ERRATUM: “THE FIFTH DATA RELEASE SLOAN DIGITAL SKY SURVEY/XMM-NEWTON QUASAR SURVEY” (2009, ApJS, 183, 17)

Young, M.; Elvis, M.; Risaliti, G.

doi:10.1088/0067-0049/185/1/250

Cited by 56 publications

(107 citation statements)

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“…This correlation is found to be L UV ∝ L β X , with β ranging, in most studies, from 1.2 to 1.6 (Avni & Tananbaum 1982Kriss & Canizares 1985;Anderson & Margon 1987;Wilkes et al 1994;Yuan et al 1998;Vignali et al 2003;Strateva et al 2005;Steffen et al 2006;Just et al 2007;Young et al 2009;Lusso et al 2010;Grupe et al 2010;Stalin et al 2010). This correlation provides a strong constraint on the physical processes at work, since it tells us that the fraction of power in the accretion disc corona, emitted in the X-rays, decreases/increases as a function of the accretion disc power (mainly emitted in the UV).…”

Section: The X-ray To Optical/uv Correlationmentioning

confidence: 95%

The optical-UV spectral energy distribution of the unabsorbed AGN population in theXMM-NewtonBright Serendipitous Survey

Marchese

Ceca

Caccianiga

et al. 2012

A&A

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Context. Active galactic nuclei (AGN) emit radiation over a wide range of wavelengths, with a peak of emission in the far-UV region of the electromagnetic spectrum, a spectral region that is historically difficult to observe. Aims. Using optical, GALEX UV, and XMM-Newton data we derive the spectral energy distribution (SED) from the optical/UV to X-ray regime of a sizeable sample of AGN. The principal motivation is to investigate the relationship between the optical/UV emission and the X-ray emission and provide bolometric corrections to the hard X-ray (2-10 keV) energy range, k bol , the latter being a fundamental parameter in current physical cosmology. Methods. We construct and study the X-ray to optical SED of a sample of 195 X-ray selected Type 1 AGN belonging to the XMM-Newton bright serendipitous survey (XBS). The optical-UV luminosity was computed using data from the Sloan Digital Sky Survey (SDSS), from our own dedicated optical spectroscopy and the satellite GALaxy evolution EXplorer (GALEX), while the X-ray luminosity was computed using XMM-Newton data. Because it covers a wide range of redshift (0.03 < z < ∼ 2.2), X-ray luminosities (41.8 < log L [2−10] keV < 45.5 erg/s) and because it is composed of "bright objects", this sample is ideal for this kind of investigation. Results. We confirm a highly significant correlation between the accretion disc luminosity L disc and the hard X-ray luminosity, where β = 1.18 ± 0.05. We find a very shallow dependence of k bol on the X-ray luminosity with respect to the broad distribution of values of k bol . We find a correlation between k bol and the hard X-ray photon index Γ 2−10 keV and a tight correlation between the optical-to-X-ray spectral index α ox and k bol , so we conclude that both Γ 2−10 keV and α ox can be used as a proxy for k bol .

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Section: The X-ray To Optical/uv Correlationmentioning

confidence: 95%

The optical-UV spectral energy distribution of the unabsorbed AGN population in theXMM-NewtonBright Serendipitous Survey

Marchese

Ceca

Caccianiga

et al. 2012

A&A

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“…Partial correlation tests show that while the primary driver of α ox is l opt , the Eddington ratio correlates strongly with α ox when l opt is taken into account, so accretion rate may help explain these results. We combine the α ox − l opt and Γ-L bol /L Edd relations to naturally explain two results: 1) the existence of the Γ − l x relation as reported in Young et al (2009) and 2) the lack of a Γ − l opt relation. The consistency of the optical/X-ray correlations establishes a more complete framework for understanding the relation between quasar emission mechanisms.…”

mentioning

confidence: 89%

“…Young et al (2009) describes the SDSS quasar selection and cross-correlation with the XMM-Newton archive, as well as the X-ray data reduction and spectral fitting. For the purposes of this paper, we exclude broad absorption line (BAL) and radio-loud (RL) quasars, as these are known to have different α ox distributions than typical, radio-quiet (RQ) quasars (Green & Mathur 1996;Young et al 2009). While Young et al (2009) used an incomplete BAL list (Shen et al 2008), this paper updates the BAL classification using the DR5 BAL catalog (Gibson et al 2009).…”

Section: The Samplementioning

confidence: 99%

The X-Ray Energy Dependence of the Relation Between Optical and X-Ray Emission in Quasars

Young

Elvis

Risaliti

2009

ApJ

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We develop a new approach to the well-studied anti-correlation between the optical-to-X-ray spectral index, α ox , and the monochromatic optical luminosity, l opt . By cross-correlating the SDSS DR5 quasar catalog with the XMM-Newton archive, we create a sample of 327 quasars with X-ray S/N > 6, where both optical and X-ray spectra are available. This allows α ox to be defined at arbitrary frequencies, rather than the standard 2500Å and 2 keV. We find that while the choice of optical wavelength does not strongly influence the α ox −l opt relation, the slope of the relation does depend on the choice of X-ray energy. The slope of the relation becomes steeper when α ox is defined at low (∼ 1 keV) X-ray energies. This change is significant when compared to the slope predicted by a decrease in the baseline over which α ox is defined. The slopes are also marginally flatter than predicted at high (∼ 10 keV) X-ray energies. Partial correlation tests show that while the primary driver of α ox is l opt , the Eddington ratio correlates strongly with α ox when l opt is taken into account, so accretion rate may help explain these results. We combine the α ox − l opt and Γ-L bol /L Edd relations to naturally explain two results: 1) the existence of the Γ − l x relation as reported in Young et al. (2009) and 2) the lack of a Γ − l opt relation. The consistency of the optical/X-ray correlations establishes a more complete framework for understanding the relation between quasar emission mechanisms. We also discuss two correlations with the hard X-ray bolometric correction, which we show correlates with both α ox and Eddington ratio. This confirms that an increase in accretion rate correlates with a decrease in the fraction of up-scattered disk photons.

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“…Here we take advantage of a new AGN sample, using more than 300 AGNs from the Fifth Data Release Sloan Digital Sky Survey/Xmm-Newton Quasar Survey (Young et al [2,45]). This sample contains three optical monochromatic luminosities and six x-ray monochromatic luminosities.…”

Section: B Defining Our Agn Samplesmentioning

confidence: 99%

“…We consider also a further cut on the effective x-ray power-law photon index À (column 10 in Table II of Young et al [45]). The photon spectral index is defined as: À ¼ À þ 1, where À is the exponent obtained by fitting the x-ray part of the AGN spectrum with a single power-law model.…”

Section: Removing Obscured Agnsmentioning

confidence: 99%

On the evidence for axionlike particles from active galactic nuclei

Pettinari

Crittenden

2010

Phys. Rev. D

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Burrage, Davis, and Shaw [1] recently suggested exploiting the correlations between high and low energy luminosities of astrophysical objects to probe possible mixing between photons and axionlike particles (ALP) in magnetic field regions. They also presented evidence for the existence of ALP's by analyzing the optical/UV and x-ray monochromatic luminosities of active galactic nuclei. We extend their work by using the monochromatic luminosities of 320 unobscured active galactic nuclei from the Sloan Digital Sky Survey/Xmm-Newton Quasar Survey [2] which allows the exploration of 18 different combinations of optical/UV and x-ray monochromatic luminosities. However, we do not find compelling evidence for the existence of ALPs. Moreover, it appears that the signal reported by Burrage et al. is more likely due to x-ray absorption rather than to photon-ALP oscillation.

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ERRATUM: “THE FIFTH DATA RELEASE SLOAN DIGITAL SKY SURVEY/XMM-NEWTON QUASAR SURVEY” (2009, ApJS, 183, 17)

Cited by 56 publications

References 0 publications

The optical-UV spectral energy distribution of the unabsorbed AGN population in theXMM-NewtonBright Serendipitous Survey

The optical-UV spectral energy distribution of the unabsorbed AGN population in theXMM-NewtonBright Serendipitous Survey

The X-Ray Energy Dependence of the Relation Between Optical and X-Ray Emission in Quasars

On the evidence for axionlike particles from active galactic nuclei

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