BAT AGN Spectroscopic Survey (BASS) – VI. The ΓX–L/LEdd relation

Trakhtenbrot, Benny; Ricci, Cláudio; Koss, Michael; Schawinski, Kevin; Mushotzky, R. F.; Ueda, Yoshihiro; Veilleux, Sylvain; Lamperti, Isabella; Oh, Kyuseok; Treister, Ezequiel; Stern, Daniel; Harrison, Fiona A.; Baloković, Mislav; Gehrels, N.

doi:10.1093/mnras/stx1117

Cited by 104 publications

(100 citation statements)

References 71 publications

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“…It is due to smaller parameter range of ε, just like that for NLS1s. Thereofore, for the subsample of AGNs with single-epoch MBH , the correlation is not too significant, which is consistent with the result by Trakhtenbrot et al (2017) (their p null = 1.1 × 10 −3 ). For the subsample of 32 RM AGNs, this correlation is weaker with r = 0.25, p null = 0.165.…”

Section: The Relation Between the Photon Index And The Eddington Ratiosupporting

confidence: 89%

“…The magnetic stress t rφ is assumed be capable of transporting the angular momentum in the the Eddington ratio ε was extensively discussed by using different AGNs samples and by models (e.g. Bian et al 2003;Wang et al 2004;Yang et al 2006;Brightman et al 2013;Liu et al 2015;Meyer-Hofmeister et al 2017;Trakhtenbrot et al 2017). Trakhtenbrot et al (2017) recently used a sample of 228 hard X-ray selected low-redshift AGNs drawn from the Swift/BAT AGN Spectroscopic Survey (BASS) to investigate this relation.…”

Section: Introductionmentioning

confidence: 99%

“…Bian et al 2003;Wang et al 2004;Yang et al 2006;Brightman et al 2013;Liu et al 2015;Meyer-Hofmeister et al 2017;Trakhtenbrot et al 2017). Trakhtenbrot et al (2017) recently used a sample of 228 hard X-ray selected low-redshift AGNs drawn from the Swift/BAT AGN Spectroscopic Survey (BASS) to investigate this relation. They found a weak but significant correlation between them, Γ = log(ε 0.167 ), and a dependence on the method to derive the SMBH mass.…”

Section: Introductionmentioning

confidence: 99%

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Hot corona properties of Swift/BAT-detected AGNs

Wang

Bian

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Using a sample of 208 broad-line active galactic nuclei (AGNs) from Swift/BAT AGN Spectroscopic Survey in ultra-hard X-ray band (14 − 195 keV), the hot corona properties are investigated, i.e. the fraction of gravitational energy dissipated in the hot corona and the hard X-ray photon index. The bolometric luminosity, L Bol , is calculated from host-corrected luminosity at 5100Å. Virial supermassive black hole masses (SMBH, M BH ) are calculated from the Hβ line width and the corresponding broad line region size-luminosity empirical relation at 5100Å. We find a strong anti-correlation between the fraction of energy released in corona (F X ≡ L 14−195keV /L Bol ) and the Eddington ratio (ε ≡ L Bol /L Edd ), F X ∝ ε −0.60±0.1 . It is found that this fraction also has a correlation with the SMBH mass, BH. Assuming that magnetic buoyancy and feild reconnection lead to the formation of a hot corona, our result favours the shear stress tensor being a proportion of the gas pressure. For our entire sample, it is found that the hard X-ray photon index Γ has a weak but significant correlation with the Eddington ratio, Γ = 2.17 + 0.21 log ε. However, this correlation is not robust because the relation is not statistically significant for its subsample of 32 RM AGNs with relatively reliable M BH or its subsample of 166 AGNs with singleepoch M BH . We do not find a statistically significant relation between the photon index and the Eddington ratio taking into account an additional dependence on F X . disk. Therefore, the fraction of FX ≡ LX/L Bol (LX and L Bol are the X-ray luminosity and the bolometric luminosity respectively) can be obtained if the magnetic stress and energy transportation are assumed (e.g. Merloni & Fabian 2002). This may give us a possible opportunity to test the working magnetic stress from hard X-ray observations. The relation between the fraction of energy dissipated in the corona FX and the Eddington ratio ε (ε ≡ L Bol /L Edd , L Edd is the Eddington luminosity) was investigated by some authors (e.g. Merloni & Fabian 2002;Wang et al. 2004;Yang et al. 2006). For a compiled sample of 56 AGNs from ASCA observation, Wang et al. (2004) found a relation between FX and ε as FX ∝ ε −0.64±0.09 , where the X-ray luminosity in 2 − 10 keV is used. Considering a larger sample of 98 AGNs, Yang et al. (2006) found FX ∝ ε −0.66 . These results supported the magnetic stress tensor being the form of t rφ ∝ Pgas, where Pgas is the gas pressure. In their compiled sample, they only have nine sources with ultra-hard X-ray observations of INTEGRAL and Swift, and for other sources the luminosity in 2 − 150 kev is extrapolated from the 2-10 keV luminosity with a fixed photon index. A sample of more AGNs with direct harder X-ray than 2-10 keV is needed for further investigation, such as Swift/BAT. Another relation between the X-ray photon index Γ and c 0000 The Authors

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Section: The Relation Between the Photon Index And The Eddington Ratiosupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hot corona properties of Swift/BAT-detected AGNs

Wang

Bian

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…While the average value of the X-ray spectral powerlaw index, Γ, for z > 5.7 quasars is Γ ∼ 1.9 (Nanni et al 2017), we found the spectrum of PJ308−21 was best fit with a softer value, Γ = 2.39 +0.37 −0.36 , which is one of the softest values for z > 6 quasars yet found (only considering those with reasonable constraints; Vito et al 2019b). A number of recent works have found a correlation between Γ and the Eddington ratio (e.g., Shemmer et al 2008, Brightman et al 2013, Brightman et al 2016; this is not without some controversy though, e.g., Trakhtenbrot et al 2017. Similarly, simulations (e.g., Hopkins et al 2006) predict that major mergers drive high accretion rates in AGN.…”

Section: Discussionmentioning

confidence: 98%

X-Ray Observations of a z ∼ 6.2 Quasar/Galaxy Merger

Connor¹,

Bañados²,

Stern³

et al. 2019

ApJ

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Quasars at early redshifts (z > 6) with companion galaxies offer unique insights into the growth and evolution of the first supermassive black holes. Here, we report on a 150 ks Chandra observation of PSO J308.0416−21.2339, a z = 6.23 quasar with a merging companion galaxy identified in [C II] and rest-frame UV emission. With 72.3 +9.6 −8.6 net counts, we find that PSO J308.0416−21.2339 is powerful (L X = 2.31 +1.14 −0.76 × 10 45 erg s −1 cm −2 in rest frame 2.0 − 10.0 keV) yet soft (spectral power-law index Γ = 2.39 +0.37 −0.36 and optical-to-X-ray slope α OX = −1.41 ± 0.11). In addition, we detect three hard-energy photons 2. 0 to the west of the main quasar, cospatial with the brightest UV emission of the merging companion. As no soft energy photons are detected in the same area, this is potentially indicative of a highly-obscured source. With conservative assumptions, and accounting for both background fluctuations and the extended wings of the quasar's emission, these photons represent a 2.4σ detection. If confirmed by deeper observations, this system is the first high redshift quasar and companion individually detected in X-rays and is likely a dual AGN.

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“…The relation between Γ and the Eddington ratio has been established over a range of redshifts for sizable samples of sources: steeper slopes correspond to higher implied Eddington ratios (e.g. Shemmer et al 2008;Risaliti et al 2009;Brightman et al 2013;Fanali et al 2013, but see also Trakhtenbrot et al 2017a).…”

Section: Introductionmentioning

confidence: 99%

The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe

Vito

Brandt

Bauer

et al. 2019

A&A

104

150

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Context. X-ray emission from quasars (QSOs) has been used to assess supermassive black hole (SMBH) accretion properties up to z ≈ 6. However, at z > 6 only ≈ 15 QSOs are covered by sensitive X-ray observations, preventing a statistically significant investigation of the X-ray properties of the QSO population in the first Gyr of the Universe. Aims. We present new Chandra observations of a sample of 10 z > 6 QSOs, selected to have virial black-hole mass estimates from Mg II line spectroscopy (log M BH M = 8.5 − 9.6). Adding archival X-ray data for an additional 15 z > 6 QSOs, we investigate the X-ray properties of the QSO population in the first Gyr of the Universe, focusing in particular on the L UV − L X relation, which is traced by the α ox parameter, and the shape of their X-ray spectra. Methods. We performed photometric analyses to derive estimates of the X-ray luminosities of our z > 6 QSOs, and thus their α ox values and bolometric corrections (K bol = L bol /L X ). We compared the resulting α ox and K bol distributions with the results found for QSO samples at lower redshift, and ran several statistical tests to check for a possible evolution of the L UV − L X relation. Finally, we performed a basic X-ray spectral analysis of the brightest z > 6 QSOs to derive their individual photon indices, and joint spectral analysis of the whole sample to estimate the average photon index. Results. We detected seven of the new Chandra targets in at least one standard energy band, while two more are detected discarding energies E > 5 keV, where background dominates. We confirm a lack of significant evolution of α ox with redshift, extending the results from previous works up to z > 6 with a statistically significant QSO sample, and the trend of an increasing bolometric correction with increasing luminosity found for QSOs at lower redshifts. The average power-law photon index of our sample ( Γ = 2.20 +0.39 −0.34 and Γ = 2.13 +0.13 −0.13 for sources with < 30 and > 30 net counts, respectively) is slightly steeper than, but still consistent with, typical QSOs at z = 1 − 6. Conclusions. All these results point toward a lack of substantial evolution of the inner accretion-disk/hot-corona structure in QSOs from low redshift to z > 6. Our data hint at generally high Eddington ratios at z > 6.

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BAT AGN Spectroscopic Survey (BASS) – VI. The ΓX–L/LEdd relation

Cited by 104 publications

References 71 publications

Hot corona properties of Swift/BAT-detected AGNs

Hot corona properties of Swift/BAT-detected AGNs

X-Ray Observations of a z ∼ 6.2 Quasar/Galaxy Merger

The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe

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