New Star Forming Galaxies at z\approx 7 from WFC3 Imaging

TL;DR

This paper reports the discovery of 29 new star-forming galaxy candidates at redshift around 7 using WFC3 imaging, significantly expanding the sample size and confirming the evolution of galaxy luminosity at this epoch.

Contribution

It introduces a new, larger sample of z~7 galaxy candidates, leveraging WFC3's enhanced NIR sensitivity to improve understanding of early galaxy formation.

Findings

29 new z~7 galaxy candidates identified

Confirmed evolution of the bright end of the luminosity function

Doubling of the robust sample size compared to previous studies

Abstract

The addition of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) has led to a dramatic increase in our ability to study the z>6 Universe. The increase in the near-infrared (NIR) sensitivity of WFC3 over previous instruments has enabled us to reach apparent magnitudes approaching 29 (AB). This allows us to probe the rest-frame ultraviolet (UV) continuum, redshifted into the NIR at $z>6$. Taking advantage of the large optical depths at this redshift, resulting in the Lyman-alpha break, we use a combination of WFC3 imaging and pre-existing Advanced Camera for Surveys (ACS) imaging to search for z approx 7 over 4 fields. Our analysis reveals 29 new z approx 7 star forming galaxy candidates in addition to 16 pre-existing candidates already discovered in these fields. The improved statistics from our doubling of the robust sample of z-drop candidates confirms the previously observed evolution of the bright end of the luminosity function.