Spitzer Space Telescope - General Observer Proposal #60173


Fossil Hunting: Intracluster Stars in Virgo

Principal Investigator: Eric Murphy
           Institution: Spitzer Science Center

     Technical Contact: Jessica Krick, California Institute of Technology

Co-Investigators: 
Jessica Krick, Spitzer Science Cener                                  
Vandana Desai, Spitzer Science Center                                 
Carrie Bridge, Spitzer Science Center                                 
Jason Surace, Spitzer Science Center                                  
Jeffrey Kenney, Yale University                                       
Jacqueline van Gorkom, Columbia University                            

Science Category: galaxy clusters and groups(low-z) 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 100.0 

Abstract:
In dense clusters, galaxy interactions and mergers play a significant role in
galaxy evolution. During these interactions, tidal forces can lead to the
ejection of stars from their parent galaxies; these stars are a fossil record of
environmentally-driven galaxy evolution. We propose to map the intracluster
light (ICL) at 3.6 and 4.5um using IRAC over a square degree near the Virgo
cluster core previously mapped in V-band by Mihos et al. (2005). While this
study has illuminated the wealth and complexity of stellar structures in Virgo's
core, the addition of IRAC data will allow us, for the first time, to: 1)
accurately measure the stellar mass of the intracluster stars (ICS),
constraining chemical enrichment models; 2) measure the colors of the ICS to
constrain the relative ages and origins of the ICS structures; 3) identify and
characterize the stellar counterparts of recently discovered gas filaments; and
4) make detailed comparisons between the atomic gas and stellar mass
distribution of the cluster core, thereby providing a benchmark for cosmological
simulations that trace structure formation. This program will help to elucidate
our understanding of how cluster galaxies evolve, and how the ICM is affected by
the removal of stars, metals, gas, and dust from in-falling galaxies.