abstract stringlengths 3 192k | title stringlengths 4 857 |
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in this letter, we uncover a universal relaxation mechanism of pinned density waves, combining gauge-gravity duality and effective field theory techniques. upon breaking translations spontaneously, new gapless collective modes emerge, the nambu-goldstone bosons of broken translations. when translations are also weakly broken (e.g., by disorder or lattice effects), these phonons are pinned with a mass m and damped at a rate ω , which we explicitly compute. this contribution to ω is distinct from that of topological defects. we show that ω ≃g m2ξ , where g is the shear modulus and ξ is related to a diffusivity of the purely spontaneous state. this result follows from the smallness of the bulk and shear moduli, as would be the case in a phase with fluctuating translational order. at low temperatures, the collective modes relax quickly into the heat current, so that late time transport is dominated by the thermal diffusivity. in this regime, the resistivity in our model is linear in temperature and the ac conductivity displays a significant rearranging of the degrees of freedom, as spectral weight is shifted from an off-axis, pinning peak to a drude-like peak. these results could shed light on transport properties in cuprate high tc superconductors, where quantum critical behavior and translational order occur over large parts of the phase diagram and transport shows qualitatively similar features. | universal relaxation in a holographic metallic density wave phase |
the advanced ligo and advanced virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. a short gamma-ray burst (grb) that followed the merger of this binary was also recorded by the fermi gamma-ray burst monitor (fermi-gbm), and the anti-coincidence shield for the spectrometer for the international gamma-ray astrophysics laboratory (integral), indicating particle acceleration by the source. the precise location of the event was determined by optical detections of emission following the merger. we searched for high-energy neutrinos from the merger in the gev-eev energy range using the antares, icecube, and pierre auger observatories. no neutrinos directionally coincident with the source were detected within ±500 s around the merger time. additionally, no mev neutrino burst signal was detected coincident with the merger. we further carried out an extended search in the direction of the source for high-energy neutrinos within the 14 day period following the merger, but found no evidence of emission. we used these results to probe dissipation mechanisms in relativistic outflows driven by the binary neutron star merger. the non-detection is consistent with model predictions of short grbs observed at a large off-axis angle. | search for high-energy neutrinos from binary neutron star merger gw170817 with antares, icecube, and the pierre auger observatory |
the atmosphere of mars is thin, although rich in dust aerosols, and covers a dry surface. as such, mars provides an opportunity to expand our knowledge of atmospheres beyond that attainable from the atmosphere of the earth. the insight (interior exploration using seismic investigations, geodesy and heat transport) lander is measuring mars's atmosphere with unprecedented continuity, accuracy and sampling frequency. here we show that insight unveils new atmospheric phenomena at mars, especially in the higher-frequency range, and extends our understanding of mars's meteorology at all scales. insight is uniquely sensitive to large-scale and regional weather and obtained detailed in situ coverage of a regional dust storm on mars. images have enabled high-altitude wind speeds to be measured and revealed airglow—faint emissions produced by photochemical reactions—in the middle atmosphere. insight observations show a paradox of aeolian science on mars: despite having the largest recorded martian vortex activity and dust-devil tracks close to the lander, no visible dust devils have been seen. meteorological measurements have produced a catalogue of atmospheric gravity waves, which included bores (soliton-like waves). from these measurements, we have discovered martian infrasound and unexpected similarities between atmospheric turbulence on earth and mars. we suggest that the observations of mars's atmosphere by insight will be key for prediction capabilities and future exploration. | the atmosphere of mars as observed by insight |
we introduce a model for matters-genesis in which both the baryonic and dark matter asymmetries originate from a first-order phase transition in a dark sector with an $su(3)\times su(2)\times u(1)$ gauge group and minimal matter content. in the simplest scenario, we predict that dark matter is a dark antineutron with mass either $m_{\bar{n}} = 1.36$ gev or $m_{\bar{n}} = 1.63$ gev. alternatively, dark matter may be comprised of equal numbers of dark antiprotons and pions. this model, in either scenario, is highly discoverable through both dark matter direct detection and dark photon search experiments. the strong dark matter self interactions may ameliorate small-scale structure problems, while the strongly first-order phase transition may be confirmed at future gravitational wave observatories. | asymmetric matters from a dark first-order phase transition |
we show that it is possible to use gravitational wave detectors to observe the occurrence of a first order phase transition in pati-salam extensions of the standard model. we show that the peak frequency of the expected gravitational wave signals ranges within 0.1-10 hz. we find amusing that the next generation of gravity waves detectors are able to explore time-honored extensions of the standard model occurring at energy scales inaccessible by present and future particle physics accelerators. | gravitational waves from pati-salam dynamics |
we propose a new scenario of leptogenesis, which is triggered by a first-order phase transition (fopt). the right-handed neutrinos (rhns) are massless in the old vacuum, while they acquire a mass in the new vacuum bubbles, and the mass gap is huge compared with the fopt temperature. the ultra-relativistic bubble walls sweep the rhns into the bubbles, where the rhns experience fast decay and generate the lepton asymmetry, which is further converted to the baryon asymmetry of the universe (bau). since the rhns are out of equilibrium inside the bubble, the generated bau does not suffer from the thermal bath washout. we first discuss the general feature of such a fopt leptogenesis mechanism, and then realize it in an extended b − l model. the gravitational waves from u(1)b−l breaking could be detected at the future interferometers. | leptogenesis triggered by a first-order phase transition |
motivated by the recent detection of the gravitational wave signal emitted by a binary neutron star merger, we analyse the possible impact of dark matter on such signals. we show that dark matter cores in merging neutron stars may yield an observable supplementary peak in the gravitational wave power spectral density following the merger, which could be distinguished from the features produced by the neutron components. | search for dark matter effects on gravitational signals from neutron star mergers |
high-power laser delivery with near-diffraction-limited beam quality is typically limited to tens of metres distances by nonlinearity-induced spectral broadening inside the glass core of delivery fibres. anti-resonant hollow-core fibres offer not only orders-of-magnitude lower nonlinearity but also loss and modal purity comparable to conventional beam-delivery fibres. using a single-mode hollow-core nested anti-resonant nodeless fibre with 0.74 db km−1 loss, we demonstrate the delivery of 1 kw of near-diffraction-limited continuous-wave laser light over a 1 km distance, with a total throughput efficiency of ~80%. from simulations, a further improvement in transmitted power or length of more than one order of magnitude should be possible in such air-filled fibres, and considerably more if the core is evacuated. this paves the way to multi-kilometre, kilowatt-scale power delivery that is potentially useful not only for future manufacturing and subsurface drilling but also for new scientific possibilities in sensing, particle acceleration and gravitational wave detection. | kilowatt-average-power single-mode laser light transmission over kilometre-scale hollow-core fibre |
we present a comprehensive optical and near-infrared census of the fields of 90 short gamma-ray bursts (grbs) discovered in 2005-2021, constituting all short grbs for which host galaxy associations are feasible (≈60% of the total swift short grb population). we contribute 274 new multi-band imaging observations across 58 distinct grbs and 26 spectra of their host galaxies. supplemented by literature and archival survey data, the catalog contains 542 photometric and 42 spectroscopic data sets. the photometric catalog reaches 3σ depths of ≳24-27 mag and ≳23-26 mag for the optical and near-infrared bands, respectively. we identify host galaxies for 84 bursts, in which the most robust associations make up 56% (50/90) of events, while only a small fraction, 6.7%, have inconclusive host associations. based on new spectroscopy, we determine 18 host spectroscopic redshifts with a range of z ≈ 0.15-1.5 and find that ≈23%-41% of swift short grbs originate from z > 1. we also present the galactocentric offset catalog for 84 short grbs. taking into account the large range of individual measurement uncertainties, we find a median of projected offset of ≈7.7 kpc, for which the bursts with the most robust associations have a smaller median of ≈4.8 kpc. our catalog captures more high-redshift and low-luminosity hosts, and more highly offset bursts than previously found, thereby diversifying the population of known short grb hosts and properties. in terms of locations and host luminosities, the populations of short grbs with and without detectable extended emission are statistically indistinguishable. this suggests that they arise from the same progenitors, or from multiple progenitors, which form and evolve in similar environments. all of the data products are available on the broadband repository for investigating gamma-ray burst host traits website. | short grb host galaxies. i. photometric and spectroscopic catalogs, host associations, and galactocentric offsets |
classical limit of multiple soft graviton theorem can be used to compute the angular power spectrum of long wavelength gravitational radiation in classical scattering provided the total energy carried away by the radiation is small compared to the energies of the scatterers. we could ensure this either by taking the limit in which the impact parameter is large compared to the schwarzschild radii of the scatterers, or by taking the probe limit where one object (the probe) has mass much smaller than the other object (the scatterer). we compute the results to subsubleading order in soft momentum and test them using explicit examples involving classical scattering. our analysis also generalizes to the case where there are multiple objects involved in the scattering and the objects exchange mass, fragment or fuse into each other during the scattering. a similar analysis can be carried out for soft photons to subleading order, reproducing standard textbook results. we also discuss the modification of soft expansion in four dimensions beyond the leading order due to infrared divergences. | gravity waves from soft theorem in general dimensions |
advanced methods for computing perturbative, quantum-gravitational scattering amplitudes show great promise for improving our knowledge of classical gravitational dynamics. this is especially true in the weak-field and arbitrary-speed (post-minkowskian, pm) regime, where the conservative dynamics at 3pm order has been recently determined for the first time, via an amplitude calculation. such pm results are most relevantly applicable to relativistic scattering (unbound orbits), while bound/inspiraling binary systems, the most frequent sources of gravitational waves for the ligo and virgo detectors, are most suitably modeled by the weak-field and slow-motion (post-newtonian, pn) approximation. nonetheless, it has been suggested that pm results can independently lead to improved modeling of bound binary dynamics, especially when taken as inputs for effective-one-body (eob) models of inspiraling binaries. here, we initiate a quantitative study of this possibility, by comparing pm, eob and pn predictions for the binding energy of a two-body system on a quasicircular inspiraling orbit against results of numerical relativity (nr) simulations. the binding energy is one of the two central ingredients (the other being the gravitational-wave energy flux) that enters the computation of gravitational waveforms employed by ligo and virgo detectors, and for (quasi)circular orbits it provides an accurate diagnostic of the conservative sector of a model. we find that, whereas 3pm results do improve the agreement with nr with respect to 2pm (especially when used in the eob framework), it is crucial to push pm calculations at higher orders if one wants to achieve better performances than current waveform models used for ligo/virgo data analysis. | energetics of two-body hamiltonians in post-minkowskian gravity |
we present ${\tt nrpmw}$, an analytical model of gravitational-waves from neutron star merger remnants informed using 618 numerical relativity (nr) simulations. ${\tt nrpmw}$ is designed in the frequency domain using a combination of complex gaussian wavelets. the wavelet's parameters are calibrated to equations of state (eos) insensitive relations from nr data. the nr simulations are computed with 21 eos (7 of which are finite-temperature microphysical models, and 3 of which contain quark phase transitions or hyperonic degrees of freedom) and span total binary masses $m\in[2.4,3.4]~{\rm m}_\odot$, mass ratios up to $q=2$, and (nonprecessing) dimensionless spins magnitudes up to ${0.2}$. the theoretical uncertainties of the eos-insensitive relations are incorporated in ${\tt nrpmw}$ using recalibration parameters that enhance the flexibility and accuracy of the model. ${\tt nrpmw}$ is nr-faithful with fitting factors ${\gtrsim}0.9$ computed on an independent validation set of 102 simulations. | kilohertz gravitational waves from binary neutron star mergers: numerical-relativity informed postmerger model |
gravitational waves emitted from the coalescence of neutron star binaries open a new window to probe matter and fundamental physics in unexplored, extreme regimes. to extract information about the supranuclear matter inside neutron stars and the properties of the compact binary systems, robust theoretical prescriptions are required. we give an overview about general features of the dynamics and the gravitational wave signal during the binary neutron star coalescence. we briefly describe existing analytical and numerical approaches to investigate the highly dynamical, strong-field region during the merger. we review existing waveform approximants and discuss properties and possible advantages and shortcomings of individual waveform models, and their application for real gravitational-wave data analysis. | interpreting binary neutron star mergers: describing the binary neutron star dynamics, modelling gravitational waveforms, and analyzing detections |
we examine which information on the early cosmological history can be extracted from the potential measurement by third-generation gravitational-wave observatories of a stochastic gravitational wave background (sgwb) produced by cosmic strings. we consider a variety of cosmological scenarios breaking the scale-invariant properties of the spectrum, such as early long matter or kination eras, short intermediate matter and inflation periods inside a radiation era, and their specific signatures on the sgwb . this requires to go beyond the usually-assumed scaling regime, to take into account the transient effects during the change of equation of state of the universe. we compute the time evolution of the string network parameters and thus the loop-production efficiency during the transient regime, and derive the corresponding shift in the turning-point frequency. we consider the impact of particle production on the gravitational-wave emission by loops. we estimate the reach of future interferometers lisa, bbo, decigo, et and ce and radio telescope ska to probe the new physics energy scale at which the universe has experienced changes in its expansion history. we find that a given interferometer may be sensitive to very different energy scales, depending on the nature and duration of the non-standard era, and the value of the string tension. it is fascinating that by exploiting the data from different gw observatories associated with distinct frequency bands, we may be able to reconstruct the full spectrum and therefore extract the values of fundamental physics parameters. | beyond the standard models with cosmic strings |
parity solutions to the strong cp problem are a compelling alternative to approaches based on peccei-quinn symmetry, particularly given the expected violation of global symmetries in a theory of quantum gravity. the most natural of these solutions break parity at a low scale, giving rise to a host of experimentally accessible signals. we assess the status of the simplest parity-based solution in light of lhc data and flavor constraints, highlighting the prospects for near-future tests at colliders, tabletop experiments, and gravitational wave observatories. the origin of parity breaking and associated gravitational effects play crucial roles, providing new avenues for discovery through edms and gravity waves. these experimental opportunities underline the promise of generalized parity, rather than peccei-quinn symmetry, as a robust and testable solution to the strong cp problem. | p not pq |
we present a data analysis methodology for a model-independent reconstruction of the spectral shape of a stochastic gravitational wave background with lisa. we improve a previously proposed reconstruction algorithm that relied on a single time-delay-interferometry (tdi) channel by including a complete set of tdi channels. as in the earlier work, we assume an idealized equilateral configuration. we test the improved algorithm with a number of case studies, including reconstruction in the presence of two different astrophysical foreground signals. we find that including additional channels helps in different ways: it reduces the uncertainties on the reconstruction; it makes the global likelihood maximization less prone to falling into local extrema; and it efficiently breaks degeneracies between the signal and the instrumental noise. | improved reconstruction of a stochastic gravitational wave background with lisa |
we calculate gravitational wave power spectra from first order early universe phase transitions using the sound shell model. the model predicts that the power spectrum depends on the mean bubble separation, the phase transition strength, the phase boundary speed, with the overall frequency scale set by the nucleation temperature. there is also a dependence on the time evolution of the bubble nucleation rate. the gravitational wave peak power and frequency are in good agreement with published numerical simulations, where bubbles are nucleated simultaneously. agreement is particularly good for detonations, but the total power for deflagrations is predicted higher than numerical simulations show, indicating refinement of the model of the transfer of energy to the fluid is needed for accurate computations. we show how the time-dependence of the bubble nucleation rate affects the shape of the power spectrum: an exponentially rising nucleation rate produces higher amplitude gravitational waves at a longer wavelength than simultaneous nucleation. we present an improved fit for the predicted gravitational wave power spectrum in the form of a double broken power law, where the two breaks in the slope happen at wavenumber corresponding to the mean bubble separation and the thickness of the fluid shell surrounding the expanding bubbles, which in turn is related to the difference of the phase boundary speed from the speed of sound. | gravitational waves from first order cosmological phase transitions in the sound shell model |
gravitational-wave echoes in the postmerger signal of a binary coalescence are predicted in various scenarios, including near-horizon quantum structures, exotic states of matter in ultracompact stars, and certain deviations from general relativity. the amplitude and frequency of each echo is modulated by the photon-sphere barrier of the remnant, which acts as a spin- and frequency-dependent high-pass filter, decreasing the frequency content of each subsequent echo. furthermore, a major fraction of the energy of the echo signal is contained in low-frequency resonances corresponding to the quasinormal modes of the remnant. motivated by these features, in this work we provide an analytical gravitational-wave template in the low-frequency approximation describing the postmerger ringdown and the echo signal of a spinning ultracompact object. besides the standard ringdown parameters, the template is parametrized in terms of only two physical quantities: the reflectivity coefficient and the compactness of the remnant. we discuss novel effects related to the spin and to the complex reflectivity, such as a more involved modulation of subsequent echoes, the mixing of two polarizations, and the ergoregion instability in the case of perfectly reflecting spinning remnants. finally, we compute the errors in the estimation of the template parameters with current and future gravitational-wave detectors using a fisher matrix framework. our analysis suggests that models with almost perfect reflectivity can be excluded/detected with current instruments, whereas probing values of the reflectivity smaller than 80% at the 3 σ confidence level requires future detectors (einstein telescope, cosmic explorer, lisa). the template developed in this work can easily be implemented to perform a matched-filter based search for echoes and to constrain models of exotic compact objects. | analytical model for gravitational-wave echoes from spinning remnants |
a gauge-invariant framework for computing bubble nucleation rates at finite temperature in the presence of radiative barriers was presented and advocated for model-building and phenomenological studies in an accompanying article [1]. here, we detail this computation using the abelian higgs model as an illustrative example. subsequently, we recast this approach in the dimensionally-reduced high-temperature effective field theory for nucleation. this allows for including several higher order thermal resummations and furthermore delineate clearly the approach's limits of validity. this approach provides for robust perturbative treatments of bubble nucleation during possible first-order cosmic phase transitions, with implications for electroweak baryogenesis and production of a stochastic gravitational wave background. furthermore, it yields a sound comparison between results of perturbative and non-perturbative computations. | computing the gauge-invariant bubble nucleation rate in finite temperature effective field theory |
the joint detection of the gravitational wave gw170817, of the short γ-ray burst grb170817a and of the kilonova at2017gfo, generated by the the binary neutron star (ns) merger observed on 2017 august 17, is a milestone in multimessenger astronomy and provides new constraints on the ns equation of state. we perform bayesian inference and model selection on at2017gfo using semi-analytical, multicomponents models that also account for non-spherical ejecta. observational data favour anisotropic geometries to spherically symmetric profiles, with a log-bayes' factor of ~104, and favour multicomponent models against single-component ones. the best-fitting model is an anisotropic three-component composed of dynamical ejecta plus neutrino and viscous winds. using the dynamical ejecta parameters inferred from the best-fitting model and numerical-relativity relations connecting the ejecta properties to the binary properties, we constrain the binary mass ratio to q < 1.54 and the reduced tidal parameter to $120\lt \tilde{\lambda }\lt 1110$. finally, we combine the predictions from at2017gfo with those from gw170817, constraining the radius of a ns of 1.4 m⊙ to 12.2 ± 0.5 km (1σ level). this prediction could be further strengthened by improving kilonova models with numerical-relativity information. | at2017gfo: bayesian inference and model selection of multicomponent kilonovae and constraints on the neutron star equation of state |
in this paper, we revisit the estimation of the spectrum of primordial gravitational waves originated from inflation, particularly focusing on the effect of thermodynamics in the standard model of particle physics. by collecting recent results of perturbative and non-perturbative analysis of thermodynamic quantities in the standard model, we obtain the effective degrees of freedom including the corrections due to non-trivial interaction properties of particles in the standard model for a wide temperature interval. the impact of such corrections on the spectrum of primordial gravitational waves as well as the damping effect due to free-streaming particles is investigated by numerically solving the evolution equation of tensor perturbations in the expanding universe. it is shown that the reevaluation of the effects of free-streaming photons and neutrinos gives rise to some additional damping features overlooked in previous studies. we also observe that the continuous nature of the qcd crossover results in a smooth spectrum for modes that reenter the horizon at around the epoch of the qcd phase transition. furthermore, we explicitly show that the values of the effective degrees of freedom remain smaller than the commonly used value 106.75 even at temperature much higher than the critical temperature of the electroweak crossover, and that the amplitude of primordial gravitational waves at a frequency range relevant to direct detection experiments becomes script o(1) % larger than previous estimates that do not include such corrections. this effect can be relevant to future high-sensitivity gravitational wave experiments such as ultimate decigo. our results on the temperature evolution of the effective degrees of freedom are made available as tabulated data and fitting functions, which can also be used in the analysis of other cosmological relics. | primordial gravitational waves, precisely: the role of thermodynamics in the standard model |
the post-minkowskian expansion of einstein's general theory of relativity has received much attention in recent years due to the possibility of harnessing the computational power of modern amplitude calculations in such a classical context. in this brief review, we focus on the post-minkowskian expansion as applied to the two-body problem in general relativity without spin, and we describe how relativistic quantum field theory can be used to greatly simplify analytical calculations based on the einstein-hilbert action. subtleties related to the extraction of classical physics from such quantum mechanical calculations highlight the care which must be taken when both positive and negative powers of planck's constant are at play. in the process of obtaining classical results in both einstein gravity and supergravity, one learns new aspects of quantum field theory that are obscured when using units in which planck's constant is set to unity. the scattering amplitude approach provides a self-contained framework for deriving the two-body scattering valid in all regimes of energy. there is hope that the full impact of amplitude computations in this field may significantly alter the way in which gravitational wave predictions will advance in the coming years. | the sagex review on scattering amplitudes chapter 13: post-minkowskian expansion from scattering amplitudes |
the laser ranging interferometer (lri) instrument on the gravity recovery and climate experiment (grace) follow-on mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations. the lri has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of 1 nm /√{hz } at fourier frequencies above 100 mhz. | in-orbit performance of the grace follow-on laser ranging interferometer |
we discuss theories of gravity with independent metric (or frame field) and connection, from the point of view of effective field theory. we count the parity-even lagrangian terms of dimension up to four and give explicit bases for the independent terms that contribute to the two-point function. we then give the decomposition of the linearized action on a complete basis of spin projectors and consider various subclasses of metric-affine gravity (mag) theories. we show that teleparallel theories can be dynamically equivalent to any metric theory of gravity and give the particle content of those whose lagrangian contains only dimension-two terms. we point out the existence of a class of mags whose equations of motion do not admit propagating degrees of freedoms. finally, we construct simple mags that contain only a massless graviton and a state of spin/parity 2- or 3-. as a side result, we write the relativistic wave equation for a spin/parity 2- state. | metric-affine gravity as an effective field theory |
we study the gravitational waves (gws) spectrum produced during the electroweak phase transition in a scale-invariant extension of the standard model (sm), enlarged by a dark u (1) d gauge symmetry. this symmetry incorporates a vector dark matter (dm) candidate and a scalar field (scalon). because of scale invariance, the model has only two independent parameters and for the parameter space constrained by dm relic density, strongly first-order electroweak phase transition can take place. in this model, for a narrow part of the parameter space, dm-nucleon cross section is below the neutrino-floor limit, and therefore, it cannot be probed by the future direct detection experiments. however, for a benchmark point from this narrow region, we show the amplitude and frequency of phase transition gw spectrum fall within the observational window of space-based gw detectors such as elisa. | gravitational waves from scale-invariant vector dark matter model: probing below the neutrino-floor |
despite the tremendous success of general relativity so far, modified theories of gravity have received increased attention lately, motivated from both theoretical and observational aspects. in particular, gravitational wave observations opened new possibilities for testing the viability of such theories in the dynamical and strong-field regime. one could test each modified theory of gravity against observed data one at a time, though perhaps a more efficient approach would be to first probe gravity in a theory-agnostic way and map such information to that on specific theories afterward. one example of such model-independent tests of gravity with gravitational waves is the parametrized post-einsteinian formalism, in which one introduces generic parameters in the amplitude and phase that capture non-einsteinian effects. in this paper, we derive gravitational waveforms from inspiraling compact binaries in various modified theories of gravity that violate at least one fundamental pillar in general relativity, such as the strong equivalence principle, lorentz and parity invariance, and commutativity of spacetime. we achieve this by first deriving relations between corrections to the waveform amplitude/phase and those to the frequency evolution and kepler's third law, since the latter two have already been (or can easily be) derived in several example modified theories of gravity. in particular, such an analysis allows us to derive corrections to the waveform amplitude, which extends many of previous works that focused on deriving phase corrections only. moreover, we derive modified gravitational waveforms in theories with a varying gravitational constant. in particular, we extend the previous work by introducing two different gravitational constants (the conservative one entering in the binding energy and the dissipative one entering in the gravitational wave luminosity) and allowing masses of binary constituents to also vary with time. we also correct some errors in the previous literature. our results can be used to improve current analyses of testing general relativity with available gravitational wave data as well as to achieve new projected constraints on various modified theories of gravity with future gravitational wave observations. | parametrized post-einsteinian gravitational waveforms in various modified theories of gravity |
the stochastic gravitational wave background (sgwb) offers a new opportunity to observe signals of primordial features from inflationary models. we study their detectability with future space-based gravitational waves experiments, focusing our analysis on the frequency range of the lisa mission. we compute gravitational wave spectra from primordial features by exploring the parameter space of a two-field inflation model capable of generating different classes of features. fine-tuning in scales and amplitudes is necessary for these signals to fall in the observational windows. in some cases the scalar power spectrum can significantly exceed the ns=5 limit in single-field inflation and grow as fast as ns=9.1. once they show up, several classes of frequency-dependent oscillatory signals, characteristic of different underlying inflationary physics, may be distinguished and the sgwb provides a window on dynamics of the primordial universe independent of cosmic microwave background and large-scale structure. to connect with future experimental data, we discuss two approaches of how the results may be applied to data analyses. first, we discuss the possibility of reconstructing the signal with lisa, which requires a high signal-to-noise ratio. the second more sensitive approach is to apply templates representing the spectra as estimators. for the latter purpose, we construct templates that can accurately capture the spectral features of several classes of feature signals and compare them with the sgwb produced by other physical mechanisms. | probing primordial features with the stochastic gravitational wave background |
we describe updates and improvements to the bayeswave gravitational wave transient analysis pipeline, and provide examples of how the algorithm is used to analyze data from ground-based gravitational wave detectors. bayeswave models gravitational wave signals in a morphology-independent manner through a sum of frame functions, such as morlet-gabor wavelets or chirplets. bayeswave models the instrument noise using a combination of a parametrized gaussian noise component and nonstationary and non-gaussian noise transients. both the signal model and noise model employ trans-dimensional sampling, with the complexity of the model adapting to the requirements of the data. the flexibility of the algorithm makes it suitable for a variety of analyses, including reconstructing generic unmodeled signals; cross-checks against modeled analyses for compact binaries; as well as separating coherent signals from incoherent instrumental noise transients (glitches). the bayeswave model has been extended to account for gravitational wave signals with generic polarization content and the simultaneous presence of signals and glitches in the data. we describe updates in the bayeswave prior distributions, sampling proposals, and burn-in stage that provide significantly improved sampling efficiency. we present standard review checks indicating the robustness and convergence of the bayeswave trans-dimensional sampler. | bayeswave analysis pipeline in the era of gravitational wave observations |
there is a host of alternative theories of gravitation in the literature, among them the f (r ,t ) and f (r ,tϕ) theories recently elaborated by harko et al. in these theories, r , t and tϕ are respectively the ricci scalar and the traces of the energy-momentum tensors of matter and of a scalar field. there is already in the literature a series of studies of different forms of the f (r ,t ) and f (r ,tϕ) functions as well as their cosmological consequences. however, there have been no studies so far related to gravitational waves. here we consider such an issue, in particular, studying the putative extra polarization modes that can appear in the scope of such theories. different functional forms of f (r ,tϕ) are considered and the gravitational waveforms are found for the extra polarization modes in the cases in which they are present. | gravitational waves in f (r ,t ) and f (r ,tϕ) theories of gravity |
a number of recent works have highlighted that it is possible to express the properties of general-relativistic stellar equilibrium configurations in terms of functions that do not depend on the specific equation of state employed to describe matter at nuclear densities. these functions are normally referred to as `universal relations' and have been found to apply, within limits, both to static or stationary isolated stars, as well as to fully dynamical and merging binary systems. further extending the idea that universal relations can be valid also away from stability, we show that a universal relation is exhibited also by equilibrium solutions that are not stable. in particular, the mass of rotating configurations on the turning-point line shows a universal behaviour when expressed in terms of the normalized keplerian angular momentum. in turn, this allows us to compute the maximum mass allowed by uniform rotation, mmax, simply in terms of the maximum mass of the non-rotating configuration, m_{_tov}, finding that m_max ≃ (1.203 ± 0.022) m_{_tov} for all the equations of state we have considered. we further introduce an improvement to previously published universal relations by lattimer & schutz between the dimensionless moment of inertia and the stellar compactness, which could provide an accurate tool to constrain the equation of state of nuclear matter when measurements of the moment of inertia become available. | maximum mass, moment of inertia and compactness of relativistic stars |
we pave the way for future gravitational-wave detection experiments, such as the big bang observer and decigo, to constraint dark sectors made of s u (n ) yang-mills confined theories. we go beyond the state-of-the-art by combining first principle lattice results and effective field theory approaches to infer essential information about the nonperturbative dark deconfinement phase transition driving the generation of gravitational-waves in the early universe, such as the order, duration and energy budget of the phase transition which are essential in establishing the strength of the resulting gravitational-wave signal. | testing the dark su(n) yang-mills theory confined landscape: from the lattice to gravitational waves |
we present observations of the optical afterglow of grb 170817a, made by the hubble space telescope, between 2018 february and august, up to one year after the neutron star merger gw170817. the afterglow shows a rapid decline beyond 170 days, and confirms the jet origin for the observed outflow, in contrast to more slowly declining expectations for “failed-jet” scenarios. we show here that the broadband (radio, optical, x-ray) afterglow is consistent with a structured outflow where an ultra-relativistic jet, with a lorentz factor of γ ≳ 100, forms a narrow core (∼5°) and is surrounded by a wider angular component that extends to ∼15°, which is itself relativistic (γ ≳ 5). for a two-component model of this structure, the late-time optical decline, where f ∝ t -α , is α = 2.20 ± 0.18, and for a gaussian structure the decline is α = 2.45 ± 0.23. we find the gaussian model to be consistent with both the early ∼10 days and late ≳290 days data. the agreement of the optical light curve with the evolution of the broadband spectral energy distribution, and its continued decline, indicates that the optical flux is arising primarily from the afterglow and not any underlying host system. this provides the deepest limits on any host stellar cluster with a luminosity ≲4000 l ⊙ (m f606w ≳ -4.3). | the optical afterglow of gw170817 at one year post-merger |
these lecture notes bridge a gap between introductory quantum field theory (qft) courses and state-of-the-art research in scattering amplitudes. they cover the path from basic definitions of qft to amplitudes relevant for processes in the standard model of particle physics. the book begins with a concise yet self-contained introduction into qft, including perturbative quantum gravity. it then presents modern methods for calculating scattering amplitudes, focusing on tree-level amplitudes, loop-level integrands and loop-integration techniques. these methods help reveal intriguing relations between gauge and gravity amplitudes, and are of increasing importance for obtaining high-precision predictions for collider experiments, such as those at cern's large hadron collider, as well as for foundational mathematical physics studies in qft, including recent applications to gravitational wave physics. these course-tested lecture notes include numerous exercises with detailed solutions. requiring only minimal knowledge of qft, they are well-suited for msc and phd students as a preparation for research projects in theoretical particle physics. they can be used as a one-semester graduate level course, or as a self-study guide for researchers interested in fundamental aspects of qft. supplementary material, mathematica notebooks, corrections and further information are provided and maintained at the dedicated website https://scattering-amplitudes.mpp.mpg.de/scattering-amplitudes-in-qft/ . | scattering amplitudes in quantum field theory |
we point out that there are only three polarizations for gravitational waves in f (r ) gravity, and the polarization due to the massive scalar mode is a mix of the pure longitudinal and transverse breathing polarization. the classification of the six polarizations by the newman-penrose quantities is based on weak, plane and null gravitational waves, so it is not applicable to the massive mode. | polarizations of gravitational waves in f (r ) gravity |
we develop a nonparametric method for inferring the universal neutron star (ns) equation of state (eos) from gravitational wave (gw) observations. many different possible realizations of the eos are generated with a gaussian process conditioned on a set of nuclear-theoretic models. these synthetic eoss are causal and thermodynamically stable by construction, span a broad region of the pressure-density plane, and can be selected to satisfy astrophysical constraints on the ns mass. associating every synthetic eos with a pair of component masses m1 ,2 and calculating the corresponding tidal deformabilities λ1 ,2, we perform monte carlo integration over the gw likelihood for m1 ,2 and λ1 ,2 to directly infer a posterior process for the ns eos. we first demonstrate that the method can accurately recover the properties of an injected gw signal, and subsequently use it to analyze data from gw170817, finding a canonical deformability of λ1.4=16 0-113+448 and p (2 ρnuc)=1.3 5-1.2+1.8×1034 dyn /cm2 for the pressure at twice the nuclear saturation density at 90% confidence, in agreement with previous studies, when assuming a loose eos prior. with a prior more tightly constrained to resemble the theoretical eos models, we recover λ1.4=55 6-172+163 and p (2 ρnuc)=4.7 3-2.5+1.4×1034 dyn /cm2 . we further infer the maximum ns mass supported by the eos to be mmax=2.0 9-0.16+0.37 (2.0 4-0.002+0.22) m⊙ with the loose (tight) prior. the bayes factor between the two priors is bia≃1.12 , suggesting that neither is strongly preferred by the data and that constraints on the eos from gw170817 alone may be sensitive to the choice of prior. | nonparametric inference of the neutron star equation of state from gravitational wave observations |
momentum transport is anomalous in chiral p +i p superfluids and superconductors in the presence of textures and superflow. using the gradient expansion of the semiclassical approximation, we show how gauge and galilean symmetries induce an emergent curved spacetime with torsion and curvature for the quasirelativistic low-energy majorana-weyl quasiparticles. we explicitly show the emergence of the spin connection and curvature, in addition to torsion, using the superfluid hydrodynamics. the background constitutes an emergent quasirelativistic riemann-cartan spacetime for the weyl quasiparticles which satisfy the conservation laws associated with local lorentz symmetry restricted to the plane of uniaxial anisotropy of the superfluid (or superconductor). moreover, we show that the anomalous galilean momentum conservation is a consequence of the gravitational nieh-yan (ny) chiral anomaly the weyl fermions experience on the background geometry. notably, the ny anomaly coefficient features a nonuniversal ultraviolet cutoff scale λ , with canonical dimensions of momentum. comparison of the anomaly equation and the hydrodynamic equations suggests that the value of the cutoff parameter λ is determined by the normal state fermi liquid and nonrelativistic uniaxial symmetry of the p -wave superfluid or superconductor. | emergent spacetime and gravitational nieh-yan anomaly in chiral p +i p weyl superfluids and superconductors |
we present a simple analytic model that captures the key features of the emission of radiation from material ejected by the merger of neutron stars (nss), and construct the multiband and bolometric luminosity light curves of the transient associated with gw170817, at 2017gfo, using all available data. the ultraviolet to infrared (ir) emission is shown to be consistent with a single ≈0.05 m⊙ component ejecta, with a power-law velocity distribution between {≈ } 0.1c and > 0.3c, a low opacity, κ < 1 cm2 g-1, and a radioactive energy release rate consistent with an initial ye < 0.4. the late-time spectra require an opacity of κν ≈ 0.1 cm2 g-1 at 1 to 2 μm. if this opacity is provided entirely by lanthanides, their implied mass fraction is xln ≈ 10-3, approximately 30 times below the value required to account for the solar abundance. the inferred value of xln is uncertain due to uncertainties in the estimates of ir opacities of heavy elements, which also do not allow the exclusion of a significant contribution to the opacity by other elements (the existence of a slower ejecta rich in lanthanides, which does not contribute significantly to the luminosity, can also not be ruled out). the existence of relatively massive, ≈0.05 m⊙, ejecta with high velocity and low opacity is in tension with the results of numerical simulations of ns mergers. | constraints on the ejecta of the gw170817 neutron star merger from its electromagnetic emission |
the "gravitational memory effect" due to an exact plane wave provides us with an elementary description of the diffeomorphisms associated with the analogue of "soft gravitons for this nonasymptotically flat system. we explain how the presence of the latter may be detected by observing the motion of freely falling particles or other forms of gravitational wave detection. numerical calculations confirm the relevance of the first, second and third time integrals of the riemann tensor pointed out earlier. solutions for various profiles are constructed. it is also shown how to extend our treatment to einstein-maxwell plane waves and a midisuperspace quantization is given. | soft gravitons and the memory effect for plane gravitational waves |
grb 160821b is a short duration gamma-ray burst (grb) detected and localized by the neil gehrels swift observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of 16 kpc from the galaxy's center. we present x-ray, optical/nir, and radio observations of its counterpart and model them with two distinct components of emission: a standard afterglow, arising from the interaction of the relativistic jet with the surrounding medium, and a kilonova, powered by the radioactive decay of the sub-relativistic ejecta. broadband modelling of the afterglow data reveals a weak reverse shock propagating backward into the jet, and a likely jet-break at 3.5 d. this is consistent with a structured jet seen slightly off-axis (θview ∼ θcore) while expanding into a low-density medium (n ≈ 10-3 cm-3). analysis of the kilonova properties suggests a rapid evolution towards red colours, similar to at2017gfo, and a low-nir luminosity, possibly due to the presence of a long-lived neutron star. the global properties of the environment, the inferred low mass (mej ≲ 0.006 m⊙) and velocities (vej ≳ 0.05c) of lanthanide-rich ejecta are consistent with a binary neutron star merger progenitor. | the afterglow and kilonova of the short grb 160821b |
we derive the gravitational waves for f ("t,b") gravity which is an extension of teleparallel gravity and demonstrate that it is equivalent to f(r) gravity by linearized the field equations in the weak field limit approximation. f(t, b) gravity shows three polarizations: the two standard of general relativity, plus and cross, which are purely transverse with two-helicity, massless tensor polarization modes, and an additional massive scalar mode with zero-helicity. the last one is a mix of longitudinal and transverse breathing scalar polarization modes. the boundary term b excites the extra scalar polarization and the mass of scalar field breaks the symmetry of the tt gauge by adding a new degree of freedom, namely a single mixed scalar polarization. | weak field limit and gravitational waves in f(t, b) teleparallel gravity |
in an attempt to advance the understanding of the earth's weather and climate by representing deep convection explicitly, we present a global, four-month simulation (november 2018 to february 2019) with ecmwf's hydrostatic integrated forecasting system (ifs) at an average grid spacing of 1.4 km. the impact of explicitly simulating deep convection on the atmospheric circulation and its variability is assessed by comparing the 1.4 km simulation to the equivalent well-tested and calibrated global simulations at 9 km grid spacing with and without parametrized deep convection. the explicit simulation of deep convection at 1.4 km results in a realistic large-scale circulation, better representation of convective storm activity, and stronger convective gravity wave activity when compared to the 9 km simulation with parametrized deep convection. comparison of the 1.4 km simulation to the 9 km simulation without parametrized deep convection shows that switching off deep convection parametrization at a too coarse resolution (i.e., 9 km) generates too strong convective gravity waves. based on the limited statistics available, improvements to the madden-julian oscillation or tropical precipitation are not observed at 1.4 km, suggesting that other earth system model components and/or their interaction are important for an accurate representation of these processes and may well need adjusting at deep convection resolving resolutions. overall, the good agreement of the 1.4 km simulation with the 9 km simulation with parametrized deep convection is remarkable, despite one of the most fundamental parametrizations being turned off at 1.4 km resolution and despite no adjustments being made to the remaining parametrizations. | a baseline for global weather and climate simulations at 1 km resolution |
high-dimensional probability density estimation for inference suffers from the "curse of dimensionality". for many physical inference problems, the full posterior distribution is unwieldy and seldom used in practice. instead, we propose direct estimation of lower-dimensional marginal distributions, bypassing high-dimensional density estimation or high-dimensional markov chain monte carlo (mcmc) sampling. by evaluating the two-dimensional marginal posteriors we can unveil the full-dimensional parameter covariance structure. we additionally propose constructing a simple hierarchy of fast neural regression models, called moment networks, that compute increasing moments of any desired lower-dimensional marginal posterior density; these reproduce exact results from analytic posteriors and those obtained from masked autoregressive flows. we demonstrate marginal posterior density estimation using high-dimensional ligo-like gravitational wave time series and describe applications for problems of fundamental cosmology. | solving high-dimensional parameter inference: marginal posterior densities & moment networks |
cosmological solitonic objects such as monopoles, cosmic strings, domain walls, oscillons and q-balls often appear in theories of the early universe. we demonstrate that such scenarios are generically accompanied by a novel production source of gravitational waves stemming from soliton isocurvature perturbations. the resulting induced universal gravitational waves (ugws) reside at lower frequencies compared to gravitational waves typically associated with soliton formation. we show that ugws from axion-like particle (alp) oscillons, originating from alp misalignment, extend the frequency range of produced gravitational waves by more than two orders of magnitude regardless of the alp mass and decay constant and can be observable in upcoming gravitational wave experiments. ugws open a new route for gravitational wave signatures in broad classes of cosmological theories. | universal gravitational wave signatures of cosmological solitons |
we perform the first search for an isotropic non-tensorial gravitational-wave background (gwb) allowed in general metric theories of gravity in the north american nanohertz observatory for gravitational waves (nanograv) 12.5-year data set. by modeling the gwb as a power-law spectrum, we find strong bayesian indication for a spatially correlated process with scalar transverse (st) correlations whose bayes factor versus the spatially uncorrelated common-spectrum process is 107 ± 7, but no statistically significant evidence for the tensor transverse, vector longitudinal, and scalar longitudinal polarization modes. the median and the 90% equal-tail amplitudes of st mode are ast=1.06-0.28+0.35×10-15, or equivalently the energy density parameter per logarithm frequency is ωgwst=1.54-0.71+1.21×10-9, at frequency of 1/year. | non-tensorial gravitational wave background in nanograv 12.5-year data set |
unveiling the true nature of dark matter, which manifests itself only through gravity, is one of the principal quests in physics. leading candidates for dark matter are weakly interacting massive particles or ultralight bosons (axions), at opposite extremes in mass scales, that have been postulated by competing theories to solve deficiencies in the standard model of particle physics. whereas dark matter weakly interacting massive particles behave like discrete particles (ϱdm), quantum interference between dark matter axions is manifested as waves (ψdm). here, we show that gravitational lensing leaves signatures in multiply lensed images of background galaxies that reveal whether the foreground lensing galaxy inhabits a ϱdm or ψdm halo. whereas ϱdm lens models leave well documented anomalies between the predicted and observed brightnesses and positions of multiply lensed images, ψdm lens models correctly predict the level of anomalies remaining with ϱdm lens models. more challengingly, when subjected to a battery of tests for reproducing the quadruply lensed triplet images in the system hs 0810+2554, ψdm is able to reproduce all aspects of this system whereas ϱdm often fails. the ability of ψdm to resolve lensing anomalies even in demanding cases such as hs 0810+2554, together with its success in reproducing other astrophysical observations, tilt the balance toward new physics invoking axions. | einstein rings modulated by wavelike dark matter from anomalies in gravitationally lensed images |
we propose a novel way of probing high-scale dirac leptogenesis, a viable alternative to the canonical leptogenesis scenario where the total lepton number is conserved, keeping light standard model neutrinos purely dirac. the simplest possible seesaw mechanism for generating light dirac neutrinos involves heavy singlet dirac fermions and a singlet scalar. in addition to unbroken global lepton number, a discrete z2 symmetry is imposed to forbid direct coupling between right and left chiral parts of light dirac neutrinos. generating light dirac neutrino mass requires the singlet scalar to acquire a vacuum expectation value (vev) that also breaks the z2 symmetry, leading to the formation of domain walls in the early universe. these walls, if made unstable by introducing a soft z2-breaking term, generate gravitational waves (gws) with a spectrum characterized by the wall tension or the singlet vev, and the soft symmetry breaking scale. the scale of leptogenesis depends on the z2-breaking singlet vev, which is also responsible for the tension of the domain wall, affecting the amplitude of gws produced from the collapsing walls. we find that most of the near-future gw observatories will be able to probe dirac leptogenesis scales all the way up to 1011 gev . | probing high scale dirac leptogenesis via gravitational waves from domain walls |
an additional u (1 ) gauge interaction is one of the promising extensions of the standard model of particle physics. among others, the u (1 )b-l gauge symmetry is particularly interesting because it addresses the origin of majorana masses of right-handed neutrinos, which naturally leads to tiny light neutrino masses through the seesaw mechanism. we show that, based on the minimal u (1 )b-l model, the symmetry breaking of the extra u (1 ) gauge symmetry with its minimal higgs sector in the early universe can exhibit the first-order phase transition and hence generate a large enough amplitude of stochastic gravitational wave radiation that is detectable in future experiments. | gravitational waves from the minimal gauged u (1 )b-l model |
the dynamics of a cosmological (de)confinement phase transition is studied in nearly conformally invariant field theories, where confinement is predominantly spontaneously generated and associated with a light "dilaton" field. we show how the leading contribution to the transition rate can be computed within the dilaton effective theory. in the context of composite higgs theories, we demonstrate that a simple scenario involving two renormalization-group fixed points can make the transition proceed much more rapidly than in the minimal scenario, thereby avoiding excessive dilution of matter abundances generated before the transition. the implications for gravitational wave phenomenology are discussed. in general, we find that more (less) rapid phase transitions are associated with weaker (stronger) gravitational wave signals. the various possible features of the strongly coupled composite higgs phase transition discussed here can be concretely modeled at weak coupling within the ads/cft dual randall-sundrum extra-dimensional description, which offers important insights into the nature of the transition and its theoretical control. these aspects will be presented in a companion paper. | cosmological phase transition of spontaneous confinement |
we describe the multi-band template analysis (mbta) search for gravitational waves signals from coalescences of compact objects in the ligo-virgo data, at the time of the third observing run (2019-2020), both for low-latency detections and for offline analysis. details are given on the architecture and functioning of the pipeline, including transient noise mitigation strategies, parameter space for the searched signals, detection of candidates and evaluation of a false alarm rate associated to them. the performance of the low-latency search is demonstrated based on the ligo-virgo third observing run, during which mbta has contributed to 42 alerts, submitting candidates with a median latency of 36 s. the performance of the offline search is illustrated on a subset of data collected during the second ligo-virgo observation run in 2017, and are quantified based on injections of simulated signal events on the same data. | the mbta pipeline for detecting compact binary coalescences in the third ligo-virgo observing run |
placing a large mass in a large spatial superposition, such as a schrödinger cat state, is a significant and important challenge. in particular, the large spatial superposition [o (10 -100 )µ m ] of mesoscopic masses [m ∼o (10−14-10−15) kg ] makes it possible to test the quantum nature of gravity via entanglement in the laboratory. to date, the proposed methods of achieving this spatial delocalization are to use wave-packet expansions or quantum ancilla- (for example, spin-) dependent forces, all of whose efficacy reduces with mass. thus increasing the spatial splitting independently of the mass is an important open challenge. in this paper we present a method of achieving a mass-independent enhancement of superposition via diamagnetic repulsion from current-carrying wires. we analyze an example system which uses the stern-gerlach effect to creating a small initial splitting and then apply our diamagnetic repulsion method to enhance the superposition size o (400 -600 )µ m from an initial modest split of the wave function. we provide an analytical and numerical analysis of our scheme. | mass-independent scheme for enhancing spatial quantum superpositions |
ultracompact binaries with orbital periods less than a few hours will dominate the gravitational wave signal in the mhz regime. until recently, 10 systems were expected to have a predicted gravitational wave signal strong enough to be detectable by the laser interferometer space antenna (lisa), the so-called `verification binaries'. system parameters, including distances, are needed to provide an accurate prediction of the expected gravitational wave strength to be measured by lisa. using parallaxes from gaia data release 2 we calculate signal-to-noise ratios (snr) for ≈50 verification binary candidates. we find that 11 binaries reach an snr ≥ 20, two further binaries reaching an snr≥ 5, and three more systems are expected to have a snr≈ 5 after 4 yr integration with lisa. for these 16 systems, we present predictions of the gravitational wave amplitude (a) and parameter uncertainties from fisher information matrix on the amplitude (a) and inclination (ι). | lisa verification binaries with updated distances from gaia data release 2 |
we introduce a model for matter genesis in which both the baryonic and dark matter asymmetries originate from a first-order phase transition in a dark sector with an s u (3 )×s u (2 )×u (1 ) gauge group and minimal matter content. in the simplest scenario, we predict that dark matter is a dark antineutron with mass of either mn ¯=1.36 gev or mn ¯=1.63 gev . alternatively, dark matter may be comprised of equal numbers of dark antiprotons and pions. in either scenario, this model is highly discoverable through both dark matter direct detection and dark photon search experiments. the strong dark matter self-interactions may ameliorate small-scale structure problems, while the strongly first-order phase transition may be confirmed at future gravitational wave observatories. | asymmetric matter from a dark first-order phase transition |
wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. therefore, experimental tests of collapse models are also fundamental tests of quantum mechanics. here, we compute the upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors ligo, lisa pathfinder, and auriga. we consider the most widely used collapse model, the continuous spontaneous localization (csl) model. we show that these experiments exclude a huge portion of the csl parameter space, the strongest bound being set by the recently launched space mission lisa pathfinder. we also rule out a proposal for quantum-gravity-induced decoherence. | experimental bounds on collapse models from gravitational wave detectors |
a generic feature of string compactifications is the presence of many scalar fields, called moduli. moduli are usually displaced from their post-inflationary minimum during inflation. their relaxation to the minimum could lead to the production of oscillons: localised, long-lived, non-linear excitations of the scalar fields. here we discuss under which conditions oscillons can be produced in string cosmology and illustrate their production and potential phenomenology with two explicit examples: the case of an initially displaced volume modulus in the kklt scenario and the case of a displaced blow-up kähler modulus in the large volume scenario (lvs). one, in principle, observable consequence of oscillon dynamics is the production of gravitational waves which, contrary to those produced from preheating after high scale inflation, could have lower frequencies, closer to the currently observable range. we also show that, for the considered parameter ranges, oscillating fibre and volume moduli do not develop any significant non-perturbative dynamics. furthermore, we find that the vacua in the lvs and the kklt scenario are stable against local overshootings of the field into the decompatification region, which provides an additional check on the longevity of these metastable configurations. | oscillons from string moduli |
context. the astrophysical r-process site where about half of the elements, heavier than iron are produced, has been a puzzle for several decades. here we discuss the role of one of the leading ideas - neutron star mergers (nsms) - in the light of the first direct detection of such an event in both gravitational (gw) and electromagnetic (em) waves.aims: our aim is to understand the implications of the first gw/em observations of a nsm for cosmic nucleosynthesis.methods: we analyse bolometric and nir lightcurves of the first detected double nsm and compare them to nuclear reaction network-based macronova models.results: the slope of the bolometric lightcurve is consistent with the radioactive decay of neutron star ejecta with ye ≲ 0.3 (but not larger), which provides strong evidence for an r-process origin of the electromagnetic emission. this rules out in particular "nickel winds" as major source of the emission. we find that the nir lightcurves can be well fitted either with or without lanthanide-rich ejecta. our limits on the ejecta mass together with estimated rates directly confirm earlier purely theoretical or indirect observational conclusions that double neutron star mergers are indeed a major site of cosmic nucleosynthesis. if the ejecta mass was typical, nsms can easily produce all of the estimated galactic r-process matter, and - depending on the real rate - potentially even more. this could be a hint that the event ejected a particularly large amount of mass, maybe due to a substantial difference between the component masses. this would be compatible with the mass limits obtained from the gw-observation.conclusions: the recent observations suggests that nsms are responsible for a broad range of r-process nuclei and that they are at least a major, but likely the dominant r-process site in the universe. | the first direct double neutron star merger detection: implications for cosmic nucleosynthesis |
we present a search for dark photon dark matter that could couple to gravitational-wave interferometers using data from advanced ligo and virgo's third observing run. to perform this analysis, we use two methods, one based on cross-correlation of the strain channels in the two nearly aligned ligo detectors, and one that looks for excess power in the strain channels of the ligo and virgo detectors. the excess power method optimizes the fourier transform coherence time as a function of frequency, to account for the expected signal width due to doppler modulations. we do not find any evidence of dark photon dark matter with a mass between ma∼10-14- 10-11 ev /c2 , which corresponds to frequencies between 10-2000 hz, and therefore provide upper limits on the square of the minimum coupling of dark photons to baryons, i.e., u (1 )b dark matter. for the cross-correlation method, the best median constraint on the squared coupling is ∼1.31 ×10-47 at ma∼4.2 ×10-13 ev /c2 ; for the other analysis, the best constraint is ∼2.4 ×10-47 at ma∼5.7 ×10-13 ev /c2. these limits improve upon those obtained in direct dark matter detection experiments by a factor of ∼100 for ma∼[2 - 4 ]×10-13 ev /c2 , and are, in absolute terms, the most stringent constraint so far in a large mass range ma∼2 ×10-13- 8 ×10-12 ev /c2 . | constraints on dark photon dark matter using data from ligo's and virgo's third observing run |
we estimate the rate and the luminosity function of short (hard) gamma-ray bursts (sgrbs) that are non-collapsars, using the peak fluxes and redshifts of batse, swift and fermi grbs. following bromberg et al., we select a sub-sample of swift bursts which are most likely non-collapsars. we find that these sgrbs are delayed relative to the global star formation rate (sfr) with a typical delay time of a 3-4 gyr (depending on the sfr model). however, if two or three sgrb at high redshifts have been missed because of selection effects, a distribution of delay times of ∝ 1/t would be also compatible. the current event rate of these non-collapsar sgrbs with liso > 5 × 1049 erg s-1 is 4.1_{-1.9}^{+2.3} gpc^{-3} yr^{-1}. the rate was significantly larger around z ∼ 1 and it declines since that time. the luminosity function we find is a broken power law with a break at 2.0_{-0.4}^{+1.4} × 10^{52} erg s^{-1} and power-law indices 0.95_{-0.1 2}^{+0.12} and 2.0_{-0.8}^{+1.0}. when considering the whole swift sgrb sample we find that it is composed of two populations: one group (≈60-80 per cent of swift sgrbs) with the above rate and time delay and a second group (≈20-40 per cent of swift sgrbs) of potential `impostors' that follow the sfr with no delay. these two populations are in very good agreement with the division of sgrbs to non-collapsars and collapsars suggested recently by bromberg et al. if non-collapsar sgrbs arise from neutron star merger this rate suggest a detection rate of 3-100 yr-1 by a future gravitational wave detectors (e.g. advanced ligo/virgo with detection horizon on 300 mpc), and a co-detection with fermi (swift ) rate of 0.1-1 yr-1 (0.02-0.14 yr-1). we estimate that about 4 × 10^5 (f_b^{-1}/30) mergers took place in the milky way. if 0.025m⊙ were ejected in each event this would have been sufficient to produce all the heavy r-process material in the galaxy. | the rate, luminosity function and time delay of non-collapsar short grbs |
in this letter, we show that the dimensionless parameters in the generalized uncertainty principle (gup) can be constrained by the gravitational wave event gw150914, which was discovered by the ligo scientific and virgo collaborations. firstly, according to the heisenberg uncertainty principle (hup) and the data of gravitational wave event gw150914, we derive the standard energy-momentum dispersion relation and calculate the difference between the propagation speed of gravitons and the speed of light, i.e., δυ. next, using two proposals regarding the gup, we also generalize our study to the quantum gravity case and obtain the modified speed of gravitons. finally, based on the modified speed of gravitons and δυ, the improved upper bounds on the gup parameters are obtained. the results show that the upper limits of the gup parameters β0 and α0 are 2.3 ×1060 and 1.8 ×1020. | constraining the generalized uncertainty principle with the gravitational wave event gw150914 |
the consequences of phase transitions in the early universe are becoming testable in a variety of manners, from colliders physics to gravitational wave astronomy. in particular one phase transition we know of, the electroweak phase transition (ewpt), could potentially be first order in bsm scenarios and testable in the near future. if confirmed this could provide a mechanism for baryogenesis, which is one of the most important outstanding questions in physics. to reliably make predictions it is necessary to have full control of the finite temperature scalar potentials. however, as we show the standard methods used in bsm physics to improve phase transition calculations, resumming hard thermal loops, introduces significant errors into the scalar potential. in addition, the standard methods make it impossible to match theories to an eft description reliably. in this paper we define a thermal resummation procedure based on partial dressing (pd) for general bsm calculations of phase transitions beyond the high-temperature approximation. additionally, we introduce the modified optimized partial dressing (opd) procedure, which is numerically nearly as efficient as old incorrect methods, while yielding identical results to the full pd calculation. this can be easily applied to future bsm studies of phase transitions in the early universe. as an example, we show that in unmixed singlet scalar extensions of the sm, the (o)pd calculations make new phenomenological predictions compared to previous analyses. an important future application is the study of efts at finite temperature. | thermal resummation and phase transitions |
we explore the prospects of detecting galactic double white dwarf (dwd) binaries with the space-based gravitational wave (gw) observatory tianqin. in this work, we analyze both a sample of currently known dwds and a realistic synthetic population of dwds to assess the number of guaranteed detections and the full capacity of the mission. we find that tianqin can detect 12 out of ∼100 known dwds; gw signals of these binaries can be modeled in detail ahead of the mission launch, and therefore they can be used as verification sources. besides, we estimate that tianqin has a potential to detect as many as 104 dwds in the milky way. tianqin is expected to measure their orbital periods and amplitudes with accuracies of ∼10-7 and ∼0.2 , respectively, and to localize on the sky a large fraction (39%) of the detected population to better than 1 deg2 . we conclude that tianqin has the potential to significantly advance our knowledge on galactic dwds by increasing the sample up to 2 orders of magnitude, and will allow their multimessenger studies in combination with electromagnetic telescopes. we also test the possibilities of different configurations of tianqin: (1) the same mission with a different orientation, (2) two perpendicular constellations combined into a network, and (3) the combination of the network with the esa-led laser interferometer space antenna. we find that the network of detectors boosts the accuracy on the measurement of source parameters by 1-2 orders of magnitude, with the improvement on sky localization being the most significant. | science with the tianqin observatory: preliminary results on galactic double white dwarf binaries |
in the absence of numerous gravitational-wave detections with confirmed electromagnetic counterparts, the "dark siren" method has emerged as a leading technique of gravitational-wave cosmology. the method allows redshift information of such events to be inferred statistically from a catalogue of potential host galaxies. due to selection effects, dark siren analyses necessarily depend on the mass distribution of compact objects and the evolution of their merger rate with redshift. informative priors on these quantities will impact the inferred posterior constraints on the hubble constant (h 0). it is thus crucial to vary these unknown distributions during an h 0 inference. this was not possible in earlier analyses due to the high computational cost, restricting them to either excluding galaxy catalogue information, or fixing the gravitational-wave population mass distribution and risking introducing bias to the h 0 measurement. this paper introduces a significantly enhanced version of the python package gwcosmo, which allows joint estimation of cosmological and compact binary population parameters. this thereby ensures the analysis is now robust to a major source of potential bias. the gravitational-wave events from the third gravitational-wave transient catalogue are reanalysed with the glade+ galaxy catalogue, and an updated, more reliable measurement of h 0 = 69+12 -7 km s-1 mpc-1 is found (maximum a posteriori probability and 68% highest density interval). this improved method will enable cosmological analyses with future gravitational-wave detections to make full use of the information available (both from galaxy catalogues and the compact binary population itself), leading to promising new independent bounds on the hubble constant. | joint cosmological and gravitational-wave population inference using dark sirens and galaxy catalogues |
compared to light interferometers, the flux in cold-atom interferometers is low and the associated shot noise is large. sensitivities beyond these limitations require the preparation of entangled atoms in different momentum modes. here, we demonstrate a source of entangled atoms that is compatible with state-of-the-art interferometers. entanglement is transferred from the spin degree of freedom of a bose-einstein condensate to well-separated momentum modes, witnessed by a squeezing parameter of -3.1 (8 ) db . entanglement-enhanced atom interferometers promise unprecedented sensitivities for quantum gradiometers or gravitational wave detectors. | momentum entanglement for atom interferometry |
gravitational wave (gw) sources are an excellent probe of the luminosity distance and offer a novel measure of the hubble constant, h0. this estimation of h0 from standard sirens requires an accurate estimation of the cosmological redshift of the host galaxy of the gw source after correcting for its peculiar velocity. the absence of an accurate peculiar velocity correction affects both the precision and accuracy of the measurement of h0, particularly for nearby sources. here, we propose a framework to incorporate such a peculiar velocity correction for gw sources. a first implementation of our method to the event gw170817, combined with observations taken with very large baseline interferometry (vlbi), leads to a revised value of h0 = 68.3-4.5+4.6 km s-1 mpc-1. while this revision is minor, it demonstrates that our method makes it possible to obtain unbiased and accurate measurements of h0 at the precision required for the standard siren cosmology. | velocity correction for hubble constant measurements from standard sirens |
we show that the new precise measurements of cosmic microwave background (cmb) temperature and polarization anisotropies made by the planck satellite significantly improves previous constraints on the cosmic gravitational waves background (cgwb) at frequencies f >10-15 hz. on scales smaller than the horizon at the time of decoupling, primordial gravitational waves contribute to the total radiation content of the universe. considering adiabatic perturbations, cgwb affects temperature and polarization cmb power spectra and matter power spectrum in a manner identical to relativistic particles. considering the latest planck results we constrain the cgwb energy density to ωgwh2 < 1.7 ×10-6 at 95% cl. combining cmb power spectra with lensing, bao and primordial deuterium abundance observations, we obtain ωgwh2 < 1.2 ×10-6 at 95% cl, improving previous planck bounds by a factor 3 and the recent direct upper limit from the ligo and virgo experiments a factor 2. a combined analysis of future satellite missions as core and euclid could improve current bound by more than an order of magnitude. | new constraints on primordial gravitational waves from planck 2015 |
the glueball dark matter, in the pure su (n ) yang-mills theory, engenders dark su (n ) stars that comprise self-gravitating compact configurations of scalar glueball fields. corrections to the highest frequency of gravitational wave radiation emitted by dark su (n ) star mergers on a fluid brane with variable tension, implemented by the minimal geometric deformation, are derived, and their consequences are analyzed. hence, dark su (n ) star mergers on a fluid braneworld are shown to be better detectable by the ligo and the elisa experiments. | dark su (n ) glueball stars on fluid branes |
the cross-correlation of gravitational wave strain with upcoming galaxy surveys probes theories of gravity in a new way. this method enables testing the theory of gravity by combining the effects from both gravitational lensing of gravitational waves and the propagation of gravitational waves in space-time. we find that within 10 yr the combination of the advanced ligo (laser interferometer gravitational-wave observatory) and virgo (virgo interferometer) detector networks with planned galaxy surveys should detect weak gravitational lensing of gravitational waves in the low-redshift universe (z < 0.5). with the next-generation gravitational wave experiments such as voyager, lisa (laser interferometer space antenna), cosmic explorer, and the einstein telescope, we can extend this test of the theory of gravity to larger redshifts by exploiting the synergies between electromagnetic wave and gravitational wave probes. | probing the theory of gravity with gravitational lensing of gravitational waves and galaxy surveys |
we realize beam splitters and mirrors for atom waves by employing a sequence of light pulses rather than individual ones. in this way we can tailor atom interferometers with improved sensitivity and accuracy. we demonstrate our method of composite pulses by creating a symmetric matter-wave interferometer which combines the advantages of conventional bragg- and raman-type concepts. this feature leads to an interferometer with a high immunity to technical noise allowing us to devise a large-area sagnac gyroscope yielding a phase shift of 6.5 rad due to the earth's rotation. with this device we achieve a rotation rate precision of 120 nrad s-1 hz-1 /2 and determine the earth's rotation rate with a relative uncertainty of 1.2%. | composite-light-pulse technique for high-precision atom interferometry |
in continuously monitored systems the standard quantum limit is given by the trade-off between shot noise and back-action noise. in gravitational-wave detectors, such as advanced ligo, both contributions can be simultaneously squeezed in a broad frequency band by injecting a spectrum of squeezed vacuum states with a frequency-dependent squeeze angle. this approach requires setting up an additional long baseline, low-loss filter cavity in a vacuum system at the detector's site. here, we show that the need for such a filter cavity can be eliminated, by exploiting einstein-podolsky-rosen (epr)-entangled signals and idler beams. by harnessing their mutual quantum correlations and the difference in the way each beam propagates in the interferometer, we can engineer the input signal beam to have the appropriate frequency-dependent conditional squeezing once the out-going idler beam is detected. our proposal is appropriate for all future gravitational-wave detectors for achieving sensitivities beyond the standard quantum limit. | proposal for gravitational-wave detection beyond the standard quantum limit through epr entanglement |
in the weak field regime, gravitational waves can be considered as being made up of collisionless, relativistic tensor modes that travel along null geodesics of the perturbed background metric. we work in this geometric optics picture to calculate the anisotropies in gravitational wave backgrounds resulting from astrophysical and cosmological sources. our formalism yields expressions for the angular power spectrum of the anisotropies. we show how the anisotropies are sourced by intrinsic, doppler, sachs-wolfe, and integrated sachs-wolfe terms in analogy with cosmic microwave background photons. | anisotropies of gravitational wave backgrounds: a line of sight approach |
photonics enables to develop simple lab experiments that mimic water rogue wave generation phenomena, as well as relativistic gravitational effects such as event horizons, gravitational lensing and hawking radiation. the basis for analog gravity experiments is light propagation through an effective moving medium obtained via the nonlinear response of the material. so far, analogue gravity kinematics was reproduced in scalar optical wave propagation test models. multimode and spatiotemporal nonlinear interactions exhibit a rich spectrum of excitations, which may substantially expand the range of rogue wave phenomena, and lead to novel space-time analogies, for example with multi-particle interactions. by injecting two colliding and modulated pumps with orthogonal states of polarization in a randomly birefringent telecommunication optical fiber, we provide the first experimental demonstration of an optical dark rogue wave. we also introduce the concept of multi-component analog gravity, whereby localized spatiotemporal horizons are associated with the dark rogue wave solution of the two-component nonlinear schrödinger system. | optical dark rogue wave |
we assess the value of machine learning as an accelerator for the parameterization schemes of operational weather forecasting systems, specifically the parameterization of nonorographic gravity wave drag. emulators of this scheme can be trained to produce stable and accurate results up to seasonal forecasting timescales. generally, networks that are more complex produce emulators that are more accurate. by training on an increased complexity version of the existing parameterization scheme, we build emulators that produce more accurate forecasts. for medium range forecasting, we have found evidence that our emulators are more accurate than the version of the parametrization scheme that is used for operational predictions. using the current operational cpu hardware, our emulators have a similar computational cost to the existing scheme, but are heavily limited by data movement. on gpu hardware, our emulators perform 10 times faster than the existing scheme on a cpu. | machine learning emulation of gravity wave drag in numerical weather forecasting |
building on global adjoint tomography model glad-m15, we present transversely isotropic global model glad-m25, which is the result of 10 quasi-newton tomographic iterations with an earthquake database consisting of 1480 events in the magnitude range 5.5 ≤ mw ≤ 7.2, an almost sixfold increase over the first-generation model. we calculated fully 3-d synthetic seismograms with a shortest period of 17 s based on a gpu-accelerated spectral-element wave propagation solver which accommodates effects due to 3-d anelastic crust and mantle structure, topography and bathymetry, the ocean load, ellipticity, rotation and self-gravitation. we used an adjoint-state method to calculate fréchet derivatives in 3-d anelastic earth models facilitated by a parsimonious storage algorithm. the simulations were performed on the cray xk7 'titan' and the ibm power 9 'summit' at the oak ridge leadership computing facility. we quantitatively evaluated glad-m25 by assessing misfit reductions and traveltime anomaly histograms in 12 measurement categories. we performed similar assessments for a held-out data set consisting of 360 earthquakes, with results comparable to the actual inversion. we highlight the new model for a variety of plumes and subduction zones. | global adjoint tomography—model glad-m25 |
the advanced virgo detector has contributed with its data to the rapid growth of the number of detected gw signals in the past few years, alongside the two advanced ligo instruments. first during the last month of the observation run 2 (o2) in august 2017 (with, most notably, the compact binary mergers gw170814 and gw170817), and then during the full observation run 3 (o3): an 11 months data taking period, between april 2019 and march 2020, that led to the addition of 79 events to the catalog of transient gw sources maintained by ligo, virgo and now kagra. these discoveries and the manifold exploitation of the detected waveforms benefit from an accurate characterization of the quality of the data, such as continuous study and monitoring of the detector noise sources. these activities, collectively named detector characterization and data quality or detchar, span the whole workflow of the virgo data, from the instrument front-end hardware to the final analyses. they are described in detail in the following article, with a focus on the results achieved by the virgo detchar group during the o3 run. concurrently, a companion article describes the tools that have been used by the virgo detchar group to perform this work. | virgo detector characterization and data quality: results from the o3 run |
we review the prospects for detecting quark matter in neutron star cores. we survey the proposed signatures and emphasize the importance of data from neutron star mergers, which provide access to dynamical properties that operate on short timescales that are not probed by most other neutron star observables. | signatures for quark matter from multi-messenger observations |
we revisit double neutron star (dns) formation in the classical binary evolution scenario in light of the recent laser interferometer gravitational-wave observatory (ligo)/virgo dns detection (gw170817). the observationally estimated galactic dns merger rate of r_mw = 21^{+28}_{-14} myr-1, based on three galactic dns systems, fully supports our standard input physics model with rmw = 24 myr-1. this estimate for the galaxy translates in a non-trivial way (due to cosmological evolution of progenitor stars in chemically evolving universe) into a local (z ≈ 0) dns merger rate density of rlocal = 48 gpc-3 yr-1, which is not consistent with the current ligo/virgo dns merger rate estimate (1540^{+3200}_{-1220} gpc-3 yr-1). within our study of the parameter space, we find solutions that allow for dns merger rates as high as r_local ≈ 600^{+600}_{-300} gpc-3 yr-1 which are thus consistent with the ligo/virgo estimate. however, our corresponding bh-bh merger rates for the models with high dns merger rates exceed the current ligo/virgo estimate of local bh-bh merger rate (12-213 gpc-3 yr-1). apart from being particularly sensitive to the common envelope treatment, dns merger rates are rather robust against variations of several of the key factors probed in our study (e.g. mass transfer, angular momentum loss, and natal kicks). this might suggest that either common envelope development/survival works differently for dns (∼10-20 m⊙ stars) than for bh-bh (∼40-100 m⊙ stars) progenitors, or high black hole (bh) natal kicks are needed to meet observational constraints for both types of binaries. our conclusion is based on a limited number of (21) evolutionary models and is valid within this particular dns and bh-bh isolated binary formation scenario. | double neutron stars: merger rates revisited |
the probability of primordial black hole (pbh) formation is known to be boosted during the quantum chromodynamics (qcd) crossover due to a slight reduction of the equation of state. this induces a high peak and other features in the pbh mass distribution. but the impact of this variation during the process of pbh formation has so far not been considered in numerical simulations. in this work we simulate the formation of pbhs by taking into account the varying equation of state at the qcd epoch, compute the over-density threshold using different curvature profiles and find that the resulting pbh mass distributions are significantly impacted. the expected merger rate distributions of early and late pbh binaries is comparable to the ones inferred from the gwtc-3 catalog for dark matter fractions in pbhs within 0.1 < f pbh < 1. the distribution of gravitational-wave events estimated from the volume sensitivity could explain mergers around 30-50 m ⊙, with asymmetric masses like gw190814, or in the pair-instability mass gap like gw190521. however, none of the considered cases leads to a multi-modal distribution with a secondary peak around 8-15 m ⊙, as suggested by the gwtc-3 catalog, possibly pointing to a mixed population of astrophysical and primordial black holes. | simulations of pbh formation at the qcd epoch and comparison with the gwtc-3 catalog |
we present the merger rate density of population iii binary black holes (bhs) by means of a widely used binary population synthesis code bse with extensions to very massive and extreme metal-poor stars. we consider not only low-mass bhs (lbhs: 5-50m⊙) but also high-mass bhs (hbhs: 130-200m⊙), where lbhs and hbhs are below and above the pair-instability mass gap (50-130m⊙), respectively. population iii bh-bhs can be categorized into three subpopulations: bh-bhs without hbhs (hbh0s: mtot ≲ 100m⊙), with one hbh (hbh1s: mtot ∼ 130-260m⊙), and with two hbhs (hbh2s: mtot ∼ 270-400m⊙), where mtot is the total mass of a bh-bh. their merger rate densities at the current universe are ∼0.1 yr-1 gpc-3 for hbh0s, and ∼0.01 yr-1 gpc-3 for the sum of hbh1s and hbh2s, provided that the mass density of population iii stars is ∼1013m⊙ gpc-3. these rates are modestly insensitive to initial conditions and single star models. the hbh1 and hbh2 mergers can dominate bh-bhs with hbhs discovered in the near future. they have low effective spins ≲0.2 in the current universe. the number ratio of hbh2s to hbh1s is high, ≳0.1. we also find that bhs in the mass gap (up to ∼85m⊙) merge. these merger rates can be reduced to nearly zero if population iii binaries are always wide (≳100r⊙), and if population iii stars always enter into chemically homogeneous evolution. the presence of close population iii binaries (∼10r⊙) is crucial for avoiding the worst scenario. | merger rate density of population iii binary black holes below, above, and in the pair-instability mass gap |
the first detection of gravitational waves by the laser interferometer gravitational-wave observatory (ligo) in 2015 launched the era of gravitational-wave astronomy. the quest for gravitational-wave signals from objects that are fainter or farther away impels technological advances to realize ever more sensitive detectors. since 2019, one advanced technique, the injection of squeezed states of light, is being used to improve the shot-noise limit to the sensitivity of the advanced ligo detectors, at frequencies above ∼50 hz . below this frequency, quantum backaction, in the form of radiation pressure induced motion of the mirrors, degrades the sensitivity. to simultaneously reduce shot noise at high frequencies and quantum radiation pressure noise at low frequencies requires a quantum noise filter cavity with low optical losses to rotate the squeezed quadrature as a function of frequency. we report on the observation of frequency-dependent squeezed quadrature rotation with rotation frequency of 30 hz, using a 16-m-long filter cavity. a novel control scheme is developed for this frequency-dependent squeezed vacuum source, and the results presented here demonstrate that a low-loss filter cavity can achieve the squeezed quadrature rotation necessary for the next planned upgrade to advanced ligo, known as "a + ." | frequency-dependent squeezing for advanced ligo |
internal gravity waves play a primary role in geophysical fluids: they contribute significantly to mixing in the ocean, and they redistribute energy and momentum in the middle atmosphere. until recently, most studies were focused on plane wave solutions. however, these solutions are not a satisfactory description of most geophysical manifestations of internal gravity waves, and it is now recognized that internal wave beams with a confined profile are ubiquitous in the geophysical context. we discuss the reason for the ubiquity of wave beams in stratified fluids, which is related to the fact that they are solutions of the nonlinear governing equations. we focus more specifically on situations with a constant buoyancy frequency. moreover, in light of recent experimental and analytical studies of internal gravity beams, it is timely to discuss the two main mechanisms of instability for those beams: (a) the triadic resonant instability generating two secondary wave beams and (b) the streaming instability corresponding to the spontaneous generation of a mean flow. | instabilities of internal gravity wave beams |
the nature of dark matter remains unknown to date, although several candidate particles are being considered in a dynamically changing research landscape1. scalar field dark matter is a prominent option that is being explored with precision instruments, such as atomic clocks and optical cavities2-8. here we describe a direct search for scalar field dark matter using a gravitational-wave detector, which operates beyond the quantum shot-noise limit. we set new upper limits on the coupling constants of scalar field dark matter as a function of its mass, by excluding the presence of signals that would be produced through the direct coupling of this dark matter to the beam splitter of the geo600 interferometer. these constraints improve on bounds from previous direct searches by more than six orders of magnitude and are, in some cases, more stringent than limits obtained in tests of the equivalence principle by up to four orders of magnitude. our work demonstrates that scalar field dark matter can be investigated or constrained with direct searches using gravitational-wave detectors and highlights the potential of quantum-enhanced interferometry for dark matter detection. | direct limits for scalar field dark matter from a gravitational-wave detector |
the 100 years since the publication of albert einstein's theory of general relativity saw significant development of the understanding of the theory, the identification of potential astrophysical sources of sufficiently strong gravitational waves and development of key technologies for gravitational-wave detectors. in 2015, the first gravitational-wave signals were detected by the two us advanced ligo instruments. in 2017, advanced ligo and the european advanced virgo detectors pinpointed a binary neutron star coalescence that was also seen across the electromagnetic spectrum. the field of gravitational-wave astronomy is just starting, and this roadmap of future developments surveys the potential for growth in bandwidth and sensitivity of future gravitational-wave detectors, and discusses the science results anticipated to come from upcoming instruments. | gravitational-wave physics and astronomy in the 2020s and 2030s |
we investigate cosmic string networks in the abelian higgs model using data from a campaign of large-scale numerical simulations on lattices of up to 409 63 grid points. we observe scaling or self-similarity of the networks over a wide range of scales and estimate the asymptotic values of the mean string separation in horizon length units ξ ˙ and of the mean square string velocity v¯2 in the continuum and large time limits. the scaling occurs because the strings lose energy into classical radiation of the scalar and gauge fields of the abelian higgs model. we quantify the energy loss with a dimensionless radiative efficiency parameter and show that it does not vary significantly with lattice spacing or string separation. this implies that the radiative energy loss underlying the scaling behavior is not a lattice artifact, and justifies the extrapolation of measured network properties to large times for computations of cosmological perturbations. we also show that the core growth method, which increases the defect core width with time to extend the dynamic range of simulations, does not introduce significant systematic error. we compare ξ ˙ and v¯2 to values measured in simulations using the nambu-goto approximation, finding that the latter underestimate the mean string separation by about 25%, and overestimate v¯2 by about 10%. the scaling of the string separation implies that string loops decay by the emission of massive radiation within a hubble time in field theory simulations, in contrast to the nambu-goto scenario which neglects this energy loss mechanism. string loops surviving for only one hubble time emit much less gravitational radiation than in the nambu-goto scenario and are consequently subject to much weaker gravitational wave constraints on their tension. | scaling from gauge and scalar radiation in abelian-higgs string networks |
we provide a refined and much more simplified einstein-gauss-bonnet inflationary theoretical framework, which is compatible with the gw170817 observational constraints on the gravitational wave speed. as in previous works, the constraint that the gravitational wave speed is ${c}_{\text{t}}^{2}=1$ in natural units, results to a constraint differential equation that relates the coupling function of the scalar field to the gauss-bonnet invariant ξ(ϕ) and the scalar potential v(ϕ). adopting the slow-roll conditions for the scalar field and the hubble rate, and in contrast to previous works, by further assuming that $\kappa \frac{{\xi }^{\prime }}{{\xi }^{{\prime\prime}}}\ll 1$, which is motivated by slow-roll arguments, we succeed in providing much more simpler expressions for the slow-roll indices and for the tensor and scalar spectral indices and for the tensor-to-scalar ratio. we exemplify our refined theoretical framework by using an illustrative example with a simple power-law scalar coupling function ξ(ϕ) ~ ϕν and as we demonstrate the resulting inflationary phenomenology is compatible with the latest planck data. moreover, this particular model produces a blue-tilted tensor spectral index, so we discuss in brief the perspective of describing the nanograv result with this model as is indicated in the recent literature. | a refined einstein-gauss-bonnet inflationary theoretical framework |
in this paper, we find the solution of the fractional-order kaup–kupershmidt (kk) equation by implementing the natural decomposition method with the aid of two different fractional derivatives, namely the atangana–baleanu derivative in caputo manner (abc) and caputo–fabrizio (cf). when investigating capillary gravity waves and nonlinear dispersive waves, the kk equation is extremely important. to demonstrate the accuracy and efficiency of the proposed technique, we study the nonlinear fractional kk equation in three distinct cases. the results are given in the form of a series, which converges quickly. the numerical simulations are presented through tables to illustrate the validity of the suggested technique. numerical simulations in terms of absolute error are performed to ensure that the proposed methodologies are trustworthy and accurate. the resulting solutions are graphically shown to ensure the applicability and validity of the algorithms under consideration. the results that we obtain confirm that the proposed method is the best tool for handling any nonlinear problems arising in science and technology. | a comparative analysis of fractional-order kaup–kupershmidt equation within different operators |
the extended minimal geometric deformation (emgd) procedure, in the holographic membrane paradigm, is employed to model stellar distributions that arise upon self-interacting scalar glueball dark matter condensation. such scalar glueballs are su( n) yang-mills hidden sectors beyond the standard model. then, corrections to the gravitational wave radiation, emitted by su( n) emgd dark glueball stars mergers, are derived, and their respective spectra are studied in the emgd framework, due to a phenomenological brane tension with finite value. the bulk weyl fluid that drives the emgd is then proposed to be experimentally detected by enhanced windows at the elisa and ligo. | the extended minimal geometric deformation of su( n) dark glueball condensates |
next generation ground-based gravitational-wave detectors will observe binary black hole (bbh) mergers up to redshift $z\gtrsim 10$ , probing the evolution of compact binary (cb) mergers across cosmic time. here, we present a new data-driven model to estimate the cosmic merger rate density (mrd) evolution of cbs, by coupling catalogs of cb mergers with observational constraints on the cosmic star formation rate (sfr) density and on the metallicity evolution of the universe. we adopt catalogs of cb mergers derived from recent n-body and population-synthesis simulations, to describe the mrd of cbs formed in young star clusters (hereafter, dynamical cbs) and in the field (hereafter, isolated cbs). the local mrd of dynamical bbhs is ${{ \mathcal r }}_{\mathrm{bbh}}={64}_{-20}^{+34}$ gpc-3 yr-1, consistent with the 90% credible interval from the first and second observing runs (o1 and o2) of the ligo-virgo collaboration, and with the local mrd of isolated bbhs ( ${{ \mathcal r }}_{\mathrm{bbh}}={50}_{-37}^{+71}$ gpc-3 yr-1). the local mrd of dynamical and isolated black hole-neutron star binaries is ${{ \mathcal r }}_{\mathrm{bhns}}={41}_{-23}^{+33}$ and ${49}_{-34}^{+48}$ gpc-3 yr-1, respectively. both values are consistent with the upper limit inferred from o1 and o2. finally, the local mrd of dynamical binary neutron stars (bnss, ${{ \mathcal r }}_{\mathrm{bns}}={151}_{-38}^{+59}$ gpc-3 yr-1) is a factor of two lower than the local mrd of isolated bnss ( ${{ \mathcal r }}_{\mathrm{bns}}={283}_{-75}^{+97}$ gpc-3 yr-1). the mrd for all cb classes grows with redshift, reaching its maximum at $z\in [1.5,2.5]$ , and then decreases. this trend springs from the interplay between cosmic sfr, metallicity evolution, and delay time of binary compact objects. | the cosmic merger rate density evolution of compact binaries formed in young star clusters and in isolated binaries |
observations of gravitational-wave signals from binary neutron-star mergers, like gw170817, can be used to constrain the neutron-star equation of state (eos). one method involves modeling the eos and measuring the model parameters through bayesian inference. a previous study [b. d. lackey and l. wade, phys. rev. d 91, 043002 (2015), 10.1103/physrevd.91.043002] has demonstrated the effectiveness of using a phenomenologically parameterized piecewise polytrope to extract constraining information from a simulated population of binary neutron-star mergers. despite its advantages compared to more traditional methods of measuring the tidal deformability of neutron stars, notable deficiencies arise when using this eos model. in this work, we describe in detail the implementation of a model built from a spectral decomposition of the adiabatic index that was used by the ligo-virgo collaboration [arxiv:1805.11581] to constrain the neutron-star eos from gw170817. we demonstrate its overall consistency in recovering the neutron-star eos from a simulated signal to the piecewise-polytropic implementation used by lackey and wade and explain any differences that arise. we find that both models recover consistent tidal information from the simulate signals with tightest constraints on the eos around twice nuclear saturation density. as expected, the statistical error that arises in the piecewise-polytropic representation near the fixed joining densities is greatly reduced by using the spectral model. in addition, we find that our choice of prior can have a dominant effect on eos constraints. | comparing two models for measuring the neutron star equation of state from gravitational-wave signals |
if the peccei-quinn symmetry associated to an axion has ever been restored after inflation, axion strings inevitably produce a contribution to the stochastic gravitational wave background. combining effective field theory analysis with numerical simulations, we show that the resulting gravitational wave spectrum has logarithmic deviations from a scale invariant form with an amplitude that is significantly enhanced at low frequencies. as a result, a single ultralight axion-like particle with a decay constant larger than 1014 gev and any mass between 10-18 ev and 10-28 ev leads to an observable gravitational wave spectrum and is compatible with constraints on the post-inflationary scenario from dark matter overproduction, isocurvature and dark radiation. since the spectrum extends over a wide range of frequencies, the resulting signal could be detected by multiple experiments. we describe straightforward ways in which the peccei-quinn symmetry can be restored after inflation for such decay constants. we also comment on the recent possible nanograv signal in light of our results. | observing invisible axions with gravitational waves |
accretion disks around supermassive black holes (smbhs) are promising sites for stellar mass black hole (bh) mergers due to mass segregation and merger acceleration by disk gas torques. here we show that a gravitational-wave (gw) kick at bh merger causes ram-pressure stripping of gas within the bh hill sphere. if r h ≥ h, the disk height, an off-center uv flare at a bh ∼ 103 rg , emerges within t uv ∼ o(2 days)(a bh/103 rg )(m smbh/108 m ⊙)(v kick/102 km s-1) postmerger and lasts o(r h/v kick) ∼ o(5t uv). the flare emerges with luminosity o(1042erg s-1)(t uv/2days)-1(m hill/1m ⊙)(v kick/102 km s-1)2. active galactic nucleus optical/uv photometry is altered and asymmetric broad emission line profiles can develop after weeks. if r h < h, detectability depends on disk optical depth. follow-up by large optical sky surveys is optimized for small gw error volumes and for laser interferometer gravitational-wave observatory/virgo triggers >50m ⊙. | ram-pressure stripping of a kicked hill sphere: prompt electromagnetic emission from the merger of stellar mass black holes in an agn accretion disk |
the growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. such events have higher masses than are expected in isolated binaries, component spin tilt angles that are misaligned, and/or nonnegligible orbital eccentricities. we investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalog of the ligo-virgo-kagra collaboration with an aligned-spin, moderate-eccentricity waveform model. within this framework, we find that at least four of these events show significant support for eccentricity e 10 ≥ 0.1 at a gravitational-wave frequency of 10 hz (>60% credibility, under a log-uniform eccentricity prior that spans the range 10-4 < e 10 < 0.2). two of these events are new additions to the population: gw191109 and gw200208_22. if the four eccentric candidates are truly eccentric, our results suggest that densely populated star clusters may produce 100% of the observed mergers. however, it remains likely that other formation environments with higher yields of eccentric mergers-for example, active galactic nuclei-also contribute. we estimate that we will be able to confidently distinguish which formation channel dominates the eccentric merger rate after ≳80 detections of events with e 10 ≥ 0.05 at ligo-virgo sensitivity, with only ~5 detectably eccentric events required to distinguish formation channels with third-generation gravitational-wave detectors. | four eccentric mergers increase the evidence that ligo-virgo-kagra's binary black holes form dynamically |
with the first direct detection of gravitational waves, the advanced laser interferometer gravitational-wave observatory (ligo) has initiated a new field of astronomy by providing an alternative means of sensing the universe. the extreme sensitivity required to make such detections is achieved through exquisite isolation of all sensitive components of ligo from non-gravitational-wave disturbances. nonetheless, ligo is still susceptible to a variety of instrumental and environmental sources of noise that contaminate the data. of particular concern are noise features known as glitches, which are transient and non-gaussian in their nature, and occur at a high enough rate so that accidental coincidence between the two ligo detectors is non-negligible. glitches come in a wide range of time-frequency-amplitude morphologies, with new morphologies appearing as the detector evolves. since they can obscure or mimic true gravitational-wave signals, a robust characterization of glitches is paramount in the effort to achieve the gravitational-wave detection rates that are predicted by the design sensitivity of ligo. this proves a daunting task for members of the ligo scientific collaboration alone due to the sheer amount of data. in this paper we describe an innovative project that combines crowdsourcing with machine learning to aid in the challenging task of categorizing all of the glitches recorded by the ligo detectors. through the zooniverse platform, we engage and recruit volunteers from the public to categorize images of time-frequency representations of glitches into pre-identified morphological classes and to discover new classes that appear as the detectors evolve. in addition, machine learning algorithms are used to categorize images after being trained on human-classified examples of the morphological classes. leveraging the strengths of both classification methods, we create a combined method with the aim of improving the efficiency and accuracy of each individual classifier. the resulting classification and characterization should help ligo scientists to identify causes of glitches and subsequently eliminate them from the data or the detector entirely, thereby improving the rate and accuracy of gravitational-wave observations. we demonstrate these methods using a small subset of data from ligo’s first observing run. | gravity spy: integrating advanced ligo detector characterization, machine learning, and citizen science |
we present numerical solutions of several spacetimes of physical interest, including binary black hole mergers, in shift-symmetric einstein-scalar-gauss-bonnet (esgb) gravity, and describe our methods for solving the full equations of motion, without approximation, for general spacetimes. while we concentrate on the specific example of shift-symmetric esgb, our methods, which make use of a recently proposed modification to the generalized harmonic formulation, should be generally applicable to all horndeski theories of gravity (including general relativity). we demonstrate that these methods can stably follow the formation of scalar clouds about initially vacuum nonspinning and spinning black holes for values of the gauss-bonnet coupling approaching the maximum value above which the hyperbolicity of the theory breaks down in spherical symmetry. we study the collision of black holes with scalar hair, finding that the theory remains hyperbolic in the spacetime region exterior to the black hole horizons in a similar regime, which includes cases where the deviations from general relativity in the gravitational radiation is appreciable. finally, we demonstrate that these methods can be used to follow the inspiral and merger of binary black holes in full esgb gravity. this allows for making predictions for horndeski theories of gravity in the strong-field and nonperturbative regime, which can confronted with gravitational wave observations, and compared to approximate treatments of modifications to general relativity. | evolution of einstein-scalar-gauss-bonnet gravity using a modified harmonic formulation |
the next generation of gravitational-wave observatories can explore a wide range of fundamental physics phenomena throughout the history of the universe. these phenomena include access to the universe's binary black hole population throughout cosmic time, to the universe's expansion history independent of the cosmic distance ladders, to stochastic gravitational-waves from early-universe phase transitions, to warped space-time in the strong-field and high-velocity limit, to the equation of state of nuclear matter at neutron star and post-merger densities, and to dark matter candidates through their interaction in extreme astrophysical environments or their interaction with the detector itself. we present the gravitational-wave detector concepts than can drive the future of gravitational-wave astrophysics. we summarize the status of the necessary technology, and the research needed to be able to build these observatories in the 2030s. | snowmass2021 cosmic frontier white paper: future gravitational-wave detector facilities |
intermediate-mass black holes (imbhs) span the approximate mass range 100−105 m⊙, between black holes (bhs) that formed by stellar collapse and the supermassive bhs at the centers of galaxies. mergers of imbh binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. searches of the first two observing runs of advanced ligo and advanced virgo did not yield any significant imbh binary signals. in the third observing run (o3), the increased network sensitivity enabled the detection of gw190521, a signal consistent with a binary merger of mass ∼150 m⊙ providing direct evidence of imbh formation. here, we report on a dedicated search of o3 data for further imbh binary mergers, combining both modeled (matched filter) and model-independent search methods. we find some marginal candidates, but none are sufficiently significant to indicate detection of further imbh mergers. we quantify the sensitivity of the individual search methods and of the combined search using a suite of imbh binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. our most stringent limit is for equal mass and aligned spin bh binary of total mass 200 m⊙ and effective aligned spin 0.8 at 0.056 gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous ligo-virgo limits. we also update the estimated rate of mergers similar to gw190521 to 0.08 gpc−3 yr−1. | search for intermediate-mass black hole binaries in the third observing run of advanced ligo and advanced virgo |
through numerical simulations of boson-star head-on collisions, we explore the quality of binary initial data obtained from the superposition of single-star spacetimes. our results demonstrate that evolutions starting from a plain superposition of individual boosted boson-star spacetimes are vulnerable to significant unphysical artefacts. for equal-mass binaries, these difficulties can be overcome with a simple modification of the initial data suggested in helfer et al (2019 phys. rev. d 99 044046) for collisions of oscillations. while we specifically consider massive complex scalar field boson star models of very high and low compactness, we conjecture that this vulnerability be also present in other kinds of exotic compact systems and hence needs to be addressed. | malaise and remedy of binary boson-star initial data |
we generalise the kosower-maybee-o'connell (kmoc) formalism relating classical observables and scattering amplitudes to curved backgrounds. we show how to compute the final semiclassical state for a particle moving in a curved background in terms of scattering amplitudes on that background. two-point amplitudes in this framework correspond to conservative physics with background-dependent memory effects. as an application, we consider plane wave and shock wave backgrounds both in electromagnetism and general relativity. we determine the final semiclassical state, showing it satisfies a notion of double copy on curved backgrounds. we then conclude by computing the impulse of a particle on such backgrounds, deriving exact results and velocity memory effects. | classical physics from amplitudes on curved backgrounds |
gravitational wave detection requires an in-depth understanding of the physical properties of gravitational wave signals, and the noise from which they are extracted. understanding the statistical properties of noise is a complex endeavor, particularly in realistic detection scenarios. in this article we demonstrate that deep learning can handle the non-gaussian and non-stationary nature of gravitational wave data, and showcase its application to denoise the gravitational wave signals generated by the binary black hole mergers gw150914, gw170104, gw170608 and gw170814 from advanced ligo noise. to exhibit the accuracy of this methodology, we compute the overlap between the time-series signals produced by our denoising algorithm, and the numerical relativity templates that are expected to describe these gravitational wave sources, finding overlaps o ≳ 0.99. we also show that our deep learning algorithm is capable of removing noise anomalies from numerical relativity signals that we inject in real advanced ligo data. we discuss the implications of these results for the characterization of gravitational wave signals. | gravitational wave denoising of binary black hole mergers with deep learning |
active galactic nuclei (agns) are powered by geometrically thin accretion disks surrounding a central supermassive black hole. here we explore the evolution of stars embedded in these extreme astrophysical environments (agn stars). because agn disks are much hotter and denser than most components of the interstellar medium, agn stars are subject to very different boundary conditions than normal stars. they are also strongly affected by both mass accretion, which can run away given the vast mass of the disk, and mass loss due to super-eddington winds. moreover, chemical mixing plays a critical role in the evolution of these stars by allowing fresh hydrogen accreted from the disk to mix into their cores. we find that, depending on the local agn density and sound speed and the duration of the agn phase, agn stars can rapidly become very massive (m > 100 m⊙). these stars undergo core collapse, leave behind compact remnants, and contribute to polluting the disk with heavy elements. we show that the evolution of agn stars can have a profound impact on the evolution of agn metallicities, as well as the production of gravitational wave sources observed by ligo-virgo. we point to our galactic center as a region well suited to testing some of our predictions for this exotic stellar evolutionary channel. | stellar evolution in agn disks |
we construct an inspiral-merger-ringdown eccentric gravitational-wave (gw) model for binary black holes with non-precessing spins within the effective-one-body formalism. this waveform model, seobnrv4ehm, extends the accurate quasi-circular seobnrv4hm model to eccentric binaries by including recently computed eccentric corrections up to 2pn order in the gravitational waveform modes, notably the (l ,|m |)=(2 ,2 ),(2 ,1 ),(3 ,3 ),(4 ,4 ),(5 ,5 ) multipoles. the waveform model reproduces the zero eccentricity limit with an accuracy comparable to the underlying quasicircular model, with the unfaithfulness of ≲1 % against quasicircular numerical-relativity (nr) simulations. when compared against 28 public eccentric nr simulations from the simulating extreme spacetimes catalog with initial orbital eccentricities up to e ≃0.3 and dimensionless spin magnitudes up to +0.7 , the model provides unfaithfulness <1 %, showing that both the (2 ,|2 |)-modes and the higher-order modes are reliably described without calibration to nr datasets in the eccentric sector. the waveform model seobnrv4ehm is able to qualitatively reproduce the phenomenology of dynamical captures, and can be extended to include spin-precession effects. it can be employed for upcoming observing runs with the ligo-virgo-kagra detectors and used to re-analyze existing gw catalogs to infer the eccentricity parameters for binaries with e ≲0.3 (at 20 hz or lower) and spins up to ≲0.9 - 0.95 . the latter is a promising region of the parameter space where some astrophysical formation scenarios of binaries predict mild eccentricity in the ground-based detectors' bandwidth. assessing the accuracy and robustness of the eccentric waveform model seobnrv4ehm for larger eccentricities and spins will require comparisons with, and, likely, calibration to eccentric nr waveforms in a larger region of the parameter space. | effective-one-body multipolar waveforms for eccentric binary black holes with nonprecessing spins |
applying an equation of state (eos) with its symmetric nuclear matter contribution and low-density symmetry energy esym(ρ) constrained by heavy-ion reaction data, we calculate the dimensionless tidal deformability λ of neutron stars in coalescing binary systems. corresponding to the partially constrained eos that previously predicted a radius of 11.5 km ≤{r}_{1.4}r 1.4 ≤ 13.6 km for canonical neutron-star configurations, λ is found to be in the range of 292 ≤{{lambda }}_{1.4}λ 1.4 ≤ 680, consistent with the very recent observation of the gw170817 event. we investigate the effect of the high-density behavior of esym(ρ) on the tidal properties of neutron stars and find that while λ depends strongly on the details of the symmetry energy, different trends of esym(ρ) lead to very similar values of λ. in particular, the transition from stiff/soft-to-soft/stiff esym(ρ) could yield the same λ. thus, measuring λ alone may not determine completely the density dependence of the symmetry energy. coherent analyses of the dense neutron-rich nuclear matter eos underlying both nuclear laboratory experiments and astrophysical observations are therefore necessary to break this degeneracy and determine precisely the details of the esym(ρ). | imprints of the nuclear symmetry energy on the tidal deformability of neutron stars |
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