Spitzer Space Telescope - General Observer Proposal #80025


Stellar Distributions in Dark Matter Halos: Looking Over the Edge

Principal Investigator: Liese van Zee
           Institution: Indiana University

     Technical Contact: Daniel Dale, University of Wyoming

Co-Investigators: 
Daniel A. Dale, University of Wyoming                                 
Kate L. Barnes, Indiana University                                    
Shawn Staudaher, University of Wyoming                                
Daniela Calzetti, University of Massachusetts                         
Julianne J. Dalcanton, University of Washington                       
James S. Bullock, University of California, Irvine                    
Rupali Chandar, University of Toledo                                  

Science Category: nearby galaxies (z<0.05, v_sys<15,000 km/s) 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 1005.3 

Abstract:
We propose to obtain deep observations with IRAC bands 1 and 2 to trace the
faint extended stellar component of nearby galaxies. Little is known about the
full extent of the stellar distribution in normal galaxies; deep IR observations
of the area around galaxies will allow us to trace the stellar distribution to
unprecedented levels. Our sample will include galaxies with a range of
morphology, inclination angle, luminosity, and environment in order to explore
fully the diverse range of galaxy properties and to enhance the legacy value of
this data set. These observations will enable a wide variety of projects,
including investigation of thick disks and halo formation, identification of old
and young star clusters, and identification of stars well beyond the bright
stellar disk. The proposed observations will provide not only a census, but also
the first quantitative measurements of the physical properties of low surface
brightness features identified around nearby galaxies (e.g., stellar mass
surface density, distribution, and fraction of total stellar mass). With
sensitivity to substructures featuring stellar mass surface densities of only a
few x 0.01 M_sun/pc^2, this project will provide the first look at the stellar
edge for a large sample of galaxies and will be instrumental in providing
observational constraints for galaxy formation models.