A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): JWST Discovers an Overdensity around a Metal Absorption-selected Galaxy at z ∼ 5.5

Yunjing Wu, Feige Wang, Zheng Cai, Xiaohui Fan, Kristian Finlator, Jinyi Yang, Joseph F. Hennawi, Fengwu Sun, Jaclyn B. Champagne, Xiaojing Lin, Zihao Li, Zuyi Chen, Eduardo Bañados, George D. Becker, Sarah E.I. Bosman, Gustavo Bruzual, Stephane Charlot, Hsiao Wen Chen, Jacopo Chevallard, Anna Christina EilersEmanuele Paolo Farina, Xiangyu Jin, Hyunsung D. Jun, Koki Kakiichi, Mingyu Li, Weizhe Liu, Maria A. Pudoka, Wei Leong Tee, Zhang Liang Xie, Siwei Zou

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The launch of JWST opens a new window for studying the connection between metal-line absorbers and galaxies at the end of the Epoch of Reionization. Previous studies have detected absorber-galaxy pairs in limited quantities through ground-based observations. To enhance our understanding of the relationship between absorbers and their host galaxies at z > 5, we utilized the NIRCam wide-field slitless spectroscopy to search for absorber-associated galaxies by detecting their rest-frame optical emission lines (e.g., [O III] + Hβ). We report the discovery of a Mg ii-associated galaxy at z = 5.428 using data from the JWST ASPIRE program. The Mg ii absorber is detected on the spectrum of quasar J0305-3150 with a rest-frame equivalent width of 0.74 Å. The associated galaxy has an [O III] luminosity of 1042.5 erg s−1 with an impact parameter of 24.9 pkpc. The joint Hubble Space Telescope-JWST spectral energy distribution (SED) implies a stellar mass and star formation rate of M * ≈ 108.8 M , star-formation rate ≈ 10 M yr−1. Its [O III] equivalent width and stellar mass are typical of [O III] emitters at this redshift. Furthermore, connecting the outflow starting time to the SED-derived stellar age, the outflow velocity of this galaxy is ∼300 km s−1, consistent with theoretical expectations. We identified six additional [O III] emitters with impact parameters of up to ∼300 pkpc at similar redshifts (∣dv∣ < 1000 km s−1). The observed number is consistent with that in cosmological simulations. This pilot study suggests that systematically investigating the absorber-galaxy connection within the ASPIRE program will provide insights into the metal-enrichment history in the early Universe.

Original languageEnglish (US)
Article numberL40
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Oct 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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