AR 14300 (Archival Research)

Wed Jul 24 19:32:25 GMT 2024

Principal Investigator: Rachael Livermore
PI Institution: University of Melbourne
Investigators (xml)

Title: Searching for faint high-z galaxies in the Hubble Frontier Fields
Cycle: 23

We request funding to support the study of the complete data from the Hubble Frontier Fields (HFF) program. We have developed a method for detecting the faintest lensed galaxies in the cluster fields using wavelet decomposition, and propose to use these data to study several key science areas: 1) The faint end of the rest-frame ultraviolet (UV) luminosity function at z=7-8: We will improve the estimates of the faint-end slope, which remains poorly constrained. The lensing fields will probe luminosities <<0.1L*, while the blank fields will increase the number of <0.5L* galaxies by a factor of 3x. By the completion of the HFF survey, we expect to be able to measure the faint-end slope to within 10%, honing in on the contribution of galaxies to reionization. 2) The colors of faint galaxies: The HFF will probe low-metallicity stars at high-z. The cluster fields will yield galaxies with intrinsic absolute magnitudes fainter than -17, where we expect to see low-metallicity star formation, and the blank fields will increase the numbers of m=28-29 galaxies by 3x, strongly reducing the uncertainty on their mean color. 3) The abundance of galaxies at z=9: The inclusion of the F140W filter in all HFF observations will allow the robust two-band detection of z=9 galaxies. Using a larger sample over a wider dynamic range in luminosity, we will investigate the apparent discrepancy between previous studies at z=9 based on the HUDF. With funding to carry out this work on the complete dataset, we will be able to place the most robust constraints yet on these high-z galaxies, maximizing the output from the HFF program in advance of JWST.