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Abstract:
Individual extragalactic stars that are flux magnified by hundred- to thousand-folds have been recently discovered in deep images of gravitationally lensed caustic-crossing galaxies behind galaxy cluster lenses. The phenomenology of those highly magnified extragalactic stars are sensitive to a wide range of granular structures in the lens mass distribution. I will explain how those, either individually or in groups, are inevitably subject to stochastic microlensing. I will propose highly magnified stars as astrometric probes of galaxy-free dark matter subhalos predicted in the cold dark matter model, and as practical probes of the possible dark matter ``minihalos’’ made of axion particles. Finally, I will present a recently developed statistical theory to accurately quantify the magnification statistics of highly magnified sources as a result of random microlensing.
Biography:
Liang Dai received his BS in physics at Peking University, and his PhD in physics at Johns Hopkins University. After that he was an Einstein Postdoctoral Fellow and a John Bahcall Postdoctoral Fellow at the Institute for Advanced Study in Princeton. Liang Dai recently joined University of California, Berkeley as a junior professor of astrophysics.
Zoom link： https://zoom.com.cn/j/93579891950
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