Proposal code
w036
Proposal title
Testing the cause of spectral turnovers in GPS sources
The |
Investigators and their |
Affiliations |
| P.I. |
A.G. Polatidis |
JIVE/Onsala Space Observatory, SWEDEN |
| |
J.E. Conway |
Onsala Space Observatory, SWEDEN |
| |
I. Oswanik |
Torun Center for Astronomy , Poland |
Proposal Abstract
Two general classes of models have been proposed to explain the cause
of the spectral break in GPS/CSO sources. In one of them, the
Synchrotron Self Absorption (SSA) model, the absorption is external
to the source. In the other model, Free-Free Absorption and Induced
Compton Scattering (FFA/ICS) are involved and the absorption is due
to external ionised gas from the surrounding interstellar
medium. Due to the different location of the absorbing component the
size of the source observed in the optically thin regime is expected
to be different than in the optically thick regime. In particular the
for the SSA model the observed image at low frequencies will be
larger than at high frequencies while the inverse is true for the
FFA/ICS model. We propose to observe 4 CSOs with HALCA at 18 cm to
compare with ground VLBI images at 6cm and to attempt to distinguish
which model applies to GPS sources.
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