Extragalactic abstracts - IRSA - California Institute of Technology

Spitzer_Approved_Extragalactic
Mar 25, 10 16:24 Page 339/742
Spitzer Space Telescope − General Observer Proposal #50189
A Close Look at z>5 Galaxy Analogues in the Local Universe
Principal Investigator: Elizabeth Stanway
Institution: University of Bristol
Technical Contact: Elizabeth Stanway, University of Bristol
Co−Investigators:
Luke Davies, University of Bristol
Matthew Lehnert, GEPI, Observatoire de Paris, France
Laura Douglas, Gepi, Observatoire de Paris, France
Malcolm Bremer, University of Bristol
Science Category: high−z galaxies (z>0.5)
Observing Modes: IracMap IrsStare
Hours Approved: 16.5
Abstract:
Lyman break galaxies (LBGs) at high redshifts (z>5) probe the earliest stages of
massive galaxy formation, exploring a low−metallicity/low−mass regime seldom
seen in today’s universe. In order to overcome the difficulty of studying the
most distant objects, we have identified a rare set of local galaxies with
rest−frame ultraviolet−optical properties similar to those of z>5 LBGs from the
joint GALEX−SDSS databases. We propose to extend our study of these galaxies
into the infrared, studying their stellar, dust and gas content, and for the
first time obtaining a true estimate of the specific star formation density in
this mode of star formation. In particular, these observations should help
answer several key unknowns about the highest redshift LBGs. With IRS
spectroscopy we will determine whether the molecular gas is too heated to
continue star formation for an extended period, explaining the short−lived and
stochastic star formations seen at z=5. Photoionization analysis of ratios of
high ionization potential forbidden lines available in combination with the
strong, narrow optical emission lines will determine the hardness of the
ionising spectrum. Finally, a full UV−Far−IR SED employing data from GALEX,
SDSS, IRAC and MIPS will allow us to relate these intense starbursts to other
known starbursts, in particular the amount of dust emission per unit mass and
quantity of obscured star formation in these systems.
Spitzer_Approved_Extragalactic
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Spitzer Space Telescope − General Observer Proposal #20190
Bolometric Star Formation Rates as a Function of Large−Scale Environment at Z~2
Principal Investigator: Charles Steidel
Institution: California Institute of Technology
Technical Contact: Charles Steidel, California Institute of Technology
Co−Investigators:
Naveen Reddy, California Institute of Technology
Alice Shapley, University of California at Berkeley
Dawn Erb, California Institute of Technology
Max Pettini, Institute of Astronomy, University of Cambridge
Kurt Adelberger, Carnegie Institution of Washington
Jiasheng Huang, Harvard−Smithsonian Center for Astrophysics
Pauline Barmby, Harvard−Smithsonian Center for Astrophysics
Science Category: high−z galaxies (z>0.5)
Observing Modes: MipsPhot
Hours Approved: 22.8
Abstract:
We propose Spitzer/MIPS 24 micron observations in the HS1700+643 field to study
the bolometric energy production from galaxies within and surrounding the most
significant cluster−scale over−density at z>1.5, at a time when massive galaxies
were forming most of their stars. This over−density is at z=2.300, placing the
strong 7.7 micron feature observed in star−forming galaxies in the MIPS 24
micron filter, and therefore makes MIPS observations ideally suited for studying
the star formation rates and energetics of galaxies as a function of
environment. Stellar population modeling of broad−band UV to Spitzer/IRAC SEDs
indicates significant differences in the ages and masses of galaxies within and
outside of the proto−cluster. The proposed MIPS observations will allow us to
determine if these differences extend to the bolometric energy output of
galaxies in the proto−cluster and surrounding environment in a manner that is
completely independent of the degeneracies of SED modeling and uncertainties in
extinction. The extensive multi−wavelength data in the field containing the
proto−cluster will allow for the unprecedented opportunity to compare
MIPS−inferred bolometric SFRs with UV and Halpha estimates on a galaxy−by−galaxy
basis to establish star formation relations for galaxies with a wide range in
ages, stellar masses, and luminosities at z~2. Spitzer/MIPS observations of the
HS1700+643 proto−cluster therefore offer the opportunity to understand
star−formation and its environmental dependencies in a unique and well−studied
laboratory at high redshift.
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