Title: Probing Exotic Physics with Pulsating White Dwarfs

Dr. Agnes Kim
UT Austin

We now have a good measurement of the cooling rate of the cool pulsating white dwarf G117-B15A. In the near future, we will have equally well determined cooling rates for other pulsating white dwarfs, including R548. The ability to measure their cooling rates offers us a unique way to study weakly interacting particles that would contribute to their cooling, such as axions. I begin by presenting results of the asteroseismological analysis of observationally similar G117-B15A and R548, using a fine grid search method. This is the first systematic, 4 parameter asteroseismolgy of those two stars. Based on these results, I compute rates of period change (dP/dt) for the 215s mode in G117-B15A and the 213s mode in R548, first for models without axions, and then for models with axions of increasing mass. Given the region of parameter space occupied by the models, I estimate error bars on the calculated dP/dt using Monte Carlo simulations. Together with the observed dP/dt for G117-B15A, this analysis yields strong limits on the DFSZ axion mass. This method can potentially be applied to other weakly interacting particles that would be emitted in the interiors of white dwarf stars. I present preliminary results on a similar analysis of a hotter pulsating white dwarf, EC20058, to constrain plasmon neutrino emission rates.

UT Arlington Physics