5-GHz MERLIN and VLBA observations of compact 9C sources |
| |
| Authors: | R C Bolton C J Chandler G Cotter T J Pearson G G Pooley A C S Readhead J M Riley E M Waldram |
| |
| Institution: | Cavendish Astrophysics, Department of Physics, Madingley Road, Cambridge CB3 0HE;National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801, USA;Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH;California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125, USA |
| |
| Abstract: | In this paper, we present subarcsecond resolution observations of 36 compact sources from the 15h region of the 15-GHz 9th Cambridge survey. These sources all have previously measured simultaneous continuum radio spectra spanning 1.4–43 GHz and we classify each source by fitting a quadratic function to its spectrum. Using the Multi-Element Radio-Linked Interferometer Network and the Very Long Baseline Array, both at 5 GHz, we resolve all six steep-spectrum objects and four of the 13 flat-spectrum objects. However, none of the 16 objects with convex spectra peaking above 2.5 GHz is resolved even at <3-mas resolution. These results, in combination with the findings of a 15-GHz variability study, suggest that emission from the high-frequency peaking objects is affected by relativistic beaming, and that these objects are not necessarily as young as the synchrotron self-absorption interpretation of their peak frequencies would imply. |
| |
| Keywords: | surveys galaxies: active radio continuum: general |
|
|
