The effects of ram-pressure stripping on the internal kinematics of simulated spiral galaxies

Abstract

Aims. We investigate the influence of ram-pressure stripping on the internal gas kinematics of simulated spiral galaxies. Additional emphasis is put on the question of how the resulting distortions of the gaseous disc are visible in the rotation curve and/or the full 2D velocity field of galaxies at different redshifts. Methods. A Milky-Way type disc galaxy is modelled in combined N-body/hydrodynamic simulations with prescriptions for cooling, star formation, stellar feedback, and galactic winds. This model galaxy moves through a constant density and temperature gas, which has parameters similar to the intra-cluster medium (ICM). We study five different configurations, in which the direction of the ram pressure on the gaseous disc varies from face-on to edge-on. Rotation curves (RCs) and 2D velocity fields of the gas are extracted from these simulations in a way that follows the procedure applied to observations of distant, small, and faint galaxies as closely as possible.Results. We find that the appearance of distortions of the gaseous disc due to ram-pressure stripping depends on the direction of the acting ram pressure. In the case of face-on ram pressure, the distortions mainly appear in the outer parts of the galaxy in a very symmetric way. This distinction between undisturbed inner part and symmetrically disturbed outer regions is visible in both the rotation curve and the 2D velocity field. In contrast, in the case of edge-on ram pressure we find stronger distortions. In particular, a mismatch between kinematic centre and the centre of the stellar disc becomes observable. In the RC, there are basically two features visible. The RC is asymmetric as the kinematic centre does not coincide with the optical centre of the galaxy. Secondly, the outer parts of the RC are declining. The 2D velocity field also shows signatures of the interaction in the inner part of the disc. At angles smaller than 45• between the ICM wind direction and the disc, the velocity field asymmetry increases significantly compared to larger angles. Compared to distortions caused by tidal interactions, the effects of ram-pressure stripping on the velocity field are relatively low in all cases and difficult to observe at intermediate redshift in seeing-limited observations.

Ram pressure and dusty red galaxies – key factors in the evolution of the multiple cluster system Abell 901/902

“…Since these rotation curves trace the gaseous disk of a galaxy, asymmetries in such a curve can be a measure for kinematic distortions due to environmental effects like ram-pressure stripping, mergers, galaxy harassment or tidal interactions with the cluster potential. Kronberger et al (2008) find in combined N-body/hydrodynamic simulations that the collision-less stellar disk is not affected by ram pressure and only the gaseous component shows disturbed kinematics. Asymmetries in the gas kinematics combined with a lack of distortions in the stellar disk could therefore be a strong indicator for ram-pressure stripping.…”

“…But also the influence of "nurture" can be important. Both Galaxy-galaxy interactions, such as tidal interactions, major/minor mergers, or harassment (Moore et al 1996), and galaxy-cluster interactions, such as ram-pressure stripping (Gunn & Gott 1972;Kronberger et al 2008) due to the ICM (Intra-cluster medium), halo truncation (Balogh et al 2000;Bekki et al 2001), or gas compression (Tonnesen & Bryan 2009;Byrd & Valtonen 1990) can play crucial roles in the evolution of galaxies. To decouple the different effects of environment on galaxy evolution, it is necessary to analyse a variety of galaxy properties, such as kinematics, spectral energy distributions (SEDs), morphologies, stellar masses, or star-formation rates (SFRs) over a wide range of environments.…”

Kinematic alignment of non-interacting CALIFA galaxies

“…However, several physical processes can disturb this regular behaviour. On the one hand, kinematic perturbations can be induced by external factors, such as ram-pressure stripping (e.g., Kronberger et al 2008) or galactic mergers (e.g., Naab & Burkert 2003). On the other hand, kinematic departures from regular rotation can be due to internal instabilities, such as spiral arms or bars (Binney & Tremaine 2008;Sellwood 2013).…”

Aperture corrections for disk galaxy properties derived from the CALIFA survey

“…Consequently, a fraction of the total flux at all wavelengths is lost and, to date, no recipe to correct for this effect has proved satisfactory, although several studies of aperture effects have been carried out (e.g. Brinchmann et al 2004;Ellis et al 2005;Kewley et al 2005;Salim et al 2007;Kronberger et al 2008;Gerssen et al 2012;Zahid et al 2013;Hopkins et al 2013).…”