CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon
Intrinsically faint galaxies at z ∼ 2–3 offer critical insights into early galaxy formation, tracing low-metallicity, low-mass systems during cosmic noon and serving as analogs to reionization-era galaxies. We present ultradeep JWST/NIRSpec spectroscopy of nine low-luminosity galaxies (−17 ≲ M _UV...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/adf4eb |
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| author | Menelaos Raptis Ryan F. Trainor Allison L. Strom Gwen C. Rudie Noah S. J. Rogers Charles C. Steidel Michael V. Maseda Caroline von Raesfeld Nathalie A. Korhonen Cuestas |
| author_facet | Menelaos Raptis Ryan F. Trainor Allison L. Strom Gwen C. Rudie Noah S. J. Rogers Charles C. Steidel Michael V. Maseda Caroline von Raesfeld Nathalie A. Korhonen Cuestas |
| author_sort | Menelaos Raptis |
| collection | DOAJ |
| description | Intrinsically faint galaxies at z ∼ 2–3 offer critical insights into early galaxy formation, tracing low-metallicity, low-mass systems during cosmic noon and serving as analogs to reionization-era galaxies. We present ultradeep JWST/NIRSpec spectroscopy of nine low-luminosity galaxies (−17 ≲ M _UV ≲ −20, M _⋆ ≲ 10 ^9 M _⊙ ) at z ∼ 2.5 from the CECILIA program, with ∼29.5 hr in G235M/F170LP and 1 hr in G395M/F290LP. Our sample includes four Ly α emitters, three rest-UV color-selected galaxies, and two serendipitous detections, providing the most sensitive rest-optical spectra of individual faint galaxies at this epoch to date. Balmer-line measurements reveal low star formation rates (SFRs; 0.63 < SFR/( M _⊙ yr ^−1 ) < 5.43) and a broad range of dust reddening (0 < E ( B − V ) < 1), with SFRs systematically below those of continuum-selected galaxies. Electron densities are low ( n _e ≲ 200 cm ^−3 ), and emission-line diagnostics indicate low [N II ]/H α and high [O III ]/H β , suggesting metallicities of $12+{\mathrm{log}}\,({\rm{O}}/{\rm{H}})\lesssim 8.0$ . We also present the first O1-BPT constraints in such faint high-redshift galaxies. Notably, two galaxies show low [O III ]/H β despite high Ly α EWs and very low [N II ]/H α , consistent with the predicted turnover in this ratio at very low metallicities, highlighting the need for complementary diagnostics (e.g., N2, O32) to identify metal-poor systems. Direct T _e -based abundances and expanded samples are needed to further trace metallicity and ionization trends in low-mass galaxies. |
| format | Article |
| id | doaj-art-4c1f2066f9854e5ea2a37c0d9629a54d |
| institution | Kabale University |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal Letters |
| spelling | doaj-art-4c1f2066f9854e5ea2a37c0d9629a54d2025-08-20T14:48:52ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019892L5510.3847/2041-8213/adf4ebCECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic NoonMenelaos Raptis0https://orcid.org/0009-0008-2226-5241Ryan F. Trainor1https://orcid.org/0000-0002-6967-7322Allison L. Strom2https://orcid.org/0000-0001-6369-1636Gwen C. Rudie3https://orcid.org/0000-0002-8459-5413Noah S. J. Rogers4https://orcid.org/0000-0002-0361-8223Charles C. Steidel5https://orcid.org/0000-0002-4834-7260Michael V. Maseda6https://orcid.org/0000-0003-0695-4414Caroline von Raesfeld7https://orcid.org/0000-0002-6034-082XNathalie A. Korhonen Cuestas8https://orcid.org/0000-0003-2385-9240Department of Physics and Astronomy , Franklin & Marshall College, 637 College Avenue, Lancaster, PA 17603, USADepartment of Physics and Astronomy , Franklin & Marshall College, 637 College Avenue, Lancaster, PA 17603, USA; William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , Baltimore, MD 21218, USACenter for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , 1800 Sherman Avenue, Evanston, IL 60201, USA; Department of Physics and Astronomy, Northwestern University , 2145 Sheridan Road, Evanston, IL 60208, USAThe Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USACenter for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , 1800 Sherman Avenue, Evanston, IL 60201, USACahill Center for Astronomy and Astrophysics, California Institute of Technolog y, MS 249-17, Pasadena, CA 91125, USADepartment of Astronomy, University of Wisconsin–Madison , 475 North Charter Street, Madison, WI 53706, USACenter for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , 1800 Sherman Avenue, Evanston, IL 60201, USA; Department of Physics and Astronomy, Northwestern University , 2145 Sheridan Road, Evanston, IL 60208, USACenter for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University , 1800 Sherman Avenue, Evanston, IL 60201, USA; Department of Physics and Astronomy, Northwestern University , 2145 Sheridan Road, Evanston, IL 60208, USAIntrinsically faint galaxies at z ∼ 2–3 offer critical insights into early galaxy formation, tracing low-metallicity, low-mass systems during cosmic noon and serving as analogs to reionization-era galaxies. We present ultradeep JWST/NIRSpec spectroscopy of nine low-luminosity galaxies (−17 ≲ M _UV ≲ −20, M _⋆ ≲ 10 ^9 M _⊙ ) at z ∼ 2.5 from the CECILIA program, with ∼29.5 hr in G235M/F170LP and 1 hr in G395M/F290LP. Our sample includes four Ly α emitters, three rest-UV color-selected galaxies, and two serendipitous detections, providing the most sensitive rest-optical spectra of individual faint galaxies at this epoch to date. Balmer-line measurements reveal low star formation rates (SFRs; 0.63 < SFR/( M _⊙ yr ^−1 ) < 5.43) and a broad range of dust reddening (0 < E ( B − V ) < 1), with SFRs systematically below those of continuum-selected galaxies. Electron densities are low ( n _e ≲ 200 cm ^−3 ), and emission-line diagnostics indicate low [N II ]/H α and high [O III ]/H β , suggesting metallicities of $12+{\mathrm{log}}\,({\rm{O}}/{\rm{H}})\lesssim 8.0$ . We also present the first O1-BPT constraints in such faint high-redshift galaxies. Notably, two galaxies show low [O III ]/H β despite high Ly α EWs and very low [N II ]/H α , consistent with the predicted turnover in this ratio at very low metallicities, highlighting the need for complementary diagnostics (e.g., N2, O32) to identify metal-poor systems. Direct T _e -based abundances and expanded samples are needed to further trace metallicity and ionization trends in low-mass galaxies.https://doi.org/10.3847/2041-8213/adf4ebGalaxiesHigh-redshift galaxiesLyman-alpha galaxiesDwarf galaxiesEmission line galaxiesGalaxy spectroscopy |
| spellingShingle | Menelaos Raptis Ryan F. Trainor Allison L. Strom Gwen C. Rudie Noah S. J. Rogers Charles C. Steidel Michael V. Maseda Caroline von Raesfeld Nathalie A. Korhonen Cuestas CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon The Astrophysical Journal Letters Galaxies High-redshift galaxies Lyman-alpha galaxies Dwarf galaxies Emission line galaxies Galaxy spectroscopy |
| title | CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon |
| title_full | CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon |
| title_fullStr | CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon |
| title_full_unstemmed | CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon |
| title_short | CECILIA: Ultradeep Rest-optical Spectra of Faint Galaxies at Cosmic Noon |
| title_sort | cecilia ultradeep rest optical spectra of faint galaxies at cosmic noon |
| topic | Galaxies High-redshift galaxies Lyman-alpha galaxies Dwarf galaxies Emission line galaxies Galaxy spectroscopy |
| url | https://doi.org/10.3847/2041-8213/adf4eb |
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