Discovery of a Damped Lyα Absorber Originating in a Spectacular Interacting Dwarf Galaxy Pair at z = 0.026
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- Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Chicago, IL (United States)
- Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune (India)
- Univ. of Chicago, IL (United States)
- South African Radio Astronomy Observatory (South Africa); Rhodes Univ., Makhanda (South Africa); Max Planck Institute for Radio Astronomy (Germany)
- Carnegie Observatories, Pasadena, CA (United States)
- University of Milan-Bicocca (Italy)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Russian Academy of Sciences (RAS), St. Petersburg (Russian Federation). Ioffe Physical-Technical Institute; Higher School of Economics (HSE) (Russian Federation)
- Sorbonne Univ., Paris (France); Centre National de la Recherche Scientifique (CNRS) (France); Observatoire de Paris (France)
- Univ. of Hawaii, Hilo, HI (United States)
- Northwestern Univ., Evanston, IL (United States)
- Univ. of Geneva (Switzerland)
- University of Chile, Santiago (Chile)
- National Radio Astronomy Observatory, Socorro, NM (United States)
- Paris Institute of Astrophysics (France); Centre National de la Recherche Scientifique (CNRS) (France); University of Chile, Santiago (Chile)
- Paris Institute of Astrophysics (France); Centre National de la Recherche Scientifique (CNRS) (France)
- Space Telescope Science Institute, Baltimore, MD (United States); Johns Hopkins Univ., Baltimore, MD (United States)
We present the discovery of neutral gas detected in both damped Lyα absorption (DLA) and H I 21 cm emission outside of the stellar body of a galaxy, the first such detection in the literature. A joint analysis between the Cosmic Ultraviolet Baryon Survey and the MeerKAT Absorption Line Survey reveals an H I bridge connecting two interacting dwarf galaxies (log (Mstar/M⊙) = 8.5 ± 0.2) that host a z = 0.026 DLA with log[N(H I)/cm–2] = 20.60 ± 0.05 toward the QSO J2339–5523 (zQSO = 1.35). At impact parameters of d = 6 and 33 kpc, the dwarf galaxies have no companions more luminous than ≈0.05L* within at least Δv = ±300 km s–1 and d ≈ 350 kpc. The H I 21 cm emission is spatially coincident with the DLA at the 2σ–3σ level per spectral channel over several adjacent beams. However, H I 21 cm absorption is not detected against the radio-bright QSO; if the background UV and radio sources are spatially aligned, the gas is either warm or clumpy (with a spin temperature to covering factor ratio Ts/fc > 1880 K). Observations with VLT-MUSE demonstrate that the α-element abundance of the ionized interstellar medium (ISM) is consistent with the DLA (≈10% solar), suggesting that the neutral gas envelope is perturbed ISM gas. This study showcases the impact of dwarf–dwarf interactions on the physical and chemical state of neutral gas outside of star-forming regions. In the SKA era, joint UV and H I 21 cm analyses will be critical for connecting the cosmic neutral gas content to galaxy environments.
- Research Organization:
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
- Sponsoring Organization:
- National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0014664
- OSTI ID:
- 1983320
- Journal Information:
- The Astrophysical Journal. Letters, Journal Name: The Astrophysical Journal. Letters Journal Issue: 2 Vol. 926; ISSN 2041-8205
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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