Jul 5 – 10, 2021
Europe/Rome timezone

Neutron stars in f (R, T ) gravity using realistic equations of state in the light of massive pulsars and GW170817

Jul 5, 2021, 6:45 PM
Invited talk in the parallel session Compact stars as laboratories for testing strong gravity Compact Stars as Laboratories for Testing Strong Gravity


Manuel Malheiro (Instituto Tecnológico de Aeronáutica)


In this work we investigate neutron stars (NS) in f (R, T ) gravity
for the case R + 2λT , R is the Ricci scalar, and T the trace of the
energy-momentum tensor. The hydrostatic equilibrium equations are
solved considering realistic equations of state (EOS). The NS masses
and radii obtained are subject to a joint constrain from massive pulsars
and the event GW170817. The parameter λ needs to be negative as in
previous NS studies, however, we found a minimum value for it due to the existence
of the NS crust. The pressure in this modified theory of gravity depends on the
inverse of the sound velocity. Since, this velocity is lower in the crust, |λ| needs to be very small. We found that the increment in the star mass is less
than 1%, much smaller than previous ones obtained not considering the
realistic stellar structure, and the star radius cannot become larger, its
changes compared to GR is less than 3.6% in all cases. The finding that
using several relativistic and non-relativistic models the variation on
the NS mass and radius is almost the same for all the EsoS, manifests
that our results are insensitive to the high-density part of the EOS.
It confirms that stellar mass and radii obtained in f(R,T) depends only on the NS crust, where the EoS is essentially the same for all the models. Finally, we highlight that our results indicate that conclusions obtained from NS studies
done in modified theories of gravity without using realistic EsoS that
describe correctly the NS interior can be unreliable.

Primary author

Manuel Malheiro (Instituto Tecnológico de Aeronáutica)

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