Event rates and timescale distributions from realistic microlensing models of M31

Abstract

We provide a set of microlensing event rate maps for M31, the Andromeda Galaxy. Rates for M31 microlensing were calculated on the basis of a four component model of the lens and source populations: disk and bulge sources lensed by bulge, disk, M31 halo and Galactic halo lenses. We confirm the high rate gradient along the minor axis of M31 due to a dark halo of lenses. Furthermore, we compute the timescale distributions of events, for both Einstein times and full-width at half-maximum times. We explore how the rate contours and the timescale distributions can be used to measure the shape and extent of the microlensing halo. With one year of twice--weekly sampling, or three observing seasons, a halo MACHO fraction as small as 5% can be detected with modest ground based telescopes.

11 pages, 6 figures, matches published version

References in corpus (4)

• The Galactic disk mass-budget : I. stellar mass-function and density
• A Short Timescale Candidate Microlensing Event in the POINT-AGAPE Pixel Lensing Survey of M31
• Microlensing search towards M31
• The Brown Dwarf Mass Function from Pixel Microlensing

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• The Angstrom Project: a microlensing survey of the structure and composition of the bulge of the Andromeda galaxy
• Evidence of Halo Microlensing in M31
• Pixel lensing: Microlensing towards M31
• A new analysis of the MEGA M31 microlensing events
• The impact of spheroid stars for Macho microlensing surveys of the Andromeda Galaxy
• Monte Carlo analysis of the MEGA microlensing events towards M31
• First microlensing candidate towards M31 from the Nainital Microlensing Survey
• Influence of magnification threshold on pixel lensing optical depth, event rate and time scale distributions towards M31
• Theory of pixel lensing towards M31 -- II. The velocity anisotropy and flattening of the MACHO distribution
• Ground-based variability surveys towards Centaurus A: worthwhile or not?
• HST Imaging of MEGA Microlensing Candidates in M31
• Microlensing Surveys of M31 in the Wide Field Imaging Era