionized outflows in these hyper-luminous quasars.We found that WISSH AGN are typically powered by highly accreting (0.3-3 Ledd), ten billion solar masses SMBHs, demonstrating that WISSH provides a simple and valuable tool to complete the census of the extreme SMBH population in the universe.We also succeeded in discovering [OIII] emission lines with a broad, skewed profile and exceptional luminosities (> 6e44 erg/s), tracing very powerful ionized outflows (up to ~4% of L_bol) in ~30% of the sample.Remarkably, the remaining 70% of quasars lacks [OIII] emission but shows strong winds traced by 3,000-8,000 km/s blueshifts of the high-ionization (CIV) with respect to low-ionization (Hbeta) broad emission lines, revealing strong radiatively driven winds that dominate the BLR kinematics.I will discuss the possible origins of this intriguing dichotomy which involves fundamental parameters such as bolometric luminosity, SMBH mass, Eddington ratio

  4. 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 .

  5. VizieR Online Data Catalog: IR spectroscopy of AGN & starbursts (Samsonyan+, 2016)

    NASA Astrophysics Data System (ADS)

    Samsonyan, A.; Weedman, D.; Lebouteiller, V.; Barry, D.; Sargsyan, L.

    2016-10-01

    A sample of 379 extragalactic sources is presented that has mid-infrared, high-resolution spectroscopy from the Spitzer Infrared Spectrograph (IRS) and also spectroscopy of the [CII]158μm line from the Herschel Photodetector Array Camera and Spectrometer (PACS). The emission line profiles of [NeII]12.81μm, [NeIII]15.55μm, and [CII]158μm are presented, and intrinsic line widths are determined (full width half maximum of Gaussian profiles after instrumental correction). All line profiles, together with overlays comparing the positions of PACS and IRS observations, are made available in the Cornell Atlas of Spitzer IRS Sources (CASSIS). Sources are classified from active galactic nucleus (AGN) to starburst based on equivalent widths of the 6.2μm polycyclic aromatic hydrocarbon feature. It is found that intrinsic line widths do not change among classifications for [CII], with median widths of 207km/s for AGNs, 248km/s for composites, and 233km/s for starbursts. The [NeII] line widths also do not change with classification, but [NeIII] lines are progressively broader from starburst to AGN. A few objects with unusually broad lines or unusual redshift differences in any feature are identified. (1 data file).

  6. 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.

  7. 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.

  8. Modelling reverberation mapping data - II. Dynamical modelling of the Lick AGN Monitoring Project 2008 data set

    NASA Astrophysics Data System (ADS)

    Pancoast, Anna; Brewer, Brendon J.; Treu, Tommaso; Park, Daeseong; Barth, Aaron J.; Bentz, Misty C.; Woo, Jong-Hak

    2014-12-01

    We present dynamical modelling of the broad-line region (BLR) for a sample of five Seyfert 1 galaxies using reverberation mapping data taken by the Lick AGN Monitoring Project in 2008. By modelling the AGN continuum light curve and Hβ line profiles directly, we are able to constrain the geometry and kinematics of the BLR and make a measurement of the black hole mass that does not depend upon the virial factor, f, needed in traditional reverberation mapping analysis. We find that the geometry of the BLR is generally a thick disc viewed close to face-on. While the Hβ emission is found to come preferentially from the far side of the BLR, the mean size of the BLR is consistent with the lags measured with cross-correlation analysis. The BLR kinematics are found to be consistent with either inflowing motions or elliptical orbits, often with some combination of the two. We measure black hole masses of log _{10}(M_ BH/M_{odot })=6.62^{+0.10}_{-0.13} for Arp 151, 7.42^{+0.26}_{-0.27} for Mrk 1310, 7.59^{+0.24}_{-0.21} for NGC 5548, 6.37^{+0.21}_{-0.16} for NGC 6814, and 6.99^{+0.32}_{-0.25} for SBS 1116+583A. The f factors measured individually for each AGN are found to correlate with inclination angle, although not with M BH, L5100, or FWHM/σ of the emission line profile.

  9. 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.

  10. Star Formation and AGN Activity in Luminous and Ultraluminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Kartaltepe, Jeyhan

    2015-08-01

    In the local universe, Ultraluminous Infrared Galaxies (ULIRGs, L_IR > 10^12 L⊙) are all interacting and merging systems. We explore the evolution of the morphological and nuclear properties of (U)LIRGs over cosmic time using a large sample of galaxies from Her- schel observations of the CANDELS fields (including GOODS, COSMOS, and UDS). In particular, we investigate whether the role of galaxy mergers has changed between z ˜ 2 and now using the extensive visual classification catalogs produced by the CANDELS team. The combination of a selection from Herschel, near the peak of IR emission, and rest-frame optical morphologies from CANDELS, provides the ideal comparison to nearby (U)LIRGs. We also use rest-frame optical emission line diagnostics, X-ray luminosity, and MIR colors to separate AGN from star-formation dominated galaxies. We then study the how role of galaxy mergers and the presence of AGN activity correspond to the galaxy’s position in the star formation rate - stellar mass plane. Are galaxies that have specific star formation rates elevated above the main sequence more likely to be mergers? We investigate how AGN identified with different methods correspond to different morphologies and merger stages as well as position on the star formation rate - stellar mass plane.

  11. [Ultra] luminous infrared galaxies selected at 90 μm in the AKARI deep field: a study of AGN types contributing to their infrared emission

    NASA Astrophysics Data System (ADS)

    Małek, K.; Bankowicz, M.; Pollo, A.; Buat, V.; Takeuchi, T. T.; Burgarella, D.; Goto, T.; Malkan, M.; Matsuhara, H.

    2017-01-01

    Aims: The aim of this work is to characterize physical properties of ultra luminous infrared galaxies (ULIRGs) and luminous infrared galaxies (LIRGs) detected in the far-infrared (FIR) 90 μm band in the AKARI Deep Field-South (ADF-S) survey. In particular, we want to estimate the active galactic nucleus (AGN) contribution to the LIRGs and ULIRGs' infrared emission and which types of AGNs are related to their activity. Methods: We examined 69 galaxies at redshift ≥0.05 detected at 90 μm by the AKARI satellite in the ADF-S, with optical counterparts and spectral coverage from the ultraviolet to the FIR. We used two independent spectral energy distribution fitting codes: one fitting the SED from FIR to FUV (CIGALE) (we use the results from CIGALE as a reference) and gray-body + power spectrum fit for the infrared part of the spectra (CMCIRSED) in order to identify a subsample of ULIRGs and LIRGs, and to estimate their properties. Results: Based on the CIGALE SED fitting, we have found that LIRGs and ULIRGs selected at the 90 μm AKARI band compose 56% of our sample (we found 17 ULIRGs and 22 LIRGs, spanning over the redshift range 0.06 samples selected at infrared wavelengths. We have detected a significant AGN contribution to the mid-infrared luminosity for 63% of LIRGs and ULIRGs. Our LIRGs contain Type 1, Type 2, and intermediate types of AGN, whereas for ULIRGs, a majority (more than 50%) of AGN emission originates from Type 2 AGNs. The temperature-luminosity and temperature-mass relations for the dust component of ADF-S LIRGs and ULIRGs indicate that these relations are shaped by the dust mass and not by the increased dust heating. Conclusions: We conclude that LIRGs contain Type 1, Type 2, and intermediate types of AGNs, with an AGN contribution to the mid infrared emission at the median level of 13 ± 3

  12. The Lick AGN Monitoring Project: Recalibrating Single-epoch Virial Black Hole Mass Estimates

    NASA Astrophysics Data System (ADS)

    Park, Daeseong; Woo, Jong-Hak; Treu, Tommaso; Barth, Aaron J.; Bentz, Misty C.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor; Greene, Jenny E.; Malkan, Matthew A.; Walsh, Jonelle

    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 <108 M ⊙. By decomposing the spectra into their AGNs and stellar components, we study the variability of the SE Hβ line width (full width at half-maximum intensity, FWHMHβ or dispersion, σHβ) and of the AGN continuum luminosity at 5100 Å (L 5100). From the distribution of the "virial products" (vprop FWHMHβ 2 L 0.5 5100 or σHβ 2 L 0.5 5100) measured from SE spectra, we estimate the uncertainty due to the combined variability as ~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 ~0.46 dex (factor of ~3). By comparing the Hβ line profile of the SE, mean, and root-mean-square (rms) spectra, we find that the Hβ line is broader in the mean (and SE) spectra than in the rms spectra by ~0.1 dex (25%) for our sample with FWHMHβ <3000 km s-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 Hβ line profile, we introduce a line-width dependent virial factor, resulting in a recalibration of SE BH mass estimators for low-mass AGNs.

  13. Revisiting the Structure and Spectrum of the Magnetic-reconnection-heated Corona in Luminous AGNs

    NASA Astrophysics Data System (ADS)

    Liu, J. Y.; Qiao, E. L.; Liu, B. F.

    2016-12-01

    It is believed that the hard X-ray emission in the luminous active galactic nuclei (AGNs) is from the hot corona above the cool accretion disk. However, the formation of the corona is still debated. Liu et al. investigated the spectrum of the corona heated by the reconnection of the magnetic field generated by dynamo action in the thin disk and emerging into the corona as a result of buoyancy instability. In the present paper, we improve this model to interpret the observed relation of the hard X-ray spectrum becoming softer at higher accretion rate in luminous AGNs. The magnetic field is characterized by {β }0, i.e., the ratio of the sum of gas pressure and radiation pressure to the magnetic pressure in the disk ({β }0=({P}g,d+{P}r,d)/{P}B). Besides, both the intrinsic disk photons and reprocessed photons by the disk are included as the seed photons for inverse Compton scattering. These improvements are crucial for investigating the effect of magnetic field on the accretion disk corona when it is not clear whether the radiation pressure or gas pressure dominates in the thin disk. We change the value of {β }0 in order to constrain the magnetic field in the accretion disk in luminous AGNs. We find that the energy fraction released in the corona (f) gradually increases with the decrease of {β }0 for the same accretion rate. When {β }0 decreases to less than 50, the structure and spectrum of the disk corona are independent of accretion rate, which is similar to the hard spectrum found in Liu et al. Comparing with the observational results of the hard X-ray bolometric correction factor in a sample of luminous AGNs, we suggest that the value of {β }0 is about 100-200 for α = 0.3, and the energy fraction f should be larger than 30% for hard X-ray emission.

  14. AGN STORM: A Leap Forward In Reverberation Mapping

    NASA Astrophysics Data System (ADS)

    Dalla Bontà, Elena; AGN STORM Team

    2016-10-01

    Reverberation mapping is a tomographic technique that can be used to determine the structure and kinematics of the broad- line emitting region at the center of active galactic nuclei. By-products of these investigations are the masses of the central black holes and information about the structure of the accretion disk. I will show some of the most recent results from the AGN Space Telescope and Optical Reverberation Mapping (AGN STORM) project, which was built around 180 daily observations of the bright Seyfert 1 galaxy NGC 5548 with the Cosmic Origins Spectrograph on Hubble Space Telescope. AGN STORM included observations made with Swift, XMM, and several ground-based telescopes, including the 1.22-m telescope at Asiago Observatory. Elena Dalla Bonta` on behalf of the AGN STORM Team.

  15. 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.

  16. 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.

  17. Hard X-Ray-selected AGNs in Low-mass Galaxies from the NuSTAR Serendipitous Survey

    NASA Astrophysics Data System (ADS)

    Chen, C.-T. J.; Brandt, W. N.; Reines, A. E.; Lansbury, G.; Stern, D.; Alexander, D. M.; Bauer, F.; Del Moro, A.; Gandhi, P.; Harrison, F. A.; Hickox, R. C.; Koss, M. J.; Lanz, L.; Luo, B.; Mullaney, J. R.; Ricci, C.; Trump, J. R.

    2017-03-01

    We present a sample of 10 low-mass active galactic nuclei (AGNs) selected from the 40-month Nuclear Spectroscopic Telescope Array (NuSTAR) serendipitous survey. The sample is selected to have robust NuSTAR detections at 3{--}24 {keV}, to be at z< 0.3, and to have optical r-band magnitudes at least 0.5 mag fainter than an {L}\\star galaxy at its redshift. The median values of absolute magnitude, stellar mass, and 2–10 X-ray luminosity of our sample are < {M}r> =-20.03, < {M}\\star > =4.6× {10}9 {M}ȯ , and < {L}2-10{keV}> =3.1× {10}42 erg s‑1, respectively. Five objects have detectable broad Hα emission in their optical spectra, indicating black hole masses of (1.1{--}10.4)× {10}6 {M}ȯ . We find that {30}-10+17 % of the galaxies in our sample do not show AGN-like optical narrow emission lines, and one of the 10 galaxies in our sample, J115851+4243.2, shows evidence for heavy X-ray absorption. This result implies that a non-negligible fraction of low-mass galaxies might harbor accreting massive black holes that are missed by optical spectroscopic surveys and < 10 {keV} X-ray surveys. The mid-IR colors of our sample also indicate that these optically normal low-mass AGNs cannot be efficiently identified with typical AGN selection criteria based on Wide Field Infrared Survey Explorer colors. While the hard (> 10 keV) X-ray-selected low-mass AGN sample size is still limited, our results show that sensitive NuSTAR observations are capable of probing faint hard X-ray emission originating from the nuclei of low-mass galaxies out to moderate redshift (z< 0.3), thus providing a critical step in understanding AGN demographics in low-mass galaxies.

  18. 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

  19. 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

  20. Improved characterization of intranight optical variability of prominent AGN classes

    NASA Astrophysics Data System (ADS)

    Goyal, Arti; Gopal-Krishna, Wiita, Paul J.; Stalin, C. S.; Sagar, Ram

    2013-10-01

    The incidence of intranight optical variability (INOV) is known to differ significantly among different classes of powerful active galactic nuclei (AGN). A number of statistical methods have been employed in the literature for testing the presence of INOV in the light curves, sometimes leading to discordant results. In this paper, we compare the INOV characteristics of six prominent classes of AGN, as evaluated using three commonly used statistical tests, namely the χ2-test, the modified C-test and the F-test, which has recently begun to gain popularity. The AGN classes considered are: radio-quiet quasars, radio-intermediate quasars, lobe-dominated quasars, low optical polarization core-dominated quasars, high optical polarization core-dominated quasars and TeV blazars. Our analysis is based on a large body of AGN monitoring data, involving 262 sessions of intranight monitoring of a total 77 AGN, using 1-2 m class optical telescopes located in India. In order to compare the usefulness of the statistical tests, we have also subjected them to a `sanity check' by comparing the number of false positives yielded by each test with the corresponding statistical prediction. The present analysis is intended to serve as a benchmark for future INOV studies of AGN of different classes.

  1. 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.

  2. 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.

  3. Unwrapping the X-ray Spectra of AGN

    NASA Astrophysics Data System (ADS)

    Reynolds, C.

    2015-07-01

    Active galactic nuclei (AGN) are complex phenomena. At the heart of an AGN is a relativistic accretion disk around the spinning supermassive black hole with a compact, probably pair-regulated, X-ray corona. On larger scales, the outer accretion disk and molecular torus act as the reservoirs of gas for the continuing AGN activity. And on all scales from the black hole outwards, powerful winds (and sometimes jets) are seen and can dominate the source energetics. As I shall review in this talk, each of these components imprints its own characteristic signature into the (time-variable) X-ray spectrum of the AGN. I shall then touch upon a few contemporary topics : (i) the use of new spectral timing techniques for aiding in the decomposition of the spectrum and for probing the geometry of the AGN central engine, (ii) the determination of supermassive black hole spin, (iii) direct confirmation of quasar-mode feedback in some luminous systems. The prospect of AGN observations with Astro-H will be discussed.

  4. 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.; Arribas, M. Paz; 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.

    2014-03-01

    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).

  5. 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.

  6. VizieR Online Data Catalog: SPIRE observations of Herschel-BAT sample (Shimizu+, 2016)

    NASA Astrophysics Data System (ADS)

    Shimizu, T. T.; Melendez, M.; Mushotzky, R. F.; Koss, M. J.; Barger, A. J.; Cowie, L. L.

    2016-09-01

    We selected our sample of 313 AGN from the 58 month Swift/BAT Catalogue (https://swift.gsfc.nasa.gov/results/bs58mon) (Baumgartner et al., 2012, in prep.), imposing a redshift cutoff of z<0.05. All different types of AGN were chosen only excluding Blazars/BL Lac objects which most likely introduce complicated beaming effects. To determine their AGN type, for 252 sources we used the classifications from the BAT AGN Spectroscopic Survey (Koss et al., in preparation) which compiled and analysed optical spectra for the Swift/BAT 70 month catalogue (Berney et al., 2015MNRAS.454.3622B). (2 data files).

  7. Characterizing the far-infrared properties of distant X-ray detected AGNs: evidence for evolution in the infrared-X-ray luminosity ratio

    NASA Astrophysics Data System (ADS)

    Mullaney, J. R.; Alexander, D. M.; Huynh, M.; Goulding, A. D.; Frayer, D.

    2010-01-01

    We investigate the far-infrared (FIR) properties of X-ray sources detected in the Chandra Deep Field-South (CDF-S) survey using the ultradeep 70 and 24 μm Spitzer observations taken in this field. Since only 30 (i.e. ~10 per cent) of the 266 X-ray sources in the region of the 70 μm observations are detected at 70 μm, we rely on stacking analyses of the 70 μm data to characterize the average 70 μm properties of the X-ray sources as a function of redshift, X-ray luminosity and X-ray absorption. Using Spitzer-IRS data of the Swift-Burst Alert Telescope (BAT) sample of z ~ 0 active galactic nuclei (AGNs), we show that the 70/24 μm flux ratio can distinguish between AGN-dominated and starburst-dominated systems out to z ~ 1.5. Among the X-ray sources detected at 70 μm, we note a large scatter in the observed 70/24 μm flux ratios, spanning almost a factor of 10 at similar redshifts, irrespective of object classification, suggesting a range of AGN:starburst ratios. From stacking analyses we find that the average observed 70/24 μm flux ratios of AGNs out to an average redshift of 1.5 are similar to z ~ 0 AGNs with similar X-ray luminosities (LX = 1042-44ergs-1) and absorbing column densities (NH <= 1023cm-2). Furthermore, both high-redshift and z ~ 0 AGNs follow the same tendency towards warmer 70/24 μm colours with increasing X-ray luminosity (LX). From analyses of the Swift-BAT sample of z ~ 0 AGNs, we note that the 70 μm flux can be used to determine the IR (8-1000 μm) luminosities of high-redshift AGNs. We use this information to show that LX = 1042-43ergs-1 AGNs at high redshifts (z = 1-2) have IR to X-ray luminosity ratios (LIR/LX) that are, on average, 4.7+10.2-2.0 and 12.7+7.1-2.6 times higher than AGNs with similar X-ray luminosities at z = 0.5-1 and ~0, respectively. By comparison, we find that the LIR/LX ratios of LX = 1043-44ergs-1 AGNs remain largely unchanged across this same redshift interval. We explore the consequences that these results may

  8. SUPERNOVAE AND AGN DRIVEN GALACTIC OUTFLOWS

    SciTech Connect

    Sharma, Mahavir; Nath, Biman B. E-mail: biman@rri.res.in

    2013-01-20

    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{sub *}{approx}( E-dot / 2 M-dot ){sup 1/2} describes the effect of starburst activity, with E-dot and M-dot as energy and mass injection rate in a central region of radius R; (2) v {sub .} {approx} (GM {sub .}/2R){sup 1/2} for the effect of a central black hole of mass M {sub .} on gas at distance R; and (3) v{sub s}=(GM{sub h} / 2Cr{sub s}){sup 1/2}, which is closely related to the circular speed (v{sub c} ) for an NFW halo, where r{sub s} 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 {sup 2} {sub *} + 6({Gamma} - 1)v {sub .} {sup 2} - 4v {sup 2} {sub s}){sup 1/2}, where {Gamma} 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 10{sup 11.5} M {sub Sun} {<=} M{sub h} {<=} 10{sup 12.5} M {sub Sun} 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 {approx}400-1000 km s{sup -1}, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds {approx}> 1000 km s{sup -1}. We also find that the ratio [2v {sup 2} {sub *} - (1 - {Gamma})v {sub .} {sup 2}]/v {sup 2} {sub c} dictates the amount of gas lost through winds. Used in conjunction with

  9. 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.

  10. Bulgeless Galaxies Hosting 107 M⊙ AGN in Galaxy Zoo: The Growth of Black Holes via Secular Processes

    NASA Astrophysics Data System (ADS)

    Simmons, Brooke; Lintott, C. J.; Schawinski, K.; Moran, E. C.; Han, A.; Kaviraj, S.; Masters, K. L.; Urry, C. M.; Willett, K.; Bamford, S. P.; Nichol, R.

    2013-01-01

    The growth of supermassive black holes (SMBHs) appears to proceed via multiple pathways including mergers and secular processes, but these are difficult to disentangle for most galaxies given their complex evolutionary histories. In order to understand the effects of secular galaxy evolution on black hole growth, we require a sample of active galactic nuclei (AGN) in galaxies with a calm formation history free of significant mergers, a population that heretofore has been difficult to locate. Here we present a sample of 13 AGN in massive galaxies lacking the classical bulges believed inevitably to result from mergers; they also either lack or have extremely small pseudobulges, meaning they have had very calm accretion histories. This is the largest sample to date of massive, bulgeless AGN host galaxies selected without any direct restriction on the SMBH mass. The broad-line objects in the sample have black hole masses of 106-7 M⊙ Eddington arguments imply similar masses for the rest of the sample, meaning these black holes have grown substantially in the absence of mergers or other bulge-building processes such as violent disk instabilities. The black hole masses are systematically higher than expected from established bulge-black hole relations. However, these systems may be consistent with the correlation between black hole mass and total stellar mass. We discuss these results in the context of other studies and consider the implication that the details of stellar galaxy evolution and dynamics may not be fundamental to the co-evolution of galaxies and black holes.

  11. VizieR Online Data Catalog: Optically bright AGN in ROSAT-FSC (Veron-Cetty+, 2004)

    NASA Astrophysics Data System (ADS)

    Veron-Cetty, M.-P.; Balayan, S. K.; Mickaelian, A. M.; Mujica, R.; Chavushyan, V.; Hakopian, S. A.; Engels, D.; Veron, P.; Zickgraf, F.-J.; Voges, W.; Xu, D.-W.

    2004-02-01

    To build a large, optically bright, X-ray selected AGN sample we have correlated the ROSAT-FSC () catalogue of X-ray sources with the USNO () catalogue limited to objects brighter than O=16.5 and then with the APS () database. Each of the 3212 coincidences was classified using the slitless Hamburg spectra. 493 objects were found to be extended and 2719 starlike. Using both the extended objects and the galaxies known from published catalogues we built up a sample of 185 galaxies with O(APS)<17.0mag, which are high-probability counterparts of RASS-FSC X-ray sources. 130 galaxies have a redshift from the literature and for another 34 we obtained new spectra. The fraction of Seyfert galaxies in this sample is 20%. To select a corresponding sample of 144 high-probability counterparts among the starlike sources we searched for very blue objects in an APS-based color-magnitude diagram. Forty-one were already known AGN and for another 91 objects we obtained new spectra, yielding 42 new AGN, increasing their number in the sample to 83. This confirms that surveys of bright QSOs are still significantly incomplete. On the other hand we find that, at a flux limit of 0.02ct/s and at this magnitude, only 40% of all QSOs are detected by ROSAT. (3 data files).

  12. Star-forming galaxies versus low- and high-excitation radio AGN in the VLA-COSMOS 3GHz Large Project

    NASA Astrophysics Data System (ADS)

    Baran, Nikola; Smolcic, Vernesa; Delvecchio, Ivan; Novak, Mladen; Delhaize, Jacinta; Laigle, Clotilde; Ilbert, Olivier; (Vla-)Cosmos Collaboration

    2016-08-01

    We study the composition of the faint radio population selected from the VLA-COSMOS 3GHz Large Project, a radio continuum survey performed at 10 cm wavelength. The survey covers the full 2 square degree COSMOS field with mean rms ˜ 2.3 μJy/beam, cataloging 10,899 source components above 5× rms. By combining these radio data with UltraVISTA, optical, nearinfrared, and Spitzer/IRAC mid-infrared data, as well as X-ray data from the Chandra Legacy, Chandra COSMOS surveys, we gain insight into the emission mechanisms within our radio sources out to redshifts of z ˜ 5. From these emission characteristics we classify our sources as star forming galaxies or AGN. Using their multi-wavelength properties we further separate the AGN into sub-samples dominated by radiatively efficient and inefficient AGN, often referred to as high- and low-excitation emission line AGN.We compare our method with other results based on fitting of the sources' spectral energy distributions using both galaxy and AGN spectral models, and those based on the infrared-radio correlation. We study the fractional contributions of these sub-populations down to radio flux levels of ˜10 μJy. We find that at 3 GHz flux densities above ˜400 μJy quiescent, red galaxies, consistent with the low-excitation radio AGN class constitute the dominant fraction. Below densities of ˜200 μJy star-forming galaxies begin to constitute the largest fraction, followed by the low-excitation, and X-ray- and IR-identified high-excitation radio AGN.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. AGN contamination in total infrared determined star formation rates in dusty galaxies at z~2-3

    NASA Astrophysics Data System (ADS)

    Mazzei, Renato; Sharon, Chelsea E.; Riechers, Dominik

    2017-01-01

    Along with theoretical work that suggests feedback from active galactic nuclei (AGN) may quench star formation in massive galaxies, the temporal coincidence between the peak of cosmic star formation rates and black hole accretion rates suggests that AGN are common in star forming galaxies at z~2-3. Since star forming galaxies at these epochs are also very dusty, it is important that we correct galaxies’ long-wavelength properties for the presence of dust-obscured AGN in order to accurately capture their star formation rates and gas characteristics. We present a spectral energy distribution (SED) analysis of several un-lensed z~2-3 dusty star-forming galaxies from Pope et al. (2008) and Coppin et al. (2010), which we compare to several other high-z starbursts with well sampled SEDs. We constructed dust SEDs from existing Spitzer, Herschel, and SCUBA-2 photometry catalogues with data between 3.6 and 850 μm. For the SED fits, we used the Code Investigating GALaxy Emission (CIGALE), since it self-consistently determines the dust attenuation of stars and dust emission in the infrared in addition to determining the dust emission from obscured AGN (Noll et al. 2009; Serra et al. 2011). Our best-fit SEDs have typical reduced χ2 values between 0.2 and ~3. We use the output from CIGALE to determine the fraction of the total infrared luminosity (LTIR 8-1000 um) from star formation and from any potential obscured AGN. In order to examine the effects of buried AGN on the integrated Schmidt-Kennicutt relation (log(LTIR) vs. log(L'CO)), we compare our new LTIR to recently obtained CO(1-0) line luminosities from the Karl G. Jansky Very Large Array. Unaccounted for dust emission from AGN can artificially inflate the star formation rate inferred from LTIR, and may therefore offset starburst galaxies from the local Schmidt-Kennicutt relation and increase the slope of the relation, which can affect the inferred drivers of star formation.

  18. The XMM Cluster Survey: the interplay between the brightest cluster galaxy and the intracluster medium via AGN feedback

    NASA Astrophysics Data System (ADS)

    Stott, John P.; Hickox, Ryan C.; Edge, Alastair C.; Collins, Chris A.; Hilton, Matt; Harrison, Craig D.; Romer, A. Kathy; Rooney, Philip J.; Kay, Scott T.; Miller, Christopher J.; Sahlén, Martin; Lloyd-Davies, Ed J.; Mehrtens, Nicola; Hoyle, Ben; Liddle, Andrew R.; Viana, Pedro T. P.; McCarthy, Ian G.; Schaye, Joop; Booth, C. M.

    2012-05-01

    Using a sample of 123 X-ray clusters and groups drawn from the XMM Cluster Survey first data release, we investigate the interplay between the brightest cluster galaxy (BCG), its black hole and the intracluster/group medium (ICM). It appears that for groups and clusters with a BCG likely to host significant active galactic nuclei (AGN) feedback, gas cooling dominates in those with TX > 2 keV while AGN feedback dominates below. This may be understood through the subunity exponent found in the scaling relation we derive between the BCG mass and cluster mass over the halo mass range 1013 < M500 < 1015 M⊙ and the lack of correlation between radio luminosity and cluster mass, such that BCG AGN in groups can have relatively more energetic influence on the ICM. The LX-TX relation for systems with the most massive BCGs, or those with BCGs co-located with the peak of the ICM emission, is steeper than that for those with the least massive and most offset, which instead follows self-similarity. This is evidence that a combination of central gas cooling and powerful, well fuelled AGN causes the departure of the ICM from pure gravitational heating, with the steepened relation crossing self-similarity at TX= 2 keV. Importantly, regardless of their black hole mass, BCGs are more likely to host radio-loud AGN if they are in a massive cluster (TX≳ 2 keV) and again co-located with an effective fuel supply of dense, cooling gas. This demonstrates that the most massive black holes appear to know more about their host cluster than they do about their host galaxy. The results lead us to propose a physically motivated, empirical definition of 'cluster' and 'group', delineated at 2 keV.

  19. Accretion disk modeling of AGN continuum using non-LTE stellar atmospheres. [active galactic nuclei (AGN)

    NASA Technical Reports Server (NTRS)

    Sun, Wei-Hsin; Malkan, Matthew A.

    1988-01-01

    Active galactic nuclei (AGN) accretion disk spectra were calculated using non-LTE stellar atmosphere models for Kerr and Schwarzschild geometries. It is found that the Lyman limit absorption edge, probably the most conclusive observational evidence for the accretion disk, would be drastically distorted and displaced by the relativistic effects from the large gravitational field of the central black hole and strong Doppler motion of emitting material on the disk surface. These effects are especially pronounced in the Kerr geometry. The strength of the Lyman limit absorption is very sensitive to the surface gravity in the stellar atmosphere models used. For models at the same temperature but different surface gravities, the strength of the Lyman edge exhibits an almost exponential decrease as the surface gravity approach the Eddington limit, which should approximate the thin disk atmosphere. The relativistic effects as well as the vanishing of the Lyman edge at the Eddington gravity may be the reasons that not many Lyman edges in the rest frames of AGNs and quasars are found.

  20. 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.

  1. Average Heating Rate of Hot Atmospheres in Distant Galaxy Clusters by Radio AGN: Evidence for Continuous AGN Heating

    NASA Astrophysics Data System (ADS)

    Ma, Cheng-Jiun; McNamara, B.; Nulsen, P.; Schaffer, R.

    2011-09-01

    X-ray observations of nearby clusters and galaxies have shown that energetic feedback from AGN is heating hot atmospheres and is probably the principal agent that is offsetting cooling flows. Here we examine AGN heating in distant X-ray clusters by cross correlating clusters selected from the 400 Square Degree X-ray Cluster survey with radio sources in the NRAO VLA Sky Survey. The jet power for each radio source was determined using scaling relations between radio power and cavity power determined for nearby clusters, groups, and galaxies with atmospheres containing X-ray cavities. Roughly 30% of the clusters show radio emission above a flux threshold of 3 mJy within the central 250 kpc that is presumably associated with the brightest cluster galaxy. We find no significant correlation between radio power, hence jet power, and the X-ray luminosities of clusters in redshift range 0.1 -- 0.6. The detection frequency of radio AGN is inconsistent with the presence of strong cooling flows in 400SD, but cannot rule out the presence of weak cooling flows. The average jet power of central radio AGN is approximately 2 10^{44} erg/s. The jet power corresponds to an average heating of approximately 0.2 keV/particle for gas within R_500. Assuming the current AGN heating rate remained constant out to redshifts of about 2, these figures would rise by a factor of two. Our results show that the integrated energy injected from radio AGN outbursts in clusters is statistically significant compared to the excess entropy in hot atmospheres that is required for the breaking of self-similarity in cluster scaling relations. It is not clear that central AGN in 400SD clusters are maintained by a self-regulated feedback loop at the base of a cooling flow. However, they may play a significant role in preventing the development of strong cooling flows at early epochs.

  2. Interferometric IR observations: a diversity of dusty AGN tori

    NASA Astrophysics Data System (ADS)

    Burtscher, Leonard

    Interferometric observations in the infrared have resolved dusty structures on parsec and sub-parsec scales in more than two dozen AGNs by now -- a giant leap when considering that the first infrared interferometric observation of an extragalactic object is only about 10 years old. Since then, studies have confirmed the existence of dust in AGNs at its sublimation radius and have clearly dismissed models of very extended tori. Individual, well studied sources have been instrumental to reveal the complexity of these parsec-scale structures and statistical studies have shown a perplexing diversity in the population as a whole. Surprisingly, the diversity does not seem to follow the expected bimodality between optical type 1 and type 2 AGNs -- which are thought to be just face-on and edge-on tori. This central premise of viewing-angle dependent unified models is challenged if not dismissed by interferometric observations. The next step in understanding the AGN phenomenon -- beyond unification aspects -- is now to combine multi-scale observations with multi-scale simulations to constrain the physical processes driving the feeding and feedback of AGNs.

  3. 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.

  4. Mid-infrared Flux Variability in an Awakening AGN

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry

    We propose FORCAST spectroscopic observations between 8 um to 40 um near the nucleus of NGC 660. NGC 660 underwent an AGN outburst 6 years ago, which is an ideal case for studying AGN astrophysics in a rather quiecent system. However, this rare event has not yet been monitored. Our immidiate goal is to verify the MIR spectroscipic variabilitiy in NGC 660, and to study the AGN effects on dust destruction and ISM. We will compare the FORCAST spectra with the Spitzer IRS spectra (taken before the AGN outburst), including dust continuum, PAH emission, and high- and low-ionization emission lines. FORCAST's slit width is a close match to the IRS slit width, allowing a direct comparison of the spectra between FORCAST and IRS. Our single-slit Subaru COMICS spectrum taken after the outburst shows significantly weakened PAH emission and dust continuum, suggesting dust destruction. However, it is difficult to draw robust intepretations due to systematic uncertainties in the Subaru data. If dust destruction is confirmed in the post-outburst FORCAST observaitons, we will evaluate the energy budget using the MIR line ratio diagnostics, with archival X-ray and radio data. We will then propose cadence observations of MGC 660's nucleus to monitor the MIR flux variability, and employ the reverberation mapping technique to study NGC 660's AGN.

  5. VizieR Online Data Catalog: Type-2 AGN from XMM-COSMOS bolometric output (Lusso+, 2011)

    NASA Astrophysics Data System (ADS)

    Lusso, E.; Comastri, A.; Vignali, C.; Zamorani, G.; Treister, E.; Sanders, D.; Bolzonella, M.; Bongiorno, A.; Brusa, M.; Civano, F.; Gilli, R.; Mainieri, V.; Nair, P.; Aller, M.; Carollo, M.; Koekemoer, A. M.; Merloni, A.; Trump, J. R.

    2011-09-01

    Study of the multi-wavelength properties of a sample of 255 spectroscopically identified X-ray selected Type-2 AGN from the XMM-COSMOS survey. For each source, X-ray ID, spectroscopic redshift, logarithm of the 2-10keV luminosity, logarithm of the bolometric luminosity, bolometric correction, logarithm of the stellar mass, star formation rate, absolute magnitude MU, absolute magnitude MV, absolute magnitude MJ (Johnson-Kron-Cousin system), morphological class. (1 data file).

  6. 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.

  7. VizieR Online Data Catalog: A 3.5mm polarimetric survey of radio-loud AGNs (Agudo+, 2010)

    NASA Astrophysics Data System (ADS)

    Agudo, I.; Thum, C.; Wiesemeyer, H.; Krichbaum, T. P.

    2010-09-01

    In Table 1, we present our sample of 145 observed sources (see also Fig. 1) which has been built essentially from the 138 radio-loud AGNs in the IRAM pointing sources that were contained in the 1Jy catalog (Kuhr et al. 1981, Cat. VIII/5) and/or in the catalog of 404 compact radio sources by Perley (1982, Cat. J/AJ/87/859). (2 data files).

  8. VizieR Online Data Catalog: Suzaku view of highly ionized outflows in AGN (Gofford+, 2013)

    NASA Astrophysics Data System (ADS)

    Gofford, J.; Reeves, J. N.; Tombesi, F.; Braito, V.; Turner, T. J.; Miller, L.; Cappi, M.

    2014-03-01

    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 FeXXV Heα and/or FeXXVI Lyα 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>~6.7keV in 20/51 sources at the PMC>=95% level, which corresponds to ~40% 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 FeXXV Heα and FeXXVI Lyα at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the FeK absorption components are log(NH/cm2)~23 and log({xi}/erg/cm/s)~4.5, respectively. Measured outflow velocities span a continuous range from <1500km/s up to ~100000km/s, with mean and median values of ~0.1c and ~0.056c, 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. (2 data files).

  9. 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.

  10. Circular Polarization in AGNs: Polarity and Spectra

    NASA Astrophysics Data System (ADS)

    Aller, M. F.; Aller, H. D.; Plotkin, R. M.

    2005-12-01

    Circular polarization (Stokes V) observations potentially provide information on the nature and origin of the underlying magnetic fields in AGNs. We have been systematically monitoring a group of sources with detectable circular polarization (V>0.1 percent, a level set by the instrumental polarization of our system) in all 4 Stokes parameters at 8.0 and 4.8 GHz since 2000, and also at 14.5 GHz since November 2003, with the University of Michigan prime focus paraboloid antenna. These data are compared with historical observations obtained with the same instrument at 8.0 and 4.8 GHz extending back to 1978. Specific goals are to study the temporal spectral behavior of Stokes V and its relation to variability in total flux and linear polarization, and to investigate the question of polarity stability on decade-long time scales using data obtained with the same instrumentation and at the same frequencies. The data are consistent with linear-to-circular mode conversion in partially opaque regions of the source. We find examples of polarity changes with time at one or more frequencies associated with outbursts in total flux and linear polarization, and polarity differences within the 3 frequencies at a single epoch in one case, 3C 279. Such behavior argues against the notion that the sign of Stokes V is a simple tracer of the net flow of magnetic energy from the central engine to the jet or an indicator of the direction of rotation of the spinning central black hole/accretion disk via the winding up of the initial seed magnetic field. This work was supported in part by NSF grant AST-0307629 and by funds from the University of Michigan.

  11. 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).

  12. 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.

  13. BAT AGN Spectroscopic Survey - III. An observed link between AGN Eddington ratio and narrow-emission-line ratios

    NASA Astrophysics Data System (ADS)

    Oh, Kyuseok; Schawinski, Kevin; Koss, Michael; Trakhtenbrot, Benny; Lamperti, Isabella; Ricci, Claudio; Mushotzky, Richard; Veilleux, Sylvain; Berney, Simon; Crenshaw, D. Michael; Gehrels, Neil; Harrison, Fiona; Masetti, Nicola; Soto, Kurt T.; Stern, Daniel; Treister, Ezequiel; Ueda, Yoshihiro

    2017-01-01

    We investigate the observed relationship between black hole mass (MBH), bolometric luminosity (Lbol) and Eddington ratio (λEdd) with optical emission-line ratios ([N II] λ6583/Hα, [S II] λλ6716, 6731/Hα, [O I] λ6300/Hα, [O III] λ5007/Hβ, [Ne III] λ3869/Hβ and He II λ4686/Hβ) of hard X-ray-selected active galactic nuclei (AGN) from the BAT AGN Spectroscopic Survey. We show that the [N II] λ6583/Hα ratio exhibits a significant correlation with λEdd (RPear = -0.44, p-value = 3 × 10-13, σ = 0.28 dex), and the correlation is not solely driven by MBH or Lbol. The observed correlation between [N II] λ6583/Hα ratio and MBH is stronger than the correlation with Lbol, but both are weaker than the λEdd correlation. This implies that the large-scale narrow lines of AGN host galaxies carry information about the accretion state of the AGN central engine. We propose that [N II] λ6583/Hα is a useful indicator of Eddington ratio with 0.6 dex of rms scatter, and that it can be used to measure λEdd and thus MBH from the measured Lbol, even for high-redshift obscured AGN. We briefly discuss possible physical mechanisms behind this correlation, such as the mass-metallicity relation, X-ray heating, and radiatively driven outflows.

  14. THE SPATIAL CLUSTERING OF ROSAT ALL-SKY SURVEY AGNs. II. HALO OCCUPATION DISTRIBUTION MODELING OF THE CROSS-CORRELATION FUNCTION

    SciTech Connect

    Miyaji, Takamitsu; Aceves, Hector; Krumpe, Mirko; Coil, Alison L.

    2011-01-10

    This is the second paper of a series that reports on our investigation of the clustering properties of active galactic nuclei (AGNs) in the ROSAT All-Sky Survey (RASS) through cross-correlation functions (CCFs) with Sloan Digital Sky Survey (SDSS) galaxies. In this paper, we apply the Halo Occupation Distribution (HOD) model to the CCFs between the RASS broad-line AGNs with SDSS luminous red galaxies (LRGs) in the redshift range 0.16 < z < 0.36 that was calculated in Paper I. In our HOD modeling approach, we use the known HOD of LRGs and constrain the HOD of the AGNs by a model fit to the CCF. For the first time, we are able to go beyond quoting merely a 'typical' AGN host halo mass, M{sub h}, and model the full distribution function of AGN host dark matter halos. In addition, we are able to determine the large-scale bias and the mean M{sub h} more accurately. We explore the behavior of three simple HOD models. Our first model (Model A) is a truncated power-law HOD model in which all AGNs are satellites. With this model, we find an upper limit to the slope ({alpha}) of the AGN HOD that is far below unity. The other two models have a central component, which has a step function form, where the HOD is constant above a minimum mass, without (Model B) or with (Model C) an upper mass cutoff, in addition to the truncated power-law satellite component, similar to the HOD that is found for galaxies. In these two models we find that the upper limits on {alpha} are still below unity, with {alpha} {approx}< 0.95 and {alpha} {approx}< 0.84 for Models B and C, respectively. Our analysis suggests that the satellite AGN occupation increases slower than, or may even decrease with, M{sub h}, in contrast to the satellite HODs of luminosity-threshold samples of galaxies, which, in contrast, grow approximately as (N{sub s}) {proportional_to} M{sup {alpha}}{sub h} with {alpha} {approx} 1. These results are consistent with observations that the AGN fraction in groups and clusters

  15. Time-Dependent Photoionization of Gas Outflows in AGN

    NASA Astrophysics Data System (ADS)

    Elhoussieny, Ehab E.; Bautista, M.; Garcia, J.; Kallman, T. R.

    2013-01-01

    Gas outflows are fundamental components of Active Galactic Nuclei (AGN) activity. Time-variability of ionizing radiation, which is characteristic of AGN in various different time scales, may produce non-equilibrium photoionization conditions over a significant fraction of the flow and yields supersonically moving cooling/heating fronts. These fast fronts create pressure imbalances that can only be resolved by fragmentation of the flow and acceleration of such fragments. This mechanism can explain the kinematic structure of low ionization BAL systems (FeLoBAL). This mechanism may also have significant effects on other types of outflows given the wide range of variability time scales in AGN. We will study these effects in detail by constructing time-dependent photoionization models of the outflows and incorporating these models into radiative-hydrodynamic simulations.

  16. Disentangling AGN-Host Galaxy Interactions with Chandra

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng

    2014-11-01

    The circum-nuclear region in active galaxies is often complex with presence of high excitation gas, collimated radio outflow, and star forming regions, besides the active central supermassive black hole. In Chandra studies of a number of archetypal Seyfert galaxies to investigate AGN-host galaxy interaction, we were able to evaluate the mass outflow rate and shock heating by radio jet. For galaxies in the throes of a violent merging event such as NGC6240, we were able to resolve 70MK hot gas surrounding the double nuclei and discovered a large scale soft X-ray halo. The unique resolving power of Chandra also enables more discovery of such dual AGN systems and signs of past AGN outburst activities.

  17. 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.

  18. Multiwavelength studies of X-ray selected extragalactic sample

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    The joint catalogue of Active Galactic Nuclei selected from optical identications of X-ray sources was created as a combination of two samples: Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both are based on optical identications of X-ray sources from ROSAT catalogues using low-dispersion spectra of Hamburg Quasar Survey (HQS). However, HRC and BHRC contain a number of misidentications and using the recent optical and multiwavelength (MW) catalogues we have revised both samples excluding false AGN and adding new genuine ones. Thus a new large homogeneous complete sample of 4253 X-ray selected AGN was created. 3352 of them are listed in the Catalogue of QSOs and Active Galaxies and 387 also are in Roma Multifrequency Catalogue of Blazars. 901 candidate AGN are subjects for further study. We classified 173 of these objects using their SDSS DR12 spectra. Following activity types were revealed: 61 AGN, 21 HII galaxies, 12 emission-line galaxies without definite type, 71 absorption-line galaxies, 2 stars, and 6 were classified as "Unknown". 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"). As a result, the sample of genuine AGN was enlarged to 3413 objects. We have retrieved MW data from recent catalogues and carried out statistical investigations for the whole AGN sample. An attempt to find connections between fluxes in different bands for different types of sources, and to identify their characteristics thus confirming candidate AGNs has been carried out. We have analyzed X-ray properties of these sources to nd a limit between normal galaxies and X-ray AGN.

  19. 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

  20. THE SPATIAL CLUSTERING OF ROSAT ALL-SKY SURVEY ACTIVE GALACTIC NUCLEI. III. EXPANDED SAMPLE AND COMPARISON WITH OPTICAL ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Krumpe, Mirko; Coil, Alison L.; Miyaji, Takamitsu; Aceves, Hector

    2012-02-10

    This is the third paper in a series that reports on our investigation of the clustering properties of active galactic nuclei (AGNs) identified in the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS). In this paper, we extend the redshift range to 0.07 < z < 0.50 and measure the clustering amplitudes of both X-ray-selected and optically selected SDSS broad-line AGNs with and without radio detections as well as for X-ray-selected narrow-line RASS/SDSS AGNs. We measure the clustering amplitude through cross-correlation functions (CCFs) with SDSS galaxies and derive the bias by applying a halo occupation distribution model directly to the CCFs. We find no statistically convincing difference in the clustering of X-ray-selected and optically selected broad-line AGNs, as well as with samples in which radio-detected AGNs are excluded. This is in contrast to low-redshift optically selected narrow-line AGNs, where radio-loud AGNs are found in more massive halos than optical AGNs without a radio detection. The typical dark matter halo masses of our broad-line AGNs are log (M{sub DMH}/[h{sup -1} M{sub Sun }]) {approx} 12.4-13.4, consistent with the halo mass range of typical non-AGN galaxies at low redshifts. We find no significant difference between the clustering of X-ray-selected narrow-line AGNs and broad-line AGNs. We confirm the weak dependence of the clustering strength on AGN X-ray luminosity at a {approx}2{sigma} level. Finally, we summarize the current picture of AGN clustering to z {approx} 1.5 based on three-dimensional clustering measurements.

  1. The NuSTAR view of radio-quiet AGN

    NASA Astrophysics Data System (ADS)

    Marinucci, Andrea

    AUTHORS: A. Marinucci and the NuSTAR Team ABSTRACT: The Nuclear Spectroscopic Telescope Array (NuSTAR), thanks to its improved sensitivity in hard X-rays with respect to coded aperture observatories, is providing new and exciting results on radio-quiet AGN. In this talk I will present results from the NuSTAR AGN Physics program after the first two years of science operations. In particular, measurements of the black hole spin and coronal temperature in nearby sources will be discussed.

  2. 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

  3. The clustering properties of radio-selected AGN and star-forming galaxies up to redshifts z ˜ 3

    NASA Astrophysics Data System (ADS)

    Magliocchetti, M.; Popesso, P.; Brusa, M.; Salvato, M.; Laigle, C.; McCracken, H. J.; Ilbert, O.

    2017-01-01

    We present the clustering properties of a complete sample of 968 radio sources detected at 1.4 GHz by the Very Large Array (VLA)-COSMOS survey with radio fluxes brighter than 0.15 mJy. 92 per cent have redshift determinations from the Laigle et al. catalogue. Based on their radio luminosity, these objects have been divided into 644 AGN and 247 star-forming galaxies. By fixing the slope of the autocorrelation function to γ = 2, we find r_0=11.7^{+1.0}_{-1.1} Mpc for the clustering length of the whole sample, while r_0=11.2^{+2.5}_{-3.3} Mpc and r_0=7.8^{+1.6}_{-2.1} Mpc (r_0=6.8^{+1.4}_{-1.8} Mpc for z ≤ 0.9) are, respectively, obtained for AGN and star-forming galaxies. These values correspond to minimum masses for dark matter haloes of M_min=10^{13.6^{+0.3}_{-0.6}} M⊙ for radio-selected AGN and M_min=10^{13.1^{+0.4}_{-1.6}} M⊙ for radio-emitting star-forming galaxies (M_min=10^{12.7^{+0.7}_{-2.2}} M⊙ for z ≤ 0.9). Comparisons with previous works imply an independence of the clustering properties of the AGN population with respect to both radio luminosity and redshift. We also investigate the relationship between dark and luminous matter in both populations. We obtain /Mhalo ≲ 10- 2.7 for AGN, and /Mhalo ≲ 10- 2.4 in the case of star-forming galaxies. Furthermore, if we restrict to z ≲ 0.9 star-forming galaxies, we derive /Mhalo ≲ 10- 2.1, result that clearly shows the cosmic process of stellar build-up as one moves towards the more local universe. Comparisons between the observed space density of radio-selected AGN and that of dark matter haloes show that about one in two haloes is associated with a black hole in its radio-active phase. This suggests that the radio-active phase is a recurrent phenomenon.

  4. 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

  5. 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.

  6. 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

  7. Kinematic signatures of AGN feedback in moderately powerful radio galaxies at z ~ 2 observed with SINFONI

    NASA Astrophysics Data System (ADS)

    Collet, C.; Nesvadba, N. P. H.; De Breuck, C.; Lehnert, M. D.; Best, P.; Bryant, J. J.; Hunstead, R.; Dicken, D.; Johnston, H.

    2016-02-01

    Most successful galaxy formation scenarios now postulate that the intense star formation in massive, high-redshift galaxies during their major growth period was truncated when powerful AGNs launched galaxy-wide outflows of gas that removed large parts of the interstellar medium. SINFONI imaging spectroscopy of the most powerful radio galaxies at z ~ 2 show clear signatures of such winds, but are too rare to be good representatives of a generic phase in the evolution of all massive galaxies at high redshift. Here we present SINFONI imaging spectroscopy of the rest-frame optical emission-line gas in 12 radio galaxies at redshifts ~2. Our sample spans a range in radio power that is intermediate between the most powerful radio galaxies with known wind signatures at these redshifts and vigorous starburst galaxies, and are about two orders of magnitude more common than the most powerful radio galaxies. Thus, if AGN feedback is a generic phase of massive galaxy evolution for reasonable values of the AGN duty cycle, these are just the sources where AGN feedback should be most important. Our sources show a diverse set of gas kinematics ranging from regular velocity gradients with amplitudes of Δv = 200-400 km s-1 consistent with rotating disks to very irregular kinematics with multiple velocity jumps of a few 100 km s-1. Line widths are generally high, typically around FWHM = 800 km s-1, more similar to the more powerful high-z radio galaxies than mass-selected samples of massive high-z galaxies without bright AGNs, and consistent with the velocity range expected from recent hydrodynamic models. A broad Hα line in one target implies a black hole mass of a few 109 M⊙. Velocity offsets of putative satellite galaxies near a few targets suggest dynamical masses of a few 1011 M⊙ for our sources, akin to the most powerful high-z radio galaxies. Ionized gas masses are 1-2 orders of magnitude lower than in the most powerful radio galaxies, and the extinction in the gas is

  8. INTEGRAL observations of six AGN in the Galactic Plane

    NASA Astrophysics Data System (ADS)

    Soldi, S.; Beckmann, V.; Bassani, L.; Courvoisier, T. J.-L.; Landi, R.; Malizia, A.; Dean, A. J.; de Rosa, A.; Fabian, A. C.; Walter, R.

    2005-12-01

    We present results on approximately one year of INTEGRAL observations of six AGN detected during the regular scans of the Galactic Plane. The sample is composed by five Seyfert 2 objects (MCG 05 23 16, NGC 4945, the Circinus galaxy, NGC 6300, ESO 103 G35) and the radio galaxy Centaurus A. The continuum emission of each of these sources is well represented by a highly absorbed (N_H>1022 cm-2) power law, with average spectral index Γ = 1.9 ± 0.3. A high energy exponential cut-off at Ec ˜ 50 ~keV is required to fit the spectrum of the Circinus galaxy, whereas a lower limit of 130 keV has been found for NGC 4945 and no cut-off has been detected for NGC 6300 in the energy range covered by these INTEGRAL data. The flux of Centaurus A was found to vary by a factor of ~2 in 10 months, showing a spectral change between the high and low state, which can be modelled equally well by a change in the absorption (NH from 17 to 33 × 1022 cm-2) or by the presence of a cut-off at ⪆120 keV in the low state spectrum. A comparison with recently reprocessed BeppoSAX/PDS data shows a general agreement with INTEGRAL results. The high energy cut-off in the hard X-ray spectra appears to be a common but not universal characteristic of Seyfert 2 and to span a wide range of energies.

  9. The MOSDEF Survey: AGN Multi-wavelength Identification, Selection Biases, and Host Galaxy Properties

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Coil, Alison L.; Aird, James; Reddy, Naveen; Shapley, Alice; Freeman, William R.; Kriek, Mariska; Leung, Gene C. K.; Mobasher, Bahram; Price, Sedona H.; Sanders, Ryan L.; Shivaei, Irene; Siana, Brian

    2017-01-01

    We present results from the MOSFIRE Deep Evolution Field (MOSDEF) survey on the identification, selection biases, and host galaxy properties of 55 X-ray, IR, and optically selected active galactic nuclei (AGNs) at 1.4< z< 3.8. We obtain rest-frame optical spectra of galaxies and AGNs and use the BPT diagram to identify optical AGNs. We examine the uniqueness and overlap of the AGNs identified at different wavelengths. There is a strong bias against identifying AGNs at any wavelength in low-mass galaxies, and an additional bias against identifying IR AGNs in the most massive galaxies. AGN hosts span a wide range of star formation rates (SFRs), similar to inactive galaxies once stellar mass selection effects are accounted for. However, we find (at ∼2–3σ significance) that IR AGNs are in less dusty galaxies with relatively higher SFR and optical AGNs in dusty galaxies with relatively lower SFR. X-ray AGN selection does not display a bias with host galaxy SFR. These results are consistent with those from larger studies at lower redshifts. Within star-forming galaxies, once selection biases are accounted for, we find AGNs in galaxies with similar physical properties as inactive galaxies, with no evidence for AGN activity in particular types of galaxies. This is consistent with AGNs being fueled stochastically in any star-forming host galaxy. We do not detect a significant correlation between SFR and AGN luminosity for individual AGN hosts, which may indicate the timescale difference between the growth of galaxies and their supermassive black holes.

  10. SPITZER MID-IR SPECTROSCOPY OF POWERFUL 2 JY AND 3CRR RADIO GALAXIES. I. EVIDENCE AGAINST A STRONG STARBURST-AGN CONNECTION IN RADIO-LOUD AGN

    SciTech Connect

    Dicken, D.; Axon, D.; Robinson, A.; Kharb, P.; Tadhunter, C.; Ramos Almeida, C.; Morganti, R.; Kouwenhoven, M. B. N.; Spoon, H.; Inskip, K. J.; Holt, J.; Nesvadba, N. P. H.

    2012-02-01

    We present deep Spitzer/Infrared Spectrograph (IRS) spectra for complete samples of 46 2 Jy radio galaxies (0.05 < z < 0.7) and 19 3CRR FRII radio galaxies (z < 0.1), and use the detection of polycyclic aromatic hydrocarbon (PAH) features to examine the incidence of contemporaneous star formation and radio-loud active galactic nucleus (AGN) activity. Our analysis reveals PAH features in only a minority (30%) of the objects with good IRS spectra. Using the wealth of complementary data available for the 2 Jy and 3CRR samples we make detailed comparisons between a range of star formation diagnostics: optical continuum spectroscopy, mid- to far-IR (MFIR) color, far-IR excess and PAH detection. There is good agreement between the various diagnostic techniques: most candidates identified to have star formation activity on the basis of PAH detection are also identified using at least two of the other techniques. We find that only 35% of the combined 2 Jy and 3CRR sample show evidence for recent star formation activity (RSFA) at optical and/or MFIR wavelengths. This result argues strongly against the idea of a close link between starburst and powerful radio-loud AGN activity, reinforcing the view that, although a large fraction of powerful radio galaxies may be triggered in galaxy interactions, only a minority are triggered at the peaks of star formation activity in major, gas-rich mergers. However, we find that compact radio sources (D < 15 kpc) show a significantly higher incidence of RSFA (>75%) than their more extended counterparts ( Almost-Equal-To 15%-25%). We discuss this result in the context of a possible bias toward the selection of compact radio sources triggered in gas-rich environments.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. Gamma-ray monitoring of AGN and galactic black hole candidates by the Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Wheaton, Wm. A.; Ling, James C.; Skelton, R. T.; Harmon, Alan; Fishman, Gerald J.; Meegan, Charles A.; Paciesas, William S.; Rubin, Brad; Wilson, Robert B.; Gruber, Duane E.

    1992-01-01

    The Burst and Transient Spectroscopy Experiment (BATSE) on the Compton Gamma-Ray Observatory has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV-10 MeV range of both AGN and Galactic black hole candidates such as Cygnus X-1, using the occultation of cosmic sources by the Earth. Progress in background modeling indicates that the data accept region, or fit window tau, around the occultation step can be substantially increased over that conservatively assumed in earlier estimates of BATSE's Earth occultation sensitivity. We show samples of large-tau fits to background and source edges. As a result we expect to be able to perform long-term monitoring of Cygnus X-1 and many of the brighter AGN for the duration of the CGRO mission.

  16. 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.

  17. 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.

  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. Towards A Complete Census of Compton-thick AGN and N_H Distribution in the Local Universe

    NASA Astrophysics Data System (ADS)

    Annuar, A.; Gandhi, P.; Alexander, D.; Asmus, D.; Goulding, A.; Harrison, C.; Lansbury, G.

    2014-07-01

    Many studies have shown that Compton-thick AGNs (CTAGNs) provide important contribution to the cosmic X-ray background spectrum (˜25% at 20keV). They are expected to dominate the Seyfert 2 population in the local universe, yet only ˜20 bona fide CTAGNs are known. We present an updated census of CTAGN population in the local universe using a volume-limited AGN sample complete to D=15Mpc. Intrinsic relations between 2-10keV X-ray luminosity and mid-IR emission at 12μm, [OIV]λ25.68μm and [NeV]λ14.32μm are investigated, and it is found that the emission at 12μm has the tightest correlation with the X-ray luminosity.Candidates for CTAGN are then selected using this relation and by comparing their 12μm luminosity with the observed X-ray luminosity.We also investigate the Compton-thick nature of these sources using the optical [OIII]λ5007{A}:X-ray diagnostic for comparison, and find that 35-50% of the sample are Compton-thick,of which 10-20% would be missed with the optical approach.Finally, we estimate the intrinsic N_{H} distribution of AGN population in the local universe from this analysis, and show that up to 70% of the sources are heavily obscured (N_{H}>10^{23} cm^{-2}), with ≥50% lying in the Compton-thick regime (N_{H}>10^{24} cm^{-2}).This work provides a well-defined local benchmark for AGN obscuration studies.

  20. 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.

  1. 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.

  2. The Evolution of the AGN population in the MORGANA model

    NASA Astrophysics Data System (ADS)

    Fontanot, F.; Monaco, P.; Cristiani, S.; Tozzi, P.

    2008-10-01

    We present the results of the MOdel for the Rise of Galaxies aNd Agns (MORGANA), that includes in a self-consistent way the accretion of matter onto Super-Massive Black Holes. We compare MORGANA predictions to the observed evolution of the AGN space density (inferred from optical and X-ray surveys) and we find that that it is possible to reproduce the apparent downsizing of the AGN population in the framework of concordance cosmology. We will show that this result is likely due to the improved treatment of gas cooling and feedback in MORGANA, and in particular to the modeling of the stellar kinetic feedback, arising in star-forming bulges as a consequence of the level of turbolence. On the other hand, the predicted low-mass end of BH-bulge relation is steeper than observed: we discuss this disagreement on the light of the predicted excess of small bulges, which is common to several models of galaxy formation and evolution. Finally we will show that a stronger constrain on the relative importance of the physical processes involved in the build up of the AGN population move from the observed redshift evolution of the BH-Bulge relation.

  3. 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.

  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. First Results from the NuSTAR AGN Physics Program

    NASA Astrophysics Data System (ADS)

    Brenneman, Laura; Fuerst, F.; Matt, G.; Walton, D.; Madejski, G. M.; Marinucci, A.; Elvis, M.; Risaliti, G.; Harrison, F.; Stern, D.; Boggs, S.; Christensen, F.; Craig, W. W.; Zhang, W.; NuSTAR Team

    2013-04-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR, launched June 2012) is revolutionizing our knowledge of the physics at work in active galactic nuclei (AGN). With its high collecting area, focusing optics and low background from 3-79 keV, NASA's newest X-ray observatory is providing an unprecedented look at the spectral and timing properties of AGN in this energy range, which have been notoriously difficult to access. NuSTAR has observed several AGN to date simultaneously with XMM-Newton, Suzaku and/or Swift for the purposes of understanding their coronal properties (e.g., plasma temperature, optical depth) and measuring the spins of their supermassive black holes. We present the first results from these observing campaigns, highlighting the spectral and timing analysis of the bright, nearby AGN IC 4329A, NGC 4151, NGC 1365 and MCG--6-30-15. These are the highest signal-to-noise datasets ever obtained across the 0.2-79 keV energy band for these three sources, allowing us to cleanly deconvolve the X-ray continuum, absorption and reflection components in each galaxy for the first time via time-averaged and time-resolved spectroscopy.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. Incidence of WISE-Selected Obscured AGNs in Major Mergers and Interactions from the SDSS

    NASA Astrophysics Data System (ADS)

    Weston, Madalyn; McIntosh, Daniel H.; Brodwin, Mark; Mann, Justin; Cooper, Andrew; McConnell, Adam; Nielson, Jennifer L.

    2017-01-01

    We use the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS) to confirm a connection between dust-obscured active galactic nuclei (AGNs) and galaxy merging. Using a new, volume-limited (z≤0.08) catalog of visually-selected major mergers and galaxy-galaxy interactions from the SDSS, with stellar masses above 2×10^10 M⊙, we find that major mergers (interactions) are 5--17 (3--5) times more likely to have red [3.4]-[4.6] colors associated with dust-obscured or `dusty' AGNs, compared to non-merging galaxies with similar masses. Using published fiber spectral diagnostics, we map the [3.4]-[4.6] versus [4.6]-[12] colors of different emission-line galaxies and find one-quarter of Seyferts have colors indicative of a dusty AGN. We find that AGNs are five times more likely to be obscured when hosted by a merging galaxy, half of AGNs hosted by a merger are dusty, and we find no enhanced frequency of optical AGNs in merging over non-merging galaxies. We conclude that undetected AGNs missed at shorter wavelengths are at the heart of the ongoing AGN-merger connection debate. The vast majority of mergers hosting dusty AGNs are star-forming and located at the centers of Mhalo<10^13 M⊙ groups. Assuming plausibly short duration dusty-AGN phases, we speculate that a large fraction of gas-rich mergers experience a brief obscured AGN phase, in agreement with the strong connection between central star formation and black hole growth seen in merger simulations. We will use the WISE-selected AGNs (and AGNs selected by other methods) to perform SED analysis of mergers and interactions and dissect the SEDs to disentangle AGN and SF activity.

  12. 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

  13. Modeling the reverberation of optical polarization in AGN

    NASA Astrophysics Data System (ADS)

    Rojas Lobos, P. A.; Goosmann, R.; Marin, F.

    2016-12-01

    According to the standard paradigm, the strong and compact luminosity of active galactic nuclei (AGN) is due to multi-temperature black body emission originating from an accretion disk formed around a supermassive black hole. This central engine is thought to be surrounded by a dusty region along the equatorial plane and by ionized winds along the poles. The innermost regions cannot yet be resolved neither in the optical nor in the infrared and it is fair to say that we still lack a satisfactory understanding of the physical processes, geometry and composition of the central (sub-parsec) components of AGN. Like spectral or polarimetric observations, the reverberation data needs to be modeled in order to infer constraints on the AGN geometry (such as the inner radius or the half-opening angle of the dusty torus). In this research note, we present preliminary modeling results using a time-dependent Monte Carlo method to solve the radiative transfer in a simplified AGN set up. We investigate different model configurations using both polarization and time lags and find a high dependency on the geometry to the time-lag response. For all models there is a clear distinction between edge-on or face-on viewing angles for fluxes and time lags, the later showing a higher wavelength-dependence than the former. Time lags, polarization and fluxes point toward a clear dichotomy between the different inclinations of AGN, a method that could help us to determine the true orientation of the nucleus in Seyfert galaxies.

  14. PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Young; Trippe, Sascha; Sohn, Bong Won; Oh, Junghwan; Park, Jong-Ho; Lee, Sang-Sung; Lee, Taeseok; Kim, Daewon

    2015-10-01

    Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to >10^{8.01} K and >10^{9.86} K, respectively. Degrees of linear polarization m_{L} are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with m_{L} ˜ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.

  15. 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.

  16. Probing the Physical Properties and Origins of Ultra-fast Outflows in AGN

    NASA Astrophysics Data System (ADS)

    Kraemer, Steven B.; Tombesi, Francesco; Bottorff, Mark

    2017-01-01

    Approximately half of Type 1 AGN possess intrinsic absorption and high resolution UV and X-ray spectroscopy have revealed that the absorbing gas is radially outflowing, with velocities of 100s to 1000s km/sec. X-ray ("warm") absorbers, originally revealed by the presence of bound-free edges of O~VII and O~VIII, are more highly ionized than their UV counterparts, and photo-ionization modeling studies have determined that they have ionization parameters of logU ~ -1 to 1. Recently, muchmore highly ionized gas, with logU > 2, has been detected in XMM-Newton spectra, as evidenced by absorption lines from H- and He-like Fe. Some of these absorbers, ``Ultra Fast Outlows (UFOs)'', have radial velocities up to 0.2c. We have undertaken a detailed photo-ionization study of high-ionization Fe absorbers, both UFOs and non-UFOs, in a sample of AGN observed by XMM-Newton. We find that the UFOs are completely Compton-cooled, unlike the non-UFOS. Both types are too highly ionized to be radiatively accelerated, hence they are more likely driven via Magneto-Hydrodynamic processes. Their large column densities and velocity gradients are consistent with flows along magnetic streamlines emanating from accretion disks. Open questions include: the temporal stability of the UFOs, the apparent lack of non-UFOs in UFO sources, and their relationship to warm absorbers.

  17. CHANG-ES - VIII. Uncovering hidden AGN activity in radio polarization

    NASA Astrophysics Data System (ADS)

    Irwin, Judith A.; Schmidt, Philip; Damas-Segovia, A.; Beck, Rainer; English, Jayanne; Heald, George; Henriksen, Richard N.; Krause, Marita; Li, Jiang-Tao; Rand, Richard J.; Wang, Q. Daniel; Wiegert, Theresa; Kamieneski, Patrick; Paré, Dylan; Sullivan, Kendall

    2017-01-01

    We report on C-band (5-7 GHz) observations of the galaxy, NGC 2992, from the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES) sample. This galaxy displays an embedded nuclear double-lobed radio morphology within its spiral disc, as revealed in linearly polarized emission but not in total intensity emission. The radio lobes are kpc-sized, similar to what has been observed in the past for other Seyfert galaxies, and show ordered magnetic fields. NGC 2992 has shown previous evidence for AGN-related activity, but not the linearly polarized radio features that we present here. We draw attention to this galaxy as the first clear example (and prototype) of bipolar radio outflow that is revealed in linearly polarized emission only. Such polarization observations, which are unobscured by dust, provide a new tool for uncovering hidden weak active galactic nucleus (AGN) activity which may otherwise be masked by brighter unpolarized emission within which it is embedded. The radio lobes observed in NGC 2992 are interacting with the surrounding interstellar medium (ISM) and offer new opportunities to investigate the interactions between nuclear outflows and the ISM in nearby galaxies. We also compare the radio emission with a new CHANDRA X-ray image of this galaxy. A new CHANG-ES image of NGC 3079 is also briefly shown as another example as to how much more obvious radio lobes appear in linear polarization as opposed to total intensity.

  18. Galaxy Interactions and AGN-triggering to z~1: an unprecedented new view from the Hyper Suprime-Cam Survey

    NASA Astrophysics Data System (ADS)

    Goulding, Andy D.; Greene, Jenny E.; Bezanson, Rachel; Greco, Johnny; Johnson, Sean; Medezinski, Elinor; Strauss, Michael A.; HSC Collaboration

    2017-01-01

    Collisions and interactions between galaxies are thought to be pivotal stages in their formation and evolution, causing the rapid production of new stars, and may also serve as a mechanism for fueling supermassive black holes (BH). Harnessing the exquisite spatial resolution (0.3—0.7 arcsec) afforded by the new 1400 deg2 Hyper Suprime-Cam (HSC) Survey, we present our new constraints on the importance of major and minor mergers in growing BHs throughout the last ~7 Gyrs. Utilizing the first ~170 deg2 of the HSC Survey, and mid-infrared observations in the WISE All-Sky survey, we have robustly selected active galactic nuclei (AGN), starburst, and mass-matched control galaxy samples, totaling ~120,000 spectroscopically confirmed systems at i<22 mag. We identify galaxy interactions using a novel machine-learning technique, and use these data to map the growth of BHs as a function of interaction-stage, redshift and AGN luminosity, ultimately providing the necessary large-number statistics required to investigate merger—AGN triggering in the context of galaxy evolution out to z~1.

  19. The complexity of the coronal line region in AGNs: Gas-jet interactions and outflows revealed by NIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ardila, Alberto; Prieto, Almudena; Mazzalay, Ximena

    2016-08-01

    Apart from the classical broad line region (BLR) at small core distances, and the extended classical narrow-line region (NLR), a subset of active galactic nuclei (AGN) show, in their spectra, lines from very highly ionised atoms, known as Coronal lines (CLs). The precise nature and origin of these CLs remain uncertain. Advances on this matter include the determination of the size and morphology of the CLR by means of optical HST and ground-based AO imaging/spectroscopy in a few AGNs. The results indicate CLRs with sizes varying from compact (~30 pc) to extended (~200 pc) emission and aligned preferentially with the direction of the lower ionisation cones seen in these sources. In this talk, we present results of a pioneering work aimed at studying the CLR in the near-infrared region on a selected sample of nearby AGNs. The excellent angular resolution of the data allowed us to resolve and map the extension of the coronal line gas and compare it to that emitting low- and mid-ionization lines. In most cases, the very good match between the radio emission and the CLR suggest that at least part of the high-ionization gas is jet-driven. Results from photoionization models where the central engine is the only source of energy input strongly fail at reproducing the observed line ratios, mainly at distances larger than 60 pc from the centre. We discuss here other processes that should be at work to enhance this energetic emission and suggest that the presence of coronal lines in AGNs is an unambiguous signature of feedback processes in these sources.

  20. OT1_dweedman_1: Comparing [CII] 158 micron Luminosities to Spectral Properties of Luminous Starburst Galaxies and AGN

    NASA Astrophysics Data System (ADS)

    Weedman, D.

    2010-07-01

    Herschel PACS spectroscopy of the [CII] emission line at 158 microns is proposed for a carefully selected sample of 123 sources that already have complete low and high resolution mid-infrared spectra between 5 microns and 35 microns from the Spitzer Infrared Spectrograph, and which also have spectral energy distributions (SEDs) from IRAS and Akari photometry. [CII] 158 um is the strongest far-infrared emission line and therefore crucial to compare with other features in luminous, dusty galaxies. Sources have 0.004 < z < 0.34 and 43.0 < log L(IR) < 46.8 (erg per sec) and cover the full range of starburst galaxy and AGN classifications. Obtaining these [CII] line fluxes with PACS will allow: 1. determining how precisely [CII] luminosity measures star formation rate by comparing to PAH features and emission lines that arise in starburst galaxies; 2. determining how [CII] luminosity and equivalent width changes with starburst/AGN fraction, by comparing with strength and equivalent width of PAH and [NeII] emission arising from starbursts, and with strength of high ionization lines [NeV] and [OIV] and silicate absorption or emission arising from AGN; 3. determining how [CII] luminosity and equivalent width changes with dust temperature and bolometric luminosity, as derived from spectral energy distributions, and whether this depends on the starburst/AGN fraction. These determinations will allow interpretation of high redshift sources for which the only available diagnostics are the luminosity and equivalent width of the [CII] line and the far-infrared rest-frame SED. The total observing program requires 20.2 hours of Herschel observing time.

  1. X-ray observations of highly obscured τ9.7 μm > 1 sources: an efficient method for selecting Compton-thick AGN?

    NASA Astrophysics Data System (ADS)

    Georgantopoulos, I.; Dasyra, K. M.; Rovilos, E.; Pope, A.; Wu, Y.; Dickinson, M.; Comastri, A.; Gilli, R.; Elbaz, D.; Armus, L.; Akylas, A.

    2011-07-01

    Observations with the IRS spectrograph onboard Spitzer have found many sources with very deep Si features at 9.7 μm, that have optical depths of τ > 1. Since it is believed that a few of these systems in the local Universe are associated with Compton-thick active galactic nuclei (hereafter AGN), we set out to investigate whether the presence of a strong Si absorption feature is a good indicator of a heavily obscured AGN. We compile X-ray spectroscopic observations available in the literature on the optically-thick (τ9.7 μm > 1) sources from the 12 μm IRAS Seyfert sample. We find that the majority of the high-τ optically confirmed Seyferts (six out of nine) in the 12 μm sample are probably Compton-thick. Thus, we provide direct evidence of a connection between mid-IR optically-thick galaxies and Compton-thick AGN, with the success rate being close to 70% in the local Universe. This is at least comparable to, if not better than, other rates obtained with photometric information in the mid to far-IR, or even mid-IR to X-rays. However, this technique cannot provide complete Compton-thick AGN samples, i.e., there are many Compton-thick AGN that do not display significant Si absorption, with the most notable example being NGC 1068. After assessing the validity of the high 9.7 μm optical-depth technique in the local Universe, we attempt to construct a sample of candidate Compton-thick AGN at higher redshifts. We compile a sample of seven high-τSpitzer sources in the Great Observatories Origins Deep Survey (GOODS) and five in the Spitzer First-Look Survey. All these have been selected to have no PAH features (EW6.2 μm < 0.3 μm) to maximise the probability that they are bona-fide AGN. Six out of the seven GOODS sources have been detected in X-rays, while for the five FLS sources only X-ray flux upper limits are available. The high X-ray luminosities (LX > 1042 erg s-1) of the detected GOODS sources corroborates that these are AGN. For FLS, ancillary optical

  2. VizieR Online Data Catalog: FIR spectra of AGNs from Herschel (Fernandez-Ontiveros+, 2016)

    NASA Astrophysics Data System (ADS)

    Fernandez-Ontiveros, J. A.; Spinoglio, L.; Pereira-Santaella, M.; Malkan, M. A.; Andreani, P.; Dasyra, K. M.

    2016-11-01

    The combination of Herschel/PACS during its 3.5yr of operational life and Spitzer/IRS allows us to cover the fine-structure emission lines from the mid- to the far-IR (10-200um in the rest-frame) for all the galaxies in the sample. This database was completed with the Herschel/SPIRE published values of the [NII]205um, and [CI]371,609um line fluxes (mainly from Kamenetzky+ 2016ApJ...829...93K). Table 8 collects published mid-IR (10-35um) fine-structure line fluxes measured with Spitzer/IRS for our samples of AGN and starburst galaxies. These values were complemented with unpublished IRS observations from the Spitzer archive. (10 data files).

  3. Linking the central engine to the jet properties in radio loud AGN

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    We explore the connection between the black hole mass and its relativistic jet for a sample of radio-loud AGN (z < 1), in which the relativistic jet parameters are well estimated by means of long term monitoring with the 14m Metsähovi millimeter wave telescope and the Very Long Base-line Array (VLBA). NIR host galaxy images taken with the NOTCam on the Nordic Optical Telescope (NOT) and retrieved from the 2MASS all-sky survey allowed us to perform a detailed surface brightness decomposition of the host galaxies in our sample and to estimate reliable black hole masses via their bulge luminosities. We present early results on the correlations between black hole mass and the relativistic jet parameters. Our preliminary results suggest that the more massive the black hole is, the faster and the more luminous jet it produces.

  4. 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

  5. VizieR Online Data Catalog: AGN in nearby low-mass galaxies (Sartori+, 2015)

    NASA Astrophysics Data System (ADS)

    Sartori, L. F.; Schawinski, K.; Treister, E.; Trakhtenbrot, B.; Koss, M.; Shirazi, M.; Oh, K.

    2016-07-01

    We assembled a sample of nearby dwarf galaxies in the SDSS DR7 (Abazajian et al., 2009ApJS..182..543A) starting from the OSSY catalogue (Oh-Sarzi-Schawinski-Yi; Oh et al., 2011ApJS..195...13O). The OSSY catalogue provides line measurements for the entire spectral atlas from SDSS DR7 with redshift z<0.2, as well as fitting quality assessment parameters.2 We selected the objects in the catalogue with SDSS SpecClass=2 (galaxy) and redshift lower than z=0.1. We then matched the sample to the MPA-JHU catalogue (Kauffmann et al., 2003MNRAS.341...33K; Brinchmann et al., 2004MNRAS.351.1151B) to obtain the stellar mass, and selected the galaxies with mass lower than M*=109.5M⊙. These masses were derived using fits to photometry and assuming h=0.7. We further excluded 0.17 per cent of the objects because of unreliable mass estimation. The final sample of nearby dwarf galaxies consists of 48416 objects. We searched for AGN in the nearby dwarf galaxy sample by applying three AGN selection techniques: 1. classical BPT selection (optical emission line diagnostic) based on the separation lines defined by Kewley et al. (2001ApJ...556..121K), Kauffmann et al. (2003MNRAS.346.1055K) and Schawinski et al. (2007MNRAS.382.1415S); 2. the emission line diagnostic based on HeII λ4686 described by Shirazi & Brinchmann (2012MNRAS.421.1043S) (in the following Shirazi HeII diagram); and 3. the mid-IR colour criteria described by Stern et al. (2012ApJ...753...30S) and Jarrett et al. (2011ApJ...735..112J). (7 data files).

  6. The VIMOS Public Extragalactic Redshift Survey (VIPERS). A support vector machine classification of galaxies, stars, and AGNs

    NASA Astrophysics Data System (ADS)

    Małek, K.; Solarz, A.; Pollo, A.; Fritz, A.; Garilli, B.; Scodeggio, M.; Iovino, A.; Granett, B. R.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bolzonella, M.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Guzzo, L.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fevre, O.; Maccagni, D.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.; Zamorani, G.

    2013-09-01

    Aims: The aim of this work is to develop a comprehensive method for classifying sources in large sky surveys and to apply the techniques to the VIMOS Public Extragalactic Redshift Survey (VIPERS). Using the optical (u∗,g',r',i') and near-infrared (NIR) data (z', Ks), we develop a classifier, based on broad-band photometry, for identifying stars, active galactic nuclei (AGNs), and galaxies, thereby improving the purity of the VIPERS sample. Methods: Support vector machine (SVM) supervised learning algorithms allow the automatic classification of objects into two or more classes based on a multidimensional parameter space. In this work, we tailored the SVM to classifying stars, AGNs, and galaxies and applied this classification to the VIPERS data. We trained the SVM using spectroscopically confirmed sources from the VIPERS and VVDS surveys. Results: We tested two SVM classifiers and concluded that including NIR data can significantly improve the efficiency of the classifier. The self-check of the best optical + NIR classifier has shown 97% accuracy in the classification of galaxies, 97% for stars, and 95% for AGNs in the 5-dimensional colour space. In the test of VIPERS sources with 99% redshift confidence, the classifier gives an accuracy equal to 94% for galaxies, 93% for stars, and 82% for AGNs. The method was applied to sources with low-quality spectra to verify their classification, hence increasing the security of measurements for almost 4900 objects. Conclusions: We conclude that the SVM algorithm trained on a carefully selected sample of galaxies, AGNs, and stars outperforms simple colour-colour selection methods and can be regarded as a very efficient classification method particularly suitable for modern large surveys. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programme 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint

  7. The first experiment of accretion disc tomography in AGNs

    NASA Astrophysics Data System (ADS)

    Risaliti, Guido

    2011-10-01

    We propose four one-orbit observations of the AGN in NGC~1365, with the main aim of measuring the spectral variations during an eclipse. This source showed extraordinary variability in the past observations, indicating a high probability of catching an eclipse by a Compton-thick cloud in the proposed observation time. The differences in the shape of the iron broad emission line at different phases of the eclipse would be a decisive proof of the relativistic effects on this line due to the strong gravity and fast orbital motion of the inner part of the accretion disc. In addition to this unique experiment, the spectral complexity of NGC~1365 (with the highest S/N detection of iron absorption lines in AGNs) makes it the ideal target for a deep ``legacy'' observation.

  8. NGC 741: Mergers and AGN feedback at the group scale

    NASA Astrophysics Data System (ADS)

    Vrtilek, Jan

    2014-09-01

    While AGN and mergers are thought to play important roles in group and cluster evolution, their effects in galaxy groups are poorly understood. We propose to observe the NGC 741 group, which hosts both an old central radio galaxy, and a spectacular infalling head-tail source. Strongly-bent jets, a 100kpc radio trail and intriguing narrow X-ray filaments suggest that NGC 742 is moving trans-sonically, undergoing stripping and shock heating. NGC 741 possesses both an old, faint radio lobe and an X-ray cavity, whose inflating plasma may have unusual properties. We request Chandra and XMM observations of the group with the goal of examining the roles of the central AGN and infalling galaxy in heating the intra-group medium, and determining the origin of the intriguing X-ray filaments.

  9. Extending virial black hole mass estimates to low-luminosity or obscured AGN: the cases of NGC 4395 and MCG -01-24-012

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    In the last decade, using single epoch (SE) virial based spectroscopic optical observations, it has been possible to measure the black hole (BH) mass on large type 1 active galactic nuclei (AGN) samples. However this kind of measurements cannot be applied on those obscured type 2 and/or low-luminosity AGN where the nuclear component does not dominate in the optical. We have derived new SE relationships, based on the full width at half-maximum and luminosity of the broad-line region component of the Paβ emission line and/or the hard X-ray luminosity in the 14-195 keV band, which have the prospect of better working with low luminosity or obscured AGN. The SE relationships have been calibrated in the 105-109 M⊙ mass range, using a sample of AGN, whose BH masses have been previously measured using reverberation mapping techniques. Our tightest relationship between the reverberation-based BH mass and the SE virial product has an intrinsic spread of 0.20 dex. Thanks to these SE relations, in agreement with previous estimates, we have measured a BH mass of M_BH = 1.7^{+1.3}_{-0.7} × 10^5 M⊙ for the low luminosity, type 1, AGN NGC 4395 (one of the smallest active galactic BH known). We also measured, for the first time, a BH mass of M_BH = 1.5^{+1.1}_{-0.6} × 10^7 M⊙ for the Seyfert 2 galaxy MCG -01-24-012.

  10. BAT AGN Spectroscopic Survey - IV: Near-Infrared Coronal Lines, Hidden Broad Lines, and Correlation with Hard X-ray Emission

    NASA Astrophysics Data System (ADS)

    Lamperti, Isabella; Koss, Michael; Trakhtenbrot, Benny; Schawinski, Kevin; Ricci, Claudio; Oh, Kyuseok; Landt, Hermine; Riffel, Rogério; Rodríguez-Ardila, Alberto; Gehrels, Neil; Harrison, Fiona; Masetti, Nicola; Mushotzky, Richard; Treister, Ezequiel; Ueda, Yoshihiro; Veilleux, Sylvain

    2017-01-01

    We provide a comprehensive census of the near-Infrared (NIR, 0.8-2.4 μm) spectroscopic properties of 102 nearby (z < 0.075) active galactic nuclei (AGN), selected in the hard X-ray band (14-195 keV) from the Swift-Burst Alert Telescope (BAT) survey. With the launch of the James Webb Space Telescope this regime is of increasing importance for dusty and obscured AGN surveys. We measure black hole masses in 68% (69/102) of the sample using broad emission lines (34/102) and/or the velocity dispersion of the Ca II triplet or the CO band-heads (46/102). We find that emission line diagnostics in the NIR are ineffective at identifying bright, nearby AGN galaxies because ([Fe II] 1.257μm/Paβ and H2 2.12μm/Brγ) identify only 25% (25/102) as AGN with significant overlap with star forming galaxies and only 20% of Seyfert 2 have detected coronal lines (6/30). We measure the coronal line emission in Seyfert 2 to be weaker than in Seyfert 1 of the same bolometric luminosity suggesting obscuration by the nuclear torus. We find that the correlation between the hard X-ray and the [Fe II] coronal line luminosity is significantly better than with the [O III] λ5007 luminosity. Finally, we find 3/29 galaxies (10%) that are optically classified as Seyfert 2 show broad emission lines in the NIR. These AGN have the lowest levels of obscuration among the Seyfert 2s in our sample (log NH < 22.43 cm-2), and all show signs of galaxy-scale interactions or mergers suggesting that the optical broad emission lines are obscured by host galaxy dust.

  11. The AT20G view of Swift/BAT selected AGN: high-frequency radio waves meet hard X-rays

    NASA Astrophysics Data System (ADS)

    Burlon, D.; Ghirlanda, G.; Murphy, T.; Chhetri, R.; Sadler, E.; Ajello, M.

    2013-05-01

    We cross-matched the 6-year Swift/Burst Alert Telescope (BAT) survey of active galactic nuclei (AGN) with the AT20G radio survey of the southern sky, which is one of the largest high-frequency radio surveys available. With these data we investigated the possible correlation between the radio and the X-ray emission at the highest radio and X-ray frequencies. We found 37 AGN with a high probability of association (>80 per cent), among which 19 are local Seyfert galaxies (with median redshift z = 0.03) and 18 blazars. We found that ≈20 per cent of the AGN detected in hard X-rays are also bright radio sources at 20 GHz, but the apparent correlation between the radio and hard X-ray luminosity is completely driven by the different median redshifts of the two subgroups of AGN. When we consider only the local Seyfert sample we find no evidence of a correlation between their 20 GHz and 15-55 keV power. Therefore it appears that at high frequencies the radio-X connection, which had been previously observed at lower frequencies, disappears. The disappearance of the radio-X correlation at high radio and X-ray frequencies could be tested through Very Long Baseline Interferometry and the use of the Nuclear Spectroscopic Telescope Array (NuSTAR) satellite.

  12. Announcment: Conference on Obscured AGN Across Cosmic Time

    NASA Astrophysics Data System (ADS)

    2006-12-01

    Current deep surveys, notably in X-rays and the mid-IR, are making it possible to carry out a census of essentially all the luminous AGN in the Universe. By pene-trating the obscuration that, in Type 2 sources, hides the nuclear regions in the UV to the near-IR spectrum, these new surveys are finding the radio quiet coun-terparts of the powerful radio galaxies.

  13. The international AGN watch: A multiwavelength monitoring consortium

    NASA Technical Reports Server (NTRS)

    Alloin, D.; Clavel, J.; Peterson, B. M.; Reichert, G. A.; Stirpe, G. M.

    1994-01-01

    The International AGN Watch, an informal consortium of over 100 astronomers, was established to coordinate multiwavelength monitoring of a limited number of active galactic nuclei and thus obtain comprehensive continuum and emission-line variability data with unprecedented temporal and wavelength coverage. We summarize the principal scientific results from two completed space-based and ground-based campaigns on the Seyfert galaxies NGC 5548 and NGC 3783. We describe a project in progress and outline our future plans.

  14. 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.

  15. Investigating the AGN activity and black hole masses in low surface brightness galaxies

    NASA Astrophysics Data System (ADS)

    Subramanian, Smitha; Sethuram, Ramya; Das, Mousumi; George, Koshy; Thirupathi, Sivarani; Prabhu, Tushar P.

    2016-02-01

    We present an analysis of the optical nuclear spectra from the active galactic nuclei (AGN) in a sample of giant low surface brightness (GLSB) galaxies. GLSB galaxies are extreme late type spirals that are large, isolated and poorly evolved compared to regular spiral galaxies. Earlier studies have indicated that their nuclei have relatively low mass black holes. Using data from the Sloan Digital Sky Survey (SDSS), we selected a sample of 30 GLSB galaxies that showed broad Hα emission lines in their AGN spectra. In some galaxies such as UGC 6284, the broad component of Hα is more related to outflows rather than the black hole. One galaxy (UGC 6614) showed two broad components in Hα, one associated with the black hole and the other associated with an outflow event. We derived the nuclear black hole (BH) masses of 29 galaxies from their broad Hα parameters. We find that the nuclear BH masses lie in the range 105 - 107 M⊙. The bulge stellar velocity dispersion σ e was determined from the underlying stellar spectra. We compared our results with the existing BH mass - velocity dispersion (M BH-σ e ) correlations and found that the majority of our sample lie in the low BH mass regime and below the M BH-σ e correlation. The effects of galaxy orientation in the measurement of σ e and the increase of σ e due to the effects of bar are probable reasons for the observed offset for some galaxies, but in many galaxies the offset is real. A possible explanation for the M BH-σ e offset could be lack of mergers and accretion events in the history of these galaxies which leads to a lack of BH-bulge co-evolution.

  16. 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.

  17. Compton Reflection in AGN with Simbol-X

    NASA Astrophysics Data System (ADS)

    Beckmann, V.; Courvoisier, T. J.-L.; Gehrels, N.; Lubiński, P.; Malzac, J.; Petrucci, P. O.; Shrader, C. R.; Soldi, S.

    2009-05-01

    AGN exhibit complex hard X-ray spectra. Our current understanding is that the emission is dominated by inverse Compton processes which take place in the corona above the accretion disk, and that absorption and reflection in a distant absorber play a major role. These processes can be directly observed through the shape of the continuum, the Compton reflection hump around 30 keV, and the iron fluorescence line at 6.4 keV. We demonstrate the capabilities of Simbol-X to constrain complex models for cases like MCG-05-23-016, NGC 4151, NGC 2110, and NGC 4051 in short (10 ksec) observations. We compare the simulations with recent observations on these sources by INTEGRAL, Swift and Suzaku. Constraining reflection models for AGN with Simbol-X will help us to get a clear view of the processes and geometry near to the central engine in AGN, and will give insight to which sources are responsible for the Cosmic X-ray background at energies >20 keV.

  18. Clustering, Cosmology and a New Era of Black Hole Demographics: The Conditional Luminosity Function of AGNs

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2016-04-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of AGN evolution stretching back to z˜5. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, we present a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific z. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function - all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method is demonstrated at z ≈0 and 0.9, and clear luminosity dependence in the AGN bias and mean halo mass is predicted at both z. The results support the idea that there are at least two different modes of AGN triggering: one, at high luminosity, that only occurs in high mass, highly biased haloes, and one that can occur over a wide range of halo masses and leads to luminosities that are correlated with halo mass. This latter mode dominates at z<0.9. The CLFs for Type 2 and Type 1 AGNs are also constrained at z ≈0, and we find evidence that unobscured quasars are more likely to be found in higher mass halos than obscured quasars. Thus, the AGN unification model seems to fail at quasar luminosities.

  19. 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).

  20. Investigating the host galaxies of luminous AGN in the local universe with integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    McElroy, Rebecca; Croom, Scott; Husemann, Bernd; Close AGN Reference Survey; SAMI Galaxy Survey

    2017-01-01

    This thesis investigates how galaxies and their super massive black holes coevolve. We use integral field spectroscopy to search for evidence of AGN feedback and triggering. We demonstrate that outflows are ubiquitous among luminous local type 2 AGN using observations from the AAT's SPIRAL instrument. Using multiple component Gaussian emission line decomposition we are able to disentangle the kinematic and ionisation properties of these winds. This allows us to argue that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies. We search for evidence of AGN triggering using data from The Close AGN Reference Survey (CARS). CARS aims to provide a detailed multi-wavelength view of 40 nearby (0.01 < z < 0.06) unobscured AGN to study the link between AGN and their host galaxies. The primary CARS observations come from the MUSE integral field unit on the VLT, and complementary multi-wavelength observations have been approved from SOFIA, Chandra, VLA, HST, and others. We compare the stellar kinematics of active galaxies from CARS to similar inactive galaxies. We then use kinemetry to estimate the degree of dynamical disturbance, to determine whether active nuclei are preferentially hosted in dynamically disturbed or merging systems. Finally, we highlight the discovery of an AGN that has changed spectral type not once, but twice. So called ‘changing look’ AGN are an uncommon phenomenon, but twice changed AGN are much rarer. This AGN first transitioned from a narrow line AGN (type 2) to a broad line AGN (type 1) in the 1980s. It was recently observed as part of CARS. Examination of the MUSE data for this particular source showed that it no longer had the spectral features typical of a type 1 AGN. The continuum emission from the accretion disk was no longer visible and the broad lines were dramatically diminished. In this talk we describe the possible reasons for this change, supported by analysis of multi-epoch optical photometry and

  1. Constraining Feedback in Galaxy Formation: Using Galaxy and AGN Surveys to Shed Light on ``Gastrophysics"

    NASA Astrophysics Data System (ADS)

    Monaco, P.

    2007-12-01

    We present some results of the new MORGANA model for the rise of galaxies and active nuclei, and show that the improved physical motivation of the description of star formation and feedback allows to get hints on the physical processes at play. We propose that the high level of turbulence in star-forming bulges is at the base of the observed downsizing of AGNs. In this framework it is also possible to reproduce the recently obtained evidence that most low-redshift accretion is powered by relatively massive, slowly accreting black holes. Besides, we notice that many galaxy formation models (including MORGANA) fail to reproduce a basic observable, namely the number density of 10^{11} M_⊙ galaxies at z˜1, as traced by the GOODS-MUSIC sample. This points to a possibly missing ingredient in the modeling of stellar feedback.

  2. SDSS-RM: A Multi-Object AGN Reverberation Mapping Project

    NASA Astrophysics Data System (ADS)

    Shen, Y.; SDSS-RM Collaboration

    2016-10-01

    The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project is a dedicated multi-object RM program that simultaneously monitors ˜ 850 quasars at 0.1< z <4.5 with imaging and spectroscopy in order to measure RM lags for a homogeneous AGN sample. The combination of multi-year, high-cadence photometric light curves since 2010 (hundreds of epochs) and dedicated SDSS spectroscopy (32 epochs completed in 2014 with more epochs in 2015 and beyond) will enable important studies on the structure of the broad-line region (BLR), RM lags and BH mass measurements, as well as ancillary science such as quasar variability, host galaxy properties, and quasar absorption lines. I will summarize the current status of the program and present some early science results based on the year-1 SDSS-RM data.

  3. AGN Diagnostic Plot In The WISE And 3XMM Era: The Role Of Variability

    NASA Astrophysics Data System (ADS)

    Zaino, Alessandra; Severgnini, P.; Vignali, C.; Della Ceca, R.; Ballo, L.

    2016-10-01

    An efficient diagnostic method to find local (z<0.1) Compton-thick AGN consists in selecting sources characterized by hard X- ray colors and low hard X-ray over mid-IR flux ratio. This has been done efficiently in the past using 2XMM and IRAS data (Severgnini et al. 2012). In this talk I will present my thesis work in which I tested this technique using the latest 3XMM and WISE data for the sample presented by Severgnini et al. I will also briefly discuss the X-ray spectral properties of all of those sources showing flux and/or spectral variability in the XMM-Newton observations.

  4. Links Between Emission Line Properties of AGN and Their X-ray SED Components

    NASA Astrophysics Data System (ADS)

    Ward, Martin; Done, C.; Gelbord, J.; Hutton, S.; Jin, C.

    2010-03-01

    We have produced SEDs from 1 micron to 10keV, for a sample of about 50 AGN based on observations with XMM-Newton, including UV points from the optical monitor, and the SDSS. Using detailed spectral fitting techniques, we quantify the contributions from an accretion disc, a hot Compton component, and a power-law, including the effects of absorption. From the optical spectra we measure the principal emission line diagnostics of conditions within the BLR, NLR and the highly ionised regions. By our decomposition of the X-ray to optical continuum into its constituent components, and using correlations with the optical emission lines, we are able to identify the strongest links. From this understanding of how emission lines respond to the separate components of the ionising continuum, we can better explain the wide range of properties from narrowest line Seyfert 1s up to those displaying exceptionally broad emission lines.

  5. 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.

  6. 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.

  7. Search for Gamma-ray-emitting Active Galactic Nuclei in the Fermi-LAT Unassociated Sample Using Machine Learning

    NASA Astrophysics Data System (ADS)

    Doert, M.; Errando, M.

    2014-02-01

    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.

  8. 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.

  9. Clustering, Cosmology and a New Era of Black Hole Demographics: The Conditional Luminosity Function of AGNs

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2017-01-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of active galactic nuclei (AGN) evolution stretching back to z~5. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, we present a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific z. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function -- all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method is illustrated at z≈0 and 0.9 using the limited data that is currently available, and a clear luminosity dependence in the AGN bias and mean halo mass is predicted at both, supporting the idea that there are at least two different modes of AGN triggering. In addition, the CLF predicts that z≈0.9 quasars may be commonly hosted by haloes with Mh ~ 1014 M⊙. These `young cluster' environments may provide the necessary interactions between gas-rich galaxies to fuel luminous accretion. The results derived from this method will be useful to populate AGNs of different luminosities in cosmological simulations.

  10. Incidence of WISE -selected obscured AGNs in major mergers and interactions from the SDSS

    NASA Astrophysics Data System (ADS)

    Weston, Madalyn E.; McIntosh, Daniel H.; Brodwin, Mark; Mann, Justin; Cooper, Andrew; McConnell, Adam; Nielsen, Jennifer L.

    2017-02-01

    We use the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS) to confirm a connection between dust-obscured active galactic nuclei (AGNs) and galaxy merging. Using a new, volume-limited (z ≤ 0.08) catalogue of visually selected major mergers and galaxy-galaxy interactions from the SDSS, with stellar masses above 2 × 1010 M⊙, we find that major mergers (interactions) are 5-17 (3-5) times more likely to have red [3.4] - [4.6] colours associated with dust-obscured or `dusty' AGNs, compared to non-merging galaxies with similar masses. Using published fibre spectral diagnostics, we map the [3.4] - [4.6] versus [4.6] - [12] colours of different emission-line galaxies and find that one-quarter of Seyferts have colours indicative of a dusty AGN. We find that AGNs are five times more likely to be obscured when hosted by a merging galaxy, half of AGNs hosted by a merger are dusty, and we find no enhanced frequency of optical AGNs in merging over non-merging galaxies. We conclude that undetected AGNs missed at shorter wavelengths are at the heart of the ongoing AGN-merger connection debate. The vast majority of mergers hosting dusty AGNs are star forming and located at the centres of Mhalo < 1013 M⊙ groups. Assuming plausibly short-duration dusty-AGN phases, we speculate that a large fraction of gas-rich mergers experience a brief obscured AGN phase, in agreement with the strong connection between central star formation and black hole growth seen in merger simulations.

  11. Herschel far-infrared photometry of the Swift Burst Alert Telescope active galactic nuclei sample of the local universe - III. Global star-forming properties and the lack of a connection to nuclear activity

    NASA Astrophysics Data System (ADS)

    Shimizu, T. Taro; Mushotzky, Richard F.; Meléndez, Marcio; Koss, Michael J.; Barger, Amy J.; Cowie, Lennox L.

    2017-04-01

    We combine the Herschel Space Observatory PACS (Photoconductor Array Camera and Spectrometer) and SPIRE (Spectral and Photometric Imaging Receiver) photometry with archival WISE (Wide-field Infrared Survey Explorer) photometry to construct the spectral energy distributions (SEDs) for over 300 local (z < 0.05), ultrahard X-ray (14-195 keV) selected active galactic nuclei (AGN) from the Swift Burst Alert Telescope (BAT) 58-month catalogue. Using a simple analytical model that combines an exponentially cutoff power law with a single temperature modified blackbody, we decompose the SEDs into a host galaxy and AGN component. We calculate dust masses, dust temperatures, and star formation rates (SFRs) for our entire sample and compare them to a stellar mass-matched sample of local non-AGN galaxies. We find AGN host galaxies have systematically higher dust masses, dust temperatures, and SFRs due to the higher prevalence of late-type galaxies to host an AGN, in agreement with previous studies of the Swift/BAT AGN. We provide a scaling to convert X-ray luminosities into 8-1000 μm AGN luminosities, as well as determine the best mid-to-far IR colours for identifying AGN-dominated galaxies in the IR regime. We find that for nearly 30 per cent of our sample, the 70 μm emission contains a significant contribution from the AGN (>0.5), especially at higher luminosities (L14 - 195 keV > 1042.5 erg s-1). Finally, we measure the local SFR-AGN luminosity relationship, finding a slope of 0.18, large scatter (0.37 dex), and no evidence for an upturn at high AGN luminosity. We conclude with a discussion on the implications of our results within the context of galaxy evolution with and without AGN feedback.

  12. F-Gamma program: Probing the AGN physics via broad-band radio variability studies

    NASA Astrophysics Data System (ADS)

    Schmidt, Rebekka

    2011-07-01

    The F-GAMMA program (Fermi-GST AGN Multi-frequency Monitoring Alliance) is meant to investigate the physics of AGNs via a multi-frequency monitoring approach. Blazars are AGNs that show intense variability in flux and polarisation and super-luminal motions due to small viewing angles to the jet axis. Hence, there is very extreme physics at work and despite decades of study the exact physics are still unclear. A method to distinguish between different emission models are the multi-frequency variability studies. The Fermi-GST scans the entire sky every three hours. So, for the first time it provides densely sampled gamma-ray light curves which can be cross-correlated with radio, optical or other light curves. To fully exploit these features 65 Fermi-GST detectable blazars are being monitored monthly in radio wavelength since 2007. The core program involves observations with the 100-m Effelsberg telescope at 8 frequencies between 2.6 and 43 GHz, the 30-m IRAM telescope at 86, 145 and 240 GHz and the APEX 12-m telescope at 345 GHz. Spectra simultaneous within a week are produced for cross-band studies. In this talk results of time series analysis studies will be presented in an attempt to search for characteristic timescales and study the brightness temperatures and variability Doppler factors of these objects. Furthermore, it will be shown that all the spectra can be grouped in only 9 phenomenological classes of spectral variability pattern. Seven of these classes are clearly dominated by spectral evolution and can be interpreted as a quiescent optically thin spectrum with a super-imposed flaring event. The different classes can be explained by different redshifts and intrinsic-source/flare parameters as simulations showed. The other 2 classes vary self-similarly with almost no apparent shift of the peak frequency implying that a totally different mechanism is at work. From all this it is concluded that only two mechanisms have been observed to produce variability

  13. The Spiral Structure of AGN Host Galaxies

    NASA Astrophysics Data System (ADS)

    Kennefick, J.; Barrows, R. S.; Hughes, J. A.; Schilling, A.; Davis, B.; Shields, D.; Madey, A.; Kennefick, D.; Lacy, C.; Seigar, M.

    2014-03-01

    Recent work has uncovered a correlation between the black hole mass, M, in the centers of local spiral galaxies and the pitch angles, P, of their spiral arms. We propose to test this M-P correlation at moderate to high redshifts, using a sample of active galaxies selected from the Great Observatories Origins Survey and the Sloan Digital Sky Survey showing evidence for spiral structure in their host galaxies. The mass of the central black holes are estimated using the Hβ or Mg II lines in existing spectra using luminosity-radius scaling relations. Pitch angles are measured using an iterative 2D FFT algorithm. The aim is to establish this M-P relation beyond our local epoch, test for evolution in its form, and eventually to compute a BH mass function for late-type galaxies out to moderate redshifts.

  14. 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.

  15. On the relation between X-ray absorption and optical extinction in AGN

    NASA Astrophysics Data System (ADS)

    Ordovás-Pascual, I.; Mateos, S.; Carrera, F. J.; Wiersema, K.; Caccianiga, A.; Della Ceca, R.; Severgnini, P.; Moretti, A.; Ballo, L.

    2017-03-01

    According to the Unified Model of Active Galactic Nuclei (AGN), an X-ray unabsorbed AGN should appear as unobscured in the optical band (the so called type-1 AGN). 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 types of analysis: 1) a detailed study of the UV-to-near-IR emission of two X-ray low absorbed AGN with high optical extinction 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. We have determined the impact of contamination from the AGN hosts in their optical classification (detection or lack of detection of rest-frame UV-optical broad emission lines). This is an on-going project, but our preliminary results, reported below, are very promising.

  16. Unravelling the Complex Structure of AGN-driven Outflows. II. Photoionization and Energetics

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Outflows have been shown to be prevalent in galaxies hosting luminous active galactic nuclei (AGNs); they present a physically plausible way to couple the AGN energy output with the interstellar medium of their hosts. Despite their prevalence, accurate characterization of these outflows has been challenging. In the second of a series of papers, we use Gemini Multi-Object Spectrograph integral field unit (IFU) data of six local (z < 0.1) and moderate-luminosity Type 2 AGNs to study the ionization properties and energetics of AGN-driven outflows. We find strong evidence connecting the extreme kinematics of the ionized gas to the AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as virial motions or rotation, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that 30 to 90% of the total mass and kinetic energy of the outflow is contained within the central kpc of the galaxy. The spatially integrated mass and kinetic energy of the gas entrained in the outflow correlate well with the AGN bolometric luminosity and results in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of galaxy-scale negative feedback.

  17. 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.

  18. A Search for AGN Intra-Day Variability with KVN

    NASA Astrophysics Data System (ADS)

    Lee, Taeseok; Trippe, Sascha; Oh, Junghwan; Byun, Do-Young; Sohn, Bong-Won; Lee, Sang-Sung

    2015-10-01

    Active galactic nuclei (AGN) are known for irregular variability on all time scales, down to intra-day variability with relative variations of a few percent within minutes to hours. On such short timescales, unexplored territory, such as the possible existence of a shortest characteristic time scale of activity and the shape of the high frequency end of AGN power spectra, still exists. We present the results of AGN single-dish fast photometry performed with the Korean VLBI Network (KVN). Observations were done in a "anti-correlated" mode using two antennas, with always at least one antenna pointing at the target. This results in an effective time resolution of less than three minutes. We used all four KVN frequencies, 22, 43, 86, and 129 GHz, in order to trace spectral variability, if any. We were able to derive high-quality light curves for 3C 111, 3C 454.3, and BL Lacertae at 22 and 43 GHz, and for 3C 279 at 86 GHz, between May 2012 and April 2013. We performed a detailed statistical analysis in order to assess the levels of variability and the corresponding upper limits. We found upper limits on flux variability ranging from ∼1.6% to ∼7.6%. The upper limits on the derived brightness temperatures exceed the inverse Compton limit by three to six orders of magnitude. From our results, plus comparison with data obtained by the University of Michigan Radio Astronomy Observatory, we conclude that we have not detected source-intrinsic variability which would have to occur at sub-per cent levels.

  19. Relativistic HD and MHD modelling for AGN jets

    NASA Astrophysics Data System (ADS)

    Keppens, R.; Porth, O.; Monceau-Baroux, R.; Walg, S.

    2013-12-01

    Relativistic hydro and magnetohydrodynamics (MHD) provide a continuum fluid description for plasma dynamics characterized by shock-dominated flows approaching the speed of light. Significant progress in its numerical modelling emerged in the last two decades; we highlight selected examples of modern grid-adaptive, massively parallel simulations realized by our open-source software MPI-AMRVAC (Keppens et al 2012 J. Comput. Phys. 231 718). Hydrodynamical models quantify how energy transfer from active galactic nuclei (AGN) jets to their surrounding interstellar/intergalactic medium (ISM/IGM) gets mediated through shocks and various fluid instability mechanisms (Monceau-Baroux et al 2012 Astron. Astrophys. 545 A62). With jet parameters representative for Fanaroff-Riley type-II jets with finite opening angles, we can quantify the ISM volumes affected by jet injection and distinguish the roles of mixing versus shock-heating in cocoon regions. This provides insight in energy feedback by AGN jets, usually incorporated parametrically in cosmological evolution scenarios. We discuss recent axisymmetric studies up to full 3D simulations for precessing relativistic jets, where synthetic radio maps can confront observations. While relativistic hydrodynamic models allow one to better constrain dynamical parameters like the Lorentz factor and density contrast between jets and their surroundings, the role of magnetic fields in AGN jet dynamics and propagation characteristics needs full relativistic MHD treatments. Then, we can demonstrate the collimating properties of an overal helical magnetic field backbone and study differences between poloidal versus toroidal field dominated scenarios (Keppens et al 2008 Astron. Astrophys. 486 663). Full 3D simulations allow one to consider the fate of non-axisymmetric perturbations on relativistic jet propagation from rotating magnetospheres (Porth 2013 Mon. Not. R. Astron. Soc. 429 2482). Self-stabilization mechanisms related to the detailed

  20. The AGN Jet Model of the Fermi Bubbles

    NASA Astrophysics Data System (ADS)

    Guo, Fulai

    2017-01-01

    The nature and origin of the Fermi bubbles detected in the inner Galaxy remain elusive. In this paper, we briefly discuss some recent theoretical and observational developments, with a focus on the AGN jet model. Analogous to radio lobes observed in massive galaxies, the Fermi bubbles could be naturally produced by a pair of opposing jets emanating nearly along the Galaxy's rotation axis from the Galactic center. Our two-fluid hydrodynamic simulations reproduce quite well the bubble location and shape, and interface instabilities at the bubble surface could be effectively suppressed by shear viscosity. We briefly comment on some potential issues related to our model, which may lead to future progress.

  1. Characterizing X-ray Variability Processes in AGN

    NASA Astrophysics Data System (ADS)

    Markowitz, A.

    2006-07-01

    We comment on searches for characteristic X-ray variability time- scales in the red-noise light curves of Active Galactic Nuclei (AGN). Methods for identification of such features and determining their statistical significance are di