Dark Matter (DM) is the clearest sign that the Standard Model of particle physics is incomplete. A determination of the DM particle mass will rule out entire classes of hypothetical extensions to the Standard Model, thus pointing the correct path towards New Physics. In this talk, I describe how gravitational lensing can differentiate between the two top contenders for DM: ultra-massive (WIMPs) versus ultra-light (Axion or Axion-like) particles, both hypothesized in different theoretical extensions to the Standard Model. Specifically, I show how DM in the form of ultra-light particles (mass ~10-22 eV) can resolve a two-decade old problem in gravitational lensing, whereby galaxy DM models based on ultra-massive particles leave discrepancies between the predicted and observed properties of multiply-lensed images. The increasing success of ultra-light DM particles in explaining astronomical observations, naturally predicting cores in dwarf galaxies and a suppression of low-mass halos thus resolving the missing satellite problem, together with observational evidence for solitonic cores in galaxies, is starting to tilt the scale to new physics involving ultra-light particles.
BIO
Prof. Jeremy Jin Leong Lim from University of Hongkong :
1984: BSc. at Macquarie University, Sydney, NSW, Australia
1985: BSc. (Hons) at Macquarie University, Sydney, NSW, Australia
1991: PhD at Macquarie University, Sydney, NSW, Australia & CSIRO Division of Radiophysics & Australia Telescope National Facility
1991-1992: Postdoctoral Fellow, University of Maryland
1992-1994: Research Fellow, CalTech
1994-1995: Postdoctoral Fellow, ASIAA
1995-1996: Academia Sinica Fellow, ASIAA
1996-2000: Assistant Research Fellow, ASIAA
1999-2000: Adjunct Assistant Professor, NCU
2000-2009: Associate Research Fellow, ASIAA
2007-2009: Adjunct Associate Professor, NTU
2009: Research Fellow, ASIAA
2009-present: Associate Professor, University of Hong Kong
Research interest:
Radio Interferometry
Star Formation (Low-Mass, High-Mass, and Binary Systems)
Evolved Stars (Red Giants and Planetary Nebulae)
Active Galaxies (AGNs, QSOs, and Radio Galaxies)
Cosmology (Sunyaev-Zeldovich effect)
Host: Dandan Xu
