The Bulge Radial Velocity Assay (BRAVA): II. Complete Sample and Data Release

TL;DR

The BRAVA survey provides extensive radial velocity data of M-type giants in the Galactic bulge, confirming cylindrical rotation, fitting bar models, and revealing a metallicity gradient, while offering a comprehensive data catalog for further research.

Contribution

This work presents a large new dataset of radial velocities, extending the rotation curve, confirming model predictions, and analyzing metallicity gradients in the Galactic bulge.

Findings

Confirmed cylindrical rotation at multiple latitudes.

Extended rotation curve to 2.8 kpc from the Galactic Center.

Detected a vertical metallicity gradient.

Abstract

We present new radial velocity measurements from the Bulge Radial Velocity Assay (BRAVA), a large scale spectroscopic survey of M-type giants in the Galactic bulge/bar region. The sample of ~4500 new radial velocities, mostly in the region -10 deg < l < +10 deg and b ~ -6 deg more than doubles the existent published data set. Our new data extend our rotation curve and velocity dispersion profile to +20 deg, which is ~2.8 kpc from the Galactic Center. The new data confirm the cylindrical rotation observed at -6 deg and -8 deg, and are an excellent fit to the Shen et al. (2010) N-body bar model. We measure the strength of the TiO molecular band as a first step towards a metallicity ranking of the stellar sample, from which we confirm the presence of a vertical abundance gradient. Our survey finds no strong evidence of previously unknown kinematic streams. We also publish our complete catalog of radial velocities, photometry, TiO band strengths, and spectra, which is available at the IRSA archive: http://irsa.ipac.caltech.edu/ as well as at UCLA: http://brava.astro.ucla.edu/.