SPECTROSCOPIC CONFIRMATION OF THE DWARF SPHEROIDAL GALAXY d0994+71 AS A MEMBER OF THE M81 GROUP OF GALAXIES

Toloba, Elisa; Sand, David J.; Guhathakurta, Puragra; Chiboucas, Kristin; Crnojević, Denija; Simon, Joshua D.

doi:10.3847/2041-8205/830/1/l21

Cited by 10 publications

(12 citation statements)

References 45 publications

(65 reference statements)

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“…Many objects of similarly low surface brightness are found in our general CFHTLS search, and we expect to fill in this surface brightness range in future work. We also plot the two UDGs in the Local Universe that also show signs of interaction -Scl-MM-Dw2 Toloba et al (2016) and CenA-MM-Dw3 (Crnojević et al 2016).…”

Section: Structure and Luminositymentioning

confidence: 99%

Evidence for Ultra-diffuse Galaxy “Formation” through Galaxy Interactions

Bennet

Sand

Zaritsky

et al. 2018

ApJL

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We report the discovery of two ultra-diffuse galaxies (UDGs) which show clear evidence for association with tidal material and interaction with a larger galaxy halo, found during a search of the Wide portion of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The two new UDGs, NGC2708-Dw1 and NGC5631-Dw1, are faint (M g =−13.7 and −11.8 mag), extended (r h =2.60 and 2.15 kpc) and have low central surface brightness (µ(g, 0)=24.9 and 27.3 mag arcsec −2 ), while the stellar stream associated with each has a surface brightness µ(g) 28.2 mag arcsec −2 . These observations provide evidence that the origin of some UDGs may connect to galaxy interactions, either by transforming normal dwarf galaxies by expanding them, or because UDGs can collapse out of tidal material (i.e. they are tidal dwarf galaxies). Further work is needed to understand the fraction of the UDG population 'formed' through galaxy interactions, and wide field searches for diffuse dwarf galaxies will provide further clues to the origin of these enigmatic stellar systems.

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Section: Structure and Luminositymentioning

confidence: 99%

Evidence for Ultra-diffuse Galaxy “Formation” through Galaxy Interactions

Bennet

Sand

Zaritsky

et al. 2018

ApJL

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“…Recent success in the determination of both stellar halo density profiles (e.g., Merritt et al 2016;Harmsen et al 2016) and satellite populations (Crnojević et al 2016;Toloba et al 2016) of nearby galaxies will soon enable similar studies on a sample of external galaxies.…”

Section: The Mw's Likely Poor and Concentrated Ashmentioning

confidence: 99%

The accreted stellar halo as a window on halo assembly in L* galaxies

Amorisco

2017

Monthly Notices of the Royal Astronomical Society: Letters

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Theory and observations agree that the accreted stellar halos (ASHs) of Milky Way-like galaxies display significant scatter. I take advantage of this stochasticity to invert the link between halo assembly history (HAH) and ASH, using mock ASHs corresponding to 750 ΛCDM HAHs, sharing a final virial mass of M h (z = 0) = 10 12.25 M . Hosts with poor/rich ASHs assemble following orthogonal growth-patterns. Hosts with rich ASHs experience accretion events (AEs) with high virial mass ratios (HVMRs, M s /M h 0.1) at 0.5 z inf all 1.5, in a phase of fast growth. This maximizes the accreted stellar mass under the condition these satellites are disrupted by z = 0. At similar times, hosts with poor ASHs grow slowly through minor mergers, with only very recent HVMR AEs: this results in a globally more abundant satellite population and in distinctive surviving massive satellites (stellar mass log M s, * /M 9). Several properties of the Milky Way are in agreement with the predictions of this framework for hosts with poor, concentrated ASHs, including: i) the recent infall of Sagittarius and Magellanic Clouds, ii) the likely higher-than-average concentration of its dark halo, iii) the signatures of fast chemical enrichment of a sizable fraction of its halo stellar populations.

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“…To date, we have confirmed two new faint satellites around Sculptor (M V ∼ −10 and −12), of which one (Scl-MM-Dw2) is an intriguing tidally disrupting ultra-diffuse galaxy ( [12,13]; i.e., a galaxy with an effective radius larger than ∼1.5 kpc and a low central surface brightness, in this case µ V,0 ∼ 26 mag arcsec −2 , following the definition by [14]). We are following-up Scl-MM-Dw2 with a novel coadded stellar spectroscopy technique ( [15]) which will allow us to assess the possible presence of velocity and metallicity gradients along its extent; • satellites of Cen A: within the PISCeS footprint we have discovered nine new satellites of Cen A, with luminosities in the range M V ∼ −8/−14, as confirmed by our HST follow-up imaging (GO-13856 and GO-14259; see also [11]). Of particular interest are: CenA-MM-Dw3, a disrupting dwarf at ∼90 kpc from Cen A with extended tidal tails (∼2 deg), which has the faint surface brightness of an ultra-diffuse galaxy, a prominent nuclear star cluster and a strong metallicity gradient along its tails; and CenA-MM-Dw1, another ultra-diffuse dwarf with a fainter candidate satellite of its own and a globular cluster system similar to the one of the Fornax dwarf in the LG.…”

Section: Resultsmentioning

confidence: 99%

Resolving the Extended Stellar Halos of Nearby Galaxies: The Wide-Field PISCeS Survey

Crnojević

2017

Galaxies

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Abstract:The wide-field Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) investigates the resolved stellar halos of two nearby galaxies (the spiral NGC 253 and the elliptical Centaurus A, D ∼ 4 Mpc) out to a galactocentric radius of 150 kpc. The survey to date has led to the discovery of 11 confirmed faint satellites and stunning streams/substructures in two environments substantially different from the Local Group; i.e., the loose Sculptor group of galaxies and the Centaurus A group dominated by an elliptical. The newly discovered satellites and substructures, with surface brightness limits as low as ∼32 mag/arcsec 2 , are then followed-up with HST imaging and Keck/VLT spectroscopy to investigate their stellar populations. The PISCeS discoveries clearly testify the past and ongoing accretion processes shaping the halos of these nearby galaxies, and provide the first census of their satellite systems down to an unprecedented M V < −8. Keywords: galaxies: evolution; galaxies: groups; galaxies: halos; galaxies: photometry The Past, Present, and Future of Near-Field CosmologyThe past decade has seen a tremendous effort to study the properties of our Milky Way (MW) and its neighbouring Local Group (LG) galaxies in great detail. In particular, the wide-field surveys of the MW-analogue M31 (PAndAS, SPLASH; [1,2]) have highlighted significant differences in the halo properties, accretion history, and satellite populations of the two LG giant spirals. This is unsurprising, as theoretical simulations predict a large halo-to-halo scatter in the properties of MW-sized halos (e.g., [3]), but it certainly underlines the need for in-depth surveys of galaxies beyond the LG.A variety of approaches can be adopted to refine our knowledge of galaxy halos and their inhabitants: for example, deep pencil-beam surveys of a select sample of nearby (<10-15 Mpc) galaxies can be performed from the space (the Galaxy Halos, Outer disks, Substructure, Thick disks, and Star clusters, or GHOSTS, survey; e.g., [4]); or a larger number of more distant (>15-20 Mpc), unresolved galaxies can be investigated in integrated light (e.g., [5][6][7]). However, it remains an observational challenge to produce wide and deep resolved stellar maps such as those available for LG galaxies. With the advent of ground-based wide-field imagers, the first PAndAS-like maps for nearby MW-analogues are finally starting to be obtained (e.g., [8,9]). The PISCeS SurveyThe Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) was designed to help bridge the gap between our detailed knowledge of LG galaxies' properties and the integrated light information from unresolved galaxies at larger distances by targeting two resolved galaxies at ∼4 Mpc. To facilitate a comparison to the MW and M31, the PISCeS targets are ∼ MW-mass galaxies, a spiral (NGC 253, also known as Sculptor) and an elliptical (NGC 5128, or Centaurus A, Cen A). The former is part of a

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SPECTROSCOPIC CONFIRMATION OF THE DWARF SPHEROIDAL GALAXY d0994+71 AS A MEMBER OF THE M81 GROUP OF GALAXIES

Cited by 10 publications

References 45 publications

Evidence for Ultra-diffuse Galaxy “Formation” through Galaxy Interactions

Evidence for Ultra-diffuse Galaxy “Formation” through Galaxy Interactions

The accreted stellar halo as a window on halo assembly in L* galaxies

Resolving the Extended Stellar Halos of Nearby Galaxies: The Wide-Field PISCeS Survey

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