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. 

We are conducting another Subaru SuprimeCam and Keck DEIMOS observing run.  Both telescopes are located on summit of Mauna Kea (~4,200 meters) on the Big Island of Hawaii. A site that provides some of the best observing conditions on the planet.

We will observe 15 radio relic cluster mergers over two nights (24-25 Feb. 2014) with the Subaru SuprimeCam. The primary objective of this observing run will be to obtain high quality imaging in multiple bands (griz) in order to map the cluster galaxies and dark matter (via gravitational lensing). 

Following the Subaru run we will observe 5 radio relic cluster mergers with Keck DEIMOS (1 Mar. 2014).  These observations will provide ~1,500 new spectra of galaxies within these merging systems. The spectra will provide important information about the velocities of these galaxies, which in turn provides information about the collision velocity of the merger.  Additionally these spectra will provide information about how the galaxies in these mergers are evolving and whether their evolution has been influenced by the major cluster mergers.

Subaru Targets:
- PLCK G287.0+32.9
- MACS J1752.0+2223
- Abell 3411
- Abell 3365
- Abell 2061
- Abell 2034
- Abell 1612
- Abell 1300
- Abell 1240
- Abell 746
- Abell 523
- 1RXS J0603.2+4212
- RXC J1053.7+5452
- RXC J1314.4-2515
- ZwCL 1447.2+2619

Keck Targets:
- Abell 523- Abell 1612
- MACS J1149.5+2223
- PLCK G287.0+32.9
- RXC J1314.4-2515

We just opened up our new site MergingClusterCollaboration.org.  The primary objectives of the new site are to:

1. Provide an overview of our science
2. Highlight our collaboration members
3. Provide summaries of known radio relic and dissociative mergers. Including literature reviews, existing data, and basic properties (for example).
4. Provide a portal to the MCC public data. Including, imaging and spectroscopic catalogs.

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.