2023/12/08 by Gareth C. Jones, Jones, G. C., Joris Witstok +5 · 1 citation
Engineering · Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Phase Equilibria and Thermodynamics
paper · pdf · doi:10.48550/arxiv.2312.05012
openalex publication_date 2023/12/08 · openalex created_date 2023/12/12 · openalex updated_date 2026/07/30
As the primary fuel for star formation, molecular gas plays a key role in galaxy evolution. A number of techniques have been used for deriving the mass of molecular reservoirs in the early Universe (e.g., [CII]158μm, [CI], dust continuum), but the standard approach of CO-based estimates has been limited to a small number of galaxies due to the intrinsic faintness of the line. We present Jansky Very Large Array (JVLA) observations of the z∼8.31 galaxy MACS0416Y1, targeting CO(2-1) and rest-frame radio continuum emission, which result in upper limits on both quantities. Adding our continuum limit to the published far-infrared (FIR) spectral energy distribution (SED), we find a small non-thermal contribution to the FIR emission, a low dust mass (\rmlog10(MD/M\odot)∼5), and an abnormally high dust temperature (\rm TD\gtrsim90K) that may indicate a recent starburst. Assuming a low metallicity (Z/Z\odot∼0.25), we find evidence for M\rm H2,CO\lesssim1010M\odot, in agreement with previous [CII] investigations (M\rm H2,[CII]∼109.6M\odot). Upcoming JWST observations of this source will result in a precise determination of Z, enabling better constraints and an unprecedented view of the gaseous reservoir in this primordial starburst galaxy.