Spitzer 70 Micron Source Counts in GOODS-North
Abstract
We present ultradeep Spitzer 70 μm observations of GOODS-North (Great Observatories Origins Deep Survey). For the first time, the turnover in the 70 μm Euclidean-normalized differential source counts is observed. We derive source counts down to a flux density of 1.2 mJy. From the measured source counts and fluctuation analysis, we estimate a power-law approximation of the faint 70 μm source counts of dN/dS~S-1.6, consistent with that observed for the faint 24 μm sources. An extrapolation of the 70 μm source counts to zero flux density implies a total extragalactic background light (EBL) of 7.4+/-1.9 nW m-2 sr-1. The source counts above 1.2 mJy account for about 60% of the estimated EBL. From fluctuation analysis, we derive a photometric confusion level of σc=0.30+/-0.15 mJy (q=5) for the Spitzer 70 μm band.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2006
- DOI:
- 10.1086/507149
- arXiv:
- arXiv:astro-ph/0606676
- Bibcode:
- 2006ApJ...647L...9F
- Keywords:
-
- Cosmology: Observations;
- Galaxies: Evolution;
- Galaxies: High-Redshift;
- Infrared: Galaxies;
- Astrophysics
- E-Print:
- 6 pages including 2 figures and 1 table. Accepted ApJ Letters