A two-phase model for the X-ray emission from Seyfert galaxies

Haardt, Francesco; Maraschi, L.

doi:10.1086/186171

Cited by 993 publications

(996 citation statements)

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“…The tight constraint on the spin of the black hole in this gravitationally lensed quasar represents a robust measurement of black hole spin beyond our local universe. The compact nature of the Xray corona returned by the relativistic reflection model used herein confirms the prior micro-lensing analysis [15,16], and hence moves the basic picture of X-ray emission in quasars away from large X-ray coronae [27] that may blanket at least the inner disk, and more towards a compact emitting region in the very innermost parts of the accretion flow, consistent with models for the base of a jet [28].…”

supporting

confidence: 84%

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Reis

Reynolds

Miller

et al. 2014

Nature

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The co-evolution of a supermassive black hole with its host galaxy[1] through cosmic time is encoded in its spin[2, 3, 4]. At z > 2, supermassive black holes are thought to grow mostly by merger-driven accretion leading to high spin. However, it is unknown whether below z ∼ 1 these black holes continue to grow via coherent accretion or in a chaotic manner [5], though clear differences are predicted [3,4] in their spin evolution. An established method[6] to measure the spin of black holes is via the study of relativistic reflection features [7] from the inner accretion disk. Owing to their greater distances, there has hitherto been no significant detection of relativistic reflection features in a moderateredshift quasar. Here, we use archival data together with a new, deep observation of a gravitationally-lensed quasar at z = 0.658 to rigorously detect and study reflection in this moderate-redshift quasar. The level of relativistic distortion present in this reflection spectrum enables us to constrain the emission to originate within 3 gravitational radii from the black hole, implying a spin parameter a = 0.87 +0.08 −0.15 at the 3σ level of confidence and a > 0.66 at the 5σ level. The high spin found here is indicative of growth via coherent accretion for this black hole, and suggests that black hole growth between 0.5 z 1 occurs principally by coherent rather than chaotic accretion episodes. 1When optically-thick material, e.g. an accretion disc, is irradiated by hard X-rays, some of the flux is reprocessed into an additional 'reflected' emission component, which contains both continuum emission and atomic features. The most prominent signature of reflection from the inner accretion disc is typically the relativistic iron Kα line (6.4-6.97 keV; rest frame) [8] and the Compton reflection hump [7] often peaking at 20 − 30 keV (rest-frame). However, the deep gravitational potential and strong Doppler shifts associated with regions around black holes will also cause the forest of soft X-ray emission lines in the ∼ 0.7 − 2.0 keV range to be blended into a smooth emission feature, providing a natural explanation for the "soft-excess" observed in the X-ray spectra of nearby active galactic nuclei (AGNs) [9,10]. Indeed, both the iron line and the soft excess can be used to provide insight into the nature of the central black hole and to measure its spin [10]. Prior studies have revealed the presence of a soft-excess in 90% of quasars at[11, 12] z 1.7, and broad Fe-lines are also seen in 25% of these objects [11,13], suggesting that reflection is also prevalent in these distant AGNs. However, due to the inadequate S/N resulting from their greater distances, the X-ray spectra of these quasars were necessarily modeled using simple phenomenological parameterizations [12,14].Gravitational lensing offers a rare opportunity to study the innermost relativistic region in distant quasars [15,16], by acting as a natural telescope and magnifying the light from these sources. Quasars located between 0.5 z 1 are considerably ...

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supporting

confidence: 84%

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Reis

Reynolds

Miller

et al. 2014

Nature

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“…We see that generally the spectrum steepens with increasing optical depth. Analogous trends were already seen by Haardt & Maraschi (1991) as well as for example by Abrassart & Czerny (2000) when they fixed the spectral slope but determined the amplification factor as a function of the temperature of the medium. The effect is more strongly visible for the slope measured in a narrower band since the spectrum displays some curvature due to the low value of the electron temperature.…”

Section: Radiation Spectrum From Disk/warm Skin Systemsupporting

confidence: 79%

“…The obtained value of the Compton amplification factor, A = 2, for the warm skin of a marginally stable disk interior, w = 0.5, is significantly lower than the value A ∼ 3 determined from the model of Haardt & Maraschi (1991) for the corona-dominated solution (f = 1, a = 0 in their Eq. (3b)).…”

Section: Marginal Stability Solution For the Warm Skincontrasting

confidence: 64%

“…Our model therefore roughly corresponds to the original Haardt & Maraschi (1991) analytical model with the fraction of the energy dissipated in the corona f = 0.5 and the albedo a = 1. However, we provide a physical justification for the specific choice of f in the case of the underlying disk dominated by radiation pressure.…”

Section: Marginal Stability Solution For the Warm Skinmentioning

confidence: 65%

“…This is a typical assumption made in many disk/corona models (e.g. Haardt & Maraschi 1991;Misra & Taam 2002). We further assume that a fraction of the energy is transported from the disk interior towards the skin as a magnetic flux.…”

Section: General Stationary Model Of the Warm Skinmentioning

confidence: 99%

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Universal spectral shape of high accretion rate AGN

Nikołajuk

Różáńska

Dumont

2004

Nuclear Physics B - Proceedings Supplements

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Abstract. The spectra of quasars and NLS1 galaxies show surprising similarity in their spectral shape. They seem to scale only with the accretion rate. This is in contradiction with the simple expectations from the standard disk model which predicts lower disk temperature for higher black hole mass. Here we consider two mechanisms modifying the disk spectrum: the irradiation of the outer disk due to the scattering of the flux by the extended ionized medium (warm absorber) and the development of the warm Comptonizing disk skin under the effect of the radiation pressure instability. Those two mechanisms seem to lead to a spectrum which indeed roughly scales, as observed, only with the accretion rate. The scenario applies only to objects with relatively high luminosity to the Eddington luminosity ratio for which disk evaporation is inefficient.

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Active Galactic Nuclei

COLLIN‐ZAHN

2022

Active Galactic Nuclei

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A two-phase model for the X-ray emission from Seyfert galaxies

Cited by 993 publications

References 0 publications

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658

Universal spectral shape of high accretion rate AGN

Active Galactic Nuclei

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