MCC members hauled in a major amount of JVLA radio observation time in the 2014B semester to study the radio emission of merging clusters. One proposal, led by Will Dawson, will obtain deep (30 total hours) polarization measurements of 5 double radio relic clusters (A1240, MACS J1752.0+4440, RXC J1314.4-2515, ZwCL 0008.8+5215, and ZwCL 2341.1+0000).  These observations will enable us to improve dark matter cross-section constraints by almost an order of magnitude!  The second proposal, led by Reinout van Weeren, will obtain very deep radio observations (64 hours total) of four of the the Frontier Field clusters (MACS J0717, MACS J1149, MACS J0416, and A2744).

MCC member Marcus Bruggen and others have shown how the star formation rate (SFR) in cluster spiral galaxies can be enhanced due to major cluster merger induced shocks of the intra-cluster-medium (Roedigner et al. 2014).  They find that local enhancements in the SFR of about a factor of 4 and global SFR enhancements of a factor of ~1.5, but that these enhancements are limited to a short duration of ~15 Myr following the passage of the shock (typical timescales of cluster mergers are about 1 Gyr). Thus enhanced SFR might be expected to be limited to occurring within galaxies that are a few 100 kpc behind the progressing shock. MCC can test this hypothesis using our extensive Keck galaxy spectra, X-ray & radio observations of the shock, and dynamics analysis.

Reference:
Roediger, E. et al., 2014. Star formation in shocked cluster spirals and their tails. eprint arXiv:1405.1033.

A video by Elke Roediger showing how the projected gas density of a spiral galaxy is affected by a passing intra-cluster-medium shock, common in major cluster mergers. Star formation is more likely in regions with denser gas. See more of Elke's simulation videos at: http://www.hs.uni-hamburg.de/DE/Ins/Per/Roediger/research.html#Spiral.

We are just wrapping up another successful observing run on Subaru, see the previous post for details. Many thanks to the excellent Subaru staff who keep one of the worlds best optical telescopes running smoothly. Particular thanks to our support astronomer Takuya Fujiyoshi and telescope operator Josh Williams.

Despite just taking the observations we are already producing results.  James Jee created the RXC J1314.4-2515 image to the left in a matter of hours.  This is part of our bold plan to image the cluster, reduce the data, create Keck DEIMOS slitmasks, and get the masks milled in time for our Keck observations. All within a 4 day window.  A fun test of our observational expertise. 

This site is a living research space with changes occurring frequently.  Most notably the merging cluster sample summaries are added and updated frequently.  These summaries are a large portion of what will appear in our collaboration's upcoming MCC Radio Relic Sample paper.

While our previous collaboration site (https://sites.google.com/a/ucdavis.edu/merging-cluster-collaboration/) and sample site (www.physics.ucdavis.edu/~dwittman/Table/) served us well, they were disjointed and lacked the functionallity necessary to satisfy our desire to service the broader scientific community.