Novel stellar astrophysics from extended gravity

¹ Institute of Physics, Mathematics and IT, “I. Kant” Baltic Federal University - Kaliningrad, 236041, Russia
² Dipartimento di Fisica “E. Pancini”, Università di Napoli “Federico II” - Napoli, Italy
³ Istituto Nazionale di Fisica Nucleare (INFN), sez. di Napoli - Via Cinthia 9, I-80126 Napoli, Italy
⁴ ICREA - Passeig Luis Companys 23, 08010 Barcelona, Spain
⁵ Institute of Space Sciences (IEEC- CSIC) - C. Can Magrans s/n, 08193 Barcelona, Spain
⁶ Department of Physics, Aristotle University of Thessaloniki - Thessaloniki 54124, Greece

^(a) artyom.art@gmail.com
^(b) capozziello@na.infn.it
^(c) odintsov@ieec.uab.es
^(d) v.k.oikonomou1979@gmail.com, voikonomou@auth.gr (corresponding author)

Received: 15 May 2021
Accepted: 2 June 2021

Abstract

Novel implications on neutron stars come from extended gravity. Specifically, the GW190814 event indicated the probability of having large mass stars in the mass gap region . If the secondary component of GW190814 is a neutron star, such large masses are marginally supported by General Relativity (GR), since a very stiff Equation of State (EoS) would be needed to describe such large mass neutron stars, which would be incompatible with the GW170817 event, without any modification of gravity. In view of the two groundbreaking gravitational wave observations, we critically discuss the elevated role of extensions of GR towards the successful description of the GW190814 event, and we also speculate in a quantitative way on the important issue of the largest allowed neutron star mass.