1. , School of Physics A billion points of light Hugh Garsden, PhD Student Supervisor: Geraint Lewis OzLens 2008

2. , School of Physics Area of Research … Anomalous flux ratios –Don’t fit theory/models Simulations show – due to microlensing – if add smooth matter – produces high demagnifications Quasar Microlensing at High Magnification and the Role of Dark Matter: Enhanced Fluctuations and Suppressed Saddle Points. Schechter and Wambsganss, Ap. J. 2002. Quasar MG 0414+0534

3. , School of Physics Area of Research … Two mass components Microlenses (M  ) + smooth

4. , School of Physics Area of Research … Suggests magnification distributions are dependant on mass function Further simulations where smooth matter is “broken up” into compact matter objects –Compact objects all the same mass, but vary that Qualitative Aspects of Quasar Microlensing with Two Mass Components: Magnification Patterns and Probability Distributions. Schechter, Wambsganss, Lewis, Ap. J. 2004.

5. , School of Physics Area of Research … Two mass components x Two scenarios Microlenses (M  )+ smoothMicrolenses (M  )+ compact

6. , School of Physics 10% M  (# lenses = 1,133) 90% smooth 10% M  (# lenses = 1,133) 90% 10 -3 M  (# lenses = 10,205,331) There are large scale similarities

7. , School of Physics Area of Research … Compact matter can appear as smooth matter. Size of source is important. Quasar Microlensing: When Compact Masses Mimic Smooth Matter. Lewis and Gil-Merino, Ap. J., 2006. Smooth Matter and Source Size in Microlensing Simulations of Gravitationally Lensed Quasars. Bate, Webster, Wyithe, Mon. Not. R. Astron. Soc., 2008. Scale at which dark matter can be detected? –Suppose compact masses are dark matter candidates –Might appear as smooth matter

8. , School of Physics Area of Research Ongoing area of research –Microlensing Simulations –Bi-modal mass distributions –Source size Reached an impasse significant numerical challenges number of microlensing masses “… significant numerical challenges due to the number of microlensing masses that are needed [in simulations]” Probing the Nature of Dark Matter With Gravitational Lensing. Lewis, Manchester Microlensing Conference, 2008.

9. , School of Physics This is where I come in … I can run bigger simulations with new software

10. , School of Physics Software microlens by Joachim Wambsganss Gold standard for microlensing simulations Sims limited to ~10 7 lenses due to memory Modify –Put lenses on disk –Parallelize One billion lenses in 3-4 days on supercomputer

11. , School of Physics Why one billion? “Because it’s there” “Because I can” Really – needed for further simulations, up to 1.3 billion

12. , School of Physics 10% M  (# lenses = 1,133) 90% 10 -5 M  (# lenses = 1,020,533,131)

13. , School of Physics Continuing work Developing the software Probe the parameter space with more simulations More science coming!!! Watch this space. Acknowledgement: Thanks to The Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, for use of their supercomputer.