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Star Formation in High Redshift Clusters with Spitzer
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We propose to study the evolution of star formation in galaxy cluster environments by
making measurements at epochs between 0.54 < z < 0.63. We will measure the integrated
SFRs for three optically selected galaxy clusters from the ESO Distant Cluster Survey
(EDisCS) using MIPS 24µm photometry. We will measure total past SFRs, i.e.
stellar masses, from rest-frame near-infrared (near-IR) photometry obtained with IRAC.
Two of the three galaxy clusters already have IRAC data. We propose taking new IRAC
data for CL1232.5-1250 to complete the set. We have found that H..-derived starformation
rates depend on both cluster mass and redshift,
demonstrating the necessity of sampling a large range in mass to disentangle evolutionary
trends from trends in mass. Our three targeted clusters span the range in mass from neargroup
environment to the most massive cluster in the EDisCS sample. This mass range
fills the gaps in existing studies, which are dominated by studies of field environments or
of very massive clusters.
The Spitzer MIPS 24µm observations are needed to make a comprehensive measurement
of the star formation rates in galaxies, because extinction by dust can completely obscure
the majority of star formation in galaxies. The IRAC observations will determine if AGN
activity is present in individual galaxies, which would bias our measures of the SFR
based on the 24µm flux since the AGN could also heat dust seen at 24µm. The IRAC
data will also provide robust stellar masses to quantify the total past star formation.
We will observe the central 5’x5’ of each cluster with MIPS in 24µm and with IRAC in
all four channels. Our 24µm observations will reach a sensitivity of one solar mass per
year and our IRAC depth is chosen to match the same SFR sensitivity.
Extensive ancillary data are already in hand, i.e. deep VRIJK imaging, 8-meter telescope
spectroscopy, HST I-band imaging for all three clusters, and IRAC data on two of the
clusters. This ancillary data will help to isolate cluster members and interpret the derived
SFRs. The mass and redshift range of our targets serves as an important complement to
other Spitzer studies of low and intermediate-redshift clusters and will provide a more
comprehensive picture of the evolution of star formation in galaxy clusters from z .. 1 to
z .. 0.
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Lead Teacher:
John Blackwell
Phillips Exeter Academy,
Exeter, NH
Participating Teachers:
Velvet Dowdy
Graves County High School, Mayfield, KY
Rosa Hemphill
Oregon Episcopal School, Portland, OR
Ardis Herrold
Grosse Pointe North High School, Grosse Pointe, MI
Thomas Loughran
Saint Joseph’s High School (SJHS), South Bend, IN
Dwight Taylor
South Anchorage High School, Anchorage, AK
Support Scientists:
Gregory Rudnick
National Optical Astronomical Observatory, Tucson, AZ
Rose Finn
Siena College, Loudonville, NY
Vandana Desai
Calfornia Institute of Technology, Pasadena, CA
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Program News
Proposal - pdf file
AOR
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