The Atacama Cosmology Telescope: ACT-CL J0102-4915 "El Gordo," a Massive Merging Cluster at Redshift 0.87
Felipe Menanteau, John P. Hughes, Cristobal Sifon, Matt Hilton, Jorge Gonzalez, Leopoldo Infante, L. Felipe Barrientos, Andrew J. Baker, John R. Bond, Sudeep Da… 展开作者
Felipe Menanteau, John P. Hughes, Cristobal Sifon, Matt Hilton, Jorge Gonzalez, Leopoldo Infante, L. Felipe Barrientos, Andrew J. Baker, John R. Bond, Sudeep Das, Mark J. Devlin, Joanna Dunkley, Amir Hajian, Adam D. Hincks, Arthur Kosowsky, Danica Marsden, Tobias A. Marriage, Kavilan Moodley, Michael D. Niemack, Michael R. Nolta, Lyman A. Page, Erik D. Reese, Neelima Sehgal, Jon Sievers, David N. Spergel, Suzanne T. Staggs, Edward Wollack
备注：
Typo on metadata fixed on version 3. Accepted for publication in The Astrophysical Journal; 17 pages, 15 figures. New section 4.4 includes radio relic science
We present a detailed analysis from new multi-wavelength observations of the exceptional galaxy cluster ACT-CL J0102-4915 "El Gordo," likely the most massive, hottest, most X-ray luminous and brightest Sunyaev-Zeldovich (SZ) effect cluster known at z>0.6. The Atacama Cosmology Telescope collaboration discovered El Gordo as the most significant SZ decrement in a sky survey area of 755 deg^2. Our VLT/FORS2 spectra of 89 member galaxies yield a cluster redshift, z=0.870, and velocity dispersion, s=1321+/-106 km/s. Our Chandra observations reveal a hot and X-ray luminous system with an integrated temperature of Tx=14.5+/-1.0 keV and 0.5-2.0 keV band luminosity of Lx=(2.19+/-0.11)x10^45 h70^-2 erg/s. We obtain several statistically consistent cluster mass estimates; using mass scaling relations with velocity dispersion, X-ray Yx, and integrated SZ, we estimate a cluster mass of M200a=(2.16+/-0.32)x10^15 M_sun/h70. The Chandra and VLT/FORS2 optical data also reveal that El Gordo is undergoing a major merger between components with a mass ratio of approximately 2 to 1. The X-ray data show significant temperature variations from a low of 6.6+/-0.7 keV at the merging low-entropy, high-metallicity, cool core to a high of 22+/-6 keV. We also see a wake in the X-ray surface brightness caused by the passage of one cluster through the other. Archival radio data at 843 MHz reveal diffuse radio emission that, if associated with the cluster, indicates the presence of an intense double radio relic, hosted by the highest redshift cluster yet. El Gordo is possibly a high-redshift analog of the famous Bullet Cluster. Such a massive cluster at this redshift is rare, although consistent with the standard L-CDM cosmology in the lower part of its allowed mass range. Massive, high-redshift mergers like El Gordo are unlikely to be reproduced in the current generation of numerical N-body cosmological simulations.
A massive blow for $Λ$CDM $-$ the high redshift, mass, and collision velocity of the interacting galaxy cluster El Gordo contradicts concordance cosmology
Probing High-redshift Intracluster Medium Using SKA
National Centre for Radio Astrophysics, Tata Institute of Fundamental Research（国家射电天体物理学中心，塔塔基础研究所）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（国际理论科学中心，塔塔基础研究所）
