Spiral instabilities provoked by accretion and star formation

Sellwood, J. A.; Carlberg, R. G.

doi:10.1086/162176

Cited by 421 publications

(459 citation statements)

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“…This trend is also followed by the other models with even lower accretion rates (0.9 and 1.8 M yr À1 ). These results confirm the early results by Sellwood & Carlberg (1984) and suggest that gas infall from halo regions, which is demonstrated by our simulations (in Figs. 1 and 2) to be greatly affected by the ICM, is a key parameter for morphological evolution of spirals.…”

Section: Morphological Evolution Of Spirals After Gas Strippingsupporting

confidence: 93%

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

Bekki

Couch

Shioya

2002

ApJ

332

384

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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.

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Section: Morphological Evolution Of Spirals After Gas Strippingsupporting

confidence: 93%

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

Bekki

Couch

Shioya

2002

ApJ

332

384

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“…A similar conclusion was also proposed by Dobbs & Bonnell (2008). They take a time-dependent gravitational potential from N -body simulations of Sellwood & Carlberg (1984), and run 3-D, two-phase (i.e. cold and warm) SPH simulations.…”

Section: Interplay Between Gas and Stellar Spiralssupporting

confidence: 68%

“…In other words, it is hard to produce 'steady' spirals that can be understood by Lin and Shu's density wave theory, in time-dependent simulations of collisionless disks. For example, Sellwood & Carlberg (1984), using 2D, particle-mesh simulations, pointed out that spirals become faint in about ten rotations (∼ a few Gyrs) †. In order to keep spirals for many rotations, they claimed that some mechanisms to reduce the velocity dispersion of stars are necessary.…”

Section: Evolution Of Pure Stellar Disksmentioning

confidence: 99%

Galactic scale star formation: Interplay between stellar spirals and the ISM

et al. 2010

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Abstract. Spiral structures in the disk galaxies have been extensively studied by many theoretical papers, but conventional steady-state models are not consistent with what we observe in time-dependent, multi-dimensional numerical simulations and also in real galaxies. Here we review recent progress in numerical modeling of stellar and gas spirals in disk galaxies. The spiral arms excited in a stellar disk can last for 10 Gyrs without the ISM, but each spiral arm is short-lived and is recurrently formed. The stellar spirals are not waves propagating with a single pattern speed. The ISM is concentrated in local potential minima, which roughly follow the galactic rotation together with the stellar arms, therefore galactic dust lanes are not the classic 'galactic shocks'.

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“…Recurrent spiral instabilities have been reported by Sellwood & Carlberg (1984) and Sellwood & Lin (1989) in their simulations of self gravitating discs. It was argued by Toomre & Kalnajs (1991) that these transient spiral density waves are due to the swing-amplification mechanism as first formulated by Toomre (1981).…”

Section: Spiral Structure Longevitymentioning

confidence: 83%

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Minchev

Famaey

Quillen

et al. 2012

A&A

186

208

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We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scalelengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surfacebrightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M /yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s −1 at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.

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Spiral instabilities provoked by accretion and star formation

Cited by 421 publications

References 0 publications

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

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

Galactic scale star formation: Interplay between stellar spirals and the ISM

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

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