Short time-scale AGN X-ray variability with EXOSAT: black hole mass and normalized variability amplitude
نویسندگان
چکیده
منابع مشابه
The scaling of the X–ray variability with black hole mass in AGN
The relation between the 2− 10 keV, long term, excess variance and AGN black hole mass is considered in this work. A significant anti-correlation is found between these two quantities in the sense that the excess variance decreases with increasing black hole mass. This anti-correlation is consistent with the hypothesis that the 2− 10 keV power spectrum in AGN follows a power law of slope −2 at ...
متن کاملIs the anti - correlation between the X - ray variability amplitude and black hole mass of AGNs intrinsic ? ( Research Note )
Aims. Both the black hole mass and the X-ray luminosity of AGNs have been found to be anti-correlated with the normalized excess variance (σrms) of the X-ray light curves. We investigate which correlation with σ 2 rms is the intrinsic one. Methods. We divide a full sample of 33 AGNs (O’ Neill et al. 2005) into two sub-samples. The black hole masses of 17 objects in sub-sample 1 were determined ...
متن کاملHard X-ray Variability of AGN
Aims. Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods. The first 9 months of the Swift/BAT all-sky survey are used to study the 14 – 195 keV variability of the 44 brightest AGN. The sources have been selected due to their detection significance of > 10σ. We test...
متن کاملX-ray Variability of Agn and Correlations with Spectral Properties
Rapid flux changes in the X-ray emission from active galactic nuclei are commonly observed. The powerdensity spectra show a pseudo power-law form with a turnover at low frequencies and a high frequency break, similar to galactic black-hole candidates. There have been a few claims for periodicities but these are not a well-established property of the class. The amplitude of variability depends o...
متن کاملLetter to the Editor Correlation between variability time scale and X-ray spectral index in AGN
We have analysed EXOSAT ME X-ray light curves of a sample of AGN assuming a stochastic process in these sources. The result is a significant anti-correlation between the relaxation timescale τ , derived from this stochastic model fit, and the photon index Γ of the X-ray spectrum. This establishes for the first time a relationship between variability properties and spectral properties of the emi...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society: Letters
سال: 2013
ISSN: 1745-3933,1745-3925
DOI: 10.1093/mnrasl/sls048