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Sample records for agn sample lbas

  1. Extending the Fermi - Swift Joint AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.; Macomb, D. J.

    2014-01-01

    The Swift BAT and the Fermi LAT each provide excellent sky coverage and have led to impressive compilations of extragalactic source catalogs. For the most part they sample separate AGN subpopulations - Swift the lower-luminosity and relatively nearby Seyfert galaxies while the Fermi sample is dominated by blazars and does not include any radio-quiet objects. The overlap between these samples is among the radio-loud subset of the Swift sample as has been discussed elsewhere in the literature. The observable properties at these two bands - flux and spectral indices - are not expected to be well correlated as they sample different portions of the synchrotron self-Compton (SSC) spectral energy distribution. In this contribution we consider an extension of the high-latitude Swift sample by relaxing the significance cut to less than 5 standard deviations and consider the overlap of that subsample with the Fermi AGN catalog. While such a threshold is generally inadvisable as it introduces the strong possibility of spurious detections, the objects of the overlapping sample which are detected at high significance in Fermi can be considered as reasonably high-confidence Swift detections. For example, there are 190 Swift sub-5-sigma Swift sources that have significance >2-sigma with Fermi counterparts, whereas we predict only ~5 due to statistical fluctuation. We also investigate any coincident INTEGRAL/IBIS observations to further bolster or diminish candidate Swift detections. We present our correlation analyses and offer interpretation in the context of the blazar sequence.

  2. MERGING AND CLUSTERING OF THE SWIFT BAT AGN SAMPLE

    SciTech Connect

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

    2010-06-20

    We discuss the merger rate, close galaxy environment, and clustering on scales up to an Mpc of the Swift BAT hard X-ray sample of nearby (z<0.05), moderate-luminosity active galactic nuclei (AGNs). We find a higher incidence of galaxies with signs of disruption compared to a matched control sample (18% versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a larger fraction with companions compared to normal galaxies and optical emission line selected AGNs at scales up to 250 kpc. We hypothesize that these merging AGNs may not be identified using optical emission line diagnostics because of optical extinction and dilution by star formation. In support of this hypothesis, in merging systems we find a higher hard X-ray to [O III] flux ratio, as well as emission line diagnostics characteristic of composite or star-forming galaxies, and a larger IRAS 60 {mu}m to stellar mass ratio.

  3. 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.

  4. X-ray and Optical Properties of an Unbiased Sample of Local AGN

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.; Mushotzky, R.; Tueller, J.; Lewis, K.; Reynolds, C.

    2007-12-01

    The SWIFT Burst Alert Telescope (BAT), while not focused on a Gamma-ray burst, conducts an all-sky survey in the 14 - 195 keV band. After the first 9 months, the BAT has detected a sample of 153 local (z ˜ 0.03) AGN at a flux limit of a few times 10-11 erg/s/cm-2 (Tueller et al. 2007). Since the AGN were detected at very high X-ray energies, they are an unbiased sample towards column densities below 1025 cm-2. We present the X-ray and optical properties of a sample of the BAT AGN.

  5. The nature and origin of Narrow Line AGN activity in a sample of isolated SDSS galaxies

    NASA Astrophysics Data System (ADS)

    Coziol, R.; Torres-Papaqui, J. P.; Plauchu-Frayn, I.; Islas-Islas, J. M.; Ortega-Minakata, R. A.; Neri-Larios, D. M.; Andernach, H.

    2011-10-01

    We discuss the nature and origin of the nuclear activity observed in a sample of 292 SDSS narrow-emission-line galaxies, considered to have formed and evolved in isolation. The fraction of Narrow Line AGNs (NLAGNs) and Transition type Objects (TOs; a NLAGN with circumnuclear star formation) amounts to 64% of the galaxies. We verify that the probability for a galaxy to show an AGN characteristic increases with the bulge mass of the galaxy (Torres-Papaqui et al. 2011), and find evidence that this trend is really a by-product of the morphology, suggesting that the AGN phenomenon is intimately connected with the formation process of the galaxies. The NLAGNs in our sample are consistent with a scaled-down or powered-down versions of quasars and Broad Line AGNs.

  6. Exploring the Variability Characteristics of the Fermi AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2016-04-01

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

  7. A New Sample of Obscured AGNs Selected from the XMM-Newton and AKARI Surveys

    NASA Astrophysics Data System (ADS)

    Terashima, Yuichi; Hirata, Yoshitaka; Awaki, Hisamitsu; Oyabu, Shinki; Gandhi, Poshak; Toba, Yoshiki; Matsuhara, Hideo

    2015-11-01

    We report a new sample of obscured active galactic nuclei (AGNs) selected from the XMM-Newton serendipitous source and AKARI point-source catalogs. We match X-ray sources with infrared (18 and 90 μm) sources located at | b| \\gt 10^\\circ to create a sample consisting of 173 objects. Their optical classifications and absorption column densities measured by X-ray spectra are compiled and study efficient selection criteria to find obscured AGNs. We apply the criteria (1) X-ray hardness ratio defined by using the 2-4.5 keV and 4.5-12 keV bands > -0.1 and (2) EPIC-PN count rate (CR) in the 0.2-12 keV to infrared flux ratio CR/{F}90\\lt 0.1 or CR/{F}18\\lt 1, where F18 and F90 are infrared fluxes at 18 and 90 μm in Jy, respectively, to search for obscured AGNs. X-ray spectra of 48 candidates, for which no X-ray results have been published, are analyzed and X-ray evidence for the presence of obscured AGNs such as a convex shape X-ray spectrum indicative of absorption of {N}{{H}} ˜ 1022-24 cm-2, a very flat continuum, or a strong Fe-K emission line with an equivalent width of \\gt 700 {{eV}} is found in 26 objects. Six of them are classified as Compton-thick AGNs, and four are represented by either Compton-thin or Compton-thick spectral models. The success rate of finding obscured AGNs combining our analysis and the literature is 92% if the 18 μm condition is used. Of the 26 objects, 4 are optically classified as an H ii nucleus and are new “elusive AGNs” in which star formation activity likely overwhelms AGN emission in the optical and infrared bands.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  10. FERMI LAT view of a sample of flaring gamma-ray AGN

    NASA Astrophysics Data System (ADS)

    Buson, S.; Bastieri, D.; D'Ammando, F.; Tosti, G.; Fermi-LAT Collaboration

    2012-12-01

    Radio-loud AGNs, especially blazars, are sources known to be extremely variable over the whole electromagnetic spectrum, from radio to γ-ray energies. Up to now, the Large Area Telescope (LAT), the primary instrument on board the Fermi satellite, has detected more than 850 sources that could be associated with AGNs. Several of them underwent at least one flaring episode at γ-rays during the time spanned by the Fermi observations. We present and discuss a list of flaring AGNs detected during the first 3.5 years of Fermi operations with fluxes brighter than F(E > 100MeV) > 10-6 ph cm-2 s-1, the threshold set by the LAT Collaboration for issuing an Astronomer Telegram. More, the general characteristics of the selected sample are investigated.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  12. Obscured AGN

    NASA Astrophysics Data System (ADS)

    Barger, Amy

    2014-07-01

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

  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. 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.

  15. The Largest X-ray Selected Sample of z > 3 AGNs: C-COSMOS + ChaMPS

    NASA Astrophysics Data System (ADS)

    Kalfountzou, Eleni; Civano, F. M.; Elvis, M.; Trichas, M.

    2014-01-01

    There is strong evidence that powerful active galactic nuclei (AGNs) are important to the evolution of galaxies. AGN evolution at high redshifts, before the density peak, illuminates the role of AGN in the formation and co-evolution of galaxies and their central supermassive black holes (SMBHs) when rapid SMBH growth took place. Optical surveys (e.g. Glikman et al. 2011; Ikeda et al. 2011) are severely biased against obscuration. In contrast, X-ray surveys detect obscured AGNs up to Compton Thick and are now sensitive enough to sample the bulk of the z > 3 AGN population. The few X-ray studies to date suggest a significant decline at z > 3 (e.g. Brusa et al. 2009; Civano et al. 2011; Vito et al; 2012), but the shape of this decline is still uncertain due to the limited sample size, especially at z > 4. To overcome these limits, we combined the two largest samples of z > 3 X-ray selected AGN with spectroscopic redshifts: the Chandra Multi-wavelength Project (ChaMP) survey (Trichas et al. 2012), and the C-COSMOS survey (Civano et al. 2011). The total of 159 z > 3 AGNs almost doubles the sample size and, most importantly, triples the sample at z > 4, where the uncertainties have been greatest. Our sample includes ~35 sources in the low luminosity range [LX < 1044 erg/s] which gives a first determination of their density evolution. Our sample also contains a both obscured and unobscured AGNs, and their separate evolution has been determined.

  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. The largest X-ray-selected sample of z>3 AGNs: C-COSMOS and ChaMP

    NASA Astrophysics Data System (ADS)

    Kalfountzou, E.; Civano, F.; Elvis, M.; Trichas, M.; Green, P.

    2014-12-01

    We present results from an analysis of the largest high-redshift (z > 3) X-ray-selected active galactic nucleus (AGN) sample to date, combining the Chandra Cosmological Evolution Survey and Chandra Multi-wavelength Project surveys and doubling the previous samples. The sample comprises 209 X-ray-detected AGNs, over a wide range of rest-frame 2-10 keV luminosities log LX = 43.3-46.0 erg s-1. X-ray hardness rates show that ˜39 per cent of the sources are highly obscured, NH > 1022 cm-2, in agreement with the ˜37 per cent of type-2 AGNs found in our sample based on their optical classification. For ˜26 per cent of objects have mismatched optical and X-ray classifications. Utilizing the 1/Vmax method, we confirm that the comoving space density of all luminosity ranges of AGNs decreases with redshift above z > 3 and up to z ˜ 7. With a significant sample of AGNs (N = 27) at z > 4, it is found that both source number counts in the 0.5-2 keV band and comoving space density are consistent with the expectation of a luminosity-dependent density evolution (LDDE) model at all redshifts, while they exclude the luminosity and density evolution (LADE) model. The measured comoving space density of type-1 and type-2 AGNs shows a constant ratio between the two types at z > 3. Our results for both AGN types at these redshifts are consistent with the expectations of LDDE model.

  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. X-ray and Optical Properties of an Unbiased, Local ( z ≈ 0.03) AGN Sample Detected by Swift

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.; Mushotzky, R.; Reynolds, C.; Lewis, K.

    2009-01-01

    The Swift Burst Alert Telescope (BAT), while not focused on a Gamma-ray burst, conducts an all-sky survey in the 14 - 195 keV band. After the first 9 months, the BAT has detected a sample of 153 local (z 0.03) AGN at a flux limit of a few times 10-11 erg/s/cm-2 (Tueller et al. 2007). Since the AGN were detected at very high X-ray energies, they are an unbiased sample towards column densities below 1025 cm-2. We present the X-ray and optical properties of a sample of the BAT AGN, including an analysis of the 0.3-10 keV X-ray spectra (Winter et al. 2008) and optical spectra obtained from the literature, SDSS, and our own KPNO 2.1-m observations.

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

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2001-01-01

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

  1. Long-term X-Ray Spectral Variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In 9 of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For 6 objects, with a low accretion rate as a fraction of the Eddington rate (ṁEdd), Γ is anticorrelated with ṁEdd, i.e. `harder-when-brighter' behaviour is observed. The 3 higher-ṁEdd-rate objects show a positive correlation between Γ and ṁEdd. This transition from harder-when-brighter at low ṁEdd~to softer-when-brighter at high ṁEdd~can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonising corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that LINERs are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion-rate end of the hard state or in the hard-intermediate state.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  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. [O iii] λ5007 and X-Ray Properties of a Complete Sample of Hard X-Ray Selected AGNs in the Local Universe

    NASA Astrophysics Data System (ADS)

    Ueda, Y.; Hashimoto, Y.; Ichikawa, K.; Ishino, Y.; Kniazev, A. Y.; Väisänen, P.; Ricci, C.; Berney, S.; Gandhi, P.; Koss, M.; Mushotzky, R.; Terashima, Y.; Trakhtenbrot, B.; Crenshaw, M.

    2015-12-01

    We study the correlation between the [O iii] λ5007 and X-ray luminosities of local active galactic nuclei (AGNs), using a complete, hard X-ray (>10 keV) selected sample in the Swift/BAT 9-month catalog. From our optical spectroscopic observations at the South African Astronomical Observatory and the literature, a catalog of [O iii] λ5007 line flux for all 103 AGNs at Galactic latitudes of | b| \\gt 15^\\circ is compiled. Significant correlations with intrinsic X-ray luminosity ({L}{{X}}) are found for both observed ({L}[{{O} {{III}}] }) and extinction-corrected ({L}[{{O} {{III}}]}{{cor}}) luminosities, separately for X-ray unabsorbed and absorbed AGNs. We obtain the regression form of {L}[{{O} {{III}}] } \\propto \\{L}2-10\\{keV}1.18+/- 0.07 and {L}[{{O} {{III}}]}{{cor}} \\propto \\{L}2-10\\{keV}1.16+/- 0.09 from the whole sample. The absorbed AGNs with low (<0.5%) scattering fractions in soft X-rays show on average smaller {L}[{{O} {{III}}]}/{L}{{X}} and {L}[{{O} {{III}}]}{{cor}}/{L}{{X}} ratios than the other absorbed AGNs, while those in edge-on host galaxies do not. These results suggest that a significant fraction of this population is buried in tori with small opening angles. By using these {L}[{{O} {{III}}] } versus {L}{{X}} correlations, the X-ray luminosity function (LF) of local AGNs (including Compton-thick AGNs) in a standard population synthesis model gives much better agreement with the [O iii] λ5007 LF derived from the Sloan Digital Sky Survey than previously reported. This confirms that hard X-ray observations are a very powerful tool to find AGNs with high completeness.

  6. The Far-IR View of an Ultra-Hard X-ray Selected Sample of AGN

    NASA Astrophysics Data System (ADS)

    Shimizu, Thomas; Melendez, M.; Mushotzky, R.; Barger, A. J.; Cowie, L. L.

    2014-01-01

    We present early results of the Herschel PACS (70 and 160 μm) and SPIRE (250, 350, and 500 μm) survey of 313 low redshift (z < 0.05), ultra-hard X-ray (14-195 keV) selected AGN from the 58 month Swift/BAT catalog. Selection of AGN from ultra-hard X-rays avoids bias from obscuration that are unavoidable at other wavelengths (eg optical, infrared, and radio) providing the most complete sample of AGN to study the connection between nuclear activity and star formation in host galaxies. With the high angular resolution of PACS, we find that ~35% and ~20% of the sources are 'point-like' at 70 and 160 μm respectively with another 20% that have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFR) of 0.1 - 100 Msun yr-1 using the 70 and 160 μm flux densities and the calibration of Calzettti et al (2010) are consistent with those inferred from Spitzer NeII fluxes, but we find that 11.25 μm PAH data give ~3x lower SFR. Using GALFIT to measure the size of the FIR emitting regions, we determined the SFR density [Msun yr-1 kpc-2] for our sample, finding a significant fraction to exist above the threshold for star formation driven winds (0.1 Msun yr-1 kpc-2, Heckman 2001). Analysis of the SPIRE colors (250/350 and 350/500) also reveals evidence for the presence of nonthermal synchrotron emission from a radio jet significantly affecting the FIR emission at long wavelengths and altering the shape of the spectral energy distribution (SED). We also will present the broad band Herschel 70-500m SEDS for our sample and include archival Spitzer, WISE, FIRST and NVSS data to extend the SED down to near-IR and up to radio wavelengths. The SEDs will be fit using multiple models to attempt to determine the AGN contribution to the FIR (indirect or direct) and ultimately its effect on nuclear star formation.

  7. A study of a sample of high rotation-measure AGNs through multifrequency single-dish observations

    NASA Astrophysics Data System (ADS)

    Pasetto, Alice; Kraus, Alex; Mack, Karl-Heinz; Bruni, Gabriele; Carrasco-González, Carlos

    2016-02-01

    Context. We characterised and studied, in the radio band, a sample of candidates for high rotation measure (RM). These point-like objects show a strong depolarisation at 21 cm. This feature suggests the presence of a very dense medium surrounding them combined with a strong magnetic field. Aims: This work aims at selecting and studying a sample of radio sources with high RM, thus studying their physical conditions and their status with respect to their surrounding medium. We want to understand whether any connection is present between the AGN-hosting galaxy medium with some evolutionary track and/or some restarting phase of the AGN itself. Methods: Multifrequency single-dish observations were performed with the 100-m Effelsberg telescope to define the initial sample, to characterise the spectral energy distribution (SED) of the final sample (30 targets), and to determine their RM in the 11 to 2 cm wavelength range. Results: From the observations, the SED and the polarisation information, i.e. the fractional polarisation and the polarisation angle, have been determined. Three different object types were revealed from the SED analysis: older, GPS-like, and mixed. For each of the targets, the rotation measure was found and the depolarisation modelled. No significant correlation is found between the depolarisation behaviours and the SEDs, while a correlation is found between sources with mixed SED (with an old component at low frequency and compact components at high frequencies) and high values of the rotation measure (with values in the rest frame greater than 1000 rad/m2). Conclusions: This work helps us to define and identify a sample of sources with high RM. From the analysis we can conclude that the sources showing a restarting phase at high frequency (with a mixed SED) are characterised by a really dense and/or a magnetised medium that strongly rotates the polarisation angle at the different frequencies, leading to a high RM.

  8. 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.

  9. 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.

  10. THE GALACTIC SPIN OF AGN GALAXIES

    SciTech Connect

    Cervantes-Sodi, Bernardo; Hernandez, X.; Park, Changbom; Choi, Yun-Young E-mail: xavier@astroscu.unam.mx

    2011-07-01

    Using an extensive sample of galaxies selected from the Sloan Digital Sky Survey Data Release 5, we compare the angular momentum distribution of active galactic nuclei (AGNs) with non-AGN hosting late-type galaxies. To this end we characterize galactic spin through the dimensionless angular momentum parameter {lambda}, which we estimate through simple dynamical considerations. Using a volume-limited sample, we find a considerable difference when comparing the empirical distributions of {lambda} for AGNs and non-AGN galaxies, the AGNs showing typically low {lambda} values and associated dispersions, while non-AGNs present higher {lambda} values and a broader distribution. A more striking difference is found when looking at {lambda} distributions in thin M{sub r} cuts; while the spin of non-AGN galaxies presents an anticorrelation with M{sub r} , with bright (massive) galaxies having low spins, AGN host galaxies present uniform values of {lambda} at all magnitudes, a behavior probably imposed by the fact that most late-type AGN galaxies present a narrow range in color, with a typical constant {lambda} value. We also find that the fraction of AGN hosting galaxies in our sample strongly depends on galactic spin, increasing dramatically for decreasing {lambda}. For AGN host galaxies, we compute the mass of their supermassive black holes and find that this value tends to be higher for low spin galaxies, even at fixed luminosity, a result that could account, to a certain extent, for the spread on the luminosity-black-hole mass relation.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2013-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  14. 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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  17. Decreased specific star formation rates in AGN host galaxies

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  18. Radio Loud AGNs are Mergers

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  19. X-ray selected AGN in a Merging Cluster Environment

    NASA Astrophysics Data System (ADS)

    Norman, Dara; Coldwell, Georgina; Soechting, Ilona

    2010-08-01

    Although a general understanding of the overall AGN population is being addressed by optical large area surveys, a complete picture of cluster AGN is hampered by survey biases and a lack of information about AGN environments where we can trace cluster interactions. Optically selected AGN are under-represented in cluster environments due to color selection criteria insensitive to red and dusty sources. X-ray selection of AGN can overcome this bias. Hierarchical simulations suggest the gravitational processes which govern the evolution of clusters also have a role in AGN triggering, and AGN feedback is critically important to galaxy evolution. Confirmation of models requires comparisons not just of the cluster galaxy population, but also of the distributions of AGN in clusters especially forming clusters, which are not fully identified in surveys. Weak lensing cluster selection can overcome this bias. We propose to obtain GMOS-S spectra for a sample of 23 X-ray selected , optically faint (20 with R>20.3) AGN cluster candidates in an X-ray cluster discovered by its weak lensing shear signal. This cluster is unique in the large number of 1) X-ray AGN candidates identified in its environment and 2) X-ray sub-clusters identified. We require redshift data to identify AGN cluster members.

  20. Compton Thick AGN in the COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, Giorgio; Cosmos Collaboration

    2015-09-01

    I will present the results we published in a couple of recent papers (Lanzuisi et al. 2015, A&A 573A 137, Lanzuisi et al. 2015, arXiv 1505.01153) on the properties of X-ray selected Compton Thick (CT, NH>10^24 cm^-2) AGN, in the COSMOS survey. We exploited the rich multi-wavelength dataset available in this field, to show that CT AGN tend to harbor smaller, rapidly growing SMBH with respect to unobscured AGN, and have a higher chance of being hosted by star-forming, merging and post-merger systems.We also demonstrated the detectability of even more heavily obscured AGN (NH>10^25 cm^-2), thanks to a truly multi-wavelength approach in the same field. The extreme source detected in this way shows strong evidences of ongoing powerful AGN feedback, detected as blue-shifted wings of high ionization optical emission lines such as [NeV] and [FeVII], as well as of the [OIII] emission line.The results obtained from these works point toward a scenario in which highly obscured AGN occupy a peculiar place in the galaxy-AGN co-evolution process, in which both the host and the SMBH rapidly evolve toward the local relations.We will also present estimates on the detectability of such extreme sources up to redshift ~6-7 with Athena. Combining the most up to date models for the Luminosity Function of CT AGN at high z, aggressive data analysis techniques on faint sources, and the current Athena survey design, we demonstrate that we will detect, and recognize as such, a small (few to ten) but incredibly valuable sample of CT AGN at such high redshift.

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

    SciTech Connect

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

    2009-05-20

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

  2. 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.

  3. Low luminosity AGNs in the local universe

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  4. 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.

  5. Spectral Energy Distributions of Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Hao, Heng

    The spectral energy distributions (SEDs) of active galactic nuclei (AGNs) are essential to understand the physics of supermassive black holes (SMBHs) and their host galaxies. This thesis present a detailed study of AGN SED shapes in the optical-near infrared bands (0.3--3microm) for 413 X-ray selected Type 1 AGNs from the XMM-COSMOS Survey. We define a useful near-IR/optical index-index ('color-color') diagram to investigate the mixture of AGN continuum, host galaxy and reddening contributions. We found that ˜90% of the AGNs lie on mixing curves between the Elvis et al. (1994) mean AGN SED (E94) and a host galaxy, with only the modest reddening [E(B-V)=0.1--0.2] expected in type 1 AGNs. Lower luminosity and Eddington ratio objects have more host galaxy, as expected. The E94 template is remarkably good in describing the SED shape in the 0.3--3microrn decade of the spectrum over a range of 3.2 dex in LOPT, 2.7 dex in L/LEdd, and for redshifts up to 3. The AGN phenomenon is thus insensitive to absolute or relative accretion rate and to cosmic time. However, 10% of the AGNs are inconsistent with any AGN+host+reddening mix. These AGNs have weak or non-existent near-IR bumps, suggesting a lack of the hot dust characteristic of AGNs. The fraction of these hot-dust-poor AGNs evolves with redshift from 6% at low redshift (z < 2) to 20% at moderately high redshift (2 < z < 3.5). A similar fraction of HDP quasars are found in the Elvis et al. 1994 (BQS) and Richards et al. 2006 (SDSS) samples. The 1--3microm emission of the HDP quasars is a factor 2--4 smaller than the typical E94 AGN SED. The implied torus covering factor is 2%--29%, well below the 75% required by unified models. The weak hot dust emission seems to expose an extension of the accretion disk continuum in some of AGNs. For these, we estimate the outer edge of their accretion disks to lie at ˜104 Schwarzschild radii, more than ten times the gravitational stability radii. Either the host-dust is destroyed

  6. 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.

  7. 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

  8. 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.

  9. Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria

    NASA Astrophysics Data System (ADS)

    Donley, Jennifer; Koekemoer, A. M.; Brusa, M.; Capak, P.; Cardamone, C. N.; Civano, F.; Ilbert, O.; Impey, C. D.; Kartaltepe, J.; Miyaji, T.; Salvato, M.; Sanders, D. B.; Trump, J. R.; Zamorani, G.

    2012-01-01

    Spitzer IRAC selection is a powerful tool for identifying luminous AGN. The AGN selection wedges currently in use, however, are heavily contaminated by star-forming galaxies, especially at high redshift. Using the large samples of luminous AGN and high-redshift star-forming galaxies in COSMOS, we redefine the AGN selection criteria for use in deep IRAC surveys. The new IRAC criteria are designed to be both highly complete and reliable, and incorporate the best aspects of the current AGN selection wedges and of infrared power-law selection while excluding high redshift star-forming galaxies selected via the BzK, DRG, LBG, and SMG criteria. At QSO-luminosities of log L(2-10 keV)>44, the new IRAC criteria recover 75% of the hard X-ray and IRAC-detected XMM-COSMOS sample, yet only 37% of the IRAC AGN candidates have X-ray counterparts, a fraction that rises to 51% in regions with Chandra exposures of 50-160 ks. X-ray stacking of the individually X-ray non-detected AGN candidates leads to a hard X-ray signal indicative of heavily obscured to mildly Compton-thick obscuration (log NH >= 23.7). While IRAC selection recovers a substantial fraction of luminous unobscured and obscured AGN, it is incomplete to low-luminosity and host-dominated AGN.

  10. Are the hosts of VLBI-selected radio-AGN different to those of radio-loud AGN?

    NASA Astrophysics Data System (ADS)

    Rees, G. A.; Norris, R. P.; Spitler, L. R.; Herrera-Ruiz, N.; Middelberg, E.

    2016-05-01

    Recent studies have found that radio-AGN selected by radio-loudness show little difference in terms of their host galaxy properties when compared to non-AGN galaxies of similar stellar mass and redshift. Using new 1.4 GHz very long baseline interferometry (VLBI) observations of the Cosmological Evolution Survey field, we find that approximately 49 ± 8 per cent of high-mass (M > 1010.5 M⊙), high-luminosity (L1.4 > 1024 W Hz-1) radio-AGN possess a VLBI-detected counterpart. These objects show no discernible bias towards specific stellar masses, redshifts or host properties other than what is shown by the radio-AGN population in general. Radio-AGN that are detected in VLBI observations are not special, but form a representative sample of the radio-loud AGN population.

  11. Anchoring the AGN X-ray Luminosity Function

    NASA Astrophysics Data System (ADS)

    Salzer, John

    2003-09-01

    Knowledge of the AGN LF over a range of luminosities and redshifts is crucial to understanding the accretion history of supermassive blackholes. Much of the CXRB has been resolved and spectroscopic follow-up has revealed a mixed bag of object types at moderate to high redshifts. For the deep Chandra survey results to be useful in studying the evolution of the XLF, a representative sample of local AGNs of various types with known X-ray luminosities is needed. The new KPNO International Spectroscopic Survey (KISS) provides the best available sample of H-alpha selected Type 1 and 2 AGNs to serve as the baseline for XLF evolution studies. We propose to observe a volume-limited sample of 28 KISS AGNs to assess their X-ray emission characteristics and establish the local AGN XLF.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  13. Propiedades de los AGNs oscurecidos y no oscurecidos

    NASA Astrophysics Data System (ADS)

    Taormina, M.; Bornancini, C.

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

  14. Long Timescale Variability of AGN with RXTE

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.; Uttley, P.; Taylor, R. D.; Seymour, N.

    2004-07-01

    In this paper we review the very large contribution made by RXTE to our understanding of Active Galaxies (AGN). We discuss the relationship between AGN and Galactic Black Hole X-ray binary systems (GBHs) and show, by comparison of their powerspectral densities (PSDs) that some AGN are the equivalent of GBHs in their `high' state, rather than in their `low' state as has previously been assumed. We plot the timescale at which the PSD slope steepens from -1 to -2 against the black hole mass for a sample of AGN, and for Cyg X-1 in its high and low states. We find it is not possible to fit all AGN to the same linear scaling of break timescale with black hole mass. However broad line AGN are consistent with a linear scaling of break timescale with mass from Cyg X-1 in its low state and NLS1 galaxies scale better with Cyg X-1 in its high state, although there is an exception, NGC3227. We suggest that the relationship between black hole mass and break timescale is a function of another underlying parameter which may be accretion rate or black hole spin or, probably, both. We examine X-ray spectral variability and show how simple `flux-flux' plots can distinguish between `two-component' and `spectral pivoting' models. We also examine the relationship between the X-ray emission and that in other wavebands. In the case of X-ray/optical variability we show how cooler discs in AGN with larger mass black holes lead to greater proximity of the X-ray and optical emission regions and hence to more highly correlated variability. The very large amplitude of optical variability then rules out reprocessing as the origin of the optical emission. We show how the radio emission in NGC 4051 is strongly correlated with the X-ray emission, implying some contribution to the X-ray emission from a jet for which there is some evidence in radio images. We point out, however, that we have only studied in detail the X-ray variability of a handful of AGN. There is a strong requirement to extend such

  15. 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.

  16. Uncovering AGN Fueling and Feedback in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Mushotzky, Richard

    2014-09-01

    While massive black holes (BHs) are ubiquitous in massive galaxies, their presence in dwarf galaxies is less certain. This constitutes a major gap in our understanding of BH-galaxy co-evolution. Identifying low-mass BHs in local dwarfs could also constrain BH seed formation at high z. Active BHs in dwarfs can reveal BH fueling and feedback in a vastly different regime than the well-studied AGN in massive hosts. Most AGN feedback models focus on the latter, as star formation is thought to suffice to drive feedback in dwarfs. However, AGN are increasingly found in dwarfs, where their effect on hosts may be most dramatic. We propose an unprecedented program to detect and characterize AGN fueling and feedback in the low-mass regime, using a unique sample of Swift-BAT AGN in dwarf

  17. 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.

  18. The Starburst-AGN Connection under the Multiwavelength Limelight

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2011-11-01

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

  19. 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}.

  20. SWIFT Observations AGN

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard

    2008-01-01

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

  1. The PEP survey: infrared properties of radio-selected AGN

    NASA Astrophysics Data System (ADS)

    Magliocchetti, M.; Lutz, D.; Rosario, D.; Berta, S.; Le Floc'h, E.; Magnelli, B.; Pozzi, F.; Riguccini, L.; Santini, P.

    2014-07-01

    By exploiting the VLA-COSMOS and the Herschel-PEP surveys, we investigate the far-infrared (FIR) properties of radio-selected AGN. To this purpose, from VLA-COSMOS we considered the 1537, F1.4 GHz ≥ 0.06 mJy sources with a reliable redshift estimate, and sub-divided them into star-forming galaxies and AGN solely on the basis of their radio luminosity. The AGN sample is complete with respect to radio selection at all z ≲ 3.5. 832 radio sources have a counterpart in the PACS Evolutionary Probe catalogue. 175 are AGN. Their redshift distribution closely resembles that of the total radio-selected AGN population, and exhibits two marked peaks at z ˜ 0.9 and 2.5. We find that the probability for a radio-selected AGN to be detected at FIR wavelengths is both a function of radio power and redshift, whereby powerful sources are more likely to be FIR emitters at earlier epochs. This is due to two distinct effects: (1) at all radio luminosities, FIR activity monotonically increases with look-back time and (2) radio activity of AGN origin is increasingly less effective at inhibiting FIR emission. Radio-selected AGN with FIR emission are preferentially located in galaxies which are smaller than those hosting FIR-inactive sources. Furthermore, at all z ≲ 2, there seems to be a preferential (stellar) mass scale M* ˜ [1010-1011] M⊙ which maximizes the chances for FIR emission. We find such FIR (and mid-infrared) emission to be due to processes indistinguishable from those which power star-forming galaxies. It follows that radio emission in at least 35 per cent of the entire AGN population is the sum of two contributions: AGN accretion and star-forming processes within the host galaxy.

  2. 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°.

  3. Star Formation Quenching and Identifying AGN in Galaxies

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  4. Cadence Requirements for AGN Accretion Studies with LSST

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We test various samplings of mock AGN lightcurves to determine minimum cadence requirements for future technologies like the Large Synoptic Survey Telescope (LSST). AGN lightcurves exhibit stochastic behavior, with variability seen in ground-based optical surveys on timescales from days to years. Significant variability structure on timescales up to a few days was revealed by the high time resolution (~30 minutes) of Kepler Satellite. Now it is apparent that under-sampling by ground based instruments may be leaving out a big chunk of the AGN accretion picture. To probe Kepler AGN, recent studies have investigated the suitability of sophisticated models like CARMA processes to better understand dominant mechanisms driving observed variability across these timescales. By testing models against AGN photometry, we gain insights about accretion physics, intrinsic differences between AGN sub-types, and physical scales pertaining to orbits or casually connected matter flows. We investigate cadence, time window, and regularity requirements that accurately recover parameters of our model lightcurves constructed with a CARMA process and observations such that ground based telescopes can optimally collect data for AGN science.

  5. 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.

  6. PRIMUS: Infrared and X-Ray AGN Selection Techniques at 0.2 < z < 1.2

    NASA Astrophysics Data System (ADS)

    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

    2013-06-01

    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 deg2. 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 ~75% of IR-selected AGNs are also identified as X-ray AGNs. This fraction increases to ~90% when comparing against the deepest X-ray data, indicating that at most ~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.

  7. Ionized Absorbers in AGN

    NASA Astrophysics Data System (ADS)

    Mathur, S.

    1999-08-01

    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".

  8. 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".

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Sun, Ai-Lei

    2016-01-01

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

  12. 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.

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

    SciTech Connect

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

    2012-10-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

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

    SciTech Connect

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

    2010-07-15

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

  16. Galaxy Zoo: AGN may be fueled by stellar bars in the local Universe

    NASA Astrophysics Data System (ADS)

    Galloway, Melanie; Willett, Kyle; Fortson, Lucy; Galaxy Zoo Science Team

    2015-01-01

    Bars are a mechanism that have been proposed to explain how gas in the outer regions of a galaxy can be channeled inward and fuel AGN. Multiple observational studies have reported a significantly higher bar fraction in AGN than non-AGN. To accurately probe whether an excess of bars in AGN host galaxies exists because the galaxies host a bar, it is necessary to compare bar and AGN fractions at fixed mass and color, because the presence of bars strongly correlates with both. Thus, a sufficiently large sample is necessary to maintain adequate numbers in subsets of fixed mass and color. We have created a large, volume-limited sample of 19,765 disc galaxies using data from the Sloan Digital Sky Survey. By using morphological classifications from the Galaxy Zoo 2 project, we identify stellar bars in 51.8% of AGN hosts and 37.1% of star-forming disk galaxies. Once mass and color are fixed, there remains a statistically significant increase in the fraction of barred AGN over their unbarred counterparts. Using the L[O III]/MBH ratio as a measure of accretion efficiency, we also show that barred AGN do not exhibit stronger accretion than unbarred AGN at fixed mass or color. The data are consistent with a model in which bar-driven fueling does contribute to the probability of an actively growing black hole, but in which other dynamical mechanisms must contribute to AGN fueling via smaller, non-axisymmetric perturbations.

  17. The bulge-disc decomposition of AGN host galaxies

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  18. Models of AGN feedback

    NASA Astrophysics Data System (ADS)

    Combes, Françcoise

    2015-02-01

    The physical processes responsible of sweeping up the surrounding gas in the host galaxy of an AGN, and able in some circumstances to expel it from the galaxy, are not yet well known. The various mechanisms are briefly reviewed: quasar or radio modes, either momentum-conserving outflows, energy-conserving outflows, or intermediate. They are confronted to observations, to know whether they can explain the M-sigma relation, quench the star formation or whether they can also provide some positive feedback and how the black hole accretion history is related to that of star formation.

  19. Completing the AGN Census for Nearby Galaxies (Archival Component)

    NASA Astrophysics Data System (ADS)

    Ho, Luis

    2010-09-01

    The census of AGNs in the local Universe provides an efficient and effective estimate of the occupation fraction of central black holes in galaxies. While the demographics of AGNs in bulge-dominated systems is fairly well known, the situation in later-type galaxies is still murky because of potential optical selection biases. Searching for X-ray cores using Chandra can bypass these complications. We propose to complete the local AGN census by surveying all 188 star-forming (H II) nuclei in the well-studied Palomar sample of nearby galaxies. We request funding to analyze the 85 objects already in the archive; new observations have been proposed for the rest. We will establish with unprecedented reliability the AGN fraction across a wide range in Hubble type and Eddington ratios.

  20. 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.

  1. PRIMUS + DEEP2: Clustering of X-Ray, Radio, and IR-AGNs at z~0.7

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    We measure the clustering of X-ray, radio, and mid-IR-selected active galactic nuclei (AGNs) at 0.2\\lt z\\lt 1.2 using multi-wavelength imaging and spectroscopic redshifts from the PRIMUS and DEEP2 redshift surveys, covering seven separate fields spanning ∼10 deg 2 . Using the cross-correlation of AGNs with dense galaxy samples, we measure the clustering scale length and slope, as well as the bias, of AGNs selected at different wavelengths. Similar to previous studies, we find that X-ray and radio AGNs are more clustered than mid-IR-selected AGNs. We further compare the clustering of each AGN sample with matched galaxy samples designed to have the same stellar mass, star-formation rate (SFR), and redshift distributions as the AGN host galaxies and find no significant differences between their clustering properties. The observed differences in the clustering of AGNs selected at different wavelengths can therefore be explained by the clustering differences of their host populations, which have different distributions in both stellar mass and SFR. Selection biases inherent in AGN selection therefore determine the clustering of observed AGN samples. We further find no significant difference between the clustering of obscured and unobscured AGNs, using IRAC or Wide-field Infrared Survey Explorer colors or X-ray hardness ratio.

  2. 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.

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

    DOE PAGESBeta

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

    2015-06-19

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

  4. The softest Einstein AGN (active galactic nuclei)

    SciTech Connect

    Cordova, F.A.; Kartje, J.; Mason, K.O.; Mittaz, J.P.D.; Chicago Univ., IL; University Coll., London . Mullard Space Science Lab.)

    1989-01-01

    We have undertaken a coarse spectral study to find the softest sources detected with the Imaging Proportional Counter (IPC) on the Einstein Observatory. Of the nearly 7700 IPC sources, 226 have color ratios that make them candidate ultrasoft'' sources; of these, 83 have small enough errors that we can say with confidence that they have a spectral component similar to those of the white dwarfs Sirius and HZ 43, nearby stars such as {alpha} Cen and Procyon, and typical polar'' cataclysmic variables. By means of catalog searches and ground-based optical and radio observations we have thus far identified 96 of the 226 candidate soft sources; 37 of them are active galactic nuclei (AGN). In the more selective subset of 83 sources, 47 have been identified, 12 of them with AGN. The list of 47 identifications is given in Cordova et al. For one QSO in our sample, E0132.8--411, we are able to fit the pulse-height data to a power-law model and obtain a best fit for the energy spectral index of 2. 2{sub {minus}0.4}{sup +0.6}. For the remainder of the AGN in the higher confidence sample we are able to infer on the basis of their x-ray colors that they have a similar spectral component. Two-thirds of the AGN are detected below 0.5 keV only, while the remainder evidence a flatter spectral component in addition to the ultra-soft component. 14 refs., 5 figs.

  5. 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.

  6. Clustering of ROSAT All-Sky Survey AGNs Through Cross-Correlation Functions

    NASA Astrophysics Data System (ADS)

    Krumpe, Mirko; Miyaji, Takamitsu; Coil, Alison

    2010-07-01

    We investigate the clustering propertiesof ~1550 low-redshift broad-line AGNs detected in the ROSAT All-Sky Survey (RASS) through a cross-correlation function (CCF) with ~46000 Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS). Using this approach, we avoid small-number statistics and systematic errors caused by the variation of the Galactic absorption compared to a direct measurement of the AGN auto-correlation function (ACF). We compute the ACF of low-z RASS-AGN based on the CCF for the total X-ray sample ( = 0.25) and found a correlation length of r0 = 4.3-0.4+0.4 h-1 Mpc. Furthermore, we discovered an X-ray luminosity dependence of the clustering signal, i.e. high luminosity AGN cluster stronger than low luminosity AGN. We have also applied a Halo Occupation Distribution (HOD) model directly to our AGN-LRG CCF.

  7. 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.

  8. 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.

  9. AGN Science: The Past, The Present, The Future . AGN Science

    NASA Astrophysics Data System (ADS)

    Boller, Th.

    I review some basic results on AGN science by concentrating on the Fe K and Fe L line observations and on the Narrow-Line Seyfert 1 physics. This paper is based on a talk given at the Vulcano workshop, 'The multifrequency behavior of high energy cosmic sources` in 2009. Given the length of the talk and the number of pages the review on AGN science cannot be complete and is biased towards two science topics and my personal view.

  10. 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.

  11. Detecting AGNs using multi-filter imaging data

    NASA Astrophysics Data System (ADS)

    Dong, Xiaoyi

    2012-05-01

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

  12. AGN and their host galaxies

    NASA Astrophysics Data System (ADS)

    Steinborn, L. K.; Dolag, K.; Hirschmann, M.; Remus, R.-S.; Teklu, A. F.

    2016-06-01

    Large scale cosmological hydrodynamic simulations are an important tool to study the co-evolution between black holes (BHs) and their host galaxies. However, in order to model the accretion onto BHs and AGN feedback we need sub-grid models which contain several free parameters. The choice of these parameters has a significant impact on the properties of the BHs and their host galaxies. Therefore, we improve the accretion model and the AGN feedback model based on both theory and observations to eliminate most free parameters. In that way, the slope of the observed relation between BH mass and stellar mass is reproduced self-consistently. We performed a few extremely large simulation runs as part of the Magneticum Pathfinder simulation set, combining a high resolution with very large cosmological volumes, enabling us to study for example dual AGN, the role of galaxy mergers and AGN clustering properties.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  14. 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.

  15. Are Compton-thick AGNs the Missing Link between Mergers and Black Hole Growth?

    NASA Astrophysics Data System (ADS)

    Kocevski, Dale D.; Brightman, Murray; Nandra, Kirpal; Koekemoer, Anton M.; Salvato, Mara; Aird, James; Bell, Eric F.; Hsu, Li-Ting; Kartaltepe, Jeyhan S.; Koo, David C.; Lotz, Jennifer M.; McIntosh, Daniel H.; Mozena, Mark; Rosario, David; Trump, Jonathan R.

    2015-12-01

    We examine the host morphologies of heavily obscured active galactic nuclei (AGNs) at z∼ 1 to test whether obscured super-massive black hole growth at this epoch is preferentially linked to galaxy mergers. Our sample consists of 154 obscured AGNs with {N}{{H}}\\gt {10}23.5 {{cm}}-2 and z\\lt 1.5. Using visual classifications, we compare the morphologies of these AGNs to control samples of moderately obscured (1022 cm{}-2\\lt {N}{{H}}\\lt {10}23.5 {{cm}}-2) and unobscured ({N}{{H}}\\lt {10}22 {{cm}}-2) AGN. These control AGNs have similar redshifts and intrinsic X-ray luminosities to our heavily obscured AGN. We find that heavily obscured AGNs are twice as likely to be hosted by late-type galaxies relative to unobscured AGNs ({65.3}-4.6+4.1% versus {34.5}-2.7+2.9%) and three times as likely to exhibit merger or interaction signatures ({21.5}-3.3+4.2% versus {7.8}-1.3+1.9%). The increased merger fraction is significant at the 3.8σ level. If we exclude all point sources and consider only extended hosts, we find that the correlation between the merger fraction and obscuration is still evident, although at a reduced statistical significance (2.5σ ). The fact that we observe a different disk/spheroid fraction versus obscuration indicates that the viewing angle cannot be the only thing differentiating our three AGN samples, as a simple unification model would suggest. The increased fraction of disturbed morphologies with obscuration supports an evolutionary scenario, in which Compton-thick AGNs are a distinct phase of obscured super-massive black hole (SMBH) growth following a merger/interaction event. Our findings also suggest that some of the merger-triggered SMBH growth predicted by recent AGN fueling models may be hidden among the heavily obscured, Compton-thick population.

  16. 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.

  17. Calibrating AGN Feedback in Clusters

    NASA Astrophysics Data System (ADS)

    Wise, M. W.

    2009-12-01

    Whether caused by AGN jets, shocks, or mergers, the most definitive evidence for heating in cluster cores comes from X-ray spectroscopy. Unfortunately such spectra are essentially limited to studying the emission spectrum from the cluster as a whole. However since the same underlying emission measure distribution produces both the observed CCD and RGS spectra, X-ray imaging can still provide spatial information on the heating process. Using Chandra archival data for a sample of 9 clusters, we demonstrate how imaging data can be used to constrain departures from a canonical, isobaric cooling flow model as a function of position in a given cluster. The results of this analysis are also shown for the deep archival exposure of the Perseus cluster. Such ``heating maps'' can provide constraints on both the location and magnitude of the heating in the cores of clusters. When combined with detections and spectral index maps from low-frequency radio observations, these maps can be used to distinguish between different models for heating in these objects.

  18. Cold-gas outflows in typical low-redshift galaxies are driven by star formation, not AGN

    NASA Astrophysics Data System (ADS)

    Sarzi, Marc; Kaviraj, Sugata; Nedelchev, Borislav; Tiffany, Joshua; Shabala, Stanislav S.; Deller, Adam T.; Middelberg, Enno

    2016-02-01

    Energetic feedback from active galactic nuclei (AGN) is an important ingredient for regulating the star formation history of galaxies in models of galaxy formation, which makes it important to study how AGN feedback actually occurs in practice. In order to catch AGNs in the act of quenching star formation, we have used the interstellar Na I λλ5890, 5895(NaD) absorption lines to look for cold-gas outflows in a sample of 456 nearby galaxies for which we could unambiguously ascertain the presence of radio-AGN activity, thanks to radio imaging at milli-arcsecond scales. While compact radio emission indicating a radio AGN was found in 103 galaxies (23 per cent of the sample), and 23 objects (5 per cent) exhibited NaD absorption-line kinematics suggestive of cold-gas outflows, not one object showed evidence of a radio AGN and of a cold-gas outflow simultaneously. Radio-AGN activity was found predominantly in early-type galaxies, while cold-gas outflows were mainly seen in spiral galaxies with central star formation or composite star formation/AGN activity. Optical AGNs also do not seem capable of driving galactic winds in our sample. Our work adds to a picture of the low-redshift Universe, where cold-gas outflows in massive galaxies are generally driven by star formation and where radio-AGN activity occurs most often in systems in which the gas reservoir has already been significantly depleted.

  19. Photometric and Astrometric Characterization of the La Silla QUEST AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Coppi, Paolo S.; Cartier, R. A.; QUEST Team

    2014-01-01

    We study the photometric and astrometric properties of the La Silla QUEST AGN Variability Survey and present preliminary results. This wide-field survey is designed to collect well-sampled AGN light curves, on day to year timescales, in order to better characterize the variability properties of a large sample of AGN selected by a variety of other techniques. These properties can then be used to test and improve AGN variability selection techniques, e.g., to better prepare for the arrival of LSST. Additionally, we hope to connect these variability properties to the fundamental physical parameters of AGN such as black hole mass. To achieve this goal, we carry out nightly observations of a set of extragalactic fields with good multiwavelength coverage such as COSMOS. The survey uses the QUEST camera (with ~7.5 square degree field-of-view) operating on the 1m ESO Schmidt located in La Silla, Chile. The survey began in March 2010 and will likely continue for at least two more years. We review our progress and present sample AGN light curves from the first two years of the survey. We use the two-year data to test for possible biases in current selection variability techniques by looking at the known AGN in the COSMOS field. The larger QUEST variabiliity survey, which is now being used to find supernova, will eventually provide high-quality AGN variability data over ~15,000 square degrees of sky.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  2. The INTEGRAL/IBIS AGN catalogue: an update

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. The INTEGRAL/IBIS AGN catalogue: an update

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  4. VizieR Online Data Catalog: ASCA AGN optical identifications (Akiyama+, 2003)

    NASA Astrophysics Data System (ADS)

    Akiyama, M.; Ueda, Y.; Ohta, K.; Takahashi, T.; Yamada, T.

    2003-10-01

    We present the results of optical spectroscopic identifications of a bright subsample of 2-10keV hard X-ray-selected sources from the ASCA Medium Sensitivity Survey in the northern sky (AMSSn). The flux limit of the subsample is 3x10-13erg/s/cm2 in the 2-10keV band. All but one of the 87 hard X-ray-selected sources are optically identified, with AGNs (including broad-line AGNs, narrow-line AGNs, and three BL Lac objects), seven clusters of galaxies, and one galactic star. It is the largest complete sample of hard X-ray-selected AGNs at the bright flux limit. Amounts of absorption to their nuclei are estimated to be hydrogen column densities (NH) of up to 3x1023cm-2 from their X-ray spectra. Optical properties of X-ray absorbed AGNs with NH>1x1022cm-2 indicate the effects of dust absorption: at redshifts z<0.6, AGNs without broad H{beta} emission lines have significantly larger NH-values than AGNs with broad H{beta} emission lines. At z>0.6, the X-ray absorbed AGNs have a large hard X-ray to optical flux ratio (logf2-10keV/fR>+1). However, three X-ray absorbed z>0.6 AGNs show strong broad lines. In combination with hard X-ray-selected AGN samples from the ASCA Large Sky Survey, the ASCA Deep Survey in the Lockman Hole, and Chandra Deep Field North, the luminosity distributions of absorbed (NH>1x1022cm-2) and less-absorbed (NH<1x1022cm-2) AGNs are compared. (4 data files).

  5. 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.

  6. THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

    SciTech Connect

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

    2012-04-10

    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{sup +4.1}{sub -2.9} Multiplication-Sign 10{sup -5} Mpc{sup -3} for objects with a de-absorbed luminosity larger than 2 Multiplication-Sign 10{sup 42} erg s{sup -1}. 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 ({<=}85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

  7. 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..

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  9. Compton thick AGN in the XMM-COSMOS survey

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  10. AGN and Star Formation in HerMES-IRS sources

    NASA Astrophysics Data System (ADS)

    Feltre, Anna; Hatziminaoglou, Evanthia; Hernán-Caballero, Antonio; Fritz, Jacopo; Franceschini, Alberto

    2014-07-01

    One of the remaining open issues in the context of the analysis of Active Galactic Nuclei (AGN) is the evidence that nuclear gravitational accretion is often accompanied by a concurrent starburst activity. We developed a spectral energy distribution (SED) fitting technique to derive simultaneously the physical properties of active galaxies and coexisting starbursts making the best use of Spitzer and Herschel IR observations. We apply the SED fitting procedure to a large sample of extragalactic sources representing the HerMES (Herschel/Multi-tiered Extragalactic Survey) population with IRS spectra with a plethora of multi-wavelength data in order to study the impact of a possible presence of an AGN on the host galaxy's properties. We analyze the star formation rate (SFR) in conncetion to the presence of an AGN and compared the properties of the hot (AGN) and cold (starburst) dust component. Our findings are consistent with no evidence for the presence of an AGN affecting the star formation processes of the host galaxies.

  11. The QUEST-La Silla AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Cartier, R.; Lira, P.; Coppi, P.; Sánchez, P.; Arévalo, P.; Bauer, F. E.; Muñoz, R. R.

    2016-03-01

    It is widely believed that supermassive black holes reside at the centres of every massive galaxy. When actively accreting they are known as Active Galactic Nuclei (AGNs). Most commonly, their presence is exposed by the radiation generated by the accretion of matter toward their centres. This radiation can show dramatic flux variations on timescales from minutes to years that can be observed across the full electromagnetic spectrum from X-ray to radio wavelengths. Although the exact origin of AGN variability remains unclear, such variability can be used as an efficient tool to find them and to understand the origin and demographics of flux variations. To this end, we have undertaken an AGN variability survey using the QUEST camera on the ESO 1.0-metre Schmidt Telescope at La Silla. The QUEST-La Silla AGN Variability Survey aims to discover thousands of new AGNs, and provide highly sampled light curves to study the ultraviolet/optical flux variations to a limiting magnitude of r ~ 21.5 mag.

  12. Optical variability of the Kepler AGN

    NASA Astrophysics Data System (ADS)

    Edelson, Rick

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  14. The search for red AGN with 2MASS

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. The Role of Environment in Fueling Seyfert AGN

    NASA Astrophysics Data System (ADS)

    Hicks, Erin Kathleen Strobel

    2015-08-01

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

  16. Tracing outflows in the AGN forbidden region with SINFONI

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  17. The QUEST-La Silla AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Cartier, Régis; Lira, Paulina; Coppi, Paolo; Sánchez, Paula; Arévalo, Patricia; Bauer, Franz E.; Rabinowitz, David; Zinn, Robert; Muñoz, Ricardo R.; Meza, Nicolás

    2015-09-01

    We present the characterization and initial results from the QUEST-La Silla active galactic nucleus (AGN) variability survey. This is an effort to obtain well-sampled optical light curves in extragalactic fields with unique multiwavelength observations. We present photometry obtained from 2010 to 2012 in the XMM-COSMOS field, which was observed over 150 nights using the QUEST camera on the European Southern Observatory (ESO) Schmidt telescope. The survey uses a broadband filter, the Q band, similar to the union of the g and the r filters, achieving an intrinsic photometric dispersion of 0.05 mag and a systematic error of 0.05 mag in the zero point. Since some detectors of the camera show significant nonlinearity, we use a linear correlation to fit the zero points as a function of the instrumental magnitudes, thus obtaining a good correction to the nonlinear behavior of these detectors. We obtain good photometry to an equivalent limiting magnitude of r˜ 20.5. The astrometry has an internal precision of ˜ 0\\buildrel{\\prime\\prime}\\over{.} 1 and an overall accuracy of 0\\buildrel{\\prime\\prime}\\over{.} 2 when compared to the Sloan Digital Sky Survey. Studying the optical variability of X-ray-detected sources in the XMM-COSMOS field, we find that the survey is ˜75%-80% complete to magnitudes r˜ 20, and ˜67% complete to a magnitude r˜ 21. Additionally, broad-line (BL) AGNs have larger variation amplitude than non-broad-line (NL) AGNs, with ˜80% of the BL AGNs classified as variable, while only ˜21% of the NL AGNs are classified as variable. We also find that ˜22% of objects classified as galaxies (GALs) are also variable. The determination and parameterization of the structure function ({{SF}}{norm}(τ )=A{τ }γ ) of the variable sources show that most BL AGNs are characterized by A\\gt 0.1 and γ \\gt 0.025. It is further shown that NL AGNs and GAL sources occupying the same parameter space in A and γ are very likely to correspond to obscured or low

  18. The Properties of Low-Luminosity AGN: Variability, Accretion Rate, Black Hole Mass and Color

    NASA Astrophysics Data System (ADS)

    Oleas, Juan; Podjed, Stephanie; Sarajedini, Vicki

    2016-01-01

    We present the results from a study of ~5000 Broad-Line selected AGN from the Sloan Digital Sky Survey DR7. Galaxy and AGN templates have been fit to the SDSS spectra to isolate the AGN component. The sources have absolute magnitudes in the range -23 < Mi < -18 and lie at redshifts less than z ~ 0.8. A variability analysis reveals that the anti-correlation between luminosity and variability amplitude continues to the faintest AGN in our sample (Gallastegui-Aizpun & Sarajedini 2014), though the underlying cause of the relation is still poorly understood. To address this, we further explore the connection between AGN luminosity and variability through measurement of the Hβ line width to determine black hole mass and accretion rate. We find that AGN with the highest variability amplitudes at a given luminosity appear to have lower accretion rates compared to low amplitude variables. We also investigate correlations with AGN color and accretion rate among these low-luminosity AGN.

  19. Multiwavelength AGN Surveys and Studies (IAU S304)

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.; Sanders, David B.

    2014-08-01

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

  20. The most obscured AGN in the COSMOS field

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  1. The dependency of AGN infrared colour-selection on source luminosity and obscuration. An observational perspective in CDFS and COSMOS

    NASA Astrophysics Data System (ADS)

    Messias, H.; Afonso, J. M.; Salvato, M.; Mobasher, B.; Hopkins, A. M.

    2014-02-01

    Aims: This work addresses the AGN IR-selection dependency on intrinsic source luminosity and obscuration, in order to identify and characterise biases that could affect conclusions in studies. Methods: We study IR-selected AGN in the Chandra Deep Field South (CDFS) survey and in the Cosmological Survey (COSMOS). The AGN sample is divided into low and high X-ray luminosity classes and into unobscured (type-1) and obscured (type-2) classes by means of X-ray and optical spectroscopy data. Specifically in the X-ray regime, we adopt the intrinsic luminosity taking the estimated column density (NH) into account. We also take the opportunity to highlight important differences resulting from adopting different methods of assessing AGN obscuration. Results: In agreement with previous studies, we also find that AGN IR-selection efficiency shows a decrease with decreasing source AGN X-ray luminosity. For the intermediate-luminosity AGN population (43.3 ≲ log (LX [erg s-1] ) ≲ 44), the efficiency also worsens with increasing obscuration (NH). The same sample also shows an evolution with cosmic time of the obscured fraction at the highest X-ray luminosities, independently of the adopted type-1/type-2 classification method. Conclusions: We confirm that AGN IR-selection is genuinely biased towards unobscured AGNe, but only at intermediate luminosities. At the highest luminosities, where AGN IR-selection is more efficient, there is no obscuration bias. We show that type-1 AGNe are intrinsically more luminous than type-2 AGNe only at z ≲ 1.6, thus resulting in more type-1 AGN being selected when the IR survey is shallower. Based on this and other studies, we conclude that deep hard-X-ray coverages, high-resolution IR imaging, or a combination of IR and radio data are required to recover the lower luminosity obscured AGN population. In addition, wide IR surveys are needed to recover the rare powerful, obscured AGN population. Finally, when the James Webb Space Telescope comes

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

    SciTech Connect

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

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  4. 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.

  5. Determining the radio AGN contribution to the radio-FIR correlation using the black hole fundamental plane relation

    NASA Astrophysics Data System (ADS)

    Wong, O. Ivy; Koss, M. J.; Schawinski, K.; Kapińska, A. D.; Lamperti, I.; Oh, K.; Ricci, C.; Berney, S.

    2016-04-01

    We investigate the 1.4 GHz radio properties of 92 nearby (z < 0.05) ultra hard X-ray selected Active Galactic Nuclei (AGN) from the Swift Burst Alert Telescope (BAT) sample. Through the ultra hard X-ray selection we minimise the biases against obscured or Compton-thick AGN as well as confusion with emission derived from star formation that typically affect AGN samples selected from the UV, optical and infrared wavelengths. We find that all the objects in our sample of nearby, ultra-hard X-ray selected AGN are radio quiet; 83% of the objects are classed as high-excitation galaxies (HEGs) and 17% as low-excitation galaxies (LEGs). While these low-z BAT sources follow the radio-far-infrared correlation in a similar fashion to star forming galaxies, our analysis finds that there is still significant AGN contribution in the observed radio emission from these radio quiet AGN. In fact, the majority of our BAT sample occupy the same X-ray-radio fundamental plane as have been observed in other samples, which include radio loud AGN -evidence that the observed radio emission (albeit weak) is connected to the AGN accretion mechanism, rather than star formation.

  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. The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Bassani, L.; Bazzano, A.; Bird, A. J.; Masetti, N.; Panessa, F.; Stephen, J. B.; Ubertini, P.

    2012-11-01

    In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column density. Here we mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification scheme. We find that half (48 per cent) of the sample is absorbed, while the fraction of Compton-thick AGN is small (˜7 per cent). In line with our previous analysis, we have however shown that when the bias towards heavily absorbed objects which are lost if weak and at large distance is removed, as it is possible in the local Universe, the above fractions increase to become 80 and 17 per cent. We also find that absorption is a function of source luminosity, which implies some evolution in the obscuration properties of AGN. A few peculiar classes, so far poorly studied in the hard X-ray band, have been detected and studied for the first time such as 5 X-ray bright optically normal galaxies, 5 type 2 QSOs and 11 low-ionization nuclear emission regions. In terms of optical classification, our sample contains 57 per cent of type 1 and 43 per cent of type 2 AGN; this subdivision is similar to that found in X-rays if unabsorbed versus absorbed objects are considered, suggesting that the match between optical and X-ray classifications is overall good. Only a small percentage of sources (12 per cent) does not fulfil the expectation of the unified theory as we find 22 type 1 AGN which are absorbed and 10 type 2 AGN which are unabsorbed. Studying in depth these outliers we found that most of the absorbed type 1 AGN have X-ray spectra characterized by either complex or warm/ionized absorption more likely due to ionized gas located in an accretion disc wind or in the biconical structure associated with the central nucleus, therefore

  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. Comparing Simulations of AGN Feedback

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Laor, Ari

    2012-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  16. Effectiveness of WISE colour-based selection techniques to uncover obscured AGN

    NASA Astrophysics Data System (ADS)

    Mateos, S.

    2014-07-01

    We present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects with red mid-infrared power-law spectral energy distributions. We studied the dependency of our mid-infrared selection on the AGN intrinsic luminosity and the effectiveness of our technique to uncover obscured AGN missed in X-ray surveys. To do so we used two samples of luminous AGN independently selected in hard X-ray and optical surveys. We used the largest catalogue of 887 [OIII] λ5007-selected type 2 quasars (QSO2s) at z<~0.83 in the literature from the Sloan Digital Sky Survey (SDSS), and the 258 hard (>4.5 keV) X-ray-selected AGN from the Bright Ultrahard XMM-Newton Survey (BUXS). The effectiveness of our mid-infrared selection technique increases with the AGN luminosity. At high luminosities and at least up to z~1 our technique is very effective at identifying both Compton-thin and Compton-thick AGN.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Villarroel, B.

    2015-09-01

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

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

    SciTech Connect

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

    2011-08-11

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  3. 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.

  4. AGN Winds and Blazar Phenomenology

    NASA Technical Reports Server (NTRS)

    Kazanas, Demos

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  6. The roles of star formation and AGN activity of IRS sources in the HerMES fields

    NASA Astrophysics Data System (ADS)

    Feltre, A.; Hatziminaoglou, E.; Hernán-Caballero, A.; Fritz, J.; Franceschini, A.; Bock, J.; Cooray, A.; Farrah, D.; Solares, E. A. González; Ibar, E.; Isaak, K. G.; Faro, B. Lo; Marchetti, L.; Oliver, S. J.; Page, M. J.; Rigopoulou, D.; Roseboom, I. G.; Symeonidis, M.; Vaccari, M.

    2013-09-01

    In this work, we explore the impact of the presence of an active galactic nucleus (AGN) on the mid- and far-infrared (IR) properties of galaxies as well as the effects of simultaneous AGN and starburst activity in the same galaxies. To do this, we apply a multicomponent, multiband spectral synthesis technique to a sample of 250 μm selected galaxies of the Herschel Multi-tiered Extragalactic Survey (HerMES), with Infrared Spectrograph (IRS) spectra available for all galaxies. Our results confirm that the inclusion of the IRS spectra plays a crucial role in the spectral analysis of galaxies with an AGN component improving the selection of the best-fitting hot dust (torus) model. We find a correlation between the obscured star formation rate, SFRIR, derived from the IR luminosity of the starburst component, and SFRPAH, derived from the luminosity of the PAH features, LPAH, with SFRFIR taking higher values than SFRPAH. The correlation is different for AGN- and starburst-dominated objects. The ratio of LPAH to that of the starburst component, LPAH/LSB, is almost constant for AGN-dominated objects but decreases with increasing LSB for starburst-dominated objects. SFRFIR increases with the accretion luminosity, Lacc, with the increase less prominent for the very brightest, unobscured AGN-dominated sources. We find no correlation between the masses of the hot (AGN-heated) and cold (starburst-heated) dust components. We interpret this as a non-constant fraction of gas driven by the gravitational effects to the AGN while the starburst is ongoing. We also find no evidence of the AGN affecting the temperature of the cold dust component, though this conclusion is mostly based on objects with a non-dominant AGN component. We conclude that our findings do not provide evidence that the presence of AGN affects the star formation process in the host galaxy, but rather that the two phenomena occur simultaneously over a wide range of luminosities.

  7. AGN Zoo and Classifications of Active Galaxies

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.

    2015-07-01

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

  8. 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.

  9. VizieR Online Data Catalog: AGN activity in isolated SDSS galaxies (Coziol+, 2011)

    NASA Astrophysics Data System (ADS)

    Coziol, R.; Torres-Papaqui, J. P.; Plauchu-Frayn, I.; Islas-Islas, J. M.; Ortega-Minakata, R. A.; Neri-Larios, D. M.; Andernach, H.

    2011-09-01

    We discuss the nature and origin of the nuclear activity observed in a sample of 292 SDSS narrow-emission-line galaxies, considered to have formed and evolved in isolation. All these galaxies are spiral like and show some kind of nuclear activity. The fraction of Narrow Line AGNs (NLAGNs) and Transition type Objects (TOs; a NLAGN with circumnuclear star formation) is relatively high, amounting to 64% of the galaxies. There is a definite trend for the NLAGNs to appear in early-type spirals, while the star forming galaxies and TOs are found in later-type spirals. We verify that the probability for a galaxy to show an AGN characteristic increases with the bulge mass of the galaxy (Torres-Papaqui et al. 2011), and find evidence that this trend is really a by-product of the morphology, suggesting that the AGN phenomenon is intimately connected with the formation process of the galaxies. Consistent with this interpretation, we establish a strong connection between the astration rate -- the efficiency with which the gas is transformed into stars - the AGN phenomenon, and the gravitational binding energy of the galaxies: the higher the binding energy, the higher the astration rate and the higher the probability to find an AGN. The NLAGNs in our sample are consistent with scaled-down or powered-down versions of quasars and Broad Line AGNs. (2 data files).

  10. 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.

  11. The SIX survey: evolution and properties of AGN in the local universe

    NASA Astrophysics Data System (ADS)

    Bottacini, Eugenio

    2014-07-01

    Current most sensitive surveys at soft X-ray (~ 0.5-10 keV) energies by Chandra and XMM-Newton preferably sample AGN at high-redshift (z > 0.5). At low-redshift (z < 0.5), where AGN are supposed to be in their evolution end-stage, these sources are very sparsely sampled. The low-redshift universe is best fathomed at hard X-ray energies (> 15 keV) by the INTEGRAL and the Swift missions with their coded-mask telescopes IBIS/ISGRI and BAT respectively. These instruments have two major advantages: 1) they have a huge field of view, hence allowing to sample a large number of AGN at low-redshift; 2) they operate at energies above 15 keV, hence allowing detecting photons with enough power to efficiently pierce even through the Compton-thick torus of AGN. Estimates based on observations with PDS on board the BeppoSAX satellite predict that Compton-thick AGN should dominate over unabsorbed AGN in the local universe playing an important role in reproducing the shape and intensity of the cosmic X-ray background (CXB). However coded-mask detectors suffer from heavy systematic effects preventing them from reaching their theoretical limiting sensitivity. We overcome this limit with a new and alternative approach, which has been designed ad hoc to improve the sensitivity of hard X-ray surveys by using IBIS/ISGRI and BAT. Both telescopes are so close in design that their observations can be combined to obtain a more sensitive survey. The observations are combined with resampling, merging, and cross-calibration techniques. We are able to sample limiting fluxes of the order of ~3.3 times 10-12 erg cm-2 s-1 in the 18-55 keV energy range. This is called the SIX survey, that stands for Swift-INTEGRAL X-ray survey. The SIX survey extends over a wide sky area of 6200 deg2 and it is used to obtain a persistent sample of faint AGN. The source number density (log N - log S) is a factor of 3 better than current parent surveys of BAT and IBIS/ISGRI alone. I will present a study of the

  12. Type 1 AGN at low z - III. The optical narrow-line ratios

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Laor, Ari

    2013-05-01

    We present the optical narrow-line ratios in a Sloan Digital Sky Survey (SDSS) based sample of 3175 broad Hα selected type 1 active galactic nuclei (AGN), and explore their positions in the BPT diagrams as a function of the AGN and the host properties. We find the following: (1) the luminosities of all measured narrow lines (Hα, Hβ, [O III], [N II], [S II], [O I]) show a Baldwin relation relative to the broad Hα luminosity LbHα, with slopes in the range of 0.53-0.72. (2) About 20 per cent of the type 1 AGN reside within the `Composite' and `star-forming' (SF) regions of the Baldwin, Phillips & Terlevich (BPT) diagrams. These objects also show excess narrow Hα and ultraviolet (UV) luminosities, for their LbHα, consistent with contribution from star formation which dominates the narrow-lines emission, as expected from their positions in the BPT diagrams. (3) The type 1 which reside within the AGN region in the BPT diagrams, are offset to lower [S II]/Hα and [N II]/Hα luminosity ratios, compared to type 2 AGN. This offset is a selection effect, related to the lower AGN/host luminosity selection of the type 2 AGN selected from the SDSS galaxy sample. (4) The [N II]/Hα and [N II]/[S II] ratios in type 1 AGN increase with the host mass, as expected if the mass-metallicity relation of quiescent galaxies holds for the AGN narrow-line region (NLR). (5) The broad lines optical Fe II is higher for a higher [N II]/Hα, at a fixed Lbol and Eddington ratio L/LEdd. This suggests that the broad line region metallicity is also related to the host mass. (6) The fraction of AGN which are low-ionization nuclear emission-line regions (LINERs) increases sharply with decreasing L/LEdd. This fraction is the same for type 1 and type 2 AGN. (7) The BPT position is unaffected by the amount of dust extinction of the optical-UV continuum, which suggests that the extincting dust resides on scales larger than the NLR.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  14. 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

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

    NASA Astrophysics Data System (ADS)

    Stern, J.; Laor, A.

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  17. A compendium of AGN inclinations with corresponding UV/optical continuum polarization measurements

    NASA Astrophysics Data System (ADS)

    Marin, F.

    2014-06-01

    The anisotropic nature of active galactic nuclei (AGN) is thought to be responsible for the observational differences between type-1 (pole-on) and type-2 (edge-on) nearby Seyfert-like galaxies. In this picture, the detection of emission and/or absorption features is directly correlated to the inclination of the system. The AGN structure can be further probed by using the geometry-sensitive technique of polarimetry, yet the pairing between observed polarization and Seyfert type remains poorly examined. Based on archival data, I report here the first compilation of 53 estimated AGN inclinations matched with ultraviolet/optical continuum polarization measurements. Corrections, based on the polarization of broad emission lines, are applied to the sample of Seyfert-2 AGN to remove dilution by starburst light and derive information about the scattered continuum alone. The resulting compendium agrees with past empirical results, i.e. type-1 AGN show low polarization degrees (P ≤ 1 per cent) predominantly associated with a polarization position angle parallel to the projected radio axis of the system, while type-2 objects show stronger polarization percentages (P > 7 per cent) with perpendicular polarization angles. The transition between type-1 and type-2 inclination occurs between 45° and 60° without noticeable impact on P. The compendium is further used as a test to investigate the relevance of four AGN models. While an AGN model with fragmented regions matches observations better than uniform models, a structure with a failed dusty wind along the equator and disc-born, ionized, polar outflows is by far closer to observations. However, although the models correctly reproduce the observed dichotomy between parallel and perpendicular polarization, as well as correct polarization percentages at type-2 inclinations, further work is needed to account for some highly polarized type-1 AGN.

  18. 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.

  19. AGN Feedback in Overdense Environments at z=2.23

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  1. Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations

    NASA Astrophysics Data System (ADS)

    Santini, P.; Rosario, D. J.; Shao, L.; Lutz, D.; Maiolino, R.; Alexander, D. M.; Altieri, B.; Andreani, P.; Aussel, H.; Bauer, F. E.; Berta, S.; Bongiovanni, A.; Brandt, W. N.; Brusa, M.; Cepa, J.; Cimatti, A.; Daddi, E.; Elbaz, D.; Fontana, A.; Förster Schreiber, N. M.; Genzel, R.; Grazian, A.; Le Floc'h, E.; Magnelli, B.; Mainieri, V.; Nordon, R.; Pérez Garcia, A. M.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Riguccini, L.; Rodighiero, G.; Salvato, M.; Sanchez-Portal, M.; Sturm, E.; Tacconi, L. J.; Valtchanov, I.; Wuyts, S.

    2012-04-01

    We compare the average star formation (SF) activity in X-ray selected AGN hosts with a mass-matched control sample of inactive galaxies, including both star forming and quiescent sources, in the 0.5 < z < 2.5 redshift range. Recent observations carried out by PACS, the 60-210 μm photometric camera on board the Herschel Space Observatory, in GOODS-S, GOODS-N and COSMOS allow us to obtain an unbiased estimate of the far-IR luminosity, and hence of the SF properties, of the two samples. Accurate AGN host stellar mass estimates are obtained by decomposing their total emission into the stellar and the nuclear components. We report evidence of a higher average SF activity in AGN hosts with respect to the control sample of inactive galaxies. The level of SF enhancement is modest (~0.26 dex at ~3σ confidence level) at low X-ray luminosities (LX ≲ 1043.5 erg s-1) and more pronounced (0.56 dex at > 10σ confidence level) in the hosts of luminous AGNs. However, when comparing to star forming galaxies only, AGN hosts are found broadly consistent with the locus of their "main sequence". We investigate the relative far-IR luminosity distributions of active and inactive galaxies, and find a higher fraction of PACS detected, hence normal and highly star forming systems among AGN hosts. Although different interpretations are possible, we explain our findings as a consequence of a twofold AGN growth path: faint AGNs evolve through secular processes, with instantaneous AGNaccretion not tightly linked to the current total SF in the host galaxy, while the luminous AGNs co-evolve with their hosts through periods of enhanced AGN activity and star formation, possibly through major mergers. While an increased SF activity with respect to inactive galaxies of similar mass is expected in the latter, we interpret the modest SF offsets measured in low-LX AGN hosts as either a) generated by non-synchronous accretion and SF histories in a merger scenario or b) due to possible connections

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Gallastegui-Aizpun, Unai; Sarajedini, Vicki L.

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

    McHardy, I.

    2016-06-01

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

  7. X-ray AGN Clustering, Bias & Accretion mode

    NASA Astrophysics Data System (ADS)

    Plionis, Manolis; Koutoulidis, Lazaros; Georgantopoulos, Ioannis; Fanidakis, Nikolaos

    2012-09-01

    We present the spatial clustering properties of 1466 X-ray selected AGN compiled from the Chandra CDF-N, CDF-S, eCDF-S, COSMOS and AEGIS fields in the 0.5-8 keV band. The X-ray sources span the redshift interval 0sample of b=2.26+-0.16. Using two different halo bias models, we consistently estimate an average dark-matter host halo mass of M 1.3 (+-0.3) 10^13 h^{-1} MO. The X-ray AGN bias and the corresponding dark-matter host halo mass, are significantly higher than the corresponding values of optically selected AGN (at the same redshifts. The redshift evolution of the X-ray selected AGN bias indicates, in agreement with other recent studies, that a unique dark-matter halo mass does not fit well the bias at all the different redshifts probed. Furthermore, we investigate if there is a dependence of the clustering strength on X-ray luminosity, applying a procedure to disentangle the dependence of clustering on redshift. We find indications for a positive dependence of the clustering length on X-ray luminosity, in the sense that the more luminous sources have a larger clustering length and hence a higher dark-matter halo mass.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  9. ZFOURGE catalogue of AGN candidates: an enhancement of 160-μm-derived star formation rates in active galaxies to z = 3.2

    NASA Astrophysics Data System (ADS)

    Cowley, Michael J.; Spitler, Lee R.; Tran, Kim-Vy H.; Rees, Glen A.; Labbé, Ivo; Allen, Rebecca J.; Brammer, Gabriel B.; Glazebrook, Karl; Hopkins, Andrew M.; Juneau, Stéphanie; Kacprzak, Glenn G.; Mullaney, James R.; Nanayakkara, Themiya; Papovich, Casey; Quadri, Ryan F.; Straatman, Caroline M. S.; Tomczak, Adam R.; van Dokkum, Pieter G.

    2016-03-01

    We investigate active galactic nuclei (AGN) candidates within the FourStar Galaxy Evolution Survey (ZFOURGE) to determine the impact they have on star formation in their host galaxies. We first identify a population of radio, X-ray, and infrared-selected AGN by cross-matching the deep Ks-band imaging of ZFOURGE with overlapping multiwavelength data. From this, we construct a mass-complete (log(M_{{*}}/M_{{⊙}}) ≥9.75), AGN luminosity limited sample of 235 AGN hosts over z = 0.2-3.2. We compare the rest-frame U - V versus V - J (UVJ) colours and specific star formation rates (sSFRs) of the AGN hosts to a mass-matched control sample of inactive (non-AGN) galaxies. UVJ diagnostics reveal AGN tend to be hosted in a lower fraction of quiescent galaxies and a higher fraction of dusty galaxies than the control sample. Using 160 μm Herschel PACS data, we find the mean specific star formation rate of AGN hosts to be elevated by 0.34 ± 0.07 dex with respect to the control sample across all redshifts. This offset is primarily driven by infrared-selected AGN, where the mean sSFR is found to be elevated by as much as a factor of ˜5. The remaining population, comprised predominantly of X-ray AGN hosts, is found mostly consistent with inactive galaxies, exhibiting only a marginal elevation. We discuss scenarios that may explain these findings and postulate that AGN are less likely to be a dominant mechanism for moderating galaxy growth via quenching than has previously been suggested.

  10. The 58-month BAT AGN catalogue: results from the Northern Galactic Cap

    NASA Astrophysics Data System (ADS)

    Vasudevan, R.; Mushotzky, R.; Brandt, N.; Winter, L.; Gandhi, P.; Melendez, M.; Baumgartner, W.

    2014-07-01

    The ongoing Swift/Burst Alert Telescope (BAT) all-sky survey is providing the most complete, hard X-ray selected census of local AGN activity, continually probing to deeper flux limits. I will present recent results from the 58-month BAT catalogue in the Northern Galactic Cap (Galactic latitude b > 50°), probing deeper than previous analyses of the 9-month and 36-month AGN catalogues. Our work includes a comprehensive analysis of the 0.1-200 keV properties (luminosity, absorption, spectral shape, Iron line and reflection properties) of 100 AGN in this sky region. This sample has excellent potential for further multi-wavelength study due to a wide range of archival data already available in other bands, and we propose it as a low-redshift analog to the "deep field" observations of AGNs at higher redshifts (e.g., CDFN/S, COSMOS, Lockman Hole). The stacked spectrum from this representative AGN sample looks remarkably like the Cosmic X-ray background (CXB) spectrum, albeit with a different underlying absorption and Compton reflection distributions than previous CXB synthesis models. I will outline various possibilities of how this sample can be used to further our understanding of local supermassive black hole accretion.

  11. 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.

  12. Intranight polarization variability in radio-loud and radio-quiet AGN

    NASA Astrophysics Data System (ADS)

    Villforth, Carolin; Nilsson, Kari; Østensen, Roy; Heidt, Jochen; Niemi, Sami-Matias; Pforr, Janine

    2009-08-01

    Intranight polarization variability in active galactic nuclei (AGN) has not been studied extensively so far. Studying the variability in polarization makes it possible to distinguish between different emission mechanisms. Thus, it can help answering the question if intranight variability in radio-loud and radio-quiet AGN is of the same or of fundamentally different origin. In this paper, we investigate intranight polarization variability in AGN. Our sample consists of 28 AGN at low to moderate redshifts (0.048 <= z <= 1.036), 12 of which are radio-quiet quasars (RQQs) and 16 are radio-loud blazars. The subsample of blazars consists of eight flat-spectrum radio-quasars (FSRQs) and eight BL Lac objects. Each AGN was observed for a time-span of ~4h in the R band to measure polarization and variability. Using statistical methods, we determine duty cycles for polarized emission and polarization intranight variability. We find clear differences between the two samples. A majority of the radio-loud AGN show moderate to high degrees of polarization, more than half of them also show variability in polarization. There seems to be a dividing line for polarization intranight variability at P ~ 5 per cent over which all objects vary in polarization. We did not find clear correlations between the strength of the variability and the redshift or degree of polarization. Only two out of 12 RQQs show polarized emission, both at levels of P < 1 per cent. The lack of polarization intranight variability in radio-quiet AGN points towards accretion instabilities being the cause for intranight flux variability whereas the high duty cycle of polarization variability in radio-loud objects is more likely caused by instabilities in the jet or changes of physical conditions in the jet plasma. We were able to constrain the time-scale of the detected variations to >4 h. Further studies of intranight polarization variability will be necessary to reveal exact physical conditions behind this

  13. 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.

  14. 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.

  15. AGN Population in Hickson Compact Groups. I. Data and Nuclear Activity Classification

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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 Hα luminosity of 7.1 × 1039 erg s-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 Martínez 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Micic, Miroslav; Martinović, Nemanja; Sinha, Manodeep

    2016-09-01

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

  18. 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.

  19. The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses

    NASA Astrophysics Data System (ADS)

    Leauthaud, Alexie; J. Benson, Andrew; Civano, Francesca; L. Coil, Alison; Bundy, Kevin; Massey, Richard; Schramm, Malte; Schulze, Andreas; Capak, Peter; Elvis, Martin; Kulier, Andrea; Rhodes, Jason

    2015-01-01

    Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter haloes in which they reside is key to constraining how black hole fuelling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modelling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. In this work, we show that better constraints can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to the fiducial stellar-to-halo mass relation (SHMR) derived for all galaxies, irrespective of nuclear activity. Our technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone. Using 382 moderate luminosity X-ray AGN at z < 1 from the COSMOS field, we report the first measurements of weak gravitational lensing from an X-ray-selected sample. Comparing this signal to predictions from the global SHMR, we find that, contrary to previous results, most X-ray AGN do not live in medium size groups - nearly half reside in relatively low mass haloes with M200b ˜ 1012.5 M⊙. The AGN occupation function is well described by the same form derived for all galaxies but with a lower normalization - the fraction of haloes with AGN in our sample is a few per cent. The number of AGN satellite galaxies scales as a power law with host halo mass with a power-law index α = 1. By highlighting the relatively `normal' way in which moderate luminosity X-ray AGN hosts occupy haloes, our results suggest that the environmental signature of distinct fuelling modes for luminous quasars compared to moderate luminosity X-ray AGN is less obvious than previously claimed.

  20. PRIMUS: THE DEPENDENCE OF AGN ACCRETION ON HOST STELLAR MASS AND COLOR

    SciTech Connect

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

    2012-02-10

    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{sub 2-10keV} = 10{sup 42-44} erg s{sup -1} within a parent sample of {approx}25,000 galaxies at 0.2 < z < 1.0 over {approx}3.4 deg{sup 2} and to i {approx} 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< log M{sub *}/M{sub sun}<12 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 {approx} 1 and the present day and is moderately enhanced (factor {approx}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.

  1. They Call Me Agnes: A Crow Narrative Based on the Life of Agnes Yellowtail Deernose.

    ERIC Educational Resources Information Center

    Voget, Fred W.; Mee, Mary K.

    This book is about life on the Crow Indian Reservation from around 1910 to the present and is based on the personal experiences of Donnie and Agnes Deernose. Following Donnie's death, Agnes became the principal narrator of the book. The Crow Indian Reservation is situated between Billings, Montana, and Sheridan, Wyoming. More so than any other…

  2. The Evolutionary Connection Bewtween z~2-3 Submillimeter Galaxies and AGN as Probed by Molecular Gas Excitation

    NASA Astrophysics Data System (ADS)

    Sharon, Chelsea E.; Riechers, Dominik A.; Carilli, Chris Luke; Hodge, Jacqueline; Walter, Fabian

    2016-01-01

    Theoretical work has suggested that active galactic nuclei (AGN) play an important role in quenching star formation in massive galaxies. Direct evidence for AGN affecting the molecular ISM has so far been limited to detections of molecular outflows in low-redshift systems and extreme excitation regions which represent a tiny fraction of the total gas. Indirect evidence for AGN's impact on their host galaxies' cold gas phase may be provided by measurements of the gas excitation and dynamics. At z~2-3, the peak epoch of star formation and AGN activity, previous observations of the CO(1-0) line revealed that submillimeter galaxies (SMGs) have multi-phase molecular gas, including substantial reservoirs of cold-phase gas. However, the entirety of the molecular gas in AGN-host galaxies appears highly excited, potentially supporting an evolutionary connection between these two populations. I will present a new VLA sample that nearly doubles the number of CO(1-0) detections in z~2-3 SMGs and AGN-host galaxies that allows us to better compare the cold gas properties of these systems and further investigate evidence for the effects of AGN on the star-forming molecular gas.

  3. THE OPTX PROJECT. IV. HOW RELIABLE IS [O III] AS A MEASURE OF AGN ACTIVITY?

    SciTech Connect

    Trouille, L.; Barger, A. J.

    2010-10-10

    We compare optical and hard X-ray identifications of active galactic nuclei (AGNs) using a uniformly selected (above a flux limit of f{sub 2-8{sub keV}} = 3.5 x 10{sup -15} erg cm{sup -2} s{sup -1}) and highly optically spectroscopically complete (>80% for f{sub 2-8{sub keV}} > 10{sup -14} erg cm{sup -2} s{sup -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]{lambda}5007 (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 {approx}3 (1{sigma}). 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.

  4. Modelling galaxy and AGN evolution in the infrared: black hole accretion versus star formation activity

    NASA Astrophysics Data System (ADS)

    Gruppioni, C.; Pozzi, F.; Zamorani, G.; Vignali, C.

    2011-09-01

    We present a new backward evolution model for galaxies and active galactic nuclei (AGNs) in the infrared (IR). What is new in this model is the separate study of the evolutionary properties of different IR populations (i.e. spiral galaxies, starburst galaxies, low-luminosity AGNs, 'unobscured' type 1 AGNs and 'obscured' type 2 AGNs) defined through a detailed analysis of the spectral energy distributions (SEDs) of large samples of IR-selected sources. The evolutionary parameters have been constrained by means of all the available observables from surveys in the mid- and far-IR (source counts, redshift and luminosity distributions, luminosity functions). By decomposing the SEDs representative of the three AGN classes into three distinct components (a stellar component emitting most of its power in the optical/near-IR, an AGN component due to the hot dust heated by the central black hole peaking in the mid-IR, and a starburst component dominating the far-IR spectrum), we have disentangled the AGN contribution to the monochromatic and total IR luminosity emitted by different populations considered in our model from that due to star formation activity. We have then obtained an estimate of the total IR luminosity density [and star formation density (SFD) produced by IR galaxies] and the first ever estimate of the black hole mass accretion density (BHAR) from the IR. The derived evolution of the BHAR is in agreement with estimates from X-rays, though the BHAR values we derive from the IR are slightly higher than the X-ray ones. Finally, we have simulated source counts, redshift distributions, and SFD and BHAR that we expect to obtain with the future cosmological surveys in the mid-/far-IR that will be performed with the JWST-MIRI and SPICA-SAFARI. Outputs of the model are available online.1

  5. 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.

  6. Nuclear mid-infrared properties of nearby low-luminosity AGN

    NASA Astrophysics Data System (ADS)

    Asmus, D.; Hönig, S. F.; Gandhi, P.; Smette, A.; Duschl, W. J.

    2012-07-01

    We present ground-based high-spatial resolution mid-infrared (MIR) observations of 20 nearby low-luminosity AGN (LLAGN) with VLT/VISIR and the preliminary analysis of a new sample of 10 low-luminosity Seyferts observed with Gemini/Michelle. LLAGN are of great interest because these objects are the most common among active galaxies, especially in the nearby universe. Studying them in great detail makes it possible to investigate the AGN evolution over cosmic timescale. Indeed, many LLAGN likely represent the final stage of an AGN's lifetime. We show that even at low luminosities and accretion rates nuclear unresolved MIR emission is present in most objects. Compared to lower spatial resolution Spitzer/IRS spectra, the high-resolution MIR photometry exhibits significantly lower fluxes and different PAH emission feature properties in many cases. By using scaled Spitzer/IRS spectra of typical starburst galaxies, we show that the star formation contribution to the 12 μm emission is minor in the central parsecs of most LLAGN. Therefore, the observed MIR emission in the VISIR and Michelle data is most likely emitted by the AGN itself, which, for higher luminosity AGN, is interpreted as thermal emission from a dusty torus. Furthermore, the 12 /amemission of the LLAGN is strongly correlated with the absorption corrected 2-10 keV luminosity and the MIR- X-ray correlation found previously for AGN is extended to a range from 1040 to 1045 erg/s. This correlation is independent of the object type, and in particular the low-luminosity Seyferts observed with Michelle fall exactly on the power-law fit valid for brighter AGN. In addition, no dependency of the MIR-X-ray ratio on the accretion rate is found. These results are consistent with the unification model being applicable even in the probed low-luminosity regime.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Moran, Edward C.

    2016-04-01

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

  9. 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.

  10. 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

  11. 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.

  12. The high angular resolution view of local X-ray selected AGN in the mid-infrared

    NASA Astrophysics Data System (ADS)

    Gandhi, Poshak; Asmus, D.; Hönig, S. F.; Smette, A.; Duschl, W. J.; Matsuta, K.; Ichikawa, K.; Ueda, Y.; Terashima, Y.; Gilli, R.; Comastri, A.; Vignali, C.

    2012-09-01

    Hard X-ray and mid-infrared observations probe the peaks in broadband spectra of active galactic nucle (AGN), sampling the bulk of their accretion energy. But bolometric emission measurements of Seyfert galaxies can be strongly biased by unresolved nuclear stellar emission. Disentangling these components using emission line proxies for the intrinsic AGN power suffers from various uncertainties. Here, we show that fundamental new insights into AGN are enabled by using high angular resolution observations of Seyferts with the largest telescopes currently available. We have imaged the 9 month Swift/BAT selected AGN sample using the VLT, Gemini and Subaru at their diffraction-limit at 12°. Collecting all high angular resolution data yields a large database of 150 AGN of all types with a point-like detected nucleus. This sample serves as a benchmark for studies on unification issues and accurate (unbiased) AGN bolometric corrections. We discuss some key results, including new inferences on the structures of Seyfert nuclei from the enlarged infrared/Xray correlation and show that the MIR to X-ray flux ratio is independent of the Eddington fraction (lEdd) over about 4 orders of magnitude down to lEdd 10^{-4} at least, which appears to be the threshold below which accretion properties change.

  13. 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

  14. Long-term variability of AGN at hard X-rays

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Aims: 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 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 using the first 9 months of BAT data, we study the amplitude of the variations and their dependence on subclass and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey. Results: About 80% of the AGN in the sample are found to exhibit significant variability on month-to-year time scales. In particular, radio loud sources are the most variable, and Seyfert 1.5-2 galaxies are slightly more variable than Seyfert 1, while absorbed and unabsorbed objects show similar timing properties. The amplitude of the variations and their energy dependence are incompatible with variability being driven at hard X-rays by changes in the absorption column density. In general, the variations in the 14-24 and 35-100 keV bands are correlated well, suggesting a common origin to 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 a time scale of a month. In addition, sources with harder spectra are found to be more variable than softer ones, unlike what it is observed below 10 keV. These properties are generally

  15. Radio galaxies in ZFOURGE/NMBS: no difference in the properties of massive galaxies with and without radio-AGN out to z = 2.25

    NASA Astrophysics Data System (ADS)

    Rees, G. A.; Spitler, L. R.; Norris, R. P.; Cowley, M. J.; Papovich, C.; Glazebrook, K.; Quadri, R. F.; Straatman, C. M. S.; Allen, R.; Kacprzak, G. G.; Labbe, I.; Nanayakkara, T.; Tomczak, A. R.; Tran, K.-V.

    2016-01-01

    In order to reproduce the high-mass end of the galaxy mass distribution, some process must be responsible for the suppression of star formation in the most massive of galaxies. Commonly active galactic nuclei (AGN) are invoked to fulfil this role, but the exact means by which they do so is still the topic of much debate, with studies finding evidence for both the suppression and enhancement of star formation in AGN hosts. Using the ZFOURGE (FourStar Galaxy Evolution) and NMBS (Newfirm Medium Band Survey) galaxy surveys, we investigate the host galaxy properties of a mass-limited (M ≥ 1010.5 M⊙), high-luminosity (L1.4 > 1024 W Hz-1) sample of radio-loud AGN to a redshift of z = 2.25. In contrast to low-redshift studies, which associate radio-AGN activity with quiescent hosts, we find that the majority of z > 1.5 radio-AGN are hosted by star-forming galaxies. Indeed, the stellar populations of radio-AGN are found to evolve with redshift in a manner that is consistent with the non-AGN mass-similar galaxy population. Interestingly, we find that the radio-AGN fraction is constant across a redshift range of 0.25 ≤ z < 2.25, perhaps indicating that the radio-AGN duty cycle has little dependence on redshift or galaxy type. We do however see a strong relation between the radio-AGN fraction and stellar mass, with radio-AGN becoming rare below ˜1010.5 M⊙ or a halo mass of 1012 M⊙. This halo-mass threshold is in good agreement with simulations that initiate radio-AGN feedback at this mass limit. Despite this, we find that radio-AGN host star formation rates are consistent with the non-AGN mass-similar galaxy sample, suggesting that while radio-AGN are in the right place to suppress star formation in massive galaxies they are not necessarily responsible for doing so.

  16. 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.

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

    SciTech Connect

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

    2014-04-01

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

  18. 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.

  19. Studies of the black hole mass and the eddington rate of AGNs

    NASA Astrophysics Data System (ADS)

    Bao, Y. Y.; Zhang, X.; Chen, L. E.; Zhang, H. J.; Peng, Z. Y.; Zheng, Y. G.

    2008-04-01

    Many people have discussed the property of AGNs (active galactic nuclei). The variation of spectrum, the correlation of multi-wave bands and the property of polarization give good information for studying intrinsic correlation of components and its position. To date, the redshift and the Eddington rate and the masses of black hole are the basic properties of active galactic nuclei. In this paper, firstly calculated the mass of black hole and the Eddington rate of 172 samples using the reverberation mapping method, secondly statistical distribution of the black hole masses and the Eddington rate of Seyfert Galaxies and Quasars, thirdly investigated the relation between redshift and Eddington rate and analysed the relation between Eddington rate and the black hole mass and discussed the relation between the redshift and the masses of black hole as well as the relation between the redshift and the Eddington rate, since the evolution essential of AGNs is the change on the timescales of the universe, and the redshift plays an important role in the evolution of AGNs. From these analyses, this paper found that the black hole masses and the redshift of AGNs change with the development of Eddington rate. Through these results, the paper has made an initial statistical research for the AGNs evolution, and found the transformation from Quasar to Seyfert galaxy.

  20. Feeding and feeback: The impact of AGN on the circumgalactic medium.

    NASA Astrophysics Data System (ADS)

    Ellison, Sara

    2014-10-01

    A galaxy's history is shaped by the fuelling and feedback of gas both from and into the circumgalactic medium (CGM). The importance of the CGM in low z galaxies has been unequivocally demonstrated in recent years, thanks to the availability of COS and a coupling with large galaxy surveys. These studies have traced the HI and metals out to several hundred kpc, revealing a rich and extended medium around star-forming galaxies. However, the impact of AGN on this CGM is almost completely unknown. We propose to observe the CGM probed by background QSOs at impact parameters up to 175 kpc around 10 moderately high luminosity AGN-dominated galaxies selected from the SDSS. By comparing with an archival sample of non-AGN in the same stellar mass, redshift and impact parameter regime we will investigate 1) the extent of the halo, its velocity structure and its metal enrichment and 2) the ionization structure and physical properties of the AGN galaxies' CGM. These objectives are both scientifically timely and yet only recently achievable, thanks to the combination of COS's high sensitivity, the compilation of large numbers of local AGN, and the development of sophisticated ionization models by our team.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  2. First Results from the NuSTAR Survey of Swift/BAT AGN

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Launch of the first focusing hard X-ray telescope, the Nuclear Spectroscopic Telescope Array (NuSTAR), 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 higher sensitivity than any other instrument operating in that bandpass. As a part of its long-term Extragalactic Surveys program, NuSTAR will survey the nearby population of AGN detected at hard X-ray energies in the Swift/BAT all-sky survey. We present a survey of ~100 Swift/BAT AGN observed in the first two years of NuSTAR operation. A short 15-25 ks NuSTAR exposure of a source detected with the Swift/BAT instrument provides a sufficiently detailed hard X-ray spectrum to provide well-constrained model parameters for each one individually. This sample forms an atlas of the best hard X-ray spectra available to date for a substantial number of AGN. Assuming a range of spectral models, both phenomenological and physically motivated, we determine the distributions of spectral parameters, such as the spectral index, absorption column, reflection strength and iron line equivalent width. We discuss the implications for the local Seyfert 2 population and the limitations of the current results. We also highlight more detailed studies of particular AGN, and preliminary results on multiplicity and variability in the hard X-ray band.

  3. Correlations of Circumnuclear Water Maser Luminosity with AGN Activity and SMBH Mass

    NASA Astrophysics Data System (ADS)

    Mei, Ming-Yi Jeffrey; Zaw, I.; Greenhill, L. J.

    2014-01-01

    We examine 53 water masers, the only known resolvable tracers of gas in the sub-parsec disks of active galactic nuclei (AGN). We test if there is a relationship between the isotropic maser luminosity and black hole mass and AGN activity. Black hole mass is estimated from velocity dispersion, sigma, and AGN bolometric luminosity from [OIII]5007 luminosity, from SDSS spectra. The maser are sorted, based on their radio spectra, into disk-type masers, located in the accretion disk, jet-type masers, located in a jet/outflow, or other-type masers, where the location of the masers is unclear. The maser luminosity is fit against black hole mass and AGN luminosity and compared with the theoretical predictions from Neufeld and Maloney (1995). This builds on the result from Zhu et al. (2011) with a doubled sample size and fitting for both variables at the same time. The dependence of isotropic maser luminosity of the disk and jet masers on black hole mass and AGN luminosity agree within error to the model, while the "other" masers show no correlation.

  4. Anomalous H-beta Variability in the 2014 NGC 5548 AGN-STORM Monitoring Campaign

    NASA Astrophysics Data System (ADS)

    Pei, Liuyi; AGN STORM Collaboration

    2016-06-01

    Reverberation mapping programs generally find that the continuum and H-beta flux variations in AGNs are well correlated. In the 2014 AGN STORM monitoring program for NGC 5548, we observed a distinct decorrelation of the emission-line light curves from the AGN continuum light curve during the second half of the six-month campaign. This effect was first detected for the C IV, Ly a, HeII 1640 and SiIV/OIV] 1400 lines in Hubble Space Telescope data, then observed for the H-beta line in ground-based data taken during the same monitoring period. We present measurements of the H-beta lags, equivalent width variations, and line responsivity changes during our campaign. We show that the AGN demonstrated unusual behavior in that the broad H-beta responsivity to flux variations decreased significantly during the second half of the campaign. The discovery of this decorrelation phenomenon was made possible by the high cadence and long duration of our monitoring campaign. More multi-wavelength observing campaigns with high sampling cadence, high signal-to-noise ratio, and long temporal baseline are needed for other AGNs in order to determine the prevalence of this phenomenon and to understand its physical origin.

  5. Do Radio Jets Contribute to Driving Ionized Gas Outflows in Moderate Luminosity Type 2 AGN?

    NASA Astrophysics Data System (ADS)

    Fowler, Julia; Sajina, Anna; Lacy, Mark

    2016-01-01

    This poster examines the role of AGN-driven feedback in low to intermediate power radio galaxies. We begin with [OIII] measurements of ionized gas outflows in 29 moderate AGN-luminosity z~0.3-0.7 dust-obscured Type 2 AGN. We aim to examine the relative role of the AGN itself, of star-formation and of nascent radio jets in driving these outflows. The strength of the AGN and star formation are based on the [OIII] luminosities, and the far-IR luminosities respectively. For the radio jets, we present multi-frequency radio (X, S, and L-bands) JVLA imaging of our sample, which allows us both to constrain the overall radio power, but also look for signatures of young radio sources, including Giga-hertz Peaked Spectrum (GPS) sources, as well as small-scale jets. While radio jet-driven outflows are well known for powerful radio-loud galaxies, this study allows us to constrain the degree to which this mechanism is significant at more modest radio luminosities of L5GHz~10^22-25 W/Hz.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  7. The evolution of AGN's at x ray wavelengths

    NASA Technical Reports Server (NTRS)

    Maccacaro, Tommaso; Dellaceca, R.; Gioia, I. M.; Stocke, J. T.; Wolter, A.

    1992-01-01

    The cosmological evolution and the Luminosity Function (LF) of x-ray selected Active Galactic Nuclei (AGN) are discussed. The sample used is extracted from the Einstein Observatory Extended Medium Sensitivity Survey (EMSS) and consists of more than 420 objects. Preliminary results from the Rosat all sky survey data confirm the correctness of the optical identification of the EMSS sources, thus giving confidence to the results obtained from the analysis of the AGN sample. The XLF observed at different redshifts gives direct evidence of cosmological evolution. Data were analyzed within the framework of luminosity evolution models and the two most common evolutionary forms were considered. Luminosity dependent evolution is required if the evolution function has the exponential form, whereas the simpler pure luminosity evolution model is still acceptable if the evolution function has the power law form. Using the whole sample of objects the number counts and the devolved XLF were derived. A comparison of the EMSS Data with preliminary Rosat results indicates an overall agreement.

  8. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  12. A multi-wavelength survey of AGN in massive clusters: AGN distribution and host galaxy properties

    NASA Astrophysics Data System (ADS)

    Klesman, Alison J.; Sarajedini, Vicki L.

    2014-07-01

    We investigate the effect of environment on the presence and fuelling of active galactic nuclei (AGN) by identifying galaxies hosting AGN in massive galaxy clusters and the fields around them. We have identified AGN candidates via optical variability (178), X-ray emission (74), and mid-IR SEDs (64) in multi-wavelength surveys covering regions centred on 12 galaxy clusters at redshifts 0.5 < z < 0.9. In this paper, we present the radial distribution of AGN in clusters to examine how local environment affects the presence of an AGN and its host galaxy. While distributions vary from cluster to cluster, we find that the radial distribution of AGN generally differs from that of normal galaxies. X-ray-selected AGN candidates appear to be more centrally concentrated than normal galaxies in the inner 20 per cent of the virial radius, while becoming less centrally concentrated in the outer regions. Mid-IR-selected AGN are less centrally concentrated overall. Optical variables have a similar distribution to normal galaxies in the inner regions, then become somewhat less centrally concentrated farther from the cluster centre. The host galaxies of AGN reveal a different colour distribution than normal galaxies, with many AGN hosts displaying galaxy colours in the `green valley' between the red sequence and blue star-forming normal galaxies. This result is similar to those found in field galaxy studies. The colour distribution of AGN hosts is more pronounced in disturbed clusters where minor mergers, galaxy harassment, and interactions with cluster substructure may continue to prompt star formation in the hosts. Among normal galaxies, we find that galaxy colours become generally bluer with increasing cluster radius, as is expected. However, we find no relationship between host galaxy colour and cluster radius among AGN hosts, which may indicate that processes related to the accreting supermassive black hole have a greater impact on the star-forming properties of the host galaxy

  13. γ-Ray Generation in Microquasars: the link with AGN

    NASA Astrophysics Data System (ADS)

    Latham, I. J.; Aye, K.-M.; Brown, A. M.; Chadwick, P. M.; Hadjichristidis, C. N.; Le Gallou, R.; McComb, T. J. L.; Nolan, S. J.; Orford, K. J.; Osborne, J. L.; Noutsos, A.; Rayner, S. M.

    2005-02-01

    The link between the physical processes responsible for high energy emission from relativistic jets in AGN and microquasars is investigated. A Fortran code based on an existing inhomogeneous, synchrotron self-Compton (SSC) model, for AGN is presented. The code is then applied to the AGN 3C 279 and the microquasar LS5039. Spectral energy distributions (SED's) are presented.

  14. 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.

  15. FE Features in Highly Obscured AGN

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.

    1999-01-01

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

  16. 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).

  17. Host galaxies of luminous type II AGN: Winds, shocks, and comparisons to The SAMI Galaxy Survey

    NASA Astrophysics Data System (ADS)

    McElroy, Rebecca; Croom, Scott; Pracy, Michael; SAMI Galaxy Survey Team

    2016-01-01

    We present IFS observations of luminous (log(L[O III]/L⊙) > 8.7) local (z < 0.11) type II AGN, and demonstrate that winds are ubiquitous within this sample and have a direct influence on the ISM of the host galaxies. We use both non-parametric (e.g. line width and asymmetry) and multi-Gaussian fitting to decompose the complex emission profiles close to the AGN. We find line widths containing 80% flux in the range 400 - 1600 km/s with a mean of 790 ± 90 km/s, such high velocities are strongly suggestive that these AGN are driving ionized outflows. Additionally, multi-Gaussian fitting reveals that 14/17 of our targets require 3 separate kinematic components in the ionized gas in their central regions. The broadest components of these fits have FWHM = 530 - 2520 km/s, with a mean value of 920 ± 50 km/s. By simultaneously fitting both the Hβ/[O III] and Hα/[N II] complexes we construct ionization diagnostic diagrams for each component. 13/17 of our galaxies show a significant (> 95 %) correlation between the [N II]/Hα ratio and the velocity dispersion of the gas. Such a correlation is the natural consequence of a contribution to the ionization from shock excitation and we argue that this demonstrates that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies. In addition, we use stellar absorption features to measure kinematics for these AGN host galaxies and those of a control sample selected from the SAMI Galaxy Survey to search for evidence of these luminous AGN being preferentially hosted by disturbed or merging systems.

  18. 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.

  19. 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

  20. Coordinated Multifrequency Observations of Variable Agns

    NASA Astrophysics Data System (ADS)

    Worrall, Diana M.

    1984-07-01

    Our ME measurements of BL Lac objects to date, coordinated with observations in other frequency bands, show positive spectral curvature within the infrared to ultraviolet energy range (Worrall and Bruhweiler 1982). There is evidence that this component is synchrotron radiation. In order to fit the spectral measurements, we find that relativistic beaming is an essential ingredient of simple models not involving electron reacceleration. It is important to discover to what extent this is observationally true of all BL Lac objects, and to then compare with expectations of the distribution in Lorentz factor derived from geometrical arguments. Our sample of BL Lac objects so far numbers 5. There are 17 other BL Lac objects for which IUE observations are listed in the master catalogue. However, many of these objects are so heavily contaminated by a galactic component in the visual and near infrared that the data cannot be usefully employed for our purpose. Also, to our knowledge, the necessary nearly simultaneous coverage in the infrared and visual only exists for 6 of these 17. The near-simultaneity is a vital element, since these active galactic nuclei (AGNs) tend to exhibit different flux variability characteristics in the different available wavebands. We present a target list primarily composed of BL Lac objects, but including 3 QSOs. Conclusions from non-simultaneous multifrequency observations by Malkan and Sargent (1982) suggest that one difference between QSOs and BL Lacs is that the non-thermal infrared to ultraviolet QSO flux does not appear to exhibit curvature. We would like to investigate this more closely, with simultaneous observations. We propose to coordinate all our observations with radio, millimeter, infrared and visual wavelength coverage and have calculated time periods during which this will be possible. Final target selection from our list of visually variable objects will be based on their magnitudes just prior to shift allotment.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  2. X-ray surveys - Weighting the dark matter haloes of X-ray AGN: towards a physical description of the accretion history of the Universe

    NASA Astrophysics Data System (ADS)

    Georgakakis, Antonis; Mountrichas, G.; Fanidakis, N.; Finoguenov, A.; Aegis Collaboration

    2012-09-01

    The masses of the dark matter haloes in which AGN live is powerful diagnostic of the conditions under which supermassive black holes form and evolve across cosmic time. A new clustering estimation method will be presented which requires spectroscopy only for the AGN and uses photometric redshift probability density functions for galaxies to determine the projected real-space AGN/galaxy cross-correlation function. Our method is superior to traditional AGN clustering estimators (e.g. auto-correlation function) because (i) random errors are significantly suppressed when counting AGN/galaxy pairs, (ii) the impact of sample variance is minimized, and (iii) the requirements for spectroscopy are minimal; only spectroscopic redshift measurements for the AGN are needed. This method is applied to the combined AEGIS, COSMOS and ECDFS fields to infer the bias and dark matter halo mass of moderate luminosity (Lx~10^43 erg/s/cm^2) X-ray AGN at z~1 (total of 400). Predictions from the GALFORM semi-analytic model will be compared to the observations to show that a combination of hot and cold-gas accretion (the latter triggered by disk instabilities in spirals rather than mergers) reproduce well the clustering properties of X-ray AGN over a range of redshifts and luminosities.

  3. 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.

  4. 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.

  5. The Optical and X-ray Spectral Properties of the Swift BAT-detected AGNs

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.; Mushotzky, R.; Lewis, K.; Veilleux, S.; Koss, M.; Keeney, B.

    2010-01-01

    The Swift Burst Alert Telescope (BAT), while not focused on a Gamma-ray burst, conducts an all-sky survey in the 14 - 195 keV band. After the first 9 months, the BAT has detected a sample of 153 local (z 0.03) AGN at a flux limit of a few times 10-11 erg/s/cm-2 (Tueller et al. 2007). Since the AGN were detected at very high X-ray energies, they are an unbiased sample towards Compton thin AGN. We present the X-ray and optical spectral properties of a sample of the BAT AGN, including optical spectra obtained from the literature, SDSS, and our own KPNO 2.1-m observations. Among our results, we show that the optically identified Seyfert 1s and 2s have the same distribution of X-ray and [O III] luminosities. We also find that [O III] luminosity is not well-correlated with the hard X-rays and therefore not a good indicator of bolometric luminosity, supporting the results of Melendez et al. (2008).

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  7. 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.

  8. Mid-IR Observations of AGN

    NASA Astrophysics Data System (ADS)

    Packham, Christopher C.; Alonso Herrero, Almudena; Levenson, Nancy A.; Piratas AGN Group

    2016-01-01

    We present new observations of AGN, predominantly from the 10.4m GranTeCan. These observations are modeled and interpreted within the context of the clumpy torus models. In this poster we present our recent results and interpretation of the model outputs.

  9. 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…

  10. Massive molecular outflows and evidence for AGN feedback from CO observations

    NASA Astrophysics Data System (ADS)

    Cicone, C.; Maiolino, R.; Sturm, E.; Graciá-Carpio, J.; Feruglio, C.; Neri, R.; Aalto, S.; Davies, R.; Fiore, F.; Fischer, J.; García-Burillo, S.; González-Alfonso, E.; Hailey-Dunsheath, S.; Piconcelli, E.; Veilleux, S.

    2014-02-01

    We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1-0) observations of local ultra-luminous infrared galaxies (ULIRGs) and quasar-hosts: a clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1-0) kinematics of four out of seven sources, with measured outflow rates of several 100 M⊙ yr-1. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies. We find that starburst-dominated galaxies have an outflow rate comparable to their star formation rate (SFR), or even higher by a factor of ~2-4, implying that starbursts can indeed be effective in removing cold gas from galaxies. Nevertheless, our results suggest that the presence of an active galactic nucleus (AGN) can boost the outflow rate by a large factor, which is found to increase with the LAGN/Lbol ratio. The gas depletion time scales due to molecular outflows are anti-correlated with the presence and luminosity of an AGN in these galaxies, and range from a few hundred million years in starburst galaxies down to just a few million years in galaxies hosting powerful AGNs. In quasar hosts, the depletion time scales due to the outflow are much shorter than the depletion time scales due to star formation. We estimate the outflow kinetic power and find that, for galaxies hosting powerful AGNs, it corresponds to about 5% of the AGN luminosity, as expected by models of AGN feedback. Moreover, we find that momentum rates of about 20 LAGN/c are common among the AGN-dominated sources in our sample. For "pure" starburst galaxies, our data tentatively support models in which outflows are mostly momentum-driven by the radiation pressure from young stars onto dusty clouds. Overall, our results indicate that, although starbursts are effective in powering

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  13. Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

    SciTech Connect

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

    2014-06-20

    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  15. The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities

    NASA Astrophysics Data System (ADS)

    Arav, Nahum

    2009-07-01

    AGN outflows are increasingly invoked as a major contributor to the formation and evolution of supermassive black holes, their host galaxies, the surrounding IGM, and cluster cooling flows. Our HST/COS proposal will determine reliable absolute chemical abundances in six AGN outflows, which influences several of the processes mentioned above. To date there is only one such determination, done by our team on Mrk 279 using 16 HST/STIS orbits and 100 ksec of FUSE time. The advent of COS and its high sensitivity allows us to choose among fainter objects at redshifts high enough to preclude the need for FUSE. This will allow us to determine the absolute abundances for six AGN {all fainter than Mrk 279} using only 40 HST COS orbits. This will put abundances studies in AGN on a firm footing, an elusive goal for the past four decades. In addition, prior FUSE observations of four of these targets indicate that it is probable that the COS observations will detect troughs from excited levels of C III. These will allow us to measure the distances of the outflows and thereby determine their kinetic luminosity, a major goal in AGN feedback research. We will use our state of the art column density extraction methods and velocity-dependent photoionization models to determine the abundances and kinetic luminosity. Previous AGN outflow projects suffered from the constraints of deciding what science we could do using ONE of the handful of bright targets that were observable. With COS we can choose the best sample for our experiment. As an added bonus, most of the spectral range of our targets has not been observed previously, greatly increasing the discovery phase space.

  16. Molecular Gas Excitation and the Evolutionary Connection Between Submillimeter Galaxies and AGN at z~2-3

    NASA Astrophysics Data System (ADS)

    Sharon, Chelsea; Riechers, Dominik Alexander; Carilli, Christopher; Hodge, Jacqueline; Walter, Fabian

    2015-08-01

    Theoretical work has suggested that active galactic nuclei (AGN) may play an important role in quenching star formation in massive galaxies. Due to sensitivity demands, direct evidence for AGN affecting the molecular ISM (the gas phase that fuels star formation) has so far been limited to detections of molecular outflows in low-redshift systems. Indirect evidence for an interplay between AGN and their host galaxies' cold gas phase may be provided by measurements of the gas excitation (and dynamics). At z~2-3, the peak epoch of star formation and AGN activity, previous observations of the CO(1-0) line revealed that submillimeter galaxies have substantial reservoirs of cold molecular gas. However, the molecular gas in AGN-host galaxies appears highly excited, potentially supporting an evolutionary connection between these two populations. We will present a new larger Karl G. Jansky Very Large Array sample that nearly doubles the number of CO(1-0) detections in z~2-3 submillimeter galaxies and AGN-host galaxies with existing CO(3-2) detections (from 13 to 23, plus four new upper limits) that allows us to better compare the low-excitation molecular gas properties of these systems and further investigate potential evidence for gas excitation due to active black holes.

  17. 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.

  18. Clustering of moderate luminosity X-ray-selected type 1 and type 2 AGNs at z ∼ 3

    SciTech Connect

    Allevato, V.; Finoguenov, A.; Civano, F.; Cappelluti, N.; Shankar, F.; Miyaji, T.; Hasinger, G.; Gilli, R.; Zamorani, G.; Comastri, A.; Lanzuisi, G.; Salvato, M.; Elvis, M.; Silverman, J.

    2014-11-20

    We investigate, for the first time at z ∼ 3, the clustering properties of 189 Type 1 and 157 Type 2 X-ray active galactic nuclei (AGNs) of moderate luminosity ((L {sub bol}) = 10{sup 45.3} erg s{sup –1}), with photometric or spectroscopic redshifts in the range 2.2 < z < 6.8. These samples are based on Chandra and XMM-Newton data in COSMOS. We find that Type 1 and Type 2 COSMOS AGNs at z ∼ 3 inhabit DMHs with typical mass of log M{sub h} = 12.84{sub −0.11}{sup +0.10} and 11.73{sub −0.45}{sup +0.39} h {sup –1} M {sub ☉}, respectively. This result requires a drop in the halo masses of Type 1 and 2 COSMOS AGNs at z ∼ 3 compared to z ≲ 2 XMM-COSMOS AGNs with similar luminosities. Additionally, we infer that unobscured COSMOS AGNs at z ∼ 3 reside in 10 times more massive halos compared to obscured COSMOS AGNs, at the 2.6σ level. This result extends to z ∼ 3 the results found in COSMOS at z ≲ 2, and rules out the picture in which obscuration is purely an orientation effect. A model which assumes that the AGNs activity is triggered by major mergers is quite successful in predicting both the low halo mass of COSMOS AGNs and the typical mass of luminous SDSS quasars at z ∼ 3, with the latter inhabiting more massive halos respect to moderate luminosity AGNs. Alternatively we can argue, at least for Type 1 COSMOS AGNs, that they are possibly representative of an early phase of fast (i.e., Eddington limited) BH growth induced by cosmic cold flows or disk instabilities. Given the moderate luminosity, these new fast growing BHs have masses of ∼10{sup 7-8} M {sub ☉} at z ∼ 3 which might evolve into ∼10{sup 8.5-9} M {sub ☉} mass BHs at z = 0. Following our clustering measurements, we argue that this fast BH growth at z ∼ 3 in AGNs with moderate luminosity occurs in DMHs with typical mass of ∼ 6× 10{sup 12} h {sup –1} M {sub ☉}.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  20. The X-ray spectral properties of the AGN population in the XMM-Newton bright serendipitous survey

    NASA Astrophysics Data System (ADS)

    Corral, A.; Della Ceca, R.; Caccianiga, A.; Severgnini, P.; Brunner, H.; Carrera, F. J.; Page, M. J.; Schwope, A. D.

    2011-06-01

    Context. X-ray surveys are a key instrument in the study of active galactic nuclei (AGN). Thanks to their penetrating ability, X-rays are able to map the innermost regions close to the central super massive black hole (SMBH) as well as to detect and characterize its emission up to high redshift. Aims: We present here a detailed X-ray spectral analysis of the AGN belonging to the XMM-Newton bright survey (XBS). The XBS is composed of two flux-limited samples selected in the complementary 0.5-4.5 and 4.5-7.5 keV energy bands and comprising more than 300 AGN up to redshift ~2.4. Methods: We performed an X-ray analysis following two different approaches: by analyzing individually each AGN X-ray spectrum and by constructing average spectra for different AGN types. Results: From the individual analysis, we find that there seems to be an anti correlation between the spectral index and the sources' hard X-ray luminosity, such that the average photon index for the higher luminosity sources (>1044 erg s-1) is significantly (>2σ) flatter than the average for the lower luminosity sources. We also find that the intrinsic column density distribution agrees with AGN unified schemes, although a number of exceptions are found (3% of the whole sample), which are much more common among optically classified type 2 AGN. We also find that the so-called "soft-excess", apart from the intrinsic absorption, constitutes the principal deviation from a power-law shape in AGN X-ray spectra and it clearly displays different characteristics, and likely a different origin, for unabsorbed and absorbed AGN. Regarding the shape of the average spectra, we find that it is best reproduced by a combination of an unabsorbed (absorbed) power law, a narrow Fe Kα emission line and a small (large) amount of reflection for unabsorbed (absorbed) sources. We do not significantly detect any relativistic contribution to the line emission and we compute an upper limit for its equivalent width (EW) of 230 eV at

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  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. 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.

  4. 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.

  5. Discovering Rare AGN with Stripe 82X

    NASA Astrophysics Data System (ADS)

    LaMassa, S.; Urry, C.; Cappelluti, N.; Comastri, A.; Glikman, E.; Richards, G.; Boehringer, H.; Murray, S.; Civano, F.

    2014-07-01

    We have begun a wide-area survey overlapping the Sloan Digital Sky Survey (SDSS) region Stripe 82 which contains extensive multi-wavelength coverage from both ground- and space-based observatories. With the initial data release of Stripe 82X, covering 16.5 deg^{2} from XMM-Newton and Chandra, we identified ˜3300 X-ray sources, including the highest spectroscopically confirmed X-ray selected quasar to date (z = 5.86). I will review the science highlights of this survey so far, including the space density of high luminosity AGN and results from our ground-based campaign to target optically dull, infrared bright targets, which are prime candidates for obscured AGN at high redshift. I will conclude with a discussion of what we expect to learn with the additional 20 deg^{2} of coverage with XMM-Newton awarded to us in AO 13, which will more than double our current survey area.

  6. The universal spectrum of AGNs and QSOs

    NASA Technical Reports Server (NTRS)

    Kazanas, D.

    1985-01-01

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

  7. AGN feedback in galaxy clusters and groups

    NASA Astrophysics Data System (ADS)

    Hardcastle, Martin

    2016-07-01

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

  8. Jets in AGN at extremely high redshifts

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  9. AGN Black Hole Masses from Reverberation Mapping

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.

    2004-01-01

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

  10. Do stars contribute to AGN fuelling?

    NASA Astrophysics Data System (ADS)

    Davies, Richard

    2011-11-01

    While the existence of a starburst-AGN connection is undisputed, there is no consensus on whether AGN fuelling is synchronous with star formation or follows it during a post-starburst phase. I begin by presenting an overview of some of the observational evidence and theoretical models favouring each perspective. I then focus on recent high resolution observations that are able to probe the central tens of parsecs where star formation might influence AGN activity. I show that both the starburst phase and the physical state of the dense molecular gas imply that stellar feedback plays a critical role in first hindering and then helping accretion. I argue that it is only after the early turbulent phases of a starburst that gas from slow stellar winds can accrete efficiently to smaller scales. And I outline other contexts where similar processes appear to be at work. I finish by showing how the properties of the obscuring torus are directly coupled to this star formation, and that we should be thinking of the torus as a complex dynamical entity.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Merloni, A.; Bongiorno, A.

    2014-07-01

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

  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. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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

  3. A comparative study of AGN feedback algorithms

    NASA Astrophysics Data System (ADS)

    Wurster, J.; Thacker, R. J.

    2013-05-01

    Modelling active galactic nuclei (AGN) feedback in numerical simulations is both technically and theoretically challenging, with numerous approaches having been published in the literature. We present a study of five distinct approaches to modelling AGN feedback within gravitohydrodynamic simulations of major mergers of Milky Way-sized galaxies. To constrain differences to only be between AGN feedback models, all simulations start from the same initial conditions and use the same star formation algorithm. Most AGN feedback algorithms have five key aspects: the black hole accretion rate, energy feedback rate and method, particle accretion algorithm, black hole advection algorithm and black hole merger algorithm. All models follow different accretion histories, and in some cases, accretion rates differ by up to three orders of magnitude at any given time. We consider models with either thermal or kinetic feedback, with the associated energy deposited locally around the black hole. Each feedback algorithm modifies the region around the black hole to different extents, yielding gas densities and temperatures within r ˜ 200 pc that differ by up to six orders of magnitude at any given time. The particle accretion algorithms usually maintain good agreement between the total mass accreted by dot{M} dt and the total mass of gas particles removed from the simulation, although not all algorithms guarantee this to be true. The black hole advection algorithms dampen inappropriate dragging of the black holes by two-body interactions. Advecting the black hole a limited distance based upon local mass distributions has many desirably properties, such as avoiding large artificial jumps and allowing the possibility of the black hole remaining in a gas void. Lastly, two black holes instantly merge when given criteria are met, and we find a range of merger times for different criteria. This is important since the AGN feedback rate changes across the merger in a way that is dependent

  4. The AGN origin of cluster magnetic fields

    NASA Astrophysics Data System (ADS)

    Xu, Hao

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

  5. AGN Variability Surveys: DASCH from BATSS to EXIST

    NASA Astrophysics Data System (ADS)

    Grindlay, J. E.

    2007-10-01

    Active galactic nuclei (AGN) are variable on a wide range of timescales. Combined with their redshifts and thus luminosity, variability was of course instrumental in their initial identification with accretion onto supermassive black holes. Previous broad-band (both spectral and temporal) variability surveys of AGN are limited in their temporal and spectral bandwidth, despite their promise for probing the central engine and black hole mass. We provide a brief summary of three new AGN variability surveys, two (BATSS and DASCH) about to begin and the third (EXIST) possible within the next decade, which will open new windows on the physics and fundamental properties of AGN.

  6. Investigating The AGN Population In Cluster Environments Across Different Wavelengths

    NASA Astrophysics Data System (ADS)

    Byler, Eleanor; Norman, D.

    2011-01-01

    Currently, there is no complete picture of AGN formation and evolution in galaxy clusters. A general understanding of the AGN population has been impeded by cluster and selection biases and recent studies have shown that there is a large population of obscured or optically unremarkable AGN in galaxy clusters. We used SDSS data to look at the AGN distribution in 12 clusters over a range of redshifts (z = 0.16 - 0.35) and compared the optical and X-ray AGN content with that of six `blank’ fields. We found that on average the cluster fields had a small optical AGN excess as compared to blank fields. The AGN population and distribution was also compared by cluster morphology, and non-virialized clusters were found to have a higher X-ray and optical AGN content than virialized clusters. We also compare our optical AGN to Gilmour et al.'s (2009) X-ray survey to compare assumptions made about cluster membership. Byler 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.

  7. IGM Heating and AGN activity in Fossil Galaxy Groups

    NASA Astrophysics Data System (ADS)

    Miraghaei, H.; Khosroshahi, H. G.; Klöckner, H.-R.; Ponman, T. J.; Jetha, N. N.; Raychaudhury, S.

    2014-07-01

    Fossil galaxy groups are energetically and morphologically ideal environments to study the intergalactic medium (IGM) heating, because their inter-galactic gas is undisturbed due to the lack of recent group scale mergers. We study the role of active galactic nuclei (AGN) in heating the IGM in a sample of five fossil galaxy groups by employing properties at 610 MHz and 1.4 GHz. We find that two of the dominant galaxies in fossil groups, ESO 3060170 and RX J1416.4+2315, are associated with the radio lobes. We evaluate the PdV work of the radio lobes and their corresponding heating power and compare to the X-ray emission loss within cooling radius. Our results show that the power due to mechanical heating is not sufficiently high to suppress the cooling.

  8. HST-COS OBSERVATIONS OF AGNs. I. ULTRAVIOLET COMPOSITE SPECTRA OF THE IONIZING CONTINUUM AND EMISSION LINES

    SciTech Connect

    Shull, J. Michael; Stevans, Matthew; Danforth, Charles W. E-mail: matthew.stevans@colorado.edu

    2012-06-20

    The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting the emission-line spectra of AGNs and for photoionization and heating of the intergalactic medium. Using ultraviolet spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we have directly measured the rest-frame ionizing continua and emission lines for 22 AGNs. Over the redshift range 0.026 < z < 1.44, COS samples the Lyman continuum and many far-UV emission lines (Ly{alpha} {lambda}1216, C IV {lambda}1549, Si IV/O IV] {lambda}1400, N V {lambda}1240, O VI {lambda}1035). Strong EUV emission lines with 14-22 eV excitation energies (Ne VIII {lambda}{lambda}770, 780, Ne V {lambda}569, O II {lambda}834, O III {lambda}833, {lambda}702, O IV {lambda}788, 608, 554, O V {lambda}630, N III {lambda}685) suggest the presence of hot gas in the broad emission-line region. The rest-frame continuum, F{sub {nu}}{proportional_to}{nu}{sup {alpha}{sub {nu}}}, shows a break at wavelengths {lambda} < 1000 A, with spectral index {alpha}{sub {nu}} = -0.68 {+-} 0.14 in the FUV (1200-2000 A) steepening to {alpha}{sub {nu}} = -1.41 {+-} 0.21 in the EUV (500-1000 A). The COS EUV index is similar to that of radio-quiet AGNs in the 2002 HST/FOS survey ({alpha}{sub {nu}} = -1.57 {+-} 0.17). We see no Lyman edge ({tau}{sub HI} < 0.03) or He I {lambda}584 emission in the AGN composite. Our 22 AGNs exhibit a substantial range of FUV/EUV spectral indices and a correlation with AGN luminosity and redshift, likely due to observing below the 1000 A spectral break.

  9. Infrared and hard X-ray diagnostics of AGN identifications from the Swift/BAT and AKARI all sky surveys.

    NASA Astrophysics Data System (ADS)

    Matsuta, Keiko

    2011-11-01

    It is known that there is a good correlation between the mid-infrared and the intrinsic soft X-ray luminosities (<10 keV) of local active galactic nuclei (AGN). We now combine two complete all sky surveys in order to study the connection between the infrared and very hard X-ray (>10 keV) luminosities in AGN. We selected sources from the 22-month Swift/BAT hard X-ray survey catalogue which were also detected by Infrared Camera (IRC, 9 and 18 micron) and Far-Infrared Surveyor (FIS, 90 micron) on AKARI. The large sample allows us to include not only Seyfert 1 and 2 galaxies but also quasars, low luminosity AGN and radio-loud objects. We found a strong linear correlation for most of the AGN between the logarithms of the observed infrared and hard X-ray powers over four decades in luminosity, L(IR) vs. L(HX). Many Compton-thick sources show a large deviation from the correlation, probably because of the relatively low observed L(HX) due to the high column density. The observed luminosity correlation indicates that the various types of AGN may be occupying distinct regions of parameter space in the diagram. Color-color plots such as "L(90um)/L(9um) vs. L(HX)/L(9um)" are found to be useful redshift independent indicators for isolating Compton-thick AGN. Interestingly, starburst galaxies are also separated in this plane. This correlation can be a new and important tool for AGN classification, which may be useful for large upcoming surveys.

  10. 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.

  11. Galaxies, AGN, and Environment at z=1: IRAC observations of DEEP2

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Hickox, Ryan; Bundy, Kevin; Coil, Alison; Cool, Richard; Cooper, Michael; Croton, Darren; Davis, Marc; Eisenhardt, Peter; Eisenstein, Daniel; Faber, Sandy; Forman, William; Koo, David; Murray, Stephen; Papovich, Casey; Stern, Daniel; Weiner, Benjamin; Willmer, Christopher; Willner, Steven

    2008-03-01

    The Spitzer view of the z=1 Universe is spectroscopy starved. Only 5 sq. deg. of the sky have been surveyed with very deep (24th mag) spectroscopy that probes z>1 galaxies, and only about half of this area has been observed with Spitzer. Cosmic variance is severe even at z>1 and limits our ability to measure the evolution of galaxies and AGN at these epochs. DEEP2 is the premier z>1 wide-field survey, but only 1.5 sq. deg. of it has Spitzer coverage. Here we propose to more than double the overlap between Spitzer and DEEP2, with IRAC coverage of two fields that contain ~16,000 high-quality Keck spectra of galaxies at 0.7AGN, across a wide range of environments, as a function of redshift. IRAC data will provide robust stellar masses (especially for blue galaxies) and allow us to identify at least 50% more AGN than are found in the X-ray and optical bands alone, revealing a unbiased view of the AGN population to high levels of obscuration. We will use the dense DEEP2 sampling to determine small-scale environments and clustering of galaxies and AGN as a function of stellar mass, color and luminosity. We will also be able to compare IRAC-based stellar masses with DEEP2 dynamical masses. The proposed observations will increase the overlap between IRAC and DEEP2 by a factor of 2.3. This will greatly increase the statistical power of the survey, reduce cosmic variance, and allow measurements of environment and clustering in multiple bins of AGN luminosity or stellar mass, needed to constrain galaxy and AGN evolution models. DEEP2 is the only survey that provides high-quality galaxy spectra and precise redshifts over a large volume at high redshift; these observations will therefore produce a lasting legacy dataset for

  12. The X-ray flux dipole of AGNs as an indicator of the local gravitational field

    NASA Technical Reports Server (NTRS)

    Miyaji, Takamitsu; Jahoda, Keith; Boldt, Elihu

    1991-01-01

    We have investigated the dipole anisotropy of the sky X-ray flux from nearby AGNs to compare with the peculiar motion of the Local Group (LG) using a more extensive sample than that of Miyaji and Boldt (1990). We have sampled 56 low redshift emission-line AGNs (z less than 0.06) from the HEAO 1 A-2 experiment with a flux limit lower than that of Piccinotti et al. (1982) and with a lower galactic latitude cutoff. Our sample shows a significant dipole anisotropy whose apex is only about 30 deg away from the direction of the Local Group's peculiar motion for the objects with z less than 0.015. The dipole growth vs. redshift shows a sharp rise between z = 0.006 and z = 0.015; the amplitude of the dipole is 40 +/- 10 percent of the corresponding monopole at z = 0.015. The outer redshift cutoff is consistent with the results obtained from analyses using optical and IRAS galaxies. The present sample strengthens our previous conclusion that X-ray emission from AGNs traces the underlying mass distribution as strongly as optical and IR emission from galaxies.

  13. VizieR Online Data Catalog: BLR-less AGNs in Stripe82 (Zhang, 2014)

    NASA Astrophysics Data System (ADS)

    Zhang, X.-G.

    2014-11-01

    In order to select the reliable candidates for the BLR-less AGNs through both the photometry variabilities and the observed spectral features, we apply the following procedures to the objects in the SDSS Stripe82 Database. The emission line parameters should be first determined, in order to confirm that our spectroscopic sample includes the pure narrow line objects only (type 2 objects, the objects having both strong and weak broad lines cannot be considered). Then, the SDSS photometric light curves of the objects in the spectroscopic sample should be carefully analysed to find the reliable candidates for the BLR-less AGNs. We use data from http://www.sdss3.org/dr8/spectro/spectro_access.php (1 data file).

  14. 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.

  15. Long-term Variation of AGNs

    NASA Astrophysics Data System (ADS)

    Fan, J. H.; Xie, G. Z.; Adam, G.; Copin, Y.; Lin, R. G.; Bai, J. M.; Quin, Y. P.

    In this paper we will present the long-term variation in the optical and the infrared bands for some selected AGNs. 1. Some new optical data observed by us have been presented for BL Lacertae (1995-1996) and OJ 287 (1994-1995), and new infrared data are presented for OJ 287 (Nov=2E 1995), which corresponds to the second optical peak (Sillanpaa et al. 1996; Takalo et al. 1996) and during last outburst. 2. For objects with long term observations, the Jurkevich's method has been used to analyses the long-term variation period. It is interesting that the reported periods of AGNs are of the similar value of about 10 years: 3C 345 11.4 years (Webb et al. 1988), 3C 120 15 years (Belokon et al. 1987; Hagen-Thorn et al. 1997), ON 231 13.6 years (Liu et al. 1995), OJ 287 12 years (Sillanpaa et al. 1988; Kidger et al. 1992), PKS 0735+178 14 years (Fan et al. 1997), NGC 4151 15 years (Fan et al. 1998a), BL Lacertae 14.0 years (Fan et al. 1998b). Is the mechanism for the long-term variation the same for different AGNs? 3. The DCF method has been adopted to analysis the variation correlation in the optical and infrared bands for BL Lac object OJ 287, the results show that these two bands are strongly correlated, which suggest that the emission mechanism in the two bands is the same. 4. For the optical and infrared bands, the maximum variations are correlated.

  16. A search for relativistic outflows signatures in the X-ray spectra of radio-quiet AGNs

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Yaqoob, T.; Braito, V.; Dadina, M.

    2010-07-01

    We performed a blind search for blue-shifted Fe K absorption lines at energies greater than 6 keV in the X-ray spectra of a sample of 44 radio-quiet AGNs observed with XMM-Newton. We statistically quantified the parameters and the incidence of such lines and also determined their detection significance through extensive Monte Carlo simulations. This allows us to define their global veracity and to overcome the reported publication bias. These findings suggest the presence of previously unknown ultra-fast outflows in radio-quiet AGNs.

  17. 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

  18. AGN disks and black holes on the weighting scales

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  19. X-ray variability in AGN: LINER vs. Seyfert 2

    NASA Astrophysics Data System (ADS)

    Hernandez-Garcia, Lorena; Masegosa, Josefa; Gonzalez-Martin, Omaira; Marquez, Isabel

    2015-09-01

    Although variability is a general property characterizing active galactic nuclei (AGN), it is not well stablished if 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 low luminosity AGN in a large sample, including 18 low ionization nuclear emission line regions (LINERs) and 26 type 2 Seyferts (Sy2), 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, whereas 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. Short term variations are not found at X-rays, but variations in timescales of months/years is very common in both families. The main driver of the long term X-ray variations seems to be related to changes in the nuclear power in both LINERs and Sy2, but other variability patterns cannot be discarded in a few cases, because changes of the column density or at soft energies are also found. The X-ray variations occur in the same way in LINERs and type 2 Seyferts, i.e., related to the nuclear continuum, but they might have different accretion mechanisms. As absorption variations and changing-look sources are not observed in LINERs, but UV nuclear variations are common, we speculate that the BLR and the torus might disappear in these sources.

  20. The AGN Content of the Micron all Sky Survey

    NASA Technical Reports Server (NTRS)

    Cutri, R. M.

    2000-01-01

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

  1. 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.

  2. 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.

  3. 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.

  4. Faint COSMOS AGNs at z∼3.3. I. Black Hole Properties and Constraints on Early Black Hole Growth

    NASA Astrophysics Data System (ADS)

    Trakhtenbrot, B.; Civano, F.; Urry, C. Megan; Schawinski, K.; Marchesi, S.; Elvis, M.; Rosario, D. J.; Suh, H.; Mejia-Restrepo, J. E.; Simmons, B. D.; Faisst, A. L.; Onodera, M.

    2016-07-01

    We present new Keck/MOSFIRE K-band spectroscopy for a sample of 14 faint, X-ray-selected active galactic nuclei (AGNs) in the COSMOS field. The data cover the spectral region surrounding the broad Balmer emission lines, which enables the estimation of black hole masses ({M}{BH}) and accretion rates (in terms of L/{L}{Edd}). We focus on 10 AGNs at z ≃ 3.3, where we observe the Hβ spectral region, while for the other four z ≃ 2.4 sources we use the {{H}}α broad emission line. Compared with previous detailed studies of unobscured AGNs at these high redshifts, our sources are fainter by an order of magnitude, corresponding to number densities of order ∼10‑6–10‑5 {{Mpc}}-3. The lower AGN luminosities also allow for a robust identification of the host galaxy emission, necessary to obtain reliable intrinsic AGN luminosities, BH masses and accretion rates. We find the AGNs in our sample to be powered by supermassive black holes (SMBHs) with a typical mass of {M}{BH}≃ 5× {10}8 {M}ȯ —significantly lower than the higher-luminosity, rarer quasars reported in earlier studies. The accretion rates are in the range L/{L}{Edd} ∼ 0.1–0.4, with an evident lack of sources with lower L/{L}{Edd} (and higher {M}{BH}), as found in several studies of faint AGNs at intermediate redshifts. Based on the early growth expected for the SMBHs in our sample, we argue that a significant population of faint z ∼ 5‑6 AGNs, with {M}{BH}∼ {10}6 {M}ȯ , should be detectable in the deepest X-ray surveys available, but this is not observed. We discuss several possible explanations for the apparent absence of such a population, concluding that the most probable scenario involves an evolution in source obscuration and/or radiative efficiencies.

  5. 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.

  6. Early Results from Swift AGN and Cluster Survey

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

    McGinnis, Daniel J.

    2013-12-01

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

  8. Long Term Profile Variability of Double-Peaked Emission Lines in AGNs

    NASA Astrophysics Data System (ADS)

    Lewis, K.; Eracleous, M.; Halpern, J.; Storchi-Bergmann, T.

    2004-06-01

    An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines, which are thought to arise from the outer regions of the accretion disk which fuels the AGN. The line profiles are observed to vary on a characteristic timescales of 5-10 years. The variability is not a reverberation effect; it is a manifestation of physical changes in the disk. Our group has monitored a set of 20 double-peaked emitters for the past 8 years (longer for some objects). Here, we characterize the variability of the double-peaked Hα line profiles in five objects from our sample. By experimenting with simple models, we find that disks with a single precessing spiral arm are able to reproduce many of the variability trends that are seen in the data.

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

  10. 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.

  11. 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.

  12. Structure Function Analysis of AGN Variability using Kepler

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  13. Compton Thick AGN in the XMM-COSMOS field

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  14. Mid-infrared diagnostics to distinguish AGNs from starbursts

    NASA Astrophysics Data System (ADS)

    Laurent, O.; Mirabel, I. F.; Charmandaris, V.; Gallais, P.; Madden, S. C.; Sauvage, M.; Vigroux, L.; Cesarsky, C.

    2000-07-01

    We present new mid-infrared (MIR) diagnostics to distinguish emission of active galactic nuclei (AGN) from that originating in starburst regions. Our method uses empirical spectroscopic criteria based on the fact that MIR emission from star forming or active galaxies arises mostly from HII regions, photo-dissociation regions (PDRs) and AGNs. The analysis of the strength of the 6.2 mu m Unidentified Infrared Band (UIB) and the MIR continuum shows that UIBs are very faint or absent in regions harboring the intense and hard radiation fields of AGNs and pure HII regions, where the UIB carriers could be destroyed. The MIR signature of AGNs is the presence of an important continuum in the 3-10 mu m band which originates from very hot dust heated by the intense AGN radiation field. Using these two distinct spectral properties found in our MIR templates, we build diagnostic diagrams which provide quantitative estimates of the AGN, PDR and HII region contribution in a given MIR spectrum. This new MIR classification can be used to reveal the presence of AGNs highly obscured by large columns of dust. Based on observations made with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

  15. Compton Thick AGN in the XMM-COSMOS field

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  16. 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.

  17. 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.

  18. Absorption-line measurements of AGN outflows

    NASA Astrophysics Data System (ADS)

    Fields, Dale L.

    Investigations into the elemental abundances in two nearby active galaxies, the narrow-line Seyfert 1 Markarian 1044 and the Seyfert 1 Markarian 279, are reported. Spectra from three space-based observatories HST, FUSE, and CHANDRA, are used to measure absorption lines in material outflowing from the nucleus. I make multi-wavelength comparisons to better convert the ionic column densities into elemental column densities which can then be used to determine abundances (metallicities). Narrow-line Seyfert 1 galaxies are known to have extreme values of a number of properties compared to active galactic nuclei (AGNs) as a class. In particular, emission-line studies have suggested that NLS1s are unusually metal-rich compared to broad-line AGNs of comparable luminosity. To test these suggestions I perform absorption-line studies on the NLS1 Markarian 1044, a nearby and bright AGN. I use lines of H I, C IV, N V, and O VI to properly make the photoionization correction through the software Cloudy and determine abundances of Carbon, Nitrogen and Oxygen. I find two results. The first is that Markarian 1044 has a bulk metallicity greater than five times solar. The second is that the N/C ratio in Markarian 1044 is consistent with a solar mixture. This is in direct contradiction of extrapolations from local H II regions which state N/ C should scale with bulk metallicity. This implies a different enrichment history in Markarian 1044 than in the Galactic disk. I also report discovery of three new low-redshift Lya forest lines with log N HI >= 12:77 in the spectrum of Markarian 1044. This number is consistent with the 2.6 expected Lya forest lines in the path length to Markarian 1044. I also investigate the CHANDRA X-ray spectrum of Markarian 279, a broad-line Seyfert 1. I use a new code, PHASE, to self-consistently model the entire absorption spectrum simultaneously. Using solely the X-ray spectrum I am able to determine the physical parameters of this absorber to a degree only

  19. Supernovae and AGN Driven Galactic Outflows

    NASA Astrophysics Data System (ADS)

    Sharma, Mahavir; Nath, Biman B.

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Tadhunter, Clive

    2016-06-01

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

  1. The Spitzer Mid-infrared AGN Survey. II. The Demographics and Cosmic Evolution of the AGN Population

    NASA Astrophysics Data System (ADS)

    Lacy, M.; Ridgway, S. E.; Sajina, A.; Petric, A. O.; Gates, E. L.; Urrutia, T.; Storrie-Lombardi, L. J.

    2015-04-01

    We present luminosity functions derived from a spectroscopic survey of active galactic nuclei (AGNs) selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of obscured and unobscured AGNs in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts (z\\gt 1.6), we find significantly more AGNs at a given bolometric luminosity than found by either optical quasar surveys or hard X-ray surveys. The fraction of obscured AGNs decreases rapidly with increasing AGN luminosity, but, at least at high redshifts, appears to remain at ≈ 50% even at bolometric luminosities ˜ {{10}14} {{L}⊙ }. The data support a picture in which the obscured and unobscured populations evolve differently, with some evidence that high luminosity obscured quasars peak in space density at a higher redshift than their unobscured counterparts. The amount of accretion energy in the universe estimated from this work suggests that AGNs contribute about 12% to the total radiation intensity of the universe, and a high radiative accretion efficiency ≈ 0.18-0.07+0.12 is required to match current estimates of the local mass density in black holes.

  2. Role of reconnection in AGN jets

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2003-10-01

    We discuss the possible role of reconnection in electro-magnetically dominated cores of relativistic AGN jets. We suggest that reconnection may proceed in a two-fold fashion: initial explosive collapse on the Alfvén time-scale of a current-carrying jet (which is of the order of the light crossing time) and subsequent slow quasi-steady reconnection. Sites of explosive collapse are associated with bright knots, while steady-state reconnection re-energizes particles in the 'bridges' between the knots. Ohmic dissipation in reconnection layers leads to particle acceleration either by inductive electric fields or by stochastic particle acceleration in the ensuing electro-magnetic turbulence.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  4. The Stripe 82X Multiwavelength Survey of Supermassive Black Hole Growth in Powerful AGN

    NASA Astrophysics Data System (ADS)

    Urry, C. Megan; LaMassa, Stephanie M.; Cappelluti, Nico; Ananna, Tonima; Salvato, Mara; Civano, Francesca; Marchesi, Stefano; Comastri, Andrea; Richards, Gordon T.; Glikman, Eilat; Boehringer, Hans; Brusa, Marcella; Cardamone, Carolin; Chon, Gayoung; Farrah, Duncan; Gilfanov, Marat; Green, Paul J.; Komossa, Stefanie; Lira, Paulina; Makler, Martin; Pecoraro, Robert; Ranalli, Piero; Schawinski, Kevin; Stern, Daniel K.; Treister, Ezequiel; Viero, Marco; Stripe 82X Collaboration

    2016-01-01

    Deep multiwavelength surveys over the past 15 years have told us that most black hole growth in low- to moderate-luminosity AGN is obscured, and thus not well sampled by optical or soft X-ray surveys. To study whether this also holds for high-luminosity AGN, however, requires a large volume survey (because luminous AGN are rare) that is sensitive to hard X-ray plus infrared emission out to high redshifts. Stripe 82X is exactly this survey — it adds X-ray coverage at F(0.5-10 keV) ≥ 10-15 ergs/cm^2/s to an equatorial legacy field with abundant data at other wavelengths, including far- and mid-infrared imaging (Herschel, Spitzer, WISE, UKIDSS, VHS, VICS82), deep radio imaging (VLA), deep optical imaging (SDSS, HSC, DES, CFHT), UV imaging (GALEX medium-depth), and extensive optical spectroscopy (~800 spectra per square degree). The current 31.3 deg2 X-ray catalog has 6181 unique X-ray sources, of which 88% have optical or infrared counterparts and 1842 have spectroscopic redshifts. We present the characteristics of this source population and describe our search for high-luminosity and/or high-redshift obscured quasars.

  5. 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 .

  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. 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.

  9. 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.

  10. The KMOS AGN Survey at High Redshift (KASHz)

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The KMOS AGN Survey at High Redshift (KASHz) is an extensive observational programme to obtain spatially resolved spectroscopy of distant galaxies that host rapidly growing supermassive black holes (i.e., active galactic nuclei [AGN]). By exploiting the unique capabilities of KMOS we will spatially resolve the ionised gas kinematics in around 200 such galaxies. A fundamental prediction of galaxy formation models is that AGN inject considerable energy into their host galaxies and ultimately destroy or remove star-forming material via outflows. However, until now, observational constraints of this prediction have been limited to only a small number of distant galaxies. KASHz will provide the strongest constraints to date on the prevalence, properties and impact of ionised outflows in the host galaxies of distant AGN. The survey is described and our first results presented.

  11. The merging/AGN connection. II. Ionization of the circumnuclear regions

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Becker, T.; Garcia-Lorenzo, B.; Benn, C. R.; Christensen, L.; Kelz, A.; Jahnke, K.; Roth, M. M.

    2005-01-01

    We report the first results of a study of a sample of 20 galaxy mergers/interacting systems, using the VIMOS and PMAS integral field spectrographs. For each object, we extracted the integrated spectrum of the central regions and analyzed the ionization state using classical diagnostic diagrams \\citep{veil87}. There is evidence of AGN ionization in 4 of the objects, i.e. 20% of the sample, a considerably higher fraction than found in previous studies (˜4%). An increase of the nuclear activity with the far infrared temperature may account for the difference.

  12. 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.

  13. 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.

  14. A Herschel View on Galaxy/AGN Co-Evolution

    NASA Astrophysics Data System (ADS)

    Lutz, D.; Pep Consortium

    2011-10-01

    Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. The PACS Evolutionary Probe (PEP) guaranteed time key program obtains deep photometric surveys of some of the key extragalactic multiwavelength fields at wavelengths between 70 and 160μm. This contribution gives an overview of first science results, illustrating the potential of Herschel in providing calorimetric star formation rates for various high redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies. Herschel measured star formation rates of high redshift X-ray AGN suggest an interplay between two paths of AGN/host coevolution. A correlation of AGN luminosity and host star formation is traced locally over a wide range of luminosities and also extends to luminous high-z AGN. This correlation reflects an evolutionary connection, likely via merging. For lower AGN luminosities, star formation is similar to that in non-active massive galaxies and shows little dependence on AGN luminosity. The level of this secular, non-merger driven star formation increasingly dominates over the correlation at increasing redshift.

  15. Modeling IR SED of AGN with Spitzer and Herschel data

    NASA Astrophysics Data System (ADS)

    Feltre, A.

    2012-12-01

    One of the remaining open issues in the context of the analysis of Active Galactic Nuclei (AGN) is the evidence that nuclear gravitational accretion is often accompanied by a concurrent starburst (SB) activity. What is, in this picture, the role played by the obscur- ing dust around the nucleus and what do the state of the art AGN torus models have to say? Can the IR data provided by Spitzer and Herschel help us in extensively investigate both phenomena and, if so, how and with what limitations? In this paper we present our contribution to the efforts of answering these questions. We show some of the main results coming from a comparative study of various AGN SED modeling approaches, focusing mostly on the much-debated issue about the morphology of the dust distribution in the toroidal structure surrounding the AGN. We found that the properties of dust in AGN as measured by matching observations (be it broad band IR photometry or IR spectra) with models, strongly depend on the choice of the dust distribution. Then, we present the spec- tral energy distribution (SED) fitting procedure we developed, making make the best use of Spitzer and Herschel SPIRE mid- and far-IR observations, to dig into the role played by the possible presence of an AGN on the host galaxy's properties.

  16. 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.

  17. On the physical origin of AGN outflow driving mechanisms

    NASA Astrophysics Data System (ADS)

    Ishibashi, Wako

    2016-07-01

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

  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. Star Formation Black Hole Growth and Dusty Tori in the Most Luminous AGNs at z=2-3.5

    NASA Astrophysics Data System (ADS)

    Netzer, Hagai; Lani, Caterina; Nordon, Raanan; Trakhtenbrot, Benny; Lira, Paulina; Shemmer, Ohad

    2016-03-01

    We report Herschel/SPIRE observations of 100 very luminous, optically selected active galactic nuclei (AGNs) at z=2{--}3.5 with {log} {L}{{1350}} (erg s-1) ≥ 46.5 , where {L}{{1350}} is λLλ at 1350 Å. The distribution in {L}{{1350}} is similar to the general distribution of Sloan Digital Sky Survey AGNs in this redshift and luminosity interval. We measured star-formation (SF) luminosity, {L}{{SF}}, and SF rate (SFR) in 34 detected sources by fitting combined SF and torus templates, where the torus emission is based on Wide Field Infrared Survey Explorer observations. We also obtained statistically significant stacks for the undetected sources in two luminosity groups. The sample properties are compared with those of very luminous AGNs at z\\gt 4.5. The main findings are: (1) The mean and the median SFRs of the detected sources are {1176}-339+476 and {1010}-503+706 M⊙ yr-1, respectively. The mean SFR of the undetected sources is 148 M⊙ yr-1. The ratio of SFR to the black hole accretion rate is ≈80 for the detected sources and less than 10 for the undetected sources. Unlike a sample of sources at z ≃ 4.8 that we studied recently, there is no difference in {L}{{AGN}} and only a very small difference in {L}{{torus}} between the detected and undetected sources. (2) The redshift distribution of {L}{{SF}} and {L}{{AGN}} for the most luminous, redshift 2-7 AGNs are different. Similar to previous studies, the highest {L}{{AGN}} are found at z ≈ 3. However, the {L}{{SF}} of such sources peaks at z ≈ 5. Assuming the objects in our sample are hosted by the most massive galaxies at those redshifts, we find that approximately 2/3 of the hosts are already below the main sequence of SF galaxies at z = 2-3.5. (3) The spectral energy distributions (SEDs) of dusty tori at high redshift are similar to the shapes found in low redshift, low luminosity AGNs. Herschel upper limits put strong constraints on the long wavelength shape of the SED, ruling out several earlier

  20. The complete census of optically selected AGNs in the Coma supercluster: the dependence of AGN activity on the local environment

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Savorgnan, G.; Fumagalli, Mattia

    2011-10-01

    Aims: To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma supercluster whose density spans two orders of magnitude from the sparse filaments to the cores of rich clusters. Methods: We obtained optical spectra of the nuclei of 283 galaxies using the 1.5 m Cassini telescope of Bologna observatory. Among these galaxies, 177 belong to the Coma supercluster and are added to the 4785 spectra available from SDSS (DR7) to fill-in the incomplete coverage by SDSS of luminous galaxies. We perform a spectral classification of the nuclei of galaxies in this region (with a completeness of 98% at r ≤ 17.77), classifying the nuclear spectra in six classes: three of them (SEY, sAGN, LIN) refer to AGNs and the remaining three (HII, RET, PAS) refer to different stages of starburst activity. We perform this classification as recommended by Cid Fernandes and collaborators using the ratio of λ 6584 [NII] to Hα lines and the equivalent width of Hα (WHAN diagnostic), after correcting the last quantity by 1.3 Å for underlying absorption. Results: We find that 482 (10%) of 5027 galaxies host an AGN: their frequency strongly increases with increasing luminosity of the parent galaxies, such that 32% of galaxies with Log(Li/L⊙) ≥ 10.2 harbor an AGN at their interior. In addition to their presence in luminous galaxies, AGNs are also found in red galaxies with ⟨g - i⟩ ≃ 1.15 ± 0.15 mag. The majority of SEY and sAGN (strong AGNs) are associated with luminous late-type (or S0a) galaxies, while LIN (weak AGNs) and RET ("retired": nuclei that have experienced a starburst phase in the past and are now ionized by their hot evolved low-mass stars), are mostly found among E/S0as. The number density of AGNs, HII region-like, and retired galaxies is found to anti-correlate with the local density of galaxies, such that their frequency drops by a factor of two near the cluster

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  4. The radio-loud AGN population at z ≳ 1 in the COSMOS field. I. selection and spectral energy distributions

    NASA Astrophysics Data System (ADS)

    Baldi, Ranieri D.; Capetti, Alessandro; Chiaberge, Marco; Celotti, Annalisa

    2014-07-01

    We select a sample of radio galaxies at high redshifts (z ≳ 1) in the COSMOS field by cross-matching optical and infrared (IR) images with the FIRST radio data. The aim of this study is to explore the high-z radio-loud (RL) active galactic nuclei (AGN) population at much lower luminosities than the classical samples of distant radio sources, which are similar to those of the local population of radio galaxies. Precisely, we extended a previous analysis focused on low-luminosity radio galaxies. The wide multiwavelength coverage provided by the COSMOS survey allows us to derive their spectral energy distributions (SEDs). We model them with our own developed technique 2SPD that includes old and young stellar populations and dust emission. When added to those previously selected, we obtain a sample of 74 RL AGN. The SED modeling returns several important quantities associated with the AGN and host properties. The resulting photometric redshifts range from z ~ 0.7 to 3. The sample mostly includes compact radio sources but also 21 FR IIs sources; the radio power distribution of the sample covers ~1031.5 - 1034.3 erg s-1 Hz-1, thus straddling the local FR I/FR II break. The inferred range of stellar mass of the hosts is ~1010 - 1011.5M⊙. The SEDs are dominated by the contribution from an old stellar population with an age of ~1 - 3 Gyr for most of the sources. However, UV and mid-IR (MIR) excesses are observed for half of the sample. The dust luminosities inferred from the MIR excesses are in the range, Ldust ~ 1043 - 1045.5 erg s-1, which are associated with temperatures approximately of 350-1200 K. Estimates of the UV component yield values of ~1041.5 - 1045.5 erg s-1 at 2000 Å. The UV emission is significantly correlated with both IR and radio luminosities; the former being the stronger link. However, the origin of UV and dust emission, whether it is produced by the AGN of by star formation, is still unclear. Our results show that this RL AGN population at high

  5. 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.

  6. Galaxy-Scale Clouds of Ionized Gas around AGN

    NASA Astrophysics Data System (ADS)

    Chojnowski, S. Drew; Keel, William C.

    2012-02-01

    The serendipitous 2007 discovery of the object now known (even by NED) as "Hanny's Voorwerp" (Lintott et al. 2009) set into motion a search for more examples of galaxy-scale clouds of highly-ionized gas in the vicinity of active galactic nuclei (AGN). Using a sample assembled primarily by 'citizen scientists' via a dedicated thread in the Galaxy Zoo Forum, we carried out the first part of a larger long- slit spectroscopic survey of such objects with the 2.1m telescope at Kitt Peak National Observatory (KPNO). Of the 30 objects targeted during seven nights (multiple exposures for several), extended emission clouds were observed in 15 objects, with [OIII]λ5007 emission occasionally extending >30 kpc from galaxy cores. A strong majority (11/15) of the extended emission clouds coincide with merging or otherwise violently disrupted systems, but more relevant to our search were the handful of clouds coinciding with isolated, symmetric galaxies lacking an obvious excitation mechanism. We present the results of part one in the hunt for Voorwerp analogues, much of which served to weed-out the more interesting objects to be targeted for future, multi-wavelength studies.

  7. The power output of local obscured and unobscured AGN: crossing the absorption barrier with Swift/BAT and IRAS

    NASA Astrophysics Data System (ADS)

    Vasudevan, R. V.; Fabian, A. C.; Gandhi, P.; Winter, L. M.; Mushotzky, R. F.

    2010-02-01

    The Swift/Burst Alert Telescope (BAT) 9-month catalogue of active galactic nuclei (AGN) provides an unbiased census of local supermassive black hole accretion, and probes to all but the highest levels of absorption in AGN. We explore a method for characterizing the bolometric output of both obscured and unobscured AGN by combining the hard X-ray data from the Swift/BAT instrument (14-195keV) with the reprocessed infrared (IR) emission as seen with the Infrared Astronomical Satellite (IRAS) all-sky surveys. This approach bypasses the complex modifications to the spectral energy distribution introduced by absorption in the optical, UV and 0.1-10 keV regimes and provides a long-term, average picture of the bolometric output of these sources. We broadly follow the approach of Pozzi et al. for calculating the bolometric luminosities by adding nuclear IR and hard X-ray luminosities, and consider different approaches for removing non-nuclear contamination in the large-aperture IRAS fluxes. Using mass estimates from the black hole mass-host galaxy bulge luminosity relation, we present the Eddington ratios λEdd and 2-10 keV bolometric corrections for a subsample of 63 AGN (35 obscured and 28 unobscured) from the Swift/BAT catalogue, and confirm previous indications of a low Eddington ratio distribution for both samples. Importantly, we find a tendency for low bolometric corrections (typically 10-30) for the obscured AGN in the sample (with a possible rise from ~15 for λEdd < 0.03 to ~32 above this), providing a hitherto unseen window on to accretion processes in this class of AGN. This finding is of key importance in calculating the expected local black hole mass density from the X-ray background since it is composed of emission from a significant population of such obscured AGN. Analogous studies with high-resolution IR data and a range of alternative models for the torus emission will form useful future extensions to this work.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. 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.

  10. Oblique Shocks in AGN Jet Flows

    NASA Astrophysics Data System (ADS)

    Aller, H. D.; Aller, M. F.; Hughes, P. A.; Wardle, J. F. C.; Roberts, D. H.; Homan, D. C.

    2001-12-01

    We present multi-epoch VLBI images and single antenna monitoring results from a study of 10 highly variable AGNs (BL Lacs and QSOs) whose primary goal is to investigate the strengths and orientations of oblique shocks in relativistic flows by comparing observed polarized features found in VLBA total intensity and polarization images and UMRAO monitoring data with the predictions of simple oblique shock models which account for the effects of relativistic aberration. The data consist of weekly observations at 14.5, 8.0 and 4.8 GHz using the UMRAO 26-meter telescope, and seven sets of VLBA total flux and polarization images spaced over the past two years at 15 and 43 GHz supplemented by maps at 8 and 22 GHz for a subset known to exhibit significant opacity. The morphological evolution in both structure and polarization revealed by these data are used to provide an estimation of the projected flow deviation and magnetic field orientation at shocks, and initial results from a comparison of the data with newly developed radiative transfer models allowing for a range of shock orientations are presented. This work was supported in part by NSF grant AST-9900723. The UMRAO is supported by the University of Michigan; The National Radio Astronomy Observatory is operated by Associated Universities, Inc, under cooperative agreement with the National Science Foundation.

  11. Radio-Loud AGN: The Suzaku View

    NASA Technical Reports Server (NTRS)

    Sambruna, Rita

    2009-01-01

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

  12. From star-forming galaxies to AGN: the global HI content from a stacking experiment

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Morganti, R.; Oosterloo, T. A.; Hoppmann, L.; Staveley-Smith, L.

    2015-08-01

    We study the atomic neutral hydrogen (H I) content of ~1600 galaxies up to z ~ 0.1 using stacking techniques. The observations were carried out with the Westerbork Synthesis Radio Telescope (WSRT) in the area of the SDSS South Galactic Cap (SSGC), where we selected a galaxy sample from the SDSS spectroscopic catalog. Multi-wavelength information is provided by SDSS, NVSS, GALEX, and WISE. We use the collected information to study H I trends with color, star-forming, and active galactic nuclei (AGN) properties. Using near-UV (NUV) -r colors, galaxies are divided into blue cloud, green valley and red sequence galaxies. As expected based on previous observations, we detect H I in green valley objects with lower amounts of H I than blue galaxies, while stacking only produces a 3σ upper limit for red galaxies with MHI< (5 ± 1.5) × 108 M⊙ and MHI/Lr< 0.02 ± 0.006 M⊙/L⊙ (averaged over four redshift bins up to z ~ 0.1). We find that the H I content is more dependent on NUV -r color, and less on ionization properties, in the sense that regardless of the presence of an optical AGN (based on optical ionization line diagnostics), green-valley galaxies always show H I, whereas red galaxies only produce an upper limit. This suggests that feedback from optical AGN is not the (main) reason for depleting large-scale gas reservoirs. Low-level radio continuum emission in our galaxies can stem either from star formation, or from AGN. We use the WISE color-color plot to separate these phenomena by dividing the sample into IR late-type and IR early-type galaxies. We find that the radio emission in IR late-type galaxies stems from enhanced star formation, and this group is detected in H I. However, IR early-type galaxies lack any sign of H I gas and star formation activity, suggesting that radio AGN are likely to be the source of radio emission in this population. Future H I surveys will allow for extending our studies to higher redshift, and for testing any possible evolution

  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. The impact of AGN on their host galaxies

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.

    2014-07-01

    In these proceedings I briefly: (1) review the impact (or ``feedback'') that active galactic nuclei (AGN) are predicted to have on their host galaxies and larger scale environment, (2) review the observational evidence for or against these predictions and (3) present new results on ionised outflows in AGN. The observational support for the ``maintenance mode'' of feedback is strong (caveat the details); AGN at the centre of massive halos appear to be regulating the cooling of hot gas, which could in turn control the levels of future star formation (SF) and black hole growth. In contrast, direct observational support for more rapid forms of feedback, which dramatically impact on SF (i.e., the ``quasar mode''), remains elusive. From a systematic study of the spectra of ~24 000 AGN we find that extreme ionised gas kinematics are common, and are most prevalent in radio bright AGN (L 1.4 GHz > 103 W Hz-1). Follow-up IFU observations have shown that these extreme gas kinematics are extended over kilo-parsec scales. However, the co-existence of high-levels of SF, luminous AGN activity and radio jets raises interesting questions on the primary drivers and impact of these outflows. Galaxy-wide, high-mass outflows are being observed in an increasing number of AGN and are a plausible mechanism for the depletion of gas; however, there is still much work to be done to determine the physical processes that drive these outflows and to measure the level of impact that they have on their host galaxies.

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

    NASA Astrophysics Data System (ADS)

    Raginski, I.; Laor, Ari

    2016-06-01

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

  16. Star Formation and AGN Activity in Galaxy Clusters from z=1-2: a Multi-Wavelength Analysis Featuring Herschel/PACS

    NASA Astrophysics Data System (ADS)

    Alberts, Stacey; Pope, Alexandra; Brodwin, Mark; Chung, Sun Mi; Cybulski, Ryan; Dey, Arjun; Eisenhardt, Peter R. M.; Galametz, Audrey; Gonzalez, Anthony H.; Jannuzi, Buell T.; Stanford, S. Adam; Snyder, Gregory F.; Stern, Daniel; Zeimann, Gregory R.

    2016-07-01

    We present a detailed, multi-wavelength study of star formation (SF) and active galactic nucleus (AGN) activity in 11 near-infrared (IR) selected, spectroscopically confirmed massive (≳1014 M ⊙) galaxy clusters at 1 < z < 1.75. Using new deep Herschel/PACS imaging, we characterize the optical to far-IR spectral energy distributions (SEDs) for IR-luminous cluster galaxies, finding that they can, on average, be well described by field galaxy templates. Identification and decomposition of AGNs through SED fittings allows us to include the contribution to cluster SF from AGN host galaxies. We quantify the star-forming fraction, dust-obscured SF rates (SFRs) and specific SFRs for cluster galaxies as a function of cluster-centric radius and redshift. In good agreement with previous studies, we find that SF in cluster galaxies at z ≳ 1.4 is largely consistent with field galaxies at similar epochs, indicating an era before significant quenching in the cluster cores (r < 0.5 Mpc). This is followed by a transition to lower SF activity as environmental quenching dominates by z ∼ 1. Enhanced SFRs are found in lower mass (10.1\\lt {log} {M}\\star /{M}ȯ \\lt 10.8) cluster galaxies. We find significant variation in SF from cluster to cluster within our uniformly selected sample, indicating that caution should be taken when evaluating individual clusters. We examine AGNs in clusters from z = 0.5–2, finding an excess AGN fraction at z ≳ 1, suggesting environmental triggering of AGNs during this epoch. We argue that our results—a transition from field-like to quenched SF, enhanced SF in lower mass galaxies in the cluster cores, and excess AGNs—are consistent with a co-evolution between SF and AGNs in clusters and an increased merger rate in massive halos at high redshift.

  17. The PEP survey: evidence for intense star-forming activity in the majority of radio-selected AGN at z ≳ 1

    NASA Astrophysics Data System (ADS)

    Magliocchetti, M.; Lutz, D.; Santini, P.; Salvato, M.; Popesso, P.; Berta, S.; Pozzi, F.

    2016-02-01

    In order to investigate the far-infrared (FIR) properties of radio-active active galactic nuclei (AGN), we have considered three different fields where both radio and FIR observations are the deepest to date: GOODS-South, GOODS-North and the Lockman Hole. Out of a total of 92 radio-selected AGN, ˜64 per cent are found to have a counterpart in Herschel maps. The percentage is maximum in the GOODS-North (72 per cent) and minimum (˜50 per cent) in the Lockman Hole, where FIR observations are shallower. Our study shows that in all cases FIR emission is associated with star-forming activity within the host galaxy. Such an activity can even be extremely intense, with star-forming rates as high as ˜103-104 M⊙ yr-1. AGN activity does not inhibit star formation in the host galaxy, just as on-site star formation does not seem to affect AGN properties, at least those detected at radio wavelengths and for z ≳ 1. Given the very high rate of FIR detections, we stress that this refers to the majority of the sample: most radio-active AGN are associated with intense episodes of star formation. However, the two processes proceed independently within the same galaxy, at all redshifts but in the local universe, where powerful enough radio activity reaches the necessary strength to switch off the on-site star formation. Our data also show that for z ≳ 1 the hosts of radio-selected star-forming galaxies and AGN are indistinguishable from each other in terms of both mass and IR luminosity distributions. The two populations only differentiate in the very local universe, whereby the few AGN which are still FIR-active are found in galaxies with much higher masses and luminosities.

  18. Narrow-line X-Ray-selected Galaxies in the Chandra-COSMOS Field. II. Optically Elusive X-Ray AGNs

    NASA Astrophysics Data System (ADS)

    Pons, E.; Elvis, M.; Civano, F.; Watson, M. G.

    2016-06-01

    In the Chandra-COSMOS (C-COSMOS) survey, we have looked for X-ray-selected active galactic nuclei (AGNs), which are not detected as such in the optical, the so-called elusive AGNs. A previous study based on XMM-Newton and Sloan Digital Sky Survey observations has found a sample of 31 X-ray AGNs optically misclassified as star-forming (SF) galaxies at z\\lt 0.4, including 17 elusive Sy2s. Using Chandra observations provides a sample of fainter X-ray sources and so, for a given X-ray luminosity, extends to higher redshifts. To study the elusive Sy2s in the C-COSMOS field, we have removed the NLS1s that contaminate the narrow-line sample. Surprisingly, the contribution of NLS1s is much lower in the C-COSMOS sample (less than 10% of the optically misclassified X-ray AGNs) than in Pons & Watson. The optical misclassification of the X-ray AGNs ({L}{{X}}\\gt {10}42 {erg} {{{s}}}-1) can be explained by the intrinsic weakness of these AGNs, in addition to, in some cases, optical dilution by the host galaxies. Interestingly, we found the fraction of elusive Sy2s (narrow emission-line objects) optically misclassified as SF galaxies up to z∼ 1.4 to be 10% ± 3% to 17% ± 4%, compared to the 6% ± 1.5% of the Pons & Watson work (up to z∼ 0.4). This result seems to indicate an evolution with redshift of the number of elusive Sy2s.

  19. 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

  20. 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.

  1. 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.

  2. The New Spectral Picture of Seyfert 1 AGNs

    NASA Astrophysics Data System (ADS)

    Miyake, K.; Noda, H.; Yamada, S.; Makishima, K.

    2014-07-01

    X-ray spectra of active galactic nuclei (AGNs) were so far considered to consist of a single power-law (PL) like primary component and a reflection component accompanied by an FeKα line. However, the assumption of ``single primary component'' has not been confirmed observationally. To overcome this limitation, we developed a method that can decompose observed AGN spectra model-independently using time-variability (Noda et al. 2011, 2013). We applied it to the bright and variable Seyfert 1 AGN, IC4329A. It was observed by Suzaku 5 times in 2007, and once in 2012. Using our method, the time-averaged spectra have been successfully decomposed into a fast-variable component and a slowly-variable one. While the former can be regarded as a PL with photon index Γ~2.1, the latter is explained as a sum of the distant reflection component and a harder PL with Γ~1.4. This harder PL component, observed in all observations of IC 4329A and in many other AGNs (Noda et al. 2011, 2013), can be interpreted neither as partially-covered Γ~2.1 PL, nor relativistic reflection that varies with the primary. Therefore, the Γ~1.4 PL is considered to be another primary component. Its recognition has a big impact on our understanding of the AGN central engine.

  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. A Meeting on the AGN/Galaxy Connection

    NASA Technical Reports Server (NTRS)

    Kinney, Anne

    1999-01-01

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

  5. Large-scale clustering measurements with photometric redshifts: comparing the dark matter haloes of X-ray AGN, star-forming and passive galaxies at z ≈ 1

    NASA Astrophysics Data System (ADS)

    Georgakakis, A.; Mountrichas, G.; Salvato, M.; Rosario, D.; Pérez-González, P. G.; Lutz, D.; Nandra, K.; Coil, A.; Cooper, M. C.; Newman, J. A.; Berta, S.; Magnelli, B.; Popesso, P.; Pozzi, F.

    2014-10-01

    We combine multi-wavelength data in the AEGIS-XD and C-COSMOS surveys to measure the typical dark matter halo mass of X-ray selected active galactic nuclei (AGN) [LX(2-10 keV) > 1042 erg s- 1] in comparison with far-infrared selected star-forming galaxies detected in the Herschel/PEP survey (PACS Evolutionary Probe; LIR > 1011 L⊙) and quiescent systems at z ≈ 1. We develop a novel method to measure the clustering of extragalactic populations that uses photometric redshift probability distribution functions in addition to any spectroscopy. This is advantageous in that all sources in the sample are used in the clustering analysis, not just the subset with secure spectroscopy. The method works best for large samples. The loss of accuracy because of the lack of spectroscopy is balanced by increasing the number of sources used to measure the clustering. We find that X-ray AGN, far-infrared selected star-forming galaxies and passive systems in the redshift interval 0.6 < z < 1.4 are found in haloes of similar mass, log MDMH/(M⊙ h-1) ≈ 13.0. We argue that this is because the galaxies in all three samples (AGN, star-forming, passive) have similar stellar mass distributions, approximated by the J-band luminosity. Therefore, all galaxies that can potentially host X-ray AGN, because they have stellar masses in the appropriate range, live in dark matter haloes of log MDMH/(M⊙ h-1) ≈ 13.0 independent of their star formation rates. This suggests that the stellar mass of X-ray AGN hosts is driving the observed clustering properties of this population. We also speculate that trends between AGN properties (e.g. luminosity, level of obscuration) and large-scale environment may be related to differences in the stellar mass of the host galaxies.

  6. 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).

  7. 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.

  8. The Triggering and Evolution of AGN in Cluster Fields

    NASA Astrophysics Data System (ADS)

    Allen, Steven

    It is now well established that the evolution of super-massive black holes (SMBHs) is closely linked to that of their host galaxies. However, the detailed causal connections behind this relationship remain largely unknown. This is due in part to the complex diversity of active galactic nuclei (AGN) properties, the differing time-scales for AGN and star-forming processes, and a variety of observational selection effects. Physically, a prerequisite for both AGN activity and the formation of new stars in the host galaxy is the availability of gas. Environmental processes in galaxy clusters can strongly and rapidly affect gas reservoirs. Observations of star-forming galaxies in clusters have shown that the cluster environment drives evolution at a different rate than in the field. We here propose to make new measurements of the distribution of X-ray selected AGN, within cluster fields, and of their infrared (IR) and ultra-violet (UV) host galaxy properties to better understand the AGN triggering process, and the physical links between the SMBHs and their host galaxies. With a combination of superb spatial resolution and excellent sensitivity, Chandra X-ray observations have revolutionised studies of AGN evolution. The X-ray waveband is optimally suited for AGN surveys suffering little contamination from the host galaxy and only modest absorption bias, down to luminosities of 10^43 erg/s and across a wide range of source redshifts, providing direct access to a significant fraction of the total accretion power in the Universe (Brandt & Alexander 2015). However, two significant challenges exist that limit current studies of X-ray AGN in clusters: 1) the expense of optical follow-up of X-ray point source targets in order to confirm cluster membership; and 2) the low number of X-ray AGN that reside in clusters (typically 2-3 per cluster) relative to the background population (9,800 deg^2 in the deepest Chandra fields). In Ehlert et al. (2013, 2014 and 2015) we presented a

  9. 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.

  10. The merging/AGN connection: a case for 3D spectroscopy

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Christensen, L.; Becker, T.; Kelz, A.; Jahnke, K.; Benn, C. R.; García-Lorenzo, B.; Roth, M. M.

    2004-02-01

    We discuss an ongoing study of the connection between galaxy merging/interaction and AGN activity, based on integral field spectroscopy. We focus on the search for AGN ionization in the central regions of mergers, previously not classified as AGNs. We present here the science case, the current status of the project, and plans for future observations.

  11. Soft X-Ray Spectra of AGN Discovered Via Their Hard X-Ray

    NASA Technical Reports Server (NTRS)

    Schwartz, Daniel

    1998-01-01

    This final report is a study of the Active Galactic Nuclei (AGN). Investigation of the soft x-ray spectra of AGN were performed by using their hard x-ray emission. ROSAT observations of AGN was also performed, which allowed for the study of these x-ray spectra and the structures of 7 clusters of galaxies.

  12. On the electron-positron cascade in AGN central engines

    NASA Astrophysics Data System (ADS)

    Ford, Alex; Keenan, Brett; Medvedev, Mikhail

    2016-03-01

    Processes around spinning supermassive black holes (BH) in active galactic nuclei (AGN) are believed to determine how relativistic jets are launched and how the BH energy is extracted. The key ``ingredient'' is the origin of plasma in BH magnetospheres. In order to explore the process of the electron-positron plasma production, we developed a numerical code which models a one-dimensional (along a magnetic field line) dynamics of the cascade. Our simulations show that plasma production is controlled by the spectrum of the ambient photon field, the B-field strength, the BH spin and mass. Implications of our results to the Galactic Center and AGNs are discussed.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. High precision X-ray log N - log S distributions: implications for the obscured AGN population

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Warwick, R. S.; Carrera, F. J.; Stewart, G. C.; Ebrero, J.; Della Ceca, R.; Caccianiga, A.; Gilli, R.; Page, M. J.; Treister, E.; Tedds, J. A.; Watson, M. G.; Lamer, G.; Saxton, R. D.; Brunner, H.; Page, C. G.

    2008-12-01

    Context: Our knowledge of the properties of AGN, especially those of optical type-2 objects, is very incomplete. Because extragalactic source count distributions are dependent on the cosmological and statistical properties of AGN, they provide a direct method of investigating the underlying source populations. Aims: We aim to constrain the extragalactic source count distributions over a broad range of X-ray fluxes and in various energy bands to test whether the predictions from X-ray background synthesis models agree with the observational constraints provided by our measurements. Methods: We have used 1129 XMM-Newton observations at |b|>20° covering a total sky area of 132.3 deg2 to compile the largest complete samples of X-ray selected objects to date both in the 0.5-1 keV, 1-2 keV, 2-4.5 keV, 4.5-10 keV bands employed in standard XMM-Newton data processing and in the 0.5-2 keV and 2-10 keV energy bands more usually considered in source count studies. Our survey includes in excess of 30 000 sources and spans fluxes from 10-15 to 10-12 erg cm^{-2 s-1} below 2 keV and from 10-14 to 10-12 erg cm^{-2 s-1} above 2 keV where the bulk of the cosmic X-ray background energy density is produced. Results: The very large sample size we obtained means our results are not limited by cosmic variance or low counting statistics. A break in the source count distributions was detected in all energy bands except the 4.5-10 keV band. We find that an analytical model comprising 2 power-law components cannot adequately describe the curvature seen in the source count distributions. The shape of the log N(>S) - log S is strongly dependent on the energy band with a general steepening apparent as we move to higher energies. This is due to the fact that non-AGN populations, comprised mainly of stars and clusters of galaxies, contribute up to 30% of the source population at energies <2 keV and at fluxes ≥10-13 erg cm^{-2 s-1}, and these populations of objects have significantly flatter

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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…

  6. Disc outflows and high-luminosity true type 2 AGN

    NASA Astrophysics Data System (ADS)

    Elitzur, Moshe; Netzer, Hagai

    2016-06-01

    The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such `true type 2 AGN' are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad-line emission can disappear at luminosities as high as ˜4 × 1046 erg s-1 and any Eddington ratio, though more detections can be expected at Eddington ratios below ˜1 per cent. Our results are applicable to every disc outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. While other factors, such as changes in spectral energy distribution or covering factor, can affect the intensities of broad emission lines, within this scenario they can only produce true type 2 AGN of higher luminosity then those prescribed by mass conservation.

  7. FLOYDS Classification of Gaia16ann as an AGN

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Arcavi, I.; Howell, D. A.; McCully, C.; Valenti, S.

    2016-07-01

    We obtained a spectrum of Gaia16ann on 2016 July 7.5 UT with the robotic FLOYDS instrument mounted on the LCOGT 2-meter telescope on Haleakala, Hawai'i. Using SNID (Blondin & Tonry 2007, ApJ, 666, 1024), we find a good fit to an AGN at redshift z=0.196.

  8. New light on obscured accretion in nearby AGN

    NASA Astrophysics Data System (ADS)

    Arevalo, Patricia

    Analyses of the Cosmic X-ray Background have shown that a substantial fraction of the black hole growth in the Universe occurred behind dense clouds of obscuring material. As such, it is critical to the study the detailed spectral characteristics of nearby obscured black holes, which provide templates for deriving accurate physical parameters from more distant obscured accretors. Hard X-rays are important in this regard, allowing us to peer more directly into the central engine of obscured sources and constrain the nature of the obscuration. The recently launched NuSTAR telescope is unique at focusing hard X-rays, producing the lowest background-contaminated spectra to date and rendering accurate, high signal-to-noise spectra up to 80 keV. NuSTAR covers precisely the energy range where the main features of obscured accretion appear and where the intrinsic emission might even shine through. Importantly, the low level of background also allows us for the first time to measure rapid variability of AGN at high X-ray energies. Both features combined are revealing the detailed nature of the engine of nearby obscured AGN, including the properties of the obscurer, the intrinsic emitted flux of the AGN and whether or not we can see through the torus at these high energies. In this talk I will show how NuSTAR data is challenging past assumptions about even the very local obscured AGN.

  9. Time Series Analysis of the UV Flickering in AGN

    NASA Technical Reports Server (NTRS)

    Robinson, Edward L.; Welsh, William F.

    2001-01-01

    Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability. We hoped to answer these specific questions: 1) What does the intrinsic flickering continuum spectrum look like? 2) What do the intrinsic flickering emission-line profiles look like? 3) What is the power spectrum of the flickering? 4) What is the wavelength dependence of the power spectrum? 5) Is the flickering spectrum timescale dependent? and 6) What do the high-order cross correlation functions look like? A short summary of the papers produced by this research is presented.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. A Degeneracy in DRW Modelling of AGN Light Curves

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-04-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well-modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light curve modelling.

  15. Sexual Freedom Rights for Adolescents? A Rejoinder to Agnes Tellings

    ERIC Educational Resources Information Center

    Steutel, Jan

    2009-01-01

    Agnes Tellings rightly observes that adolescents, if compared with pre-pubescent children, are much more capable of making their own choices and therefore should be granted much more freedom to arrange their own lives. However, the capacity of adolescents to make prudent choices still seems to be below the threshold of competence. Therefore,…

  16. Agnes Mary Clerke: Ever-popular historian of astronomy

    NASA Astrophysics Data System (ADS)

    Brück, M.

    In her day, Agnes Mary Clerke (1842-1907) was the English-speaking world's most highly regarded writer on the rapidly developing science of astrophysics. This account outlines how, without any formal education but with a deep interest in learning, this remarkable woman rose to the admired position she still holds as a leading historian of astronomy and astrophysics.

  17. A degeneracy in DRW modelling of AGN light curves

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-07-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time-scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light-curve modelling.

  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}ȯ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ∼ 2.0× {10}10 {M}ȯ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  19. Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555

    NASA Astrophysics Data System (ADS)

    Satyapal, S.; Secrest, N. J.; Rothberg, B.; O’Connor, J. A.; Ellison, S. L.; Hickox, R. C.; Constantin, A.; Gliozzi, M.; Rosenberg, J. L.

    2016-08-01

    There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3σ level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of {L}2-10{keV}=(1.1+/- 0.4)× {10}40 erg s‑1. Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of {N}{{H}}\\gt {10}24 cm‑2. The hard X-ray luminosity of the putative AGN corrected for absorption is {L}2-10{keV}˜ 3× {10}42 erg s‑1, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of {L}{bol}.˜ 6× {10}43‑3 × 1044 {erg} {{{s}}}-1 and a lower mass limit for the black hole of {M}{BH}≃ 2× {10}6 {M}ȯ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ˜ 2.0× {10}10 {M}ȯ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  20. 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.

  1. 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

  2. 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

  3. Dependence of the broad Fe Kα line on the physical parameters of AGN

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Yuan, Weimin; Lu, Youjun; Carrera, Francisco J.; Falocco, Serena; Dong, Xiao-Bo

    2016-08-01

    In this paper, the dependence of the broad Fe Kα line on the physical parameters of AGN, such as the black hole mass MBH, accretion rate (equivalently represented by Eddington ratio λEdd), and optical classification, is investigated by applying the X-ray spectra stacking method to a large sample of AGN which have well measured optical parameters. A broad line feature is detected (>3σ) in the stacked spectra of the high λEdd sub-sample (log λEdd > -0.9). The profile of the broad line can be well fitted with relativistic broad line model, with the line energy consistent with highly ionized Fe Kα line (i.e. Fe XXVI). A model consisting of multiple narrow lines cannot be ruled out, however. We found hints that the Fe K line becomes broader as the λEdd increases. No broad line feature is shown in the sub-sample of broad-line Seyfert 1 (BLS1) galaxies and in the full sample, while a broad line might be present, though at low significance, in the sub-sample of narrow-line Seyfert 1 (NLS1) galaxies. We find no strong dependence of the broad line on black hole masses. Our results indicate that the detection/properties of the broad Fe Kα line may strongly depend on λEdd, which can be explained if the ionization state and/or truncation radius of the accretion disc changes with λEdd. The non-detection of the broad line in the BLS1 sub-sample can be explained if the the average EW of the relativistic Fe Kα line is weak or/and the fraction of sources with relativistic Fe Kα line is small in BLS1 galaxies.

  4. STUDYING FAINT ULTRA-HARD X-RAY EMISSION FROM AGN IN GOALS LIRGS WITH SWIFT/BAT

    SciTech Connect

    Koss, Michael; Casey, Caitlin M.; Mushotzky, Richard; Veilleux, Sylvain; Baumgartner, Wayne; Tueller, Jack; Markwardt, Craig

    2013-03-10

    We present the first analysis of the all-sky Swift Burst Alert Telescope (BAT) ultra-hard X-ray (14-195 keV) data for a targeted list of objects. We find that the BAT data can be studied at three-times-fainter limits than in previous blind detection catalogs based on prior knowledge of source positions and using smaller energy ranges for source detection. We determine the active galactic nucleus (AGN) fraction in 134 nearby (z < 0.05) luminous infrared galaxies (LIRGs) from the GOALS sample. We find that LIRGs have a higher detection frequency than galaxies matched in stellar mass and redshift at 14-195 keV and 24-35 keV. In agreement with work at other wavelengths, the AGN detection fraction increases strongly at high IR luminosity with half of the high-luminosity LIRGs (50%, 6/12, log L{sub IR}/L{sub Sun} > 11.8) detected. The BAT AGN classification shows 97% (37/38) agreement with Chandra and XMM-Newton AGN classification using hardness ratios or detection of an iron K{alpha} line. This confirms our statistical analysis and supports the use of the Swift/BAT all-sky survey to study fainter populations of any category of sources in the ultra-hard X-ray band. BAT AGNs in LIRGs tend to show higher column densities with 40% {+-} 9% showing 14-195 keV/2-10 keV hardness flux ratios suggestive of high or Compton-thick column densities (log N{sub H} > 24 cm{sup -2}), compared to only 12% {+-} 5% of non-LIRG BAT AGNs. We also find that using specific energy ranges of the BAT detector can yield additional sources over total band detections with 24% (5/21) of detections in LIRGs at 24-35 keV not detected at 14-195 keV.

  5. Current and Future X-ray Studies of High-Redshift AGNs and the First Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    Brandt, Niel

    2016-01-01

    X-ray observations of high-redshift AGNs at z = 4-7 have played a critical role in understanding the physical processes at work inthese objects as well as their basic demographics. Since 2000, Chandra and XMM-Newton have provided new X-ray detections for more than 120 such objects, and well-defined samples of z > 4 AGNs now allow reliable X-ray population studies. Once luminosity effectsare considered, the basic X-ray continuum properties of most high-redshift AGNs appear remarkably similar to those of local AGNs, although there are some notable apparent exceptions (e.g., highly radio-loud quasars). Furthermore, the X-ray absorption found in some objects has been used as a diagnostic of outflowing winds and circumnuclear material. Demographically, the X-ray data now support an exponential decline in the number density of luminous AGNs above z ~ 3, and quantitative space-density comparisons for optically selected and X-ray selected quasars indicate basic statistical agreement.The current X-ray discoveries point the way toward the future breakthroughs that will be possible with, e.g., Athena and the X-raySurveyor. These missions will execute powerful blank-field surveys to elucidate the demographics of the first growing supermassive black holes (SMBHs), including highly obscured systems, up to z ~ 10. They will also carry out complementary X-ray spectroscopic and variability investigations of high-redshift AGNs by targeting the most-luminous z = 7-10 quasars found in wide-field surveys by, e.g., Euclid, LSST, and WFIRST. X-ray spectroscopic and variability studies of the X-ray continuum and reflection signatures will help determine Eddington ratios and disk/corona properties; measuring these will clarify how the first quasars grew so quickly. Furthermore, absorption line/edge studies will reveal how outflows from the first SMBHs influenced the growth of the first galaxies. I will suggest some efficient observational strategies for Athena and the X-ray Surveyor.

  6. 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.

  7. THE LICK AGN MONITORING PROJECT: REVERBERATION MAPPING OF OPTICAL HYDROGEN AND HELIUM RECOMBINATION LINES

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Thornton, Carol E.; Yoshii, Yuzuru; Sakata, Yu; Minezaki, Takeo; Woo, Jong-Hak; Malkan, Matthew A.; Wang, Xiaofeng; Steele, Thea N.; Silverman, Jeffrey M.; Serduke, Frank J. D.; Li, Weidong; Lee, Nicholas; Treu, Tommaso; Street, Rachel A.; Hidas, Marton G.; Hiner, Kyle D.; Greene, Jenny E.

    2010-06-20

    We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range {approx}10{sup 6}-10{sup 7} M{sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad H{beta} emission, which we have previously reported. We present here the light curves for the H{alpha}, H{gamma}, He II {lambda}4686, and He I {lambda}5876 emission lines and the time lags for the emission-line responses relative to changes in the continuum flux. Combining each emission-line time lag with the measured width of the line in the variable part of the spectrum, we determine a virial mass of the central supermassive black hole from several independent emission lines. We find that the masses are generally consistent within the uncertainties. The time-lag response as a function of velocity across the Balmer line profiles is examined for six of the AGNs. We find similar responses across all three Balmer lines for Arp 151, which shows a strongly asymmetric profile, and for SBS 1116+583A and NGC 6814, which show a symmetric response about zero velocity. For the other three AGNs, the data quality is somewhat lower and the velocity-resolved time-lag response is less clear. Finally, we compare several trends seen in the data set against the predictions from photoionization calculations as presented by Korista and Goad. We confirm several of their predictions, including an increase in responsivity and a decrease in the mean time lag as the excitation and ionization level for the species increases. Specifically, we find the time lags of the optical

  8. 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.

  9. 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.

  10. The most luminous H α emitters at z ˜ 0.8-2.23 from HiZELS: evolution of AGN and star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Sobral, David; Kohn, Saul A.; Best, Philip N.; Smail, Ian; Harrison, Chris M.; Stott, John; Calhau, João; Matthee, Jorryt

    2016-04-01

    We use new near-infrared spectroscopic observations to investigate the nature and evolution of the most luminous Hα emitters at z ˜ 0.8-2.23, which evolve strongly in number density over this period, and compare them to more typical Hα emitters. We study 59 luminous Hα emitters with LHα > L_{Hα }^{ast }, roughly equally split per redshift slice at z ˜ 0.8, 1.47 and 2.23 from the HiZELS and CF-HiZELS surveys. We find that, overall, 30 ± 8 per cent are active galactic nuclei [AGNs; 80 ± 30 per cent of these AGNs are broad-line AGNs, BL-AGNs], and we find little to no evolution in the AGN fraction with redshift, within the errors. However, the AGN fraction increases strongly with Hα luminosity and correlates best with LHα/L_{Hα }^{ast }(z). While LHα ≤ L_{Hα }^{ast }(z) Hα emitters are largely dominated by star-forming galaxies (>80 per cent), the most luminous Hα emitters (L_{Hα }>10L_{Hα }^{ast }(z)) at any cosmic time are essentially all BL-AGN. Using our AGN-decontaminated sample of luminous star-forming galaxies, and integrating down to a fixed Hα luminosity, we find a factor of ˜1300 evolution in the star formation rate density from z = 0 to 2.23. This is much stronger than the evolution from typical Hα star-forming galaxies and in line with the evolution seen for constant luminosity cuts used to select `ultraluminous' infrared galaxies and/or sub-millimetre galaxies. By taking into account the evolution in the typical Hα luminosity, we show that the most strongly star-forming Hα-selected galaxies at any epoch (L_{Hα }>L^{ast }_{Hα }(z)) contribute the same fractional amount of ≈15 per cent to the total star formation rate density, at least up to z = 2.23.

  11. The Suzaku view of highly ionized outflows in AGN - II. Location, energetics and scalings with bolometric luminosity

    NASA Astrophysics Data System (ADS)

    Gofford, J.; Reeves, J. N.; McLaughlin, D. E.; Braito, V.; Turner, T. J.; Tombesi, F.; Cappi, M.

    2015-08-01

    Ongoing studies with XMM-Newton have shown that powerful accretion disc winds, as revealed through highly ionized Fe K-shell absorption at E ≥ 6.7 keV, are present in a significant fraction of active galactic nuclei (AGNs) in the local Universe (Tombesi et al. 2010a). In Gofford et al., we analysed a sample of 51 Suzaku-observed AGNs and independently detected Fe K absorption in ˜40 per cent of the sample, and we measured the properties of the absorbing gas. In this work, we build upon these results to consider the properties of the associated wind. On average, the fast winds (vw > 0.01c) are located ˜ 1015-18 cm (typically ˜102-4 rs) from their black hole, their mass outflow rates are of the order of < dot{M}_w > ˜ 0.01-1 M⊙ yr-1 or {˜ }(0.01-1)dot{M}_Edd and kinetic power is constrained to ˜ 1043-45 erg s-1, equivalent to ˜(0.1-10 per cent)LEdd. We find a fundamental correlation between the source bolometric luminosity and the wind velocity, with v_w ∝ L_bol^{α } and α =0.4^{+0.3}_{-0.2} (90 per cent confidence), which indicates that more luminous AGN tend to harbour faster Fe K winds. The mass outflow rate dot{M}_w, kinetic power Lw and momentum flux dot{p}_w of the winds are also consequently correlated with Lbol, such that more massive and more energetic winds are present in more luminous AGN. We investigate these properties in the framework of a continuum-driven wind, showing that the observed relationships are broadly consistent with a wind being accelerated by continuum-scattering. We find that, globally, a significant fraction (˜85 per cent) of the sample can plausibly exceed the Lw/Lbol ˜ 0.5 per cent threshold thought necessary for feedback, while 45 per cent may also exceed the less conservative ˜5 per cent of Lbol threshold as well. This suggests that the winds may be energetically significant for AGN-host-galaxy feedback processes.

  12. AGN Search From Multicolor CCD Photometric Observations of Faint ROSAT X-ray Sources in a One Square Degree Field

    NASA Astrophysics Data System (ADS)

    Xue, Suijian; Zhou, Xu; Zhang, H.

    We present the optical identifications of 75 X-ray sources in a 1 sq. deg. overlapping region, T329 of BATC sky survey with a medium deep ROSAT survey (Molthagen et al. 1997), based on multi-color CCD imaging observations made for the T329 utilizing BAO 60/90 cm Schmidt telescope with 15 intermediate-band filters covering the wavelength range 3360-9745 AA. These X-ray sources are relatively faint (CR << 0.2 s-1) and thus mostly are not included in the RBS catalogue and also remained as unidentified sources in a previous identification program carried out by the Hamburg Quasar Survey. Within their position-error circles, All of the X-ray sources were observed to have one or more spatially associated optical counterparts down to the magnitude mv=21.5. The majority of these optical objects could be classified according to their SED information constructed from the 15 color photometric catalogue of T329. This finally leads to 43 (~57%) of 75 X-ray sources are identified with AGNs, 19 (~25%) and 8 (~11%) are identified with various types of galaxies and late stars respectively. About one third sources in the AGN list (including 4 known AGNs) have follow up spectroscopic observations, confirming their QSO/Seyfert or NELG nature. Further more spectroscopic observations are partially ongoing with the Multiple Object Fiber Spectrograph (MOFS) of SAO 6m telescope, which will help to form a complete, X-ray flux limited AGN sample in a 1 square degree field.

  13. The relationship between radio power at 22 and 43 GHz and black hole properties of AGN in elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Park, Songyoun; Sohn, Bong Won; Yi, Sukyoung K.

    2013-12-01

    We investigate the relationship between radio power and properties related to active galactic nuclei (AGNs). Radio power at 1.4 or 5 GHz, which has been used in many studies, can be affected by synchrotron self-absorption and free-free absorption in a dense region. On the other hand, these absorption effects get smaller at higher frequencies. Thus, we performed simultaneous observations at 22 and 43 GHz using the Korean VLBI Network (KVN) radio telescope based on a sample of 305 AGN candidates residing in elliptical galaxies from the overlap between the Sloan Digital Sky Survey (SDSS) Data Release 7 and Faint Images of the Radio Sky at Twenty-Centimeters (FIRST). About 37% and 22% of the galaxies are detected at 22 and 43 GHz, respectively. Assuming no flux variability between the FIRST and KVN observations, spectral indices were derived from FIRST and KVN data and we found that over 70% of the detected galaxies have flat or inverted spectra, implying the presence of optically thick compact regions near the centres of the galaxies. Core radio power does not show a clear dependence on black hole mass at either low (1.4 GHz) or high (22 and 43 GHz) frequencies. However, we found that the luminosity of the [OIII] λ5007 emission line and the Eddington ratio correlate with radio power more closely at high frequencies than at low frequencies. This suggests that radio observation at high frequencies can be an appropriate tool for unveiling the innermost region. In addition, the luminosity of the [OIII] λ5007 emission line and the Eddington ratio can be used as a tracer of AGN activity. Our study suggests a causal connection between high frequency radio power and optical properties of AGNs. Table 5 is available in electronic form at http://www.aanda.org

  14. Comparison of spatial and angular clustering of X-ray AGN

    NASA Astrophysics Data System (ADS)

    Koutoulidis, L.; Plionis, M.; Georgantopoulos, I.; Georgakakis, A.; Akylas, A.; Basilakos, S.; Mountrichas, G.

    2016-05-01

    The angular correlation function is a powerful tool for deriving the clustering properties of active galactic nuclei (AGN) and hence the mass of the corresponding dark matter halos in which they reside. However, recent studies based on the application of the angular correlation function on X-ray samples, yield results that are apparently inconsistent with those based on the direct estimation of the spatial correlation function. The goal of the present paper is to attempt to investigate this issue by analysing a well-defined sample. To this end we use the hard-band (2-10 keV) X-ray selected sources of the Chandra AEGIS fields, chosen because of the availability of accurately derived flux sensitivity maps. In particular we use the 186 hard-band sources with spectroscopic redshifts in the range z = 0.3-1.3, a range selected in order to contain the bulk of the AGN while minimizing the contribution of unknown clustering and luminosity evolution from very high redshifts. Using the projected spatial auto-correlation function, we derive a comoving clustering length of x0 = 5.4 ± 1.0h-1 Mpc (for γ = 1.8), which is consistent with results in the literature. We further derive the angular correlation function and corresponding spatial clustering length using the Limber's inversion equation and a novel parametrization of the clustering evolution model that also takes the bias evolution of the host dark matter halo into account. The Limber's inverted spatial comoving clustering length of x0 = 5.5 ± 1.2h-1 Mpc at a median redshift of z ≃ 0.75 matches the clustering length that is directly measured from the spatial correlation function analysis, but after introducing a significant non-linear contribution to the growing mode of perturbations; this contribution is estimated independently from literature results of x0 at different redshifts. Therefore, using this sample of hard X-ray AGN and our clustering evolution parametrization, we find an excellent consistency between the

  15. 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

  16. The stability of QSO/AGN broad emission line clouds

    NASA Astrophysics Data System (ADS)

    Krinsky, I. S.; Puetter, R. C.

    1992-08-01

    Results of a numerical linear stability analysis of QSO/AGN emission-line clouds (ELCs) embedded within a confining hot intercloud medium (HIM) are reported. A first-order linear perturbation analysis reveals two important ionstabilities. The first instability is thermal in nature and arises in the interface region between the HIM and the ELC where thermal convection dominates gas heating; the growth time of the instability is approximately 1000 s, resulting in an ELC evaporation time of about 10 yr. The second instability is dynamic in nature, with the sound wave amplitude growing in response to radiative forces. The growth time of this instability is about 10 exp 6 s and essentially independent of the wavelength. The results suggest that if QSO/AGN ELCs have properties similar to those of the standard ELC model, then the broad-line region is in a constant state of flux in which ELCs continually form, are destroyed, and then re-formed.

  17. Optically selected BLR-less active galactic nuclei from the SDSS Stripe82 Database - I. The sample

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-Guang

    2014-02-01

    This is the first paper in a dedicated series to study the properties of the optically-selected broad-line-region-less (BLR-less) active galactic nuclei (AGNs; with no-hidden central broad emission line regions). We carried out a systematic search for the BLR-less AGNs through the Sloan Digital Sky Survey Legacy Survey (SDSS Stripe82 Database). Based on the spectral decomposition results for all the 136 676 spectroscopic objects (galaxies and quasars) with redshift less than 0.35 covered by the SDSS Stripe82 region, our spectroscopic sample for the BLR-less AGNs includes 22 693 pure narrow line objects without broad emission lines but with apparent AGN continuum emission RAGN > 0.3 and apparent stellar lights Rssp > 0.3. Then, using the properties of the photometry magnitude RMS (RMS) and Pearson's coefficients (R1, 2) between two different SDSS band light curves: RMS_k>3× RMS_{M_k} and R1, 2 > ˜0.8, the final 281 pure narrow line objects with true photometry variabilities are our selected reliable candidates for the BLR-less AGNs. The selected candidates with higher confidence levels not only have the expected spectral features of the BLR-less AGNs, but also show significant true photometry variabilities. The reported sample enlarges at least four times the current sample of the BLR-less AGNs, and will provide more reliable information to explain the lack of the BLRs of AGNs in our following studies.

  18. Four Dual AGN Candidates Observed with the VLBA

    NASA Astrophysics Data System (ADS)

    Gabányi, K. É.; An, T.; Frey, S.; Komossa, S.; Paragi, Z.; Hong, X.-Y.; Shen, Z.-Q.

    2016-08-01

    According to hierarchical structure formation models, merging galaxies are expected to be seen in different stages of coalescence. However, there are currently no straightforward observational methods to either select or to confirm a large number of dual active galactic nucleus (AGN) candidates. Most attempts involve obtaining a better understanding of double-peaked narrow emission line sources, in order to distinguish the objects for which the emission lines originate from narrow-line kinematics or jet-driven outflows, from those which might harbor dual AGNs. We observed four such candidate sources with the Very Long Baseline Array (VLBA), at 1.5 GHz with a ∼10 mas angular resolution, for which the spectral profiles of AGN optical emission suggested the existence of dual AGNs. In SDSS J210449.13–000919.1 and SDSS J23044.82–093345.3 the radio structures are aligned with the optical emission features, thus the double-peaked emission lines might be the results of jet-driven outflows. In the third detected source SDSS J115523.74+150756.9, the radio structure is less extended and is oriented nearly perpendicular to the position angle derived from optical spectroscopy. The fourth source remained undetected with the VLBA, but it was imaged with the Very Large Array at arcsec resolution a few months before our observations, suggesting the existence of an extended radio structure. We did not detect two radio-emitting cores in any of the four sources, a convincing signature of duality.

  19. Observational aspects of AGN jets at high energy

    NASA Astrophysics Data System (ADS)

    Kataoka, Jun

    2015-03-01

    For the last two decades, significant and dramatic progress has been made in understanding astrophysical jet sources, particularly in the X-ray and gamma-ray energy bands. For example, the Chandra X-ray observatory reveals a number of AGN jets extending from kpc to Mpc scales. More recently, the Fermi Gamma-ray Space Telescopes launched in 2008 started monitoring the gamma-ray sky with excellent sensitivity of about ten times greater than that of EGRET onboard CGRO, and has detected more than 2,000 sources (mostly AGNs) as of 2014. Moreover, Fermi-LAT has discovered gamma-ray emissions not only from blazars but from a dozen radio galaxies not previously known to emit gamma-rays. Closer to home, the Fermi-bubbles were discovered to extend 50 degrees above and below the Galactic center. These large scale diffuse gamma-ray structures are similar in structure to AGN lobes such as those seen in Cen A and provide evidence for past activity in our Galactic center. In this review, I will first summarize recent highlights of large scale jets in radio galaxies, specifically resolved by the Chandra X-ray observatory. Next I will move on to the gamma-ray sky to present some highlights from Fermi-LAT observations of ``misaligned'' blazars, namely radio galaxies. I will discuss a unification scheme connecting blazars and misaligned radio galaxies. In the last part, I will also briefly comment on recent multiband observations of the Fermi-bubble and possible impacts on the AGN jet physics in the near future.

  20. Alignment of Stellar and AGN Accretion Disks from SDSS Data

    NASA Astrophysics Data System (ADS)

    Lagos, Claudia del P.; Padilla, Nelson D.; Strauss, Michael A.; Hao, Lei

    2010-05-01

    Lagos, Padilla & Cora (2009) show that if alignments between the galaxy kinematics and the AGN system were to occur, massive galaxies should host BHs with high spin values, regardless of the detailed physics of the BH. Since the BH spin regulates the mass-to-energy conversion (Marconi et al. 2004) and possibly the existence of radio jets (Sikora et al. 2007), this study has a strong impact in our understanding of galaxy formation.

  1. Near-UV Snapshot Survey of Low Luminosity AGNs

    NASA Astrophysics Data System (ADS)

    Gonzalez-Delgado, Rosa

    2005-07-01

    Low-luminosity active galactic nuclei {LLAGNs} comprise 30% of all bright galaxies {B<12.5} and are the most common type of AGN. These include low-luminosity Seyfert galaxies, LINERs, and transition-type objects {TOs, also called weak-[OI] LINERs}. What powers them is still at the forefront of AGN research. To unveil the nature of the central source we propose a near-UV snapshot survey of 50 nearby LLAGNs using ACS/HRC and the filter {F330W}, a configuration which is optimal to detect faint star forming regions around their nuclei. These images will complement optical and near-IR images available in the HST archive, providing a panchromatic atlas of the inner regions of these galaxies, which will be used to study their nuclear stellar population. Our main goals are to: 1} Investigate the presence of nuclear unresolved sources that can be attributed to an AGN; 2} Determine the frequency of nuclear and circumnuclear stellar clusters, and whether they are more common in Transition Objects {TOs} than in LINERs; 3} Characterize the sizes, colors, luminosities, masses and ages of these clusters; 4} Derive the luminosity function of star clusters and study their evaporation over time in the vicinity of AGNs. Finally, the results of this project will be combined with those of a previous similar one for Seyfert galaxies in order to compare the nature of the nuclear sources and investigate if there could be an evolution from Seyferts to TOs and LINERs. By adding UV images to the existing optical and near-IR ones, this project will also create an extremely valuable database for astronomers with a broad range of scientific interests.

  2. 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.

  3. Suzaku Observations of AGN and Synergy with GLAST

    SciTech Connect

    Kataoka, Jun; Takahashi, Tad; Madejski, Greg; /KIPAC, Menlo Park

    2007-10-29

    In next five years, dramatic progress is anticipated for the AGN studies, as we have two important missions to observe celestial sources in the high energy regime: GLAST and Suzaku. Suzaku is the 5th Japanese X-ray astronomy satellite which was successfully launched in July 2005. It carries four X-ray sensitive imaging CCD cameras (0.2-12 keV) located in the focal planes of X-ray telescope, and a non-imaging, collimated hard X-ray detector, which extends the bandpass of the observatory to include the 10-600 keV range. Simultaneous monitoring observations by the two instruments (GLAST and Suzaku) will be particularly valuable for variable radio-loud AGN, allowing the cross-correlations of time series as well as detailed modeling of the spectral evolution between the X-ray and gamma-ray energy bands. In this paper, we show early highlights from Suzaku observations of radio-loud AGNs, and discuss what we can do with GLAST in forthcoming years.

  4. Probing the central parsecs of AGN using Faraday Rotation

    NASA Astrophysics Data System (ADS)

    Zavala, R. T.; Taylor, G. B.

    2002-05-01

    A broad frequency range and low instrumental polarization makes the Very Long Baseline Array (VLBA) an ideal instrument for studying polarimetry at sub-milliarcsecond resolution. To take advantage of these unique capabilities we have conducted a multi-frequency polarization survey of 40 radio-loud AGN (Quasars, BL Lacs, and radio galaxies). Our aim is to use Faraday Rotation Measures (RMs) as a probe of the central 1-50 parsecs of these objects. The RM is produced by the line of sight magnetic field weighted by the electron density. Using the electron density established through spectral line diagnostics a magnetic field strength and topology can be estimated within a few parsecs of the central engines of these AGN. The observations for the survey are complete, and we present the first results for 8 quasars, 5 BL Lacs, and 4 radio galaxies. The magnitudes for the RMs range from several thousand rad m-2 in the quasars and radio galaxies to a few hundred rad m-2 in the BL Lac objects. These values are in agreement with the basic ideas of the unified model for AGN. We also observe variations in the RM on small spatial (< ~ 1 pc) in radio galaxies and quasars; and short time scales ( ~ 6 months) in the quasars 3C 273 and 3C 279. R.T.Z. gratefully acknowledges support from a pre-doctoral research appointment at NRAO and from the New Mexico Alliance for Graduate Education and the Professiorate through NSF grant HRD-0086701.

  5. Doppler disc tomography applied to low-mass AGN spin

    NASA Astrophysics Data System (ADS)

    Middleton, Matthew J.; Ingram, Adam R.

    2015-01-01

    Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low-mass active galactic nuclei (AGN), time-dependent obscuration is expected to leave a signature in the changing spectrum of the disc emission which extends into the soft X-ray bandpass. We create a spectral model incorporating Doppler tomography and apply it to the case of the low-mass (8 × 105 M⊙) AGN, RX J1301.9+2747 which shows unusual timing properties in the form of short-lived flares that we argue are best explained by the orbit of a window through an optically thick wind. Modelling the phase-resolved spectrum over the course of the highest data quality flare indicates a very low spin even when we relax our constraints. This is the lowest mass AGN for which a spin has been measured and the first via this technique. We note that, as the mass and spin are very low, this appears to favour supermassive black hole (SMBH) growth by chaotic rather than constant accretion.

  6. Modeling AGN outbursts from supermassive black hole binaries

    NASA Astrophysics Data System (ADS)

    Tanaka, T.

    2012-12-01

    When galaxies merge to assemble more massive galaxies, their nuclear supermassive black holes (SMBHs) should form bound binaries. As these interact with their stellar and gaseous environments, they will become increasingly compact, culminating in inspiral and coalescence through the emission of gravitational radiation. Because galaxy mergers and interactions are also thought to fuel star formation and nuclear black hole activity, it is plausible that such binaries would lie in gas-rich environments and power active galactic nuclei (AGN). The primary difference is that these binaries have gravitational potentials that vary - through their orbital motion as well as their orbital evolution - on humanly tractable timescales, and are thus excellent candidates to give rise to coherent AGN variability in the form of outbursts and recurrent transients. Although such electromagnetic signatures would be ideally observed concomitantly with the binary's gravitational-wave signatures, they are also likely to be discovered serendipitously in wide-field, high-cadence surveys; some may even be confused for stellar tidal disruption events. I discuss several types of possible "smoking gun" AGN signatures caused by the peculiar geometry predicted for accretion disks around SMBH binaries.

  7. 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.

  8. Cycling of the powerful AGN in MS 0735.6+7421 and the duty cycle of radio AGN in clusters

    NASA Astrophysics Data System (ADS)

    Vantyghem, A. N.; McNamara, B. R.; Russell, H. R.; Main, R. A.; Nulsen, P. E. J.; Wise, M. W.; Hoekstra, H.; Gitti, M.

    2014-08-01

    We present an analysis of deep Chandra X-ray observations of the galaxy cluster MS 0735.6+7421, which hosts the most energetic radio active galactic nucleus (AGN) known. Our analysis has revealed two cavities in its hot atmosphere with diameters of 200-240 kpc. The total cavity enthalpy, mean age, and mean jet power are 9 × 1061 erg, 1.6 × 108 yr, and 1.7 × 1046 erg s-1, respectively. The cavities are surrounded by nearly continuous temperature and surface brightness discontinuities associated with an elliptical shock front of Mach number 1.26 (1.17-1.30) and age of 1.1 × 108 yr. The shock has injected at least 4 × 1061 erg into the hot atmosphere at a rate of 1.1 × 1046 erg s-1. A second pair of cavities and possibly a second shock front are located along the radio jets, indicating that the AGN power has declined by a factor of 30 over the past 100 Myr. The multiphase atmosphere surrounding the central galaxy is cooling at a rate of 40 M⊙yr-1, but does not fuel star formation at an appreciable rate. In addition to heating, entrainment in the radio jet may be depleting the nucleus of fuel and preventing gas from condensing out of the intracluster medium. Finally, we examine the mean time intervals between AGN outbursts in systems with multiple generations of X-ray cavities. We find that, like MS0735, their AGN rejuvenate on a time-scale that is approximately 1/3 of their mean central cooling time-scales, indicating that jet heating is outpacing cooling in these systems.

  9. Hydrodynamic models of AGN feedback in cooling core clusters

    NASA Astrophysics Data System (ADS)

    Vernaleo, John C.

    X-ray observations show that the Intra Cluster Medium (ICM) in many galaxy clusters is cooling at a rapid rate, often to the point that it should have radiated away all of its energy in less than the age of the cluster. There is however a very clear lack of enough cool end products of this gas in the centers of the clusters. Energetic arguments indicate that Active Galactic Nuclei (AGN) should be capable of heating the inner regions of clusters enough to offset the radiative cooling; truncating massive galaxy formation and solving the cooling flow problem. We present three sets of high resolution, ideal hydrodynamic simulations with the ZEUS code to test this AGN heating paradigm. For the first set of simulations, we study the dependence of the interaction between the AGN jets and the ICM on the parameters of the jets themselves. We present a parameter survey of two-dimensional (axisymmetric) models of back-to-back jets injected into a cluster atmosphere. We follow the passive evolution of the resulting structures. These simulations fall into roughly two classes, cocoon-bounded and non-cocoon bounded. We find that the cocoon-bounded sources inject significantly more entropy into the core regions of the ICM atmosphere, even though the efficiency with which the energy is thermalized is independent of the morphological class. In all cases, a large fraction of the energy injected by the jet ends up as gravitational potential energy due to the expansion of the atmosphere. For the second set, we present three-dimensional simulations of jetted AGN that act in response to cooling-mediated accretion of an ICM atmosphere. We find that our models are incapable of producing a long term balance of heating and cooling; catastrophic cooling can be delayed by the jet action but inevitably takes hold. At the heart of the failure of these models is the formation of a low density channel through which the jet can freely flow, carrying its energy out of the cooling core. Finally, we

  10. 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).

  11. Cooling, AGN Feedback and Star Formation in Cool-Core Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg; Ruszkowski, Mateusz

    2015-01-01

    The feedback from active galactic nuclei (AGNs) is widely considered to be the major heating source in cool-core galaxy clusters to prevent a classical cooling flow. Numerical simulations with AGN feedback have successfully suppressed radiative cooling, but generally fail to reproduce the right amount of cold gas and the expected cyclical AGN activities. We perform adaptive mesh simulations including both momentum-driven AGN feedback and star formation to study the interplay between cooling, AGN heating and star formation over ~ 6.5 Gyr time in an isolated cool-core cluster. Cold clumps first cool out of the ICM due to the non-liner perturbation driven by the AGN jets. These cold clumps feed both star formation and the supermassive black hole (SMBH), triggering an AGN outburst which increases the entropy of the ICM and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, which leads to a brief shutoff of the AGN. The ICM quickly cools and develops multiphase gas again, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. The average star formation rate is ~40 solar mass/yr. The black hole accretion rate shows a large scatter, but the average correlates well with the star formation rate and is roughly one order of magnitude lower.

  12. THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Cool, Richard J.; Eisenstein, Daniel J.; Kochanek, Christopher S.; Brown, Michael J. I.; Caldwell, Nelson; Forman, William R.; Hickox, Ryan C.; Jones, Christine; Murray, Stephen S.; Dey, Arjun; Jannuzi, Buell T.; Moustakas, John

    2012-03-20

    We present the galaxy optical luminosity function for the redshift range 0.05 < z < 0.75 from the AGN and Galaxy Evolution Survey, a spectroscopic survey of 7.6 deg{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z){sup (0.54{+-}0.64)} for red galaxies and (1 + z){sup (1.64{+-}0.39)} for blue galaxies.

  13. Characteristics of the optical variability of AGNs as a possible identification tool

    NASA Astrophysics Data System (ADS)

    Romelfanger, Alexander

    2016-01-01

    We present connections between broad categories of active galaxies and how their optical brightness varies with time. This could open new avenues for identifying active galactic nuclei, and observations could lend themselves to a deeper understanding of AGN structure. For this purpose, we obtain the CRTS light curves of the active galaxies in the Palomar Sample. These curves are then modeled with a CARMA (Continuous-Time Auto-Regressive Moving Average) process and transferred to the frequency domain. The characteristics of the variability are extracted from the power density spectrum. Finally, we search for correlations between active galaxies type (LINER, Seyfert Galaxy, Quasar, etc) and variability characteristics to test the use of our method as an identification tool.

  14. Morphological Properties and AGN Content of High Redshift Luminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Kartaltepe, Jeyhan S.; CANDELS Collaboration

    2013-01-01

    We explore the evolution of the morphological properties of (Ultra) Luminous Infrared Galaxies ((U)LIRGs) over cosmic time using a large sample of galaxies from Herschel observations of the CANDELS fields (including GOODS, COSMOS, and UDS). In particular, we investigate whether the role of galaxy mergers has changed between 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 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.

  15. AGN jets under the microscope: A divide? Doctoral Thesis Award Lecture 2011

    NASA Astrophysics Data System (ADS)

    Karouzos, M.; Britzen, S.; Witzel, A.; Zensus, A. J.; Eckart, A.

    2012-06-01

    A new paradigm for active galactic jet kinematics has emerged through detailed investigations of BL Lac objects using very long baseline radio interferometry. In this new scheme, most, if not all, jet components appear to remain stationary with respect to the core but show significant non-radial motions. This paper presents results from our kinematic investigation of the jets of a statistically complete sample of radio-loud flat-spectrum active galaxies, focusing on the comparison between the jet kinematic properties of BL Lacs and flat-spectrum radio-quasars. It is shown that there is a statistically significant difference between the kinematics of the two AGN classes, with BL Lacs showing more bent jets, that are wider and show slower movement along the jet axis, compared to flat-spectrum radio-quasars. This is interpreted as evidence for helically structured jets.

  16. Pan-STARRS1 variability of XMM-COSMOS AGN. II. Physical correlations and power spectrum analysis

    NASA Astrophysics Data System (ADS)

    Simm, T.; Salvato, M.; Saglia, R.; Ponti, G.; Lanzuisi, G.; Trakhtenbrot, B.; Nandra, K.; Bender, R.

    2016-01-01

    Aims: The goal of this work is to better understand the correlations between the rest-frame UV/optical variability amplitude of quasi-stellar objects (QSOs) and physical quantities such as redshift, luminosity, black hole mass, and Eddington ratio. Previous analyses of the same type found evidence for correlations between the variability amplitude and these active galactic nucleus (AGN) parameters. However, most of the relations exhibit considerable scatter, and the trends obtained by various authors are often contradictory. Moreover, the shape of the optical power spectral density (PSD) is currently available for only a handful of objects. Methods: We searched for scaling relations between the fundamental AGN parameters and rest-frame UV/optical variability properties for a sample of ~90 X-ray selected AGNs covering a wide redshift range from the XMM-COSMOS survey, with optical light curves in four bands (gP1, rP1, iP1, zP1) provided by the Pan-STARRS1 (PS1) Medium Deep Field 04 survey. To estimate the variability amplitude, we used the normalized excess variance (σ2rms) and probed variability on rest-frame timescales of several months and years by calculating σ2rms from different parts of our light curves. In addition, we derived the rest-frame optical PSD for our sources using continuous-time autoregressive moving average (CARMA) models. Results: We observe that the excess variance and the PSD amplitude are strongly anticorrelated with wavelength, bolometric luminosity, and Eddington ratio. There is no evidence for a dependency of the variability amplitude on black hole mass and redshift. These results suggest that the accretion rate is the fundamental physical quantity determining the rest-frame UV/optical variability amplitude of quasars on timescales of months and years. The optical PSD of all of our sources is consistent with a broken power law showing a characteristic bend at rest-frame timescales ranging between ~100 and ~300 days. The break timescale

  17. 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.

  18. Linking X-ray AGN with dark matter halos: a model compatible with AGN luminosity function and large-scale clustering properties

    NASA Astrophysics Data System (ADS)

    Hütsi, Gert; Gilfanov, Marat; Sunyaev, Rashid

    2014-01-01

    Aims: Our goal is to find a minimalistic model that describes the luminosity function and large-scale clustering bias of X-ray-selected active galactic nuclei in the general framework of the concordance ΛCDM model. Methods: We assume that a simple population-averaged scaling relation between the AGN X-ray luminosity LX and the host dark matter halo mass Mh exists. With such a relation, the AGN X-ray luminosity function can be computed from the halo mass function. Using the concordance ΛCDM halo mass function for the latter, we obtain the Mh - LX relation required to match the redshift-dependent AGN X-ray luminosity function known from X-ray observations. Results: We find that with a simple power-law-scaling Mh ∝ LΓ(z), our model can successfully reproduce the observed X-ray luminosity function. Furthermore, we automatically obtain predictions for the large-scale AGN clustering amplitudes and their dependence on the luminosity and redshift, which seem to be compatible with AGN clustering measurements. Our model also includes the redshift-dependent AGN duty cycle, which peaks at the redshift z ≃ 1, and its peak value is consistent with unity, suggesting that on average there is no more than one AGN per dark matter halo. For a typical X-ray-selected AGN at z ~ 1, our best-fit Mh - LX scaling implies low Eddington ratio LX/LEdd ~ 10-4 - 10-3 (2-10 keV band, no bolometric correction applied) and correspondingly high mass-growth e-folding times, suggesting that typical X-ray AGN are dominantly fueled via relatively inefficient "hot-halo" accretion mode.

  19. 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.

  20. 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 A.; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2016-02-01

    We address the relation between star formation and active galactic nucleus (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\\lt {10}22 {{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 star formation rate (SFR) of these galaxies is less than 0.1 M⊙ yr-1. They also tend to be radio faint (P\\lt {10}22 {{WHz}}-1). There is a nearly equal fraction of star-forming galaxies in radio faint (P\\lt {10}22 {{WHz}}-1) and radio bright galaxies (P≥slant {10}22 {{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 follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  1. Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe

    NASA Astrophysics Data System (ADS)

    Giallongo, E.; Grazian, A.; Fiore, F.; Fontana, A.; Pentericci, L.; Vanzella, E.; Dickinson, M.; Kocevski, D.; Castellano, M.; Cristiani, S.; Ferguson, H.; Finkelstein, S.; Grogin, N.; Hathi, N.; Koekemoer, A. M.; Newman, J. A.; Salvato, M.

    2015-06-01

    Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4-6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe. Aims: In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer, and various ground-based telescopes. Methods: We have adopted a relatively novel criterion. As a first step, high redshift galaxies are selected in the NIR H band down to very faint levels (H ≤ 27) using reliable photometric redshifts. At z> 4 this corresponds to a selection criterion based on the galaxy rest-frame UV flux. AGN candidates are then picked up from this parent sample if they show X-ray fluxes above a threshold of FX ˜ 1.5 × 10-17 erg cm-2 s-1 (0.5-2 keV), corresponding to a probability of spurious detections of 2 × 10-4 in the deep X-ray 4 Ms Chandra image. Results: We have found 22 AGN candidates at z> 4 and we have derived the first estimate of the UV luminosity function in the redshift interval 4 AGN host galaxies. Both effects could, in principle, significantly reduce the estimated average volume densities and/or ionizing emissivities, especially at the highest

  2. The stellar content of low luminosity AGN

    NASA Astrophysics Data System (ADS)

    Cid Fernandes, R.; Gonzalez-Delgado, R.; Schmitt, H.; Storchi-Bergmann, T.; Martins, L. P.

    2003-08-01

    We present a spectroscopic study of the stellar populations of LINERs and LINER/HII Transition Objects (TOs). Our main goal is to determine whether the stars who live in the innermost regions of these low luminosity active galaxies are in some way related to their emission line properties, which would imply in a link between the stellar population and the gas excitation mechanism. High sinal to noise long-slit spectra in the 3500-5400 Å interval were collected for over 50 galaxies. The sample was selected out of the magnitude limited survey of ~ 500 galaxies of Ho et al (1997), which provides a representative sample of the local universe. The stellar content of these galaxies was examined in entirely empirical terms, both by the measurement of colors and absorption features and by a comparison with non-active galaxies spanning a wide range of stellar populations, from young starbursts to old elliptical galaxies. Our main findings are: No features due to Wolf-Rayet stars were detected in either LINERs or TOs. On the other hand, strong High order Balmer lines (HOBLs) of HI in absorption are ubiquitous in TOs but not in LINERs. About 50% of the TOs exihibit these features, which indicate the presence of 108-109 yr populations. These TOs also have diluted metal absorption lines and somewhat bluer colors than other objects in the sample. Most LINERs and the remaining 50% TOs, on the other hand, have deep metal lines typical of old stellar populations. The presence of intermediate age populations anti-correlates strongly with [OI]/Ha, a critical diagnostic line ratio. For instance, over 90% of nuclei with conspicuous intermediate age populations are weak [OI]-emitters. These findings strongly suggest a link between the stellar populations and the ionization mechanism in TOs. Possible scenarios, including weak circumnuclear starbursts, supernova-remnannts and evolved post-starburst populations, are being examined. By analogy with previous work on starburst + Seyfert 2

  3. The Distribution and Kinematics of Cold Near-Nuclear Gas in AGN

    NASA Astrophysics Data System (ADS)

    Gallimore, J.

    1993-12-01

    The kinematics and distribution of near nuclear cold gas in AGN is essentially unknown, in large part because the low emissivity of this gas precludes direct measurement. We have initiated a program to determine the kinematics and spatial distribution of cold nuclear gas in AGN using the technique of synthesis mapping of HI (and OH) in absorption against a spatially resolved radio continuum source. These measurements will allow us to address a number of key astrophysical questions; (1) What are the masses of the `central engines' in Seyfert galaxies, (2) Is there evidence for infalling neutral matter which could fuel the activity and if so, can we trace that inflow from the hundreds of parsec scale inward?, (3) How is the pc scale ionised and neutral gas related in Seyferts?, (4) Can we find evidence for `tori' of cold obscuring matter in Seyfert 2s, as predicted by the unified schemes? We have recently completed HI VLA A array absorption studies of 12 Seyfert galaxies. We have obtained followup Merlin observations for NGC 1068 and NGC 3079. In NGC 1068 we have determined unambiguously the orientation of the linear radio structure; namely the NE lobe is pointed towards us. We have found supportive evidence for an AGN-driven outflow at the SW jet. We also find a kinematic disturbance and optical depth enhancement in the HI in the inner disk which suggests we are witnessing a bar-driven shock. In NGC 3079, the absorption profile is too broad to be explained by disk gas but must instead arise primarily in rapidly moving clouds located near the radio source. Slightly resolved, blue and redshifted absorption lines may be due to a ring of cold gas with a radius of ~ 90 parsecs. The mass interior to this postulated ring is >10(8) solar masses, implying an extremely dense stellar core or a compact central object. We report here on the preliminary results for the sample as a whole, and on the more detailed results for NGC3079 and NGC 1068.

  4. 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.

  5. 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

  6. The AGN Contribution to Galaxy Merger Infrared Luminosities

    NASA Astrophysics Data System (ADS)

    Rosenthal, Lee; Hayward, Christopher C.; Smith, Howard; Ashby, Matthew; Hung, Chao-Ling; Martinez-Galarza, Rafael; Weiner, Aaron; Zezas, Andreas; Lanz, Lauranne

    2015-01-01

    We investigate the contribution of AGN activity to the infrared luminosity of interacting galaxies by analyzing dust radiative transfer calculations of a hydrodynamically simulated merger, created with the code GADGET-2. We focus on emission in the mid-IR to far-IR wavelength ranges, and trace the luminosity density of an interacting gas-rich galaxy pair throughout its evolution. We find that the AGN contribution to IR luminosity is greatest during and immediately after coalescence of the galaxies' central black holes. This period lasts roughly 80 Myr, during which time the increased influx of gas to the center of the merger increases the total luminosity by a factor of a thousand or more due to both increased star formation rate (SFR) and black hole accretion. We compare different interstellar medium models used to describe sub-resolution gas and dust clouds in the radiative transfer calculations by studying the color evolution of our merger in the Herschel Space Observatory photometric filter bands, and compare the results to Herschel observations. We conclude that using infrared luminosity as a simple surrogate for SFR can overestimate the true rate, due to the contribution of AGN or other dust heating mechanisms. This conclusion has an especially significant impact in assessing the star formation activity in high-redshift galaxies for which luminosity (the best measured property) may not accurately measure the SFR, and in cases where the molecular gas content can differ from that of local systems. Further work will extend this analysis to simulations of mergers between late-type galaxies. This work was supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851, by the Smithsonian Institution and by NASA grant NNX14AJ6IG.

  7. AGN-stimulated cooling of hot gas in elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Valentini, Milena; Brighenti, Fabrizio

    2015-04-01

    We study the impact of relatively weak active galactic nucleus (AGN) feedback on the interstellar medium (ISM) of intermediate and massive elliptical galaxies. We find that the AGN activity, while globally heating the ISM, naturally stimulates some degree of hot gas cooling on scales of several kpc. This process generates the persistent presence of a cold ISM phase, with mass ranging between 104 and ≳ 5 × 107 M⊙, where the latter value is appropriate for group centred, massive galaxies. Widespread cooling occurs where the ratio of cooling to free-fall time before the activation of the AGN feedback satisfies tcool/tff ≲ 70, that is we find a less restrictive threshold than commonly quoted in the literature. This process helps explaining the body of observations of cold gas (both ionized and neutral/molecular) in Ellipticals and, perhaps, the residual star formation detected in many early-type galaxies. The amount and distribution of the off-centre cold gas vary irregularly with time. The cold ISM velocity field is irregular, initially sharing the (outflowing) turbulent hot gas motion. Typical velocity dispersions of the cold gas lie in the range 100-200 km s-1. Freshly generated cold gas often forms a cold outflow and can appear kinematically misaligned with respect to the stars. We also follow the dust evolution in the hot and cold gas. We find that the internally generated cold ISM has a very low dust content, with representative values of the dust-to-gas ratio of 10-4-10-5. Therefore, this cold gas can escape detection in the traditional dust-absorption maps.

  8. 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.

  9. Liners and Low Luminosity AGN in the ROSAT Database

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; West, Donald K. (Technical Monitor)

    2003-01-01

    This program has led to a series of papers being written and published in the Astrophysical Journal. Together these papers try to explain major parts of the LINER and low luminosity AGN puzzle. One paper ('Accretion Disk Instabilities, Cold Dark Matter Models, and Their Role in Quasar Evolution', Hatziminaoglou E., Siemiginowska A., & Elvis M., 2001, ApJ, 547, 90) describes an analytical model for the evolution of the quasar luminosity function. By combining the Press-Schechter formalism for the masses of initial structures with the luminosity distribution for a population of single mass black holes given by an unstable accretion disk an almost complete end-to-end physics-based model of quasar evolution is produced. In this model black holes spend 75% of their time in a low accretion state (at L(Edd)). This low state population of black holes is likely to be observed as the LINER and low luminosity AGNs in the local universe. Another paper ('Broad Emission Line Regions in AGN: the Link with the Accretion Power', Nicastro F., 2000, ApJ Letters, 530, L65) gives a physical basis for why low state black holes appear as LINERS. By linking the Lightman-Eardley instability in an accretion disk to the ori.gin of a wind that contains the broad emission line cloud material this model explains the large widths seen in these lines as being the Keplerian velocity of the disk at the instability radius. For LINERS the key is that below an accretion rate of 10(exp -3)M(sub Edd)the Lightman-Eardley instability falls within the innermost stable orbit of the disk, and so leaves the entire disk stable. No wind occurs, and so no broad emission lines are seen. Most LINERS are likely to be black holes in this low state. Tests of this model are being considered.

  10. Fossil AGN jets as ultrahigh-energy particle accelerators

    NASA Astrophysics Data System (ADS)

    Benford, Gregory; Protheroe, R. J.

    2008-01-01

    Remnants of active galactic nucleus (AGN) jets and their surrounding cocoons leave colossal magnetohydrodynamic (MHD) fossil structures storing total energies ~1060 erg. The original AGN may be dead but the fossil will retain its stable configuration resembling the reversed-field pinch (RFP) encountered in laboratory MHD experiments. In an RFP the longitudinal magnetic field changes direction at a critical distance from the axis, leading to magnetic reconnection there, and to slow decay of the large-scale RFP field. We show that this field decay induces large-scale electric fields which can accelerate cosmic rays with an E-2 power law up to ultrahigh energies with a cut-off depending on the fossil parameters. The cut-off is expected to be rigidity dependent, implying the observed composition would change from light to heavy close to the cut-off if one or two nearby AGN fossils dominate. Given that several per cent of the Universe's volume may house such slowly decaying structures, these fossils may even re-energize ultrahigh-energy cosmic rays from distant/old sources, offsetting the `GZK-losses' due to interactions with photons of the cosmic microwave background radiation and giving evidence of otherwise undetectable fossils. In this case the composition would remain light to the highest energies if distant sources or fossils dominated, but otherwise would be mixed. It is hoped the new generation of cosmic ray experiments such as the Pierre Auger Observatory and ultrahigh-energy neutrino telescopes such as ANITA and lunar Cherenkov experiments will clarify this.

  11. Why are AGN found in high-mass galaxies?

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Kauffmann, Guinevere

    2008-12-01

    There is a strong observed mass dependence of the fraction of nearby galaxies that contain either low-luminosity [low-ionization nuclear emission-line region (LINER) type] or higher luminosity (Seyfert or composite type) active galactic nuclei (AGN). This implies that either only a small fraction of low-mass galaxies contain black holes, or that the black holes in these systems only accrete rarely or at very low rates, and hence are generally not detectable as AGN. In this paper, we use semi-analytic models implemented in the Millennium Simulation to analyse the mass dependence of the merging histories of dark matter haloes and of the galaxies that reside in them. Only a few per cent of galaxies with stellar masses less than M* < 1010Msolar are predicted to have experienced a major merger. The fraction of galaxies that have experienced major mergers increases steeply at larger stellar masses. We argue that if a major merger is required to form the initial seed black hole, the mass dependence of AGN activity in local galaxies can be understood quite naturally. We then investigate when the major mergers that first create these black holes are predicted to occur. High-mass galaxies are predicted to have formed their first black holes at very early epochs. The majority of low-mass galaxies never experience a major merger and hence may not contain a black hole, but a significant fraction of the supermassive black holes that do exist in low-mass galaxies are predicted to have formed recently.

  12. Revisiting Stochastic Variability of AGNs with Structure Functions

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-08-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to the expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs), have triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ∼9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the “subensemble” SFs in the redshift–absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power law (SPL; in the “red noise regime” after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at γ =0.55+/- 0.08 (0.52 ± 0.06) and is consistent with the DRW model. There is a hint of a weak correlation of γ with the luminosity and a lack of correlation with the black hole mass. The typical decorrelation timescale in the optical is τ =0.97+/- 0.46 year. The SF amplitude at one year obtained from the SPL fitting is {{SF}}0=0.22+/- 0.06 mag and is overestimated because the SF is already at the turnover part, so the true value is {{SF}}0=0.20+/- 0.06 mag. The asymptotic variability is {{SF}}∞ =0.25+/- 0.06 mag. It is strongly anticorrelated with both the luminosity and the Eddington ratio and is correlated with the black hole mass. The reliability of these results is fortified with Monte Carlo simulations.

  13. 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.

  14. Agnes Mary Clerke and the Rise of Astrophysics

    NASA Astrophysics Data System (ADS)

    Brück, M. T.

    2008-03-01

    Acknowledgements; Introduction; 1. Family background in County Cork; 2. Ireland and Italy; 3. London, the literary scene; 4. The History of Astronomy; 5. A circle of astronomers; 6. A visit to South Africa; 7. The System of the Stars; 8. Social life in scientific circles; 9. Homer, the Herschels and a revised History; 10. The opinion moulder; 11. Popularisation, cryogenics and evolution; 12. Problems in Astrophysics; 13. Women in astronomy in Britain in Agnes Clerke's time; 14. Revised System of the Stars; 15. Cosmogonies, cosmology and Nature's spiritual clues; 16. Last days and retrospect; 17. Epilogue; Notes; Appendix; Bibliography; Index.

  15. Hard X-ray AGN Clustering & SMBH Growth

    NASA Astrophysics Data System (ADS)

    Cappelluti, Nico

    2012-09-01

    In this review talk I present the status of the art of the studies on AGN clustering in the X-ray band and its applications in understanding the coeval growth of SMBH and Dark Matter Halos. A well defined picture has been taken up to z~2 while, at high-z, where important physical phenomena connected with SMBH formation, the knowledge is still relegated to the study of anisotropies of the unresolved CXB. I will finally present recent applications of clustering analysis to the study of clustering pattern in the unresolved CXB, and pointing out the possibility of the detection of the first BH in the University through fluctuation analysis.

  16. Dust in the torus of the AGN unified model

    NASA Astrophysics Data System (ADS)

    Mason, Rachel E.

    2015-10-01

    In these proceedings I briefly summarize our current understanding of the dusty torus of the AGN unified model: its structure, composition, and ideas about its origin and evolution. The paper is based on an invited review talk at the 7th Meeting on Cosmic Dust, which covered dust-related topics in areas from comets to debris disks and high-redshift galaxies. This is therefore intended to be an accessible, introductory overview of the torus with some emphasis on the solid-state spectral features observed.

  17. Effects of AGN feedback on ΛCDM galaxies

    NASA Astrophysics Data System (ADS)

    Lagos, Claudia Del P.; Cora, Sofía A.; Padilla, Nelson D.

    2008-08-01

    We study the effects of active galactic nuclei (AGN) feedback on the formation and evolution of galaxies by using a combination of a cosmological N-body simulation of the concordance Lambda cold dark matter (ΛCDM) paradigm and a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other BHs, (ii) accretion during starbursts triggered by disc instabilities and (iii) accretion of gas cooled from quasi-hydrostatic hot gas haloes. It is assumed that feedback from AGN operates in the last case. The model has been calibrated in order to reproduce observational correlations between BH mass and mass, velocity dispersion and absolute magnitudes of the galaxy bulge. AGN feedback has a strong impact on reducing or even suppressing gas cooling, an effect that becomes important at lower redshifts. This phenomenon helps to reproduce the observed galaxy luminosity function (LF) in the optical and near-infrared bands at z = 0, and the cosmic star formation rate and stellar mass functions over a wide redshift range (0 <~ z <~ 5). It also allows us to have a population of massive galaxies already in place at z >~ 1, which are mostly early-type and have older and redder stellar populations than lower mass galaxies, reproducing the observed bimodality in the galaxy colour distribution, and the morphological fractions. The evolution of the optical QSO LF is also reproduced, provided that the presence of a significant fraction of obscured QSOs is assumed. We explore the effects of AGN feedback during starbursts finding that, in order to obtain a good agreement with observations, these need to be strong enough to expel the reheated gas away from the galaxy halo. We also test new, recent prescriptions for dynamical friction time-scales, and find that they produce an earlier formation of elliptical

  18. AGNs with composite spectra. II. Additional data

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. C.; Véron-Cetty, M.-P.; Véron, P.

    1999-03-01

    In a previous paper \\cite[(Véron et al. 1997)]{ver97} we presented medium resolution (3.4 Angstroms FWHM) spectroscopic observations of 15 ``transition objects'', selected for having an ambiguous location in the \\cite[Veilleux & Osterbrock (1987)]{vei87} diagnostic diagrams, and showed that most of them were in fact ``composite'', this being due to the simultaneous presence on the slit of both a Seyfert or Liner nucleus and a H Ii region. Here, we report new spectroscopic observations of 53 emission-line galaxies with a ``transition'' spectrum, bringing up to 61 the total number of observed objects in an unbiased sample of 88 ``transition objects''. Almost all of the observed galaxies have a ``composite" nature, confirming the finding that true ``transition'' spectra may not exist at all. By eliminating ``composite objects'' from the diagnostic diagrams, a clear separation between the different classes of nuclear emission-line regions (Seyfert 2s, Liners and H Ii regions) becomes apparent; by restricting the volume occupied by the different line-emitting regions in the 3-dimensional diagnostic diagrams, we are also restricting the range of possible physical parameters in these regions. There seems to be no continuity between Seyfert 2s and Liners, the two classes occupying distinct volumes in the 3-dimensional space defined by lambda 6300/Hα ii, lambda 6583/Hα , and lambda 6300/Hα . Based on observations collected at the Observatoire de Haute-Provence (CNRS), France, and Hubble Space Telescope (HST) data obtained from the Space Telescope European Coordinating Facility (ST-ECF) archive. Tables 5 and 6 are 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/Abstract.html

  19. The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN

    NASA Astrophysics Data System (ADS)

    Pozzi, F.; Vignali, C.; Comastri, A.; Bellocchi, E.; Fritz, J.; Gruppioni, C.; Mignoli, M.; Maiolino, R.; Pozzetti, L.; Brusa, M.; Fiore, F.; Zamorani, G.

    2010-07-01

    Aims: We combine near-to-mid-IR Spitzer data with shorter wavelength observations (optical to X-rays) to get insight into the properties of a sample of luminous, obscured active galactic nuclei (AGN). We aim at modelling their broad-band spectral energy distributions (SEDs) in order to estimate the main parameters related to the dusty torus that is assumed to be responsible for the reprocessed IR emission. Our final goal is to estimate the intrinsic nuclear luminosities and the Eddington ratios for our luminous, obscured AGN. Methods: The sample comprises 16 obscured high-redshift (0.9 ⪉ z ⪉ 2.1), X-ray luminous quasars (L2-10 keV ~ 1044 erg s-1) selected from the HELLAS2XMM survey in the 2-10 keV band. The optical-IR SEDs are described by a multi-component model that includes a stellar component to account for the optical and near-IR emission, an AGN component that dominates in the mid-IR (mainly emission from a dusty torus heated by nuclear radiation), and a starburst to reproduce the far-IR bump. A radiative transfer code to compute the spectrum and intensity of dust reprocessed emission was extensively tested against our multiwavelength data. While the torus parameters and the BH accretion luminosities are a direct output of the SED-fitting procedure, the BH masses were estimated indirectly by means of the local Mbulge-MBH relation. Results: The majority (~80%) of the sources show moderate optical depth (τ9.7 µm ≤ 3), and the derived column densities NH are consistent with the X-ray inferred values (1022 ⪉ NH ⪉ 3 × 1023 cm-2) for most of the objects, confirming that the sources are moderately obscured Compton-thin AGN. Accretion luminosities in the range 5 × 1044 ⪉ Lbol ⪉ 4 × 1046 erg s-1 are inferred from the multiwavelength fitting procedure. We compare model luminosities with those obtained by integrating the observed SED, finding that the latter are lower by a factor of ~2 in the median. The discrepancy can be as high as an order of

  20. The Connections Between the UV and Optical Fe ii Emission Lines in Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Kovačević-Dojčinović, Jelena; Popović, Luka Č.

    2015-12-01

    We investigate the spectral properties of the UV (λλ2650-3050 Å) and optical (λλ4000-5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe iiopt) versus EW [O iii] 5007 Å and EW Fe iiopt versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  1. X-ray evidence for ultra-fast outflows in AGNs

    NASA Astrophysics Data System (ADS)

    Tombesi, Francesco; Sambruna, Rita; Braito, Valentina; Reeves, James; Reynolds, Christopher; Cappi, Massimo

    2012-07-01

    X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts and 5 radio galaxies observed with XMM-Newton and Suzaku. We assessed the global detection significance of the absorption lines and performed a detailed photo-ionization modeling. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1} and the associated mechanical power is high, in the range ˜10^{43}--10^{45} erg/s. Therefore, UFOs are capable to provide a significant contribution to the AGN cosmological feedback and their study can provide important clues on the connection between accretion disks, winds and jets.

  2. AGN proximity zone fossils and the delayed recombination of metal lines

    NASA Astrophysics Data System (ADS)

    Oppenheimer, Benjamin D.; Schaye, Joop

    2013-09-01

    We model the time-dependent evolution of metal-enriched intergalactic and circumgalactic gas exposed to the fluctuating radiation field from an active galactic nucleus (AGN). We consider diffuse gas densities (nH = 10-5-10-2.5 cm-3) exposed to the extra-galactic background (EGB) and initially in thermal equilibrium (T ˜ 104-104.5 K). Once the proximate AGN field turns on, additional photo-ionization rapidly ionizes the HI and metals. The enhanced AGN radiation field turns off after a typical AGN lifetime (τAGN = 1-20 Myr) and the field returns to the EGB intensity, but the metals remain out of ionization equilibrium for time scales that can significantly exceed τAGN. We define this phase as the AGN proximity zone `fossil' phase and show that high ionization stages (e.g. OVI, NeVIII, MgX) are in general enhanced, while the abundances of low ions (e.g. CIV, OIV, MgII) are reduced. In contrast, HI re-equilibrates rapidly (≪τAGN) owing to its low neutral fraction at diffuse densities. We demonstrate that metal column densities of intervening gas observed in absorption in quasar sight lines are significantly affected by delayed recombination for a wide range of densities, metallicities, AGN strengths, AGN lifetimes and AGN duty cycles. As an example, we show that a fossil zone model can simultaneously reproduce the observed NeVIII, MgII, HI and other metal columns of the z = 0.927 PG1206+259 absorption system observed by Tripp et al. using a single, T ˜ 104 K phase model. At low redshift even moderate-strength AGN that are off for 90 per cent of the time could significantly enhance the high-ion metal columns in the circum-galactic media of galaxies observed without active AGN. Fossil proximity zones may be particularly important during the quasar era, z ˜ 2-5. Indeed, we demonstrate that at these redshifts a large fraction of the metal-enriched intergalactic medium may consist of out-of-equilibrium fossil zones. AGN proximity zone fossils allow a whole new class

  3. Optically Elusive AGN in the 3XMM Catalog and the Chandra-COSMOS field

    NASA Astrophysics Data System (ADS)

    Pons, Estelle; Watson, Mike; Elvis, Martin; Civano, Francesca M.

    2015-01-01

    'Optically elusive AGN' are powerful X-ray sources (LHX > 1042 erg/s), but are not detected as AGN in the optical. Pons and Watson (2014) showed that in XMM these AGNs are a mix of Narrow Line Seyfert 1s, True Seyfert 2's and weak Seyfert 2s. The nature of these objects, coming from the cross-match of 3XMM with the SDSS-DR9 spectroscopic catalog, has been investigated through a detailed analysis of their IR/optical and X-ray properties. The fainter Chandra-COSMOS field should be rich in optically elusive AGNs as ¾ of the AGNs there are narrow-lined. There are ~850 Chandra-COSMOS galaxy spectra, mainly from five different telescopes (SDSS, Magellan, MMT, VLT and Keck). To find optically elusive objects, we investigate the optical classification using emission line diagnostic diagrams. For low redshift galaxies (z~<0.7) the standard BPT diagram ([OIII

  4. Stellar and quasar feedback in concert: effects on AGN accretion, obscuration, and outflows

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Torrey, Paul; Faucher-Giguère, Claude-André; Quataert, Eliot; Murray, Norman

    2016-05-01

    We study the interaction of feedback from active galactic nuclei (AGN) and a multiphase interstellar medium (ISM), in simulations including explicit stellar feedback, multiphase cooling, accretion-disc winds, and Compton heating. We examine radii ˜0.1-100 pc around a black hole (BH), where the accretion rate on to the BH is determined and where AGN-powered winds and radiation couple to the ISM. We conclude: (1) the BH accretion rate is determined by exchange of angular momentum between gas and stars in gravitational instabilities. This produces accretion rates ˜0.03-1 M⊙ yr-1, sufficient to power luminous AGN. (2) The gas disc in the galactic nucleus undergoes an initial burst of star formation followed by several million years where stellar feedback suppresses the star formation rate (SFR). (3) AGN winds injected at small radii with momentum fluxes ˜LAGN/c couple efficiently to the ISM and have dramatic effects on ISM properties within ˜100 pc. AGN winds suppress the nuclear SFR by factors ˜10-30 and BH accretion rate by factors ˜3-30. They increase the outflow rate from the nucleus by factors ˜10, consistent with observational evidence for galaxy-scale AGN-driven outflows. (4) With AGN feedback, the predicted column density distribution to the BH is consistent with observations. Absent AGN feedback, the BH is isotropically obscured and there are not enough optically thin sightlines to explain type-I AGN. A `torus-like' geometry arises self-consistently as AGN feedback evacuates gas in polar regions.

  5. THE LICK AGN MONITORING PROJECT: BROAD-LINE REGION RADII AND BLACK HOLE MASSES FROM REVERBERATION MAPPING OF Hbeta

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Baliber, Nairn; Bennert, Vardha Nicola; Greene, Jenny E.; Hidas, Marton G.; Canalizo, Gabriela; Hiner, Kyle D.; Filippenko, Alexei V.; Ganeshalingam, Mohan; Lee, Nicholas; Li, Weidong; Serduke, Frank J. D.; Silverman, Jeffrey M.; Steele, Thea N.; Gates, Elinor L.; Malkan, Matthew A.; Minezaki, Takeo; Sakata, Yu

    2009-11-01

    We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range approx10{sup 6}-10{sup 7} M {sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad Hbeta emission. We present here the light curves for all the objects in this sample and the subsequent Hbeta time lags for the nine objects where these measurements were possible. The Hbeta lag time is directly related to the size of the broad-line region (BLR) in AGNs, and by combining the Hbeta lag time with the measured width of the Hbeta emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local M {sub BH}-sigma{sub *}relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hbeta line profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting BLR clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on the physical models of the BLR by the velocity-resolved response

  6. Simulations of the OzDES AGN reverberation mapping project

    NASA Astrophysics Data System (ADS)

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; Banerji, Manda; McMahon, Richard; Sharp, Rob; Lidman, C.

    2015-10-01

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ≥500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius-luminosity (R-L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ˜35-45 per cent of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ˜1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R-L relationship parameters for H β, Mg II λ2798, and C IV λ1549. Extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R-L parameter constraints for all broad emission lines.

  7. An AGN Identification for 3EG J2006-2321

    NASA Technical Reports Server (NTRS)

    Wallace, P. M.; Halpern, J. P.; Magalhaes, A. M.; Thompson, D. J.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321 (l = 18 deg.82, b = -26 deg.26). The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of archived radio data indicate that its most probable identification is with PMN J2005-2310, a flat-spectrum radio quasar with a 5GHz flux density of 260 mJy. Study of the V = 19.3 optical counterpart indicates a redshift of 0.833 and variable linear polarization. No X-ray source has been detected near the position of PMN J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper limit provides for a spectral energy distribution with global characteristics similar to those of known gamma-ray blazars. Taken together, these data indicate that 3EG J2006-2321, listed as unidentified in the 3rd EGRET Catalog, is a member of the blazar class of AGN. The 5-GHz radio flux density of this blazar is the lowest of the 68 EGRET-detected AGN. The fact that EGRET has detected such a source has implications for unidentified EGRET sources, particularly those at high latitudes (absolute value of b greater than 30 deg), many of which may be blazars.

  8. Hot Gas and AGN Feedback in Galaxies and Nearby Groups

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Forman, William; Bogdan, Akos; Randall, Scott; Kraft, Ralph; Churazov, Eugene

    2013-07-01

    Massive galaxies harbor a supermassive black hole at their centers. At high redshifts, these galaxies experienced a very active quasar phase, when, as their black holes grew by accretion, they produced enormous amounts of energy. At the present epoch, these black holes still undergo occasional outbursts, although the mode of their energy release is primarily mechanical rather than radiative. The energy from these outbursts can reheat the cooling gas in the galaxy cores and maintain the red and dead nature of the early-type galaxies. These outbursts also can have dramatic effects on the galaxy-scale hot coronae found in the more massive galaxies. We describe research in three areas related to the hot gas around galaxies and their supermassive black holes. First we present examples of galaxies with AGN outbursts that have been studied in detail. Second, we show that X-ray emitting low-luminosity AGN are present in 80% of the galaxies studied. Third, we discuss the first examples of extensive hot gas and dark matter halos in optically faint galaxies.

  9. XMM-Newton, powerful AGN winds and galaxy feedback

    NASA Astrophysics Data System (ADS)

    Pounds, K.; King, A.

    2016-06-01

    The discovery that ultra-fast ionized winds - sufficiently powerful to disrupt growth of the host galaxy - are a common feature of luminous AGN is major scientific breakthrough led by XMM-Newton. An extended observation in 2014 of the prototype UFO, PG1211+143, has revealed an unusually complex outflow, with distinct and persisting velocities detected in both hard and soft X-ray spectra. While the general properties of UFOs are consistent with being launched - at the local escape velocity - from the inner disc where the accretion rate is modestly super-Eddington (King and Pounds, Ann Rev Astron Astro- phys 2015), these more complex flows have raised questions about the outflow geometry and the importance of shocks and enhanced cooling. XMM-Newton seems likely to remain the best Observatory to study UFOs prior to Athena, and further extended observations, of PG1211+143 and other bright AGN, have the exciting potential to establish the typical wind dynamics, while providing new insights on the accretion geometry and continuum source structure. An emphasis on such large, coordinated observing programmes with XMM-Newton over the next decade will continue the successful philosophy pioneered by EXOSAT, while helping to inform the optimum planning for Athena

  10. Simulations of the OzDES AGN reverberation mapping project

    SciTech Connect

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; Banerji, Manda; McMahon, Richard; Sharp, Rob; Lidman, C.

    2015-08-26

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ~500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ~35–45 % of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ~1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for Hβ, MgIIλ2798, and C IVλ1549. As a result, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.

  11. 'Harder when Brighter' Spectral Variability in Low-Luminosity AGN

    NASA Astrophysics Data System (ADS)

    Connolly, S.; McHardy, I.; Skipper, C.; Dwelly, T.

    2015-07-01

    We present X-ray spectral variability of four low accretion rate AGN - M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the `softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely main source of spectral variability is found to be luminosity-dependent changes in the photon index of the power law component. An anticorrelation between the photon index and the count rate is found in all of the sources. The anticorrelation is likely to be caused by accretion via a radiatively-inefficient accretion flow, expected in low-Eddington ratio systems such as these, and/or due to the presence of a jet. This behaviour is similar to that seen in the `hard state' of X-ray binaries, implying that these LLAGN are in a similar state.

  12. Effects of AGN feedback in galaxy groups and Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Lagos, C.; Padilla, N.; Cora, S.

    2009-05-01

    The combination of Cosmological numerical simulations and semi-analytical models of galaxy formation is a very appropriate method to study how different phenomena influence the galaxy and galaxy cluster formation. The main advantage of this combination consists in the fact that N-body simulations do not need to be rerun every time a change in the assumptions