A consistent microlensing model for the Galactic bar

Hongsheng Zhao, R. Michael Rich, David N. Sperge

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

We compute a microlensing map for the Galactic bar. The predicted event rate and event duration distribution are consistent with the 55 events recently reported by the MACHO and OGLE collaborations. Most of the events are due to lensing by stars in the near end of the bar. Lens mass functions with about 30-60 per cent of the lens mass as brown dwarfs are rejected at 2σ-6σ levels. To make our model useful for other workers, we tabulate the optical depth of the bar and average event duration (scaled to 1-M lenses) on a grid of galactic coordinates. The distance and the proper motions of the lens and the source are derived from a consistent dynamical model of the stellar bar, which has originally been built to fit data on the stellar light and stellar/gas kinematics of the bar. We explore several alternative models, and we find that our standard model best matches the observations.

Original languageEnglish (US)
Pages (from-to)175-181
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume282
Issue number1
DOIs
StatePublished - 1996

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Dark matter
  • Galaxy: kinematics and dynamics
  • Galaxy: structure
  • Gravitational lensing
  • Stars: low-mass, brown dwarfs

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