VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots

Details VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots

2011-07-04

arxiv.org/abs/1107.0719v3

Astronomy & Astrophysics 535 (2011) A24

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

34 pages, 8 figures, 2 tables, accepted to A&A

Scientific paper

10.1051/0004-6361/201015772

The Compact Symmetric Objects (CSOs) are small (<1 kiloparsec) and powerful extragalactic radio sources showing emission on both sides of an active galactic nucleus and no signs of strong relativistic beaming. They may be young radio sources, progenitors of large FRII radio galaxies. We aim to study the statistical properties of CSOs by constructing and investigating a new large sample of CSO candidates on the basis of dual-frequency, parsec-scale morphology. For the candidate selection we utilized VLBI data for 4170 extragalactic objects obtained simultaneously at 2.3 and 8.6 GHz (S and X band) within the VLBA Calibrator Survey 1-6 and the Research and Development - VLBA projects. Properties of their broad-band radio spectra were characterized by using RATAN-600 observations. Numerical modeling was applied in an attempt to explain the observed effects. A sample of 64 candidate CSOs is identified. The median two-point S-X band spectral index of parsec-scale hotspots is found to be -0.52; with the median brightness temperature ~10^9 K at X band. Statistical analysis reveals a systematic difference between positions of brightest CSO components (associated with hotspots) measured in the S and X bands. The distance between these components is found to be on average 0.32+/-0.06 mas greater at 8.6 GHz than at 2.3 GHz. This difference in distances cannot be explained by different resolutions at the S and X bands. It is a manifestation of spectral index gradients across CSO components, which may potentially provide important physical information about them. Despite our detailed numerical modeling of a CSO hotspot, the model was not able to reproduce the magnitude of the observed positional difference. A more detailed modeling may shed light on the origin of the effect.

Affiliated with

Also associated with

No associations

Rating

VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots 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 VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and VLBI-selected sample of Compact Symmetric Object candidates and frequency-dependent position of hotspots will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-5067