The rich globular cluster system of Abell 1689 and the radial dependence of the globular cluster formation efficiency

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DOIResolve DOI: http://doi.org/10.1088/0004-637X/775/1/20
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TypeArticle
Journal titleThe Astrophysical Journal
ISSN0004-637X
Volume775
Issue1
Article number20
AbstractWe study the rich globular cluster (GC) system in the center of the massive cluster of galaxies Abell 1689 (z = 0.18), one of the most powerful gravitational lenses known. With 28 Hubble Space Telescope/Advanced Camera for Surveys orbits in the F814W bandpass, we reach a magnitude I 814 = 29 with ≳90% completeness and sample the brightest ∼5% of the GC system. Assuming the well-known Gaussian form of the GC luminosity function (GCLF), we estimate a total population of GCs within a projected radius of 400 kpc. As many as half of the GCs may comprise an intracluster component. Even with the sizable uncertainties, which mainly result from the uncertain GCLF parameters, this system is by far the largest GC population studied to date. The specific frequency SN is high, but not uncommon for central galaxies in massive clusters, rising from SN ≈ 5 near the center to ∼12 at large radii. Passive galaxy fading would increase SN by ∼20% at z = 0. We construct the radial mass profiles of the GCs, stars, intracluster gas, and lensing-derived total mass, and we compare the mass fractions as a function of radius. The estimated mass in GCs, = 3.9 × 1010 Mȯ, is comparable to ∼80% of the total stellar mass of the Milky Way. The shape of the GC mass profile appears intermediate between those of the stellar light and total cluster mass. Despite the extreme nature of this system, the ratios of the GC mass to the baryonic and total masses, and thus the GC formation efficiency, are typical of those in other rich clusters when comparing at the same physical radii. The GC formation efficiency is not constant, but varies with radius, in a manner that appears similar for different clusters; we speculate on the reasons for this similarity in profile. © 2013. The American Astronomical Society. All rights reserved..
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LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Herzberg Institute of Astrophysics (HIA-IHA)
Peer reviewedYes
NPARC number21269672
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Record identifierd1e3d55d-63f2-4db8-bbea-e22a3a967f2c
Record created2013-12-13
Record modified2016-07-18
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