Open Access5‐GHz MERLIN and VLBA observations of compact 9C sources
Author(s) -
Bolton R. C.,
Chandler C. J.,
Cotter G.,
Pearson T. J.,
Pooley G. G.,
Readhead A. C. S.,
Riley J. M.,
Waldram E. M.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09952.x
Subject(s) - physics , astrophysics , merlin (protein) , spectral line , radio spectrum , interferometry , resolution (logic) , very long baseline array , synchrotron , very long baseline interferometry , angular resolution (graph drawing) , astronomy , optics , active galactic nucleus , galaxy , medicine , cancer , suppressor , mathematics , artificial intelligence , combinatorics , computer science
In this paper, we present subarcsecond resolution observations of 36 compact sources from the 15 h 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.