Discovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph Galaxy With Observations from the APOGEE Project

dc.contributor.utaustinauthorShetrone, Matthewen_US
dc.creatorMajewski, Steven R.en_US
dc.creatorHasselquist, Stenen_US
dc.creatorLokas, Ewa L.en_US
dc.creatorNidever, David L.en_US
dc.creatorFrinchaboy, Peter M.en_US
dc.creatorGarcia Perez, Ana E.en_US
dc.creatorJohnston, Kathryn V.en_US
dc.creatorMeszaros, Szabolcsen_US
dc.creatorShetrone, Matthewen_US
dc.creatorAllende Prieto, Carlosen_US
dc.creatorBeaton, Rachael L.en_US
dc.creatorBeers, Timothy C.en_US
dc.creatorBizyaev, Dmitryen_US
dc.creatorCunha, Katiaen_US
dc.creatorDamke, Guillermoen_US
dc.creatorEbelke, Garretten_US
dc.creatorEisenstein, Daniel J.en_US
dc.creatorHearty, Freden_US
dc.creatorHoltzman, Jonen_US
dc.creatorJohnson, Jennifer A.en_US
dc.creatorLaw, David R.en_US
dc.creatorMalanushenko, Viktoren_US
dc.creatorMalanushenko, Elenaen_US
dc.creatorO'Connell, Robert W.en_US
dc.creatorOravetz, Danielen_US
dc.creatorPan, Kaikeen_US
dc.creatorSchiavon, Ricardo P.en_US
dc.creatorSchneider, Donald P.en_US
dc.creatorSimmons, Audreyen_US
dc.creatorSkrutskie, Michael F.en_US
dc.creatorSmith, Verne V.en_US
dc.creatorWilson, John C.en_US
dc.creatorZasowski, Gailen_US
dc.description.abstractThe dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy are explored using high-resolution (R similar to 22,500), H-band, near-infrared spectra of over 1000 giant stars in the central 3 deg(2) of the system, of which 328 are identified as Sgr members. These data, among some of the earliest observations from the Sloan Digital Sky Survey III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the largest published sample of high resolution Sgr dSph spectra to date, reveal a distinct gradient in the velocity dispersion of Sgr from 11 to 14 km s(-1) for radii > 0 degrees.8 from center to a dynamical cold point of 8 km s(-1) in the Sgr center-a trend differing from that found in previous kinematical analyses of Sgr over larger scales that suggests a more or less flat dispersion profile at these radii. Well-fitting mass models with either cored and cusped dark matter distributions can be found to match the kinematical results, although the cored profile succeeds with significantly more isotropic stellar orbits than required for a cusped profile. It is unlikely that the cold point reflects an unusual mass distribution. The dispersion gradient may arise from variations in the mixture of populations with distinct kinematics within the dSph; this explanation is suggested (e. g., by detection of a metallicity gradient across similar radii), but not confirmed, by the present data. Despite these remaining uncertainties about their interpretation, these early test data (including some from instrument commissioning) demonstrate APOGEE's usefulness for precision dynamical studies, even for fields observed at extreme airmasses.en_US
dc.description.departmentMcDonald Observatoryen_US
dc.description.sponsorshipNational Science Foundation (NSF) AST11-09718en_US
dc.description.sponsorshipPolish National Science Centre NN203580940en_US
dc.description.sponsorshipAlfred P. Sloan Foundationen_US
dc.description.sponsorshipNational Science Foundationen_US
dc.description.sponsorshipUS Department of Energy Office of Scienceen_US
dc.description.sponsorshipUniversity of Arizonaen_US
dc.description.sponsorshipBrookhaven National Laboratoryen_US
dc.description.sponsorshipUniversity of Cambridgeen_US
dc.description.sponsorshipCarnegie Mellon Universityen_US
dc.description.sponsorshipUniversity of Floridaen_US
dc.description.sponsorshipHarvard Universityen_US
dc.description.sponsorshipInstituto de Astrofisica de Canariasen_US
dc.description.sponsorshipJohns Hopkins Universityen_US
dc.description.sponsorshipLawrence Berkeley National Laboratoryen_US
dc.description.sponsorshipMax Planck Institute for Astrophysicsen_US
dc.description.sponsorshipMax Planck Institute for Extraterrestrial Physicsen_US
dc.description.sponsorshipNew Mexico State Universityen_US
dc.description.sponsorshipNew York Universityen_US
dc.description.sponsorshipOhio State Universityen_US
dc.description.sponsorshipPennsylvania State Universityen_US
dc.description.sponsorshipUniversity of Portsmouthen_US
dc.description.sponsorshipPrinceton Universityen_US
dc.description.sponsorshipUniversity of Tokyoen_US
dc.description.sponsorshipUniversity of Utahen_US
dc.description.sponsorshipVanderbilt Universityen_US
dc.description.sponsorshipUniversity of Virginiaen_US
dc.description.sponsorshipUniversity of Washingtonen_US
dc.description.sponsorshipYale Universityen_US
dc.identifier.citationMajewski, Steven R., Sten Hasselquist, Ewa L. ?okas, David L. Nidever, Peter M. Frinchaboy, Ana E. García Pérez, Kathryn V. Johnston et al. "Discovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph Galaxy with Observations from the APOGEE Project." The Astrophysical Journal Letters, Vol. 777, No. 1 (Nov., 2013): L13.en_US
dc.relation.ispartofserialAstrophysical Journal Lettersen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectgalaxies: dwarfen_US
dc.subjectgalaxies: individual (sagittarius dsph)en_US
dc.subjectgalaxies: kinematics and dynamicsen_US
dc.subjectgalaxies: stellaren_US
dc.subjectgalaxies: structureen_US
dc.subjectdwarf spheroidal galaxyen_US
dc.subjectdark-matter distributionen_US
dc.subjectsky survey viewen_US
dc.subjectacs surveyen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleDiscovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph Galaxy With Observations from the APOGEE Projecten_US

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