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Durham University

Department of Physics

Staff profile

Publication details for Prof Richard Massey

Coe, D.A., Dupke, R., Benitez, N., Broadhurst, T., Massey, R., Zitrin, A., Merten, J., Cypriano, E., Braglia, F., Frye, B., Meneghetti, M., Moustakas, L., Rhodes, J., Krick, J., Sodre, L., Bregman, J., Jimenez-Teja, Y. & Bernstein, R. (2011), More Powerful than a Speeding "Bullet"? New HST Images and Analysis of the Galaxy Cluster Merger Abell 2744, Bulletin of the American Astronomical Society 43: 217th American Astronomical Society Meeting. Seattle, Washington, 109.05.

Author(s) from Durham


Abell 2744 is a galaxy cluster merger similar to the Bullet Cluster but more massive and somewhat more complex. A2744 exhibits an even larger (the largest observed) projected separation between dark matter and the stripped, shocked cluster gas ( 54" 240 kpc). We may even be witnessing a triple merger similar to "The Cosmic Train Wreck" (Abell 520) as evidenced in part by Chandra X-ray observations which reveal high temperature shock regions (as high as 15 keV) and a complicated structure. We have obtained new deep (16 orbit), multiband (BVI) HST/ACS images of A2744's core. These images reveal in detail several prominent strong gravitational lensing features due to the SE subcluster, and our lens modeling reveals many more ( 30 total). Here we present these images and new "non-parametric" mass models of A2744 based on simultaneous fitting to strong + weak lensing data in the HST and ground-based images. We discuss the relative positions of the dark matter peaks, galaxies, and gas peaks and implications for limits on the self-interaction cross section of dark matter particles.