Microlensing Maps for the Milky Way Galaxy

Abstract

At any instant, there are roughly 1000 ongoing microlensing events to sources brighter than 20th magnitude in the Milky Way Galaxy. Large-scale maps of the microlensing optical depth and the mean timescale are constructed for a number of models of the Galactic bar and disk, incorporating the effects of streaming and spiral structure. Freudenreich's model can reproduce the high optical depths towards the Bulge. It is also in good agreement with the data towards the spiral arms (except for the gamma Norma field). Spiral structure tends to increase the optical depth by about 20% and the mean timescale by about 100%. Different bar morphologies give characteristically different shaped contours, especially at low Galactic latitudes (|b| < 2 degrees). These could be traced out with a K band microlensing survey, consuming about 100 minutes per night on a telescope like VISTA.

15 pages, 5 figures, ApJ (Letters) in press

Cited by in corpus (31)

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• Separation of Stellar Populations by an Evolving Bar: Implications for the Bulge of the Milky Way
• Modelling the Galactic bar using OGLE-II Red Clump Giant Stars
• Galactic Bulge Microlensing Optical Depth from EROS-2
• The Microlensing Event Rate and Optical Depth Toward the Galactic Bulge from MOA-II
• OGLE-III Microlensing Events and the Structure of the Galactic Bulge
• Bulge Microlensing Optical Depth from EROS 2 observations
• MOA-II Galactic Microlensing Constraints: The Inner Milky Way has a Low Dark Matter Fraction and a Near Maximal Disk
• A parametric description of the 3D structure of the Galactic Bar/Bulge using the VVV survey
• Microlensing constraints on the Galactic Bulge Initial Mass Function
• Proper Motion Dispersions of Red Clump Giants in the Galactic Bulge: Observations and Model Comparisons
• Optical Depths and Timescale Distributions in Galactic Microlensing
• Blending in Gravitational Microlensing Experiments: Source Confusion And Related Systematics
• Microlensing as a probe of the Galactic structure; 20 years of microlensing optical depth studies
• High precision microlensing maps of the Galactic bulge
• Possible Solution of the long-standing discrepancy in the Microlensing Optical Depth Toward the Galactic Bulge by correcting the stellar number count
• The EROS2 search for microlensing events towards the spiral arms: the complete seven season results
• The Cold Dark Matter crisis on galactic and subgalactic scales
• Gaia Data Release 3: Microlensing Events from All Over the Sky
• Resonant Orbits and the High Velocity Peaks Towards the Bulge
• A microlensing search of 700 million VVV light curves
• The Nature of Parallax Microlensing Events Towards the Galactic Bulge
• Dark lenses through the dust: parallax microlensing events in the VVV
• Direct Lens Imaging of Galactic Bulge Microlensing Events
• Polarization in binary microlensing events
• Gravitational Lensing of Spherically Symmetric Black Holes in Dark Matter Halos
• Influence of the Galactic gravitational field on the positional accuracy of extragalactic sources
• The OGLE-II event sc5_2859 -- An example of disk-disk microlensing
• Gravitational Microlensing Event Statistics for the Zwicky Transient Facility
• Microlensing by free-floating brown dwarfs