Open AccessEntropy of the intracluster medium at high redshift
Author(s) -
Nath Biman B.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08124.x
Subject(s) - physics , redshift , intracluster medium , astrophysics , scaling , entropy (arrow of time) , galaxy cluster , astronomy , galaxy , geometry , quantum mechanics , mathematics
Recent observations of the entropy of the intracluster medium (ICM) at high redshift are not consistent with a redshift‐independent entropy floor. To interpret these observations, we study models in which the entropy of ICM is enhanced at the epoch of cluster formation ( z f ), which then passively evolves as a result of radiative cooling until the epoch of observation ( z o ). We confirm that a z ‐independent entropy floor is incompatible with the observations. We find that models in which energy deposition into the ICM increases with redshift [scaling approximately as ∼ M 0.6 cl (1 + z f ) 2.2 ] are consistent with observations of low‐ and high‐redshift clusters. Possible sources of such non‐gravitational heating are briefly discussed.