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News & Events

Nirmal Raj (TRIUMF)

Event Details

McDonald Institute Seminar Series

Location: Queen's University, Stirling Hall, Rm 501

Date: January 27, 2020

Time: 2:30pm - 3:30pm

Gravitational Microlensing of Non-baryonic Compact Objects

Dark matter may be in te form of non-baryonic compact objects such as axion miniclusters, compact subhalos, boson stars, and mirror stars. If these objects weigh between asteroid and solar masses, they may be discovered via gravitational microlensing, i.e. the observation of temporary brightening of a background star whose light is deflected by the transiting object — an astronomical probe that has in the past helped constrain the population of primordial black holes and baryonic MACHOs. In this talk, I discuss the microlensing properties of various non-baryonic objects with respect to their density profiles and sizes, and constrain their population using surveys by the EROS, OGLE and Subaru collaborations. I also briefly discuss the effects of the finite size of source stars and the breakdown of geometric optics.