Lunch talk on Apr. 25, 2022

Closing a spontaneous-scalarization window with binary pulsars

Speaker:Junjie Zhao (BNU)

Venue:Video Conference

Time:12:30 PM, Monday, Apr. 25, 2022

Abstract:

Benefitting from the unequaled precision of the pulsar timing technique, binary pulsars are important testbeds of gravity theories, providing some of the tightest bounds on alternative theories of gravity. One class of well-motivated alternative gravity theories, the scalar-tensor gravity, predicts large deviations from general relativity for neutron stars through a nonperturbative phenomenon known as spontaneous scalarization. This effect, which can not be tested in the Solar System, can now be tightly constrained using the latest results from the timing of a set of 7 binary pulsars. Using new timing results, we constrain the neutron star's effective scalar coupling, which describes how strongly neutron stars couple to the scalar field, to a tighter level in a Bayesian analysis. It excludes the possibility of spontaneous scalarization of neutron stars, at least within such a class of scalar-tensor gravity theories.

Report PPT:SWIFAR_Junjie Zhao.pdf