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Extragalactic abstracts - IRSA - California Institute of Technology

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Spitzer_Approved_<strong>Extragalactic</strong><br />

Mar 25, 10 16:24 Page 719/742<br />

Spitzer Space Telescope − General Observer Proposal #20542<br />

Selecting dusty starburst galaxies at z=1.5 using a silicate absorption feature<br />

Principal Investigator: Colin Borys<br />

Institution: Caltech<br />

Technical Contact: Duncan Farrah, Cornell University<br />

Co−Investigators:<br />

Duncan Farrah, Infrared Processing and Analysis Center<br />

Philip Choi, Spitzer Science Center<br />

Dave Frayer, Spitzer Science Center<br />

Science Category: starburst galaxies<br />

Observing Modes: IrsStare<br />

Hours Approved: 18.4<br />

Abstract:<br />

We propose Spitzer IRS spectroscopy <strong>of</strong> a sample <strong>of</strong> 15 high redshift dusty<br />

starburst galaxies. The sample, drawn from the SWIRE and FLS surveys, is based<br />

on a silicate absorption feature at 9.7 microns being redshifted into the MIPS<br />

24 micron band. Thus, the objects should all be around a redshift <strong>of</strong> z=1.5.<br />

This is a traditionally difficult epoch to obtain optical spectra <strong>of</strong> galaxies,<br />

and is known as the "redshift desert". Our proposed observations will validate<br />

the selection technique and, if successful, allow us to draw samples <strong>of</strong> hundreds<br />

<strong>of</strong> z=1.5 dusty starburst galaxies contained in the rich spitzer Legacy data<br />

sets.<br />

Spitzer_Approved_<strong>Extragalactic</strong><br />

Printed_by_SSC<br />

Mar 25, 10 16:24 Page 720/742<br />

Spitzer Space Telescope − General Observer Proposal #20767<br />

Mid−IR spectroscopy <strong>of</strong> suspected very hot dusty, high−z galaxies<br />

Principal Investigator: Scott Chapman<br />

Institution: Caltech<br />

Technical Contact: Scott Chapman, Caltech<br />

Co−Investigators:<br />

Andrew Blain, Caltech<br />

Ian Smail, U.Durham<br />

Rob Ivison, U.Edinburgh<br />

Science Category: starburst galaxies<br />

Observing Modes: IrsStare<br />

Hours Approved: 23.7<br />

Abstract:<br />

We have identified a population <strong>of</strong> high−redshift microJy radio sources which<br />

have optical and near−IR photometric and spectroscopic properties characteristic<br />

<strong>of</strong> dusty luminous starbursts, and whose radio emission is as intense as expected<br />

from this class <strong>of</strong> galaxy, but which have no detectable submm emission from cool<br />

dust. As these galaxies are detected with ~0.5mJy 24micron fluxes, we propose<br />

that they are a new class <strong>of</strong> luminous dusty starbursts with characteristic dust<br />

temperatures that are hotter than the similarly high−redshift ultraluminous<br />

submillimeter−selected galaxies (SMGs) identified in deep submm surveys. The<br />

radio emission from these submm−faint radio galaxies indicates far−IR<br />

luminosities that are comparable to those <strong>of</strong> the SMGs. We propose Spitzer IRS<br />

observations <strong>of</strong> 6 <strong>of</strong> these galaxies to to probe the intense mid−IR emission from<br />

these galaxies for signatures <strong>of</strong> their power source. We expect that large<br />

numbers <strong>of</strong> these galaxies will be detected in mid−IR Spitzer surveys, and we can<br />

rapidly and efficiently define their observational characteristics by exploiting<br />

our existing radio−selected spectroscopic sample.<br />

Thursday March 25, 2010 xgal_covers.txt<br />

360/371

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