MCC Radio Relic SampleThe predicted galaxy-DM offset is a function of cluster surface mass density, collision speed, and time since pericenter as well as the DM particle model. Thus, an ensemble of systems spanning a range of dynamical properties provides great leverage for confirming or ruling out an SIDM-based explanation for any detected offsets (and perhaps eventually discriminating between SIDM models). However, one constant is the need for systems as close to transverse as possible so that any galaxy-DM offset can actually be observed. Therefore, we are pursuing a sample of systems with radio relics, which are the radio signatures of transversely-viewed shock fronts: very extended in one direction but narrow in the orthogonal direction (see e.g. van Weeren et al. 2010). This should select for transverse systems and also helps define the azimuth of the merger axis, particularly when a counter-relic is also observed. The projection angle can be further constrained using the radio relic polarization. The relic also fades with time, so relic selection helps select systems which are young enough to retain a galaxy-DM offset. We have selected the 26 "elongated" radio relic clusters from the Feretti et al. (2012) review that have z ≥ 0.09.
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MCC Chandra-Planck Merging Cluster SampleThe Chandra-Planck Legacy Program for Massive Clusters of Galaxies is a deep X-ray survey of all 165 Planck detected clusters below a redshift of 0.35 (and |b| > 15 deg). The survey depth (at least 10,000 X-ray photons per cluster) coupled with Chandra’s high resolution enables accurate characterization of each cluster’s dynamical state based on gas morphology, temperature, and density. The Merging Cluster Collaboration (MC2) is partnering with the Chandra-Planck team to perform a Subaru (Hyper)SuprimeCam weak lensing and Keck DEIMOS spectroscopic survey of the northern 30 most massive X-ray identified mergers. This sample covers a much wider range of merger phase space than the MC2 Radio Relic Sample (which selects for older systems) and will provide the necessary leverage to address a number of outstanding questions as well as explore new frontiers in plasma/particle physics, galaxy evolution, and self-interacting dark matter (SIDM).
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Other Proven Dissociative Mergers
| Name | RA | Dec | z | Nspec | AV | Radio | Comments |
|---|---|---|---|---|---|---|---|
| 1E0657-56 (Bullet) | 06h58m29.2s | -55d57m10s | 0.296 | 13 | 0.213 | UL | Markevitch et al 2004 |
| Abell 1758 | 13h32m32.1s | +50d30m37s | 0.279 | 10 | 0.029 | DR | Boschin et al 2012 |
| Abell 520 | 04h54m19.0s | +02d56m49s | 0.199 | 206 | 0.148 | H | Jee et al 2012 |
| Abell S1063 | 22h48m54.3s | -44d31m07s | 0.347 | 51 | 0.034 | R | Gomez et al 2012 |
| ACT-CL J0102-4915 (Gordo) | 01h02m00.0s | -49d15m00s | 0.75 | 200? | 0.032 | DR | Menanteau et al 2012 |
| DLS-CL J0916.2+2951 (Musket Ball) | 09h16m12s | +29d51m | 0.53 | 600 | 0.066 | UL | Dawson et al 2012 |
| MACS J0025.4-1222 (Baby Bullet) | 00h25m30s | -12d22m45s | 0.58 | 5 (108) | 0.098 | ND | Bradac et al 2008 |
Other Merging Clusters
This is a very incomplete list of other merging clusters that are not classed as dissociative. They may be premergers or mergers
| Name | RA | Dec | z | Nspec | AV | Radio | Comments |
|---|---|---|---|---|---|---|---|
| A1656 (Coma) | 12h58m50s | +27d58m50s | 0.023 | 373 | ? | Y | relic (G09) |
| A1758 | 13h32m32.1s | +50d30m37s | 0.279 | 10 | ? | Y | relic (G09) |
| A209 | 01h31m53.0s | -13d36m42s | 0.206 | 136 | ? | Y | relic (G09) |
| CygnusA | 19h59m28.3s | +40d44m02s | 0.056 | 102 | ? | Y | |
| Abell 2146 | ? | Russell et al. (2010-2012) |