ﻻ يوجد ملخص باللغة العربية
We present ALMA measurements of a merger shock using the thermal Sunyaev-Zeldovich (SZ) effect signal, at the location of a radio relic in the famous El Gordo galaxy cluster at $z approx 0.9$. Multi-wavelength analysis in combination with the archival Chandra data and a high-resolution radio image provides a consistent picture of the thermal and non-thermal signal variation across the shock front and helps to put robust constraints on the shock Mach number as well as the relic magnetic field. We employ a Bayesian analysis technique for modeling the SZ and X-ray data self-consistently, illustrating respective parameter degeneracies. Combined results indicate a shock with Mach number ${cal M} = 2.4^{+1.3}_{-0.6}$, which in turn suggests a high value of the magnetic field (of the order of $4-10 ~mu$G) to account for the observed relic width at 2 GHz. At roughly half the current age of the universe, this is the highest-redshift direct detection of a cluster shock to date, and one of the first instances of an ALMA-SZ observation in a galaxy cluster. It shows the tremendous potential for future ALMA-SZ observations to detect merger shocks and other cluster substructures out to the highest redshifts.
The thermal Sunyaev-Zeldovich (SZ) effect presents a relatively new tool for characterizing galaxy cluster merger shocks, traditionally studied through X-ray observations. Widely regarded as the textbook example of a cluster merger bow shock, the wes
We present the on-going activity to characterize the geometrical properties of the gas and dark matter haloes using multi-wavelength observations of galaxy clusters. The role of the SZ signal in describing the gas distribution is discussed for the pi
We present a weak-lensing analysis of the z=1.4 galaxy cluster XMMU J2235.3-2557, based on deep Advanced Camera for Surveys images. Despite the observational challenge set by the high redshift of the lens, we detect a substantial lensing signal at th
The Sunyaev-Zeldovich (SZ) effect was first predicted nearly five decades ago, but has only recently become a mature tool for performing high resolution studies of the warm and hot ionized gas in and between galaxies, groups, and clusters. Galaxy gro
We present results from a 577 ks XMM-Newton observation of SPT-CL J0459-4947, the most distant cluster detected in the South Pole Telescope 2500 square degree (SPT-SZ) survey, and currently the most distant cluster discovered through its Sunyaev-Zeld