HOST GALAXY PROPERTIES OF THE<i>SWIFT</i>BAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

Koss, Michael; Mushotzky, R. F.; Veilleux, Sylvain; Winter, L. M.; Baumgartner, W. H.; Tueller, J.; Gehrels, N.; Valencic, Lynne

doi:10.1088/0004-637x/739/2/57

Cited by 147 publications

(210 citation statements)

References 68 publications

(95 reference statements)

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“…Although the source numbers are currently small, the above implies a relatively high fraction (50%±33%) of close to edge-on systems for CT AGNs selected by NuSTAR. For comparison, only ≈16% of the general hard-X-rayselected AGN population have < b a 0.3, based on isophotal analyses for the SwiftBAT AGN sample (Koss et al 2011). Although the difference is only weakly significant, a similar result has also been reported for CT AGNs selected with SwiftBAT (Koss et al 2016a).…”

Section: Host Galaxiesmentioning

confidence: 54%

The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at >10 keV

Lansbury

Alexander

Aird

et al. 2017

ApJ

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We identify sources with extremely hard X-ray spectra (i.e., with photon indices of  G 0.6) in the 13deg 2 NuSTAR serendipitous survey, to search for the most highly obscured active galactic nuclei (AGNs) detected at >10 keV. Eight extreme NuSTAR sources are identified, and we use the NuSTAR data in combination with lower-energy X-ray observations (from Chandra, SwiftXRT, and XMM-Newton) to characterize the broadband (0.5-24 keV) X-ray spectra. We find that all of the extreme sources are highly obscured AGNs, including three robust Compton-thick (CT; >Ń 1.5 10 H 24 cm −2 ) AGNs at low redshift ( < z 0.1) and a likely CT AGN at higher redshift (z = 0.16). Most of the extreme sources would not have been identified as highly obscured based on the low-energy (<10 keV) X-ray coverage alone. The multiwavelength properties (e.g., optical spectra and X-ray-mid-IR luminosity ratios) provide further support for the eight sources being significantly obscured. Correcting for absorption, the intrinsic rest-frame 10-40keV luminosities of the extreme sources cover a broad range, from »5 10 42 to 10 45 erg s −1 . The estimated number counts of CT AGNs in the NuSTAR serendipitous survey are in broad agreement with model expectations based on previous X-ray surveys, except for the lowest redshifts ( < z 0.07), where we measure a high CT fraction of16 . For the small sample of CT AGNs, we find a high fraction of galaxy major mergers (50% ± 33%) compared to control samples of "normal" AGNs.

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Section: Host Galaxiesmentioning

confidence: 54%

The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at >10 keV

Lansbury

Alexander

Aird

et al. 2017

ApJ

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“…Between these two populations lies the transition zone, the 'green valley' (Bell et al 2004;Martin et al 2007;Fang et al 2012;Schawinski et al 2014). Previous work has shown that X-ray selected AGN are found in galaxies that show signs of star formation, so either in the blue cloud or the green valley (Silverman et al 2009;Treister et al 2009;Koss et al 2011;Schawinski et al 2009;Hickox et al 2009;Rosario et al 2013;Goulding et al 2014). For our simple model we assume that most of the Xray selected AGN are hosted by blue and green galaxies and use the stellar mass function of these galaxies as input when constraining the ERDF relative to the XLF.…”

Section: Two Accretion Modesmentioning

confidence: 99%

“…These sources would have to be taken into account in future work once the data is available. The X-ray selection of AGN has been found to often select galaxies that are bluer in color than mass matched inactive galaxies and optically selected Seyferts (Koss et al 2011).…”

Section: Agn Luminosity Functionsmentioning

confidence: 99%

“…• host galaxies: As we discussed above, X-ray selected AGN tend to be found in optically blue and green galaxies, whereas radio selected AGN are often hosted by optically red galaxies (Silverman et al 2009;Smolčić 2009;Treister et al 2009;Smolčić et al 2009;Koss et al 2011;Schawinski et al 2009;Hickox et al 2009;Janssen et al 2012;Rosario et al 2013;Goulding et al 2014;Ching et al 2017). Star forming and quiescent galaxies are thought to be accreting in the cold and hot phases (Shabala et al 2008).…”

Section: The Physical Interpretation Of Two Mass Independent Erdfsmentioning

confidence: 99%

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AGNs and Their Host Galaxies in the Local Universe: Two Mass-independent Eddington Ratio Distribution Functions Characterize Black Hole Growth

Weigel

Schawinski

Čaplar

et al. 2017

ApJ

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We use a phenomenological model to show that black hole growth in the local Universe (z 0.1) can be described by two separate, mass independent Eddington ratio distribution functions (ERDFs). We assume that black holes can be divided into two independent groups: those with radiatively efficient accretion, primarily hosted by optically blue and green galaxies, and those with radiatively inefficient accretion, which are mainly found in red galaxies. With observed galaxy stellar mass functions as input, we show that the observed AGN luminosity functions can be reproduced by using mass independent, broken power law shaped ERDFs. We use the observed hard X-ray and 1.4 GHz radio luminosity functions to constrain the ERDF for radiatively efficient and inefficient AGN, respectively. We also test alternative ERDF shapes and mass dependent models. Our results are consistent with a mass independent AGN fraction and AGN hosts being randomly drawn from the galaxy population. We argue that the ERDF is not shaped by galaxy-scale effects, but by how efficiently material can be transported from the inner few parsecs to the accretion disc. Our results are incompatible with the simplest form of mass quenching where massive galaxies host higher accretion rate AGN. Furthermore, if reaching a certain Eddington ratio is a sufficient condition for maintenance mode, it can occur in all red galaxies, not just the most massive ones.

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“…Therefore, we have chosen to derive L Bol from L 14-195keV using the bolometric correction of L Bol =15 L 14-195keV  (Vasudevan et al 2009). Although this choice means we can only use 8 of the 16AGNs in the BATsystems, the use of ultra-hard X-rays mitigates the effect of nuclear obscuration (Koss et al 2011a). =-+ -, corresponding to a slope with a 0.02σsignificance from zero.…”

Section: Dependence Of the Agn Merger Fraction On Agn Bolometric Lumimentioning

confidence: 99%

Spatially Offset Active Galactic Nuclei. II. Triggering in Galaxy Mergers

Barrows

Comerford

Greene

et al. 2017

ApJ

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Galaxy mergers are likely to play a role in triggering active galactic nuclei (AGNs), but the conditions under which this process occurs are poorly understood. In Paper I, we constructed a sample of spatially offset X-ray AGNs that represent galaxy mergers hosting a single AGN. In this paper, we use our offset AGN sample to constrain the parameters that affect AGN observability in galaxy mergers. We also construct dual-AGN samples with similar selection properties for comparison. We find that the offset AGN fraction shows no evidence for a dependence on AGN luminosity, while the dual-AGN fractions show stronger evidence for a positive dependence, suggesting that the merger events forming dual AGNs are more efficient at instigating accretion onto supermassive black holes than those forming offset AGNs. We also find that the offset and dual-AGN fractions both have a negative dependence on nuclear separation and are similar in value at small physical scales. This dependence may become stronger when restricted to high AGN luminosities, although a larger sample is needed for confirmation. These results indicate that the probability of AGN triggering increases at later merger stages. This study is the first to systematically probe down to nuclear separations of <1 kpc (∼0.8 kpc) and is consistent with predictions from simulations that AGN observability peaks in this regime. We also find that the offset AGNs are not preferentially obscured compared to the parent AGN sample, suggesting that our selection may be targeting galaxy mergers with relatively dust-free nuclear regions.

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HOST GALAXY PROPERTIES OF THESWIFTBAT ULTRA HARD X-RAY SELECTED ACTIVE GALACTIC NUCLEUS

Cited by 147 publications

References 68 publications

The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at >10 keV

The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at >10 keV

AGNs and Their Host Galaxies in the Local Universe: Two Mass-independent Eddington Ratio Distribution Functions Characterize Black Hole Growth

Spatially Offset Active Galactic Nuclei. II. Triggering in Galaxy Mergers

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