Is bright galaxy formation different in the epoch of reionization? Confirmation of the brightest candidates at redshift z>8

Final submission. 1554274968 Assigned ID: 656 ----- Attempting Submission 1 (Wed Jan 30 16:56:24 GMT 2019) ----- HST Phase I Proposal 656 (borg_followup_mc26.apt) successfully submitted. Receipt: # 656-1 ----- Attempting Submission 2 (Wed Jan 30 18:15:06 GMT 2019) ----- HST Phase I Proposal 656 (borg_followup_mc26.apt) successfully submitted. Receipt: # 656-2 ----- Attempting Submission 3 (Wed Jan 30 21:51:13 GMT 2019) ----- HST Phase I Proposal 656 (borg_followup_mc26.apt) successfully submitted. Receipt: # 656-3 0 ----- Attempting Submission 1 (Wed Apr 17 15:35:38 GMT 2019) ----- Is bright galaxy formation different in the epoch of reionization? Confirmation of the brightest candidates at redshift z>8 How did bright galaxies evolve in the early universe? How much did they contribute to cosmic reionization? These questions have been intensively asked in the modern astronomy. Studying galaxy luminosity functions (LFs) over the cosmic time is a key approach for progress before JWST. Recent studies at z>7 reported a possible evidence of deviation from the Schechter form LF, with an excess at the bright end. Indeed, previous spectroscopic confirmation of two very luminous galaxies at z=8.68 and z=11.09 seems to support the argument, and dramatically changed our understanding of the universe and galaxy evolution in the early universe. In this program, we aim at confirmation of 4, very bright, galaxy candidates at z>8, just identified from the Brightest of Reionizing Galaxies (BoRG), a pure-parallel HST observing program, which is acquiring 1000 pure-parallel orbits with WFC3 in cycles 22 and 25. Among all photometric sources collected in 106 independent HST line-of-sights, the four high-quality photometric sources are exceptionally bright (m125=24.1-25.3, or MUV~-23 to -22 if confirmed at z>8). Addition of a single orbit WFC3IR/F098M imaging for each field will significantly improve their photometric redshift estimate, efficiently differentiating if they are genuine high-z galaxies or low-z interlopers. With the redshift confirmation, we will gain insight into the early evolution of galaxy from the shape of refined LFs, as well as construct a promising high-z sample for future spectroscopic observations by JWST. The observations consist of four 1-orbit visits of F098M imaging (4 exposures times 4 fields). We selected 4 13-NSAMP SPARS50 exposures to fill the orbit in each field, using a 4-point minimum box with optimal half-pixel sampling in both x and y. The field centers are matched to previous observations with the same instrument, and so as orientations but are flexible among every 90 degree. Galaxies and the IGM 3 false false false false false false false SUPPORTED GALAXY STARBURST J2000 J2000 m125=25.3 (ABmag) GALAXY STARBURST J2000 J2000 m125=24.1 (ABmag) GALAXY STARBURST J2000 J2000 m125=24.9 (ABmag) GALAXY STARBURST J2000 J2000 m125=24.2 (ABmag) WFC3/IR Imaging No No F098M WFC3/IR Imaging No No F098M WFC3/IR Imaging No No F098M WFC3/IR Imaging No No F098M POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 1

false

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