Revealing the ICM transport properties with a deep Chandra observation of Abell 2146 Helen Russell Jeremy Sanders Andy Fabian Brian McNamara Reinout van Weeren Alastair Edge Chris O'Dea Megan Donahue Stefi Baum Becky Canning Lindsay King Sakurako Okamoto Outline Intro to galaxy cluster merger shock fronts ● Abell 2146: two merger shock fronts 400ks Chandra observation ● Establishment of electron-ion equilibrium ➔ GMRT 325MHz radio observation ● Lack of extended radio emission ➔ Conclusions ● Galaxy cluster mergers Evidence for dark matter ● Constraints on DM self-interaction cross section ● Intracluster medium transport processes ● Electron-ion equilibrium, viscosity, conduction, ● turbulence Radio halos, relics + ● relativistic particle acceleration Bullet cluster, Markevitch 2006, Clowe et al. 2006 Detection of shock fronts Subcluster velocity in the plane of the sky ● Merger geometry, timescale + evolution ● Bullet cluster, Markevitch 2006, Abell 520, Markevitch et al. 2005, Clowe et al. 2006 Mahdavi et al. 2007 Abell 2146: 400 ks Chandra L = 1.6 x 1045 erg/s ● X T = 6.7 keV ● X redshift 0.23 ● Abell 2146 Optical R-band Subaru image: S. Okamoto, L. King Deep Chandra observation X-ray surface brightness Unsharp masked image Bow shock Bow shock: ρ /ρ = 2.4 ± 0.2 1 2 Bow shock Bow shock: ρ /ρ = 2.4 ± 0.2 1 2 M = 2.1 ± 0.2 Electron-ion equilibration: Bullet Markevitch 2006