Search for Unresolved Sources in the COBE-DMR Two-Year Sky Maps
Abstract
We have searched the temperature maps from the COBE Differential Microwave Radiometers (DMR) first two years of data for evidence of unresolved sources. The high-latitude sky (|b| > 30^deg^) contains no sources brighter than 192 microK thermodynamic temperature (322 Jy at 53 GHz). The cumulative count of sources brighter than threshold T, N(> T), is consistent with a superposition of instrument noise plus scale- invariant spectrum of cosmic temperature fluctuations normalized to Q_rms-PS_ = 17 microK. We examine the temperature maps toward nearby clusters and find no evidence for any Sunyaev-Zel'dovich effect, {DELTA}y < 7.3 x 10^-6^ (95% CL) averaged over the DMR beam. We examine the temperature maps near the brightest expected radio sources and detect no evidence of significant emission. The lack of bright unresolved sources in the DMR maps, taken with anisotropy measurements on smaller angular scales, places a weak constraint on the integral number density of any unresolved Planck-spectrum sources brighter than flux density S, n(> S) < 2 x 10^4^ (S/1 Jy)^-2^ sr^-1^.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1994
- DOI:
- 10.1086/174655
- arXiv:
- arXiv:astro-ph/9402007
- Bibcode:
- 1994ApJ...433..435K
- Keywords:
-
- Astronomical Models;
- Radio Astronomy;
- Radio Sources (Astronomy);
- Sky Surveys (Astronomy);
- Temperature;
- Cosmic Background Explorer Satellite;
- Cross Correlation;
- Microwave Radiometers;
- Statistical Analysis;
- Astronomy;
- COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
- RADIO CONTINUUM: GENERAL;
- Astrophysics
- E-Print:
- 16 pages including 2 figures, uuencoded PostScript, COBE preprint 94-06