Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions

Belokurov, V.; Zucker, D. B.; Evans, N. W.; Kleyna, Jan; Koposov, S. E.; Hodgkin, S. T.; Irwin, M. J.; Gilmore, G.; Wilkinson, M. I.; Fellhauer, M.; Bramich, D. M.; Hewett, Paul C.; Vidrih, S.; Jong, J. T. A. de; Smith, J. Allyn; Rix, H. W.; Bell, Eric F.; Wyse, Rosemary F. Ġ.; Newberg, Heidi Jo; Mayeur, P. A.; Yanny, B.; Rockosi, Constance M.; Gnedin, Oleg Y.; Schneider, D.; Beers, Timothy C.; Barentine, John C.; Brewington, H.; Brinkmann, Jonathan; Harvanek, Michael; Kleinman, S. J.; Krzesiński, Jurek; Long, Daniel C.; Nitta, A.; Snedden, Stephanie A.

doi:10.1086/509718

Cited by 687 publications

(626 citation statements)

References 66 publications

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“…The stellar halo is The Astrophysical Journal, 820:58 (8pp), 2016 March 20 doi:10.3847/0004-637X/820/1/58 now known to be inhabited by a variety of spatial and kinematic stellar substructure, from globular clusters (GCs) and dwarf galaxies to extended stellar clouds and streams (see, e.g., Willman et al 2005;Belokurov et al 2006Belokurov et al , 2007. In fact, recent simulations based on hierarchical models of structure formation predict that most halo stars were brought by the disruption of the Galactic substructures (Bullock et al 2001).…”

Section: Introductionmentioning

confidence: 99%

The Phoenix Stream: A Cold Stream in the Southern Hemisphere

Balbinot¹,

Yanny²,

Li³

et al. 2016

ApJ

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We report the discovery of a stellar stream in the Dark Energy Survey Year 1 (Y1A1) data. The discovery was made through simple color-magnitude filters and visual inspection of the Y1A1 data. We refer to this new object as the Phoenix stream, after its resident constellation. After subtraction of the background stellar population we detect a clear signal of a simple stellar population. By fitting the ridge line of the stream in color-magnitude space, we find that a stellar population with age τ=11.5±0.5 Gyr and [Fe/H]<−1.6, located 17.5±0.9 kpc from the Sun, gives an adequate description of the stream stellar population. The stream is detected over an extension of 8°.1 (2.5 kpc) and has a width of ∼54 pc assuming a Gaussian profile, indicating that a globular cluster (GC) is a probable progenitor. There is no known GC within 5 kpc that is compatible with being the progenitor of the stream, assuming that the stream traces its orbit. We examined overdensities (ODs) along the stream, however, no obvious counterpart-bound stellar system is visible in the coadded images. We also find ODs along the stream that appear to be symmetrically distributed-consistent with the epicyclic OD scenario for the formation of cold streams-as well as a misalignment between the northern and southern part of stream. Despite the close proximity we find no evidence that this stream and the halo cluster NGC 1261 have a common accretion origin linked to the recently found EriPhe OD.

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Section: Introductionmentioning

confidence: 99%

The Phoenix Stream: A Cold Stream in the Southern Hemisphere

Balbinot¹,

Yanny²,

Li³

et al. 2016

ApJ

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“…The deep, wide-field imaging of SDSS facilitated the discovery and characterization of dozens of faint dwarf galaxies and globular clusters (GCs) in and around the Milky Way (MW; e.g., Willman et al 2005aWillman et al , 2005bBelokurov et al 2006Belokurov et al , 2007Belokurov et al , 2009Belokurov et al , 2010Zucker et al 2006aZucker et al , 2006bIrwin et al 2007;Koposov et al 2007;Kim et al 2015a)and has proven transformative for our understanding of the nature of dark matter, the impact of cosmic reionization in the local universe, and how stars form in extremely shallow gravitational potentials (e.g., Simon & Geha 2007;Bovill & Ricotti 2009;Brown et al 2014;Weisz et al 2014a).…”

Section: Introductionmentioning

confidence: 99%

A Hubble Space Telescope Study of the Enigmatic Milky Way Halo Globular Cluster Crater*

Weisz

Koposov

Dolphin

et al. 2016

ApJ

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We analyze the resolved stellar populations of the faint stellar system, Crater, based on deep optical imaging taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Crater's color-magnitude diagram (CMD) extends ∼4 mag below the oldest main-sequence (MS) turnoff. Structurally, we find that Crater has a half-light radius of ∼20 pc and no evidence for tidal distortions. We modelCrater's CMD as a simple stellar population (SSP) and alternatively by solving for its full star formation history. In both cases, Crater is welldescribed by an SSP with an age of ∼7.5 Gyr, a metallicity of [M/H]∼−1.65, a total stellar mass of M 1e4  M , anda luminosity of~-M 5.3V , located at a distance of d∼145 kpc, with modest uncertainties due to differences in the underlying stellar evolution models. We argue that the sparse sampling of stars above the turnoff and subgiant branch are likely to be 1.0-1.4  M blue stragglers and their evolved descendants, as opposed to intermediate-age MS stars. We find thatCrater is an unusually young cluster given its location in the Galaxy's outer halo. We discuss scenarios for Crater's origin, including the possibility of being stripped from the SMC or the accretion from lower-mass dwarfs such as Leo I or Carina. Despite uncertainty over its progenitor system, Crater appears to have been incorporated into the Galaxy more recently than z∼1 (8 Gyr ago), providing an important new constraint on the accretion history of the Galaxy.

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“…Discovered in 2006 in the imaging data from the Sloan Digital Sky Survey [26], Segue 1 is classified as an ultra-faint dSph, of absolute magnitude M V = −1.5 +0. 6 −0.8 .…”

Section: Introductionmentioning

confidence: 99%

Optimized Dark Matter Searches in Deep Observations of Segue 1 with MAGIC

Aleksić

2016

Springer Theses

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Abstract. We present the results of stereoscopic observations of the satellite galaxy Segue 1 with the MAGIC Telescopes, carried out between 2011 and 2013. With almost 160 hours of good-quality data, this is the deepest observational campaign on any dwarf galaxy performed so far in the very high energy range of the electromagnetic spectrum. We search this large data sample for signals of dark matter particles in the mass range between 100 GeV and 20 TeV. For this we use the full likelihood analysis method, which provides optimal sensitivity to characteristic gamma-ray spectral features, like those expected from dark matter annihilation or decay. In particular, we focus our search on gamma-rays produced from different final state Standard Model particles, annihilation with internal bremsstrahlung, monochromatic lines and box-shaped signals. Our results represent the most stringent constraints to the annihilation cross-section or decay lifetime obtained from observations of satellite galaxies, for masses above few hundred GeV. In particular, our strongest limit (95% confidence level) corresponds to a ∼500 GeV dark matter particle annihilating into τ + τ − , and is of order σ ann v ≃ 1.2×10 −24 cm 3 s −1 -a factor ∼40 above the σ ann v thermal value.

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Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions

Cited by 687 publications

References 66 publications

The Phoenix Stream: A Cold Stream in the Southern Hemisphere

The Phoenix Stream: A Cold Stream in the Southern Hemisphere

A Hubble Space Telescope Study of the Enigmatic Milky Way Halo Globular Cluster Crater*

Optimized Dark Matter Searches in Deep Observations of Segue 1 with MAGIC

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