Session H18: Nuclear Physics and Particle Physics with Gravitational Waves

Live

Recent results from the NICER collaboration provide direct measurements of the mass and radius $R$ of a neutron star PSR J0030+0451. We combine this with the measurement of mass-weighted tidal deformability $\tilde{\Lambda}$ extracted from the binary neutron star merger event GW170817 through gravitational waves to place bounds on various nuclear matter parameters. The latter parameters are obtained by expanding binding energy per nucleon with nucleon number density and isospin symmetry. We first construct correlations between $R$, $\tilde{\Lambda}$, and linear combinations of nuclear parameters. Assuming that these distributions are 3-dimensional Gaussian, we extract bounds on each nuclear parameter (such as the curvature of symmetry energy) by marginalizing over the uncertainties in the measurement of $R$ and $\tilde{\Lambda}$. We also comment on how these bounds change when we use radius measurements from other X-ray observations of neutron stars.   

Live

Astrophysical observations of neutron stars in binaries and in isolation can provide complimentary information about the dense-matter equation of state. We combine recent gravitational-wave, x-ray and radio observations of neutron stars to place joint constraints on the properties of supranuclear matter, modeling the uncertain equation of state with a nonparametric Gaussian process. We exploit (i) measurements of tidal deformability from binary inspirals detected by LIGO and Virgo, (ii) simultaneous mass and radius measurements obtained by NICER from surface hotspot emission, and (iii) lower bounds on the maximum neutron-star mass from surveys of massive pulsars. We also make projections for future constraints on the equation of state based on a simulated population of astrophysical observations.   

Live

Ultralight bosons can form clouds around rotating black holes if their Compton wavelength is comparable to the black hole size. The boson cloud spins down the black hole through a process called superradiance, lowering the black hole spin to a characteristic value. It has thus been suggested that spin measurements of the black holes detected by ground-based gravitational-wave detectors can be used to constrain the mass of ultralight bosons. Unfortunately, a measurement of the individual black hole spins is often uncertain, resulting in inconclusive results. Instead, we use hierarchical Bayesian inference to combine information from multiple gravitational-wave sources and obtain stronger constraints. We show that tens to hundreds of high signal-to-noise ratio gravitational-wave detections are enough to exclude (confirm) the existence of bosons in the $[10^{-13}, 3\times10^{-12}]$ eV mass range. The expected number of detections depends on the distribution of black hole spins at formation and on the mass of the boson. We then apply our method to the 10 binary black hole mergers detected by LIGO and Virgo in their first two observing runs, finding that we cannot draw statistically significant conclusion from the small number of sources.   

Live

Ultralight scalar boson particles, if they exist as theorized, could form clouds around rapidly rotating black holes. Such clouds are expected to emit continuous, quasimonochromatic gravitational waves that could be detected by ground-based detectors like LIGO and Virgo. Here we present the first constraints on the boson mass obtained from a gravitational-wave search directed at a known black hole in the nearby X-ray binary, Cygnus X-1, using data from Advanced LIGO's second observing run. Without finding evidence of gravitational-wave signals in this search, the constraints are derived for two scenarios with or without considering boson self-interactions. In this talk, we present a brief theoretical overview of the signal model and source properties, describe the search method and challenges, and show results from this analysis. Applications of this method to other sources in future observing runs will yield improved constraints and possibly a detection.   

Live

We present the first fully general relativistic dynamical simulations of Abelian Higgs cosmic strings using 3+1D numerical relativity. Focusing on cosmic string loops, we show that they collapse due to their tension and can either (i) unwind and disperse or (ii) form a black hole, depending on their tension $G\mu$ and initial radius. We show that these results can be predicted using an approximate formula derived using the hoop conjecture, and argue that it is independent of field interactions. We extract the gravitational waveform produced in the black hole formation case and show that it is dominated by the $l=2$ and $m=0$ mode. We also compute the total gravitational wave energy emitted during such a collapse, being $0.5\pm 0.2~ \%$ of the initial total cosmic string loop mass, for a string tension of $G\mu=1.6\times 10^{-2}$ and radius $R=100~M_{pl}^{-1}$. We use our results to put a bound on the production rate of planar cosmic strings loops as $N \leq 10^{-2}~\mathrm{Gpc}^{-3}~\mathrm{yr}^{-1}$.   

Measuring Tidal Deformability and Radii of Neutron Star Sources with Third Generation Gravitational Wave~Detector Networks

Third generation gravitational wave detectors such as the Einstein Telescope and Cosmic Explorer could be the newest members of an ever-expanding network of current and planned ground-based detectors across the globe. With each detector addition, a more sensitive network is created with improved capabilities. In this presentation, we explore how well current and proposed detector network configurations constrain the tidal deformability and radii of neutron star sources and how third generation of detectors will improve these. Specifically, we focus on how the capability of possible 3G detector networks changes for different arm lengths and bandwidths of Cosmic Explorer.   

On Demand

Observations of the properties of multiple coalescing neutron stars will simultaneously provide insight into the neutron star (NS) mass and spin distribution, the NS merger rate, and the nuclear equation of state. Gravitational wave observations demonstrate that merging compact objects arise from a diverse population. We show how to combine all information obtained from gravitational wave measurements into a joint constraint on the NS merger rate, the distribution of NS properties, and the nuclear equation of state (EOS). We illustrate the importance of joint modeling with a concrete example, illustrating how biased mass distribution inferences can significantly impact the recovered equation of state, even in the small-N limit. We discuss how to incorporate recent results into a revised constraint on the EOS.   

Constraining properties of dark matter candidates from gravitational-wave observations

The rate of binary neutron star mergers determined by gravitational-wave observations is so large that we can expect the next generation of ground-based detectors to observe up to millions of mergers each year. If progenitor binaries live long enough then certain dark matter particles, depending on their mass and interaction cross section, could accumulate in neutron star cores, collapse, and form mini black holes that grow during the binary’s lifetime. Eventually, accretion of such dark matter particles could lead to the implosion of one or both the companion neutron stars. Thus the observed universe might contain three distinct populations of compact binaries in the mass range $\sim \mbox{1--3}\, M_\odot$ - one containing only neutron stars, a second population of only black holes, and a third consisting of a neutron star and black hole. In this talk we explore the capability of future gravitational-wave detectors such as the proposed US Cosmic Explorer and the European Einstein Telescope, to discriminate the different populations by measuring the tidal deformability of the companion stars. The relative rates of the different populations constrains the properties of dark matter particles.   

Not Participating

We perform joint analysis of NICER observation of PSR J0030+0451 and LIGO observation of GW170817. The constrains on equation of state(EOS) is calculated with different EOS parameterizations. We discover that natural prior with uniform EOS parameter generally have more weights on large neutron star radius. Thus, we suggest a prior with flat radius $R_{1.4}$, allowing consistent result from different EOS parameterizations. Instead of taking uniform mass prior while evaluate likelihood, we use maximal likelihood in mass for NICER and in mass ratio for LIGO in order to reduce bias of dM/dR.