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mergers of binary black holes on eccentric orbits are among the targets for second-generation ground-based gravitational-wave detectors. these sources may commonly form in galactic nuclei due to gravitational-wave emission during close flyby events of single objects. we determine the distributions of initial orbital parameters for a population of these gravitational-wave sources. our results show that the initial dimensionless pericenter distance systematically decreases with the binary component masses and the mass of the central supermassive black hole, and its distribution depends sensitively on the highest possible black hole mass in the nuclear star cluster. for a multi-mass black hole population with masses between 5 {m}⊙and 80 {m}⊙ , we find that between ∼43-69% (68-94%) of 30 {m}⊙ -30 {m}⊙(10 m ⊙-10 m ⊙) sources have an eccentricity greater than 0.1 when the gravitational-wave signal reaches 10 hz, but less than ∼10% of the sources with binary component masses less than 30 {m}⊙remain eccentric at this level near the last stable orbit (lso). the eccentricity at lso is typically between 0.005-0.05 for the lower-mass bhs, and 0.1-0.2 for the highest-mass bhs. thus, due to the limited low-frequency sensitivity, the six currently known quasicircular ligo/virgo sources could still be compatible with this originally highly eccentric source population. however, at the design sensitivity of these instruments, the measurement of the eccentricity and mass distribution of merger events may be a useful diagnostic to identify the fraction of gw sources formed in this channel. | eccentric black hole gravitational-wave capture sources in galactic nuclei: distribution of binary parameters |
we investigate the capability of various configurations of the space interferometer elisa to probe the late-time background expansion of the universe using gravitational wave standard sirens. we simulate catalogues of standard sirens composed by massive black hole binaries whose gravitational radiation is detectable by elisa, and which are likely to produce an electromagnetic counterpart observable by future surveys. the main issue for the identification of a counterpart resides in the capability of obtaining an accurate enough sky localisation with elisa. this seriously challenges the capability of four-link (2 arm) configurations to successfully constrain the cosmological parameters. conversely, six-link (3 arm) configurations have the potential to provide a test of the expansion of the universe up to z ~ 8 which is complementary to other cosmological probes based on electromagnetic observations only. in particular, in the most favourable scenarios, they can provide a significant constraint on h0 at the level of 0.5%. furthermore, (ωm, ωλ) can be constrained to a level competitive with present snia results. on the other hand, the lack of massive black hole binary standard sirens at low redshift allows to constrain dark energy only at the level of few percent. | science with the space-based interferometer elisa. iii: probing the expansion of the universe using gravitational wave standard sirens |
we develop the foundations of an effective-one-body (eob) model for eccentric binary coalescences that includes the conservative dynamics, radiation reaction, and gravitational waveform modes from the inspiral and the merger-ringdown signals. our approach uses the strategy that is commonly employed in black-hole perturbation theory: we introduce an efficient, relativistic parameterization of the dynamics that is defined by the orbital geometry and consists of a set of phase variables and quantities that evolve only due to gravitational radiation reaction. specializing to nonspinning binaries, we derive the eob equations of motion for the new variables and make use of the fundamental frequencies of the motion to compute the binary's radiative multipole moments that determine the gravitational waves. our treatment has several advantages over the quasi-keplerian approach that is often used in post-newtonian (pn) calculations: a smaller set of variables, parameters that reflect the features of strong-field dynamics, and a greater transparency of the calculations when using the fundamental frequencies that leads to simplifications and an unambiguous orbit-averaging operation. while our description of the conservative dynamics is fully relativistic, we limit explicit derivations in the radiative sector to 1.5pn order for simplicity. this already enables us to establish methods for computing both instantaneous and hereditary contributions to the gravitational radiation in eob coordinates that have straightforward extensions to higher pn order. the weak-field, small eccentricity limit of our results for the orbit-averaged fluxes agrees with known pn results when expressed in terms of gauge-invariant quantities. we further address considerations for the numerical implementation of the model and the completion of the waveforms to include the merger and ringdown signals, and provide illustrative results. | foundations of an effective-one-body model for coalescing binaries on eccentric orbits |
we consider the possibility that the majority of dark matter in our universe consists of black holes of primordial origin. we determine the conditions under which such black holes may have originated from a single-field model of inflation characterized by a quartic polynomial potential. we also explore the effect of higher-dimensional operators. the large power spectrum of curvature perturbations that is needed for a large black hole abundance sources sizable second order tensor perturbations. the resulting stochastic background of primordial gravitational waves could be detected by the future space-based observatories lisa and decigo or—as long as we give up on the dark matter connection—by the ground-based advanced ligo-virgo detector network. | primordial black holes as dark matter and gravitational waves from single-field polynomial inflation |
discrepant measurements of the universe's expansion rate (h0) may signal physics beyond the standard cosmological model. here i describe two early modified gravity mechanisms that reconcile h0 value by increasing the expansion rate in the era of matter-radiation equality. these mechanisms, based on viable horndeski theories, require significantly less fine-tuned initial conditions than early dark energy with oscillating scalar fields. in imperfect dark energy at equality (idee), the initial energy density dilutes slower than radiation but faster than matter, naturally peaking around the era of equality. the minimal idee model, a cubic galileon, is too constrained by the cosmic microwave background (planck) and baryon acoustic oscillations (bao) to relieve the h0 tension. in enhanced early gravity (eeg), the scalar field value modulates the cosmological strength of gravity. the minimal eeg model, an exponentially coupled cubic galileon, gives a planck +bao value h0=68.7 ±1.5 (68% cl), reducing the tension with sh0es from 4.4 σ to 2.6 σ . additionally, galileon contributions to cosmic acceleration may reconcile h0 via late-universe phantom expansion (lupe). combining lupe, eeg and λ reduces the tension between planck, bao, and sh0es to 2.5 σ . i will also describe additional tests of coupled galileons based on local gravity tests, primordial element abundances and gravitational waves. while further model building is required to fully resolve the h0 problem and satisfy all available observations, these examples show the wealth of possibilities to solve cosmological tensions beyond einstein's general relativity. | gravity in the era of equality: towards solutions to the hubble problem without fine-tuned initial conditions |
i review the effective field theory (eft) description of gravitating compact objects. the focus is on kinematic regimes where gravity is perturbative, in particular the adiabatic inspiral phase relevant to gravitational wave detection. for such configurations, there is a hierarchy of length scales which all play a role in the dynamics, ranging from the gravitational radius, to the size of the objects, to their typical orbital separation, and finally the wavelength of the radiation emitted by the system. to disentangle these scales, and to achieve manifest power counting in the expansion parameter, it is necessary to construct a tower of efts of gravity, each coupled to distinct line defect localized degrees of freedom. i describe the relevant effective theories at each scale as well as the matching between these theories across each physical threshold. while the main applications of these methods are to classical dynamics, quantum gravity effects, e.g. hawking graviton exchange, can be systematically incorporated if the momentum transfers are small compared to the planck mass. | effective field theory for compact binary dynamics |
general relativity (gr) was proven via the direct detection of gravitational waves from the mergers of the binary black holes and binary neutron stars by the advanced ligo and advanced virgo detectors. these detections confirmed the prediction of gr and provided the first direct evidence of the existence of stellar-mass black holes (bhs). however, the occurrence of singularities at the centers of bhs suggests that gr is inapplicable because of the breakdown of the equivalence principle at the singularities. the fact that these singularities exist indicates that gr cannot be a universal theory of space-time. in the low-energy limit, the theoretical and observational challenges faced by the λ cdm model also indicate that we might have to look beyond gr as the underlying theory of gravity. unlike gr, whose field equations contain only up to second-order derivatives, the modified theories with higher derivative ricci/riemann tensor gravity models include higher derivatives. therefore, one expects significant differences between gr and modified theories. since there are many ways of modifying gr in the strong-gravity and cosmological distances, each model has unique features. this leads to the following crucial question: are there a set of unique signatures that distinguish gr from modified gravity (mg) theories? this review discusses three aspects of mg theories: (1) why do we need to consider mg theories? (2) how to modify gr? and (3) what are the observational consequences? the review is written in a pedagogical style with the expectation that it will serve as a useful reference for theorists and observers and those interested in bridging the divide between theory and observations. | modified theories of gravity: why, how and what? |
the single-flavor excluded-volume model based on the effective size of baryons reproduces the hard-soft density evolution of the equation of state (eos) required by the recent studies of gw170817. this phenomenological model basically realizes the concept of quarkyonic matter which is introduced from large-nc gauge theory for dense matter. enhanced nucleon interactions and dynamically generated quark degrees of freedom can reproduce the hard-soft evolution of the eos. in this paper, we extend the excluded-volume model to a three-flavor system by considering electromagnetic charge and possible weak equilibrium in order to obtain a proper description for the hard-soft behavior of the eos inferred from the gravitational waves observations. | excluded-volume model for quarkyonic matter: three-flavor baryon-quark mixture |
the milky way and a significant fraction of galaxies are observed to host a central massive black hole (mbh) embedded in a non-spherical nuclear star cluster. we study the secular orbital evolution of compact-object binaries in these environments and characterize the excitation of extremely large eccentricities that can lead to mergers by gravitational radiation. we find that the eccentricity excitation occurs most efficiently when the nodal precession timescale of the binary’s orbit around the mbh due to the non-spherical cluster becomes comparable (within a factor of ∼10) to the timescale on which the binary is torqued by the mbh due to the lidov-kozai (lk) mechanism. we show that in this regime the perturbations due to the cluster increase the fraction of systems that reach extreme eccentricities (1{--}e∼ {10}-4{--}{10}-6) by a factor of ∼10-100 compared to the idealized case of a spherical cluster, increasing the merger rates of compact objects by a similar factor. we identify two main channels that lead to this extreme eccentricity excitation: (i) chaotic diffusion of the eccentricities due to resonance overlap; (ii) cluster-driven variations of the mutual inclinations between the binary orbit and its center-of-mass orbit around the mbh, which can intensify the lk oscillations. we estimate that our mechanism can produce bh-bh and bh-neutron star binary merger rates of up to ≈ 15 {{gpc}}-3 {{yr}}-1 and ≈ 0.4 {{gpc}}-3 {{yr}}-1, respectively. thus, we propose the cluster-enhanced lk mechanism as a new channel for the merger of compact-object binaries, competing with scenarios that invoke isolated binary evolution or dynamical formation in globular clusters. | greatly enhanced merger rates of compact-object binaries in non-spherical nuclear star clusters |
we resolve the potential-restriction problem in k/g inflation by introducing nonminimal coupling. in this context, higgs field successfully drives inflation satisfying cmb observations while enhancing curvature perturbations at small scales, which in turn accounts for primordial black holes (pbhs) and scalar induced gravitational waves (sigws). we then uncover the effect of the non-canonical kinetic coupling function in more detail and study its the observational constraint. besides, we also give the gauge invariant expression for the integral kernel of sigws, which is related to terms propagating with the speed of light. finally, the non-gaussian effect on pbh abundance and sigws is studied. we find that non-gaussianity makes pbhs form more easily, but its effect on the energy density of sigws is negligible. | primordial black holes and scalar induced gravitational waves from higgs inflation with non-canonical kinetic term |
seismic anisotropy records past and present tectonic deformations and provides important constraints for understanding the structure and dynamics of the earth's interior. in this work, we use tremendous amounts of high-quality p wave arrival times from local and regional earthquakes to determine a high-resolution tomographic model of 3-d p wave azimuthal anisotropy down to 1,000-km depth beneath east asia. our results show that trench-parallel fast-velocity directions (fvds) are visible in the shallow portion of the subducting pacific slab (<80 km), whereas the deeper portion of the pacific slab mainly exhibits trench-normal fvds, except for the stagnant slab in the mantle transition zone (mtz) where obvious ne-sw fvds are revealed. the fvds in the subslab mantle change from a subduction-parallel trend at depths of 80-400 km to a subduction-normal trend in the mtz. large-scale low-velocity anomalies are revealed beneath the philippine sea plate where the fvd is ne-sw. the fvds along the izu-bonin arc and in a slab gap exhibit a striking anticlockwise toroidal trend. all these features may reflect complex 3-d flows in the mantle wedge due to tearing and dehydration processes of the subducting pacific slab. the subducting pacific slab is split at 300-km depth under the bonin arc and then penetrates into the lower mantle, whereas under east asia the pacific slab becomes stagnant in the mtz and reaches the north-south gravity lineament in china. the intraplate volcanoes in east asia are caused by hot and wet upwelling flows in the big mantle wedge above the stagnant pacific slab. | mantle dynamics of western pacific and east asia: new insights from p wave anisotropic tomography |
we investigate the klein-gordon quantum oscillator in a global monopole space-time with three versions of rainbow gravity. we solve the related klein-gordon equation analytically and thus find the wave-functions and their corresponding energy eigenvalues. our solutions allow us to assess the physical effect of the three rainbow functions on the global monopole's metric. | klein-gordon oscillator in a global monopole space-time with rainbow gravity |
we study the connection between many-body quantum chaos and energy dynamics for the holographic theory dual to the kerr-ads black hole. in particular, we determine a partial differential equation governing the angular profile of gravitational shock waves that are relevant for the computation of out-of-time ordered correlation functions (otocs). further we show that this shock wave profile is directly related to the behaviour of energy fluctuations in the boundary theory. in particular, we demonstrate using the teukolsky formalism that at complex frequency ω∗ = i2πt there exists an extra ingoing solution to the linearised einstein equations whenever the angular profile of metric perturbations near the horizon satisfies this shock wave equation. as a result, for metric perturbations with such temporal and angular profiles we find that the energy density response of the boundary theory exhibit the signatures of "pole-skipping" — namely, it is undefined, but exhibits a collective mode upon a parametrically small deformation of the profile. additionally, we provide an explicit computation of the otoc in the equatorial plane for slowly rotating large black holes, and show that its form can be used to obtain constraints on the dispersion relations of collective modes in the dual cft. | dual-channel 1.5 mb/s lightwave receiver employing an ingaasp wavelength-demultiplexing detector |
up to now several gravitational-wave events from the coalescences of black hole binaries have been reported by ligo/virgo, and imply that black holes should have an extended mass function. we work out the merger rate distribution of primordial black hole (pbh) binaries with a general mass function by taking into account the torques by all pbhs and linear density perturbations. in the future, many more coalescences of black hole binaries are expected to be detected, and the one-dimensional and two-dimensional merger rate distributions will be crucial for reconstructing the mass function of pbhs. | merger rate distribution of primordial black hole binaries |
particular couplings between a scalar field and the gauss-bonnet invariant lead to spontaneous scalarization of black holes. here, we continue our work on simulating this phenomenon in the context of binary black hole systems. we consider a negative coupling for which the black-hole spin plays a major role in the scalarization process. we find two main phenomena: (i) dynamical descalarization, in which initially scalarized black holes form an unscalarized remnant, and (ii) dynamical scalarization, whereby the late merger of initially unscalarized black holes can cause scalar hair to grow. an important consequence of the latter case is that modifications to the gravitational waveform due to the scalar field may only occur postmerger, as its presence is hidden during the entirety of the inspiral. however, with a sufficiently strong coupling, we find that scalarization can occur before the remnant has even formed. we close with a discussion of observational implications for gravitational-wave tests of general relativity. | spin-induced dynamical scalarization, descalarization, and stealthness in scalar-gauss-bonnet gravity during a black hole coalescence |
we systematically performed numerical-relativity simulations for black hole-neutron star (bh-ns) binary mergers with a variety of the bh spin orientation and nuclear-theory-based equations of state (eos) of the ns. the initial misalignment angles of the bh spin measured from the direction of the orbital angular momentum are chosen in the range of itilt,0≈30 ° -90 ° . we employed four models of nuclear-theory-based zero-temperature eos for the ns in which the compactness of the ns is in the range of c =mns/rns=0.138 -0.180 , where mns and rns are the mass and the radius of the ns, respectively. the mass ratio of the bh to the ns, q =mbh/mns , and the dimensionless spin parameter of the bh, χ , are chosen to be q =5 and χ =0.75 , together with mns=1.35 m⊙ so that the bh spin misalignment has a significant effect on tidal disruption of the ns. we obtain the following results: (i) the inclination angles of itilt,0<70 ° and itilt,0<50 ° are required for the formation of a remnant disk with its mass larger than 0.1 m⊙ for the cases c =0.140 and c =0.160 , respectively, while the disk mass is always smaller than 0.1 m⊙ for c ≳0.175 . the ejecta with its mass larger than 0.01 m⊙ is obtained for itilt,0<85 ° with c =0.140 , for itilt,0<65 ° with c =0.160 , and for itilt,0<30 ° with c =0.175 . (ii) the rotational axis of the dense part of the remnant disk with its rest-mass density larger than 109 g /cm3 is approximately aligned with the remnant bh spin for itilt,0≈30 ° . on the other hand, the disk axis is misaligned initially with ∼30 ° for itilt,0≈60 ° , and the alignment with the remnant bh spin is achieved at ∼50 - 60 ms after the onset of merger. the accretion time scale of the remnant disk is typically ∼100 ms and depends only weakly on the misalignment angle and the eos. (iii) the ejecta velocity is typically ∼0.2 - 0.3 c and depends only weakly on the misalignment angle and the eos of the ns, while the morphology of the ejecta depends on its mass. (iv) the gravitational-wave spectra contains the information of the ns compactness in the cutoff frequency for itilt,0≲60 ° . | black hole-neutron star binary merger: dependence on black hole spin orientation and equation of state |
we derive an effective potential for binary black hole (bbh) spin precession at second post-newtonian order. this effective potential allows us to solve the orbit-averaged spin-precession equations analytically for arbitrary mass ratios and spins. these solutions are quasiperiodic functions of time: after a fixed period, the bbh spins return to their initial relative orientations and jointly precess about the total angular momentum by a fixed angle. using these solutions, we classify bbh spin precession into three distinct morphologies between which bbhs can transition during their inspiral. we also derive a precession-averaged evolution equation for the total angular momentum that can be integrated on the radiation-reaction time and identify a new class of spin-orbit resonances that can tilt the direction of the total angular momentum during the inspiral. our new results will help efforts to model and interpret gravitational waves from generic bbh mergers and predict the distributions of final spins and gravitational recoils. | effective potentials and morphological transitions for binary black hole spin precession |
the recent discovery of gravitational waves from mergers of ∼10 m⊙ black hole binaries has stimulated interested in primordial black hole (pbh) dark matter in this mass range. microlensing and dynamical constraints exclude all of the dark matter in compact objects with a delta function mass function in the range 10-7≲m /m⊙≲1 05 . however it has been argued that all of the dark matter could be composed of compact objects in this range with an extended mass function. we explicitly recalculate the microlensing and dynamical constraints for compact objects with an extended mass function which replicates the pbh mass function produced by inflation models. we find that the microlensing and dynamical constraints place conflicting constraints on the width of the mass function, and do not find a mass function which satisfies both constraints. | microlensing and dynamical constraints on primordial black hole dark matter with an extended mass function |
the theory for single stellar evolution predicts a gap in the mass distribution of black holes (bhs) between approximately 45 and 130 $\,{m}_{\odot }$ , the so-called "pair-instability mass gap." we examine whether bhs can pollute the gap after accreting from a stellar companion. to this end, we simulate the evolution of isolated binaries using a population synthesis code, where we allow for super-eddington accretion. under our most extreme assumptions, we find that at most about 2% of all merging binary bh systems contains a bh with a mass in the pair-instability mass gap, and we find that less than 0.5% of the merging systems has a total mass larger than 90 $\,{m}_{\odot }$ . we find no merging binary bh systems with a total mass exceeding 100 $\,{m}_{\odot }$ . we compare our results to predictions from several dynamical pathways to pair-instability mass gap events and discuss the distinguishable features. we conclude that the classical isolated binary formation scenario will not significantly contribute to the pollution of the pair-instability mass gap. the robustness of the predicted mass gap for the isolated binary channel is promising for the prospective of placing constraints on (i) the relative contribution of different formation channels, (ii) the physics of the progenitors including nuclear reaction rates, and, tentatively, (iii) the hubble parameter. | polluting the pair-instability mass gap for binary black holes through super-eddington accretion in isolated binaries |
the direct observation of gravitational waves with advanced ligo and advanced virgo offers novel opportunities to test general relativity in strong-field, highly dynamical regimes. one such opportunity is the measurement of gravitational-wave polarizations. while general relativity predicts only two tensor gravitational-wave polarizations, general metric theories of gravity allow for up to four additional vector and scalar modes. the detection of these alternative polarizations would represent a clear violation of general relativity. the ligo-virgo detection of the binary black hole merger gw170814 has recently offered the first direct constraints on the polarization of gravitational waves. the current generation of ground-based detectors, however, is limited in its ability to sensitively determine the polarization content of transient gravitational-wave signals. observation of the stochastic gravitational-wave background, in contrast, offers a means of directly measuring generic gravitational-wave polarizations. the stochastic background, arising from the superposition of many individually unresolvable gravitational-wave signals, may be detectable by advanced ligo at design sensitivity. in this paper, we present a bayesian method with which to detect and characterize the polarization of the stochastic background. we explore prospects for estimating parameters of the background and quantify the limits that advanced ligo can place on vector and scalar polarizations in the absence of a detection. finally, we investigate how the introduction of new terrestrial detectors like advanced virgo aid in our ability to detect or constrain alternative polarizations in the stochastic background. we find that, although the addition of advanced virgo does not notably improve detection prospects, it may dramatically improve our ability to estimate the parameters of backgrounds of mixed polarization. | polarization-based tests of gravity with the stochastic gravitational-wave background |
we give a brief review of the history of inflationary theory and then concentrate on the recently discovered set of inflationary models called cosmological α-attractors. these models provide an excellent fit to the latest observational data. their predictions ns ≈ 1 - 2 / n and r ≈ 12 α /n2 are very robust with respect to the modifications of the inflaton potential. an intriguing interpretation of α-attractors is based on a geometric moduli space with a boundary: a poincaré disk model of a hyperbolic geometry with the radius √{ 3 α }, beautifully represented by the escher's picture circle limit iv. in such models, the amplitude of the gravitational waves is proportional to the square of the radius of the poincaré disk. xml:lang="fr" | escher in the sky |
strong gravitational lensing of gravitational waves can produce duplicate signals separated in time with different amplitudes. we consider the case in which strong lensing produces superthreshold gravitational-wave events and weaker subthreshold signals buried in the noise background. we present the gstlal-based targeted subthreshold lensing search search method for the subthreshold signals using reduced template banks targeting specific confirmed gravitational-wave events. we perform a simulation campaign to assess the performance of the proposed search method. we show that it can effectively uprank potential subthreshold lensed counterparts to the target gravitational-wave event. we also compare its performance to other alternative solutions to the posed problem and demonstrate that our proposed method outperforms the other solutions. the method described in this paper has already been deployed in the recent lvk collaboration-wide search for lensing signatures of gravitational waves in the first half of ligo/virgo third observing run o3a [r. abbott et al. (ligo scientific, virgo collaborations), astrophys. j. 923, 14 (2021)., 10.3847/1538-4357/ac23db]. | targeted subthreshold search for strongly lensed gravitational-wave events |
we study gravity wave production and baryogenesis at the electroweak phase transition, in a real singlet scalar extension of the standard model, including vector-like top partners to generate the cp violation needed for electroweak baryogenesis (ewbg). the singlet makes the phase transition strongly first-order through its coupling to the higgs boson, and it spontaneously breaks cp invariance through a dimension-5 contribution to the top quark mass term, generated by integrating out the heavy top quark partners. we improve on previous studies by incorporating updated transport equations, compatible with large bubble wall velocities. the wall speed and thickness are computed directly from the microphysical parameters rather than treating them as free parameters, allowing for a first-principles computation of the baryon asymmetry. the size of the cp-violating dimension-5 operator needed for ewbg is constrained by collider, electroweak precision, and renormalization group running constraints. we identify regions of parameter space that can produce the observed baryon asymmetry or observable gravitational (gw) wave signals. contrary to standard lore, we find that for strong deflagrations, the efficiencies of large baryon asymmetry production and strong gw signals can be positively correlated. however we find the overall likelihood of observably large gw signals to be smaller than estimated in previous studies. in particular, only detonation-type transitions are predicted to produce observably large gravitational waves. | baryogenesis and gravity waves from a uv-completed electroweak phase transition |
in this paper i discuss how to consistently incorporate higher-order corrections to the bubble-nucleation rate at finite temperature. doing so i examine the merits of different approaches, with the goal of reducing uncertainties for gravitational-wave calculations. to be specific, the region of applicability and accuracy of the derivative expansion is discussed. the derivative expansion is then compared to a numerical implementation of the gelfand-yaglom theorem. both methods are applied to popular first-order phase transition models, like a loop-induced barrier and a sm-eft tree-level barrier. the results of these calculations are presented in easy-to-use parametrizations that can directly be used in gravitational-wave calculations. in addition, higher-order corrections for models with multiple scalar fields, such as singlet/triplet extensions, are studied. lastly, the main goal of this paper is to investigate the convergence and uncertainty of all calculation. doing so i argue that current calculations for the standard model with a tree-level barrier are inaccurate. | higher-order corrections to the bubble-nucleation rate at finite temperature |
we expand on the known result that the carroll algebra in 2 + 1 dimensions admits two non-trivial central extensions by computing the associated lie group, which we call extended carroll group. the symplectic geometry associated to this group is then computed to describe the motion of planar carroll elementary particles, in the free case, when coupled to an electromagnetic field, and to a gravitational field. we compare to the motions of carroll particles in 3 + 1 dimensions in the same conditions, and also give the dynamics of carroll particles with spin. in an electromagnetic background, the planar carroll dynamics differ from the known carroll ones due to 2 new casimir invariants, and turn out to be non-trivial. the coupling to a gravitational field leaves the dynamics trivial, however. finally, we obtain the quantum equation obeyed by carroll wave functions via geometric quantization. | planar carrollean dynamics, and the carroll quantum equation |
with the hundreds of merging binary black hole (bh) signals expected to be detected by laser interferometer gravitational-wave observatory (ligo)/virgo, laser interferometer space antenna (lisa), and other instruments in the next few years, the modelling of astrophysical channels that lead to the formation of compact object binaries has become of fundamental importance. in this paper, we carry out a systematic statistical study of quadruple bhs consisting of two binaries in orbit around their centre of mass, by means of high-precision direct n-body simulations including post-newtonian (pn) terms up to 2.5pn order. we found that most merging systems have high initial inclinations and the distributions peak at ∼90° as for triples, but with a more prominent broad distribution tail. we show that bhs merging through this channel have a significant eccentricity in the ligo band, typically much larger than bhs merging in isolated binaries and in binaries ejected from star clusters, but comparable to that of merging binaries formed via the gravitational wave capture scenario in clusters, mergers in hierarchical triples, or bh binaries orbiting intermediate-mass bhs in star clusters. we show that the merger fraction can be up to ∼3-4× higher for quadruples than for triples. thus even if the number of quadruples is 20-25 per cent of the number of triples, the quadruple scenario can represent an important contribution to the events observed by ligo/virgo. | black hole mergers from quadruples |
in this work we shall develop a quantitative approach for extracting predictions on the primordial gravitational waves energy spectrum for f(r) gravity. we shall consider two distinct models which yield different phenomenology, one pure f(r) gravity model and one chern-simons corrected potential-less k-essence f(r) gravity model in the presence of radiation and non-relativistic perfect matter fluids. the two f(r) gravity models were carefully chosen in order for them to describe in a unified way inflation and the dark energy era, in both cases viable and compatible with the latest planck data. also both models mimic the λ-cold-dark-matter model and specifically the pure f(r) model only at late times, but the chern-simons k-essence model during the whole evolution of the model up to the radiation domination era. in addition they guarantee a smooth transition from the inflationary era to the radiation, matter domination and subsequently to the dark energy era. using a wkb approach introduced in the relevant literature by nishizawa, we derive formulas depending on the redshift that yield the modified gravity effect, quantified by a multiplicative factor, a "damping" in front of the general relativistic waveform. in order to calculate the effect of the modified gravity, which is the "damping" factor, we solve numerically the friedmann equations using appropriate initial conditions and by introducing specific statefinder quantities. as we show, the pure f(r) gravity gravitational wave energy spectrum is slightly enhanced, but it remains well below the sensitivity curves of future gravitational waves experiments. in contrast, the chern-simons k-essence f(r) gravity model gravitational wave energy spectrum is significantly enhanced and two signals are predicted which can be verified by future gravitational wave experiments. we discuss in detail our findings and the future perspective of modified gravity theories in view of the upcoming second and third generation experiments on primordial gravitational waves. | quantitative predictions for f(r) gravity primordial gravitational waves |
large dark matter overdensities can form around black holes of astrophysical and primordial origin as they form and grow. this "dark dress" inevitably affects the dynamical evolution of binary systems and induces a dephasing in the gravitational waveform that can be probed with future interferometers. in this paper, we introduce a new analytical model to rapidly compute gravitational waveforms in the presence of an evolving dark matter distribution. we then present a bayesian analysis determining when dressed black hole binaries can be distinguished from gr-in-vacuum ones and how well their parameters can be measured, along with how close they must be to be detectable by the planned laser interferometer space antenna (lisa). we show that lisa can definitively distinguish dark dresses from standard binaries and characterize the dark matter environments around astrophysical and primordial black holes for a wide range of model parameters. our approach can be generalized to assess the prospects for detecting, classifying, and characterizing other environmental effects in gravitational wave physics. | measuring the dark matter environments of black hole binaries with gravitational waves |
gravitational wave observations of compact binary mergers are already providing stringent tests of general relativity and constraints on modified gravity. ground-based interferometric detectors will soon reach design sensitivity, and they will be followed by third-generation upgrades, possibly operating in conjunction with space-based detectors. how will these improvements affect our ability to investigate fundamental physics with gravitational waves? the answer depends on the timeline for the sensitivity upgrades of the instruments, but also on astrophysical compact binary population uncertainties, which determine the number and signal-to-noise ratio of the observed sources. we consider several scenarios for the proposed timeline of detector upgrades and various astrophysical population models. using a stacked fisher matrix analysis of binary black hole merger observations, we thoroughly investigate future theory-agnostic bounds on modifications of general relativity as well as bounds on specific theories. for theory-agnostic bounds, we find that ground-based observations of stellar-mass black holes and lisa observations of massive black holes can each lead to improvements of 2-4 orders of magnitude with respect to present gravitational wave constraints, while multiband observations can yield improvements of 1-6 orders of magnitude. we also clarify how the relation between theory-agnostic and theory-specific bounds depends on the source properties. | probing fundamental physics with gravitational waves: the next generation |
context. asteroseismology allows us to probe stellar interiors. in the case of red giant stars, conditions in the stellar interior are such as to allow for the existence of mixed modes, consisting in a coupling between gravity waves in the radiative interior and pressure waves in the convective envelope. mixed modes can thus be used to probe the physical conditions in red giant cores. however, we still need to identify the physical mechanisms that transport angular momentum inside red giants, leading to the slow-down observed for red giant core rotation. thus large-scale measurements of red giant core rotation are of prime importance to obtain tighter constraints on the efficiency of the internal angular momentum transport, and to study how this efficiency changes with stellar parameters.aims: this work aims at identifying the components of the rotational multiplets for dipole mixed modes in a large number of red giant oscillation spectra observed by kepler. such identification provides us with a direct measurement of the red giant mean core rotation.methods: we compute stretched spectra that mimic the regular pattern of pure dipole gravity modes. mixed modes with the same azimuthal order are expected to be almost equally spaced in stretched period, with a spacing equal to the pure dipole gravity mode period spacing. the departure from this regular pattern allows us to disentangle the various rotational components and therefore to determine the mean core rotation rates of red giants.results: we automatically identify the rotational multiplet components of 1183 stars on the red giant branch with a success rate of 69% with respect to our initial sample. as no information on the internal rotation can be deduced for stars seen pole-on, we obtain mean core rotation measurements for 875 red giant branch stars. this large sample includes stars with a mass as large as 2.5 m⊙, allowing us to test the dependence of the core slow-down rate on the stellar mass.conclusions: disentangling rotational splittings from mixed modes is now possible in an automated way for stars on the red giant branch, even for the most complicated cases, where the rotational splittings exceed half the mixed-mode spacing. this work on a large sample allows us to refine previous measurements of the evolution of the mean core rotation on the red giant branch. rather than a slight slow-down, our results suggest rotation is constant along the red giant branch, with values independent of the mass. | core rotation braking on the red giant branch for various mass ranges |
we analyse the gravitational wave and low energy signatures of a pati-salam phase transition. for a pati-salam scale of m ps ∼ 105 gev, we find a stochastic power spectrum within reach of the next generation of ground-based interferometer experiments such as the einstein telescope, in parts of the parameter space. we study the lifetime of the proton in this model, as well as complementarity with low energy constraints including electroweak precision data, neutrino mass measurements, lepton flavour violation, and collider constraints. | gravitational waves from a pati-salam phase transition |
we analyze the role played by a mixed vector-isoscalar/vector-isovector meson interaction in dense matter present in the interior of neutron stars in the light of new measurements made during the double neutron-star merger gw170817. these concern measurements of tidal deformability from gravitational waves and electromagnetic observations. our study includes three different equations of state that contain different physical assumptions and matter compositions, namely the nl3 family, many body forces, and chiral mean field models. other related quantities/relations analyzed are the neutron matter pressure, symmetry energy slope, stellar masses and radii, and urca process threshold for stellar cooling. | what do we learn about vector interactions from gw170817? |
we investigate spherical domain walls (dws) nucleated via quantum tunneling in multifield inflationary models and curvature perturbations induced by the inhomogeneous distribution of those dws. we consider the case that the euclidean action se of dws changes with time during inflation so that most dws nucleate when se reaches the minimum value and the radii of dws are almost the same. when the hubble horizon scale exceeds the dw radius after inflation, dws begin to annihilate and release their energy into background radiation. because of the random nature of the nucleation process, the statistics of dws is of the poisson type and the power spectrum of curvature perturbations has a characteristic slope pr(k )∝k3. the amplitude of pr(k ) depends on the tension and abundance of dws at the annihilation time, while the peak mode depends on the mean separation of dws. we also numerically obtain the energy spectra of scalar-induced gravitational waves from predicted curvature perturbations that are expected to be observed in multiband gravitational-wave detectors. | enhanced curvature perturbations from spherical domain walls nucleated during inflation |
pole-skipping is a property of gravitational waves dictated by their behaviour at horizons of black holes. it stems from the inability to unambiguously impose ingoing boundary conditions at the horizon at an infinite discrete set of fourier modes. the phenomenon has been best understood, when such a description exists, in terms of dual holographic (ads/cft) correlation functions that take the value of `0/0' at these special points. in this work, we investigate details of pole-skipping purely from the point of view of classical gravity in 4d massive black hole geometries with flat, spherical and hyperbolic horizons, and with an arbitrary cosmological constant. we show that pole-skipping points naturally fall into two categories: the algebraically special points and a set of pole-skipping points that is common to the even and odd channels of perturbations. our analysis utilises and generalises (to arbitrary maximally symmetric horizon topology and cosmological constant) the `integrable' structure of the darboux transformations, which relate the master field equations that describe the evolution of gravitational perturbations in the two channels. finally, we provide new insights into a number of special cases: spherical black holes, asymptotically anti-de sitter black branes and pole-skipping at the cosmological horizon in de sitter space. | pole-skipping of gravitational waves in the backgrounds of four-dimensional massive black holes |
superconducting cavities can operate analogously to weber bar detectors of gravitational waves, converting mechanical to electromagnetic energy. the significantly reduced electromagnetic noise results in increased sensitivity to high-frequency signals well outside the bandwidth of the lowest mechanical resonance. in this work, we revisit such signals of gravitational waves and demonstrate that a setup similar to the existing mago prototype, operating in a scanning or broadband manner, could have sensitivity to strains of ∼10-22−10-18 for frequencies of ∼10 khz - 1 ghz . | electromagnetic cavities as mechanical bars for gravitational waves |
for the past decade, the bicep/keck collaboration has been operating a series of telescopes at the amundsen-scott south pole station measuring degree-scale $b$-mode polarization imprinted in the cosmic microwave background (cmb) by primordial gravitational waves (pgws). these telescopes are compact refracting polarimeters mapping about 2% of the sky, observing at a broad range of frequencies to account for the polarized foreground from galactic synchrotron and thermal dust emission. our latest publication "bk18" utilizes the data collected up to the 2018 observing season, in conjunction with the publicly available wmap and planck data, to constrain the tensor-to-scalar ratio $r$. it particularly includes (1) the 3-year bicep3 data which is the current deepest cmb polarization map at the foreground-minimum 95 ghz; and (2) the keck 220 ghz map with a higher signal-to-noise ratio on the dust foreground than the planck 353 ghz map. we fit the auto- and cross-spectra of these maps to a multicomponent likelihood model ($\lambda$cdm+dust+synchrotron+noise+$r$) and find it to be an adequate description of the data at the current noise level. the likelihood analysis yields $\sigma(r)=0.009$. the inference of $r$ from our baseline model is tightened to $r_{0.05}=0.014^{+0.010}_{-0.011}$ and $r_{0.05}<0.036$ at 95% confidence, meaning that the bicep/keck $b$-mode data is the most powerful existing dataset for the constraint of pgws. the up-coming bicep array telescope is projected to reach $\sigma(r) \lesssim 0.003$ using data up to 2027. | the latest constraints on inflationary b-modes from the bicep/keck telescopes |
motivated by recent interest in the phenomenon of waves transport in massive stars, we examine whether the heat-driven gravity (g) modes excited in slowly pulsating b (spb) stars can significantly modify the stars' internal rotation. we develop a formalism for the differential torque exerted by g modes, and implement this formalism using the gyre oscillation code and the mesastar stellar evolution code. focusing first on a 4.21m⊙ model, we simulate 1 000 yr of stellar evolution under the combined effects of the torque due to a single unstable prograde g mode (with an amplitude chosen on the basis of observational constraints), and diffusive angular momentum transport due to convection, overshooting, and rotational instabilities. we find that the g mode rapidly extracts angular momentum from the surface layers, depositing it deeper in the stellar interior. the angular momentum transport is so efficient that by the end of the simulation, the initially non-rotating surface layers are spun in the retrograde direction to ≈ 30 per cent of the critical rate. however, the additional inclusion of magnetic stresses in our simulations almost completely inhibits this spin-up. expanding our simulations to cover the whole instability strip, we show that the same general behaviour is seen in all spb stars. after providing some caveats to contextualize our results, we hypothesize that the observed slower surface rotation of spb stars (as compared to other b-type stars) may be the direct consequence of the angular momentum transport that our simulations demonstrate. | angular momentum transport by heat-driven g-modes in slowly pulsating b stars |
in this work, we make the first study of electroweak baryogenesis (ewbg) based on the lhc data in the cp-violating next-to-minimal supersymmetric model (nmssm) where a strongly first order electroweak phase transition (ewpt) is obtained in the general complex higgs potential. with representative benchmark points which pass the current lep and lhc constraints, we demonstrate the structure of ewpt for those points and how a strongly first order ewpt is obtained in the complex nmssm where the resulting gravitational wave production properties are found to be within the reaches of future space-based interferometers like bbo and ultimate-decigo. we further calculate the generated baryon asymmetries where the cp violating sources are (1): higgsino-singlino dominated, (2): higgsino-gaugino dominated or (3): from both sources. it is shown that all three representing scenarios could evade the strong constraints set by various electric dipole moments (edm) searches where cancellations among the edm contributions occur at the tree level (higgsino-singlino dominated) or loop level (higgsino-gaugino dominated). the 125 gev sm like higgs can be either the second lightest neutral higgs h 2 or the third lightest neutral higgs h 3. finally, we comment on the future direct and indirect probe of cpv in the higgs sector from the collider and edm experiments. the work of lgb is supported by the national natural science foundation of china (11605016, 11647307), basic science research program through the national research foundation of korea (nrf) funded by the ministry of education, science and technology (nrf-2016r1a2b4008759), and korea research fellowship program through the national research foundation of korea (nrf) funded by the ministry of science and ict (2017h1d3a1a01014046) | gravitational waves, baryon asymmetry of the universe and electric dipole moment in the cp-violating nmssm |
we present a detailed investigation into the properties of gw170729, the gravitational wave with the most massive and distant source confirmed to date. we employ an extensive set of waveform models, including new improved models that incorporate the effect of higher-order waveform modes which are particularly important for massive systems. we find no indication of spin-precession, but the inclusion of higher-order modes in the models results in an improved estimate for the mass ratio of (0.3 - 0.8 ) at the 90% credible level. our updated measurement excludes equal masses at that level. we also find that models with higher-order modes lead to the data being more consistent with a smaller effective spin, with the probability that the effective spin is greater than zero being reduced from 99% to 94%. the 90% credible interval for the effective spin parameter is now (-0.01 -0.50 ). additionally, the recovered signal-to-noise ratio increases by ∼0.3 units compared to analyses without higher-order modes; the overall bayes factor in favor of the presence of higher-order modes in the data is 5.1 ∶1 . we study the effect of common spin priors on the derived spin and mass measurements, and observe small shifts in the spins, while the masses remain unaffected. we argue that our conclusions are robust against systematic errors in the waveform models. we also compare the above waveform-based analysis which employs compact-binary waveform models to a more flexible wavelet- and chirplet-based analysis. we find consistency between the two, with overlaps of ∼0.9 , typical of what is expected from simulations of signals similar to gw170729, confirming that the data are well-described by the existing waveform models. finally, we study the possibility that the primary component of gw170729 was the remnant of a past merger of two black holes and find this scenario to be indistinguishable from the standard formation scenario. | on the properties of the massive binary black hole merger gw170729 |
third-generation (3g) gravitational-wave detectors will be able to observe binary black hole mergers (bbhs) up to a redshift of ∼30. this gives unprecedented access to the formation and evolution of bbhs throughout cosmic history. in this paper, we consider three subpopulations of bbhs originating from the different evolutionary channels: isolated formation in galactic fields, dynamical formation in globular clusters, and mergers of black holes formed from population iii (pop iii) stars at very high redshift. using input from population synthesis analyses, we create 2 months of simulated data of a network of 3g detectors made of two cosmic explorers and one einstein telescope consisting of ∼16,000 field and cluster bbhs, as well as ∼400 pop iii bbhs. first, we show how one can use a nonparametric model to infer the existence and characteristics of a primary and secondary peak in the merger rate distribution as a function of redshift. in particular, the location and height of the secondary peak around z ≈ 12, arising from the merger of pop iii remnants, can be constrained at the ${ \mathcal o }(10 \% )$ level (95% credible interval). then we perform a modeled analysis using phenomenological templates for the merger rates of the three subpopulations and extract the branching ratios and characteristic parameters of the merger rate densities of the individual formation channels. with this modeled method, the uncertainty on the measurement of the fraction of pop iii bbhs can be improved to ≲10%, while the ratio between field and cluster bbhs can be measured with an uncertainty of ∼100%. | probing multiple populations of compact binaries with third-generation gravitational-wave detectors |
the orbital eccentricity of a merging binary black hole leaves an imprint on the associated gravitational-wave signal that can reveal whether the binary formed in isolation or in a dynamical environment, such as the core of a dense star cluster. we present measurements of the eccentricity of 26 binary black hole mergers in the second ligo-virgo gravitational-wave transient catalog, updating the total number of binary black holes analyzed for orbital eccentricity to 36. using the seobnre waveform, we find the data for gw190620a are poorly explained by the zero-eccentricity hypothesis (frequentist p-value ≲0.1%). using a log-uniform prior on eccentricity, the eccentricity at 10 hz for gw190620a is constrained to e10 ≥ 0.05 (0.1) at 74% (65%) credibility. with this log-uniform prior, we obtain a 90% credible lower eccentricity limit of 0.001, while assuming a uniform prior leads the data to prefer e10 ≥ 0.11 at 90% credibility. this is the second measurement of a binary black hole system with statistical support for nonzero eccentricity; the intermediate-mass black hole merger gw190521 was the first. interpretation of these two events is currently complicated by waveform systematics; we are unable to simultaneously model the effects of relativistic precession and eccentricity. however, if these two events are, in fact, eccentric mergers, then there are potentially many more dynamically assembled mergers in the ligo-virgo catalog without measurable eccentricity; ≳27% of the observed ligo-virgo binaries may have been assembled dynamically in dense stellar environments (95% credibility). | signs of eccentricity in two gravitational-wave signals may indicate a subpopulation of dynamically assembled binary black holes |
theories of quantum gravity based on the holographic principle predict the existence of quantum fluctuations of distance measurements that accumulate and exhibit correlations over macroscopic distances. this paper models an expected signal due to this phenomenology, and details the design and estimated sensitivity of co-located twin table-top 3d interferometers being built to measure or constrain it. the experiment is estimated to be sensitive to displacements $\sim \hspace{-3.5pt}1{0}^{-19}\enspace \mathrm{m}/\sqrt{\mathrm{h}\mathrm{z}}$ in a frequency band between 1 and 250 mhz, surpassing previous experiments and enabling the possible observation of quantum gravity phenomena. the experiment will also be sensitive to mhz gravitational waves and various dark matter candidates. | an experiment for observing quantum gravity phenomena using twin table-top 3d interferometers |
large-eddy simulations (les) have shown the effects of ocean surface gravity waves in enhancing the ocean boundary layer mixing through langmuir turbulence. neglecting this langmuir mixing process may contribute to the common shallow bias in mixed layer depth in regions of the southern ocean and the northern atlantic in most state-of-the-art climate models. in this study, a third generation wave model, wavewatch iii, has been incorporated as a component of the community earth system model, version 1.2 (cesm1.2). in particular, the wave model is now coupled with the ocean model through a modified version of the k-profile parameterization (kpp) to approximate the influence of langmuir mixing. unlike past studies, the wind-wave misalignment and the effects of stokes drift penetration depth are considered through empirical scalings based on the rate of mixing in les. wave-ocean only experiments show substantial improvements in the shallow biases of mixed layer depth in the southern ocean. ventilation is enhanced and low concentration biases of pcfc-11 are reduced in the southern hemisphere. a majority of the improvements persist in the presence of other climate feedbacks in the fully coupled experiments. in addition, warming of the subsurface water over the majority of global ocean is observed in the fully coupled experiments with waves, and the cold subsurface ocean temperature biases are reduced. | langmuir mixing effects on global climate: wavewatch iii in cesm |
we propose that the recently observed quasi-periodic eruptions (qpes) in galactic nuclei are produced by unstable mass transfer due to roche lobe overflow of a low-mass main-sequence star in a mildly eccentric (e ~ 0.5) orbit. we argue that the qpe emission is powered by circularization shocks, but not directly by black hole (bh) accretion. our model predicts the presence of a time-steady accretion disc that is bolometrically brighter than the time-averaged qpe luminosity, but primarily emits in the extreme-ultraviolet. this is consistent with the quiescent soft x-ray emission detected in between the eruptions in erosita qpe1, qpe2, and gsn 069. such accretion discs have an unusual νlν ∝ ν12/7 optical spectrum. the lifetime of the bright qpe phase, 102-103 yr, is set by mass-loss triggered by ram-pressure interaction between the star and the accretion disc fed by the star itself. we show that the stellar orbits needed to explain qpes can be efficiently created by the hills breakup of tight stellar binaries provided that (i) the stellar binary orbit is tidally hardened before the breakup due to diffusive growth of the f-mode amplitude and (ii) the captured star's orbit decays by gravitational wave emission without significant orbital angular momentum diffusion (which is the case for low-mass bhs, mbh ≲ 106 m⊙). we conclude by discussing the implications of our model for hyper-velocity stars, extreme mass ratio inspirals, repeating partial tdes, and related stellar phenomena in galactic nuclei. | quasi-periodic eruptions from mildly eccentric unstable mass transfer in galactic nuclei |
classical subleading soft graviton theorem in four space-time dimensions determines the gravitational wave-form at late and early retarded time, generated during a scattering or explosion, in terms of the four momenta of the ingoing and outgoing objects. this result was `derived' earlier by taking the classical limit of the quantum soft graviton theorem, and making some assumptions about how to deal with the infrared divergences of the soft factor. in this paper we give a direct proof of this result by analyzing the classical equations of motion of gravity coupled to matter. we also extend the result to the electromagnetic wave-form generated during scattering of charged particles, and present a new conjecture on subsubleading corrections to the gravitational wave-form at early and late retarded time. | proof of the classical soft graviton theorem in d = 4 |
light bosonic scalars (e.g., axions) may form clouds around black holes via superradiant instabilities or via accretion if they form some component of the dark matter. it has been suggested that their presence may lead to a distinctive dephasing of the gravitational wave signal when a small compact object spirals into a larger black hole. motivated by this, we study numerically the dynamical friction force on a black hole moving at relativistic velocities in a background scalar field with an asymptotically homogeneous energy density. we show that the relativistic scaling is analogous to that found for supersonic collisional fluids, assuming an approximate expression for the pressure correction which depends on the velocity and scalar mass. while we focus on a complex scalar field, our results confirm the expectation that real scalars would exert a force which oscillates between positive and negative values in time with a frequency set by the scalar mass. the complex field describes the time averaged value of this force, but in a real scalar, the rapid force oscillations could, in principle, leave an imprint on the trajectory. the approximation we obtain can be used to inform estimates of dephasing in the final stages of an extreme mass ratio inspiral. | dynamical friction from scalar dark matter in the relativistic regime |
we present the probability distribution of the systematic errors in the most accurate, high-latency version of the reconstructed dimensionless strain $h$, at the hanford and livingston ligo detectors, used for gravitational-wave astrophysical analysis, including parameter estimation, in the last five months of the third observing run (o3b). this work extends the results presented in sun et. al (2020) [1] for the first six months of the third observing run (o3a). the complex-valued, frequency-dependent, and slowly time-varying systematic error (excursion from unity magnitude and zero phase) in o3b generally remains at a consistent level as in o3a, yet changes of detector configurations in o3b have introduced a non-negligible change in the frequency dependence of the error, leading to larger excursions from unity at some frequencies and/or during some observational periods; in some other periods the excursions are smaller than those in o3a. for o3b, the upper limit on the systematic error and associated uncertainty is 11.29% in magnitude and 9.18 deg in phase (68% confidence interval) in the most sensitive frequency band 20-2000 hz. the systematic error alone is estimated at levels of < 2% in magnitude and $\lesssim 4$ deg in phase. these errors and uncertainties are dominated by the imperfect modeling of the frequency dependence of the detector response functions rather than the uncertainty in the absolute reference, the photon calibrators. | characterization of systematic error in advanced ligo calibration in the second half of o3 |
squeezed light—light with quantum noise lower than shot noise in some quadratures and higher in others—can be used to improve the sensitivity of precision measurements. in particular, squeezed light sources based on nonlinear optical crystals are being used to improve the sensitivity of gravitational wave detectors. in optomechanical squeezers, the radiation-pressure-driven interaction of a coherent light field with a mechanical oscillator induces correlations between the amplitude and phase quadratures of the light, which induce the squeezing. however, thermally driven fluctuations of the mechanical oscillator's position make it difficult to observe the quantum correlations at room temperature and at low frequencies. here, we present a measurement of optomechanically squeezed light, performed at room temperature in a broad band near the audio-frequency regions relevant to gravitational wave detectors. we observe sub-poissonian quantum noise in a frequency band of 30-70 khz with a maximum reduction of 0.7 ± 0.1 db below shot noise at 45 khz. we present two independent methods of measuring this squeezing, one of which does not rely on the calibration of shot noise. | room-temperature optomechanical squeezing |
aims: the dynamics of coalescing compact binaries can be affected by the environment in which the systems evolve, leaving detectable signatures in the emitted gravitational signal. in this paper, we investigate the ability of gravitational-wave detectors to constrain the nature of the environment in which compact binaries merge.methods: we parametrized a variety of environmental effects by modifying the phase of the gravitational signal emitted by black hole and neutron star binaries. we infer the bounds on such effects by current and future generations of interferometers, studying their dependence on the binary's parameters.results: we show that the strong dephasing induced by accretion and dynamical friction can constrain the density of the surrounding medium to orders of magnitude below those of accretion disks. planned detectors, such as lisa or decigo, will be able to probe densities typical of those of dark matter. | constraints on the astrophysical environment of binaries with gravitational-wave observations |
the generalized uncertainty principle and a minimum measurable length arise in various theories of gravity and predict planck-scale modifications of the canonical position-momentum commutation relation. postulating a similar modified commutator between the canonical variables of the electromagnetic field in quantum optics, we compute planck-scale corrections to the radiation pressure noise and shot noise of michelson-morley interferometers, with particular attention to gravity wave detectors such as ligo. we show that advanced ligo is potentially sensitive enough to observe planck-scale effects and thereby indirectly a minimal length. we also propose estimates for the bounds on quantum gravity parameters from current and future advanced ligo experiments. | potential tests of the generalized uncertainty principle in the advanced ligo experiment |
using general-relativistic hydrodynamical simulations, we show that merging binary neutron stars can form hypermassive neutrons stars that undergo the one-arm spiral instability. we study the particular case of a dynamical capture merger where the stars have a small spin, as may arise in globular clusters, and focus on an equal-mass scenario where the spins are aligned with the orbital angular momentum. we find that this instability develops when postmerger fluid vortices lead to the generation of a toroidal remnant—a configuration whose maximum density occurs in a ring around the center-of-mass—with high vorticity along its rotation axis. the instability quickly saturates on a time scale of ∼10 ms , with the m =1 azimuthal density multipole mode dominating over higher modes. the instability also leaves a characteristic imprint on the postmerger gravitational wave signal that could be detectable if the instability persists in long-lived remnants. | one-arm spiral instability in hypermassive neutron stars formed by dynamical-capture binary neutron star mergers |
the advanced virgo detector has contributed with its data to the rapid growth of the number of detected gravitational-wave signals in the past few years, alongside the two 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 about 80 events to the catalog of transient gravitational-wave sources maintained by ligo, virgo and kagra. these discoveries and the manifold exploitation of the detected waveforms require an accurate characterization of the quality of the data, such as continuous study and monitoring of the detector noise. these activities, collectively named {\em detector characterization} or {\em detchar}, span the whole workflow of the virgo data, from the instrument front-end to the final analysis. they are described in details in the following article, with a focus on the associated tools, the results achieved by the virgo detchar group during the o3 run and the main prospects for future data-taking periods with an improved detector. | virgo detector characterization and data quality during the o3 run |
we study the lifetimes of the remnant produced by the merger of two neutron stars and revisit the determination of the threshold mass to prompt collapse, m th. using a fully general-relativistic numerical approach and a novel method for a rigorous determination of m th, we show that a nonlinear universal relation exists between the threshold mass and the maximum compactness. for the temperature-dependent equations of state considered here, our results improve a similar linear relation found recently with methods that are less accurate but yield quantitatively similar results. furthermore, exploiting the information from gw170817, we use the universal relation to set lower limits on the stellar radii for any mass. | a general-relativistic determination of the threshold mass to prompt collapse in binary neutron star mergers |
this study analyzes data obtained by intensive observation during a pilot field campaign of the years of the maritime continent project (pre-ymc) to investigate the diurnal cycle of precipitation in the western coastal area of sumatra island. the diurnal cycle during the campaign period (november-december 2015) is found to have a number of similarities with statistical behavior of the diurnal cycle as revealed by previous studies, such as afternoon precipitation over land, nighttime offshore migration of the precipitation zone, and dependency on madden-julian oscillation (mjo) phase. composite analyses of radiosonde soundings from the research vessel (r/v) mirai, deployed about 50 km off the coast, demonstrate that the lower free troposphere starts cooling in late afternoon (a couple of hours earlier than the cooling in the boundary layer), making the lower troposphere more unstable just before precipitation starts to increase. as the nighttime offshore precipitation tends to be more vigorous on days when the cooling in the lower free troposphere is larger, it is possible that the destabilization due to the cooling contributes to the offshore migration of the precipitation zone via enhancement of convective activity. comparison of potential temperature and water vapor mixing ratio tendencies suggests that this cooling is substantially due to vertical advection by an ascent motion, which is possibly a component of shallow gravity waves. these results support the idea that gravity waves emanating from convective systems over land play a significant role in the offshore migration of the precipitation zone. | diurnal cycle of precipitation observed in the western coastal area of sumatra island: offshore preconditioning by gravity waves |
we investigate in detail the spectrum of gravitational waves induced by a peaked primordial curvature power spectrum generated in single-field inflationary models. we argue that the fnl parameter can be inferred by measuring the high frequency spectral tilt of the induced gravitational waves. we also show that the intrinsically non-gaussian impact of fnl in ωgw is to broaden its peak, although at a negligible level in order not to overproduce primordial black holes. we discuss possible degeneracies in the high frequency spectral tilt between fnl and a general equation of state of the universe w. finally, we discuss the constraints on the amplitude, peak and slope (or equivalently, fnl) of the primordial power spectrum by combining current and future gravitational wave experiments with limits on μ distortions from the cosmic microwave background. | probing non-gaussianities with the high frequency tail of induced gravitational waves |
it is now well-established that a dark, compact object, very likely a massive black hole (mbh) of around four million solar masses is lurking at the centre of the milky way. while a consensus is emerging about the origin and growth of supermassive black holes (with masses larger than a billion solar masses), mbhs with smaller masses, such as the one in our galactic centre, remain understudied and enigmatic. the key to understanding these holes—how some of them grow by orders of magnitude in mass—lies in understanding the dynamics of the stars in the galactic neighbourhood. stars interact with the central mbh primarily through their gradual inspiral due to the emission of gravitational radiation. also stars produce gases which will subsequently be accreted by the mbh through collisions and disruptions brought about by the strong central tidal field. such processes can contribute significantly to the mass of the mbh and progress in understanding them requires theoretical work in preparation for future gravitational radiation millihertz missions and x-ray observatories. in particular, a unique probe of these regions is the gravitational radiation that is emitted by some compact stars very close to the black holes and which could be surveyed by a millihertz gravitational-wave interferometer scrutinizing the range of masses fundamental to understanding the origin and growth of supermassive black holes. by extracting the information carried by the gravitational radiation, we can determine the mass and spin of the central mbh with unprecedented precision and we can determine how the holes "eat" stars that happen to be near them. | relativistic dynamics and extreme mass ratio inspirals |
space-based next-generation interferometers propose to measure the lyapunov exponents of the nearly bound geodesics that comprise the photon ring surrounding the black hole m87*. we argue that these classical lyapunov exponents equal the quantum ruelle resonances describing the late-time approach to thermal equilibrium of the quantum microstate holographically dual to any kerr black hole such as m87*. moreover, we identify 'near-ring regions' in the phase space of fields propagating on kerr that exhibit critical behavior, including emergent conformal symmetries. these are analogues for sub-extremal kerr of the much-studied 'near-horizon regions' of (near-)extremal black holes. the emergent conformal symmetries greatly constrain the observational predictions for the fine photon ring substructure around m87* and for quasinormal gravitational-wave ringdowns, as well as any proposal for a quantum holographic dual to the kerr black hole. more generally, we hope that our identification of several universal features of kerr spectroscopy provides a useful starting point for a bottom-up approach to holography for astrophysical black holes. | holography of the photon ring |
we investigate the strong gravitational lensing of spherically symmetric black holes in the novel einstein-gauss-bonnet (egb) gravity surrounded by unmagnetized plasma medium. the deflection angle in the strong deflection limit in egb spacetime with homogeneous plasma is derived. we find that both the coupling constant α in the novel egb gravity and the presence of plasma can affect the radius of photon sphere, strong field limit coefficient and other lensing observables significantly, while plasma has little effect on the angular image separation and the relative magnifications as α/m2 →-8 and α/m2 → 1, respectively. | strong gravitational lensing of a 4-dimensional einstein-gauss-bonnet black hole in homogeneous plasma |
measurements of black-hole spins from gravitational-wave observations of black-hole binaries with ground-based detectors are known to be hampered by partial degeneracies in the gravitational-wave phasing: between the two component spins, and between the spins and the binary's mass ratio, at least for signals that are dominated by the binary's inspiral. through the merger and ringdown, however, a different set of degeneracies apply. this suggests the possibility that, if the inspiral, merger and ringdown are all within the sensitive frequency band of a detector, we may be able to break these degeneracies and more accurately measure both spins. in this work we investigate our ability to measure individual spins for nonprecessing binaries, for a range of configurations and signal strengths, and conclude that in general the spin of the larger black hole will be measurable (at best) with observations from advanced ligo and virgo. this implies that in many applications waveform models parameterized by only one effective spin will be sufficient. our work does not consider precessing binaries or subdominant harmonics, although we provide some arguments why we expect that these will not qualitatively change our conclusions. | can we measure individual black-hole spins from gravitational-wave observations? |
the present work reports on a feasibility study commissioned by the chinese academy of sciences of china to explore various possible mission options to detect gravitational waves in space alternative to that of the elisa/lisa mission concept. based on the relative merits assigned to science and technological viability, a few representative mission options descoped from the alia mission are considered. a semi-analytic monte carlo simulation is carried out to understand the cosmic black hole merger histories and the possible scientific merits of the mission options in probing the light seed black holes and their coevolution with galaxies in early universe. the study indicates that, by choosing the armlength of the interferometer to be three million kilometers and shifting the sensitivity floor to around one-hundredth hz, together with a very moderate improvement on the position noise budget, there are certain mission options capable of exploring light seed, intermediate mass black hole binaries at high redshift that are not readily accessible to elisa/lisa, and yet the technological requirements seem to within reach in the next few decades for china. | descope of the alia mission |
current stellar evolution models predict a dearth of black holes (bhs) with masses $\gtrsim \! 50\, \rm m_\odot$ and $\lesssim \! 5\, \rm m_\odot$ , and intermediate-mass black holes (imbhs; $\sim \! 10^2\!-\! 10^5\rm\, m_\odot$ ) have not yet been detected beyond any reasonable doubt. a natural way to form massive bhs is through repeated mergers, detectable via gravitational wave emission with current ligo/virgo or future lisa and et observations. nuclear star clusters (nscs) have masses and densities high enough to retain most of the merger products, which acquire a recoil kick at the moment of merger. we explore the possibility that imbhs may be born as a result of repeated mergers in nscs, and show how their formation pathways depend on the nsc mass and density, and bh spin distribution. we find that bhs in the pair-instability mass gap can be formed and observed by ligo/virgo, and show that the typical mass of the ejected massive bhs is 400- $500\, \rm m_\odot$ , with velocities of up to a few thousand $\, \rm km\, s^{-1}$ . eventually, some of these imbhs can become the seeds of supermassive bhs, observed today in the centres of galaxies. in dwarf galaxies, they could potentially solve the abundance, core-cusp, too-big-to-fail, ultra-faint, and baryon-fraction issues via plausible feedback scenarios. | repeated mergers and ejection of black holes within nuclear star clusters |
in a very recent paper [1], we have proposed a novel 4-dimensional gravitational theory with two dynamical degrees of freedom, which serves as a consistent realization of d→4 einstein-gauss-bonnet gravity with the rescaled gauss-bonnet coupling constant ~α. this has been made possible by breaking a part of diffeomorphism invariance, and thus is consistent with the lovelock theorem. in the present paper, we study cosmological implications of the theory in the presence of a perfect fluid and clarify the similarities and differences between the results obtained from the consistent 4-dimensional theory and those from the previously considered, naive (and inconsistent) d→ 4 limit. studying the linear perturbations, we explicitly show that the theory only has tensorial gravitational degrees of freedom (besides the matter degree) and that for 0~α> and 0dot h<, perturbations are free of any pathologies so that we can implement the setup to construct early and/or late time cosmological models. interestingly, a k4 term appears in the dispersion relation of tensor modes which plays significant roles at small scales and makes the theory different than not only general relativity but also many other modified gravity theories as well as the naive (and inconsistent) d→ 4 limit. taking into account the k4 term, the observational constraint on the propagation of gravitational waves yields the bound ~α lesssim script o(1) ev-2. this is the first bound on the only parameter (besides the newton's constant and the choice of a constraint that stems from a temporal gauge fixing) in the consistent theory of d→ 4 einstein-gauss-bonnet gravity. | cosmology and gravitational waves in consistent d→ 4 einstein-gauss-bonnet gravity |
new theoretical approaches developed in the last years predict that macroscopic quantum gravity effects in black holes should lead to modifications of the gravitational wave signals expected in the framework of classical general relativity, with these modifications being characterized in certain scenarios by the existence of dampened rep-etitions of the primary signal. here we use the fact that non-perturbative corrections to the near-horizon external geometry of black holes are necessary for these modifications to exist, in order to classify different proposals and paradigms with respect to this criterion and study in a neat and systematic way their phenomenology. proposals that lead naturally to the existence of echoes in the late-time ringdown of gravitational wave signals from black hole mergers must share the replacement of black holes by horizonless configurations with a physical surface showing reflective properties in the relevant range of frequencies. on the other hand, proposals or paradigms that restrict quantum gravity effects on the external geometry to be perturbative, such as black hole complementarity or the closely related firewall proposal, do not display echoes. for the sake of completeness we exploit the interplay between the timescales associated with the formation of firewalls and the mechanism behind the existence of echoes in order to conclude that even unconventional distortions of the firewall concept (such as naked firewalls) do not lead to this phenomenon. | gravitational wave echoes from macroscopic quantum gravity effects |
inferring the properties of dense matter is one of the most exciting prospects from the measurement of gravitational waves from neutron star mergers. however, it requires reliable numerical simulations that incorporate viscous dissipation and energy transport as these can play a significant role in the survival time of the post-merger object. we calculate time scales for typical forms of dissipation and find that thermal transport and shear viscosity will not be important unless neutrino trapping occurs, which requires temperatures above 10 mev and gradients over length scales of 0.1 km or less. on the other hand, if direct-urca processes remain suppressed, leaving modified-urca processes to establish flavor equilibrium, then bulk viscous dissipation could provide significant damping to density oscillations right after merger. when comparing with data from state-of-the-art merger simulations, we find that the bulk viscosity takes values close to its resonant maximum in a typical merger, motivating a more careful assessment of the role of bulk viscous dissipation in the gravitational-wave signal from merging neutron stars. | viscous dissipation and heat conduction in binary neutron-star mergers |
gravitational-wave observations of black hole ringdowns are commonly used to characterize binary merger remnants and to test general relativity. these analyses assume linear black hole perturbation theory, in particular that the ringdown can be described in terms of quasinormal modes even for times approaching the merger. here we investigate a nonlinear effect during the ringdown, namely how a mode excited at early times can excite additional modes as it is absorbed by the black hole. this is a third-order secular effect: the change in the black hole mass causes a shift in the mode spectrum, so that the original mode is projected onto the new ones. using nonlinear simulations, we study the ringdown of a spherically symmetric scalar field around an asymptotically anti-de sitter black hole, and we find that this "absorption-induced mode excitation" is the dominant nonlinear effect. we show that this effect takes place well within the nonadiabatic regime, so we can analytically estimate it using a sudden mass-change approximation. adapting our estimation technique to asymptotically flat schwarzschild black holes, we expect absorption-induced mode excitation to play a role in the analysis and interpretation of current and future gravitational wave observations. | nonlinear effects in the black hole ringdown: absorption-induced mode excitation |
utilizing gravitational-wave (gw) lensing opens a new way to understand the small-scale structure of the universe. we show that, in spite of its coarse angular resolution and short duration of observation, ligo can detect the gw lensing induced by small structures, in particular by compact dark matter (dm) or the primordial black hole of 10 - 105 m⊙ , which remains an interesting dm candidate. the lensing is detected through gw frequency chirping, creating the natural and rapid change of lensing patterns: frequency-dependent amplification and modulation of gw waveforms. as a highest-frequency gw detector, ligo is a unique gw lab to probe such light compact dm. with the design sensitivity of advanced ligo, one-year observation by three detectors can optimistically constrain the compact dm density fraction fdm to the level of a few percent. | gravitational-wave fringes at ligo: detecting compact dark matter by gravitational lensing |
in the context of neutron star mergers, we study the gravitational wave spectrum of the merger remnant using numerical relativity simulations. postmerger spectra are characterized by a main peak frequency f2 related to the particular structure and dynamics of the remnant hot hypermassive neutron star. we show that f2 is correlated with the tidal coupling constant κ2t that characterizes the binary tidal interactions during the late-inspiral merger. the relation f2(κ2t) depends very weakly on the binary total mass, mass ratio, equation of state, and thermal effects. this observation opens up the possibility of developing a model of the gravitational spectrum of every merger unifying the late-inspiral and postmerger descriptions. | modeling the complete gravitational wave spectrum of neutron star mergers |
we propose a gravitational-wave detection method based on heterodyne laser links and light-pulse atom interferometry that enables high sensitivity gravitational-wave detection in the 0.1-mhz to 1-hz frequency band using a single, long (>108 m), detector baseline. the detection baseline in previous atom-based proposals was constrained by the need for a reference laser to remain collimated over the optical propagation path between two satellites. here we circumvent this requirement by employing a strong local oscillator laser near each atom ensemble that is phase referenced or phase locked to the reference laser beam. longer baselines offer a number of potential advantages, including enhanced sensitivity, simplified atom optics, and reduced atomic source flux requirements. | atom-interferometric gravitational-wave detection using heterodyne laser links |
we use gauge/gravity duality to write down an effective low energy holographic theory of charge density waves. we consider a simple gravity model which breaks translations spontaneously in the dual field theory in a homogeneous manner, capturing the low energy dynamics of phonons coupled to conserved currents. we first focus on the leading two-derivative action, which leads to excited states with nonzero strain. we show that including subleading quartic derivative terms leads to dynamical instabilities of ads2 translation invariant states and to stable phases breaking translations spontaneously. we compute analytically the real part of the electric conductivity. the model allows to construct lifshitz-like hyperscaling violating quantum critical ground states breaking translations spontaneously. at these critical points, the real part of the dc conductivity can be metallic or insulating. | effective holographic theory of charge density waves |
we point out that dark matter which is produced non-adiabatically in a phase transition (pt) with fast bubble walls receives a boost in velocity which leads to long free-streaming lengths. we find that this could be observed via the suppressed matter power spectrum for dark matter masses around \mathbf{ 10^8 - 10^9}108-109 gev and energy scales of the pt around \mathbf{ 10^{2} - 10^3}102-103 gev. the pt should take place at the border of the supercooled regime, i.e. approximately when the universe becomes vacuum dominated. this work offers novel physics goals for galaxy surveys, lyman-\alphaɑ, stellar stream, lensing, and 21-cm observations, and connects these to the gravitational waves from such phase transitions, and more speculatively to possible telescope signals of heavy dark matter decay. | hot and heavy dark matter from a weak scale phase transition |
we study stochastic gravitational waves from cosmic strings generated in an ultraviolet-complete model for pseudo-nambu-goldstone dark matter with a hidden ${u(1)}$ gauge symmetry. the dark matter candidate in this model can naturally evade direct detection bounds and easily satisfy other phenomenological constraints. the bound on the dark matter lifetime implies an ultraviolet scale higher than $ 10^9\; \mathrm{gev} $ . the spontaneous ${u(1)}$ symmetry breaking at such a high scale would induce cosmic strings with high tension, resulting in a stochastic gravitational wave background with a high energy density. we investigate the constraints from current gravitational wave experiments as well as the future sensitivity. we find that most viable parameter points can be well studied in future gravitational wave experiments. *supported by the national natural science foundation of china (11805288) | gravitational waves from cosmic strings associated with pseudo-nambu-goldstone dark matter |
rotations of axion fields in the early universe can produce dark matter and the matter-antimatter asymmetry of the universe. we point out that the rotation can generate an observable amount of a stochastic gravitational wave (gw) background. it can be doubly enhanced in a class of models in which the equation of state of the rotations rapidly changes from a nonrelativistic matterlike one to a kinationlike one by (1) the so-called poltergeist mechanism and (2) slower redshift of gws compared to the axion-kination fluid. in supersymmetric uv completion, future gw observations can probe the supersymmetry-breaking scale up to 107 gev even if the axion does not directly couple to the standard model fields. | gravitational wave production from axion rotations right after a transition to kination |
we consider gravitational wave production by bubble collisions during a cosmological first-order phase transition. in the literature, such spectra have been estimated by simulating the bubble dynamics, under so-called thin-wall and envelope approximations in a flat background metric. however, we show that, within these assumptions, the gravitational wave spectrum can be estimated in an analytic way. our estimation is based on the observation that the two-point correlator of the energy-momentum tensor ⟨t (x )t (y )⟩ can be expressed analytically under these assumptions. though the final expressions for the spectrum contain a few integrations that cannot be calculated explicitly, we can easily estimate it numerically. as a result, it is found that the most of the contributions to the spectrum come from single-bubble contribution to the correlator, and in addition the fall-off of the spectrum at high frequencies is found to be proportional to f-1 . we also provide fitting formulas for the spectrum. | gravitational waves from bubble collisions: an analytic derivation |
we assess the contribution of dynamical hardening by direct three-body scattering interactions to the rate of stellar-mass black hole binary (bhb) mergers in galactic nuclei. we derive an analytic model for the single-binary encounter rate in a nucleus with spherical and disc components hosting a super-massive black hole (smbh). we determine the total number of encounters ngw needed to harden a bhb to the point that inspiral due to gravitational wave emission occurs before the next three-body scattering event. this is done independently for both the spherical and disc components. using a monte carlo approach, we refine our calculations for ngw to include gravitational wave emission between scattering events. for astrophysically plausible models, we find that typically ngw ≲ 10. we find two separate regimes for the efficient dynamical hardening of bhbs: (1) spherical star clusters with high central densities, low-velocity dispersions, and no significant keplerian component and (2) migration traps in discs around smbhs lacking any significant spherical stellar component in the vicinity of the migration trap, which is expected due to effective orbital inclination reduction of any spherical population by the disc. we also find a weak correlation between the ratio of the second-order velocity moment to velocity dispersion in galactic nuclei and the rate of bhb mergers, where this ratio is a proxy for the ratio between the rotation- and dispersion-supported components. because discs enforce planar interactions that are efficient in hardening bhbs, particularly in migration traps, they have high merger rates that can contribute significantly to the rate of bhb mergers detected by the advanced laser interferometer gravitational-wave observatory. | on the rate of black hole binary mergers in galactic nuclei due to dynamical hardening |
as potential candidates of dark matter, primordial black holes (pbhs) are within the core scopes of various astronomical observations. in light of the explosive development of gravitational wave (gw) and radio astronomy, we thoroughly analyze a stochastic background of cosmological gws, induced by overly large primordial density perturbations, with several spikes that was inspired by the sound speed resonance effect and can predict a particular pattern on the mass spectrum of pbhs. with a specific mechanism for pbh formation, we for the first time perform the study of such induced gws that originate from both the inflationary era and the radiation-dominated phase. we report that, besides the traditional process of generating gws during the radiation-dominated phase, the contribution of the induced gws in the sub-hubble regime during inflation can become significant at the critical frequency band because of a narrow resonance effect. all contributions sum together to yield a specific profile of the energy spectrum of gws that can be of observable interest in forthcoming astronomical experiments. our study sheds light on the possible joint probe of pbhs via various observational windows of multimessenger astronomy, including the search for electromagnetic effects with astronomical telescopes and the stochastic background of relic gws with gw instruments. | when primordial black holes from sound speed resonance meet a stochastic background of gravitational waves |
soliton gases represent large random soliton ensembles in physical systems that exhibit integrable dynamics at the leading order. despite significant theoretical developments and observational evidence of ubiquity of soliton gases in fluids and optical media, their controlled experimental realization has been missing. we report a controlled synthesis of a dense soliton gas in deep-water surface gravity waves using the tools of nonlinear spectral theory [inverse scattering transform (ist)] for the one-dimensional focusing nonlinear schrödinger equation. the soliton gas is experimentally generated in a one-dimensional water tank where we demonstrate that we can control and measure the density of states, i.e., the probability density function parametrizing the soliton gas in the ist spectral phase space. nonlinear spectral analysis of the generated hydrodynamic soliton gas reveals that the density of states slowly changes under the influence of perturbative higher-order effects that break the integrability of the wave dynamics. | nonlinear spectral synthesis of soliton gas in deep-water surface gravity waves |
coupling of the earth's surface with the atmosphere is achieved through an exchange of momentum, energy, and mass in the atmospheric boundary layer. in mountainous terrain, this exchange results from a combination of multiple transport processes, which act and interact on different spatial and temporal scales, including, for example, orographic gravity waves, thermally driven circulations, moist convection, and turbulent motions. incorporating these exchange processes and previous studies, a new definition of the atmospheric boundary layer in mountainous terrain, a mountain boundary layer (mbl), is defined. this paper summarizes some of the major current challenges in measuring, understanding, and eventually parameterizing the relevant transport processes and the overall exchange between the mbl and the free atmosphere. further details on many aspects of the exchange in the mbl are discussed in several other papers in this issue. | current challenges in understanding and predicting transport and exchange in the atmosphere over mountainous terrain |
within the framework of self-force theory, we compute the gravitational-wave energy flux through second order in the mass ratio for compact binaries in quasicircular orbits. our results are consistent with post-newtonian calculations in the weak field, and they agree remarkably well with numerical-relativity simulations of comparable-mass binaries in the strong field. we also find good agreement for binaries with a spinning secondary or a slowly spinning primary. our results are key for accurately modeling extreme-mass-ratio inspirals and will be useful in modeling intermediate-mass-ratio systems. | gravitational-wave energy flux for compact binaries through second order in the mass ratio |
we investigate the enhancement of the curvature perturbations in a single-field slow-roll inflation with a spectator scalar field kinetically coupled to the inflaton. the coupling term with a periodic function of inflaton triggers the exponential growth of the spectator field perturbations, which indirectly amplifies the curvature perturbations to produce a sizable abundance of primordial black holes (pbhs). this scenario is found to be insensitive to the inflationary background. we study two distinct populations of the stochastic gravitational wave background (sgwb) produced in this scenario, i.e., induced by the scalar perturbations during the inflationary era and the radiation-dominated era, respectively. with the appropriate choices of parameter space, we consider two pbh mass windows of great interest. one is pbhs of masses o (10-12)m⊙ that can be a vital component of dark matter, and the predicted total energy spectrum of sgwb shows a unique profile and is detectable by lisa and taiji. the other is pbhs of masses o (10 )m⊙ which can provide consistent explanation for the ligo-virgo events. more interestingly, the predicted gravitational wave signal from the radiation-dominated era may account for the nanograv 12.5-yr results. | primordial black holes and stochastic gravitational wave background from inflation with a noncanonical spectator field |
we compare the spectrum of the stochastic gravitational wave background produced in several models of cosmic strings with the common-spectrum process recently reported by nanograv. we discuss theoretical uncertainties in computing such a background, and show that despite such uncertainties, cosmic strings remain a good explanation for the potential signal, but the consequences for cosmic string parameters depend on the model. superstrings could also explain the signal, but only in a restricted parameter space where their network behavior is effectively identical to that of ordinary cosmic strings. | comparison of cosmic string and superstring models to nanograv 12.5-year results |
we study the possible occurrence of the hadron-quark phase transition (pt) during the merging of neutron star binaries by hydrodynamical simulations employing a set of temperature-dependent hybrid equations of state (eoss). following previous work, we describe an unambiguous and measurable signature of deconfined quark matter in the gravitational-wave (gw) signal of neutron star binary mergers including equal-mass and unequal-mass systems of different total binary mass. the softening of the eos by the pt at higher densities, i.e., after merging, leads to a characteristic increase of the dominant postmerger gw frequency fpeak relative to the tidal deformability λ inferred during the premerger inspiral phase. hence, measuring such an increase of the postmerger frequency provides evidence for the presence of a strong pt. if the postmerger frequency and the tidal deformability are compatible with results from purely baryonic eos models yielding very tight relations between fpeak and λ , a strong pt can be excluded up to a certain density. we find tight correlations of fpeak and λ with the maximum density during the early postmerger remnant evolution. these gw observables thus inform about the density regime which is probed by the remnant and its gw emission. exploiting such relations, we devise a directly applicable, concrete procedure to constrain the onset density of the qcd pt from future gw measurements. we point out two interesting scenarios: if no indications for a pt are inferred from a gw detection, our procedure yields a lower limit on the onset density of the hadron-quark pt. on the contrary, if a merger event reveals evidence for the occurrence of deconfined quark matter, the inferred gw parameters set an upper limit on the pt onset density. both scenarios would thus have strong implications for high-density matter physics, e.g., determining the range of validity of nuclear physics and constraining the properties for quark deconfinement. these prospects demonstrate the importance of simultaneously measuring pre- and postmerger gw signals to exploit the complementarity of the information encoded in both phases. hence, our work stresses the value added by dedicated high-frequency gw instruments. | constraining the onset density of the hadron-quark phase transition with gravitational-wave observations |
context. massive stars are predicted to excite internal gravity waves (igws) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. these igws are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationally.aims: we aim to characterise the photometric detection of igws across a large number of o and early-b stars in the hertzsprung-russell diagram, and explain the ubiquitous detection of stochastic variability in the photospheres of massive stars.methods: we combined high-precision time-series photometry from the nasa transiting exoplanet survey satellite with high-resolution ground-based spectroscopy of 70 stars with spectral types o and b to probe the relationship between the photometric signatures of igws and parameters such as spectroscopic mass, luminosity, and macroturbulence.results: a relationship is found between the location of a star in the spectroscopic hertzsprung-russell diagram and the amplitudes and frequencies of stochastic photometric variability in the light curves of massive stars. furthermore, the properties of the stochastic variability are statistically correlated with macroturbulent velocity broadening in the spectral lines of massive stars.conclusions: the common ensemble morphology for the stochastic low-frequency variability detected in space photometry and its relationship to macroturbulence is strong evidence for igws in massive stars, since these types of waves are unique in providing the dominant tangential velocity field required to explain the observed spectroscopy. | photometric detection of internal gravity waves in upper main-sequence stars. ii. combined tess photometry and high-resolution spectroscopy |
any new vector boson with non-zero mass (a 'dark photon' or 'proca boson') that is present during inflation is automatically produced at this time from vacuum fluctuations and can comprise all or a substantial fraction of the observed dark matter density, as shown by graham, mardon, and rajendran. we demonstrate, utilising both analytic and numerical studies, that such a scenario implies an extremely rich dark matter substructure arising purely from the interplay of gravitational interactions and quantum effects. due to a remarkable parametric coincidence between the size of the primordial density perturbations and the scale at which quantum pressure is relevant, a substantial fraction of the dark matter inevitably collapses into gravitationally bound solitons, which are fully quantum coherent objects. the central densities of these 'dark photon star', or 'proca star', solitons are typically a factor 106 larger than the local background dark matter density, and they have characteristic masses of 10-16 m ⊙ (10-5 ev/m)3/2, where m is the mass of the vector. during and post soliton production a comparable fraction of the energy density is initially stored in, and subsequently radiated from, long-lived quasi-normal modes. furthermore, the solitons are surrounded by characteristic 'fuzzy' dark matter halos in which quantum wave-like properties are also enhanced relative to the usual virialized dark matter expectations. lower density compact halos, with masses a factor of ~ 105 greater than the solitons, form at much larger scales. we argue that, at minimum, the solitons are likely to survive to the present day without being tidally disrupted. this rich substructure, which we anticipate also arises from other dark photon dark matter production mechanisms, opens up a wide range of new direct and indirect detection possibilities, as we discuss in a companion paper. | dark photon stars: formation and role as dark matter substructure |
controlling interfaces of phase-separating fluid mixtures is key to the creation of diverse functional soft materials. traditionally, this is accomplished with surface-modifying chemical agents. using experiment and theory, we studied how mechanical activity shapes soft interfaces that separate an active and a passive fluid. chaotic flows in the active fluid give rise to giant interfacial fluctuations and noninertial propagating active waves. at high activities, stresses disrupt interface continuity and drive droplet generation, producing an emulsion-like active state composed of finite-sized droplets. when in contact with a solid boundary, active interfaces exhibit nonequilibrium wetting transitions, in which the fluid climbs the wall against gravity. these results demonstrate the promise of mechanically driven interfaces for creating a new class of soft active matter. | dynamics of active liquid interfaces |
we consider a mechanism for producing a significant population of primordial black holes (pbhs) and an observable stochastic gravitational wave background (sgwb) within string theory inspired models of inflation. in this framework where inflaton is identified as a non-compact axion-like field, sub-leading non-perturbative effects can superimpose steep cliffs connected by smooth plateaus onto the underlying axion potential. in the presence of coupling to abelian gauge fields, the motion of axion on the cliff-like region(s) of its potential triggers a localized production of one helicity state of gauge fields due to the temporary fast-roll of axion around such a feature. in this setup, primordial fluctuations sourced by vector fields exhibit a localized peak in momentum space corresponding to modes that exit the horizon when the axion velocity is maximal. as an application of this general mechanism, we present an example of axion inflation which both matches planck observations at cmb scales and generates a population of light pbhs (mpbh simeq 10-13 msolar) that can account for all dark matter. in this scenario, the enhanced scalar fluctuations that leads to pbhs also generate an observable sgwb of induced origin at lisa scales. the amplitude and shape of the resulting gw signal inherits specific properties (such as non-gaussianity and its shape) of its scalar sources that may allow us to distinguish this mechanism from other inflationary scenarios and astrophysical backgrounds. this gw signal together with an observation of pbh distribution at the corresponding scales can thus provide a window to the inflationary dynamics on scales much smaller than those probed by cosmic microwave background (cmb) and large scale structure (lss) measurements. | primordial black holes as dark matter and gravitational waves from bumpy axion inflation |
the current observational constraints still leave a substantial mass window ∼ [10-16 ,10-14 ] ∪ [10-13 ,10-12 ]m⊙ for primordial black holes (pbhs) representing all of dark matter (dm) in our universe. the gravitational waves (gws) induced by the curvature perturbations are inevitably generated during the formation of these pbhs, and fall in the frequency band of lisa. such scalar induced gravitational waves (sigws) are supposed to be definitely detected by lisa even when the second-order local-type non-gaussianity characterized by the parameter fnl is taken into account. in this letter, we give a comprehensive analysis of the gws induced by the local-type non-gaussian curvature perturbations up to the third-order denoted by the non-linear parameter gnl, and we find that a log-dependent slope of sigws in the infrared region is generically predicted and the amplitude of sigws can be further suppressed by several orders of magnitude. as a result, the null-detection of sigws by lisa cannot rule out the possibility of pbhs making up all of dm. | gravitational waves induced by the local-type non-gaussian curvature perturbations |
the recent multimessenger observation of the short gamma-ray burst (sgrb) grb 170817a together with the gravitational wave (gw) event gw170817 provides evidence for the long-standing hypothesis associating sgrbs with binary neutron star (bns) mergers. the nature of the remnant object powering the sgrb, which could have been either an accreting black hole (bh) or a long-lived magnetized neutron star (ns), is, however, still uncertain. general relativistic magnetohydrodynamic (grmhd) simulations of the merger process represent a powerful tool to unravel the jet launching mechanism, but so far most simulations focused the attention on a bh as the central engine, while the long-lived ns scenario remains poorly investigated. here, we explore the latter by performing a grmhd bns merger simulation extending up to ∼100 ms after merger, much longer than any previous simulation of this kind. this allows us to (i) study the emerging structure and amplification of the magnetic field and observe a clear saturation at magnetic energy emag∼1051 erg , (ii) follow the magnetically supported expansion of the outer layers of the remnant ns and its evolution into an ellipsoidal shape without any surrounding torus, and (iii) monitor density, magnetization, and velocity along the axis, observing no signs of jet formation. we also argue that the conditions at the end of the simulation disfavor later jet formation on subsecond timescales if no bh is formed. furthermore, we examine the rotation profile of the remnant, the conversion of rotational energy associated with differential rotation, the overall energy budget of the system, and the evolution of the gw frequency spectrum. finally, we perform an additional simulation where we induce the collapse to a bh ∼70 ms after merger, in order to gain insights on the prospects for massive accretion tori in case of a late collapse. we find that a mass around ∼0.1 m⊙ remains outside the horizon, which has the potential to power a sgrb via the blandford-znajek mechanism when accreted. | first 100 ms of a long-lived magnetized neutron star formed in a binary neutron star merger |
in this work we shall study einstein gauss-bonnet theories and we investigate when these can have their gravitational wave speed equal to the speed of light, which is unity in natural units, thus becoming compatible with the striking event gw170817. we demonstrate how this is possible and we show that if the scalar coupling to the gauss-bonnet invariant is constrained to satisfy a differential equation, the gravitational wave speed becomes equal to one. accordingly, we investigate the inflationary phenomenology of the resulting restricted einstein gauss-bonnet model, by assuming that the slow-roll conditions hold true. as we demonstrate, the compatibility with the observational data coming from the planck 2018 collaboration, can be achieved, even for a power-law potential. we restricted ourselves to the study of the power-law potential, due to the lack of analyticity, however more realistic potentials can be used, in this case though the calculations are not easy to be performed analytically. we also pointed out that a string-corrected extension of the einstein gauss-bonnet model we studied, containing terms of the form ∼ ξ (ϕ)gab∂a ϕ∂b ϕ can also provide a theory with gravity waves speed ct2 = 1 in natural units, if the function ξ (ϕ) is appropriately constrained, however in the absence of the gauss-bonnet term ∼ ξ (ϕ) g the gravity waves speed can never be ct2 = 1. finally, we discuss which extensions of the above models can provide interesting cosmologies, since any combination of f (r , x , ϕ) gravities with the above string-corrected einstein gauss-bonnet models can yield ct2 = 1, with x = 1/2 ∂μ ϕ∂μ ϕ. | inflationary phenomenology of einstein gauss-bonnet gravity compatible with gw170817 |
we consider the thermal effects into the evaluation of the dark matter production process. with the assistance of the right handed neutrinos, the freeze-in massive particle dark matter production history can be modified by the two-step phase transitions. the kinematic of decay/inverse decay or annihilation processes can be affected by the finite temperature effects as the universe cools down. the history of the symmetry respected by the model can be revealed by the dm relic abundance evolution processes. the strong first order electroweak phase transition generated gravitational waves can be probed. the number of extra scalars for the hierarchy problem can be probed through the higgs off-shell searches at the lhc. | thermally modified sterile neutrino portal dark matter and gravitational waves from phase transition: the freeze-in case |
we study gravitational-wave production from bubble dynamics (bubble collisions and sound waves) during a cosmic first-order phase transition with an analytic approach. we first propose modeling the system with the thin-wall approximation but without the envelope approximation often adopted in the literature, in order to take bubble propagation after collisions into account. the bubble walls in our setup are considered as modeling the scalar field configuration and/or the bulk motion of the fluid. we next write down analytic expressions for the gravitational-wave spectrum, and evaluate them with numerical methods. it is found that, in the long-lasting limit of the collided bubble walls, the spectrum grows from propto f3 to propto f1 in low frequencies, showing a significant enhancement compared to the one with the envelope approximation. it is also found that the spectrum saturates in the same limit, indicating a decrease in the correlation of the energy-momentum tensor at late times. we also discuss the implications of our results to gravitational-wave production both from bubble collisions (scalar dynamics) and sound waves (fluid dynamics). | gravitational waves from bubble dynamics: beyond the envelope |
we investigate the inflationary cosmology involving an s u (5 ) gut (grand unified theory) singlet scalar with nonminimal coupling to the ricci scalar. in this scenario the scale of grand unification is set by the inflaton vacuum expectation value when the inflaton rolls down its potential towards its minimum v , thereby relating inflationary dynamics to gut symmetry breaking with a prediction of r ≃0.025 for the tensor-to-scalar ratio to be tested by the next generation of cmb experiments. we show in this inflationary framework involving an inflection point how a suitable choice of parameters in s u (5 ) leads to a bump in the scalar power spectrum with the production of primordial blackholes (pbh) of masses 1017- 1018 g (10-16- 10-15m⊙). we derive the constraints on the self-quartic and mixed-quartic couplings of the inflaton in s u (5 ) that are consistent with the inflationary analysis. moreover, we also show that this scenario leads to large amplitude induced second-order tensor perturbations propagating as gravitational waves (gws) with an amplitude ωgwh2∼5 ×10-10- 10-8 and peak frequency fpeak∼(0.1 - 300 ) hz , which can be detected in the next-generation gw observatories like lisa, bbo, et, etc. thus, we unify the s u (5 ) framework with pbh via inflection-point inflation showing how the upcoming measurements of pbh and gw will enable us to probe the scale of s u (5 ) symmetry breaking, and thereby complementing the laboratory-based experiments. we also discuss scenarios involving the pati-salam and trinification gauge groups and its impact on quartic and mixed-quartic couplings that may lead to pbh and detectable gw signals. | cosmological probes of grand unification: primordial black holes and scalar-induced gravitational waves |
the recent discoveries of high-energy cosmic neutrinos and gravitational waves from astrophysical objects have led to a new era of multimessenger astrophysics. in particular, electromagnetic follow-up observations triggered by these cosmic signals have proved to be highly successful and have brought about new opportunities in time-domain astronomy. we review high-energy particle production in various classes of astrophysical transient phenomena related to black holes and neutron stars, and discuss how high-energy emission can be used to reveal the underlying physics of neutrino and gravitational-wave sources. | high-energy multimessenger transient astrophysics |
alternative theories of gravity predict modifications in the propagation of gravitational waves (gw) through space-time. one of the smoking-gun predictions of such theories is the change in the gw luminosity distance to gw sources as a function of redshift relative to the electromagnetic (em) luminosity distance expected from em probes. we propose a multimessenger test of the theory of general relativity from the propagation of gws by combining em and gw observations to resolve these issues from gw sources without em counterparts (which are also referred to as dark standard sirens). by using the relation between the geometric distances accessible from baryon acoustic oscillation measurements, and luminosity distance measurements from the gw sources, we can measure any deviation from the general theory of relativity via the gw sources of unknown redshift that will be detectable by networks of gw detectors such as ligo, virgo, and kagra. using this technique, the fiducial value of the frictional term can be measured to a precision $\xi _0=0.98^{+0.04}_{-0.23}$ after marginalizing over redshift dependence, cosmological parameters, and gw bias parameters with ~3500 dark standard sirens of masses $30\, \rm m_\odot$ each distributed up to redshift z = 0.5. for a fixed redshift dependence, a value of $\xi _0=0.99^{+0.02}_{-0.02}$ can be measured with a similar number of dark sirens. application of our methodology to the far more numerous dark standard sirens detectable with next-generation gw detectors, such as lisa, einstein telescope and cosmic explorer, will allow achievement of higher accuracy than possible from use of bright standard sirens. | testing the general theory of relativity using gravitational wave propagation from dark standard sirens |
the densest state of matter in the universe is uniquely realized inside the central cores of the neutron star. while first-principles evaluation of the equation of state of such matter remains as one of the long-standing problems in nuclear theory, evaluation in light of neutron star phenomenology is feasible. here we show results from a novel theoretical technique to utilize a deep neural network with supervised learning. we input up-to-date observational data from neutron star x-ray radiations into the trained neural network and estimate a relation between the pressure and the mass density. our results are consistent with extrapolation from the conventional nuclear models and the experimental bound on the tidal deformability inferred from gravitational wave observation. | mapping neutron star data to the equation of state using the deep neural network |
we revisit the effects of an early matter-dominated era on gravitational waves induced by scalar perturbations. we carefully take into account the evolution of the gravitational potential, the source of these induced gravitational waves, during a gradual transition from an early matter-dominated era to the radiation-dominated era, where the transition timescale is comparable to the hubble time at that time. realizations of such a gradual transition include the standard perturbative reheating with a constant decay rate. contrary to previous works, we find that the presence of an early matter-dominated era does not necessarily enhance the induced gravitational waves due to the decay of the gravitational potential around the transition from an early matter-dominated era to the radiation-dominated era. | gravitational waves induced by scalar perturbations during a gradual transition from an early matter era to the radiation era |
we show the peak magnitude for orphan afterglows from the jets of gravitational wave (gw) detected black hole/neutron star - neutron star (bh/ns-ns) mergers highly depend on the jet half-opening angle θj. short γ-ray bursts (grbs) with a homogeneous jet structure and θj > 10°, the orphan afterglow viewed at the typical inclination for a gw detected event, 38°, are brighter at optical frequencies than the comparable macronova emission. structured jets, where the energetics and lorentz factor γ vary with angle from the central axis, may have low-γ components where the prompt emission is suppressed; gw electromagnetic (em) counterparts may reveal a population of failed-grb orphan afterglows. using a monte carlo method assuming an ns-ns detection limit we show the fraction of gw-em counterparts from homogeneous, two-component, power-law structured and gaussian jets where the variable structure models include a wide low energy and γ component: for homogeneous jets, with a θj = 6° and typical short grb parameters, we find r-band magnitude mr ≤ 21 counterparts for ∼13.6 per cent of gw detected mergers; where jet structure extends to a half-opening angle of 25°, two-component jets produce mr ≤ 21 counterparts in ∼30 per cent of gw detected mergers, power-law structured-jets result in ∼37 per cent and gaussian jets with our parameters ∼13 per cent. we show the features in the light curves from orphan afterglows can be used to indicate the presence of extended structure. | electromagnetic counterparts to structured jets from gravitational wave detected mergers |
as-yet undiscovered light bosons may constitute all or part of the dark matter (dm) of our universe, and are expected to have (weak) self-interactions. we show that the quartic self-interactions generically induce the capture of dark matter from the surrounding halo by external gravitational potentials such as those of stars, including the sun. this leads to the subsequent formation of dark matter bound states supported by such external potentials, resembling gravitational atoms (e.g. a solar halo around our own sun). their growth is governed by the ratio ξ foc ≡ λdb/r ⋆ between the de broglie wavelength of the incoming dm waves, λdb, and the radius of the ground state r ⋆. for ξ foc ≲ 1, the gravitational atom grows to an (underdense) steady state that balances the capture of particles and the inverse (stripping) process. for ξ foc ≳ 1, a significant gravitational-focusing effect leads to exponential accumulation of mass from the galactic dm halo into the gravitational atom. for instance, a dark matter axion with mass of the order of 10-14 ev and decay constant between 107 and 108 gev would form a dense halo around the sun on a timescale comparable to the lifetime of the solar system, leading to a local dm density at the position of the earth 𝒪(104) times larger than that expected in the standard halo model. for attractive self-interactions, after its formation, the gravitational atom is destabilized at a large density, which leads to its collapse; this is likely to be accompanied by emission of relativistic bosons (a `bosenova'). | a generic formation mechanism of ultralight dark matter solar halos |
we present a new python package, gwbench, implementing the well-established fisher information formalism as a fast and straightforward tool for the purpose of gravitational-wave benchmarking, i.e. the estimation of signal-to-noise ratios and measurement errors of gravitational waves observed by a network of detectors. such an infrastructure is necessary due to the high computational cost of bayesian parameter estimation methods which renders them less effective for the scientific assessment of gravitational waveforms, detectors, and networks of detectors, especially when determining their effects on large populations of gravitational-wave sources spread throughout the universe. gwbench further gives quick access to detector locations and sensitivities, while including the effects of earth's rotation on the latter, as well as waveform models and their derivatives, while giving access to the host of waveforms available in the lsc algorithm library. with the provided functionality, gwbench is relevant for a wide variety of applications in gravitational-wave astronomy such as waveform modeling, detector development, cosmology, and tests of general relativity. | gwbench: a novel fisher information package for gravitational-wave benchmarking |
computationally efficient waveforms are of central importance for gravitational wave data analysis of inspiraling and coalescing compact binaries. we show that the postadiabatic (pa) approximation to the effective one-body (eob) description of the binary dynamics, when pushed to high order, allows one to accurately and efficiently compute the waveform of coalescing binary neutron stars (bnss) or black holes (bbhs) up to a few orbits before merger. this is accomplished bypassing the usual need of numerically solving the relative eob dynamics described by a set of ordinary differential equations (odes). under the assumption that radiation reaction is small, hamilton's equations for the momenta can be solved analytically for given values of the relative separation. time and orbital phase are then recovered by simple numerical quadratures. for the least adiabatic bbh case, equal-mass, quasiextremal spins antialigned with the orbital angular momentum, 6pa/8pa orders are able to generate waveforms that accumulate less than 10-3 rad of phase difference with respect to the complete eob ones up to ∼3 orbits before merger. analogous results hold for bnss. the pa waveform generation is extremely efficient: for a standard bns system from 10 hz, a nonoptimized matlab implementation of the teobresums eob model in the pa approximation is almost 100 times faster (∼0.09 s ) than the corresponding c ++ code based on a standard ode solver. once optimized further, our approach will allow us to (i) avoid the use of the fast, but often inaccurate, post-newtonian inspiral waveforms, drastically reducing the impact of systematics due to inspiral waveform modeling, and (ii) alleviate the need of constructing eob waveform surrogates to be used in parameter estimation codes. | efficient effective one body time-domain gravitational waveforms |
we show that fragmentation of the inflaton into long-lived spatially localized oscillon configurations can lead to copious production of black holes. in simple inflation models primordial black holes of sublunar mass can form, and they can account for all of the dark matter. we also explore the possibility that solar-mass primordial black holes, particularly relevant for gravitational wave astronomy, are produced from the same mechanism. | primordial black holes from inflaton fragmentation into oscillons |
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