Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2011-09-16
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
12 pages, 8 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics. Language improved, typos corrected
Scientific paper
10.1051/0004-6361/201117245
We study the photocenter position variability due to variations in the quasar inner structure. We consider variability in the accretion disk emissivity and torus structure variability due to different illumination by the central source. We discuss possible detection of these effects by Gaia. Observations of the photocenter variability in two AGNs, SDSS J121855+020002 and SDSS J162011+1724327 have been reported and discussed. With investigation of the variations in the quasar inner structure we explore how much this effect can affect the position determination and whether it can be (or not) detected with Gaia mission. We used (a) a model of a relativistic disk, including the perturbation that can increase brightness of a part of the disk, and consequently offset the photocenter position, and (b) a model of a dusty torus which absorbs and re-emits the incoming radiation from accretion disk. We estimated the value of the photocenter offset due to these two effects. We found that perturbations in the inner structure can significantly offset the photocenter. It depends on the characteristics of perturbation and accretion disk and structure of the torus. In the case of two considered QSOs the observed photocenter offsets cannot be explained by variations in the accretion disk and other effects should be considered. We discussed possibility of exploding stars very close to the AGN source, and also possibility that there are two variable sources in the center of these two AGNs that may indicate a binary super-massive black hole system on a kpc (pc) scale. The Gaia mission seems to be very perspective, not only for astrometry, but also for exploring the inner structure of AGNs. We conclude that variations in the quasar inner structure can affect the observed photocenter (up to several mas). There is a chance to observe such effect in the case of bright and low-redshifted QSOs.
Andrei Alexandre H.
Antón Sonia
Baes Maarten
Jovanović Predrag
Kovacevic Jelena
No associations
LandOfFree
Photo-centric variability of quasars caused by variations in their inner structure: Consequences on Gaia measurements does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Photo-centric variability of quasars caused by variations in their inner structure: Consequences on Gaia measurements, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photo-centric variability of quasars caused by variations in their inner structure: Consequences on Gaia measurements will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-535306