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Register a new userA detailed analysis of GW190521 with phenomenological waveform models
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H\\'ector Estell\\'es
Publication date
2021
fields
Physics
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English
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In this paper we present an extensive analysis of the GW190521 gravitational wave event with the current (fourth) generation of phenomenological waveform models for binary black hole coalescences. GW190521 stands out from other events since only a few wave cycles are observable. This leads to a number of challenges, one being that such short signals are prone to not resolve approximate waveform degeneracies, which may result in multi-modal posterior distributions. The family of waveform models we use includes a new fast time-domain model IMRPhenomTPHM, which allows us extensive tests of different priors and robustness with respect to variations in the waveform model, including the content of spherical harmonic modes. We clarify some issues raised in a recent paper [Nitz&Capano], associated with possible support for a high-mass ratio source, but confirm their finding of a multi-modal posterior distribution, albeit with important differences in the statistical significance of the peaks. In particular, we find that the support for both masses being outside the PISN mass-gap, and the support for an intermediate mass ratio binary are drastically reduced with respect to what Nitz&Capano found. We also provide updated probabilities for associating GW190521 to the potential electromagnetic counterpart from ZTF.
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This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) on September 14, 2015 [1]. Reference presented parameter estimation [2] of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom) and a 11-dimensional nonprecessing effective-one-body (EOB) model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR). Here we present new results that include a 15-dimensional precessing-spin waveform model (precessing EOBNR) developed within the EOB formalism. We find good agreement with the parameters estimated previously [2], and we quote updated component masses of $35^{+5}_{-3}mathrm{M}_odot$ and $30^{+3}_{-4}mathrm{M}_odot$ (where errors correspond to 90% symmetric credible intervals). We also present slightly tighter constraints on the dimensionless spin magnitudes of the two black holes, with a primary spin estimate $0.65$ and a secondary spin estimate $0.75$ at 90% probability. Reference [2] estimated the systematic parameter-extraction errors due to waveform-model uncertainty by combining the posterior probability densities of precessing IMRPhenom and nonprecessing EOBNR. Here we find that the two precessing-spin models are in closer agreement, suggesting that these systematic errors are smaller than previously quoted.
On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of $85^{+21}_{-14} M_{odot}$ and $66^{+17}_{-18} M_{odot}$ (90 % credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, and has only a 0.32 % probability of being below $65 M_{odot}$. We calculate the mass of the remnant to be $142^{+28}_{-16} M_{odot}$, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is $5.3^{+2.4}_{-2.6}$ Gpc, corresponding to a redshift of $0.82^{+0.28}_{-0.34}$. The inferred rate of mergers similar to GW190521 is $0.13^{+0.30}_{-0.11},mathrm{Gpc}^{-3},mathrm{yr}^{-1}$.
The recent observation of GW190412, the first high-mass ratio binary black-hole (BBH) merger, by the LIGO-Virgo Collaboration (LVC) provides a unique opportunity to probe the impact of subdominant harmonics and precession effects encoded in a gravitational wave signal. We present refined estimates of source parameters for GW190412 using texttt{NRSur7dq4}, a recently developed numerical relativity waveform surrogate model that includes all $ell leq 4$ spin-weighted spherical harmonic modes as well as the full physical effects of precession. We compare our results with two different variants of phenomenological precessing BBH waveform models, texttt{IMRPhenomPv3HM} and texttt{IMRPhenomXPHM}, as well as to the LVC results. Our results are broadly in agreement with texttt{IMRPhenomXPHM} results and the reported LVC analysis compiled with the texttt{SEOBNRv4PHM} waveform model, but in tension with texttt{IMRPhenomPv3HM}. Using the texttt{NRSur7dq4} model, we provide a tighter constraint on the mass-ratio ($0.26^{+0.08}_{-0.06}$) as compared to the LVC estimate of $0.28^{+0.13}_{-0.07}$ (both reported as median values withs 90% credible intervals). We also constrain the binary to be more face-on, and find a broader posterior for the spin precession parameter. We further find that even though $ell=4$ harmonic modes have negligible signal-to-noise ratio, omission of these modes will influence the estimated posterior distribution of several source parameters including chirp mass, effective inspiral spin, luminosity distance, and inclination. We also find that commonly used model approximations, such as neglecting the asymmetric modes (which are generically excited during precession), have negligible impact on parameter recovery for moderate SNR-events similar to GW190412.
The combined observation of gravitational and electromagnetic waves from the coalescence of two neutron stars marks the beginning of multi-messenger astronomy with gravitational waves (GWs). The development of accurate gravitational waveform models is a crucial prerequisite to extract information about the properties of the binary system that generated a detected GW signal. In binary neutron star systems (BNS), tidal effects also need to be incorporated in the modeling for an accurate waveform representation. Building on previous work [Phys.Rev.D96 121501], we explore the performance of inspiral-merger waveform models that are obtained by adding a numerical relativity (NR) based approximant for the tidal part of the phasing (NRTidal) to existing models for nonprecessing and precessing binary black hole systems (SEOBNRv4, PhenomD and PhenomPv2), as implemented in the LSC Algorithm Library Suite. The resulting BNS waveforms are compared and contrasted to target waveforms hybridizing NR waveforms, covering the last approx. 10 orbits up to merger and extending through the postmerger phase, with inspiral waveforms calculated from 30Hz obtained with TEOBResumS. The latter is a state-of-the-art effective-one-body waveform model that blends together tidal and spin effects. We probe that the combination of the PN-based self-spin terms and of the NRTidal description is necessary to obtain minimal mismatches (< 0.01) and phase differences (< 1 rad) with respect to the target waveforms. However, we also discuss possible improvements and drawbacks of the NRTidal approximant in its current form, since we find that it tends to overestimate the tidal interaction with respect to the TEOBResumS model during the inspiral.
We reanalyze gravitational waves from binary-neutron-star mergers GW170817 and GW190425 using a numerical-relativity (NR) calibrated waveform model, the TF2+_Kyoto model, which includes nonlinear tidal terms. For GW170817, by imposing a uniform prior on the binary tidal deformability $tilde{Lambda}$, the symmetric $90%$ credible interval of $tilde{Lambda}$ is estimated to be $481^{+436}_{-359}$ and $402^{+465}_{-279}$ for the case of $f_mathrm{max}=1000$ and $2048~mathrm{Hz}$, respectively, where $f_mathrm{max}$ is the maximum frequency in the analysis. We also reanalyze the event with other waveform models: two post-Newtonian waveform models (TF2_PNTidal and TF2+_PNTidal), the TF2+_NRTidal model that is another NR calibrated waveform model, and its upgrade, the TF2+_NRTidalv2 model. While estimates of parameters other than $tilde{Lambda}$ are broadly consistent among various waveform models, our results indicate that estimates of $tilde{Lambda}$ depend on waveform models. However, the difference is smaller than the statistical error. For GW190425, we can only obtain little information on the binary tidal deformability. The systematic difference among the NR calibrated waveform models will become significant to measure $tilde{Lambda}$ as the number of detectors and events increase and sensitivities of detectors are improved.
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