X-ray observations of 20 3CR radio galaxies and their environs

Feigelson, E. D.; Berg, Christopher

doi:10.1086/161051

Cited by 56 publications

(52 citation statements)

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“…However, not a single setup is able to yield the parameters similar to those of the fundamental plane, neither in term of correlation strength, nor in terms of linear regression slopes. In particular, as the correlation is only created by the flux limits, we find ξ RX ≈ 1, as it is expected given that we are simply plotting distance against distance (Feigelson and Berg, 1983). Also as expected, the flux limits have no effect on the mass term, and one therefore finds no mass dependence of the radio luminosity ξ RM ≈ 0.…”

Section: On the Effects Of Flux Limitssupporting

confidence: 81%

“…As discussed in the introduction, statistical tools exist to test whether a correlation is, in fact, an artifact of distance, or whether it reflects an underlying luminosity-luminosity relation, even in flux limited samples (Feigelson and Berg, 1983). In MHD03 (section 3) a partial correlation analysis was performed, including all upper limits in the sample using the algorithm for performing Kendall's τ test in the presence of censored data proposed by Akritas & Siebert (1996).…”

Section: The Fundamental Plane Of Black Hole Activitymentioning

confidence: 99%

“…In fact, the questions that arose in this discussion stimulated the formulation and the wider recognition of a set of statistical methods specifically targeted to astrophysical problems (see e.g. Feigelson and Berg 1983;Kembhavi, Feigelson and Singh 1986; for a comprehensive discussion of statistical methods and problems in astrophysics, see Babu and Feigelson 1996 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Why the fundamental plane of black hole activity is not simply a distance driven artifact

et al. 2006

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The fundamental plane of black hole activity is a non-linear correlation among radio core luminosity, X-ray luminosity and mass of all accreting black holes, both of stellar mass and supermassive, found by Merloni, Heinz and Di Matteo (2003) and, independently, by Falcke, Körding and Markoff (2004). Here we further examine a number of statistical issues related to this correlation. In particular, we discuss the issue of sample selection and quantify the bias introduced by the effect of distance in two of the correlated quantities. We demonstrate that the fundamental plane relation cannot be a distance artifact, and that its non-linearity must represent an intrinsic characteristic of accreting black holes. We also discuss possible future observational strategies to improve our understanding of this correlation.

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Section: On the Effects Of Flux Limitssupporting

confidence: 81%

Section: The Fundamental Plane Of Black Hole Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Why the fundamental plane of black hole activity is not simply a distance driven artifact

et al. 2006

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“…The study of correlations between outputs at different wavelengths is better done by directly comparing luminosities rather than fluxes, since any correlation in the luminosity space will be distorted in the flux space unless the luminosities are linearly correlated (Feigelson & Berg 1983;Padovani 1992). However, the use of luminosities instead of fluxes always introduces a redshift bias in flux limited samples, as luminosities are strongly correlated with redshift.…”

Section: Resultsmentioning

confidence: 99%

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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“…It is possible that it is in some measure created by the common dependence on redshift of the gamma and radio luminosities rather than their intrinsic correlation. Redshift bias and instrument flux limits are the two factors most likely to create spurious correlations (Elvis et al 1978;Feigelson & Berg 1983;Muecke et al 1997;Bloom 2008). In this study we have tried to alleviate their effect by including the upper limits in radio fluxes and luminosities and by using correlation tests taking the redshift bias into account.…”

Section: Flux Densities and Luminositiesmentioning

confidence: 99%

Correlation betweenFermi/LAT gamma-ray and 37 GHz radio properties of northern AGN averaged over 11 months

Nieppola

Tornikoski

Valtaoja

et al. 2011

A&A

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Aims. Although the Fermi mission has increased our knowledge of gamma-ray AGN, many questions remain, such as the site of gamma-ray production, the emission mechanism, and the factors that govern the strength of the emission. Using data from a high radio band, 37 GHz, uncontaminated by other radiation components besides the jet emission, we study these questions with averaged flux densities over the the first year of Fermi operations. Methods. We look for possible correlations between the 100 MeV-100 GeV band used by the Fermi satellite and 37 GHz radio band observed at the Aalto University Metsähovi Radio Telescope, as well as for differences between the gamma-ray emission of different AGN subsamples. We use data averaged over the 1FGL period. Our sample includes 249 northern AGN, including a complete sample of 68 northern AGN with a measured average flux density exceeding 1 Jy. Results. We find significant correlation between both the flux densities and luminosities in gamma and radio bands. The Fermi luminosity is inversely correlated with the peak frequency of the synchrotron component of the AGN spectral energy distributions. We also calculate the gamma dominances, defined as the ratio between the gamma and radio flux densities, and find an indication that high-energy blazars are more gamma-dominated than low-energy blazars. After studying the distributions of gamma and radio luminosities, it is clear that BL Lacertae objects are different from quasars, with significantly lower luminosities. It is unclear whether this is an intrinsic difference, an effect of variable relativistic boosting across the synchrotron peak frequency range, or the result of Fermi being more sensitive to hard spectrum sources like BL Lacertae objects. Our results suggest that the gamma radiation is produced co-spatially with the 37 GHz emission, i.e., in the jet.

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X-ray observations of 20 3CR radio galaxies and their environs

Cited by 56 publications

References 0 publications

Why the fundamental plane of black hole activity is not simply a distance driven artifact

Why the fundamental plane of black hole activity is not simply a distance driven artifact

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

Correlation betweenFermi/LAT gamma-ray and 37 GHz radio properties of northern AGN averaged over 11 months

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