scholarly journals Discriminating strange star mergers from neutron star mergers by gravitational-wave measurements

2010 ◽  
Vol 81 (2) ◽  
Author(s):  
A. Bauswein ◽  
R. Oechslin ◽  
H.-T. Janka
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Strange Star ◽  
Wave Measurements

scholarly journals A scalable random forest regressor for combining neutron-star equation of state measurements: a case study with GW170817 and GW190425

2020 ◽  
Vol 499 (4) ◽  
pp. 5972-5977
Author(s):  
Francisco Hernandez Vivanco ◽  
Rory Smith ◽  
Eric Thrane ◽  
Paul D Lasky
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Learning Algorithm ◽  
Machine Learning Algorithm ◽  
Combine Data ◽  
Binary Neutron Star ◽  
Wave Measurements ◽  
Wave Observation

ABSTRACT Gravitational-wave observations of binary neutron star coalescences constrain the neutron-star equation of state by enabling measurement of the tidal deformation of each neutron star. This deformation is well approximated by the tidal deformability parameter Λ, which was constrained using the first binary neutron star gravitational-wave observation, GW170817. Now, with the measurement of the second binary neutron star, GW190425, we can combine different gravitational-wave measurements to obtain tighter constraints on the neutron-star equation of state. In this paper, we combine data from GW170817 and GW190425 to place constraints on the neutron-star equation of state. To facilitate this calculation, we derive interpolated marginalized likelihoods for each event using a machine learning algorithm. These likelihoods, which we make publicly available, allow for results from multiple gravitational-wave signals to be easily combined. Using these new data products, we find that the radius of a fiducial 1.4 M⊙ neutron star is constrained to $11.6^{+1.6}_{-0.9}$ km at 90 per cent confidence and the pressure at twice the nuclear saturation density is constrained to $3.1^{+3.1}_{-1.3}\times 10^{34}$ dyne cm−2 at 90 per cent confidence. Combining GW170817 and GW190425 produces constraints indistinguishable from GW170817 alone and is consistent with findings from other works.

scholarly journals Parameter estimation of a two-component neutron star model with spin wandering

2021 ◽  
Vol 502 (3) ◽  
pp. 3113-3127
Author(s):  
Patrick M Meyers ◽  
Andrew Melatos ◽  
Nicholas J O’Neill
Keyword(s):  
Neutron Star ◽  
Angular Velocity ◽  
Gravitational Wave ◽  
White Noise ◽  
Physical Parameters ◽  
Star Model ◽  
Wave Measurements ◽  
Two Component ◽  
Timing Data ◽  
Timing Noise

ABSTRACT It is an open challenge to estimate systematically the physical parameters of neutron star interiors from pulsar timing data while separating spin wandering intrinsic to the pulsar (achromatic timing noise) from measurement noise and chromatic timing noise (due to propagation effects). In this paper, we formulate the classic two-component, crust-superfluid model of neutron star interiors as a noise-driven, linear dynamical system and use a state-space-based expectation–maximization method to estimate the system parameters using gravitational-wave and electromagnetic timing data. Monte Carlo simulations show that we can accurately estimate all six parameters of the two-component model provided that electromagnetic measurements of the crust angular velocity and gravitational-wave measurements of the core angular velocity are both available. When only electromagnetic data are available, we can recover the overall relaxation time-scale, the ensemble-averaged spin-down rate, and the strength of the white-noise torque on the crust. However, the estimates of the secular torques on the two components and white-noise torque on the superfluid are biased significantly.

scholarly journals Comparing inclination-dependent analyses of kilonova transients

2021 ◽  
Vol 502 (2) ◽  
pp. 3057-3065
Author(s):  
J Heinzel ◽  
M W Coughlin ◽  
T Dietrich ◽  
M Bulla ◽  
S Antier ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Inclination Angle ◽  
Soft Constraints ◽  
Parameter Inference ◽  
Binary Neutron Star ◽  
Wave Measurements ◽  
Inclination Angles ◽  
Optical Transient

ABSTRACT The detection of the optical transient AT2017gfo proved that binary neutron star mergers are progenitors of kilonovae (KNe). Using a combination of numerical-relativity and radiative-transfer simulations, the community has developed sophisticated models for these transients for a wide portion of the expected parameter space. Using these simulations and surrogate models made from them, it has been possible to perform Bayesian inference of the observed signals to infer properties of the ejected matter. It has been pointed out that combining inclination constraints derived from the KN with gravitational-wave measurements increases the accuracy with which binary parameters can be estimated, in particular breaking the distance-inclination degeneracy from gravitational wave inference. To avoid bias from the unknown ejecta geometry, constraints on the inclination angle for AT2017gfo should be insensitive to the employed models. In this work, we compare different assumptions about the ejecta and radiative reprocesses used by the community and we investigate their impact on the parameter inference. While most inferred parameters agree, we find disagreement between posteriors for the inclination angle for different geometries that have been used in the current literature. According to our study, the inclusion of reprocessing of the photons between different ejecta types improves the modeling fits to AT2017gfo and, in some cases, affects the inferred constraints. Our study motivates the inclusion of large ∼ 1-mag uncertainties in the KN models employed for Bayesian analysis to capture yet unknown systematics, especially when inferring inclination angles, although smaller uncertainties seem appropriate to capture model systematics for other intrinsic parameters. We can use this method to impose soft constraints on the ejecta geometry of the KN AT2017gfo.

scholarly journals Waveform systematics in the gravitational-wave inference of tidal parameters and equation of state from binary neutron-star signals

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Rossella Gamba ◽  
Matteo Breschi ◽  
Sebastiano Bernuzzi ◽  
Michalis Agathos ◽  
Alessandro Nagar
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Binary Neutron Star

scholarly journals A Gravitational-Wave Perspective on Neutron-Star Seismology

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 97
Author(s):  
Nils Andersson
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Fundamental Mode ◽  
Compact Binaries

We provide a bird’s-eye view of neutron-star seismology, which aims to probe the extreme physics associated with these objects, in the context of gravitational-wave astronomy. Focussing on the fundamental mode of oscillation, which is an efficient gravitational-wave emitter, we consider the seismology aspects of a number of astrophysically relevant scenarios, ranging from transients (like pulsar glitches and magnetar flares), to the dynamics of tides in inspiralling compact binaries and the eventual merged object and instabilities acting in isolated, rapidly rotating, neutron stars. The aim is not to provide a thorough review, but rather to introduce (some of) the key ideas and highlight issues that need further attention.

scholarly journals Gravitational wave emission from a magnetically deformed non-barotropic neutron star

2011 ◽  
Vol 417 (3) ◽  
pp. 2288-2299 ◽  
Author(s):  
A. Mastrano ◽  
A. Melatos ◽  
A. Reisenegger ◽  
T. Akgün
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Wave Emission

scholarly journals Accelerated detection of the binary neutron star gravitational-wave background

2019 ◽  
Vol 100 (4) ◽  
Author(s):  
Francisco Hernandez Vivanco ◽  
Rory Smith ◽  
Eric Thrane ◽  
Paul D. Lasky
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Binary Neutron Star ◽  
Gravitational Wave Background

scholarly journals Quadrupole moments of rotating compact stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 536-536
Author(s):  
Martin Urbanec ◽  
John Miller ◽  
Zdenek Stuchlik
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Strange Star ◽  
Compact Stars ◽  
Quadrupole Moments ◽  
Strange Stars

AbstractWe present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.

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