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

Higgs, Clare; McConnachie, Alan W.; Irwin, M. J.; Bate, N. F.; Lewis, Geraint F.; Walker, Matthew G.; Côté, Patrick; Venn, Kim A.; Battaglia, G.

doi:10.1093/mnras/stw257

Cited by 31 publications

(45 citation statements)

References 117 publications

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“…We have checked the literature for evidence of an extended halo in these galaxies but we did not find any paper showing its existence. The only exception is SagDIG, for which we have found a published radial profile (Higgs et al 2016), but it did not show evidence for two stellar components (galaxy and halo) and the galaxy showed a possible signature of tidal stripping.…”

Section: Summary and Discussionmentioning

confidence: 72%

Ghostly haloes in dwarf galaxies: constraints on the star formation efficiency before reionization

Kang

Ricotti

2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT Stellar haloes observed around normal galaxies are extended and faint stellar structures formed by debris of tidally disrupted dwarf galaxies accreted overtime by the host galaxy. Around dwarf galaxies, these stellar haloes may not exist if all the accreted satellites are dark haloes without stars. However, if a stellar halo is found in sufficiently small mass dwarfs, the whole stellar halo is composed of tidal debris of fossil galaxies, and we refer to it as ghostly halo. Fossil galaxies are so called because they formed most of their stars before the epoch of reionization, and have been identified as the ultrafaint dwarf galaxies found around the Milky Way and M31. In this paper, we carry out semi-analytical simulations to characterize the sizes and stellar masses of ghostly stellar haloes in dwarf galaxies as a function of their dark matter halo mass. By comparing the models to observations of six isolated dwarf galaxies in the Local Group showing evidence of extended stellar haloes, we are able to constrain the star formation efficiency in fossil galaxies. We find that at redshift z ∼ 6, dark matter haloes in the mass range 107–109 M⊙ have a mean star formation efficiency $f_* \equiv M_*/M_{\mathrm{ dm}} \sim 0.1\!-\!0.2\hbox{ per cent}$ nearly constant as a function of the dark matter halo mass.

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Section: Summary and Discussionmentioning

confidence: 72%

Ghostly haloes in dwarf galaxies: constraints on the star formation efficiency before reionization

Kang

Ricotti

2019

Monthly Notices of the Royal Astronomical Society

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“…Making specific predictions will help ensure that the most promising targets are observed to avoid spending significant amounts of telescope time on many (potentially unnecessary) pointings to cover the full virial volume of a given field galaxy. We explicitly calculate expected numbers for galaxies included in the Solo dwarf survey Higgs et al (2016), which has recently observed all isolated dwarf field galaxies within 3 Mpc of the MW. For instance, a single pointing at IC 4662 with their 1 • × 1 • camera would cover a volume that encompasses a mean of ∼ 0.9 − 1.2 satellites with M * > 10 4 M according to the Moster, GK16, and GK14 models.…”

Section: Discussionmentioning

confidence: 99%

“…We apply the same calculations to all of the galaxies in Table 3 using an approximate field of view from the Solo dwarf survey. Solo has a 1 • × 1 • camera (Higgs et al 2016), which we approximate as a circular aperture with radius 0.56 • . We present all of the values expected for Solo in thē N fov column.…”

Section: Survey Strategy: Dependence On Field Of Viewmentioning

confidence: 99%

“…We focus specifically on the satellite systems of Local Group field dwarf galaxies, because the proximity of these galaxies enables the discovery of very low luminosity satellites as overdensities of resolved stars. We include specific predictions for the fields of view of the Solitary Local dwarfs survey (Solo), a recent survey of all isolated dwarfs within 3 Mpc of the Milky Way (Higgs et al 2016). Though the main goals of the Solo survey do not include finding satellites, it likely already has at least one lurking in its data.…”

Section: Introductionmentioning

confidence: 99%

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An observer's guide to the (Local Group) dwarf galaxies: predictions for their own dwarf satellite populations

Dooley

Peter

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

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A recent surge in the discovery of new ultrafaint dwarf satellites of the Milky Way has inspired the idea of searching for faint satellites, 10 3 M < M * < 10 6 M , around less massive field galaxies in the Local Group. Such satellites would be subject to weaker environmental influences than Milky Way satellites, and could lead to new insights on low mass galaxy formation. In this paper, we predict the number of luminous satellites expected around field dwarf galaxies by applying several abundance matching models and a reionization model to the dark-matter only Caterpillar simulation suite. For three of the four abundance matching models used, we find a > 99% chance that at least one satellite with stellar mass M * > 10 5 M exists around the combined five Local Group field dwarf galaxies with the largest stellar mass. When considering satellites with M * > 10 4 M , we predict a combined 5 − 25 satellites for the five largest field dwarfs, and 10 − 50 for the whole Local Group field dwarf population. Because of the relatively small number of predicted dwarfs, and their extended spatial distribution, a large fraction each Local Group dwarf's virial volume will need to be surveyed to guarantee discoveries. We compute the predicted number of satellites in a given field of view of specific Local Group galaxies, as a function of minimum satellite luminosity, and explicitly obtain such values for the Solitary Local dwarfs survey. Uncertainties in abundance matching and reionization models are large, implying that comprehensive searches could lead to refinements of both models.

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“…UGC 4879 is presented here as one example of the Solo dwarfs. The basic analysis techniques are detailed in Higgs et al (2016). Fig.…”

Section: Example Galaxy: Ugc 4879mentioning

confidence: 99%

Isolated dwarf galaxies in the Local Group

Higgs¹,

McConnachie²

2018

Proc. IAU

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The Solo (Solitary local) Dwarf Galaxy Survey is a volume limited sample of all nearby (< 3 Mpc) and isolated (> 300 kpc from the Milky Way or M31) dwarfs, with wide-field g and i imaging. This survey uses resolved stellar populations to parameterize these low mass systems. Comparison to the well studied satellite dwarfs characterizes the evolutionary impact of a large galaxy in close proximity. The deep, wide field nature of this survey also lends itself to searching for nearby substructures, both globular clusters and possible faint satellites.Current work is focused on the 16 closest Solo dwarfs, all within the virial radius (approximately 1 Mpc) of the Local Group. This subset has been characterized using consistent methods, despite their diversity in stellar mass and apparent size. The analysis highlights the extended stellar structure and morphology. We will examine trends with star formation history, and separation from a large host. This first subset emphasizes the survey’s unique challenges and advantages.The Solo Survey provides detailed look at the extended structure of dwarfs and characterizes the evolution of galaxies in the faint limit.

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

Cited by 31 publications

References 117 publications

Ghostly haloes in dwarf galaxies: constraints on the star formation efficiency before reionization

Ghostly haloes in dwarf galaxies: constraints on the star formation efficiency before reionization

An observer's guide to the (Local Group) dwarf galaxies: predictions for their own dwarf satellite populations

Isolated dwarf galaxies in the Local Group

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