Passive Spiral Formation from Halo Gas Starvation: Gradual Transformation into S0s

Abstract

Recent spectroscopic and high-resolution Hubble Space Telescope (HST) imaging observations have revealed significant numbers of '' passive '' spiral galaxies in distant clusters, with all the morphological hallmarks of a spiral galaxy (in particular, spiral arm structure), but with weak or absent star formation. Exactly how such spiral galaxies formed and whether they are the progenitors of present-day S0 galaxies is unclear. Based on analytic arguments and numerical simulations of the hydrodynamical evolution of a spiral galaxy's halo gas (which is a likely candidate for the source of gas replenishment for star formation in spirals), we show that the origin of passive spirals may well be associated with halo gas stripping. Such stripping results mainly from the hydrodynamical interaction between the halo gas and the hot intracluster gas. Our numerical simulations demonstrate that even if a spiral orbits a cluster with a pericenter distance $3 times larger than the cluster core radius, $80% of the halo gas is stripped within a few Gyr and, accordingly, cannot be accreted by the spiral. Furthermore, our study demonstrates that this dramatic decline in the gaseous infall rate leads to a steady increase in the Q parameter for the disk, with the spiral arm structure, although persisting, becoming less pronounced as the star formation rate gradually decreases. These results suggest that passive spirals formed in this way gradually evolve into red cluster S0s.

The SAMI Galaxy Survey: spatially resolving the environmental quenching of star formation in GAMA galaxies

“…Some simulations (e.g. Bekki, Couch, & Shioya 2002) suggest that the formation of anaemic spirals, systems with uniformly suppressed star formation (van den Bergh 1991; Elmegreen et al 2002), can be explained by strangulation. This process is not expected to produce the same spatial distribution of star formation as other processes such as ram-pressure stripping while quenching is taking place.…”

Nature vs. nurture in the low-density environment: structure and evolution of early-type dwarf galaxies in poor groups

“…Low-mass galaxies are more susceptible to environmental effects owing to their shallow potential well that facilitates the removal of gas from the galaxies. Hydrodynamical simulations show that, while for massive galaxies ram-pressure stripping is only effective in the cores of rich clusters, dwarf galaxies can be completely stripped of their gas even in poor groups (e.g., Bekki et al 2001;Bekki et al 2002;Marcolini et al 2003). Suffocation, ram-pressure stripping, and galaxy harassment can deprive dwarf galaxies of their gas reservoir, quenching star formation and transforming them into passive dwarf ellipticals.…”

Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

“…In particular, those physical mechanisms related to the gas content of the galaxies can influence the morphology and the structural parameters of dwarf and bright galaxies. Thus, ram-pressure stripping (see Gunn & Gott 1972;Quilis et al 2000;Bekki 2009), strangulation (see Kawata & Mulchaey 2008), and starvation (see Larson et al 1980;Bekki et al 2002) produce the sweep of the cold and/or hot gas from the galaxies. This loss of gas stops the active star formation of the galaxies and produces a decrease in their stellar surface brightness (see e.g.…”

“…Several physical processes taking place in clusters can produce strong galaxy evolution (see Boselli & Gavazzi 2006) although some affect only the gas content of the galaxies. We may mention ram-pressure stripping (see Gunn & Gott 1972;Quilis et al 2000;Bekki 2009), starvation (see Larson et al 1980;Bekki et al 2002), and strangulation (see Kawata & Mulchaey 2008). Other processes affect both their gas and stellar contents; these include harassment (Moore et al 1996), tidal interactions (Merritt 1984;Aguerri & González-García 2009), and mergers.…”