2008A&A...492..411G


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.20CET09:54:45

2008A&A...492..411G - Astronomy and Astrophysics, volume 492, 411-417 (2008/12-3)

Structure function of the UV variability of Q0957+561.

GOICOECHEA L.J., SHALYAPIN V.N., GIL-MERINO R. and ULLAN A.

Abstract (from CDS):

We present a detailed structure function analysis of the UV variability of Q0957+561. From optical observations in the 2005-2007 seasons, we constructed normalized structure functions of the quasar luminosity at restframe wavelengths λ∼2100Å and λ∼2600Å. Old optical records (1995-1996 seasons) also allow the structure function to be obtained at λ∼2100Å, but 10 years ago in the observer's frame. These three structure functions are then compared to predictions of both simple and relatively sophisticated (incorporating two independent variable components) Poissonian models. We do not find clear evidence of a chromatic mechanism of variability. From the recent data, ∼100-d time-symmetric and ∼170-d time-asymmetric flares are produced at both restframe wavelengths. Taking into account measurements of time delays and the existence of an EUV/radio jet, reverberation is probably the main mechanism of variability. Thus, two types of EUV/X-ray fluctuations would be generated within or close to the jet and later reprocessed by the disc gas in the two emission rings, at λ∼2100Å and λ∼2600Å. The ∼100-d time-symmetric shots are also responsible for most of the ∼2100Å variability detected in the old experiment (10 years ago). However, there is no evidence of asymmetric shots in the old UV variability. If reverberation is the involved mechanism of variability, this could mean an intermittent production of high-energy asymmetric fluctuations. The old records are also consistent with the presence of very short-lifetime (∼10d) symmetric flares, which may represent additional evidence of time evolution. Despite these exciting findings, we cannot rule out the possibility of unfortunate gaps in the old light curves (or a relatively short monitoring period) and very short-timescale systematic noise. We also discuss the quasar structure that emerges from the variability scenario.

Abstract Copyright:

Journal keyword(s): gravitational lensing - black hole physics - quasars: general - quasars: individual: Q0957+561

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 QSO B0909+5312 QSO 09 13 01.031 +52 59 28.90   17.29 16.71     ~ 127 1
2 7C 095757.60+560823.00 QSO 10 01 20.6915852239 +55 53 55.595776916   17.16 16.95     ~ 687 3
3 QSO B0957+5608B QSO 10 01 20.8374436455 +55 53 49.543959298   17.16 16.95     ~ 262 1
4 QSO B1001+4127 QSO 10 04 34.9236085542 +41 12 42.771226567   19.14 19.03     ~ 164 1
5 NGC 5548 Sy1 14 17 59.5401093128 +25 08 12.600227883   14.35 13.73     ~ 2348 0
6 NAME MR 2251-178 Sy1 22 54 05.8858021308 -17 34 55.403006841   14.99 14.36 15.12   ~ 369 3
7 NGC 7469 Sy1 23 03 15.674 +08 52 25.28 12.60 13.00 12.34     ~ 1855 3

    Equat.    Gal    SGal    Ecl

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2020.01.20-09:54:45

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