KINEMATICS AT THE EDGE OF THE GALACTIC BULGE: EVIDENCE FOR CYLINDRICAL ROTATION
- Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)
- Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States)
- Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)
- Observatoire de Besancon, Institut Utinam, CNRS-UMR 6213, Universite de Franche-Comte, BP1615, 25010 Besancon (France)
- Observatoire de Geneve, Universite de Geneve, 51 Ch. des Maillettes, 1290 Sauverny (Switzerland)
- Griffith Observatory, 2800 East Observatory Road, Los Angeles, CA 90027 (United States)
- SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS (United Kingdom)
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300RA Leiden (Netherlands)
- 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), Vol. 702, Issue 2; Other Information: DOI: 10.1088/0004-637X/702/2/L153; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-4357
- Country of Publication:
- United States
- Language:
- English
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