Mass and gas profiles in A1689: Joint X-ray and lensing analysis

Doron Lemze*, Rennan Barkana, Tom J. Broadhurst, Yoel Rephaeli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We carry out a comprehensive joint analysis of high-quality HST/ACS and Chandra measurements of A1689, from which we derive mass, temperature, X-ray emission and abundance profiles. The X-ray emission is smooth and symmetric, and the lensing mass is centrally concentrated indicating a relaxed cluster. Assuming hydrostatic equilibrium we deduce a 3D mass profile that agrees simultaneously with both the lensing and X-ray measurements. However, the projected temperature profile predicted with this 3D mass profile exceeds the observed temperature by ∼30 per cent at all radii, a level of discrepancy comparable to the level found for other relaxed clusters. This result may support recent suggestions from hydrodynamical simulations that denser, more X-ray luminous small-scale structure can bias observed temperature measurements downward at about the same (∼30 per cent) level. We determine the gas entropy at 0.1rvir (where rvir is the virial radius) to be ∼800 keV cm2, as expected for a high-temperature cluster, but its profile at >0.1rvir has a power-law form with index ∼0.8, considerably shallower than the ∼1.1 index advocated by theoretical studies and simulations. Moreover, if a constant entropy 'floor' exists at all, then it is within a small region in the inner core, r < 0.02rvir, in accord with previous theoretical studies of massive clusters.

Original languageEnglish
Pages (from-to)1092-1106
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - May 2008


  • Galaxies: clusters: individual: A1689


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