Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM–Newton: spectral energy distributions for the reverberation mapped sample

By R. Vasudevan, A. C. Fabian. 2008

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We employ contemporaneous optical, ultraviolet (UV) and X-ray observations from the XMM–Newton European Photon Imaging Camera (EPIC-pn) and Optical Monitor (OM) archives to present, for the first time, simultaneous spectral energy distributions (SEDs) for the majority of the Peterson et al. reverberation mapped sample of active galactic nuclei (AGN). The raw data were reduced using the latest pipelines and are all analysed consistently. The virial mass estimates from Peterson et al. allow us to calculate Eddington ratios λEdd for the sample using the bolometric accretion luminosities determined directly from the SEDs. We calculate hard X-ray bolometric corrections κ2–10 keV for the sample and confirm a trend for increasing bolometric correction with Eddington ratio proposed in previous studies. Our comparison with previous work on these objects suggests that the OM bandpass may be less susceptible to intrinsic reddening than the far-UV peak of the thermal disc spectrum in AGN, yielding larger bolometric corrections than previous work: κ2–10 keV≈ 15–30 for λEdd≲ 0.1, κ2–10 keV≈ 20–70 for 0.1 ≲λEdd≲ 0.2 and κ2–10 keV≈ 70–150 for λEdd≳ 0.2, but part of this increase could be attributed to spectral complexity preventing accurate recovery of the intrinsic luminosity in some sources. Long-term optical–UV variability contributes a second order, but significant change to the total bolometric luminosity when comparing multiple observations for individual objects. We also consider the effect of a recently proposed correction for radiation pressure when determining black hole masses with reverberation mapping, and find that the revised mass estimates do not significantly alter the range of bolometric corrections seen but may yield a narrower distribution of Eddington ratios.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/baf95583a88ca7f127cac2807947bb7388e9f135

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Citations in the corpus

A global look at X-ray time lags in seyfert galaxies (2016, methodology): “The Eddington ratio was calculated using the bolometric luminosities calculated from the SEDs in Vasudevan & Fabian (2007, 2009); Vasudevan et al. (2010), and Wang et al. (2004).”
THE SIMULTANEOUS OPTICAL-TO-X-RAY SPECTRAL ENERGY DISTRIBUTION OF SOFT X-RAY SELECTED ACTIVE GALACTIC NUCLEI OBSERVED BY SWIFT (2010, methodology): “Recently, Vasudevan & Fabian (2009a) presented the bolometric corrections for 29 AGN with simultaneous optical/UV and X-ray observations from the XMM-Newton OM and EPIC pn and Vasudevan et al. (2009b) presented a sample of 26 AGN selected from the 9 months Swift BAT survey (Markwardt et al. 2005;…”
THE CORES OF THE Fe Kα LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE (2010, methodology): “As a proxy for the accretion rate we use the ratio of L2–10 keV/LEdd (see, e.g., Vasudevan & Fabian 2009 for the correspondence between and X-ray luminosity and bolometric luminosity).”
What drives the growth of black holes (2011, background): “However, since AGNs vary significantly in the X-ray band, contemporous X-ray and UV-optical data are required to account for intrinsic variations (e.g., Vasudevan & Fabian, 2009).”
The origin of the broad line region in active galactic nuclei (2010, methodology): “We also calculated the ionizing flux for all of these sources, using the broad-band spectrum from Vasudevan & Fabian (2009).”
Accretion-driven evolution of black holes: Eddington ratios, duty cycles and active galaxy fractions (2011, background): “In particular, Vasudevan & Fabian (2007, 2009) suggest that variations in the disc emission in the ultraviolet may be important to build the optical-to-X-ray spectral energy distributions of AGNs.”
Bolometric luminosities and Eddington ratios of X-ray selected active galactic nuclei in the XMM-COSMOS survey (2012, background): “That work showed that the bolometric parameters areuseful to give an indication of the accretion rate onto SMBH (i.e., alower bolometric correction corresponds to a lower Eddington ratio, nd vice-versa; see also Vasudevan & Fabian 2009; Vasudevan et al. 2009, hereafter V09a and V09b respectively).”
PRIMUS: THE DEPENDENCE OF AGN ACCRETION ON HOST STELLAR MASS AND COLOR (2011, background): “…of recent studies, however, have used observed multiband SEDs of unobscured AGNs to accurately measure bolometric luminosities and propose that k2−10keV may be more closely correlated with the Eddington ratio, albeit with significant scatter (Vasudevan & Fabian 2007, 2009; Lusso et al. 2010).”
Tracing the cosmic growth of supermassive black holes to z ∼ 3 with Herschel (2014, background): “Such an assumption relies on the fact that large kbol values have been found in hard X-rays, of the order of 20−30 (Risaliti & Elvis 2004; Marconi et al. 2004; Hopkins et al. 2007; Pozzi et al. 2007; Vasudevan & Fabian 2009; Lusso et al. 2012), increasing as a function of Lbol,AGN.7 In Fig.”
A physical model of the broad-band continuum of AGN and its implications for the UV/X relation and optical variability (2018, background): “…by a decrease in Rcorona/Rg (where Rg = GM/c2) correlated with a increase in the hot Comptonisation power law spectra index as Lbol/LEdd increases (Jin et al. 2012a,b; Ezhikode et al. 2017; see also Shemmer et al. 2006, 2008 and Vasudevan & Fabian 2007, 2009 for the hard X-ray spectral index).”
Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers (2012, methodology): “The bolometric luminosity Lbol is estimated as Lbol = kbolLion, where kbol≃10 (McKernan et al. 2007; Vasudevan & Fabian 2009; Lusso et al. 2010).”
The X-ray to optical-UV luminosity ratio of X-ray selected type 1 AGN in XMM-COSMOS (2009, background): “∗ Only extragalactic sources are considered. correctionkbol and Eddington ratioλEdd, recently obtained for bright AGN in the nearby Universe (Vasudevan & Fabian 2009; hereafter VF09), holds also at higher redshifts.”
First X-ray-based statistical tests for clumpy-torus models: eclipse events from 230 years of monitoring of Seyfert AGN (2014, methodology): “…to each cloud rcl can be derived from the cloud’s ion- 7 Values for LBol for most sources are taken from Vasudevan et al. (2010), except for Fairall 9 (Vasudevan & Fabian 2009), and MR 2251–178 and Cen A (L2−10 from Rivers et al. 2013 and LBol/L2−10 corrections from Marconi et al. 2004 for both…”
The Illustris simulation: the evolving population of black holes across cosmic time (2014, background): “…the bolometric and hard X-ray luminosity functions large uncertainties remain due to poorly constrained bolometric corrections (Hopkins et al. 2007; Vasudevan & Fabian 2007, 2009; Lusso et al. 2012) and the c© 0000 RAS, MNRAS 000, 000–000 uncertain fraction of Compton-thick sources for z & 0 (e.g.…”
Active galactic nuclei: what’s in a name? (2017, background): “7.1.1), thus the sampling of longer timescales also allows detection of variability over a wider range of MBH and L/LEdd.”
A Combined Optical and X-ray Study of Unobscured Type 1 AGN. I. Optical Spectra and SED Modeling (2011, methodology): “An obvious consequence is that in such studies a soft-excess component cannot influence the models, so making it possible to fit the data using just a disc and (broken) power-law continuum (VF07; Vasudevan & Fabian 2009).”