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WLM: Dynamics of an isolated dwarf irregular galaxy under ram pressure in the Local Group

Year: 2026
Type: article
Abstract: The Wolf–Lundmark–Melotte (WLM) galaxy is an archetypal dwarf irregular galaxy that has not experienced interactions with major Local Group galaxies within the past 8 Gyr. It has recently been shown that WLM is losing its gas due to ram pressure forces exerted by the surrounding intergalactic medium. In this work, we explored how ram pressure can also affect the WLM gas kinematics, and we show that its dynamics is especially perturbed at its outskirts, which explains the asymmetric rotation between the approaching and receding sides. Moreover, we have been able to decompose WLM into two main components, a compact one with a solid-body rotation that resembles a bar-like structure, and a more extended one with a characteristic double-horn profile suggesting an edge-on disc. The former is relatively unaffected by ram pressure while the dynamics of the latter is considerably affected. This study shows that mass estimates of a dwarf galaxy like WLM should involve a full modelling of its dynamical components, especially its asymmetric rotation curve.
DOI: 10.1051/0004-6361/202557380/pdf
Authors: Neel Kolhe, Francois Hammer, Yanbin Yang, Brenda Namumba, Laurent Chemin, Philippe Amram, Roger Ianjamasimanana, Claude Carignan
Institutions: Centre National de la Recherche Scientifique, Université Paris Sciences et Lettres, Observatoire de Paris, LIRA - Laboratoire d'instrumentation et de recherche en astrophysique, Instituto de Astrofísica de Andalucía, Universidad Andrés Bello, Observatoire astronomique de Strasbourg, Université de Strasbourg, Aix-Marseille Université
Language: English
Open Access status: green
Funders: Ministerio de Ciencia, Innovación y Universidades, European Commission, National Research Foundation, Junta de Andalucía, Instituto de Astrofísica de Andalucía, European Regional Development Fund, Agencia Estatal de Investigación, European Social Fund
Awards: G1092424111, G1105844351, G1171257612, G1175115578, G1735320636, G1889831420, G2016568704, G2065685387, G2262748287, G24120701, G2601397997, G278595929, G294895050, G300979063, G3480869486, G3681454997, G373897614, G3780957795, G3817602061, G3975875632, G4042783231, G410571670, G425668148, G4426983848, G451917667, G463062595, G491712853, G5080475149, G5177886010, G5195188938, G523076202, G5338730000, G5539308778, G5635532810, G5881647929, G5894067328, G593054264, G5965985481, G5967599077, G6033112984, G6218905885, G6359581693, G6880300208, G7084143925, G7127239378, G7395345766, G7434936867, G7805626310, G7863371703, G8497050386, G8667377315, G8888022036, G939699906
OpenAlex ID: W7130946138
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