Observational constraints on the dependence of radio-quiet quasar X-ray emission on black hole mass and accretion rate

Brandon C. Kelly; Jill Bechtold; Jonathan R. Trump; Marianne Vestergaard; Meta Siemiginowska

doi:10.1086/533440

Observational constraints on the dependence of radio-quiet quasar X-ray emission on black hole mass and accretion rate

Brandon C. Kelly, Jill Bechtold, Jonathan R. Trump, Marianne Vestergaard, Meta Siemiginowska

75 Citationer (Scopus)

Abstract

In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, α_ox, and the X-ray photon index, Γ_X , on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of Γ_X from Chandra. We estimate MBH using standard estimates derived from the HβMg II, and C IV broad emission lines. Our sample spans a broad range in black hole mass (10⁶ ≲ M _BH/M_⊙ ≲ 10¹⁰), redshift (0 < z < 4.8), and luminosity (10⁴³ ≲ λL_λ (2500 Å)[ergs s^-1] ≲ 1048). We find that α_ox increases with increasing M_BH and L _UV/L_Edd and decreases with increasing L_X/L _Edd. In addition, we confirm the correlation seen in previous studies between Γ_X and M_BH and both L_UV/L _Edd and L_X/L_Edd; however, we also find evidence that the dependence of Γ_X of these quantities is not monotonic, changing sign at M_BH ∼ 3 × 10⁸ M _⊙. We argue that the α_ox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to the Eddington rate, ṁ. In addition, we argue that the Γ_X trends are caused by a dependence of X-ray spectral index on ṁ. We discuss our results within the context of accretion models with Comptonizing corona and discuss the implications of the α_ox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.

Originalsprog	Engelsk
Tidsskrift	Astrophysical Journal, Supplement Series
Vol/bind	176
Udgave nummer	2
Sider (fra-til)	355-373
Antal sider	19
ISSN	0067-0049
DOI	https://doi.org/10.1086/533440
Status	Udgivet - 1 jun. 2008
Udgivet eksternt	Ja

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title = "Observational constraints on the dependence of radio-quiet quasar X-ray emission on black hole mass and accretion rate",

abstract = "In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, αox, and the X-ray photon index, ΓX , on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of ΓX from Chandra. We estimate MBH using standard estimates derived from the HβMg II, and C IV broad emission lines. Our sample spans a broad range in black hole mass (106 ≲ M BH/M⊙ ≲ 1010), redshift (0 < z < 4.8), and luminosity (1043 ≲ λLλ (2500 {\AA})[ergs s-1] ≲ 1048). We find that αox increases with increasing MBH and L UV/LEdd and decreases with increasing LX/L Edd. In addition, we confirm the correlation seen in previous studies between ΓX and MBH and both LUV/L Edd and LX/LEdd; however, we also find evidence that the dependence of ΓX of these quantities is not monotonic, changing sign at MBH ∼ 3 × 108 M ⊙. We argue that the αox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to the Eddington rate, ṁ. In addition, we argue that the ΓX trends are caused by a dependence of X-ray spectral index on ṁ. We discuss our results within the context of accretion models with Comptonizing corona and discuss the implications of the αox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.",

keywords = "Accretion, accretion disks, Galaxies: active, Quasars: general, Ultraviolet: galaxies, X-rays: galaxies",

author = "Kelly, {Brandon C.} and Jill Bechtold and Trump, {Jonathan R.} and Marianne Vestergaard and Meta Siemiginowska",

year = "2008",

month = jun,

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doi = "10.1086/533440",

language = "English",

volume = "176",

pages = "355--373",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "Institute of Physics Publishing, Inc",

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TY - JOUR

T1 - Observational constraints on the dependence of radio-quiet quasar X-ray emission on black hole mass and accretion rate

AU - Kelly, Brandon C.

AU - Bechtold, Jill

AU - Trump, Jonathan R.

AU - Vestergaard, Marianne

AU - Siemiginowska, Meta

PY - 2008/6/1

Y1 - 2008/6/1

N2 - In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, αox, and the X-ray photon index, ΓX , on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of ΓX from Chandra. We estimate MBH using standard estimates derived from the HβMg II, and C IV broad emission lines. Our sample spans a broad range in black hole mass (106 ≲ M BH/M⊙ ≲ 1010), redshift (0 < z < 4.8), and luminosity (1043 ≲ λLλ (2500 Å)[ergs s-1] ≲ 1048). We find that αox increases with increasing MBH and L UV/LEdd and decreases with increasing LX/L Edd. In addition, we confirm the correlation seen in previous studies between ΓX and MBH and both LUV/L Edd and LX/LEdd; however, we also find evidence that the dependence of ΓX of these quantities is not monotonic, changing sign at MBH ∼ 3 × 108 M ⊙. We argue that the αox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to the Eddington rate, ṁ. In addition, we argue that the ΓX trends are caused by a dependence of X-ray spectral index on ṁ. We discuss our results within the context of accretion models with Comptonizing corona and discuss the implications of the αox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.

AB - In this work we use a sample of 318 radio-quiet quasars (RQQs) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, αox, and the X-ray photon index, ΓX , on black hole mass, UV relative to Eddington luminosity, and X-ray relative to Eddington luminosity. Our sample is drawn from the literature, with X-ray data from ROSAT and Chandra, and optical data mostly from the SDSS; 153 of these sources have estimates of ΓX from Chandra. We estimate MBH using standard estimates derived from the HβMg II, and C IV broad emission lines. Our sample spans a broad range in black hole mass (106 ≲ M BH/M⊙ ≲ 1010), redshift (0 < z < 4.8), and luminosity (1043 ≲ λLλ (2500 Å)[ergs s-1] ≲ 1048). We find that αox increases with increasing MBH and L UV/LEdd and decreases with increasing LX/L Edd. In addition, we confirm the correlation seen in previous studies between ΓX and MBH and both LUV/L Edd and LX/LEdd; however, we also find evidence that the dependence of ΓX of these quantities is not monotonic, changing sign at MBH ∼ 3 × 108 M ⊙. We argue that the αox correlations imply that the fraction of bolometric luminosity emitted by the accretion disk, as compared to the corona, increases with increasing accretion rate relative to the Eddington rate, ṁ. In addition, we argue that the ΓX trends are caused by a dependence of X-ray spectral index on ṁ. We discuss our results within the context of accretion models with Comptonizing corona and discuss the implications of the αox correlations for quasar feedback. To date, this is the largest study of the dependence of RQQ X-ray parameters on black hole mass and related quantities, and the first to attempt to correct for the large statistical uncertainty in the broad-line mass estimates.

KW - Accretion, accretion disks

KW - Galaxies: active

KW - Quasars: general

KW - Ultraviolet: galaxies

KW - X-rays: galaxies

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U2 - 10.1086/533440

DO - 10.1086/533440

M3 - Journal article

AN - SCOPUS:46349100612

SN - 0004-637X

VL - 176

SP - 355

EP - 373

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

ER -

Observational constraints on the dependence of radio-quiet quasar X-ray emission on black hole mass and accretion rate

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