Document Type

Article

Publication Date

8-1-2017

Publication Title

The Astrophysical Journal Letters

Abstract

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 ± 63kms−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 aCO = 0.8 Me (K km s−1 pc2)−1, we estimate a total molecular gas mass of 1.1 ± 0.1 × 1011 Me and a MH2/Må ∼ 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 Me 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.

Keywords

galaxies: clusters, individual (SpARCS1049+56), galaxies: evolution, galaxies: starburst, ISM: molecules

Volume

844

Issue

L17

DOI

doi.org/10.3847/2041-8213/aa7749

Rights

© 2017. The American Astronomical Society. All rights reserved.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.