Speaker: Jeremy Sakstein

Abstract:

Screened theories of modified gravity such as chameleon models
have attracted a lot of attention over the last few years. They give
rise to order-one fifth-forces on large scales whilst masquerading as
General Relativity in our own solar system. This leaves us with the
problem of searching for them observationally. In this talk, I will
describe some recent work over the past few years using astrophysical
tests to constrain these theories. Unscreened stars situated in Dwarf
galaxies in voids can show novel effects compared with General
Relativity. They are brighter, hotter and they pulsate faster. By
exploiting these new features, we have been able to place the strongest
constraints to date and there is little room left for these theories to
hide.