2021ApJ...921...68K -
Astrophys. J., 921, 68-68 (2021/November-1)
The nature of HI-absorption-selected galaxies at z ≃ 4.
KAUR B., KANEKAR N., RAFELSKI M., NEELEMAN M., REVALSKI M. and PROCHASKA J.X.
Abstract (from CDS):
We report a Karl G. Jansky Very Large Array (JVLA) search for redshifted CO(1-0) or CO(2-1) emission, and a Hubble Space Telescope Wide Field Camera 3 (HST-WFC3) search for rest-frame near-ultraviolet (NUV) stellar emission, from seven HI-selected galaxies associated with high-metallicity ([M/H] >= -1.3) damped Lyα absorbers (DLAs) at z ≃ 4. The galaxies were earlier identified by Atacama Large Millimeter/submillimeter Array imaging of their [CII] 158 µm emission. We also used the JVLA to search for CO(2-1) emission from the field of a low-metallicity ([M/H] = -2.47) DLA at z ≃ 4.8. No statistically significant CO emission is detected from any of the galaxies, yielding upper limits of Mmol < (7.4-17.9) x 1010 x (αCO/4.36) M☉ on their molecular gas mass. We detect rest-frame NUV emission from four of the seven [CII] 158 µm-emitting galaxies, the first detections of the stellar continuum from HI-selected galaxies at z >= 4. The HST-WFC3 images yield typical sizes of the stellar continua of ≃2-4 kpc and inferred dust-unobscured star formation rates (SFRs) of ≃5.0-17.5 M☉ yr–1, consistent with, or slightly lower than, the total SFRs estimated from the far-infrared (FIR) luminosity. We further stacked the CO(2-1) emission signals of six [CII] 158 µm-emitting galaxies in the image plane. Our non-detection of CO(2-1) emission in the stacked image yields the limit Mmol < 4.1 x 1010 x (αCO/4.36) M☉ on the average molecular gas mass of the six galaxies. Our molecular gas mass estimates and NUV SFR estimates in HI-selected galaxies at z ≃ 4 are consistent with those of main-sequence galaxies with similar [CII] 158 µm and FIR luminosities at similar redshifts. However, the NUV emission in the HI-selected galaxies appears more extended than that in main-sequence galaxies at similar redshifts.
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Galaxies - High-redshift galaxies
Simbad objects:
8
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