A Trio of New Local Group Galaxies with Extreme Properties

McConnachie, Alan W.; Huxor, Avon; Martín, Nicolás F.; Irwin, M. J.; Chapman, Scott; Fahlman, Gregory G.; Ferguson, Annette M. N.; Ibata, Rodrigo; Lewis, Geraint F.; Richer, Harvey B.; Tanvir, Nial

doi:10.1086/591313

Cited by 148 publications

(187 citation statements)

References 77 publications

(94 reference statements)

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“…For M31, our knowledge of satellites is largely based on imaging surveys such as the Pan Andromeda Archeological Survey (PAndAS, McConnachie et al 2009, see also Ferguson et al 2002;Ibata et al 2007;McConnachie et al 2008). As shown by Brasseur et al (2011), PAndAS is complete down to our mass limit within a survey footprint that covers a radial distance of roughly 150 kpc surrounding M31.…”

Section: Local Group Satellitesmentioning

confidence: 99%

Taking care of business in a flash : constraining the time-scale for low-mass satellite quenching with ELVIS

Fillingham

Cooper

Wheeler

et al. 2015

Mon. Not. R. Astron. Soc.

133

190

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The vast majority of dwarf satellites orbiting the Milky Way and M31 are quenched, while comparable galaxies in the field are gas-rich and star-forming. Assuming that this dichotomy is driven by environmental quenching, we use the ELVIS suite of N -body simulations to constrain the characteristic timescale upon which satellites must quench following infall into the virial volumes of their hosts. The high satellite quenched fraction observed in the Local Group demands an extremely short quenching timescale (∼ 2 Gyr) for dwarf satellites in the mass range M ∼ 10 6 − 10 8 M . This quenching timescale is significantly shorter than that required to explain the quenched fraction of more massive satellites (∼ 8 Gyr), both in the Local Group and in more massive host halos, suggesting a dramatic change in the dominant satellite quenching mechanism at M 10 8 M . Combining our work with the results of complementary analyses in the literature, we conclude that the suppression of star formation in massive satellites (M ∼ 10 8 − 10 11 M ) is broadly consistent with being driven by starvation, such that the satellite quenching timescale corresponds to the cold gas depletion time. Below a critical stellar mass scale of ∼ 10 8 M , however, the required quenching times are much shorter than the expected cold gas depletion times. Instead, quenching must act on a timescale comparable to the dynamical time of the host halo. We posit that ram-pressure stripping can naturally explain this behavior, with the critical mass (of M ∼ 10 8 M ) corresponding to halos with gravitational restoring forces that are too weak to overcome the drag force encountered when moving through an extended, hot circumgalactic medium.

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Section: Local Group Satellitesmentioning

confidence: 99%

Taking care of business in a flash : constraining the time-scale for low-mass satellite quenching with ELVIS

Fillingham

Cooper

Wheeler

et al. 2015

Mon. Not. R. Astron. Soc.

133

190

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“…SDSS, Hα by Devereux et al 1994; or the PAndAS survey, see e.g. McConnachie et al 2008), near and far-infrared (FIR) (Haas et al 1998;Barmby et al 2006;Gordon et al 2006;Beaton et al 2007;Krause et al, in prep. ), millimeter (Nieten et al 2006) and radio (e.g.…”

Section: Introduction An Overall View Of the Interstellar Medium Of Tmentioning

confidence: 99%

TheHerschelExploitation of Local Galaxy Andromeda (HELGA)

Fritz

Gentile

Smith

et al. 2012

A&A

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Context. We have obtained Herschel images at five wavelengths from 100 to 500 μm of a ∼5.5 × 2.5 degree area centred on the local galaxy M 31 (Andromeda), our nearest neighbour spiral galaxy, as part of the Herschel guaranteed time project "HELGA". The main goals of HELGA are to study the characteristics of the extended dust emission, focusing on larger scales than studied in previous observations of Andromeda at an increased spatial resolution, and the obscured star formation. Aims. In this paper we present data reduction and Herschel maps, and provide a description of the far-infrared morphology, comparing it with features seen at other wavelengths. Methods. We used high-resolution maps of the atomic hydrogen, fully covering our fields, to identify dust emission features that can be associated to M 31 with confidence, distinguishing them from emission coming from the foreground Galactic cirrus. Results. Thanks to the very large extension of our maps we detect, for the first time at far-infrared wavelengths, three arc-like structures extending out to ∼21, ∼26 and ∼31 kpc respectively, in the south-western part of M 31. The presence of these features, hosting ∼2.2 × 10 6 M of dust, is safely confirmed by their detection in HI maps. Overall, we estimate a total dust mass of ∼5.8 × 10 7 M , about 78% of which is contained in the two main ring-like structures at 10 and 15 kpc, at an average temperature of 16.5 K. We find that the gas-to-dust ratio declines exponentially as a function of the galacto-centric distance, in agreement with the known metallicity gradient, with values ranging from 66 in the nucleus to ∼275 in the outermost region. Conclusions. Dust in M 31 extends significantly beyond its optical radius (∼21 kpc) and what was previously mapped in the farinfrared. An annular-like segment, located approximately at R 25 , is clearly detected on both sides of the galaxy, and two other similar annular structures are undoubtedly detected on the south-west side even further out.

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“…These systems range from relatively luminous dwarf spheroidal (dSph) galaxies towards ever fainter objects, commonly dubbed ultrafaint dwarfs (UFDs; e.g., [2][3][4][5][6]; see also [7], and references therein). At 10 3 -10 5 M , the stellar masses of the UFDs are comparable to the most extended MW star clusters.…”

Section: Introductionmentioning

confidence: 99%

The puzzling assembly of the Milky Way halo – contributions from dwarf Spheroidals and globular clusters

Koch

Lépine

Çalışkan

2012

EPJ Web of Conferences

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Abstract. While recent sky surveys have uncovered large numbers of ever fainter Milky Way satellites, their classification as star clusters, low-luminosity galaxies, or tidal overdensities remains often unclear. Likewise, their contributions to the build-up of the halo is yet debated. In this contribution we will discuss the current knowledge of the stellar populations and chemo-dynamics in these puzzling satellites, with a particular focus on dwarf spheroidal galaxies and the globular clusters in the outer Galactic halo. Also the question of whether some of the outermost halo objects are dynamically associated with the (Milky Way) halo at all is addressed in terms of proper measurements in the remote Leo I and II dwarf galaxies.

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A Trio of New Local Group Galaxies with Extreme Properties

Cited by 148 publications

References 77 publications

Taking care of business in a flash : constraining the time-scale for low-mass satellite quenching with ELVIS

Taking care of business in a flash : constraining the time-scale for low-mass satellite quenching with ELVIS

TheHerschelExploitation of Local Galaxy Andromeda (HELGA)

The puzzling assembly of the Milky Way halo – contributions from dwarf Spheroidals and globular clusters

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