ABSTRACT
We have performed a very long baseline interferometry (VLBI) survey of local (z < 0.05) ultrahard X-ray (14–195 keV) selected active galactic nuclei (AGNs) from the Swift Burst Alert ...Telescope (BAT) using KVN, KaVA, and VLBA. We first executed fringe surveys of 142 BAT-detected AGNs at 15 or 22 GHz. Based on the result from the fringe surveys and archival data, we find 10/279 nearby AGN (∼4 per cent) VLBI have 22 GHz flux above 30 mJy. This implies that the X-ray AGNs with a bright nuclear jet are not common. Among these 10 radio-bright AGNs, we obtained 22 GHz VLBI imaging data of our own for four targets and reprocessed archival data for six targets. We find that, although our 10 AGNs observed with VLBI span a wide range of pc-scale morphological types, they lie on a tight linear relation between accretion luminosity and nuclear jet luminosity. Our result suggests that a powerful nuclear radio jet correlates with the accretion disc luminosity. We also probed the Fundamental Plane of black hole activity at VLBI scales (e.g. few milliarcsecond). The jet luminosity and size distribution among our sample roughly fit into the proposed AGN evolutionary scenario, finding powerful jets after the blow-out phase based on the Eddington ratio (λEdd)–hydrogen column density (NH) relation. In addition, we find some hints of gas inflow or galaxy–galaxy merger in the majority of our sample. This implies that gas supply via tidal interactions in galactic scale may help the central AGN to launch a powerful parsec-scale jet.
Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation ...emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow.
We present the host-galaxy molecular gas properties of a sample of 213 nearby (0.01 < z < 0.05) hard-X-ray-selected active galactic nucleus (AGN) galaxies, drawn from the 70-month catalog of Swift's ...Burst Alert Telescope (BAT), with 200 new CO(2-1) line measurements obtained with the James Clerk Maxwell Telescope and the Atacama Pathfinder Experiment telescope. We find that AGN in massive galaxies ( ) tend to have more molecular gas and higher gas fractions than inactive galaxies matched in stellar mass. When matched in star formation, we find AGN galaxies show no difference from inactive galaxies, with no evidence that AGN feedback affects the molecular gas. The higher molecular gas content is related to AGN galaxies hosting a population of gas-rich early types with an order of magnitude more molecular gas and a smaller fraction of quenched, passive galaxies (∼5% versus 49%) compared to inactive galaxies. The likelihood of a given galaxy hosting an AGN (Lbol > 1044 erg s−1 ) increases by ∼10-100 between a molecular gas mass of 108.7M and 1010.2M . AGN galaxies with a higher Eddington ratio (log(L/LEdd) > −1.3) tend to have higher molecular gas masses and gas fractions. The log(NH/ cm−2 ) > 23.4) of AGN galaxies with higher column densities are associated with lower depletion timescales and may prefer hosts with more gas centrally concentrated in the bulge that may be more prone to quenching than galaxy-wide molecular gas. The significant average link of host-galaxy molecular gas supply to supermassive black hole (SMBH) growth may naturally lead to the general correlations found between SMBHs and their host galaxies, such as the correlations between SMBH mass and bulge properties, and the redshift evolution of star formation and SMBH growth.
Abstract
Recent studies have proposed that the nuclear millimeter continuum emission observed in nearby active galactic nuclei (AGNs) could be created by the same population of electrons that gives ...rise to the X-ray emission that is ubiquitously observed in accreting black holes. We present the results of a dedicated high-spatial-resolution (∼60–100 mas) Atacama Large Millimeter/submillimeter Array (ALMA) campaign on a volume-limited (<50 Mpc) sample of 26 hard X-ray (>10 keV) selected radio-quiet AGNs. We find an extremely high detection rate (25/26 or
94
−
6
+
3
%
), which shows that nuclear emission at millimeter wavelengths is nearly ubiquitous in accreting SMBHs. Our high-resolution observations show a tight correlation between the nuclear (1–23 pc) 100 GHz and the intrinsic X-ray emission (1
σ
scatter of 0.22 dex). The ratio between the 100 GHz continuum and the X-ray emission does not show any correlation with column density, black hole mass, Eddington ratio, or star formation rate, which suggests that the 100 GHz emission can be used as a proxy of SMBH accretion over a very broad range of these parameters. The strong correlation between 100 GHz and X-ray emission in radio-quiet AGNs could be used to estimate the column density based on the ratio between the observed 2–10 keV (
F
2
–
10
keV
obs
) and 100 GHz (
F
100 GHz
) fluxes. Specifically, a ratio
log
(
F
2
–
10
keV
obs
/
F
100
GHz
)
≤
3.5
strongly suggests that a source is heavily obscured (
log
(
N
H
/
cm
−
2
)
≳
23.8
). Our work shows the potential of ALMA continuum observations to detect heavily obscured AGNs (up to an optical depth of one at 100 GHz, i.e.,
N
H
≃ 10
27
cm
−2
), and to identify binary SMBHs with separations <100 pc, which cannot be probed by current X-ray facilities.
The radiative efficiencies (η) of 72 luminous unobscured active galactic nuclei at z ∼ 1.5-3.5, powered by some of the most massive black holes (BHs), are constrained. The analysis is based on ...accretion disk (AD) models, which link the continuum luminosity at rest-frame optical wavelengths and the BH mass (M {sub BH}) to the accretion rate through the AD, M-dot {sub AD}. The data are gathered from several literature samples with detailed measurements of the Hβ emission line complex, observed at near-infrared bands. When coupled with standard estimates of bolometric luminosities (L {sub bol}), the analysis suggests high radiative efficiencies, with most of the sources showing η > 0.2, that is, higher than the commonly assumed value of 0.1, and the expected value for non-spinning BHs (η = 0.057). Even under more conservative assumptions regarding L {sub bol} (i.e., L {sub bol} = 3 × L {sub 5100}), most of the extremely massive BHs in the sample (i.e., M {sub BH} ≳ 3 × 10{sup 9} M {sub ☉}) show radiative efficiencies which correspond to very high BH spins (a {sub *}), with typical values well above a {sub *} ≅ 0.7. These results stand in contrast to the predictions of a ''spin-down'' scenario, in which a series of randomly oriented accretion episodes leads to a {sub *} ∼ 0. Instead, the analysis presented here strongly supports a ''spin-up'' scenario, which is driven by either prolonged accretion or a series of anisotropically oriented accretion episodes. Considering the fact that these extreme BHs require long-duration or continuous accretion to account for their high masses, it is argued that the most probable scenario for the super-massive black holes under study is that of an almost continuous sequence of randomly yet not isotropically oriented accretion episodes.
Abstract In this study, we use the Swift/BAT AGN sample, which has received extensive multiwavelength follow-up analysis as a result of the BAT AGN Spectroscopic Survey, to develop a diagnostic for ...nuclear obscuration by examining the relationship between the line-of-sight column densities ( N H ), the 2–10 keV to 12 μ m luminosity ratio, and WISE mid-infrared colors. We demonstrate that heavily obscured AGNs tend to exhibit both preferentially “redder” mid-infrared colors and lower values of L X,Obs. / L 12 μ m than less obscured AGNs, and we derive expressions relating N H to the L X,Obs. / L 12 μ m and L 22 μ m / L 4.6 μ m luminosity ratios, as well as develop diagnostic criteria using these ratios. Our diagnostic regions yield samples that are ≳80% complete and ≳60% pure for AGNs with log( N H /cm −2 ) ≥ 24, as well as ≳85% pure for AGNs with log ( N H / cm − 2 ) ≳ 23.5 . We find that these diagnostics cannot be used to differentiate between optically star-forming galaxies and active galaxies. Further, mid-IR contributions from host galaxies that dominate the observed 12 μ m emission can lead to larger apparent X-ray deficits and redder mid-IR colors than the AGNs would intrinsically exhibit, though this effect helps to better separate less and more obscured AGNs. Finally, we test our diagnostics on two catalogs of AGNs and infrared galaxies, including the XMM-Newton XXL-N field, and we identify several known Compton-thick AGNs, as well as a handful of candidate heavily obscured AGNs based upon our proposed obscuration diagnostics.
Abstract We present the BAT AGN Spectroscopic Survey (BASS) Near-infrared Data Release 2 (DR2), a study of 168 nearby ( z ¯ = 0.04 , z < 0.6) active galactic nuclei (AGN) from the all-sky Swift Burst ...Array Telescope X-ray survey observed with the Very Large Telescope (VLT)/X-shooter in the near-infrared (NIR; 0.8–2.4 μ m). We find that 49/109 (45%) Seyfert 2 and 35/58 (60%) Seyfert 1 galaxies observed with VLT/X-shooter show at least one NIR high-ionization coronal line (CL; ionization potential χ > 100 eV). Comparing the emission of the Si vi λ 1.9640 CL with the X-ray emission for the DR2 AGN, we find a significantly tighter correlation, with a lower scatter (0.37 dex) than that for the optical O iii λ 5007 line (0.71 dex). We do not find any correlation between CL emission and the X-ray photon index Γ. We find a clear trend of line blueshifts with increasing ionization potential in several CLs, such as Si vi λ 1.9640, Si x λ 1.4300, S viii λ 0.9915, and S ix λ 1.2520, indicating the radial structure of the CL region. Finally, we find a strong underestimation bias in black hole mass measurements of Sy 1.9 using broad H α due to the presence of significant dust obscuration. In contrast, the broad Pa α and Pa β emission lines are in agreement with the M – σ relation. Based on the combined DR1 and DR2 X-shooter sample, the NIR BASS sample now comprises 266 AGN with rest-frame NIR spectroscopic observations, the largest set assembled to date.
Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we ...present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4-1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C IV) to low-ionization lines (e.g., Mg II, Hbeta, Halpha) in individual objects. We detect broad Hbeta and Halpha emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hbeta has rest-frame equivalent widths ranging from 15-40 A). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe II emission, HbetaFWHM lap 4000 km s super(-1), and significant C IV blueshifts ( approximately 1000-5500 km s super(-1)) relative to the systemic redshift; two spectra also show elevated UV Fe II emission, and an outflowing component to their (weak) Mg II emission lines. These properties suggest that WLQs are exotic versions of "wind-dominated" quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum.
We present new H- and K-band spectroscopy of 15 high-luminosity active galactic nuclei (AGNs) at redshifts 2.3-3.4 obtained with Gemini South. We combined the data with spectra of an additional 29 ...high-luminosity sources to obtain a sample with 10 super(45.2) < lambda L sub( lambda )(5100 A) < 10 super(47.3) ergs s super(-1) and a black hole (BH) mass range, using reverberation mapping relationships based on the H beta method, of 10 super(8.8)-10 super(10.7) M unk. We do not find a correlation of L/L sub(Edd) with M sub(BH), but we do find a correlation with lambda L sub( lambda )(5100 A), which might be due to selection effects. The L/L sub(Edd) distribution is broad and covers the range of similar to 0.07-1.6, similar to what is observed in lower redshift, lower luminosity AGNs. We suggest that this consistently measured and calibrated sample gives the best representation of L/L sub(Edd) at those redshifts, and note potential discrepancies with recent theoretical and observational studies. The lower accretion rates are not in accord with growth scenarios for BHs at such redshifts, and the growth times of many of the sources are longer than the age of the universe at the corresponding epochs. This suggests earlier episodes of faster growth at z unk 3 for those sources. The use of the C IV lambda 1549 method gives considerably different results and a larger scatter; this method seems to be a poor M sub(BH) and L/L sub(Edd) estimator at very high luminosity.
Abstract
We present multiwavelength high-spatial resolution (∼0.″1, 70 pc) observations of UGC 4211 at
z
= 0.03474, a late-stage major galaxy merger at the closest nuclear separation yet found in ...near-IR imaging (0.″32, ∼230 pc projected separation). Using Hubble Space Telescope/Space Telescope Imaging Spectrograph, Very Large Telescope/MUSE+AO, Keck/OSIRIS+AO spectroscopy, and the Atacama Large Millimeter/submillimeter Array (ALMA) observations, we show that the spatial distribution, optical and near-infrared emission lines, and millimeter continuum emission are all consistent with both nuclei being powered by accreting supermassive black holes (SMBHs). Our data, combined with common black hole mass prescriptions, suggest that both SMBHs have similar masses,
log
M
BH
/
M
⊙
∼ 8.1 (south) and
log
M
BH
/
M
⊙
∼ 8.3 (north), respectively. The projected separation of 230 pc (∼6× the black hole sphere of influence) represents the closest-separation dual active galactic nuclei (AGN) studied to date with multiwavelength resolved spectroscopy and shows the potential of nuclear (<50 pc) continuum observations with ALMA to discover hidden growing SMBH pairs. While the exact occurrence rate of close-separation dual AGN is not yet known, it may be surprisingly high, given that UGC 4211 was found within a small, volume-limited sample of nearby hard X-ray detected AGN. Observations of dual SMBH binaries in the subkiloparsec regime at the final stages of dynamical friction provide important constraints for future gravitational wave observatories.
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