Title
The HST-Hyperion Survey: Grism Observations of a z ∼ 2.5 Protosupercluster
Date Issued
2025
Author(s)
Forrest, Ben
Shen, Lu
Lemaux, Brian C.
Shah, Ekta
Gal, Roy R.
Giddings, Finn
Hu, Weida
Ronayne, Kaila
Sikorski, Derek
Staab, Priti
Amorín, Ricardo O.
Hathi, Nimish
Hung, Denise
Lubin, Lori
Pelliccia, Debora
Ryan, Russell E.
Zamorani, Gianni
DOI
10.3847/1538-4357/adc252
Abstract
We present the first results and catalogs from the HST-Hyperion survey. This survey has collected 50 orbits of WFC3/F160W imaging and WFC3/G141 grism spectroscopy in the most overdense regions of the Hyperion protosupercluster at z ∼ 2.45, which are analyzed in conjunction with the adjacent 56 orbits of WFC3/F140W imaging and WFC3/G141 grism spectroscopy from the 3D-HST survey. Sources were identified and spectra were extracted using GRIZLI, which subsequently fit the combined grism data with object-matched photometric data from the COSMOS2020 catalog to obtain a redshift and best-fit spectral model. Each source was then visually inspected by multiple team members and quality flags were assigned. A total of 12,814 objects with m<SUB>HST</SUB> ≤ 25.0 were inspected, of which 5629 (44%) have reliable redshifts from the grism data and are sensitive to emission lines at a level of ∼8.8 × 10<SUP>‑18</SUP> erg s<SUP>‑1</SUP> cm<SUP>‑2</SUP> (1σ). A comparison with high-quality, ground-based spectroscopic redshifts yields a scatter of σ<SUB>NMAD</SUB> = 0.0016. The resulting catalogs contain 125 confirmed members of the Hyperion structure within 2.40 < z < 2.53, with an additional 71 confirmed galaxies in projection within 2.35 < z < 2.65. The redshift, stellar population, and line flux catalogs, as well as all grism spectra, are publicly available.
Subjects
Protoclusters
Galaxy evolution
1297
594