BASS. XXII. The BASS DR2 AGN Catalog and Data Koss, Michael J.; Ricci, Claudio; Trakhtenbrot, Benny ...
The Astrophysical journal. Supplement series,
07/2022, Letnik:
261, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract We present the active galactic nucleus (AGN) catalog and optical spectroscopy for the second data release of the Swift BAT AGN Spectroscopic Survey (BASS DR2). With this DR2 release we ...provide 1449 optical spectra, of which 1182 are released for the first time, for the 858 hard-X-ray-selected AGNs in the Swift BAT 70-month sample. The majority of the spectra (801/1449, 55%) are newly obtained from Very Large Telescope (VLT)/X-shooter or Palomar/Doublespec. Many of the spectra have both higher resolution ( R > 2500, N ∼ 450) and/or very wide wavelength coverage (3200–10000 Å, N ∼ 600) that are important for a variety of AGN and host galaxy studies. We include newly revised AGN counterparts for the full sample and review important issues for population studies, with 47 AGN redshifts determined for the first time and 790 black hole mass and accretion rate estimates. This release is spectroscopically complete for all AGNs (100%, 858/858), with 99.8% having redshift measurements (857/858) and 96% completion in black hole mass estimates of unbeamed AGNs (722/752). This AGN sample represents a unique census of the brightest hard-X-ray-selected AGNs in the sky, spanning many orders of magnitude in Eddington ratio ( L / L Edd = 10 −5 –100), black hole mass ( M BH = 10 5 –10 10 M ⊙ ), and AGN bolometric luminosity ( L bol = 10 40 –10 47 erg s −1 ).
BASS. XXI. The Data Release 2 Overview Koss, Michael J.; Trakhtenbrot, Benny; Ricci, Claudio ...
The Astrophysical journal. Supplement series,
07/2022, Letnik:
261, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract The BAT AGN Spectroscopic Survey (BASS) is designed to provide a highly complete census of the key physical parameters of the supermassive black holes (SMBHs) that power local active ...galactic nuclei (AGNs) ( z ≲ 0.3), including their bolometric luminosity ( L bol ), black hole (BH) mass ( M BH ), accretion rates ( L bol / L Edd ), line-of-sight gas obscuration ( N H ), and the distinctive properties of their host galaxies (e.g., star formation rates, masses, and gas fractions). We present an overview of the second data release of BASS (DR2), an unprecedented spectroscopic AGN survey in spectral range, resolution, and sensitivity, including 1449 optical (∼3200 Å–1 μ m) and 233 near-IR (1–2.5 μ m) spectra for the brightest 858 ultrahard X-ray (14–195 keV) selected AGNs across the entire sky and essentially all levels of obscuration. This release provides a highly complete set of key measurements (emission-line measurements and central velocity dispersions), with 99.9% measured redshifts and 98% BH masses estimated (for unbeamed AGNs outside the Galactic plane). The BASS DR2 AGN sample represents a unique census of nearby powerful AGNs, spanning over 5 orders of magnitude in AGN bolometric luminosity ( L bol ∼ 10 40 –10 47 erg s −1 ), BH mass ( M BH ∼ 10 5 –10 10 M ⊙ ), Eddington ratio ( L bol / L Edd ≳ 10 −5 ), and obscuration ( N H ∼ 10 20 –10 25 cm −2 ). The public BASS DR2 sample and measurements can thus be used to answer fundamental questions about SMBH growth and its links to host galaxy evolution and feedback in the local universe, as well as open questions concerning SMBH physics. Here we provide a brief overview of the survey strategy, the key BASS DR2 measurements, data sets and catalogs, and scientific highlights from a series of DR2-based works pursued by the BASS team.
Abstract
We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically ...detected SDSS sources with redshift measurements, combined additional broadband photometry from WISE, UKIDSS, 2MASS, and GALEX, and modeled the spectral energy distributions (SEDs) of our sample sources. We parameterize nuclear obscuration in our SEDs with
and uncover thousands of powerful obscured AGNs that lack X-ray counterparts, many of which are identified as AGN candidates based on straightforward WISE photometric criteria. Using the observed luminosity correlation between rest-frame 2–10 keV (
) and rest-frame AGN
(
), we estimate the intrinsic X-ray luminosities of our sample sources and combine these data with flux limits from X-ray catalogs to determine lower limits on nuclear obscuration. Using the ratio of intrinsic-to-observed X-ray luminosity (
), we find a significant fraction of sources with column densities approaching
cm
–2
, suggesting that multiwavelength observations are necessary to account for the population of heavily obscured AGNs. We simulate the underlying
distribution for the X-ray non-detected sources in our sample through survival analysis, and confirm the presence of AGN activity via X-ray stacking. Our results point to a considerable population of extremely obscured AGNs undetected by current X-ray observatories.
Abstract
We present new estimates on the fraction of heavily X-ray-obscured, Compton-thick (CT) active galactic nuclei (AGNs) out to a redshift of
z
≤ 0.8. From a sample of 540 AGNs selected by ...mid-infrared (MIR) properties in observed X-ray survey fields, we forward model the observed-to-intrinsic X-ray luminosity ratio (
R
L
X
) with a Markov Chain Monte Carlo simulation to estimate the total fraction of CT AGNs (
f
CT
), many of which are missed in typical X-ray observations. We create model
N
H
distributions and convert these to
R
L
X
using a set of X-ray spectral models. We probe the posterior distribution of our models to infer the population of X-ray-nondetected sources. From our simulation we estimate a CT fraction of
f
CT
=
0.555
−
0.032
+
0.037
. We perform an X-ray stacking analysis for sources in Chandra X-ray Observatory fields and find that the expected soft (0.5–2 keV) and hard (2–7 keV) observed fluxes drawn from our model to be within 0.48 and 0.12 dex of our stacked fluxes, respectively. Our results suggests at least 50% of all MIR-selected AGNs, possibly more, are CT (
N
H
≳ 10
24
cm
−2
), which is in excellent agreement with other recent work using independent methods. This work indicates that the total number of AGNs is higher than can be identified using X-ray observations alone, highlighting the importance of a multiwavelength approach. A high
f
CT
also has implications for black hole (BH) accretion physics and supports models of BH and galaxy coevolution that include periods of heavy obscuration.
ABSTRACT
The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local ...Mbh–Mstar relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work, we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving Mbh–Mstar relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local Mbh–Mstar relation requires a mean radiative efficiency ε ≳ 0.15, in line with theoretical expectations for accretion on to spinning black holes. However, matching the ‘raw’ observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12–0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized.
Abstract
We present two independent measurements of stellar velocity dispersions (
σ
⋆
) from the Ca
ii
H+K
λ
3969, 3934 and Mg
i
b
λ
5183, 5172, 5167 region (3880–5550 Å) and the calcium triplet ...region (8350–8750 Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs;
z
≤ 0.08) from the 105 month Swift-BAT catalog. We construct one of the largest samples of local Type 1 AGNs that have both single-epoch
virial
black hole mass (
M
BH
) estimates and
σ
⋆
measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent
σ
⋆
measurements are highly consistent with each other, with an average offset of only 0.002 ± 0.001 dex. Comparing
M
BH
estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by ≈0.12 dex. Consequently, Eddington ratios estimated through broad-line
M
BH
determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the
M
BH
–
σ
⋆
relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower
M
BH
–
σ
⋆
relation (with a power-law exponent of ≈3.5) compared with that of inactive galaxies (with a power-law exponent of ≈4.5), confirming earlier results obtained from smaller samples.
We present two independent measurements of stellar velocity dispersions (σ⋆) from the Ca ii H+K λ3969, 3934 and Mg ibλ 5183, 5172, 5167 region (3880–5550 Å) and the calcium triplet region (8350–8750 ...Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs; z ≤ 0.08) from the 105 month Swift-BAT catalog. We construct one of the largest samples of local Type 1 AGNs that have both single-epoch virial black hole mass (MBH) estimates and σ⋆ measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent σ⋆ measurements are highly consistent with each other, with an average offset of only 0.002 ± 0.001 dex. Comparing MBH estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by ≈0.12 dex. Consequently, Eddington ratios estimated through broad-line MBH determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the MBH–σ⋆ relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower MBH–σ⋆ relation (with a power-law exponent of ≈3.5) compared with that of inactive galaxies (with a power-law exponent of ≈4.5), confirming earlier results obtained from smaller samples.
We present new estimates on the fraction of heavily X-ray obscured, Compton-thick (CT) active galactic nuclei (AGNs) out to a redshift of \(z \leq\) 0.8. From a sample of 540 AGNs selected by mid-IR ...(MIR) properties in observed X-ray survey fields, we forward model the observed-to-intrinsic X-ray luminosity ratio (\(R_{L_{\text{X}}}\)) with a Markov chain Monte Carlo (MCMC) simulation to estimate the total fraction of CT AGNs (\(f_{\text{CT}}\)), many of which are missed in typical X-ray observations. We create model \(N_{\text{H}}\) distributions and convert these to \(R_{L_{\text{X}}}\) using a set of X-ray spectral models. We probe the posterior distribution of our models to infer the population of X-ray non-detected sources. From our simulation we estimate a CT fraction of \(f_{\text{CT}}\) = \(\text{0.555}^{+\text{0.037}}_{-\text{0.032}}\). We perform an X-ray stacking analysis for sources in Chandra X-ray Observatory fields and find that the expected soft (0.5-2 keV) and hard (2-7 keV) observed fluxes drawn from our model to be within 0.48 and 0.12 dex of our stacked fluxes, respectively. Our results suggests at least 50% of all MIR-selected AGNs, possibly more, are Compton-thick (\(N_{\text{H}} \gtrsim\) 10\(^{\text{24}}\) cm\(^{-\text{2}}\)), which is in excellent agreement with other recent work using independent methods. This work indicates that the total number of AGNs is higher than can be identified using X-ray observations alone, highlighting the importance of a multiwavelength approach. A high \(f_{\text{CT}}\) also has implications for black hole (BH) accretion physics and supports models of BH and galaxy co-evolution that include periods of heavy obscuration.
We present two independent measurements of stellar velocity dispersions (
$\sigma_\rm{\star}$ ) from the Ca\,H+K \& Mg\,\textsc{i} region
(3880--5550~\AA) and the Calcium Triplet region (CaT, ...8350--8750~\AA) for 173
hard X-ray-selected Type 1 AGNs ($z \leq$ 0.08) from the 105-month Swift-BAT
catalog. We construct one of the largest samples of local Type 1 AGNs that have
both single-epoch (SE) 'virial' black hole mass ($M_\rm{BH}$) estimates and
$\sigma_\rm{\star}$ measurements obtained from high spectral resolution data,
allowing us to test the usage of such methods for SMBH studies. We find that
the two independent $\sigma_\rm{\star}$ measurements are highly consistent with
each other, with an average offset of only $0.002\pm0.001$ dex. Comparing
$M_\rm{BH}$ estimates based on broad emission lines and stellar velocity
dispersion measurements, we find that the former is systematically lower by
$\approx$0.12 dex. Consequently, Eddington ratios estimated through broad-line
$M_\rm{BH}$ determinations are similarly biased (but in the opposite way). We
argue that the discrepancy is driven by extinction in the broad-line region
(BLR). We also find an anti-correlation between the offset from the $M_\rm{BH}$
- $\sigma_\rm{\star}$ relation and the Eddington ratio. Our sample of Type 1
AGNs shows a shallower $M_\rm{BH}$ - $\sigma_\rm{\star}$ relation (with a power
law exponent of $\approx$3.5) compared with that of inactive galaxies (with a
power-law exponent of $\approx$4.5), confirming earlier results obtained from
smaller samples.
We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically detected SDSS ...sources with redshift measurements, combined additional broadband photometry from WISE, UKIDSS, 2MASS, and GALEX, and modeled the spectral energy distributions (SEDs) of our sample sources. We parameterize nuclear obscuration in our SEDs with \(E(B\!-\!V)_{\text{AGN}}\) and uncover thousands of powerful obscured AGNs that lack X-ray counterparts, many of which are identified as AGN candidates based on straightforward WISE photometric criteria. Using the observed luminosity correlation between restframe 2-10 keV (\(L_{\text{X}}\)) and restframe AGN 6 \(\mu{\text{m}}\) (\(L_{\text{MIR}}\)), we estimate the intrinsic X-ray luminosities of our sample sources and combine these data with flux limits from X-ray catalogs to determine lower limits on nuclear obscuration. Using the ratio of intrinsic-to-observed X-ray luminosity (\(R_{L_{\text{X}}}\)), we find a significant fraction of sources with column densities approaching \(N_{\text{H}}>\) 10\(^{\text{24}}\) cm\(^{-{\text{2}}}\), suggesting that multiwavelength observations are necessary to account for the population of heavily obscured AGNs. We simulate the underlying \(N_{\text{H}}\) distribution for the X-ray non-detected sources in our sample through survival analysis, and confirm the presence of AGN activity via X-ray stacking. Our results point to a considerable population of extremely obscured AGNs undetected by current X-ray observatories.
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