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	XMM-Newton view of PKS 2155-304: Characterizing the X-ray variability properties with EPIC pn
	Zhang, YH ; Treves, A ; Celotti, A ; Qin, YP ; Bai, JM
	2010-05-06 ; 2010-05-06
关键词	BL Lacertae objects : general BL Lacertae objects : individual ( PKS 2155-304) galaxies : active methods : data analysis X-rays : galaxies ACTIVE GALACTIC NUCLEI BLACK-HOLE MASSES BL-LACERTAE OBJECTS SEYFERT 1 GALAXIES HOST GALAXIES SPECTRAL VARIABILITY TIME-SERIES TEV BLAZARS NARROW-LINE LONG Astronomy & Astrophysics
中文摘要	Starting from XMM-Newton EPIC pn data, we present the X-ray variability characteristics of PKS 2155-304 using a simple analysis of the excess variance, sigma(2)(XS), and of the fractional rms variability amplitude, F-var. The scatter in sigma(2)(XS) and F-var, calculated using 500 s long segments of the light curves, is smaller than the scatter expected for red-noise variability. This alone does not imply that the underlying process responsible for the variability of the source is stationary, since the real changes of the individual variance estimates are possibly smaller than the large scatters expected for a red-noise process. In fact, the averaged sigma(2)(XS) and F-var, which reduce the fluctuations of the individual variances, also change with time, indicating nonstationary variability. Moreover, both the averaged sigma(XS) ( absolute rms variability amplitude) and the averaged F-var show linear correlation with source flux, but in an opposite sense: sigma(XS) correlates with flux, but F-var anticorrelates with flux. These correlations suggest that the variability process of the source is strongly nonstationary, as random scatters of variances should not yield any correlation. Spectra of F-var were constructed to compare variability amplitudes in different energy bands. We found that the fractional rms variability amplitude of the source, when significant variability is observed, increases logarithmically with the photon energy, indicating significant spectral variability. The point-to-point variability amplitude may also track this trend, suggesting that the slopes of the power spectral density of the source are energy-independent. Using the normalized excess variance, the black hole mass of PKS 2155-304 was estimated to be about 1.45x10(8) M-circle dot. This is compared and contrasted with the estimates derived from measurements of the host galaxies.
语种	英语 ; 英语
出版者	UNIV CHICAGO PRESS ; CHICAGO ; 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/14944]
专题	清华大学
推荐引用方式 GB/T 7714	Zhang, YH,Treves, A,Celotti, A,et al. XMM-Newton view of PKS 2155-304: Characterizing the X-ray variability properties with EPIC pn[J],2010, 2010.
APA	Zhang, YH,Treves, A,Celotti, A,Qin, YP,&Bai, JM.(2010).XMM-Newton view of PKS 2155-304: Characterizing the X-ray variability properties with EPIC pn..
MLA	Zhang, YH,et al."XMM-Newton view of PKS 2155-304: Characterizing the X-ray variability properties with EPIC pn".(2010).

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