Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies

[2607.24071] Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies Skip to main content Search Submit Donate Log in Search arXiv Press Enter to search · Advanced search Astrophysics > Astrophysics of Galaxies arXiv:2607.24071 (astro-ph) [Submitted on 27 Jul 2026 ( v1 ), last revised 15 Aug 2026 (this version, v2)] Title: Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies Authors: Xuanyi Wu , Cheng Li View a PDF of the paper titled Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies, by Xuanyi Wu and Cheng Li View PDF HTML (experimental) Abstract: We use luminous red galaxies (LRGs) and background quasar spectra from DESI DR1 to measure the mean MgII equivalent width around massive quiescent galaxies as a function of projected radius and azimuth relative to the projected major axis. Our forced-measurement approach assigns a MgII doublet-window EW to every LRG-quasar pair, including spectra without individually detected absorbers, and subtracts a redshift-matched random-control signal measured from the same normalized quasar spectra. The all-angle profile declines smoothly over $r_p=0.01$-$1.0$ proper Mpc and shows stronger inner absorption at $0.4<z_{\rm LRG}<0.75$ than at $0.75<z_{\rm LRG}<1.1$. Superposed on this radial and redshift dependence, sightlines near the LRG major axis show enhanced absorption relative to the minor axis at $r_p\simeq30$-$80$ kpc. For the full $0.4<z_{\rm LRG}<1.1$ sample, the integrated fiducial major-minus-minor difference over $r_p=0.03$-$0.077$ Mpc is $0.184\pm0.075$ Angstrom, with a position-angle randomization probability $p=0.013$. The redshift split shows no significant evolution in the anisotropy amplitude, even though the inner EW profile itself evolves. Our results provide evidence for a localized major-axis enhancement of MgII-bearing cool/warm gas around LRGs, showing that azimuthal CGM structure is measurable in massive quiescent halos as well as in star-forming systems. Comments: 10 pages, 5 figures, 3 table, resubmitted to ApJ Subjects: Astrophysics of Galaxies (astro-ph.GA) Cite as: arXiv:2607.24071 [astro-ph.GA] (or arXiv:2607.24071v2 [astro-ph.GA] for this version) https://doi.org/10.48550/arXiv.2607.24071 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Cheng Li [ view email ] [v1] Mon, 27 Jul 2026 07:15:38 UTC (255 KB) [v2] Sat, 15 Aug 2026 01:07:48 UTC (266 KB) Full-text links: Access Paper: View a PDF of the paper titled Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies, by Xuanyi Wu and Cheng Li View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.GA < prev | next > new | recent | 2026-07 Change to browse by: astro-ph References & Citations NASA ADS Google Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab) Major funding support from

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