Journal article
A new photometric model of the Galactic bar using red clump giants
Monthly notices of the Royal Astronomical Society, Vol.434(1), pp.595-605
09/01/2013
DOI: 10.1093/mnras/stt1045
Abstract
We present a study of the luminosity density distribution of the Galactic bar using number counts of red clump giants from the Optical Gravitational Lensing Experiment (OGLE) III survey. The data were recently published by Nataf et al. for 9019 fields towards the bulge and have 2.94 x 10(6) RC stars over a viewing area of 90.25 deg(2). The data include the number counts, mean distance modulus (mu), dispersion in mu and full error matrix, from which we fit the data with several triaxial parametric models. We use the Markov Chain Monte Carlo method to explore the parameter space and find that the best-fitting model is the E-3 model, with the distance to the GC 8.13 kpc, the ratio of semimajor and semiminor bar axis scalelengths in the Galactic plane x(0), y(0) and vertical bar scalelength z(0) x(0): y(0): z(0) approximate to 1.00: 0.43: 0.40 (close to being prolate). The scalelength of the stellar density profile along the bar's major axis is similar to 0.67 kpc and has an angle of 29 degrees.4, slightly larger than the value obtained from a similar study based on OGLE-II data. The number of estimated RC stars within the field of view is 2.78 x 10(6), which is systematically lower than the observed value. We subtract the smooth parametric model from the observed counts and find that the residuals are consistent with the presence of an X-shaped structure in the Galactic Centre, the excess to the estimated mass content is similar to 5.8 per cent. We estimate that the total mass of the bar is similar to 1.8 x 10(10) M-circle dot. Our results can be used as a key ingredient to construct new density models of the Milky Way and will have implications on the predictions of the optical depth to gravitational microlensing and the patterns of hydrodynamical gas flow in the Milky Way.
Details
- Title: Subtitle
- A new photometric model of the Galactic bar using red clump giants
- Creators
- Liang Cao - Chinese Academy of SciencesShude Mao - Chinese Academy of SciencesDavid Nataf - Australian National UniversityNicholas J. Rattenbury - University of ManchesterAndrew Gould - The Ohio State University
- Resource Type
- Journal article
- Publication Details
- Monthly notices of the Royal Astronomical Society, Vol.434(1), pp.595-605
- DOI
- 10.1093/mnras/stt1045
- ISSN
- 0035-8711
- eISSN
- 1365-2966
- Publisher
- Oxford Univ Press
- Number of pages
- 11
- Grant note
- AST-1103471 / NSF; National Science Foundation (NSF) 11203028 / NSFC; National Natural Science Foundation of China (NSFC) ST/J001562/1 / Science and Technology Facilities Council; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) Young Researcher Grant of NAOC Chinese Academy of Sciences (CAS); Chinese Academy of Sciences John Templeton Foundation ST/J001562/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) National Astronomical Observatories (NAOC)
- Language
- English
- Date published
- 09/01/2013
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701732802771
Metrics
18 Record Views