2011A&A...536A..84V


Query : 2011A&A...536A..84V

2011A&A...536A..84V - Astronomy and Astrophysics, volume 536A, 84-84 (2011/12-1)

Ensemble X-ray variability of active galactic nuclei from serendipitous source catalogues.

VAGNETTI F., TURRIZIANI S. and TREVESE D.

Abstract (from CDS):

The X-ray variability of the active galactic nuclei (AGN) has been most often investigated with studies of individual, nearby sources, and only a few ensemble analyses have been applied to large samples in wide ranges of luminosity and redshift. We aim to determine the ensemble variability properties of two serendipitously selected AGN samples extracted from the catalogues of XMM-Newton and Swift, with redshift between ∼0.2 and ∼4.5, and X-ray luminosities, in the 0.5-4.5keV band, between ∼1043erg/s and ∼1046erg/s. We used the structure function (SF), which operates in the time domain, and allows for an ensemble analysis even when only a few observations are available for individual sources and the power spectral density (PSD) cannot be derived. The SF is also more appropriate than fractional variability and excess variance, because these parameters are biased by the duration of the monitoring time interval in the rest-frame, and therefore by cosmological time dilation. We find statistically consistent results for the two samples, with the SF described by a power law of the time lag, approximately as SF∝τ0.1. We do not find evidence of the break in the SF, at variance with the case of lower luminosity AGNs. We confirm a strong anti-correlation of the variability with X-ray luminosity, accompanied by a change of the slope of the SF. We find evidence in support of a weak, intrinsic, average increase of X-ray variability with redshift. The change of amplitude and slope of the SF with X-ray luminosity provides new constraints on both single oscillator models and multiple subunit models of variability.

Abstract Copyright:

Journal keyword(s): surveys - galaxies: active - quasars: general - X-rays: galaxies

VizieR on-line data: <Available at CDS (J/A+A/536/A84): table1.dat table2.dat>

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 24

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Number of rows : 24
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 GRB 050904 gB 00 54 50.794 +14 05 09.42           ~ 450 0
2 GRB 060908 gB 02 07 18.360 +00 20 31.20 16.99 18.34 16.85     ~ 189 0
3 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 1970 1
4 GRB 070125 gB 07 51 17.80 +31 09 04.8           ~ 167 0
5 GRB 051227 gB 08 20 58.107 +31 55 32.01           ~ 115 0
6 GRB 051016B gB 08 48 27.810 +13 39 20.00 20.45         ~ 134 0
7 GRB 050505 gB 09 27 03.300 +30 16 23.70     20.74     ~ 183 0
8 GRB 060108 gB 09 48 01.980 +31 55 08.59           ~ 98 0
9 GRB 050319 gB 10 16 47.900 +43 32 53.80   18.02 17.01     ~ 249 0
10 NAME Lockman Hole reg 10 45 00.0 +58 00 00           ~ 793 0
11 GRB 050215B gB 11 37 48.030 +40 47 43.39           ~ 65 0
12 GRB 060319 gB 11 45 33.050 +60 00 39.61 20.10         ~ 63 0
13 GRB 050408 gB 12 02 17.320 +10 51 10.00           ~ 146 0
14 GRB 070419A gB 12 10 58.830 +39 55 34.06 18.52         ~ 114 0
15 GRB 060712 gB 12 16 16.170 +35 32 17.70           ~ 34 0
16 GRB 050520 gB 12 50 05.770 +30 27 02.30           ~ 37 0
17 GRB 070406 gB 13 15 51.350 +16 30 46.90 20.54         ~ 46 0
18 GRB 051008 gB 13 31 28.100 +42 08 05.01 17.06   14.11     ~ 77 0
19 GRB 060204B gB 14 07 14.900 +27 40 36.40           ~ 81 0
20 GRB 060801 gB 14 12 01.290 +16 58 54.00           ~ 149 0
21 GRB 050802 gB 14 37 05.820 +27 47 12.62 16.85 17.38 16.97     ~ 166 0
22 GRB 060805A gB 14 43 43.480 +12 35 11.40           ~ 55 0
23 GRB 060219 gB 16 07 21.520 +32 18 57.59           ~ 46 0
24 GRB 060807 gB 16 50 02.600 +31 35 30.70           ~ 54 0

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2022.09.24-19:34:23

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