Gas Loss by Ram Pressure Stripping and Internal Feedback From Low-Mass Milky Way Satellites

Abstract

The evolution of dwarf satellites of the Milky Way is affected by the combination of ram pressure and tidal stripping, and internal feedback from massive stars. We investigate gas loss processes in the smallest satellites of the Milky Way using three-dimensional, high resolution, idealized wind tunnel simulations, accounting for gas loss through both ram pressure stripping and expulsion by supernova feedback. Using initial conditions appropriate for a dwarf galaxy like Leo T, we investigate whether or not environmental gas stripping and internal feedback can quench these low mass galaxies on the expected timescales, shorter than 2 Gyr. We find that supernova feedback contributes negligibly to the stripping rate for these low star formation rate galaxies. However, we also find that ram pressure stripping is less efficient than expected in the stripping scenarios we consider. Our work suggests that, although ram pressure stripping can eventually completely strip these galaxies, other physics is likely at play to reconcile our computed stripping times with the rapid quenching timescales deduced from observations of low mass Milky Way dwarf galaxies. We discuss the roles additional physics may play in this scenario, including host-satellite tidal interactions, cored vs. cuspy dark matter profiles, reionization, and satellite pre-processing. We conclude that a proper accounting of these physics together is necessary to understand the quenching of low mass Milky Way satellites.

Under pressure: quenching star formation in low-mass satellite galaxies via stripping

“…Within the Local Group, modeling of the orbit and star-formation history of Leo I suggest that it experienced a small burst of star formation at pericentric passage prior to being quenched, consistent with being initiated by ram pressure Boylan-Kolchin et al 2013;Weisz et al 2014). This increase in star formation, driven by interaction with the host CGM, can inject energy into the ISM of the satellite, puffing up the system and thereby making it more susceptible to stripping (Stinson et al 2007;El-Badry et al 2016, but see also Emerick et al 2016). High-resolution hydrodynamic simulations of Milky Way-or Local Group-like environments should provide a robust means for studying the possible importance of feedback in increasing the efficiency of stripping (e.g.…”

Galaxy Zoo: the interplay of quenching mechanisms in the group environment★

“…However, there has been mounting evidence that RPS can only strip a galaxy of 40−60% of its gas supply (Fillingham et al 2016) and so may not be as effective a quenching mechanism as first thought (Emerick et al 2016). Therefore investigations of other environmentally driven quenching mechanisms, such as strangulation (Peng et al 2015;Hahn et al 2016;Maier et al 2016;Paccagnella et al 2016;Roberts et al 2016;van de Voort et al 2016) and harassment (high speed galaxy 'fly-by' gravitational interactions Bialas et al 2015;Smith et al 2015) are having a recent resurgence.…”

“…Although these correlations were originally interpreted as indicating causation, recent evidence from simulations suggests that quenching mechanisms driven by the environment may not be dominant in the galaxy lifecycle (Kimm et al 2009(Kimm et al , 2011Hirschmann et al 2014;Wang et al 2014;Phillips et al 2015;Emerick et al 2016;Fillingham et al 2016). Perhaps, instead, the correlation of increased quenched galaxy fractions with environment density is due to a superposition of other possible quenching mechanisms each of which depend on more local factors Blanton et al 2006;Cucciati et al 2010) than the broader environment properties Porter et al 2008;Fadda et al 2008;Darvish et al 2014Darvish et al , 2017Alpaslan et al 2016;Laigle et al 2017).…”

An Introduction to Gas Accretion onto Galaxies

“…It is difficult to say when the gas of Magellanic origin will accrete as it is likely to have a large tangential velocity component and will slow and be heated as it falls. An extended, diffuse halo medium is inferred to exist for the Milky Way from the nature of the Magellanic System and stripped satellites (Salem et al, 2015;Emerick et al, 2016;Grcevich & Putman, 2009). The motion of this diffuse halo medium is largely unknown, and much of it is thought to be hot and not easily observed.…”