Extragalactic abstracts - IRSA - California Institute of Technology

Spitzer_Approved_Extragalactic
Mar 25, 10 16:24 Page 583/742
Spitzer Space Telescope − General Observer Proposal #20754
The Stellar Mass of High Redshift RCS Galaxy Clusters
Principal Investigator: Erica Ellingson
Institution: University of Colorado
Technical Contact: Erica Ellingson, University of Colorado
Co−Investigators:
Howard Yee, University of Toronto
Michael Gladders, Carnegie Observatories
Kris Blindert, University of Toronto
Adam Muzzin, University of Toronto
Tracy Webb, Leiden Observatory
Henk Hoekstra, University of Victoria
David Gilbank, University of Toronto
Science Category: galaxy clusters and groups
Observing Modes: IracMap
Hours Approved: 15.3
Abstract:
We propose IRAC observations of a sample of 42 galaxy clusters at z>0.5 drawn
from the Red−Sequence Cluster Survey (RCS). These observations will be used to
calibrate the optical richness of clutsters in the RCS surveys to stellar mass.
Extensive multiwavelength observations of the sample will then allow us to
calculate the cluster mass function to z~1, providing important constraints on
the nature of dark energy and its effect on the formation on large scale
structure. We will also use these observations to form a stellar−mass limited
sample of cluster galaxies which will allow us to address outstanding questions
about the evolution of galaxies in dense cluster environments. In particular, we
will identify whether the well−known Butcher−Oemler effect is caused primarily
by normal star forming galaxies falling into the cluster, or by dwarf galaxies
undergoing strong starbursts within the cluster environment.
Spitzer_Approved_Extragalactic
Printed_by_SSC
Mar 25, 10 16:24 Page 584/742
Spitzer Space Telescope − General Observer Proposal #20343
IRS Spectroscopy of Cluster Core Filaments
Principal Investigator: Andrew Fabian
Institution: University of Cambridge
Technical Contact: Roderick Johnstone, University of Cambridge
Co−Investigators:
Roderick Johnstone, University of Cambridge
Carolin Crawford, University of Cambridge
Gary Ferland, University of Kentucky
David Alexander, University of Cambridge
Richard Wilman, University of Durham
Nina Hatch, University of Cambridge
Science Category: galaxy clusters and groups
Observing Modes: IrsStare
Hours Approved: 9.7
Abstract:
We propose to make IRS observations, using the high−resolution spectrographs, of
optical emission line filaments in regions ~20 kpc (~1 arcmin) from the nucleus
of NGC 1275, the central galaxy in the Perseus Cluster. These observations will
help us to diagnose the heating mechanism of these filaments, which has been a
long−standing problem, and understand the relation of this gas to the X−ray
emitting intracluster medium. We have detected 2−micron ro−vibrational molecular
hydrodgen lines from these regions with UKIRT. We expect to detect low
excitation members of the H2 0−0 pure rotational line series and will also cover
fine structure lines due to NeII, SI, SIII and Si II. These lines will be
diagnostic of the presence of warm gas (few hundred degrees excitation
temperature) intermediate between the cold CO emitting phase and the much hotter
near infra−red and optically emitting phase. We also propose to cover the
extended emission−line filament to the south of Abell 1795 which shows detailed
correspondence with X−ray emission, and the peculiar dusty H−alpha nebula at the
core of the Centaurus cluster.
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