Image of Alice in Wonderland at the Mad Hatter's tea party You are cordially invited to afternoon tea and biscuits wine and chocolate

Astronomy Tea Talks at Caltech

Mondays, Hameetman auditorium (Cahill)
Tea:  4.00pm
Talk: 4.15pm

Organized by:

2011 - 2012 season:
12 March 2012 Matt George (Berkeley)

Galaxies in X-ray Groups: Finding Halo Centers and Tracking Evolution

Groups and clusters are important sites of galaxy evolution as well as interesting laboratories to study the interplay of galaxies, hot gas, and dark matter halos. A key challenge is to disentangle the roles that stellar mass and environmental processes play in shaping galaxy properties over time. To address this problem within a well-defined environment, we have constructed a sample of 129 galaxy groups in the COSMOS field. The groups are X-ray selected over the redshift range z=0-1 and have halo masses determined from stacked weak lensing. In this talk I will present results from two analyses of this group catalog. First, by measuring the lensing signal stacked around different candidate group centers (e.g. X-ray peak, brightest galaxy, centroid of member positions), we determine which observational tracer best identifies the center of mass of the halo. Second, we show how transformations in a galaxy's properties depend on its position within a group, and that changes in color and morphology take place over different timescales. I will also briefly discuss how a census of star-forming galaxies in these groups can aid in the interpretation of recent SZ measurements.
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Last modified on 08th Mar 2012 by Marco Viero.  

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