An Observational Limit on the Dwarf Galaxy Population of the Local Group

Whiting, Alan B.; Hau, G. K. T.; Irwin, M. J.; Verdugo, M.

doi:10.1086/510309

Cited by 53 publications

(52 citation statements)

References 43 publications

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“…We choose this limit because there is widespread consensus that surveys of the surroundings of the MW and M31 are complete down to that limit (see e.g. Whiting et al 2007;McConnachie et al 2009;McConnachie 2012). We compare in the top panel of Fig.…”

Section: Number Of Bright Satellitesmentioning

confidence: 99%

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

Fattahi

Navarro

Sawala

et al. 2016

Mon. Not. R. Astron. Soc.

221

268

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We use a large sample of isolated dark matter halo pairs drawn from cosmological N-body simulations to identify candidate systems whose kinematics match that of the Local Group of Galaxies (LG). We find, in agreement with the "timing argument" and earlier work, that the separation and approach velocity of the Milky Way (MW) and Andromeda (M31) galaxies favour a total mass for the pair of ∼ 5 × 10 12 M ⊙ . A mass this large, however, is difficult to reconcile with the small relative tangential velocity of the pair, as well as with the small deceleration from the Hubble flow observed for the most distant LG members. Halo pairs that match these three criteria have average masses a factor of ∼ 2 times smaller than suggested by the timing argument, but with large dispersion, spanning more than a decade in mass. Guided by these results, we have selected 12 halo pairs with total mass in the range 1.6-3.6 × 10 12 M ⊙ for the APOSTLE project (A Project Of Simulations of The Local Environment), a suite of resimulations at various numerical resolution levels (reaching up to ∼ 10 4 M ⊙ per gas particle) that use the hydrodynamical code and subgrid physics developed for the EA-GLE project. These simulations reproduce, by construction, the main kinematics of the MW-M31 pair, and produce satellite populations whose overall number, luminosities, and kinematics are in good agreement with observations of the MW and M31 companions. These diagnostics are sensitive to the total mass assumed for the MW-M31 pair; indeed, the LG satellite population would be quite difficult to reproduce for pair masses as high as indicated by the timing argument. The APOSTLE candidate systems thus provide an excellent testbed to confront directly many of the predictions of the ΛCDM cosmology with observations of our local Universe.

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Section: Number Of Bright Satellitesmentioning

confidence: 99%

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

Fattahi

Navarro

Sawala

et al. 2016

Mon. Not. R. Astron. Soc.

221

268

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“…The usual manner to cope with this is to find which of the eight pixels surrounding the nominal central pixel has the minimum value of A . In this work, we use the luminosity‐weighted centre of Antlia quoted by Whiting et al (2007). This should be accurate to within less than 0.1 arcmin (i.e.…”

Section: Morphology Of Antliamentioning

confidence: 99%

Antlia Dwarf Galaxy: distance, quantitative morphology and recent formation history via statistical field correction

Pimbblet

Couch

2011

Monthly Notices of the Royal Astronomical Society

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We apply a statistical field correction technique originally designed to determine membership of high redshift galaxy clusters to Hubble Space Telescope (HST) imaging of the Antlia Dwarf Galaxy; a galaxy at the very edge of the Local Group. Using the tip of the red giant branch standard candle method coupled with a simple Sobel edge detection filter we find a new distance to Antlia of 1.31 ± 0.03 Mpc. For the first time for a Local Group member, we compute the concentration, asymmetry and clumpiness quantitative morphology parameters for Antlia from the distribution of resolved stars in the HST/Advanced Camera for Surveys (ACS) field, corrected with a new method for contaminants and complement these parameters with the Gini coefficient (G) and the second‐order moment of the brightest 20 per cent of the flux (M20). We show that it is a classic dwarf elliptical (C = 2.0, A = 0.063, S = 0.077, G = 0.39 and M20=−1.17 in the F814W band), but has an appreciable blue stellar population at its core, confirming on‐going star formation. The values of asymmetry and clumpiness, as well as Gini and M20 are consistent with an undisturbed galaxy. Although our analysis suggests that Antlia may not be tidally influenced by NGC 3109, it does not necessarily preclude such interaction.

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“…In the present investigation all Shapley-Ames galaxies with > À27 were to assigned to clusters (C), groups (G), and the general field ( F) by inspection of the prints of the Palomar Sky Survey, using the criteria described in x 2. As Whiting et al (2007) have recently pointed out, ''the idea of a visual survey on photographic material appears almost quixotic.'' Nevertheless, this appears to be the most efficient way of assessing the environmental characteristics of nearby galaxies, such as those contained in the Shapley-Ames Catalog.…”

Section: Galaxy Morphology and Environmental Densitymentioning

confidence: 99%

Some Musings on Galaxy Morphology, Galactic Colors, and the Environments of Galaxies

Bergh¹

2007

Astron J

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Careful inspection of large-scale photographs of Shapley-Ames galaxies seems to show a smooth transition between the morphological characteristics of galaxies located on the narrow red and on the broad blue sequences in the galaxian color-magnitude diagram. In other words, there does not appear to be a dichotomy between blue and red galaxies. Both the colors and the morphologies of galaxies are found to correlate strongly with their environments. Red and early-type Shapley-Ames galaxies are dominant in clusters, whereas blue late-type star-forming objects dominate the general field. Interestingly, the colors and morphologies of galaxies in small groups resemble the field and differ from those in clusters. As noted by Baade, the presence of dust and star formation are very closely correlated, except in a few galaxies that probably had unusual evolutionary histories. Over the entire range from S0 to Sc there is no significant difference between the integrated colors of normal and barred objects, suggesting that the formation of a bar does not significantly affect the stellar evolutionary history of a galaxy.

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An Observational Limit on the Dwarf Galaxy Population of the Local Group

Cited by 53 publications

References 43 publications

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

Antlia Dwarf Galaxy: distance, quantitative morphology and recent formation history via statistical field correction

Some Musings on Galaxy Morphology, Galactic Colors, and the Environments of Galaxies

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