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 609/742<br />
Spitzer Space Telescope − General Observer Proposal #30507<br />
Far−infrared Emission from the Coma Cluster <strong>of</strong> Galaxies<br />
Principal Investigator: Tetsu Kitayama<br />
Institution: Toho University<br />
Technical Contact: Tetsu Kitayama, Toho University<br />
Co−Investigators:<br />
Hidehiro Kaneda, <strong>Institute</strong> <strong>of</strong> Space and Astronautical Science<br />
Hidenori Takahashi, The University <strong>of</strong> Tokyo<br />
Yuka Yoshikawa Tajiri, The University <strong>of</strong> Tokyo<br />
Takashi Onaka, The University <strong>of</strong> Tokyo<br />
Itsuki Sakon, The University <strong>of</strong> Tokyo<br />
Naomi Ota, RIKEN<br />
Hirohisa Nagata, National Astronomical Observatory <strong>of</strong> Japan<br />
Kenkichi Yamada, Toho University<br />
Science Category: galaxy clusters and groups<br />
Observing Modes: MipsScan<br />
Hours Approved: 11.4<br />
Abstract:<br />
We propose MIPS observations <strong>of</strong> the Coma cluster <strong>of</strong> galaxies (A1656), aiming at<br />
the first firm detection <strong>of</strong> intergalactic dust grains. Clusters <strong>of</strong> galaxies<br />
provide a unique environment <strong>of</strong> dust−gas interactions; the X−ray emitting plasma<br />
can heat the dust to 10−20 K via collisions, as well as destroy small grains via<br />
sputtering. Recent claim <strong>of</strong> detecting collisionally heated dust grains in Coma<br />
by ISOPHOT (Stickel et al. 2002), however, has been much debated owing to<br />
insufficient quality <strong>of</strong> the data. With MIPS, we can test their result<br />
unambiguously for the first time. In addition, multi−wavelength detections<br />
enable us to determine both the amount and the mean temperature <strong>of</strong> the grains.<br />
Combined with X−ray and optical data, they further provide powerful clues to<br />
understanding the dust−gas interaction and the ejection history <strong>of</strong> dust from<br />
galaxies. In case <strong>of</strong> no detection, we are still able to place severe constraints<br />
on its amount, which is a meaningful step forward in the long−standing argument<br />
regarding the intergalactic dust. Our observation will therefore provide a<br />
unique opportunity <strong>of</strong> probing the nature <strong>of</strong> dust grains in relation to the<br />
ambient hot gas and host galaxies.<br />
Spitzer_Approved_<strong>Extragalactic</strong><br />
Printed_by_SSC<br />
Mar 25, 10 16:24 Page 610/742<br />
Spitzer Space Telescope − General Observer Proposal #40652<br />
Galaxy Evolution in the Cluster/Filament Environment<br />
Principal Investigator: Dale Kocevski<br />
Institution: University <strong>of</strong> <strong>California</strong>, Davis<br />
Technical Contact: Dale Kocevski, University <strong>of</strong> <strong>California</strong>, Davis<br />
Co−Investigators:<br />
Harald Ebeling, University <strong>of</strong> Hawaii<br />
Cheng−Jiun Ma, University <strong>of</strong> Hawaii<br />
Science Category: galaxy clusters and groups(high−z)<br />
Observing Modes: IracMap MipsScan<br />
Hours Approved: 16.0<br />
Abstract:<br />
Recent studies have found that the outskirts <strong>of</strong> galaxy clusters, such as the<br />
filament networks which feed them, play a pivotal role in driving galaxy<br />
evolution well before galaxies reach the cluster environment. Several processes<br />
have been proposed that would transform galaxies in the low−density regime, some<br />
<strong>of</strong> which directly suppress star formation activity and others that would instead<br />
trigger a burst <strong>of</strong> star formation that consumes most <strong>of</strong> the galaxy’s gas supply.<br />
We can directly test for this latter class <strong>of</strong> mechanisms by searching for a<br />
starbursting population <strong>of</strong> galaxies in and around clusters. Furthermore since<br />
many <strong>of</strong> the proposed processes are most effective at different galaxy and gas<br />
densities, the properties <strong>of</strong> the local environment in which starburst galaxies<br />
are found can help constrain the mechanisms which trigger them. We propose 3.6−8<br />
micron IRAC and 24 micron MIPS observations <strong>of</strong> a well defined and highly studied<br />
large−scale filament feeding the massive cluster MACS J0717.5+3745 at z=0.55.<br />
The filament is a highly coherent, spectroscopically confirmed structure<br />
detected in our galaxy surface density maps, weak lensing analysis and X−ray<br />
observations. We have compiled an extensive multi−wavelength dataset to aid in<br />
this study, including an 18−pointing, high−resolution HST ACS mosaic <strong>of</strong> the<br />
field. The environment around MACS J0717.5+3745 is well suited to investigate<br />
the mechanisms which trigger starburst activity and drive galaxy evolution in<br />
clusters as it provides a full range <strong>of</strong> environments to probe, from the cluster<br />
core to the filament−cluster interface and out to the low density regime <strong>of</strong> the<br />
filament proper. By examining the properties <strong>of</strong> the local environment in which<br />
starburst galaxies are activated, along with their morphological and<br />
spectroscopic attributes we can place strong constraints on the physical<br />
processes which trigger such activity and ultimately transform field galaxies<br />
into the passively evolving population <strong>of</strong> galaxies predominately found in<br />
clusters.<br />
Thursday March 25, 2010 xgal_covers.txt<br />
305/371