# Item

ITEM ACTIONSEXPORT

Released

Journal Article

#### Binary neutron star mergers in massive scalar-tensor theory: Quasiequilibrium states and dynamical enhancement of the scalarization

##### MPS-Authors

##### External Resource

No external resources are shared

##### Fulltext (restricted access)

There are currently no full texts shared for your IP range.

##### Fulltext (public)

2309.01709.pdf

(Preprint), 2MB

PhysRevD.108.064057.pdf

(Publisher version), 2MB

##### Supplementary Material (public)

There is no public supplementary material available

##### Citation

Kuan, H.-J., Van Aelst, K., Lam, A. T. L., & Shibata, M. (2023). Binary neutron
star mergers in massive scalar-tensor theory: Quasiequilibrium states and dynamical enhancement of the scalarization.* Physical Review D,* *108*(6): 064057. doi:10.1103/PhysRevD.108.064057.

Cite as: https://hdl.handle.net/21.11116/0000-000D-B20B-E

##### Abstract

We study quasi-equilibrium sequences of binary neutron stars in the framework

of Damour-Esposito-Farese-type scalar-tensor theory of gravity with a massive

scalar field, paying particular attention to the case where neutron stars are

already spontaneously scalarized at distant orbits, i.e., in the high coupling

constant case. Although scalar effects are largely quenched when the separation

$a$ is $\gtrsim 3$--$6$ times of the Compton length-scale that is defined by

the scalar mass, we show that the interaction between the scalar fields of the

two neutron stars generates a scalar cloud surrounding the binary at the price

of orbital energy when $a \lesssim 3$--$6$ times of the Compton length-scale.

This enables us to constrain the scalar mass $m_\phi$ from gravitational-wave

observations of binary neutron star mergers by inspecting the dephasing due to

such phenomenon. In particular, the event GW170817 is suggestive of a

constraint of $m_\phi \gtrsim 10^{-11}$ eV and the coupling strength should be

mild if the neutron stars in this system were spontaneously scalarized.

of Damour-Esposito-Farese-type scalar-tensor theory of gravity with a massive

scalar field, paying particular attention to the case where neutron stars are

already spontaneously scalarized at distant orbits, i.e., in the high coupling

constant case. Although scalar effects are largely quenched when the separation

$a$ is $\gtrsim 3$--$6$ times of the Compton length-scale that is defined by

the scalar mass, we show that the interaction between the scalar fields of the

two neutron stars generates a scalar cloud surrounding the binary at the price

of orbital energy when $a \lesssim 3$--$6$ times of the Compton length-scale.

This enables us to constrain the scalar mass $m_\phi$ from gravitational-wave

observations of binary neutron star mergers by inspecting the dephasing due to

such phenomenon. In particular, the event GW170817 is suggestive of a

constraint of $m_\phi \gtrsim 10^{-11}$ eV and the coupling strength should be

mild if the neutron stars in this system were spontaneously scalarized.