科研之友
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摘要
We present a new analysis of very deep Chandra observations of the galaxy cluster A1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to resolve the thermodynamic structure of the intracluster medium (ICM) on length scales of similar to 1 kpc near the cool core. We find several previously unresolved structures, including a high pressure feature to the north of the Brightest Cluster Galaxy (BCG) that appears to arise from the bulk motion of A1795's cool core. To the south of the cool core, we find low temperature (similar to 3 keV), diffuse ICM gas extending for distances of similar to 50 kpc spatially coincident with previously identified filaments of Ha emission. Gas at similar temperatures is also detected in adjacent regions without any Ha emission. The X-ray gas coincident with the Ha filament has been measured to be cooling spectroscopically at a rate of similar to 1M(circle dot)yr(-1), consistent with measurements of the star formation rate in this region as inferred from ultraviolet (UV) observations, suggesting that the star formation in this filament as inferred by its Ha and UV emission can trace its origin to the rapid cooling of dense, X-ray emitting gas. The H alpha filament is not a unique site of cooler ICM, however, as ICM at similar temperatures and even higher metallicities not cospatial with Ha emission is observed just to the west of the Ha filament, suggesting that it may have been uplifted by A1795's central active galaxy. Further simulations of cool core sloshing and active galactic nucleus feedback operating in concert with one another will be necessary to understand how such a dynamic cool core region may have originated and why the Ha emission is so localized with respect to the cool X-ray gas.
- 出版日期2015-2-1
- 单位MIT
