We present the BoRG-JWST survey, a combination of two JWST Cycle 1 programs aimed at obtaining NIRSpec spectroscopy of representative, UV-bright 7<z<10 galaxy candidates across 22 independent sight lines selected from Hubble/WFC3 pure-parallel observations. We confirm the high-z nature of 10 out of 19 observed primary targets through low-resolution prism observations, with the rest revealing themselves unsurprisingly to be z∼1−3 interlopers, brown dwarfs, or yielding inconclusive results. From the MSA observations, we confirm an additional 9 filler sources at z>5, highlighting the large abundance of high-redshift galaxies even in individual WFC3 pointings. The primary sample span an absolute magnitude range −20.4<MUV<−22.4 mag and harbour UV continuum slopes of β≃−2.5 to −2.0, representing some of the most luminous z>7 sources currently known and comparable to the brightest sources at z>10. Prominent [O III]+Hβ lines are found across the full sample, while a stack of sources reveals a plethora of other rest-optical lines and additional rest-UV C III]1909 \r{A} emission. Despite their luminosities, none of the low-resolution spectra display evidence for Type 1 AGN activity based on a search for broad-line emission. Lastly, we present a spectroscopic data release of 188 confirmed 0.5≲z≲5.0 sources from filler MSA observations, highlighting the legacy value of the survey and a representative benchmark for comparisons to deep field observations.
@article{arxiv.2407.17551,
title = {The BoRG-JWST Survey: Program Overview and First Confirmations of Luminous Reionization-Era Galaxies from Pure-Parallel Observations},
author = {Guido Roberts-Borsani and Micaela Bagley and Sofía Rojas-Ruiz and Tommaso Treu and Takahiro Morishita and Steven L. Finkelstein and Michele Trenti and Pablo Arrabal Haro and Eduardo Bañados and Óscar A. Chávez Ortiz and Katherine Chworowsky and Taylor A. Hutchison and Rebecca L. Larson and Nicha Leethochawalit and Gene C. K. Leung and Charlotte Mason and Rachel S. Somerville and Massimo Stiavelli and L. Y. Aaron Yung and Susan A. Kassin and Christian Soto},
journal= {arXiv preprint arXiv:2407.17551},
year = {2024}
}