Kinematically Complex Circumgalactic Gas Around a Low-mass Galaxy: Filamentary Inflow and Counterrotation in J0910b

Zeren Lin; D. Christopher Martin; Mateusz Matuszewski; James D. Neill; Drew M. Miles; Vincent Picouet; Nikolaus Z. Prusinski; Keri Hoadley; Rosalie Mcgurk

doi:10.3847/1538-4357/ae10b2

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Kinematically Complex Circumgalactic Gas Around a Low-mass Galaxy: Filamentary Inflow and Counterrotation in J0910b

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Kinematically Complex Circumgalactic Gas Around a Low-mass Galaxy: Filamentary Inflow and Counterrotation in J0910b

Zeren Lin, D. Christopher Martin, Mateusz Matuszewski, James D. Neill, Drew M. Miles, Vincent Picouet, Nikolaus Z. Prusinski, Keri Hoadley and Rosalie Mcgurk

The Astrophysical journal, Vol.995(1), 12

12/10/2025

DOI: 10.3847/1538-4357/ae10b2

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Abstract

We present the first detailed, spatially resolved study of the circumgalactic medium (CGM) surrounding the low-mass, low-redshift star-forming galaxy J0910b (SDSS J091458.61+110845.1; M star similar to 109.2 M circle dot, z = 0.096), focusing on its gas dynamics, ionization mechanisms, and kinematics. J0910b is the lowest-mass galaxy in our low-redshift CGM survey using the Keck Cosmic Web Imager (KCWI). Using KCWI integral field spectroscopy and CLOUDY modeling, we map the ionization structure and velocity field of the CGM through H alpha, [O III] lambda 5007, and [O II] lambda lambda 3727, 3729 emission. We detect a predominantly cool (T similar to 104 K) ionized halo extending to similar to 35 kpc (similar to 0.35 Rvir), with a complex structure including a counterrotating component and two filamentary inflows. The counterrotating CGM contains similar to 7.4 x 109 M circle dot of ionized gas-nearly 5 times the stellar mass-and exhibits a positive radial metallicity gradient, rising from 0.2 Z circle dot at 9 kpc to 0.65 Z circle dot at 16 kpc. Velocity dispersion maps reveal a shell-like structure near the interstellar medium-CGM interface, suggesting feedback-driven outflows that redistributed enriched gas. In contrast, the filaments show low metallicities (similar to 0.07 Z circle dot), high specific angular momentum (j similar to 3.7 x 103 kpc km s-1), and an accretion rate of 0.05 M circle dot yr-1, consistent with an intergalactic origin. Together, these components reveal a dynamically rich CGM. The counterrotating gas dominates the halo's mass, accounts for similar to 33% of the cosmic baryon budget, and must be continuously replenished (tcool similar to 0.3-2 Myr). These results suggest a long-lived, regulated CGM that governs star formation through angular momentum exchange and gas recycling.

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Title: Subtitle: Kinematically Complex Circumgalactic Gas Around a Low-mass Galaxy: Filamentary Inflow and Counterrotation in J0910b
Creators: Zeren Lin - California Institute of Technology
D. Christopher Martin - California Institute of Technology
Mateusz Matuszewski - California Institute of Technology
James D. Neill - California Institute of Technology
Drew M. Miles - California Institute of Technology
Vincent Picouet - California Institute of Technology
Nikolaus Z. Prusinski - California Institute of Technology
Keri Hoadley - University of Florida
Rosalie Mcgurk - William & Mary
Resource Type: Journal article
Publication Details: The Astrophysical journal, Vol.995(1), 12
DOI: 10.3847/1538-4357/ae10b2
ISSN: 0004-637X
eISSN: 1538-4357
Publisher: IOP Publishing Ltd
Number of pages: 39
Grant note: 80NSSC22K1649 / NASA divided by SMD divided by Astrophysics Division (AD)
Language: English
Date published: 12/10/2025
Academic Unit: Physics and Astronomy
Record Identifier: 9985091805802771

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