Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009aas...21333202d&link_type=abstract
American Astronomical Society, AAS Meeting #213, #332.02; Bulletin of the American Astronomical Society, Vol. 41, p.392
Astronomy and Astrophysics
Astronomy
Scientific paper
A minority of quasars have luminous radio emission, yet radio observations have led to many important quasar discoveries. The VLA FIRST survey, covering nearly a quarter of the sky at 20cm with milliJy sensitivity, has proven to be a highly useful tool for identifying quasars, often uncovering those missed by optical selection techniques.
This includes the only z>6 radio-loud quasar known to date, J1427+3312, which we found by examining FIRST counterparts in the NOAO Deep Wide Field Survey (NDWFS) and the FLAMEX infrared survey, a combined region of only 4 square degrees of sky. I will discuss the implications this discovery has on understanding the high-redshift quasar population. Further observations with the VLA at 8GHz show that J1427+3312 has a steep spectrum (alpha=-1.1), while 1.4GHz VLBA observations resolve it into several components, most prominently two radio lobes separated by 170pc. These results suggest that J1427+3312 is a Compact Symmetric Object, with an implied dynamical age of only 1000 years.
Finally, I will present results from a spectrographic survey designed to find z>3.5 radio-loud quasars using FIRST and SDSS. Selecting red stellar sources from SDSS having FIRST counterparts within 0.5'' leads to a high discovery rate for distant quasars. Out of a sample of 40 targets, we have identified 7 new z>3.5 quasars, with the highest redshift source at z=4.85.
Duff McGreer Ian
Helfand David J.
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