Astrophys. J., 844, L17-L17 (2017/August-1)
Detection of a substantial molecular gas reservoir in a brightest cluster galaxy at z = 1.7.
WEBB T.M.A., LOWENTHAL J., YUN M., NOBLE A.G., MUZZIN A., WILSON G., YEE H.K.C., CYBULSKI R., ARETXAGA I. and HUGHES D.H.
Abstract (from CDS):
We report the detection of CO(2-1) emission coincident with the brightest cluster galaxy (BCG) of the high-redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091 ± 0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well fit by a single-component Gaussian with an RSR-resolution-corrected FWHM of 569 ± 63 km s–1. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen in near-infrared imaging with the Hubble Space Telescope. We measure the integrated flux of the line to be 3.6 ± 0.3 Jy km s–1, and using αCO = 0.8 M☉(K km s–1 pc2)–1, we estimate a total molecular gas mass of 1.1 ± 0.1 x 1011 M☉ and a MH2/M* ∼ 0.4. This is the largest gas reservoir detected in a BCG above z > 1 to date. Given the infrared-estimated star formation rate of 860 ± 130 M☉ yr–1, this corresponds to a gas depletion timescale of ∼0.1 Gyr. We discuss several possible mechanisms for depositing such a large gas reservoir to the cluster center-e.g., a cooling flow, a major galaxy-galaxy merger, or the stripping of gas from several galaxies-but conclude that these LMT data are not sufficient to differentiate between them.
© 2017. The American Astronomical Society. All rights reserved.
galaxies: clusters: individual: SpARCS1049+56 - galaxies: evolution - galaxies: starburst - ISM: molecules - ISM: molecules
SpARCS J104922+564032 BCG is not in SIMBAD.
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