Thin discs, thick dwarfs and the effects of stellar feedback

Sánchéz-Janssen, R.; Méndez-Abreu, J.; Aguerri, J. A. L.

doi:10.1111/j.1745-3933.2010.00883.x

Cited by 115 publications

(96 citation statements)

References 48 publications

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“…This is in concordance with observations (Yoachim & Dalcanton 2006;Sánchez-Janssen et al 2010) and also expected since gas cooling is less efficient in smaller halos (Kaufmann et al 2007;Robertson & Kravtsov 2008). We explore two different scale lengths of the gaseous disk in comparison to the stellar disk, namely R g = R d , and R g = 2R d .…”

Section: Main (Disky Dwarf) Galaxiessupporting

confidence: 72%

Dark influences

Starkenburg

Helmi

Sales

2016

A&A

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Context. It has been proposed that mergers induce starbursts and lead to important morphological changes in galaxies. Most studies so far have focused on large galaxies, but dwarfs might also experience such events, since the halo mass function is scale-free in the concordance cosmological model. Notably, because of their low mass, most of their interactions will be with dark satellites. Aims. In this paper we follow the evolution of gas-rich disky dwarf galaxies as they experience a minor merger with a dark satellite. We aim to characterize the effects of such an interaction on the dwarf's star formation, morphology, and kinematical properties. Methods. We performed a suite of carefully set-up hydrodynamical simulations of dwarf galaxies that include dark matter, gas, and stars merging with a satellite consisting solely of dark matter. For the host system we vary the gas fraction, disk size and thickness, halo mass, and concentration, while we explore different masses, concentrations, and orbits for the satellite. Results. We find that the interactions cause strong starbursts of both short and long duration in the dwarfs. Their star formation rates increase by factors of a few to 10 or more. They are strongest for systems with extended gas disks and high gas fractions merging with a high-concentration satellite on a planar, radial orbit. In contrast to analogous simulations of Milky Way-mass galaxies, many of the systems experience strong morphological changes and become spheroidal even in the presence of significant amounts of gas. Conclusions. The simulated systems compare remarkably well with the observational properties of a large selection of irregular dwarf galaxies and blue compact dwarfs. This implies that mergers with dark satellites might well be happening but not be fully evident, and may thus play a role in the diversity of the dwarf galaxy population.

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Section: Main (Disky Dwarf) Galaxiessupporting

confidence: 72%

Dark influences

Starkenburg

Helmi

Sales

2016

A&A

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“…Under the assumption of an inclined disk, we can use the shape of the observed distribution of RGB stars to constrain the possible inclination angle of Sag DIG. As a low mass system, several observational studies have shown that we do not expect the stars to be in a thin disk akin to large galaxies (see Roychowdhury et al 2010;Sánchez-Janssen et al 2010). From a theoretical perspective, we expect pressure support to be more important in low mass dark matter halos, leading to puffier disks (Kaufmann et al 2007).…”

Section: On the Content And Structure Of Sag Digmentioning

confidence: 99%

Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

Higgs¹,

McConnachie²,

Irwin³

et al. 2016

Mon. Not. R. Astron. Soc.

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We introduce the Solitary Local Dwarfs Survey (Solo), a wide field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multi-band imaging from CFHT/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than M V −18 situated beyond the nominal virial radius of the Milky Way and M31 ( 300 kpc) are included in this volume-limited sample, for a total of 42 targets. In addition to reviewing the survey goals and strategy, we present results for the Sagittarius Dwarf Irregular Galaxy (Sag DIG), one of the most isolated, low mass galaxies, located at the edge of the Local Group. We analyze its resolved stellar populations and their spatial distributions. We provide updated estimates of its central surface brightness and integrated luminosity, and trace its surface brightness profile to a level fainter than 30 mag./sq.arcsec. Sag DIG is well described by a highly elliptical (disk-like) system following a single component Sersic model. However, a low-level distortion is present at the outer edges of the galaxy that, were Sag DIG not so isolated, would likely be attributed to some kind of previous tidal interaction. Further, we find evidence of an extremely low level, extended distribution of stars beyond ∼ 5 arcmins (> 1.5 kpc) that suggests Sag DIG may be embedded in a very low density stellar halo. We compare the stellar and HI structures of Sag DIG, and discuss results for this galaxy in relation to other isolated, dwarf irregular galaxies in the Local Group.

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“…Mastropietro et al 2005;Smith et al 2010;Bialas et al 2015). The cool, thin disks of previous studies are often so thin that they have no known observable counterpart (Sánchez-Janssen et al 2010). Harassment simulations that start with cool, thin dwarf disks demonstrate that to convert the thin disks into thick disks requires sufficent tidal heating that there is additional tidal stripping of the stars (e.g.…”

Section: The Stellar Distributionmentioning

confidence: 99%

The sensitivity of harassment to orbit: mass loss from early-type dwarfs in galaxy clusters

Smith

Sánchéz-Janssen

Beasley

et al. 2015

Mon. Not. R. Astron. Soc.

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119

125

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We conduct a comprehensive numerical study of the orbital dependence of harassment on early-type dwarfs consisting of 168 different orbits within a realistic, Virgo-like cluster, varying in eccentricity and pericentre distance. We find harassment is only effective at stripping stars or truncating their stellar disks for orbits that enter deep into the cluster core. Comparing to the orbital distribution in cosmological simulations, we find that the majority of the orbits (more than three quarters) result in no stellar mass loss. We also study the effects on the radial profiles of the globular cluster systems of early-type dwarfs. We find these are significantly altered only if harassment is very strong. This suggests that perhaps most early-type dwarfs in clusters such as Virgo have not suffered any tidal stripping of stars or globular clusters due to harassment, as these components are safely embedded deep within their dark matter halo. We demonstrate that this result is actually consistent with an earlier study of harassment of dwarf galaxies, despite the apparent contradiction. Those few dwarf models that do suffer stellar stripping are found out to the virial radius of the cluster at redshift=0, which mixes them in with less strongly harassed galaxies. However when placed on phase-space diagrams, strongly harassed galaxies are found offset to lower velocities compared to weakly harassed galaxies. This remains true in a cosmological simulation, even when halos have a wide range of masses and concentrations. Thus phase-space diagrams may be a useful tool for determining the relative likelihood that galaxies have been strongly or weakly harassed.

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Thin discs, thick dwarfs and the effects of stellar feedback

Cited by 115 publications

References 48 publications

Dark influences

Dark influences

Solo dwarfs I: survey introduction and first results for the Sagittarius dwarf irregular galaxy

The sensitivity of harassment to orbit: mass loss from early-type dwarfs in galaxy clusters

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