We thank the anonymous referee for providing insightful comments, which have enhanced the clarity of this work. C.B was supported by the University of Wisconsin-Milwaukee's Office of Undergraduate Research through the Support for Undergraduate Research Fellows (SURF) Award and Senior Excellence in Research Award (SERA). C.C.S. and Z.L. were supported in part by U.S. National Science Foundation grant AST-2009278 and by the JPL/Caltech President's and Director's Fund. D.K.E. was supported by the US National Science Foundation (NSF) through Astronomy & Astrophysics grant AST-1909198. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are deeply grateful for the opportunity to conduct observations from this mountain. Authors C.B. and D.K.E. acknowledge in Milwaukee that we are on traditional Potawatomi, Ho-Chunk, and Menominee homeland along the southwest shores of Michigami, North America's largest system of freshwater lakes, where the Milwaukee, Menominee, and Kinnickinnic rivers meet and the people of Wisconsin's sovereign Anishinaabe, Ho-Chunk, Menominee, Oneida, and Mohican nations remain present. We are very grateful for the opportunity to do research in the homelands of these sovereign nations.
Gas Accretion Traced by Blue-dominated Lyα Emission and Redshifted UV Absorption Lines in Protocluster Galaxies at z = 2.3 from the KBSS-KCWI Survey
Creators
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1.
University of Wisconsin–Milwaukee
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2.
Texas A&M University
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3.
California Institute of Technology
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4.
Johns Hopkins University
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5.
University of California, Davis
Abstract
Lyα emission with a dominant blueshifted peak can probe gas flowing through the circumgalactic medium as it accretes onto galaxies and fuels new star formation, although it has seldom actually been observed. Here we present new Keck Cosmic Web Imager observations of the extended Lyα halos surrounding Q1700-BX710 and Q1700-BX711, a pair of UV continuum-selected Keck Baryonic Structure Survey galaxies at z = 2.3 in the HS1700+643 protocluster. We find that BX710's and BX711's Lyα halos are aligned with a large-scale galaxy filament consisting of 13 spectroscopically identified protocluster galaxies. By measuring the peak separation and blue-to-red peak flux ratio of the Lyα emission profiles throughout these galaxies' Lyα halos, we have obtained measurements of their spatially varying velocity structure. The prevalence of blue-dominated Lyα emission profiles throughout BX711's Lyα halo suggests actively accreting gas. We fit a clumpy, multiphase Monte Carlo Radiative Transfer model, which assumes a radially varying clump velocity to the spatially resolved Lyα emission throughout BX710's and BX711's Lyα halos and simultaneously fit these galaxies' average down-the-barrel UV absorption profile with a radially varying velocity model. The results of these models are consistent with a combination of H i and higher-metallicity gas accretion for both galaxies, especially BX711, which exhibits inflow-driven kinematics throughout most of its Lyα halo. We consider various accretion scenarios to explain these findings, including accretion of metal-enriched gas from the cosmic web, galaxy interactions, and recycled gas from the circumgalactic medium, all of which are compatible with our current observations.
Copyright and License
© 2025. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
Additional Information
This paper presents findings from observations conducted at the W.M. Keck Observatory, which is operated as a scientific partner ship among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2408.01598 (arXiv)
- Is supplemented by
- Dataset: 10.17909/j2mb-9350 (DOI)
Funding
- University of Wisconsin–Milwaukee
- National Science Foundation
- AST-2009278
- Jet Propulsion Laboratory
- President's and Director's Fund -
- National Science Foundation
- AST-1909198
- W. M. Keck Foundation
Dates
- Accepted
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2025-01-26
- Available
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2025-03-19Published