The Various Kinematics of Dwarf Irregular Galaxies in Nearby Groups and Their Dark Matter Distributions

Côté, Stéphanie; Carignan, C.; Freeman, K. C.

doi:10.1086/316883

Cited by 182 publications

(255 citation statements)

References 73 publications

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“…Similar conclusions have also been made from observations of high surface brightness disc galaxies (Salucci 2001). At small radii (typically a few kpcs), the mass distribution can better be described by a central, constant-density core (e.g., Flores & Primack 1994;Côté et al 2000;Marchesini et al 2002;Gentile et al 2004). …”

Section: Introductionsupporting

confidence: 77%

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

Eymeren

Trachternach

Koribalski

et al. 2009

A&A

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Context. The cusp-core discrepancy is one of the major problems in astrophysics. It results from comparing the observed mass distribution of galaxies with the predictions of cold dark matter simulations. The latter predict a cuspy density profile in the inner parts of galaxies, whereas observations of dwarf and low surface brightness galaxies show a constant-density core. Aims. We want to determine the shape of the dark matter potential in the nuclear regions of a sample of six nearby irregular dwarf galaxies. Methods. In order to quantify the amount of non-circular motions that could potentially affect a mass decomposition, we first perform a harmonic decomposition of the H i Hermite velocity fields of all sample galaxies. We then decompose the H i rotation curves into different mass components by fitting NFW and pseudo-isothermal halo models to the H i rotation curves using a χ 2 minimisation. We model the minimum-disc, the minimum-disc + gas, and the maximum-disc cases.Results. The non-circular motions are in all cases studied here of the order of only a few km s −1 (generally corresponding to less than 25% of the local rotation velocity), which means that they do not significantly affect the rotation curves. The observed rotation curves can better be described by the cored pseudo-isothermal halo than by the NFW halo. The slopes of the dark matter density profiles confirm this result and are in good agreement with previous studies. The quality of the fits can often be improved when including baryons, which suggests that they contribute significantly to the inner part of the density profile of dwarf galaxies.

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Section: Introductionsupporting

confidence: 77%

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

Eymeren

Trachternach

Koribalski

et al. 2009

A&A

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“…The largest members are generally early-type galaxies. A large number of dwarf galaxies is however known (Côté et al 1997;Côté et al 2000;Banks et al 1999), making this group ideal for this kind of survey, due to its small distance as well as large over density.…”

Section: Targetsmentioning

confidence: 99%

An $\ion{H}{i}$ survey of the Centaurus and Sculptor groups

Blok¹,

Dijkstra²,

Briggs³

et al. 2002

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Abstract. We present results of two 21-cm H i surveys performed with the Australia Telescope Compact Array in the nearby Centaurus A and Sculptor galaxy groups. These surveys are sensitive to compact H i clouds and galaxies with H i masses as low as ∼3 × 10 6 M , and are therefore among the most sensitive extragalactic H i surveys to date. The surveys consist of sparsely spaced pointings that sample approximately 2% of the groups' area on the sky. We detected previously known group members, but we found no new H i clouds or galaxies down to the sensitivity limit of the surveys. If the H i mass function had a faint end slope of α = 1.5 below MH i = 10 7.5 M in these groups, we would have expected ∼3 new objects. Cold dark matter theories of galaxy formation predict the existence of a large number low mass dark matter sub-halos that might appear as tiny satellites in galaxy groups. Our results support and extend similar conclusions derived from previous H i surveys that a H i rich population of these satellites does not exist.

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“…Karachentsev et al 2007). The search for and study of dwarf members in this group have been pursued at different wavelengths for more than a decade (Côté et al 1997;Karachentseva & Karachentsev 1998;Banks et al 1999;Côté et al 2000;Jerjen et al 2000a,b;Karachentsev et al 2002Karachentsev et al , 2004Karachentsev 2005;Rejkuba et al 2006;Bouchard et al 2007;Grossi et al 2007;Karachentsev et al 2007;Lee et al 2007;Bouchard et al 2009;Côté et al 2009). Now there are more than 50 confirmed dwarf galaxies known in the Centaurus A group, of which about 3/5 are early-type dwarfs.…”

Section: Introductionmentioning

confidence: 99%

A close look at the Centaurus A group of galaxies

Crnojević¹,

Grebel²,

Koch³

2010

A&A

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Aims. We study dwarf galaxies in the Centaurus A group to investigate their metallicity and possible environmental effects. The Centaurus A group (at ∼4 Mpc from the Milky Way) contains about 50 known dwarf companions of different morphologies and stellar contents, thus making it a very interesting target to study how these galaxies evolve. Methods. Here we present results for the early-type dwarf galaxy population in this group. We used archival HST/ACS data to study the resolved stellar content of 6 galaxies, together with isochrones from the Dartmouth stellar evolutionary models. Results. We derive photometric metallicity distribution functions of stars on the upper red giant branch via isochrone interpolation. The 6 galaxies are moderately metal-poor ( [Fe/H] = −1.56 to −1.08), and metallicity spreads are observed (internal dispersions of σ[Fe/H] = 0.10−0.41 dex). We also investigate whether intermediate-age stars are present, and discuss how these affect our results. The dwarfs exhibit flat to weak radial metallicity gradients. For the two most luminous, most metal-rich galaxies, we find statistically significant evidence of at least two stellar subpopulations: the more metal-rich stars are found in the center of the galaxies, while the metal-poor ones are more broadly distributed within the galaxies. Conclusions. We find no clear trend in the derived physical properties as a function of (present-day) galaxy position in the group, which may come from the small sample we investigate. We compare our results to the early-type dwarf population of the Local Group, and find no outstanding differences, even though the Centaurus A group is a denser environment that is possibly in a more advanced dynamical stage.

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The Various Kinematics of Dwarf Irregular Galaxies in Nearby Groups and Their Dark Matter Distributions

Cited by 182 publications

References 73 publications

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

Non-circular motions and the cusp-core discrepancy in dwarf galaxies

An $\ion{H}{i}$ survey of the Centaurus and Sculptor groups

A close look at the Centaurus A group of galaxies

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