A dwarf galaxy remnant in Canis Major: the fossil of an in-plane accretion on to the Milky Way
Nicolas F. Martin,Rodrigo A. Ibata,Michele Bellazzini,Mike Irwin,Geraint F. Lewis,Walter Dehnen +5 more
TLDR
In this article, an analysis of the asymmetries in the population of Galactic M-giant stars present in the 2MASS All Sky catalogue is presented, the most significant of which is a strong elliptical-shaped stellar over-density, close to the Galactic plane at (l = 240 ◦, b = 8 ◦ ), in the constellation of Canis Major.Abstract:
We present an analysis of the asymmetries in the population of Galactic M-giant stars present in the 2MASS All Sky catalogue. Several large-scale asymmetries are detected, the most significant of which is a strong elliptical-shaped stellar over-density, close to the Galactic plane at (l = 240 ◦ , b = 8 ◦ ), in the constellation of Canis Major. A small grouping of globular clusters (NGC 1851, NGC 1904, NGC 2298, and NGC 2808), coincident in position and radial velocity, surround this structure, as do a number of open clusters. The population of M-giant stars in this over-density is similar in number to that in the core of the Sagittarius dwarf galaxy. We argue that this object is the likely dwarf galaxy progenitor of the ring-like structure that has recently been found at the edge of the Galactic disk. A numerical study of the tidal disruption of an accreted dwarf galaxy is presented. The simulated debris fits well the extant position, distance and velocity information on the “Galactic Ring”, as well as that of the M-giant overdensities, suggesting that all these structures are the consequence of a single accretion event. The disrupted dwarf galaxy stream orbits close to the Galactic Plane, with a pericentre at approximately the Solar circle, an orbital eccentricity similar to that of stars in the Galactic thick disk, as well as a vertical scale height similar to that of the thick disk. This finding strongly suggests that the Canis Major dwarf galaxy is a building block of the Galactic thick disk, that the thick disk is continually growing, even up to the present time, and that thick disk globular clusters were accreted onto the Milky Way from dwarf galaxies in co-planar orbits.read more
Citations
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Tracing Galaxy Formation with Stellar Halos. I. Methods
TL;DR: In this paper, the authors used a hybrid semianalytic plus N-body approach to distinguish between the evolution of light and dark matter in accreted satellites, which is essential to produce a realistic stellar halo, with mass and density profile much like that of our own Galaxy, and a surviving satellite population that matches the observed number counts and structural parameter distributions of the satellite galaxies of the Milky Way.
Journal ArticleDOI
Extragalactic Globular Clusters and Galaxy Formation
Jean P. Brodie,Jay Strader +1 more
TL;DR: In this article, it was shown that metal-poor GCs formed in low-mass dark matter halos in the early universe and that their properties reflect biased galaxy assembly, while metal-rich GCs were born in the subsequent dissipational buildup of their parent galaxies.
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Galactic stellar haloes in the CDM model
Andrew P. Cooper,Shaun Cole,Carlos S. Frenk,Simon D. M. White,John C. Helly,Andrew J. Benson,G. De Lucia,Amina Helmi,Adrian Jenkins,Julio F. Navarro,Volker Springel,Jie Wang +11 more
TL;DR: In this article, a suite of high-resolution N-body simulations of individual dark matter haloes is presented, which is based on the Aquarius project, and the authors find that accreted stellar haloes are assembled between 1 < z < 7 from less than five significant progenitors.
Journal ArticleDOI
Searching for dark matter annihilation in recently discovered Milky Way Satellites with Fermi-LAT
Andrea Albert,Brandon Anderson,Keith Bechtol,Alex Drlica-Wagner,Manuel Meyer,Miguel A. Sánchez-Conde,Louis E. Strigari,M. Wood,T. M. C. Abbott,F. B. Abdalla,F. B. Abdalla,A. Benoit-Lévy,A. Benoit-Lévy,Gary Bernstein,R. A. Bernstein,E. Bertin,David J. Brooks,D. L. Burke,A. Carnero Rosell,M. Carrasco Kind,J. Carretero,Martin Crocce,Carlos E. Cunha,C. B. D'Andrea,C. B. D'Andrea,L. N. da Costa,Shantanu Desai,H. T. Diehl,J. P. Dietrich,Peter Doel,Tim Eifler,Tim Eifler,August E. Evrard,A. Fausti Neto,D. A. Finley,B. Flaugher,Pablo Fosalba,Joshua A. Frieman,D. W. Gerdes,Daniel A. Goldstein,Daniel A. Goldstein,Daniel Gruen,Robert A. Gruendl,K. Honscheid,David J. James,Steve Kent,Kyler Kuehn,N. Kuropatkin,Ofer Lahav,Tianjun Li,Marcio A. G. Maia,M. March,Jennifer L. Marshall,Paul Martini,Christopher J. Miller,Ramon Miquel,Eric H. Neilsen,Brian Nord,Ricardo L. C. Ogando,A. A. Plazas,Kevin Reil,A. K. Romer,Eli S. Rykoff,E. J. Sanchez,Basilio X. Santiago,Michael Schubnell,I. Sevilla-Noarbe,R. C. Smith,Marcelle Soares-Santos,Flavia Sobreira,E. Suchyta,M. E. C. Swanson,Gregory Tarle,Vinu Vikram,Alistair R. Walker,Risa H. Wechsler +75 more
TL;DR: In this paper, the authors search for excess gamma-ray emission coincident with the positions of confirmed and candidate Milky Way satellite galaxies using six years of data from the Fermi Large Area Telescope (LAT).
Journal ArticleDOI
A New Milky Way Dwarf Galaxy in Ursa Major
Beth Willman,Julianne J. Dalcanton,David Martínez-Delgado,David Martínez-Delgado,Andrew A. West,Michael R. Blanton,David W. Hogg,J. C. Barentine,Howard Brewington,Michael Harvanek,Scot Kleinman,Jurek Krzesinski,Jurek Krzesinski,Dan Long,Eric H. Neilsen,Atsuko Nitta,Stephanie A. Snedden +16 more
TL;DR: In this paper, the discovery of a new dwarf satellite to the Milky Way, located at (α2000, δ2000) = (15872, 5192) in the constellation of Ursa Major, was reported.
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