Abstract
The recent detection of gravitational waves from a neutron star merger was a significant step towards constraining the nuclear matter equation of state by using the tidal Love numbers (TLNs) of the merging neutron stars. Measuring or constraining the neutron star TLNs allows us in principle to exclude or constraint many equations of state. This approach, however, has the drawback that many modified theories of gravity could produce deviations from General Relativity similar to the deviations coming from the uncertainties in the equation of state. The first and the most natural step in resolving the mentioned problem is to quantify the effects on the TLNs from the modifications of General Relativity. With this motivation in mind, in the present paper we calculate the TLNs of (non-rotating) neutron stars in R^2-gravity. More precisely, by solving numerically the perturbation equations, we calculate explicitly the polar and the axial l=2 TLNs for three characteristic realistic equations of state and compare the results to General Relativity. Our results show that while the polar TLNs are slightly influenced by the R^2 modification of General Relativity, the axial TLNs can be several times larger (in terms of the absolute value) compared to the general relativistic case.
Highlights
The tidal Love numbers (TLNs) characterize the response of a body to an external tidal force [17,18]
The recent detection of gravitational waves from a neutron star merger was a significant step towards constraining the nuclear matter equation of state by using the tidal Love numbers (TLNs) of the merging neutron stars
Our results show that while the polar TLNs are slightly influenced by the R2 modification of General Relativity, the axial TLNs can be several times larger compared to the general relativistic case
Summary
The TLNs characterize the response (deformability) of a body to an external tidal force [17,18]. A natural step is to calculate the TLN of neutron stars in a broader class of alternative theories of gravity. A way to circumvent this problem is to consider an alternative theory of gravity with finite range scalar forces (see for example [32]). In this way the analytical GR solution can be used in the far region from the star where the effective scalar field drops off exponentially and is practically zero. It is evident that f (R) theories belong to the class of modified gravity with finite range scalar forces, that would be very important later when calculating the TLN of neutron stars.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
