Laura Cadonati

Transient noise artifacts (called``glitches'') frequently occur in ground-based gravitational-wave detectors, sometimes in close temporal coincidence to real GW events. As more events are detected, mitigation of these glitches becomes increasingly important. Previously, the BayesWave algorithm has shown success in removing glitches from data used for binary coalescence parameter estimation. As we observe more of the gravitational-wave universe, we may discover signals from novel sources lacking robust models. In such cases, confidently distinguishing generic transients from glitches will be crucial. This work investigates BayesWave's ability to recover simulated ad-hoc gravitational-wave signals overlapping instrumental glitches. We will present results on the match between recovered and simulated waveforms, and how well the algorithm correctly identifies data containing both signals and glitches.

Binary black hole (BBH) Hyperbolic Encounters involve two black holes in a fly-by orbit, with emission of gravitational-wave (GW) bremsstrahlung. BBH hyperbolic encounters may be prevalent in dense stellar clusters, where collision rates are high. These encounters can be modeled by a small number of parameters: the relative velocity, total mass, and the impact parameter, a geometric property of the orbit. The corresponding GW signal would manifest in ground-based interferometers as a single-cycle transient. We present a study to constrain detection rates for current and next generation ground-based GW detectors. We use waveforms from numerical simulations which cover a discrete grid of mass ratios ranging from q= 1 (equal mass) to asymmetric mass ratio q= 16. We use BayesWave, a model-agnostic algorithm which characterizes features in the data regardless of an a priori assumed model. For this …

The detection of GW170817 (Abbott et al. 2017b) coincident with the short gamma-ray burst GRB 170817A (Goldstein et al. 2017; Savchenko et al. 2017) was a groundbreaking discovery for the multimessenger era. Not only was it the first binary neutron star (BNS) merger detected by the gravitational-wave (GW) instruments Advanced LIGO (Aasi et al. 2015) and Advanced Virgo (Acernese et al. 2014), it was also the first, and to date only, GW detection with a confirmed electromagnetic (EM) counterpart. Since then, the search for EM emission from more of these extreme events has been at the forefront of multimessenger astronomy, particularly in the gamma-ray energy band, since GRB 170817A demonstrated that BNS mergers are a progenitor of short gamma-ray bursts (GRBs; Abbott et al. 2017a). GWs have also been observed from the mergers of other compact objects, such as binary black hole (BBH) and …

LIGO and Virgo have reported~ 90 compact binary coalescences in their first three Observing Runs. The ongoing fourth Observing Run will add even more events. A discrepancy between reconstructed gravitational-wave waveforms from template-based analyses (using GR approximants) and unmodeled analyses (that use minimal assumptions on signal source) could indicate deviations from GR, incomplete models (missing higher order modes/precession), or noise artifacts. Previous work calculated the match between the unmodeled BayesWave waveform and those from template-based parameter estimation to evaluate the waveform consistency for individual events. With more detections, we are interested in possible deviations across event ensembles. Low signal-to-noise ratio events are often not included as unmodeled methods do not reconstruct them well. We will present an injection study to show whether …

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U (1) B− L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U (1) B− L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

We present a streamlined, externally triggered gravitational wave (GW) search for multi-messenger compact binary coalescence (CBC) events. Large or sub-threshold EM catalogs are good candidates for multi-messenger searches with LIGO-Virgo-KAGRA gravitational wave data but, depending on the telescope, can come with hundreds or thousands of events per year to follow up. PyGRB is the state-of-the-art modeled CBC multi-messenger search algorithm in LVK data. It is sensitive to quieter GW signals than the all-sky search for CBC events. However, it is computationally expensive, making it unsuited for large multi-messenger follow up efforts. We introduce a hierarchical search to process these large catalogs. This hierarchical approach uses time of arrival and sky location of an external trigger to identify potential signals in LVK data. Potential events are then passed to the more computationally costly deep …

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM.

H17. 00003: Visualizing the black hole postmerger gravitational wave emission profile and horizon geometry

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

The frequency evolution of gravitational wave signals from the merger of compact binaries follows a slow build-up during the inspiral that peaks at merger, forming the characteristic" chirp" pattern in the signal's time-frequency map. Herein we introduce a framework for localizing further characteristic structures in the time-frequency space of gravitational wave signals using the continuous wavelet transform. We consider two example cases containing specific patterns in the postmerger stage of the signal that are rich with information on the source's physical nature: highly-inclined black hole binaries with asymmetric mass ratio, and neutron star binaries with postmerger remnant oscillations. It is demonstrated that the choice of quality factor Q plays a central role in distinguishing the postmerger features from that of the inspiral, with black hole systems preferring lower Q and neutron star systems preferring higher Q. To …

Despite the growing number of candidates and the insight they have provided, the astrophysical sites and processes that produce the observed merging binaries remain uncertain. Multiple viable scenarios exist. The binary black holes could have formed in an isolated stellar binary (eg, Bethe & Brown 1998; Dominik et al. 2015; Inayoshi et al. 2017; Marchant et al. 2016; de Mink & Mandel 2016; Gallegos-Garcia et al. 2021), via dynamical interactions in dense stellar clusters (eg, Portegies Zwart & McMillan 2000; Banerjee et al. 2010; Ziosi et al. 2014; Morscher et al. 2015; Mapelli 2016; Rodriguez et al. 2016a; Askar et al. 2017) or triple systems (eg, Antonini et al. 2017; Martinez et al. 2020; Vigna-Gómez et al. 2021), or via gas capture in the disks of active galactic nuclei (AGN; eg, McKernan et al. 2012; Bartos et al. 2017; Fragione et al. 2019; Tagawa et al. 2020).

The third Gravitational-Wave Transient Catalog (GWTC-3) describes signals detected with Advanced LIGO and Advanced Virgo up to the end of their third observing run. Updating the previous GWTC-2.1, we present candidate gravitational waves from compact binary coalescences during the second half of the third observing run (O3b) between 1 November 2019, 15∶ 00 Coordinated Universal Time (UTC) and 27 March 2020, 17∶ 00 UTC. There are 35 compact binary coalescence candidates identified by at least one of our search algorithms with a probability of astrophysical origin p astro> 0.5. Of these, 18 were previously reported as low-latency public alerts, and 17 are reported here for the first time. Based upon estimates for the component masses, our O3b candidates with p astro> 0.5 are consistent with gravitational-wave signals from binary black holes or neutron-star–black-hole binaries, and we identify …

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in April of 2019 and lasting six months, O3b starting in November of 2019 and lasting five months, and O3GK starting in April of 2020 and lasting 2 weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.

We investigate the impact of transient noise artifacts, or {\it glitches}, on gravitational wave inference, and the efficacy of data cleaning procedures in recovering unbiased source properties. Due to their time-frequency morphology, broadband glitches demonstrate moderate to significant biasing of posterior distributions away from true values. In contrast, narrowband glitches have negligible biasing effects owing to distinct signal and glitch morphologies. We inject simulated binary black hole signals into data containing three common glitch types from past LIGO-Virgo observing runs, and reconstruct both signal and glitch waveforms using {\tt BayesWave}, a wavelet-based Bayesian analysis. We apply the standard LIGO-Virgo-KAGRA deglitching procedure to the detector data - we subtract the glitch waveform estimated by the joint {\tt BayesWave} inference before performing parameter estimation with detailed compact binary waveform models. We find that this deglitching effectively mitigates bias from broadband glitches, with posterior peaks aligning with true values post deglitching. This provides a baseline validation of existing techniques, while demonstrating waveform reconstruction improvements to the Bayesian algorithm for robust astrophysical characterization in glitch-prone detector data.

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass ) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities at Gpc yr at 90\% confidence level.

The gravitational waves produced by binary black hole systems with an asymmetric mass ratio have been shown to exhibit a characteristic double-chirp pattern when viewed from a highly inclined orientation. These chirp patterns are composed of mixed higher-order modes produced during the ringdown, due to regions of high curvature on the distorted apparent horizon. Herein we motivate a means to reduce the double-chirp phenomenon into a single-number parameter that describes its strength relative to that of the overall signal. This is accomplished by adapting a continuous wavelet transform scan to utilize a chirplet (a Sine-Guassian wavelet with a forward chirp rate) as the mother wavelet, enhancing the contrast of the spectrogram. The development of this technique is discussed, along with prospects towards mapping the apparent horizon evolution.

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The discovery of a gravitational wave (GW) signal from a binary neutron star (BNS) merger (Abbott et al. 2017a) and the kilonova emission from its remnant (Coulter et al. 2017; Abbott et al. 2017b) provided the first GW standard siren measurement of the cosmic expansion history (Abbott et al. 2017c). As pointed out by Schutz (1986), the GW signal from a compact binary coalescence directly measures the luminosity distance to the source without any additional distance calibrator, earning these sources the name “standard sirens”(Holz & Hughes 2005). Measuring the cosmic expansion as a function of the cosmological redshift is one of the key avenues with which to explore the constituents of the universe, along with the other canonical probes such as the cosmic microwave background (CMB; Spergel et al. 2003, 2007; Komatsu et al. 2011; Ade et al. 2014, 2016; Aghanim et al. 2020), baryon acoustic oscillations …

We introduce a streamlined, externally triggered gravitational wave (GW) search for multi-messenger compact binary coalescence events. Telescopes with large or sub-threshold catalogs are good candidates for multi-messenger searches with LIGO-Virgo-KAGRA GW data but can come with thousands of events per year to follow up. PyGRB, the state-of-the-art CBC multi-messenger search algorithm, is sensitive but computationally expensive, processing only~ 100 events per year at 2 or more weeks of wall time each. This makes it unsuited for large multi-messenger follow up efforts. We introduce a hierarchical search algorithm, PyNu, to process these large catalogs to pass potential coincident events to PyGRB for follow-up. Our algorithm is based in PyCBC, a Python-based GW search package used by the LVK to identify events in GWTC-3. In our hierarchical approach, we use a trigger's time of arrival and sky …

Fast radio bursts (FRBs) are millisecond duration radio pulses that have been observed out to cosmological distances, several with inferred redshifts greater than unity (Lorimer et al. 2007; Cordes & Chatterjee 2019; Petroff et al. 2019). Although intensely studied for more than a decade, the emission mechanisms and progenitor populations of FRBs are still one of the outstanding questions in astronomy. Some FRBs have been shown to repeat (Amiri et al. 2019a; CHIME/FRB Collaboration et al. 2019; Kumar et al. 2019), and the recent association of an FRB with the Galactic magnetar SGR 1935+ 2154 proves that magnetars can produce FRBs (Bochenek et al. 2020; CHIME/FRB Collaboration et al. 2020). Alternative progenitors and mechanisms to produce nonrepeating FRBs are still credible and have so far not been ruled out (Zhang 2020a). Data currently suggest that both repeating and nonrepeating classes of …