Mathematics – Logic
Scientific paper
May 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993aas...182.4407t&link_type=abstract
American Astronomical Society, 182nd AAS Meeting, #44.07; Bulletin of the American Astronomical Society, Vol. 25, p.868
Mathematics
Logic
Scientific paper
We present preliminary results from the second Caltech-Jodrell Bank VLBI survey (CJ2). This is a Mark 2 snapshot VLBI survey of flat- and peaked-spectrum sources. The CJ2 survey extends the morphological study of the Pearson & Readhead (1988, ApJ, 328, 114 and Pearson et al. 1993, these proceedings -- hereafter PR) and Caltech-Jodrell Bank (Xu et al. 1992, BAAS, 24, 1300 hereafter CJ) surveys to 400 sources. The CJ2 survey has three new cosmological goals: 1) to populate the proper motion--redshift diagram for superluminal sources; 2) to populate the size--redshift diagram for compact sources (both diagrams can be used to estimate the deceleration parameter, q_0); and 3) to search for small-separation gravitationally-lensed systems and hence to look directly for mass concentrations in the unexplored range of 10(6) - 10(9) \solmass. We expect this survey, like the previous large VLBI surveys, will reveal 5-10% of the sources to be interesting, unusual objects worth further study. The CJ2 sample is drawn from the Patnaik et al. (1992, MNRAS, 254, 655) list of ~ 900 compact flat-spectrum sources north of delta = 35° with 6 cm flux densities greater than 200 mJy. We have selected the strongest 200 of these sources subject to the further criteria that they are out of the galactic plane (|b| > 10°), flat-spectrum (alpha flatter than -0.5), and have not been previously observed in the PR or CJ surveys. So far 76 sources have been successfully imaged at 6 cm with ~ 1 mas resolution and a typical dynamic range of 500:1. The vast majority (63/76) of these sources have core-jet morphologies and are therefore well suited for the cosmological tests described above. Roughly 12% (9/76) are candidate compact symmetric (CS) sources. This group of sources is not well understood and is of considerable current interest (Readhead et al. 1993, these proceedings).
Browne Ian W. A.
Cohen Morrel H.
Henstock D. R.
Patnaik Alok
Pearson Timothy. J.
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