RELICS: Small-scale Star Formation in Lensed Galaxies at z=610

Brian Welch, Dan Coe, Adi Zitrin, Jose M. Diego, Rogier Windhorst, Nir Mandelker, Eros Vanzella, Swara Ravindranath, Erik Zackrisson, Michael Florian, Larry Bradley, Keren Sharon, Maruša Bradač, Jane Rigby, Brenda Frye, Seiji Fujimoto

Submitted on 7 July 2022


Detailed observations of star forming galaxies at high redshift are critical to understand the formation and evolution of the earliest galaxies. Gravitational lensing provides an important boost, allowing observations at physical scales unreachable in unlensed galaxies. We present three lensed galaxies from the RELICS survey at zphot=610, including the most highly magnified galaxy at zphot6 (WHL0137-zD1, dubbed the Sunrise Arc), the brightest known lensed galaxy at zphot6 (MACS0308-zD1), and the only spatially resolved galaxy currently known at zphot10 (SPT0615-JD). The Sunrise Arc contains seven star-forming clumps with delensed radii as small as 3 pc, the smallest spatial scales yet observed in a z>6 galaxy, while SPT0615-JD contains features measuring a few tens of parsecs. MACS0308-zD1 contains a r30 pc clump with a star formation rate (SFR) of 3M yr1, giving it a SFR surface density of ΣSFR103M yr1 kpc2. These galaxies provide a unique window into small scale star formation during the Epoch of Reionization. They will be excellent targets for future observations with JWST, including one approved program targeting the Sunrise Arc.


Comment: 15 pages, 7 figures, submitted to ApJ

Subject: Astrophysics - Astrophysics of Galaxies