Role of dense matter in tidal deformations of inspiralling neutron stars and in gravitational waveforms with unified equations of state

Abstract

The role of dense-matter properties in the tidal deformability of a cold nonaccreted neutron star is further investigated. Using the set of Brussels-Montreal unified equations of state, we have computed the gravitoelectric Love numbers k and the gravitomagnetic Love numbers j up to = 5. Their relative importance and their sensitivity to the symmetry energy and the neutron-matter stiffness are numerically assessed. Their impact on the phase of the gravitational-wave signal emitted by binary neutron star inspirals is also discussed.

Dark Matter Effects on the Compact Star Properties

“…Analogous to the electromagnetic radiation, here also, the gravitational field is generated from the two types of tidal fields, i.e., (i) electric (even parity or polar) E L and (ii) magnetic (odd parity or axial) M L fields, where L represents the space indices. These two fields induce a mass multipole moment (Q L ) and a current multipole moment (S L ), which are defined as [32,78]:…”

“…Both the mass and current multipole moments come into the picture in general relativity as compared to the Newtonian dynamics, where only the mass multipole moment plays a role. The gravitoelectric (k l ) and gravitomagnetic Love numbers (j l ) are related with the deformability parameters λ l and σ l , respectively, as [32]:…”

“…The dimensionless tidal deformability parameters correspond to both electric Λ l and magnetic Σ l multipole moments, which are quite useful to express the tidal deformability of the BNSs. These quantities are often used conveniently in various measurements and related with the Love numbers and compactness of the star C with the relation [32]:…”

“…To calculate these tidal Love numbers along with the dimensionless tidal deformability Λ l and Σ l , we adopt the formalism developed in Ref. [32].…”

“…GWs discoveries of BNS mergers can also be a novel probe for nuclear physics as they encode information about the EOS in neutron-rich dense matter through finitesize effects and also provide information on NS properties, such as the mass and tidal deformability [19][20][21][22][23][24][25][26][27][28][29][30][31][32]. In the NS-NS binary, the tidal bulges of the stars affect each other, which draws energy out of the orbit and slightly accelerates the merger-indicating that the GW signal is phase-shifted relative to a merger of tideless point-masses.…”