Validating z > 7.5 Lyman Break Galaxy candidates in the COSMOS field with JWST/PASSAGE
Zoke W. Sackih, Mason S. Huberty, Claudia Scarlata, Peter J. Watson, Andrew J. Battisti + 6 more
TLDR
JWST/PASSAGE spectroscopically confirms a z~8 Lyman Break Galaxy, revealing a surprisingly high surface density in the COSMOS field.
Key contributions
- Analyzed 7 candidate z > 7.5 galaxies using JWST/NIRISS spectroscopy.
- Spectroscopically confirmed one Lyman Break Galaxy (LBG) at z=7.962.
- Remaining 6 candidates were too faint for redshift measurement.
- Implied surface density of z~8 galaxies is ~10x higher than previous estimates.
Why it matters
This paper provides crucial spectroscopic confirmation of a very distant galaxy, pushing the boundaries of early universe observation. The discovery of a potential overdensity challenges current models of galaxy formation and distribution at high redshifts.
Original Abstract
We analyze spectroscopy from one NIRISS pointing in the JWST-PASSAGE program for seven candidate $z \gtrsim 7.5$ photometrically-selected COSMOS-Web sources. We spectroscopically confirm one out of seven sources as a Lyman break galaxy (LBG) at $z=7.962^{+0.003}_{-0.006}$, with $m_{F150W} = 25.9$ (AB). The remaining sources are too faint in the continuum (i.e., $m_{F150W} \gtrsim 26$ AB) to provide a redshift measurement from the Lyman break, and do not show emission lines in their spectra. Although this study contains only one spectroscopically confirmed source, the confirmation of a luminous $z \sim 8$ galaxy within this $\sim4.8$ arcmin$^2$ field implies a surface density of $\sim 0.21^{+0.59}_{-0.17}$ arcmin$^{-2}$, $\approx 10\times$ higher than inferred from wide-area photometric surveys, suggesting a potential overdensity at $z\sim8$ in the COSMOS field.
📬 Weekly AI Paper Digest
Get the top 10 AI/ML arXiv papers from the week — summarized, scored, and delivered to your inbox every Monday.