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E. J. Guerra (Rowan University), S. T. Myers (NRAO), R. B. Partridge, J. E. Cabanela (Haverford College)
While radio sources with spectra that peak at frequencies higher than 5-10 GHz are known, there is no systematic or reliable survey of such sources. They are intrinsically interesting as a potential class of ''young'' radio-loud AGN, a highly variable set of gravitational lens candidates, and a major component of foreground contamination in searches for cosmic microwave background fluctuations; hence such a survey is desirable. One means of detecting such sources is single-epoch, multi-frequency, observations of a set of sources which appear to have rising spectra ( \alpha > +0.4) between 1.4 and 4.8 GHz. Single-epoch observations are crucial for these sources, since they are very likely to be variable.
Results are presented from a September 2001 observing campaign at the Very Large Array to measure single-epoch radio spectra of 235 inverted-spectrum radio sources. Sources were selected from the cross-correlation of the VLA FIRST and GB6 catalogs to have inverted spectra (\alpha > +0.4) and single VLA FIRST detections within the GB6 beam. Spectra up to 23 GHz (K band) will be presented.
Lower limits on source counts at 23 GHz will be compared to model predictions of inverted-spectrum radio sources. These data can be used to refine estimates of the contribution of radio point sources to the foreground of CMB anisotropy experiments, both ground based and satellite-borne. Also, variable sources detected in this program will require follow-up observations with a particular emphasis on discovering gravitational lenses and contraining models of ''young'' AGN.
This work funded in part by National Science Foundation and the College of Liberal Arts and Sciences at Rowan University.