Radio-optical outlier quasars - a case study with ICRF2 and SDSS

Details Radio-optical outlier quasars - a case study with ICRF2 and SDSS Radio-optical outlier quasars - a case study with ICRF2 and SDSS

2012-01-20

arxiv.org/abs/1201.4266v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

4 pages, 1 figure. To appear in the proceedings of the "QSO Astrophysics, Fundamental physics, and Astrometric Cosmology in th

Scientific paper

With Gaia, it will become possible to directly link the radio and optical reference frames using a large number of common objects. For the most accurate radio-optical link, it is important to know the level of spatial coincidence between the quasars' optical positions, and the radio positions determined by Very Long Baseline Interferometry (VLBI) observations. The "outlier" objects, for which the positions are significantly offset at the two different electromagnetic wavebands, may be of astrophysical interest as well. Here we present a case study to compare the radio positions of ~800 quasars common in the second realization of the International Celestial Reference Frame (ICRF2) and in the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) catalogue. Compared to the radio ICRF2, the SDSS provides two orders of magnitude less accurate astrometric data in the optical. However, its extensive sky coverage and faint magnitude limit allow us to directly relate the positions of a large sample of radio sources. This way we provide an independent check of the overall accuracy of the SDSS positions and confirm that the astrometric calibration of the latest Data Release 8 (DR8) is poorer than that of the DR7. We find over 20 sources for which the optical and radio brightness peaks are apparently not coincident at least at the 3-sigma level of SDSS DR7 positional accuracy, and briefly discuss the possible causes, including dual active galactic nuclei.

Affiliated with

Also associated with

No associations

Rating

Radio-optical outlier quasars - a case study with ICRF2 and SDSS 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 Radio-optical outlier quasars - a case study with ICRF2 and SDSS, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radio-optical outlier quasars - a case study with ICRF2 and SDSS will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-320723