Spitzer Space Telescope - Archive Research Proposal #50640


Study of Galaxy Counts and Stellar Excesses in IRS Peak-Up Archival Observations

Principal Investigator: Sergio Fajardo-Acosta
           Institution: Spitzer Science Center

     Technical Contact: Sergio Fajardo-Acosta, Spitzer Science Center

Co-Investigators: 
Harry Teplitz, Spitzer Science Center                                 
James Colbert, Spitzer Science Center                                 
Lee Armus, Spitzer Science Center                                     
Vassilis Charmandaris, University of Crete                            

Science Category: high-z galaxies (z>0.5) 
Dollars Approved: 75000 

Abstract:
The IRS Peak-Up arrays are read out in parallel to every Short-Low spectrum
taken during the Spitzer mission. We propose to mine this extensive set of more
than 170,000 Peak-Up images, which are amply distributed across the sky. We
propose to use these images for two main programs: (i) to study galaxy counts in
moderately deep 16 micron images over a wide area; and (ii) to search for
infrared excesses from stars. The 16 micron Peak-Up images include almost a
square degree of low-background data at exposure times of at least 100 sec. Of
these, about 300 square arcmin have exposure times greater than 15 minutes.
These data will include 5,000--10,000 galaxies with 16-micron flux densities >
120 micro-Jy. This deep survey is unique because such coverage cannot be
achieved in dedicated pointed observations, due to the small Peak-Up field of
view. The IRS Peak-Up blue and red filters sample the SEDs of stellar sources at
16 and 22 microns. The stellar systems we will study are main-sequence and
evolved stars. We expect to detect at least several hundred stars in the Peak-Up
images, and expect to find excesses in about 10% of main-sequence stars, plus a
higher percentage of dust shells around evolved stars. The intended goal of this
study is the detection of new and unique phenomenology in main-sequence and
evolved stars. We propose to release catalogs of point sources, as added-value
products for the community. Through this program we will expand the impact of
Spitzer observations for ancillary discoveries.