Constraints on the galaxy "main sequence" at z>5: the stellar mass of HDF850.1

TL;DR

This study investigates the stellar mass and star formation rate of the high-redshift galaxy HDF850.1, providing new constraints on galaxy properties during the early universe at z>5.

Contribution

It offers the first robust stellar mass estimate for HDF850.1 at z>5, refining previous assumptions and demonstrating a higher specific star formation rate than UV-selected galaxies.

Findings

Stellar mass of HDF850.1 is approximately 2.5x10^{11} solar masses.

Detected specific star formation rate is 8.5 Gyr^{-1}.

The K-band source previously thought to be associated is likely spurious.

Abstract

We present rest-frame optical and near-infrared detections of one of the highest redshift submm-selected galaxies to date, HDF850.1. We do not detect the previously proposed counterpart HDF850.1K in new deep J and H-band HST WFC3 data, placing a strong limit of H-K>3.8, concluding that the K-band source is spurious. However, we detect 5.8um and 8um emission co-located with the submm in deblended images. After modelling and removing the flux contributions from another foreground galaxy, we constrain the stellar mass of HDF850.1 to be (2.5+/-1)x10^{11} Msun/mu for a lensing magnification mu=1.9+/-0.3, with a specific star formation rate of 8.5 Gyr^{-1}, faster than the 1-4 Gyr^{-1} observed for UV-selected galaxies at this epoch.