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Stellar kinematics and metallicities in the ultra-faint dwarf galaxy Reticulum II

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Stellar kinematics and metallicities in the ultra-faint dwarf galaxy Reticulum II

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Título Stellar kinematics and metallicities in the ultra-faint dwarf galaxy Reticulum II
Autor Simon, Josh D.
Drlica-Wagner, Alex
Li, T. S.
Nord, Brian Dennis
Geha, Marla
Bechtol, Keith
Balbinot, Eduardo
Buckley-Geer, Elizabeth
Lin, H.
Marshall, Jennifer L.
Santiago, Basilio Xavier
Strigari, Louis E.
Wang, M.
Wechsler, Risa H.
Yanny, Brian
Abbott, Timothy M. C.
Bauer, Anne Hollister
Bernstein, Gary M.
Bertin, Emmanuel
Brooks, D.
Burke, David Lyle
Capozzi, Diego
Carnero Rosell, Aurelio
Carrasco Kind, Matías
D'Andrea, Christopher B.
Costa, Luiz N. da
DePoy, Darren L.
Desai, S.
Diehl, H. Thomas
Dodelson, Scott
Cunha, Carlos Eduardo
Estrada, Juan
Evrard, August E.
Fausti Neto, Angelo
Fernandez, Enrique
Finley, David A.
Flaugher, Brenna
Frieman, Joshua A.
Gaztañaga, Enrique
Gerdes, David W.
Gruen, Daniel
Gruendl, Robert A.
Honscheid, K.
James, David J.
Kent, Stephen M.
Kuehn, Kyler
Kuropatkin, Nikolay P.
Lahav, Ofer
Maia, Marcio Antonio Geimba
March, Marisa Cristina
Martini, Paul
Miller, Christopher J.
Miquel, Ramon
Ogando, Ricardo L.C.
Romer, Anita K.
Roodman, Aaron
Romer, Anita K.
Sako, Masao
Sanchez-Alvaro, Eusebio
Schubnell, Michael
Sevilla Noarbe, Ignacio
Smith, Robert Christopher
Soares-Santos, Marcelle
Sobreira, Flávia
Suchyta, Eric
Swanson, Molly E. C.
Tarle, Gregory
Thaler, Jon J.
Tucker, Douglas L.
Vikram, Vinu
Walker, Alistair
Wester, William Carl
DES Collaboration
Abstract We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8  0.5 km s-1 and a velocity dispersion of 3.3  0.7 km s-1. The mass-to-light ratio of Ret II within its half-light radius is 470  210 M L, demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83 km s-1, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3 dex in metallicity, with a dispersion of 0.28 ± 0.09 dex, and we identify several extremely metal-poor stars with [Fe/H] < -3. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of [Fe/H] = -2.65  0.07, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is log10 (J) 18.8 0.6 GeV cm =  2 -5 within 0 ◦. 2, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies.
Contido em The astrophysical journal. Bristol. Vol. 808, no. 1 (July 2015), 95, 14 p.
Assunto Composicao estelar
Dinamica estelar
Espectros estelares
Galaxia
Grande Nuvem de Magalhães
Materia escura
Pequena Nuvem de Magalhães
[en] Dark matter
[en] Galaxies: dwarf
[en] Galaxies: individual (Reticulum II)
[en] Galaxies: stellar content
[en] Local group
[en] Stars: abundances
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/126987
Arquivos Descrição Formato
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