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Chandra observation of two shock fronts in the merging galaxy cluster Abell 2146

Russell, H.R.; Sanders, J.S.; Fabian, A.C.; Baum, S.A.; Donahue, M.; Edge, A.C.; McNamara, B.R.; O'Dea, C.P.


H.R. Russell

J.S. Sanders

A.C. Fabian

S.A. Baum

M. Donahue

B.R. McNamara

C.P. O'Dea


We present a new Chandra observation of the galaxy cluster Abell 2146 which has revealed a complex merging system with a gas structure that is remarkably similar to the Bullet cluster. The X-ray image and temperature map show a cool 2 –3 keV subcluster with a ram pressure stripped tail of gas just exiting the disrupted 6 − 7 keV primary cluster. From the sharp jump in the temperature and density of the gas, we determine that the subcluster is preceded by a bow shock with a Mach number M= 2.2 ± 0.8, corresponding to a velocity v= 2200+1000−900 km s−1 relative to the main cluster. We estimate that the subcluster passed through the primary core only 0.1 –0.3 Gyr ago. In addition, we observe a slower upstream shock propagating through the outer region of the primary cluster and calculate a Mach number M= 1.7 ± 0.3. Based on the measured shock Mach numbers M∼ 2 and the strength of the upstream shock, we argue that the mass ratio between the two merging clusters is between 3 and 4 to one. By comparing the Chandra observation with an archival Hubble Space Telescope observation, we find that a group of galaxies is located in front of the X-ray subcluster core but the brightest cluster galaxy is located immediately behind the X-ray peak.


Russell, H., Sanders, J., Fabian, A., Baum, S., Donahue, M., Edge, A., …O'Dea, C. (2010). Chandra observation of two shock fronts in the merging galaxy cluster Abell 2146. Monthly Notices of the Royal Astronomical Society, 406(3), 1721-1733.

Journal Article Type Article
Publication Date Aug 1, 2010
Deposit Date Jan 30, 2012
Publicly Available Date Aug 21, 2013
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 406
Issue 3
Pages 1721-1733
Keywords Galaxies, Clusters, Abell 2146, Intergalactic medium, X-rays.


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