KINEMATICS AT THE EDGE OF THE GALACTIC BULGE: EVIDENCE FOR CYLINDRICAL ROTATION

Journal Article · Thu Sep 10 04:00:00 EDT 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/702/2/L153; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21335990

Howard, Christian D; Rich, R Michael; Clarkson, Will; Mallery, Ryan ^[1]; Kormendy, John ^[2]; De Propris, Roberto ^[3]; Robin, Annie C ^[4]; Fux, Roger ^[5]; Reitzel, David B ^[6]; Zhao, HongSheng ^[7]; Kuijken, Konrad ^[8]; Koch, Andreas ^[9]

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1. Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)
2. Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States)
3. Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)
4. Observatoire de Besancon, Institut Utinam, CNRS-UMR 6213, Universite de Franche-Comte, BP1615, 25010 Besancon (France)
5. Observatoire de Geneve, Universite de Geneve, 51 Ch. des Maillettes, 1290 Sauverny (Switzerland)
6. Griffith Observatory, 2800 East Observatory Road, Los Angeles, CA 90027 (United States)
7. SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS (United Kingdom)
8. Leiden Observatory, Leiden University, P.O. Box 9513, 2300RA Leiden (Netherlands)
9. Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom)

We present new results from BRAVA, a large-scale radial velocity survey of the Galactic bulge, using M giant stars selected from the Two Micron All Sky Survey catalog as targets for the Cerro Tololo Inter-American Observatory 4 m Hydra multi-object spectrograph. The purpose of this survey is to construct a new generation of self-consistent bar models that conform to these observations. We report the dynamics for fields at the edge of the Galactic bulge at latitudes b = -8 deg. and compare to the dynamics at b = -4 deg. We find that the rotation curve V(r) is the same at b = -8 deg. as at b = -4 deg. That is, the Galactic boxy bulge rotates cylindrically, as do boxy bulges of other galaxies. The summed line-of-sight velocity distribution at b = -8 deg. is Gaussian, and the binned longitude-velocity plot shows no evidence for either a (disk) population with cold dynamics or for a (classical bulge) population with hot dynamics. The observed kinematics are well modeled by an edge-on N-body bar, in agreement with published structural evidence. Our kinematic observations indicate that the Galactic bulge is a prototypical product of secular evolution in galaxy disks, in contrast with stellar population results that are most easily understood if major mergers were the dominant formation process.

• OSTI ID: 21335990
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 2 Vol. 702; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GALACTIC EVOLUTION
GALAXIES
GIANT STARS
RADIAL VELOCITY
ROTATION