An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649

Details An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649 An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649

Aug 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003aj....126..723t&link_type=abstract

The Astronomical Journal, Volume 126, Issue 2, pp. 723-733.

Astronomy and Astrophysics

Astronomy

9

Galaxies: Active, Galaxies: Individual (Pks 1718-649), Radio Continuum

Scientific paper

We have undertaken the most detailed investigation yet of the shape and variability of the radio spectrum near the spectral peak of a gigahertz-peaked spectrum radio galaxy, using the Australia Telescope Compact Array. The radio spectrum of PKS 1718-649 was measured nearly simultaneously at 30-40 different frequencies over the range of 1-9 GHz at four epochs over a 14 month period, with the aim of constraining different physical models for the absorption process that causes the spectral peak at gigahertz frequencies. We find that the two most plausible absorption processes, synchrotron self-absorption and free-free absorption, can each explain most aspects of the data. However, each process also has difficulty explaining some aspects of the data, in particular the variability of the source at frequencies below the peak. In either case, models based on homogeneous absorbers are clearly inadequate and inhomogeneities must be introduced into either the synchrotron self-absorbed source or the free-free absorbing screen. Based on our analysis we cannot strongly prefer either synchrotron self-absorption or free-free absorption as the sole process responsible for the gigahertz-peaked spectrum of PKS 1718-649. However, the consistency of the measured source size, from VLBI observations, with the observed turnover frequency favors synchrotron self-absorption as a significant effect in PKS 1718-649.

Affiliated with

Also associated with

No associations

Rating

An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649 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 An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An Investigation of Synchrotron Self-absorption and Free-Free Absorption Models in Explanation of the Gigahertz-peaked Spectrum of PKS 1718-649 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1663487