IDCS J1426.5+3508: THE MOST MASSIVE GALAXY CLUSTER AT z > 1.5
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Brodwin-2016-IDCS J1426.5+3508_ T.pdf
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Author(s)
Brodwin, Mark
Gonzalez, Anthony H.
Stanford, S. A.
Eisenhardt, Peter R.
Stern, Daniel
Zeimann, Gregory R.
McDonald, Michael A.
Date Issued
January 2016
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Brodwin, Mark, Michael McDonald, Anthony H. Gonzalez, S. A. Stanford, Peter R. Eisenhardt, Daniel Stern, and Gregory R. Zeimann. “ IDCS J1426.5+3508: THE MOST MASSIVE GALAXY CLUSTER AT z > 1.5 .” The Astrophysical Journal 817, no. 2 (January 27, 2016): 122. © 2016 The American Astronomical Society
Version
Final published version
Abstract
We present a deep (100 ks) Chandra observation of IDCS J1426.5+3508, a spectroscopically confirmed, infrared-selected galaxy cluster at z = 1.75. This cluster is the most massive galaxy cluster currently known at z > 1.5, based on existing Sunyaev–Zel'dovich (SZ) and gravitational lensing detections. We confirm this high mass via a variety of X-ray scaling relations, including T[subscript X]–M, f[subscript g]–M, Y[subscript X]–M, and L[subscript X]–M, finding a tight distribution of masses from these different methods, spanning M[subscript 500] = 2.3–3.3 × 10[superscript 14]M[subscript ⊙], with the low-scatter Y[subscript X]-based mass M[subscript 500,Y[subscript X]] = 2.6[+1.5 over -0.5] x 10[superscript 14] M[subscript ⊙]. IDCS J1426.5+3508 is currently the only cluster at z > 1.5 for which X-ray, SZ, and gravitational lensing mass estimates exist, and these are in remarkably good agreement. We find a relatively tight distribution of the gas-to-total mass ratio, employing total masses from all of the aforementioned indicators, with values ranging from f[subscript gas,500] = 0.087–0.12. We do not detect metals in the intracluster medium (ICM) of this system, placing a 2σ upper limit of Z(r < R[subscript 500]) < 0.18 Z[subscript ⊙]. This upper limit on the metallicity suggests that this system may still be in the process of enriching its ICM. The cluster has a dense, low-entropy core, offset by ~30 kpc from the X-ray centroid, which makes it one of the few "cool core" clusters discovered at z > 1, and the first known cool core cluster at z > 1.2. The offset of this core from the large-scale centroid suggests that this cluster has had a relatively recent ([< over ~]500 Myr) merger/interaction with another massive system.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.3847/0004-637x/817/2/122
