Journal articles: 'Third observing run'

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Soni, S., C. Austin, A. Effler, R. M. S. Schofield, G. González, V. V. Frolov, J. C. Driggers, et al. "Reducing scattered light in LIGO’s third observing run." Classical and Quantum Gravity 38, no. 2 (January 22, 2021): 025016. http://dx.doi.org/10.1088/1361-6382/abc906.

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Dal Canton, Tito, Alexander H. Nitz, Bhooshan Gadre, Gareth S. Cabourn Davies, Verónica Villa-Ortega, Thomas Dent, Ian Harry, and Liting Xiao. "Real-time Search for Compact Binary Mergers in Advanced LIGO and Virgo's Third Observing Run Using PyCBC Live." Astrophysical Journal 923, no. 2 (December 1, 2021): 254. http://dx.doi.org/10.3847/1538-4357/ac2f9a.

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Abstract The third observing run of Advanced LIGO and Advanced Virgo took place between 2019 April and 2020 March and resulted in dozens of gravitational-wave candidates, many of which are now published as confident detections. A crucial requirement of the third observing run was the rapid identification and public reporting of compact binary mergers, which enabled massive follow-up observation campaigns with electromagnetic and neutrino observatories. PyCBC Live is a low-latency search for compact binary mergers based on frequency-domain matched filtering, which was used during the second and third observing runs, together with other low-latency analyses, to generate these rapid alerts from the data acquired by LIGO and Virgo. This paper describes and evaluates the improvements made to PyCBC Live after the second observing run, which defined its operation and performance during the third observing run.

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Herner, Kenneth, James Annis, Alyssa Garcia, Marcelle Soares-Santos, Dillon Brout, Noemi Glaeser, Nora Sherman, et al. "The updated DESGW processing pipeline for the third LIGO/VIRGO observing run." EPJ Web of Conferences 245 (2020): 01008. http://dx.doi.org/10.1051/epjconf/202024501008.

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The DESGW group seeks to identify electromagnetic counterparts of gravitational wave events seen by the LIGO-VIRGO network, such as those expected from binary neutron star mergers or neutron star-black hole mergers. DESGW was active throughout the first two LIGO observing seasons, following up several binary black hole mergers and the first binary neutron star merger, GW170817. This work describes the modifications to the observing strategy generation and image processing pipeline between the second (ending in August 2017) and third (beginning in April 2019) LIGO observing seasons. The modifications include a more robust observing strategy generator, further parallelization of the image reduction software and difference imaging processing pipeline, data transfer streamlining, and a web page listing identified counterpart candidates that updates in real time. Taken together, the additional parallelization steps enable the identification of potential electromagnetic counterparts within fully calibrated search images in less than one hour, compared to the 3-5 hours it would typically take during the first two seasons. These performance improvements are critical to the entire EM follow-up community, as rapid identification (or rejection) of candidates enables detailed and rapid spectroscopic follow-up by multiple instruments, leading to more information about the environment immediately following such gravitational wave events.

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Fiori, Irene, Federico Paoletti, Maria Concetta Tringali, Kamiel Janssens, Christos Karathanasis, Alexis Menéndez-Vázquez, Alba Romero-Rodríguez, et al. "The Hunt for Environmental Noise in Virgo during the Third Observing Run." Galaxies 8, no. 4 (December 7, 2020): 82. http://dx.doi.org/10.3390/galaxies8040082.

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The first twenty years of operation of gravitational-wave interferometers have shown that these detectors are affected by physical disturbances from the surrounding environment. These are seismic, acoustic, or electromagnetic disturbances that are mainly produced by the experiment infrastructure itself. Ambient noise can limit the interferometer sensitivity or potentially generate transients of non-astrophysical origin. Between 1 April 2019 and 27 March 2020, the network of second generation interferometers—LIGO, Virgo and GEO—performed the third joined observing run, named O3, searching for gravitational signals from the deep universe. A thorough investigation has been done on each detector before and during data taking in order to optimize its sensitivity and duty cycle. In this paper, we first revisit typical sources of environmental noise and their coupling paths, and we then describe investigation methods and tools. Finally, we illustrate applications of these methods in the hunt for environmental noise at the Virgo interferometer during the O3 run and its preparation phase. In particular, we highlight investigation techniques that might be useful for the next observing runs and the future generation of terrestrial interferometers.

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Abbott, R., H. Abe, F. Acernese, K. Ackley, S. Adhicary, N. Adhikari, R. X. Adhikari, et al. "Open Data from the Third Observing Run of LIGO, Virgo, KAGRA, and GEO." Astrophysical Journal Supplement Series 267, no. 2 (July 28, 2023): 29. http://dx.doi.org/10.3847/1538-4365/acdc9f.

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Abstract 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 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two 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 data set, 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.

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Andres, N., M. Assiduo, F. Aubin, R. Chierici, D. Estevez, F. Faedi, G. M. Guidi, et al. "Assessing the compact-binary merger candidates reported by the MBTA pipeline in the LIGO–Virgo O3 run: probability of astrophysical origin, classification, and associated uncertainties." Classical and Quantum Gravity 39, no. 5 (February 3, 2022): 055002. http://dx.doi.org/10.1088/1361-6382/ac482a.

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Abstract We describe the method used by the multi-band template analysis (MBTA) pipeline to compute the probability of astrophysical origin, p astro, of compact binary coalescence candidates in LIGO–Virgo data from the third observing run (O3). The calculation is performed as part of the offline analysis and is used to characterize candidate events, along with their source classification. The technical details and the implementation are described, as well as the results from the first half of the third observing run (O3a) published in GWTC-2.1. The performance of the method is assessed on injections of simulated gravitational-wave signals in O3a data using a parameterization of p astro as a function of the MBTA combined ranking statistic. Possible sources of statistical and systematic uncertainties are discussed, and their effect on p astro quantified.

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Abbasi, R., M. Ackermann, J. Adams, N. Aggarwal, J. A. Aguilar, M. Ahlers, M. Ahrens, et al. "IceCube Search for Neutrinos Coincident with Gravitational Wave Events from LIGO/Virgo Run O3." Astrophysical Journal 944, no. 1 (February 1, 2023): 80. http://dx.doi.org/10.3847/1538-4357/aca5fc.

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Abstract Using data from the IceCube Neutrino Observatory, we searched for high-energy neutrino emission from the gravitational-wave events detected by the advanced LIGO and Virgo detectors during their third observing run. We did a low-latency follow-up on the public candidate events released during the detectors’ third observing run and an archival search on the 80 confident events reported in the GWTC-2.1 and GWTC-3 catalogs. An extended search was also conducted for neutrino emission on longer timescales from neutron star containing mergers. Follow-up searches on the candidate optical counterpart of GW190521 were also conducted. We used two methods; an unbinned maximum likelihood analysis and a Bayesian analysis using astrophysical priors, both of which were previously used to search for high-energy neutrino emission from gravitational-wave events. No significant neutrino emission was observed by any analysis, and upper limits were placed on the time-integrated neutrino flux as well as the total isotropic equivalent energy emitted in high-energy neutrinos.

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Page, K. L., P. A. Evans, A. Tohuvavohu, J. A. Kennea, N. J. Klingler, S. B. Cenko, S. R. Oates, et al. "Swift-XRT follow-up of gravitational wave triggers during the third aLIGO/Virgo observing run." Monthly Notices of the Royal Astronomical Society 499, no. 3 (October 1, 2020): 3459–80. http://dx.doi.org/10.1093/mnras/staa3032.

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ABSTRACT The Neil Gehrels Swift Observatory followed up 18 gravitational wave (GW) triggers from the LIGO/Virgo collaboration during the O3 observing run in 2019/2020, performing approximately 6500 pointings in total. Of these events, four were finally classified (if real) as binary black hole (BH) triggers, six as binary neutron star (NS) events, two each of NSBH and Mass Gap triggers, one an unmodelled (Burst) trigger, and the remaining three were subsequently retracted. Thus far, four of these O3 triggers have been formally confirmed as real gravitational wave events. While no likely electromagnetic counterparts to any of these GW events have been identified in the X-ray data (to an average upper limit of 3.60 × 10−12 erg cm−2 s−1 over 0.3–10 keV), or at other wavelengths, we present a summary of all the Swift-XRT observations performed during O3, together with typical upper limits for each trigger observed. The majority of X-ray sources detected during O3 were previously uncatalogued; while some of these will be new (transient) sources, others are simply too faint to have been detected by earlier survey missions such as ROSAT. The all-sky survey currently being performed by eROSITA will be a very useful comparison for future observing runs, reducing the number of apparent candidate X-ray counterparts by up to 95 per cent.

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Aubin, F., F. Brighenti, R. Chierici, D. Estevez, G. Greco, G. M. Guidi, V. Juste, et al. "The MBTA pipeline for detecting compact binary coalescences in the third LIGO–Virgo observing run." Classical and Quantum Gravity 38, no. 9 (April 8, 2021): 095004. http://dx.doi.org/10.1088/1361-6382/abe913.

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D’Onofrio, Luca. "The targeted search for gravitational waves from known pulsars." Journal of Physics: Conference Series 2429, no. 1 (February 1, 2023): 012038. http://dx.doi.org/10.1088/1742-6596/2429/1/012038.

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Abstract In this paper, I review the latest results by the LIGO-Virgo-Kagra Collaboration for the targeted search of continuous gravitational waves (CWs) from 236 pulsars. First, I present an overview of the types of the CW search. Then, I show the results obtained using data from the third observing run of LIGO and Virgo detectors combined with data from the second observing run. No evidence of gravitational waves has been found but it is possible to set upper limits on the CW amplitude and on the pulsar ellipticity at 95% confidence level. 23 of the analyzed pulsars have strain amplitudes that are lower than the limits calculated from their electromagnetically measured spin-down rates.

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Zhao, Zhi-Chao, Zhoujian Cao, and Sai Wang. "Search for the Birefringence of Gravitational Waves with the Third Observing Run of Advanced LIGO-Virgo." Astrophysical Journal 930, no. 2 (May 1, 2022): 139. http://dx.doi.org/10.3847/1538-4357/ac62d3.

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Abstract Gravitational waves would attain birefringence during their propagation from distant sources to the Earth, when the charge, parity, and time reversal (CPT) symmetry is broken. If it was sizeable enough, such birefringence could be measured by the Advanced LIGO, Virgo, and KAGRA detector network. In this work, we place constraints on the birefringence of gravitational waves with the third observing run of this network, i.e., two catalogs GWTC-2 and GWTC-3. For the dispersion relation ω 2 = k 2 ± 2ζ k 3, our analysis shows the up-to-date strictest limit on the CPT-violating parameter, i.e., ζ = 4.07 − 5.79 + 5.91 × 10 − 17 m , at 68% confidence level. This limit is stricter by ∼5 times when compared to the existing one (∼2× 10−16 m) and stands for the first ∼10 GeV-scale test of the CPT symmetry in gravitational waves. The results of the Bayes factor strongly disfavor the birefringence scenario of gravitational waves.

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Modafferi, Luana M., Joan Moragues, and David Keitel. "Search for long-duration transient gravitational waves from glitching pulsars during LIGO—Virgo third observing run." Journal of Physics: Conference Series 2156, no. 1 (December 1, 2021): 012079. http://dx.doi.org/10.1088/1742-6596/2156/1/012079.

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Abstract Pulsars are spinning neutron stars which emit an electromagnetic beam. We expect pulsars to slowly decrease their rotational frequency. However, sudden increases of the rotational frequency have been observed from different pulsars. These events are called “glitches” and they are followed by a relaxation phase with timescales from days to months. Gravitational wave (GW) emission may follow these peculiar events. We give an overview of an analysis of GW data from the Advanced LIGO and Virgo third observing run (O3) searching for transient GW signals lasting hours to months after glitches in known pulsars. The search method consists of placing a template grid in frequency–spindown space with fixed grid spacings. Then, for each point we compute the transient F-statistic which is maximized over a set of transient parameters like the duration and start time of the potential signals. A threshold on the detection statistic is then set, and we search for peaks over the parameter space for each candidate.

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Antier, S., S. Agayeva, V. Aivazyan, S. Alishov, E. Arbouch, A. Baransky, K. Barynova, et al. "The first six months of the Advanced LIGO’s and Advanced Virgo’s third observing run with GRANDMA." Monthly Notices of the Royal Astronomical Society 492, no. 3 (November 11, 2019): 3904–27. http://dx.doi.org/10.1093/mnras/stz3142.

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ABSTRACT We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient events to enhance their follow-up and reduce the delay between the initial detection and optical confirmation. The GRANDMA programme mainly focuses on follow-up of gravitational-wave alerts to find and characterize the electromagnetic counterpart during the third observational campaign of the Advanced LIGO and Advanced Virgo detectors. But it allows for follow-up of any transient alerts involving neutrinos or gamma-ray bursts, even those with poor spatial localization. We present the different facilities, tools, and methods we developed for this network and show its efficiency using observations of LIGO/Virgo S190425z, a binary neutron star merger candidate. We furthermore report on all GRANDMA follow-up observations performed during the first six months of the LIGO–Virgo observational campaign, and we derive constraints on the kilonova properties assuming that the events’ locations were imaged by our telescopes.

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Aiello, S., A. Albert, S. Alves Garre, Z. Aly, A. Ambrosone, F. Ameli, M. Andre, et al. "Searches for neutrino counterparts of gravitational waves from the LIGO/Virgo third observing run with KM3NeT." Journal of Cosmology and Astroparticle Physics 2024, no. 04 (April 1, 2024): 026. http://dx.doi.org/10.1088/1475-7516/2024/04/026.

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Abstract The KM3NeT neutrino telescope is currently being deployed at two different sites in the Mediterranean Sea. First searches for astrophysical neutrinos have been performed using data taken with the partial detector configuration already in operation. The paper presents the results of two independent searches for neutrinos from compact binary mergers detected during the third observing run of the LIGO and Virgo gravitational wave interferometers. The first search looks for a global increase in the detector counting rates that could be associated with inverse beta decay events generated by MeV-scale electron anti-neutrinos. The second one focuses on upgoing track-like events mainly induced by muon (anti-)neutrinos in the GeV–TeV energy range. Both searches yield no significant excess for the sources in the gravitational wave catalogs. For each source, upper limits on the neutrino flux and on the total energy emitted in neutrinos in the respective energy ranges have been set. Stacking analyses of binary black hole mergers and neutron star-black hole mergers have also been performed to constrain the characteristic neutrino emission from these categories.

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Rastinejad, J. C., K. Paterson, W. Fong, D. J. Sand, M. J. Lundquist, G. Hosseinzadeh, E. Christensen, et al. "A Systematic Exploration of Kilonova Candidates from Neutron Star Mergers during the Third Gravitational-wave Observing Run." Astrophysical Journal 927, no. 1 (March 1, 2022): 50. http://dx.doi.org/10.3847/1538-4357/ac4d34.

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Abstract We present a comprehensive analysis of 653 optical candidate counterparts reported during the third gravitational-wave (GW) observing run. Our sample concentrates on candidates from the 15 events (published in GWTC-2, GWTC-3, or not retracted on GraceDB) that had a >1% chance of including a neutron star in order to assess their viability as true kilonovae. In particular, we leverage tools available in real time, including pre-merger detections and cross-matching with catalogs (i.e., point-source, variable-star, quasar and host-galaxy redshift data sets), to eliminate 65% of candidates in our sample. We further employ spectroscopic classifications, late-time detections, and light-curve behavior analyses and conclude that 66 candidates remain viable kilonovae. These candidates lack sufficient information to determine their classifications, and the majority would require luminosities greater than that of AT 2017gfo. Pre-merger detections in public photometric survey data and comparison of cataloged host-galaxy redshifts with the GW event distances are critical to incorporate into vetting procedures, as these tools eliminated >20% and >30% of candidates, respectively. We expect that such tools that leverage archival information will significantly reduce the strain on spectroscopic and photometric follow-up resources in future observing runs. Finally, we discuss the critical role prompt updates from GW astronomers to the EM community play in reducing the number of candidates requiring vetting.

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Parazin, B., Michael W. Coughlin, Leo P. Singer, Vaidehi Gupta, and Shreya Anand. "Foraging with MUSHROOMS: A Mixed-integer Linear Programming Scheduler for Multimessenger Target of Opportunity Searches with the Zwicky Transient Facility." Astrophysical Journal 935, no. 2 (August 1, 2022): 87. http://dx.doi.org/10.3847/1538-4357/ac7fa2.

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Abstract Electromagnetic follow-up of gravitational-wave detections is very resource intensive, taking up hours of limited observation time on dozens of telescopes. Creating more efficient schedules for follow-up will lead to a commensurate increase in counterpart location efficiency without using more telescope time. Widely used in operations research and telescope scheduling, mixed-integer linear programming is a strong candidate to produce these higher-efficiency schedules, as it can make use of powerful commercial solvers that find globally optimal solutions to provided problems. We detail a new target-of-opportunity scheduling algorithm designed with Zwicky Transient Facility in mind that uses mixed-integer linear programming. We compare its performance to gwemopt, the tuned heuristic scheduler used by the Zwicky Transient Facility and other facilities during the third LIGO–Virgo gravitational-wave observing run. This new algorithm uses variable-length observing blocks to enforce cadence requirements and to ensure field observability, along with having a secondary optimization step to minimize slew time. We show that by employing a hybrid method utilizing both this scheduler and gwemopt, the previous scheduler used, in concert, we can achieve an average improvement in detection efficiency of 3%–11% over gwemopt alone for a simulated binary neutron star merger data set consistent with LIGO–Virgo’s third observing run, highlighting the potential of mixed-integer target of opportunity schedulers for future multimessenger follow-up surveys.

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Kiendrebeogo, R. Weizmann, Amanda M. Farah, Emily M. Foley, Abigail Gray, Nina Kunert, Anna Puecher, Andrew Toivonen, et al. "Updated Observing Scenarios and Multimessenger Implications for the International Gravitational-wave Networks O4 and O5." Astrophysical Journal 958, no. 2 (November 21, 2023): 158. http://dx.doi.org/10.3847/1538-4357/acfcb1.

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Abstract An advanced LIGO and Virgo’s third observing run brought another binary neutron star merger (BNS) and the first neutron-star black hole mergers. While no confirmed kilonovae were identified in conjunction with any of these events, continued improvements of analyses surrounding GW170817 allow us to project constraints on the Hubble Constant (H 0), the Galactic enrichment from r-process nucleosynthesis, and ultra-dense matter possible from forthcoming events. Here, we describe the expected constraints based on the latest expected event rates from the international gravitational-wave network and analyses of GW170817. We show the expected detection rate of gravitational waves and their counterparts, as well as how sensitive potential constraints are to the observed numbers of counterparts. We intend this analysis as support for the community when creating scientifically driven electromagnetic follow-up proposals. During the next observing run O4, we predict an annual detection rate of electromagnetic counterparts from BNS of 0.43 − 0.26 + 0.58 ( 1.97 − 1.2 + 2.68 ) for the Zwicky Transient Facility (Rubin Observatory).

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Abbott, R., T. D. Abbott, F. Acernese, K. Ackley, C. Adams, N. Adhikari, R. X. Adhikari, et al. "Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO–Virgo Run O3b." Astrophysical Journal 928, no. 2 (April 1, 2022): 186. http://dx.doi.org/10.3847/1538-4357/ac532b.

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Abstract We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC–2020 March 27 17:00 UTC). We conduct two independent searches: a generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate.

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de Jaeger, T., B. J. Shappee, C. S. Kochanek, K. Z. Stanek, J. F. Beacom, T. W.-S. Holoien, Todd A. Thompson, A. Franckowiak, and S. Holmbo. "ASAS-SN search for optical counterparts of gravitational-wave events from the third observing run of Advanced LIGO/Virgo." Monthly Notices of the Royal Astronomical Society 509, no. 3 (November 1, 2021): 3427–40. http://dx.doi.org/10.1093/mnras/stab3141.

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ABSTRACT We report on the search for electromagnetic counterparts to the nine gravitational-wave events with a >60 per cent probability of containing a neutron star during the third observing run (O3) of the Laser Interferometer Gravitational-Wave Observatory (LIGO)–Virgo Collaboration (LVC) with the All-Sky Automated Survey for SuperNovae (ASAS-SN). No optical counterparts associated with a gravitational-wave event were found. However, thanks to its network of telescopes, the average area visible to at least one ASAS-SN site during the first 10 h after the trigger contained ∼30 per cent of the integrated source location probability. Through a combination of normal operations and target-of-opportunity observations, ASAS-SN observations of the highest probability fields began within 1 h of the trigger for four of the events. After 24 h, ASAS-SN observed >60 per cent of total probability for three events and >40 per cent for all but one of the events. This is the largest area coverage to a depth of g = 18.5 mag from any survey with published coverage statistics for seven of the nine events. With its observing strategy, five sites around the world, and a large field of view, ASAS-SN will be one of the leading surveys to optically search for nearby neutron star mergers during LVC fourth observation run (O4).

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Abbott, R., T. D. Abbott, F. Acernese, K. Ackley, C. Adams, N. Adhikari, R. X. Adhikari, et al. "Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo." Astronomy & Astrophysics 659 (March 2022): A84. http://dx.doi.org/10.1051/0004-6361/202141452.

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Intermediate-mass black holes (IMBHs) span the approximate mass range 100−105 M⊙, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼150 M⊙ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200 M⊙ and effective aligned spin 0.8 at 0.056 Gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc−3 yr−1.

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Bode, Nina, Joseph Briggs, Xu Chen, Maik Frede, Peter Fritschel, Michael Fyffe, Eric Gustafson, et al. "Advanced LIGO Laser Systems for O3 and Future Observation Runs." Galaxies 8, no. 4 (December 8, 2020): 84. http://dx.doi.org/10.3390/galaxies8040084.

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The advanced LIGO gravitational wave detectors need high power laser sources with excellent beam quality and low-noise behavior. We present a pre-stabilized laser system with 70 W of output power that was used in the third observing run of the advanced LIGO detectors. Furthermore, the prototype of a 140 W pre-stabilized laser system for future use in the LIGO observatories is described and characterized.

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Paterson, K., M. J. Lundquist, J. C. Rastinejad, W. Fong, D. J. Sand, J. E. Andrews, R. C. Amaro, et al. "Searches after Gravitational Waves Using ARizona Observatories (SAGUARO): Observations and Analysis from Advanced LIGO/Virgo's Third Observing Run." Astrophysical Journal 912, no. 2 (May 1, 2021): 128. http://dx.doi.org/10.3847/1538-4357/abeb71.

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Abbott, R., H. Abe, F. Acernese, K. Ackley, N. Adhikari, R. X. Adhikari, V. K. Adkins, et al. "Searches for Gravitational Waves from Known Pulsars at Two Harmonics in the Second and Third LIGO-Virgo Observing Runs." Astrophysical Journal 935, no. 1 (May 25, 2022): 1. http://dx.doi.org/10.3847/1538-4357/ac6acf.

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Abstract We present a targeted search for continuous gravitational waves (GWs) from 236 pulsars using data from the third observing run of LIGO and Virgo (O3) combined with data from the second observing run (O2). Searches were for emission from the l = m = 2 mass quadrupole mode with a frequency at only twice the pulsar rotation frequency (single harmonic) and the l = 2, m = 1, 2 modes with a frequency of both once and twice the rotation frequency (dual harmonic). No evidence of GWs was found, so we present 95% credible upper limits on the strain amplitudes h 0 for the single-harmonic search along with limits on the pulsars’ mass quadrupole moments Q 22 and ellipticities ε. Of the pulsars studied, 23 have strain amplitudes that are lower than the limits calculated from their electromagnetically measured spin-down rates. These pulsars include the millisecond pulsars J0437−4715 and J0711−6830, which have spin-down ratios of 0.87 and 0.57, respectively. For nine pulsars, their spin-down limits have been surpassed for the first time. For the Crab and Vela pulsars, our limits are factors of ∼100 and ∼20 more constraining than their spin-down limits, respectively. For the dual-harmonic searches, new limits are placed on the strain amplitudes C 21 and C 22. For 23 pulsars, we also present limits on the emission amplitude assuming dipole radiation as predicted by Brans-Dicke theory.

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Petrov, Polina, Leo P. Singer, Michael W. Coughlin, Vishwesh Kumar, Mouza Almualla, Shreya Anand, Mattia Bulla, Tim Dietrich, Francois Foucart, and Nidhal Guessoum. "Data-driven Expectations for Electromagnetic Counterpart Searches Based on LIGO/Virgo Public Alerts." Astrophysical Journal 924, no. 2 (January 1, 2022): 54. http://dx.doi.org/10.3847/1538-4357/ac366d.

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Abstract Searches for electromagnetic counterparts of gravitational-wave signals have redoubled since the first detection in 2017 of a binary neutron star merger with a gamma-ray burst, optical/infrared kilonova, and panchromatic afterglow. Yet, one LIGO/Virgo observing run later, there has not yet been a second, secure identification of an electromagnetic counterpart. This is not surprising given that the localization uncertainties of events in LIGO and Virgo’s third observing run, O3, were much larger than predicted. We explain this by showing that improvements in data analysis that now allow LIGO/Virgo to detect weaker and hence more poorly localized events have increased the overall number of detections, of which well-localized, gold-plated events make up a smaller proportion overall. We present simulations of the next two LIGO/Virgo/KAGRA observing runs, O4 and O5, that are grounded in the statistics of O3 public alerts. To illustrate the significant impact that the updated predictions can have, we study the follow-up strategy for the Zwicky Transient Facility. Realistic and timely forecasting of gravitational-wave localization accuracy is paramount given the large commitments of telescope time and the need to prioritize which events are followed up. We include a data release of our simulated localizations as a public proposal planning resource for astronomers.

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Acernese, F., M. Agathos, A. Ain, S. Albanesi, A. Allocca, A. Amato, T. Andrade, et al. "The Virgo O3 run and the impact of the environment." Classical and Quantum Gravity 39, no. 23 (November 29, 2022): 235009. http://dx.doi.org/10.1088/1361-6382/ac776a.

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Abstract Sources of geophysical noise (such as wind, sea waves and earthquakes) or of anthropogenic noise impact ground-based gravitational-wave interferometric detectors, causing transient sensitivity worsening and gaps in data taking. During the one year-long third observing run (O3: from April 01, 2019 to March 27, 2020), the Virgo Collaboration collected a statistically significant dataset, used in this article to study the response of the detector to a variety of environmental conditions. We correlated environmental parameters to global detector performance, such as observation range, duty cycle and control losses. Where possible, we identified weaknesses in the detector that will be used to elaborate strategies in order to improve Virgo robustness against external disturbances for the next data taking period, O4, currently planned to start at the end of 2022. The lessons learned could also provide useful insights for the design of the next generation of ground-based interferometers.

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Abbott, R., T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, et al. "Search for Lensing Signatures in the Gravitational-Wave Observations from the First Half of LIGO–Virgo’s Third Observing Run." Astrophysical Journal 923, no. 1 (December 1, 2021): 14. http://dx.doi.org/10.3847/1538-4357/ac23db.

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Abstract We search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo during O3a, the first half of their third observing run. We study: (1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; (2) how the interpretation of individual high-mass events would change if they were found to be lensed; (3) the possibility of multiple images due to strong lensing by galaxies or galaxy clusters; and (4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses.

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Merfeld, Kara. "Search for gravitational-wave transients associated with magnetar bursts during the third Advanced LIGO and Advanced Virgo observing run." Proceedings of the International Astronomical Union 16, S363 (June 2020): 187–90. http://dx.doi.org/10.1017/s1743921322002629.

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AbstractMagnetars are neutron stars with exceptionally strong dipole magnetic fields which are observed to display a range of x-ray flaring behavior, but the flaring mechanism is not well understood. The third observing run of Advanced LIGO and Virgo extended from April 1, 2019 to March 27, 2020, and contained x-ray flares from known magnetar SGR 1935+2154, as well as the newly-discovered magnetar, Swift J1818-1607. We search for gravitational waves coincident with these magnetar flares with minimally modeled, coherent searches which specifically target both short-duration gravitational waves produced by excited f-modes in the magnetar’s core, as well as long-duration gravitational waves motivated by the Quasi-Periodic Oscillations observed in the tails of giant flares. In this talk, we report on the methods and sensitivity estimates of there searches, and the astrophysical implications.

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Fletcher, C., J. Wood, R. Hamburg, P. Veres, C. M. Hui, E. Bissaldi, M. S. Briggs, et al. "A Joint Fermi-GBM and Swift-BAT Analysis of Gravitational-wave Candidates from the Third Gravitational-wave Observing Run." Astrophysical Journal 964, no. 2 (March 27, 2024): 149. http://dx.doi.org/10.3847/1538-4357/ad1eed.

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Abstract We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational-wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM onboard triggers and subthreshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift-BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma rays from binary black hole mergers.

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Singh, K. P., V. Girish, M. Pavana, Jan-Uwe Ness, G. C. Anupama, and M. Orio. "AstroSat soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst." Monthly Notices of the Royal Astronomical Society 501, no. 1 (October 29, 2020): 36–49. http://dx.doi.org/10.1093/mnras/staa3303.

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ABSTRACT Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the symbiotic recurrent nova V3890 Sgr. The first observing run, 8.1–9.9 d after the outburst, initially showed a stable intensity level with a hard X-ray spectrum that we attribute to shocks between the nova ejecta and the pre-existing stellar companion. On day 8.57, the first, weak, signs appeared of supersoft source (SSS) emission powered by residual burning on the surface of the white dwarf. The SSS emission was observed to be highly variable on time-scales of hours. After day 8.9, the SSS component was more stable and brighter. In the second observing run, on days 15.9–19.6 after the outburst, the SSS component was even brighter but still highly variable. The SSS emission was observed to fade significantly during days 16.8–17.8 followed by re-brightening. Meanwhile, the shock component was stable, leading to increase in hardness ratio during the period of fading. AstroSat and XMM–Newton observations have been used to study the spectral properties of V3890 Sgr to draw quantitative conclusions even if their drawback is model dependent. We used the xspec to fit spectral models of plasma emission, and the best fits are consistent with the elemental abundances being lower during the second observing run compared to the first for spectra ≥1 keV. The SSS emission is well fitted by non-local thermal equilibrium model atmosphere used for white dwarfs. The resulting spectral parameters, however, are subject to systematic uncertainties such as completeness of atomic data.

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Basak, S., A. Ganguly, K. Haris, S. Kapadia, A. K. Mehta, and P. Ajith. "Constraints on Compact Dark Matter from Gravitational Wave Microlensing." Astrophysical Journal Letters 926, no. 2 (February 1, 2022): L28. http://dx.doi.org/10.3847/2041-8213/ac4dfa.

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Abstract If a significant fraction of dark matter is in the form of compact objects, they will cause microlensing effects in the gravitational wave signals observable by LIGO and Virgo. From the nonobservation of microlensing signatures in the binary black hole events from the first two observing runs and the first half of the third observing run, we constrain the fraction of compact dark matter in the mass range 102–105 M ⊙ to be less than ≃50%–80% (details depend on the assumed source population properties and the Bayesian priors). These modest constraints will be significantly improved in the next few years with the expected detection of thousands of binary black hole events, providing a new avenue to probe the nature of dark matter.

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Di Girolamo, T. "Search for gravitational waves associated with Gamma Ray Bursts during the LIGO-Virgo run O3b." Journal of Physics: Conference Series 2429, no. 1 (February 1, 2023): 012037. http://dx.doi.org/10.1088/1742-6596/2429/1/012037.

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Abstract We present the search for gravitational waves associated with Gamma Ray Bursts (GRBs) detected by the Fermi and Swift satellites during the second part of the third observing run (O3b) of Advanced LIGO and Advanced Virgo, from 2019 November 1 to 2020 March 27. This search is carried out with two different methods, a modelled search targeting compact binary mergers with at least one neutron star, which is used for 17 short GRBs, and a search for generic transients, used for all the 86 GRBs. We find no statistically significant gravitational wave signal associated with any of these GRBs. Considering several source types and signal morphologies, we set lower bounds on the estimated distance to each GRB.

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Allocca, Annalisa, Diego Bersanetti, Julia Casanueva Diaz, Camilla De Rossi, Maddalena Mantovani, Alain Masserot, Loïc Rolland, et al. "Interferometer Sensing and Control for the Advanced Virgo Experiment in the O3 Scientific Run." Galaxies 8, no. 4 (December 8, 2020): 85. http://dx.doi.org/10.3390/galaxies8040085.

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Advanced Virgo is a 2nd-generation laser interferometer based in Cascina (Italy) aimed at the detection of gravitational waves (GW) from astrophysical sources. Together with the two USA-based LIGO interferometers they constitute a network which operates in coincidence. The three detectors observed the sky simultaneously during the last part of the second Observing Run (O2) in August 2017, and this led to two paramount discoveries: the first three-detector observation of gravitational waves emitted from the coalescence of a binary black hole system (GW170814), and the first detection ever of gravitational waves emitted from the coalescence of a binary neutron star system (GW170817). Coincident data taking was re-started for the third Observing Run (O3), which started on 1st April 2019 and lasted almost one year. This paper will describe the new techniques implemented for the longitudinal controls with respect to the ones already in use during O2. Then, it will present an extensive description of the full scheme of the angular controls of the interferometer, focusing on the different control strategies that are in place in the different stages of the lock acquisition procedure, which is the complex sequence of operations by which an uncontrolled, “free” laser interferometer is brought to the final working point, which allows the detector to reach the best sensitivity.

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Abbott, R., T. D. Abbott, F. Acernese, K. Ackley, C. Adams, N. Adhikari, R. X. Adhikari, et al. "Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run." Astrophysical Journal 932, no. 2 (June 1, 2022): 133. http://dx.doi.org/10.3847/1538-4357/ac6ad0.

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Abstract Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo’s third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours–months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets.

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Abbott, R., T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, et al. "Searches for Continuous Gravitational Waves from Young Supernova Remnants in the Early Third Observing Run of Advanced LIGO and Virgo." Astrophysical Journal 921, no. 1 (November 1, 2021): 80. http://dx.doi.org/10.3847/1538-4357/ac17ea.

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Lundquist, M. J., K. Paterson, W. Fong, D. J. Sand, J. E. Andrews, I. Shivaei, P. N. Daly, et al. "Searches after Gravitational Waves Using ARizona Observatories (SAGUARO): System Overview and First Results from Advanced LIGO/Virgo’s Third Observing Run." Astrophysical Journal 881, no. 2 (August 15, 2019): L26. http://dx.doi.org/10.3847/2041-8213/ab32f2.

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Unatlokov, I. B., I. M. Dzaparova, M. G. Kostyuk, M. M. Kochkarov, A. N. Kurenya, Yu F. Novoseltsev, R. V. Novoseltseva, V. B. Petkov, P. S. Striganov, and A. F. Yanin. "Search for neutrino counterparts of LIGO/Virgo gravitational-wave events." Journal of Physics: Conference Series 2156, no. 1 (December 1, 2021): 012142. http://dx.doi.org/10.1088/1742-6596/2156/1/012142.

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Abstract The LIGO/Virgo collaborations have reported the results of their searches for gravitational-waves from the first half of their third observing run. 39 events were combined into the second Gravitational-Wave Transient Catalog (GWTC-2), reaching the total number of 50. In addition to these, two neutron star - black hole merger events were also confirmed. The search for neutrino counterparts of LIGO/Virgo gravitational-wave events was performed on the Baksan Underground Scintillation Telescope. The processing algorithm and the results of the counterpart search are described.

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Acernese, F., M. Agathos, A. Ain, S. Albanesi, A. Allocca, A. Amato, T. Andrade, et al. "Calibration of advanced Virgo and reconstruction of the detector strain h(t) during the observing run O3." Classical and Quantum Gravity 39, no. 4 (January 21, 2022): 045006. http://dx.doi.org/10.1088/1361-6382/ac3c8e.

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Abstract The three advanced Virgo and LIGO gravitational wave detectors participated to the third observing run (O3) between 1 April 2019 15:00 UTC and 27 March 2020 17:00 UTC, leading to several gravitational wave detections per month. This paper describes the advanced Virgo detector calibration and the reconstruction of the detector strain h(t) during O3, as well as the estimation of the associated uncertainties. For the first time, the photon calibration technique as been used as reference for Virgo calibration, which allowed to cross-calibrate the strain amplitude of the Virgo and LIGO detectors. The previous reference, so-called free swinging Michelson technique, has still been used but as an independent cross-check. h(t) reconstruction and noise subtraction were processed online, with good enough quality to prevent the need for offline reprocessing, except for the two last weeks of September 2019. The uncertainties for the reconstructed h(t) strain, estimated in this paper in a 20–2000 Hz frequency band, are frequency independent: 5% in amplitude, 35 mrad in phase and 10 μs in timing, with the exception of larger uncertainties around 50 Hz.

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Coughlin, Michael W., Tim Dietrich, Sarah Antier, Mouza Almualla, Shreya Anand, Mattia Bulla, Francois Foucart, et al. "Implications of the search for optical counterparts during the second part of the Advanced LIGO’s and Advanced Virgo’s third observing run: lessons learned for future follow-up observations." Monthly Notices of the Royal Astronomical Society 497, no. 1 (July 6, 2020): 1181–96. http://dx.doi.org/10.1093/mnras/staa1925.

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ABSTRACT Joint multimessenger observations with gravitational waves and electromagnetic (EM) data offer new insights into the astrophysical studies of compact objects. The third Advanced LIGO and Advanced Virgo observing run began on 2019 April 1; during the 11 months of observation, there have been 14 compact binary systems candidates for which at least one component is potentially a neutron star. Although intensive follow-up campaigns involving tens of ground and space-based observatories searched for counterparts, no EM counterpart has been detected. Following on a previous study of the first six months of the campaign, we present in this paper the next five months of the campaign from 2019 October to 2020 March. We highlight two neutron star–black hole candidates (S191205ah and S200105ae), two binary neutron star candidates (S191213g and S200213t), and a binary merger with a possible neutron star and a ‘MassGap’ component, S200115j. Assuming that the gravitational-wave (GW) candidates are of astrophysical origin and their location was covered by optical telescopes, we derive possible constraints on the matter ejected during the events based on the non-detection of counterparts. We find that the follow-up observations during the second half of the third observing run did not meet the necessary sensitivity to constrain the source properties of the potential GW candidate. Consequently, we suggest that different strategies have to be used to allow a better usage of the available telescope time. We examine different choices for follow-up surveys to optimize sky localization coverage versus observational depth to understand the likelihood of counterpart detection.

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Abbott, R., H. Abe, F. Acernese, K. Ackley, N. Adhikari, R. X. Adhikari, V. K. Adkins, et al. "Search for Gravitational-wave Transients Associated with Magnetar Bursts in Advanced LIGO and Advanced Virgo Data from the Third Observing Run." Astrophysical Journal 966, no. 1 (April 30, 2024): 137. http://dx.doi.org/10.3847/1538-4357/ad27d3.

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Abstract Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant flares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and long-duration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA’s third observation run. These 13 bursts come from two magnetars, SGR 1935+2154 and Swift J1818.0−1607. We also include three other electromagnetic burst events detected by Fermi-GBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant flares were detected during the analysis period. We find no evidence of gravitational waves associated with any of these 16 bursts. We place upper limits on the rms of the integrated incident gravitational-wave strain that reach 3.6 × 10−23 / Hz at 100 Hz for the short-duration search and 1.1 × 10−22 / Hz at 450 Hz for the long-duration search. For a ringdown signal at 1590 Hz targeted by the short-duration search the limit is set to 2.3 × 10−22 / Hz . Using the estimated distance to each magnetar, we derive upper limits on the emitted gravitational-wave energy of 1.5 × 1044 erg (1.0 × 1044 erg) for SGR 1935+2154 and 9.4 × 1043 erg (1.3 × 1044 erg) for Swift J1818.0−1607, for the short-duration (long-duration) search. Assuming isotropic emission of electromagnetic radiation of the burst fluences, we constrain the ratio of gravitational-wave energy to electromagnetic energy for bursts from SGR 1935+2154 with the available fluence information. The lowest of these ratios is 4.5 × 103.

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Wang, Hongli, Xiang-Yu Huang, and Yongsheng Chen. "An Observing System Simulation Experiment for the Impact of MTG Candidate Infrared Sounding Mission on Regional Forecasts: System Development and Preliminary Results." ISRN Meteorology 2013 (April 9, 2013): 1–18. http://dx.doi.org/10.1155/2013/971501.

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An Observing System Simulation Experiment (OSSE) was designed and developed to assess the potential benefit of the Infrared Sounding on the Meteosat Third Generation (MTG-IRS) geostationary meteorological satellite system to regional forecasts. In the proposed OSSE framework, two different models, namely, the MM5 and WRF models, were used in a nature run and data assimilation experiments, respectively, to reduce the identical twin problem. The 5-day nature run, which included three convective storms that occurred during the period from 11 to 16 June 2002 over US Great Plains, was generated using MM5 with a 4 km. The simulated “conventional” observations and MTG-IRS retrieved temperature and humidity profiles, produced from the nature run, were then assimilated into the WRF model. Calibration experiments showed that assimilating real or simulated “conventional” observations yielded similar error statistics in analyses and forecasts, indicating that the developed OSSE system worked well. On average, the MTG-IRS retrieved profiles had positive impact on the analyses and forecasts. The analyses reduced the errors not only in the temperature and the humidity fields but in the horizontal wind fields as well. The forecast skills of these variables were improved up to 12 hours. The 18 h precipitation forecast accuracy was also increased.

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Safarzadeh, Mohammadtaher, and Daniel Wysocki. "A Common Origin for Low-mass Ratio Events Observed by LIGO and Virgo in the First Half of the Third Observing Run." Astrophysical Journal 907, no. 2 (January 27, 2021): L24. http://dx.doi.org/10.3847/2041-8213/abd8c7.

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Abdalla, H., F. Aharonian, F. Ait Benkhali, E. O. Angüner, H. Ashkar, M. Backes, V. Baghmanyan, et al. "H.E.S.S. Follow-up Observations of Binary Black Hole Coalescence Events during the Second and Third Gravitational-wave Observing Runs of Advanced LIGO and Advanced Virgo." Astrophysical Journal 923, no. 1 (December 1, 2021): 109. http://dx.doi.org/10.3847/1538-4357/ac2e04.

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Abstract We report on the observations of four well-localized binary black hole (BBH) mergers by the High Energy Stereoscopic System (H.E.S.S.) during the second and third observing runs of Advanced LIGO and Advanced Virgo, O2 and O3. H.E.S.S. can observe 20 deg2 of the sky at a time and follows up gravitational-wave (GW) events by “tiling” localization regions to maximize the covered localization probability. During O2 and O3, H.E.S.S. observed large portions of the localization regions, between 35% and 75%, for four BBH mergers (GW170814, GW190512_180714, GW190728_064510, and S200224ca). For these four GW events, we find no significant signal from a pointlike source in any of the observations, and we set upper limits on the very high energy (>100 GeV) γ-ray emission. The 1–10 TeV isotropic luminosity of these GW events is below 1045 erg s−1 at the times of the H.E.S.S. observations, around the level of the low-luminosity GRB 190829A. Assuming no changes are made to how follow-up observations are conducted, H.E.S.S. can expect to observe over 60 GW events per year in the fourth GW observing run, O4, of which eight would be observable with minimal latency.

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Zhu, Jin-Ping, Shichao Wu, Ying Qin, Bing Zhang, He Gao, and Zhoujian Cao. "Population Properties of Gravitational-wave Neutron Star–Black Hole Mergers." Astrophysical Journal 928, no. 2 (April 1, 2022): 167. http://dx.doi.org/10.3847/1538-4357/ac540c.

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Abstract Over the course of the third observing run of the LIGO–Virgo–KAGRA Collaboration, several gravitational-wave (GW) neutron star–black hole (NSBH) candidates have been announced. By assuming that these candidates are real signals with astrophysical origins, we analyze the population properties of the mass and spin distributions for GW NSBH mergers. We find that the primary BH mass distribution of NSBH systems, whose shape is consistent with that inferred from the GW binary BH (BBH) primaries, can be well described as a power law with an index of α = 4.8 − 2.8 + 4.5 plus a high-mass Gaussian component peaking at ∼ 33 − 9 + 14 M ⊙ . The NS mass spectrum could be shaped as a nearly flat distribution between ∼1.0 and 2.1 M ⊙. The constrained NS maximum mass agrees with that inferred from NSs in our Galaxy. If GW190814 and GW200210 are NSBH mergers, the posterior results of the NS maximum mass would be always larger than ∼2.5 M ⊙ and significantly deviate from that inferred in Galactic NSs. The effective inspiral spin and effective precession spin of GW NSBH mergers are measured to potentially have near-zero distributions. The negligible spins for GW NSBH mergers imply that most events in the universe should be plunging events, which support the standard isolated formation channel of NSBH binaries. More NSBH mergers to be discovered in the fourth observing run would help to more precisely model the population properties of cosmological NSBH mergers.

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Mo, Geoffrey, Rahul Jayaraman, Michael Fausnaugh, Erik Katsavounidis, George R. Ricker, and Roland Vanderspek. "Searching for Gravitational-wave Counterparts Using the Transiting Exoplanet Survey Satellite." Astrophysical Journal Letters 948, no. 1 (April 26, 2023): L3. http://dx.doi.org/10.3847/2041-8213/acca70.

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Abstract In 2017, the LIGO and Virgo gravitational-wave (GW) detectors, in conjunction with electromagnetic (EM) astronomers, observed the first GW multimessenger astrophysical event, the binary neutron star (BNS) merger GW170817. This marked the beginning of a new era in multimessenger astrophysics. To discover further GW multimessenger events, we explore the synergies between the Transiting Exoplanet Survey Satellite (TESS) and GW observations triggered by the LIGO–Virgo–KAGRA Collaboration (LVK) detector network. TESS's extremely wide field of view (∼2300 deg2) means that it could overlap with large swaths of GW localizations, which often span hundreds of square degrees or more. In this work, we use a recently developed transient detection pipeline to search TESS data collected during the LVK’s third observing run, O3, for any EM counterparts. We find no obvious counterparts brighter than about 17th magnitude in the TESS bandpass. Additionally, we present end-to-end simulations of BNS mergers, including their detection in GWs and simulations of light curves, to identify TESS's kilonova discovery potential for the LVK's next observing run (O4). In the most optimistic case, TESS will observe up to one GW-found BNS merger counterpart per year. However, TESS may also find up to five kilonovae that did not trigger the LVK network, emphasizing that EM-triggered GW searches may play a key role in future kilonova detections. We also discuss how TESS can help place limits on EM emission from binary black hole mergers and rapidly exclude large sky areas for poorly localized GW events.

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Stiskalek, Richard, John Veitch, and Chris Messenger. "Are stellar-mass binary black hole mergers isotropically distributed?" Monthly Notices of the Royal Astronomical Society 501, no. 1 (November 21, 2020): 970–77. http://dx.doi.org/10.1093/mnras/staa3613.

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ABSTRACT The Advanced LIGO and Advanced Virgo gravitational wave detectors have detected a population of binary black hole mergers in their first two observing runs. For each of these events, we have been able to associate a potential sky location region represented as a probability distribution on the sky. Thus, at this point we may begin to ask the question of whether this distribution agrees with the isotropic model of the Universe, or if there is any evidence of anisotropy. We perform Bayesian model selection between an isotropic and a simple anisotropic model, taking into account the anisotropic selection function caused by the underlying antenna patterns and sensitivity of the interferometers over the sidereal day. We find an inconclusive Bayes factor of 1.3: 1, suggesting that the data from the first two observing runs are insufficient to pick a preferred model. However, the first detections were mostly poorly localized in the sky (before the Advanced Virgo joined the network), spanning large portions of the sky and hampering detection of potential anisotropy. It will be appropriate to repeat this analysis with events from the recent third LIGO observational run and a more sophisticated cosmological model.

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Frick, Mira, Ryota Iijima, and Yuhta Ishii. "Misinterpreting Others and the Fragility of Social Learning." Econometrica 88, no. 6 (2020): 2281–328. http://dx.doi.org/10.3982/ecta16981.

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We exhibit a natural environment, social learning among heterogeneous agents, where even slight misperceptions can have a large negative impact on long‐run learning outcomes. We consider a population of agents who obtain information about the state of the world both from initial private signals and by observing a random sample of other agents' actions over time, where agents' actions depend not only on their beliefs about the state but also on their idiosyncratic types (e.g., tastes or risk attitudes). When agents are correct about the type distribution in the population, they learn the true state in the long run. By contrast, we show, first, that even arbitrarily small amounts of misperception about the type distribution can generate extreme breakdowns of information aggregation, where in the long run all agents incorrectly assign probability 1 to some fixed state of the world, regardless of the true underlying state. Second, any misperception of the type distribution leads long‐run beliefs and behavior to vary only coarsely with the state, and we provide systematic predictions for how the nature of misperception shapes these coarse long‐run outcomes. Third, we show that how fragile information aggregation is against misperception depends on the richness of agents' payoff‐relevant uncertainty; a design implication is that information aggregation can be improved by simplifying agents' learning environment. The key feature behind our findings is that agents' belief‐updating becomes “decoupled” from the true state over time. We point to other environments where this feature is present and leads to similar fragility results.

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Abbott, R., T. D. Abbott, F. Acernese, K. Ackley, C. Adams, N. Adhikari, R. X. Adhikari, et al. "Search for Gravitational Waves Associated with Fast Radio Bursts Detected by CHIME/FRB during the LIGO–Virgo Observing Run O3a." Astrophysical Journal 955, no. 2 (September 28, 2023): 155. http://dx.doi.org/10.3847/1538-4357/acd770.

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Abstract We search for gravitational-wave (GW) transients associated with fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project, during the first part of the third observing run of Advanced LIGO and Advanced Virgo (2019 April 1 15:00 UTC–2019 October 1 15:00 UTC). Triggers from 22 FRBs were analyzed with a search that targets both binary neutron star (BNS) and neutron star–black hole (NSBH) mergers. A targeted search for generic GW transients was conducted on 40 FRBs. We find no significant evidence for a GW association in either search. Given the large uncertainties in the distances of our FRB sample, we are unable to exclude the possibility of a GW association. Assessing the volumetric event rates of both FRB and binary mergers, an association is limited to 15% of the FRB population for BNS mergers or 1% for NSBH mergers. We report 90% confidence lower bounds on the distance to each FRB for a range of GW progenitor models and set upper limits on the energy emitted through GWs for a range of emission scenarios. We find values of order 1051–1057 erg for models with central GW frequencies in the range 70–3560 Hz. At the sensitivity of this search, we find these limits to be above the predicted GW emissions for the models considered. We also find no significant coincident detection of GWs with the repeater, FRB 20200120E, which is the closest known extragalactic FRB.

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Antokhin, Igor I., Jean-François Bertrand, Robert Lamontagne, and Anthony F. J. Moffat. "The absence of a short period in the WN5 star EZ Canis Majoris." Symposium - International Astronomical Union 163 (1995): 56–57. http://dx.doi.org/10.1017/s0074180900201599.

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Several suggestion have been put forward to explain the 3.d766 periodicity of EZ CMa (WR6): (i) WR+c system; (ii) rotating single WR star; (iii) pulsations (non—radial (NRP) or radial) with frequency reduced by some kind of filtering in the wind. In this paper, we report on a photometric investigation based on a long continuous observing run, in an attempt to verify whether EZ CMa does in fact show a unique periodicity. In particular, this work was motivated by the claim by Gosset & Vreux (1987), based on the data from Lamontagne et al. (1986, hereafter LML), that EZ CMa may have a shorter period besides the one at 3.d766, a frequency close to but not equal to the third harmonic of the 3.d766 period.

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Antier, S., S. Agayeva, M. Almualla, S. Awiphan, A. Baransky, K. Barynova, S. Beradze, et al. "GRANDMA observations of advanced LIGO’s and advanced Virgo’s third observational campaign." Monthly Notices of the Royal Astronomical Society 497, no. 4 (June 26, 2020): 5518–39. http://dx.doi.org/10.1093/mnras/staa1846.

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ABSTRACT GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of 25 telescopes of different sizes, including both photometric and spectroscopic facilities. The network aims to coordinate follow-up observations of gravitational-wave (GW) candidate alerts, especially those with large localization uncertainties, to reduce the delay between the initial detection and the optical confirmation. In this paper, we detail GRANDMA’s observational performance during Advanced LIGO/Advanced Virgo Observing Run 3 (O3), focusing on the second part of O3; this includes summary statistics pertaining to coverage and possible astrophysical origin of the candidates. To do so, we quantify our observation efficiency in terms of delay between GW candidate trigger time, observations, and the total coverage. Using an optimized and robust coordination system, GRANDMA followed-up about 90 per cent of the GW candidate alerts, that is 49 out of 56 candidates. This led to coverage of over 9000 deg2 during O3. The delay between the GW candidate trigger and the first observation was below 1.5 h for 50 per cent of the alerts. We did not detect any electromagnetic counterparts to the GW candidates during O3, likely due to the very large localization areas (on average thousands of degrees squares) and relatively large distance of the candidates (above 200 Mpc for 60 per cent of binary neutron star, BNS candidates). We derive constraints on potential kilonova properties for two potential BNS coalescences (GW190425 and S200213t), assuming that the events’ locations were imaged.

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Owen, Benjamin J., Lee Lindblom, Luciano Soares Pinheiro, and Binod Rajbhandari. "Improved Upper Limits on Gravitational-wave Emission from NS 1987A in SNR 1987A." Astrophysical Journal Letters 962, no. 2 (February 1, 2024): L23. http://dx.doi.org/10.3847/2041-8213/ad2263.

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Abstract We report on a new search for continuous gravitational waves from NS 1987A, the neutron star born in SN 1987A, using open data from Advanced LIGO and Virgo’s third observing run (O3). The search covered frequencies from 35–1050 Hz, more than 5 times the band of the only previous gravitational-wave search to constrain NS 1987A. Our search used an improved code and coherently integrated from 5.10 to 14.85 days depending on frequency. No astrophysical signals were detected. By expanding the frequency range and using O3 data, this search improved on strain upper limits from the previous search and was sensitive at the highest frequencies to ellipticities of 1.6 × 10−5 and r-mode amplitudes of 4.4 × 10−4, both an order of magnitude improvement over the previous search and both well within the range of theoretical predictions.

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Journal articles on the topic 'Third observing run'

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