COSMOLOGICAL EFFECTS OF POWERFUL AGN OUTBURSTS IN GALAXY CLUSTERS: INSIGHTS FROM AN XMM-NEWTON OBSERVATION OF MS 0735+7421

摘要

We report on the results of an analysis of XMM-Newton observations of MS 0735+7421, the galaxy cluster that hosts the most energetic AGN outburst currently known. The previous Chandra image shows twin giant X-ray cavities (～200 kpc diameter) filled with radio emission and surrounded by a weak shock front. XMM data are consistent with these findings. The total energy in cavities and shock (～6 x 10~(61) ergs) is enough to quench the cooling flow and, since most of the energy is deposited outside the cooling region (～100 kpc), to heat the gas within 1 Mpc by ～1/4 keV per particle. The cluster exhibits an upward departure (factor ～2) from the mean L-T relation. The boost in emissivity produced by the ICM compression in the bright shells due to the cavity expansion may contribute to explain the high luminosity and high central gas mass fraction that we measure. The scaled temperature and metallicity profiles are in general agreement with those observed in relaxed clusters. Also, the quantities we measure are consistent with the observed M-T relation. We conclude that violent outbursts such as the one in MS 0735+7421 do not cause dramatic instantaneous departures from cluster scaling relations (other than the L-T relation). However, if they are relatively common they may play a role in creating the global cluster properties.