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The Atacama Cosmology Telescope : ACT-CL J0102-4215 "El Gordo," a Massive Merging Cluster at Redshift 0.87.

Author:
Gonzalez, Jorge
Published:
September 04, 2011.
Physical Description:
1 electronic document
Additional Creators:
Barrientos, L. Felipe, Sehgal, Neelima, Page, Lyman A., Infante, Leopoldo, Sievers, Jon, Spergel, David N., Sifon, Cristobal, Niemack, Michael D., Staggs, Suzanne T., Marriage, Tobias A., Kosowsky, Arthur, Hincks, Adam D., Hilton, Matt, Menanteau, Felipe, Dunkley, Joanna, Mardsen, Danica, Das, Sudeep, Baker, Andrew J., Moodley, Kavilan, Reese, Erik D., and Hughes, John Pl
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Summary:
We present a detailed analysis from new multi-wavelength observations of the exceptional galaxy cluster ACT-CL J0102-4915, likely the most massive, hottest, most X-ray luminous and brightest Sunyaev-Zel'dovich (SZ) effect cluster known at redshifts greater than 0.6. The Atacama Cosmology Telescope (ACT) collaboration discovered ACT-CL J0102-4915 as the most significant Sunyaev-Zeldovich (SZ) decrement in a sky survey area of 755 square degrees. Our VLT/FORS2 spectra of 89 member galaxies yield a cluster redshift, z = 0.870, and velocity dispersion, sigma(gal) +/- 1321 106 km s-1. Our Chandra observations reveal a hot and X-ray luminous system with an integrated temperature of T(X) = 14:5 +/- 0:1 keV and 0.5 2.0 keV band luminosity of L(X) = (2:19 0:11) 1045 h(exp -2)70erg s-1. We obtain several statistically consistent cluster mass estimates; using empirical mass scaling relations with velocity dispersion, X-ray Y(X) , and integrated SZ distortion, we estimate a cluster mass of M(200) = (2:16 +/- 0:32) 10(exp 15) h(exp-1) 70M compared to the Sun. We constrain the stellar content of the cluster to be less than 1% of the total mass, using Spitzer IRAC and optical imaging. The Chandra and VLT/FORS2 optical data also reveal that ACT-CL J0102-4915 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 and deprojected gas density caused by the passage of one cluster through the other from which we estimate a merger speed of around 1300 km s(exp -1) for an assumed merger timescale of 1 Gyr. ACTCL J0102-4915 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 CDM cosmology in the lower part of its allowed mass range. Massive, high-redshift mergers like ACT-CL J0102-4915 are unlikely to be reproduced in the current generation of numerical N-body cosmological simulations.
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Collection:
NASA Technical Reports Server (NTRS) Collection.
Note:
Document ID: 20120002647.
GSFC.JA.5672.2011.
Terms of Use and Reproduction:
Copyright, Distribution as joint owner in the copyright.
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