Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
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Spitzer_Approved_<strong>Extragalactic</strong><br />
Mar 25, 10 16:24 Page 389/742<br />
Spitzer Space Telescope − General Observer Proposal #40459<br />
A mid−infrared study <strong>of</strong> Hickson Compact Groups: Probing the Effects <strong>of</strong><br />
Environment in Galaxy Interactions<br />
Principal Investigator: Emeric Le Floc’h<br />
Institution: <strong>Institute</strong> for Astronomy, University <strong>of</strong> Hawaii<br />
Technical Contact: Emeric Le Floc’h, IfA, U. Hawaii<br />
Co−Investigators:<br />
Vassilis Charmandaris, University <strong>of</strong> Crete<br />
Manolis Xilouris, National Observatory <strong>of</strong> Athens<br />
Martha Haynes, Cornell University<br />
Sara Slater, Harvard University<br />
Science Category: interacting/merging galaxies<br />
Observing Modes: IracMap MipsPhot<br />
Hours Approved: 7.3<br />
Abstract:<br />
It has become increasingly evident that interactions and the merging <strong>of</strong> galaxies<br />
have contributed substantially to their evolution, both in terms <strong>of</strong> their<br />
stellar population and their morphological appearance. Since truly isolated<br />
galaxies are the exception rather than the rule, the immediate environment <strong>of</strong><br />
galaxies has therefore direct implications on their dynamical evolution. Here we<br />
propose to use the unique imaging capabilities <strong>of</strong> Spitzer to study with IRAC and<br />
MIPS a sample <strong>of</strong> 13 Hickson Compact Groups (HCGs) for which we have already<br />
obtained the deepest near−IR images to−date. HCGs are systems <strong>of</strong> 4 or more<br />
galaxies located within a small area on the sky and that exhibit evidence <strong>of</strong><br />
interactions. Reflecting a strong local density enhancement, they occupy a<br />
unique position in the framework <strong>of</strong> galaxy evolution, bridging the range <strong>of</strong><br />
galaxy environments characteristic <strong>of</strong> the field, loose groups and rich clusters.<br />
However, the lack <strong>of</strong> deep high spatial resolution wide field mid−IR imaging <strong>of</strong><br />
those systems has so far left open numerous questions regarding the star forming<br />
properties <strong>of</strong> their member galaxies: are compact groups a transient dynamical<br />
phenomenon? How do they evolve? Is their compact configuration the precursor to<br />
the formation <strong>of</strong> field ellipticals? Are they characterized by warm infrared<br />
colors as the interacting galaxy pairs or is star formation suppressed as in the<br />
center <strong>of</strong> rich clusters? Are they dynamically closed systems or can they<br />
replenish the intergalactic medium with reprocessed material in the form <strong>of</strong> star<br />
forming tails or dwarf galaxies? The Spitzer observations will allow us to<br />
address all these issues and to estimate for the first time the distribution and<br />
the total dust content in these groups. Such data will add in a systematic way a<br />
missing piece to the puzzle <strong>of</strong> how the proximity <strong>of</strong> several interacting galaxies<br />
affects their evolution.<br />
Spitzer_Approved_<strong>Extragalactic</strong><br />
Printed_by_SSC<br />
Mar 25, 10 16:24 Page 390/742<br />
Spitzer Space Telescope − General Observer Proposal #50191<br />
Pushing star formation to the limit: probing the Schmidt−Kennicutt law in<br />
extreme environments<br />
Principal Investigator: Ute Lisenfeld<br />
Institution: Universidad de Granada<br />
Technical Contact: Ute Lisenfeld, Universidad de Granada<br />
Co−Investigators:<br />
Vassilis Charmandaris, University <strong>of</strong> Crete, Greece<br />
Pierre−Alain Duc, Saclay, France<br />
Jonathan Braine, Observatoire de Bordeaux, France<br />
Elias Brinks, University <strong>of</strong> Hertfordshire, England<br />
Kevin, C. Xu, <strong>California</strong> <strong>Institute</strong> <strong>of</strong> <strong>Technology</strong><br />
Mederic Boquien, University <strong>of</strong> Massachusetts, USA<br />
Frederic Bournaud, Saclay, France<br />
Science Category: interacting/merging galaxies<br />
Observing Modes: MipsPhot<br />
Hours Approved: 2.5<br />
Abstract:<br />
We propose to study star formation (SF) in extreme environments in order to test<br />
to breaking point the many prescriptions that have been proposed that predict<br />
under which conditions SF occurs. In particular we will investigate (i) what<br />
sets the threshold for SF and (ii) what determines, once above this threshold,<br />
the rate <strong>of</strong> SF. So far, studies dedicated to this question have been based only<br />
on data <strong>of</strong> spiral and dwarf galaxies. We argue that in order to make progress,<br />
observations are needed <strong>of</strong> SF in extreme environments, such as intergalactic SF<br />
regions. We propose to study the relation between SF and SF rate (SFR), and the<br />
neutral (atomic and molecular) gas in a sample <strong>of</strong> 13 intergalactic SF regions,<br />
spanning a wide range <strong>of</strong> luminosities. All targets have a wealth <strong>of</strong> ancillary<br />
data, mainly obtained by us such as HI, CO, Halpha, and GALEX UV. Although the<br />
latter two are indicators <strong>of</strong> unobscured SF, we know that even in intergalactic<br />
SF regions there is dust and considerable extinction. It is therefore crucial to<br />
obtain MIPS 24 um maps to determine the total SF (obscured and unobscured). A<br />
modest 2.5 hrs total time spent on 13 targets is guaranteed to deliver a<br />
substantial return on investment in the form <strong>of</strong> a much improved understanding <strong>of</strong><br />
the sufficient and necessary conditions for SF to take place.<br />
Thursday March 25, 2010 xgal_covers.txt<br />
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