Bibliographic Details
| Title: |
Comparing Observed Stellar Kinematics and Surface Densities in a Low Latitude Bulge Field to Galactic Population Synthesis Models |
| Authors: |
Terry, Sean K., Barry, Richard K., Bennett, David P., Bhattacharya, Aparna, Anderson, Jay, Penny, Matthew T. |
| Publication Year: |
2019 |
| Collection: |
Astrophysics |
| Subject Terms: |
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Astrophysics of Galaxies |
| More Details: |
We present an analysis of Galactic bulge stars from Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the Stanek window (l,b=[0.25,-2.15]) from two epochs approximately two years apart. This dataset is adjacent to the provisional Wide-field Infrared Survey Telescope (WFIRST) microlensing field. Proper motions are measured for approximately 115,000 stars down to 28th mag in V band and 25th mag in I band, with accuracies of 0.5 mas yr$^{-1}$ (20 km s$^{-1}$) at I $\approx$ 21. A cut on the longitudinal proper motion $\mu_l$ allows us to separate disk and bulge populations and produce bulge-only star counts that are corrected for photometric completeness and efficiency of the proper-motion cut. The kinematic dispersions and surface density in the field are compared to the nearby SWEEPS sight-line, finding a marginally larger than expected gradient in stellar density. The observed bulge star counts and kinematics are further compared to the Besan\c{c}on, Galaxia, and GalMod Galactic population synthesis models. We find that most of the models underpredict low-mass bulge stars by $\sim$33% below the main-sequence turnoff, and upwards of $\sim$70% at redder J and H wavebands. While considering inaccuracies in the Galactic models, we give implications for the exoplanet yield from the WFIRST microlensing mission.
Comment: 18 pages, 10 figures. Published in ApJ |
| Document Type: |
Working Paper |
| DOI: |
10.3847/1538-4357/ab629b |
| Access URL: |
http://arxiv.org/abs/1910.02297 |
| Accession Number: |
edsarx.1910.02297 |
| Database: |
arXiv |
