LISA, Extreme Mass Ratio Inspirals, and new fundamental fields in the gravity sector

Описание: "Testing the nature of gravity and the validity of Einstein's
theory in the strong field regime is one of the most ambitious
goals of gravitational wave (GW) detectors, and a primary target
for the space satellite LISA.

Among binary sources observable by LISA, extreme mass ratio inspirals
(EMRIs) in which a stellar mass object follows hundreds of thousands
of orbits around a supermassive black hole, harbour the potential for
very precise tests of gravity.

This simplest modifications of General Relativity (GR) predict the
existence of scalar fields which modify the gravitational interaction.
However modelling EMRIs and their GW emission beyond GR is a
major challenge, so far slowed down by the mathematical complexity
of the problem.

In this talk I will present a new study showing that, for a vast
class of theories in which compact objects are endowed with a scalar
field witch couples to the gravity sector,
the description of EMRIs greatly simplifies, reducing the problem to the motion
of a charged body around a Kerr black hole. In particular I
will show how all the information on the GR modifications is
universally captured by a single parameter,
the scalar charge of the stellar mass object.
This promises drastic simplifications in terms of waveform
modelling, and offers the opportunity to use EMRIs for agnostic
strong field tests of gravity. I'll present some recent results on the
constraints that LISA can potentially be able to infer on the scalar
charge, and how they can be mapped to bounds on the fundamental
parameters which control GR deviations in specific modified theories
of gravity"

Author and Presenter: Andrea Maselli