Ram pressure candidates in UNIONS

Ian Roberts , Laura Parker , Stephen Gwyn , Michael Hudson , Raymond Carlberg , Alan Mcconnachie , Jean-Charles Cuillandre , Kenneth Chambers , Pierre-Alain Duc (1) , Hisanori Furusawa , Raphael Gavazzi , Vanessa Hill (2) , Mark Huber , Rodrigo Ibata (1) , Martin Kilbinger , Simona Mei , Yannick Mellier , Satoshi Miyazaki , Masamune Oguri , Richard Wainscoat

1 ObAS - Observatoire astronomique de Strasbourg
2 LAGRANGE - Joseph Louis LAGRANGE

Abstract We present a search for disturbed, candidate ram pressure stripping galaxies across more than 50 spectroscopically selected SDSS groups and clusters. Forty-eight ram pressure candidates are visually identified in these systems using high quality UNIONS imaging from the Canada-France Hawaii Telescope, covering ∼6200 deg2 and ∼2800 deg2 in the u- and r-bands respectively. Ram pressure candidates are found in groups and clusters spanning a wide range in halo mass and include ∼30 ram pressure candidates in the group regime (Mh < 1014). The observed frequency of ram pressure candidates shows substantial scatter with group/cluster mass, but on average is larger in clusters (Mh ≥ 1014 M⊙) than groups (Mh < 1014 M⊙) by a factor of ∼2. We find that ram pressure candidates are most commonly low-mass galaxies and have enhanced star formation rates relative to star-forming field galaxies. The enhancement in star formation is largely independent of galaxy mass and strongest for galaxies in clusters. As a result of the large survey footprint and excellent image quality from UNIONS, we are able to identify disturbed galaxies, potentially affected by ram pressure stripping, across a wide range of host environment.

Domaines: Planète et Univers [physics]

Ian Roberts, Laura Parker, Stephen Gwyn, Michael Hudson, Raymond Carlberg, et al.. Ram pressure candidates in UNIONS. Monthly Notices of the Royal Astronomical Society, 2021, ⟨10.1093/mnras/stab3101⟩. ⟨hal-03421079⟩