Abstract
Pulsar timing and gravitational-wave (GW) detectors are superb laboratories to study gravity theories in the strong-field regime. Here we combine those tools to test the mono-scalar-tensor theory of Damour and Esposito-Far{\`e}se (DEF), which predicts nonperturbative scalarization phenomena for neutron stars (NSs). First, applying Markov-chain Monte Carlo techniques, we use the absence of dipolar radiation in the pulsar-timing observations of five binary systems composed of a NS and a white dwarf, and eleven equations of state (EOSs) for NSs, to derive the most stringent constraints on the two free parameters of the DEF scalar-tensor theory. Since the binary-pulsar bounds depend on the NS mass and the EOS, we find that current pulsar-timing observations leave scalarization windows, i.e., regions of parameter space where scalarization can still be prominent. Then, we investigate if these scalarization windows could be closed and if pulsar-timing constraints could be improved by laser-interferometer GW detectors, when spontaneous (or dynamical) scalarization sets in during the early (or late) stages of a binary NS (BNS) evolution. For the early inspiral of a BNS carrying constant scalar charge, we employ a Fisher matrix analysis to show that Advanced LIGO can improve pulsar-timing constraints for some EOSs, and next-generation detectors, such as the Cosmic Explorer and Einstein Telescope, will be able to improve those bounds for all eleven EOSs. Using the late inspiral of a BNS, we estimate that for some of the EOSs under consideration the onset of dynamical scalarization can happen early enough to improve the constraints on the DEF parameters obtained by combining the five binary pulsars. Thus, in the near future the complementarity of pulsar timing and direct observations of GWs on the ground will be extremely valuable in probing gravity theories in the strong-field regime.
Highlights
In general relativity (GR), gravity is mediated solely by a rank-2 tensor, namely, the spacetime metric gμν
For the early inspiral of a binary NS (BNS) carrying constant scalar charge, we employ a Fisher-matrix analysis to show that Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) can improve pulsar-timing constraints for some equations of state (EOSs), and next-generation detectors, such as the Cosmic Explorer and Einstein Telescope, will be able to improve those bounds for all eleven EOSs
Which are the most probable masses for the newly discovered asymmetric double-neutron stars (NSs) binary pulsar PSR J1913 þ 1102 [87], we find that Advanced LIGO (aLIGO), Cosmic Explorer (CE), and Einstein Telescope (ET) can detect its merger at 200 Mpc with ρ 1⁄4 10.6, 450, and 153, respectively, after averaging over pattern functions and assuming two detectors in each case
Summary
In general relativity (GR), gravity is mediated solely by a rank-2 tensor, namely, the spacetime metric gμν. Our results demonstrate that, depending on the parameters of binary systems and NS equations of state (EOSs), these two types of experiments can provide complementary bounds on scalar-tensor theories [10,11,12,20,21]. These results are especially timely as new instruments come online in the upcoming years in both fields [22,23]. V, we discuss the main results and implications of our findings and give perspectives for future observations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
