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Tentative detection of the circumgalactic medium of the isolated low-mass dwarf galaxy WLM

Zheng, Yong and Putman, Mary E. and Emerick, Andrew and McQuinn, Kristen B. W. and Werk, Jessica K. and Lockman, Felix J. and Oppenheimer, Benjamin D. and Fox, Andrew J. and Kirby, Evan N. and Burchett, Joseph N. (2019) Tentative detection of the circumgalactic medium of the isolated low-mass dwarf galaxy WLM. Monthly Notices of the Royal Astronomical Society, 490 (1). pp. 467-477. ISSN 0035-8711. doi:10.1093/mnras/stz2563.

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We report a tentative detection of the circumgalactic medium (CGM) of Wolf–Lundmark–Melotte (WLM), an isolated, low-mass (logM*/M⊙ ≈ 7.6), dwarf irregular galaxy in the Local Group (LG). We analyse an HST/COS archival spectrum of a quasar sightline (PHL2525), which is 45 kpc (0.5 virial radius) from WLM and close to the Magellanic Stream (MS). Along this sightline, two ion absorbers are detected in Si II, Si III, Si IV, C II, and C IV at velocities of ∼−220 km s⁻¹ (Component v-220) and ∼−150 km s⁻¹ (Component v-150). To identify their origins, we study the position–velocity alignment of the components with WLM and the nearby MS. Near the magellanic longitude of PHL2525, the MS-related neutral and ionized gas moves at ≲−190 km s⁻¹, suggesting an MS origin for Component v-220, but not for Component v-150. Because PHL2525 passes near WLM and Component v-150 is close to WLM’s systemic velocity (∼−132 km s⁻¹), it is likely that Component v-150 arises from the galaxy’s CGM. This results in a total Si mass in WLM’s CGM of M^(CGM)_(Si)∼(0.2−1.0)×10⁵ M⊙ using assumption from other COS dwarf studies. Comparing M^(CGM)_(Si) to the total Si mass synthesized in WLM over its lifetime (∼1.3 × 10⁵ M⊙), we find ∼3 per cent is locked in stars, ∼6 per cent in the ISM, ∼15–77 per cent in the CGM, and the rest (∼14–76 per cent) is likely lost beyond the virial radius. Our finding resonates with other COS dwarf galaxy studies and theoretical predictions that low-mass galaxies can easily lose metals into their CGM due to stellar feedback and shallow gravitational potential.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zheng, Yong0000-0003-4158-5116
Emerick, Andrew0000-0003-2807-328X
Werk, Jessica K.0000-0002-0355-0134
Oppenheimer, Benjamin D.0000-0003-4754-6863
Kirby, Evan N.0000-0001-6196-5162
Burchett, Joseph N.0000-0002-1979-2197
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2019 September 6. Received 2019 July 15; in original form 2019 April 3. Published: 13 September 2019. YZ is grateful to D. Weisz for many useful discussions during the preparation of this work. YZ thanks S. Albers for providing SFH estimates of WLM on combined UVIS/ACS fields, thanks C. F. McKee for his feedback on this manuscript, and thanks C. howk and N. Lehner for their comments on possible origin of the MW ionized high-velocity clouds. YZ acknowledges support from the Miller Institute for Basic Research in Science. AE was supported by the National Science Foundation (NSF) Blue Waters Graduate Fellowship. ENK acknowledges support by NASA through a grant (HST-GO-15156.004-A) from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS 5-26555. The UV spectrum presented in this work was obtained from the Mikulski Archive for Space Telescopes (MAST). Facilities: HST/COS, Green Bank Telescope. Software: ASTROPY (Astropy Collaboration et al. 2013), IDL, NUMPY (Oliphant 2007), MATPLOTLIB (Hunter 2007).
Group:Astronomy Department
Funding AgencyGrant Number
Miller Institute for Basic Research in ScienceUNSPECIFIED
NASANAS 5-26555
Subject Keywords:techniques: spectroscopic – galaxies: dwarf (WLM) – galaxies: haloes – quasars: absorption lines
Issue or Number:1
Record Number:CaltechAUTHORS:20191205-151312615
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Official Citation:Yong Zheng, Mary E Putman, Andrew Emerick, Kristen B W McQuinn, Jessica K Werk, Felix J Lockman, Benjamin D Oppenheimer, Andrew J Fox, Evan N Kirby, Joseph N Burchett, Tentative detection of the circumgalactic medium of the isolated low-mass dwarf galaxy WLM, Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 1, November 2019, Pages 467–477,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100214
Deposited By: Tony Diaz
Deposited On:06 Dec 2019 19:07
Last Modified:16 Nov 2021 17:52

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