The NIRISS PASSAGE Spectroscopic Redshift Catalog in COSMOS

Journal article

We present the Parallel Application of Slitless Spectroscopy to Analyze Galaxy Evolution (PASSAGE) spectroscopic redshift catalog in the COSMOS field. PASSAGE is a JWST Cycle 1 Near Infrared Imager and Slitless Spectrograph (or NIRISS) wide-field slitless spectroscopy pure-parallel survey, obtaining near-infrared spectra of thousands of extragalactic sources. Fifteen out of 63 PASSAGE fields fall within the Hubble Space Telescope COSMOS footprint, of which 11 overlap with COSMOS-Web, a JWST treasury survey providing additional space-based photometry. We present our custom line-finding algorithm and visual inspection effort used to identify emission lines and derive the spectroscopic redshifts for line-emitting sources in PASSAGE. The line-finding algorithm identifies between ∼200 and 950 line-emitting candidates per field, of which typically 47% were identified as true emission lines post visual inspection. We identify 2183 emission-line sources at 0.08 ≲ z ≲ 4.7, 1896 of which have available COSMOS photometric redshifts. We find excellent redshift agreement between the COSMOS photometric redshifts and the PASSAGE spectroscopic redshifts for strong (signal-to-noise ratio > 5), multi-line-emitting sources. This agreement weakens for PASSAGE single-line emitters with ambiguous identities. These single-line emitters are likely misidentified around 18% of the time based on comparisons to photometric redshifts. We derive stellar masses using PASSAGE photometry and spectroscopic redshifts, in broad agreement with existing COSMOS-Web stellar masses, but with some discrepancy driven by redshift disagreements. We publicly release this spectroscopic redshift catalog, which will enable community-led science in prime extragalactic fields and serve as a crucial dataset for validating Euclid and Roman spectroscopy.

Authors: Huberty, MS; Nedkova, KV; Sattari, Z; Mehta, V; Scarlata, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal: Supplement Series
• Volume: 284
• Issue: 2
• Pages: 64
• Article number: 64
• Publication date: 2026-06-02
• Acceptance date: 2026-04-28
• DOI: 10.3847/1538-4365/ae6777
• EISSN: 1538-4365
• ISSN: 0067-0049
• Language: English
• Keywords: Redshift surveys; Galaxy spectroscopy; Spectroscopy; Near infrared astronomy