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arXiv · 2507.12282

All-sky search for long-duration gravitational-wave transients in the first part of the fourth LIGO-Virgo-KAGRA Observing run

The LIGO Scientific Collaboration·the Virgo Collaboration·the KAGRA Collaboration·A. G. Abac·I. Abouelfettouh·F. Acernese·K. Ackley·C. Adamcewicz·S. Adhicary·D. Adhikari·N. Adhikari·R. X. Adhikari·V. K. Adkins·S. Afroz·A. Agapito·D. Agarwal·M. Agathos·N. Aggarwal·S. Aggarwal·O. D. Aguiar·I. -L. Ahrend·L. Aiello·A. Ain·P. Ajith·T. Akutsu·S. Albanesi·W. Ali·S. Al-Kershi·C. Alléné·A. Allocca·S. Al-Shammari·P. A. Altin·S. Alvarez-Lopez·W. Amar·O. Amarasinghe·A. Amato·F. Amicucci·C. Amra·A. Ananyeva·S. B. Anderson·W. G. Anderson·M. Andia·M. Ando·M. Andrés-Carcasona·T. Andrić·J. Anglin·S. Ansoldi·J. M. Antelis·S. Antier·M. Aoumi·E. Z. Appavuravther·S. Appert·S. K. Apple·K. Arai·A. Araya·M. C. Araya·M. Arca Sedda·J. S. Areeda·N. Aritomi·F. Armato·S. Armstrong·N. Arnaud·M. Arogeti·S. M. Aronson·K. G. Arun·G. Ashton·Y. Aso·L. Asprea·M. Assiduo·S. Assis de Souza Melo·S. M. Aston·P. Astone·F. Attadio·F. Aubin·K. AultONeal·G. Avallone·E. A. Avila·S. Babak·C. Badger·S. Bae·S. Bagnasco·L. Baiotti·R. Bajpai·T. Baka·A. M. Baker·K. A. Baker·T. Baker·G. Baldi·N. Baldicchi·M. Ball·G. Ballardin·S. W. Ballmer·S. Banagiri·B. Banerjee·D. Bankar·T. M. Baptiste·P. Baral·M. Baratti·J. C. Barayoga·B. C. Barish
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Abstract

We present an all-sky search for long-duration gravitational waves (GWs) from the first part of the LIGO-Virgo-KAGRA fourth observing run (O4), called O4a and comprising data taken between 24 May 2023 and 16 January 2024. The GW signals targeted by this search are the so-called "long-duration" (> 1 s) transients expected from a variety of astrophysical processes, including non-axisymmetric deformations in magnetars or eccentric binary coalescences. We make minimal assumptions on the emitted GW waveforms in terms of morphologies and durations. Overall, our search targets signals with durations ~1-1000 s and frequency content in the range 16-2048 Hz. In the absence of significant detections, we report the sensitivity limits of our search in terms of root-sum-square signal amplitude (hrss) of reference waveforms. These limits improve upon the results from the third LIGO-Virgo-KAGRA observing run (O3) by about 30% on average. Moreover, this analysis demonstrates substantial progress in our ability to search for long-duration GW signals owing to enhancements in pipeline detection efficiencies. As detector sensitivities continue to advance and observational runs grow longer, unmodeled long-duration searches will increasingly be able to explore a range of compelling astrophysical scenarios involving neutron stars and black holes.

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The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, A. G. Abac, I. Abouelfettouh, F. Acernese, K. Ackley, C. Adamcewicz, S. Adhicary, D. Adhikari, N. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I. -L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, W. Ali, S. Al-Kershi, C. Alléné, A. Allocca, S. Al-Shammari, P. A. Altin, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, M. Andrés-Carcasona, T. Andrić, J. Anglin, S. Ansoldi, J. M. Antelis, S. Antier, M. Aoumi, E. Z. Appavuravther, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, M. Arca Sedda, J. S. Areeda, N. Aritomi, F. Armato, S. Armstrong, N. Arnaud, M. Arogeti, S. M. Aronson, K. G. Arun, G. Ashton, Y. Aso, L. Asprea, M. Assiduo, S. Assis de Souza Melo, S. M. Aston, P. Astone, F. Attadio, F. Aubin, K. AultONeal, G. Avallone, E. A. Avila, S. Babak, C. Badger, S. Bae, S. Bagnasco, L. Baiotti, R. Bajpai, T. Baka, A. M. Baker, K. A. Baker, T. Baker, G. Baldi, N. Baldicchi, M. Ball, G. Ballardin, S. W. Ballmer, S. Banagiri, B. Banerjee, D. Bankar, T. M. Baptiste, P. Baral, M. Baratti, J. C. Barayoga, B. C. Barish. 2025-07-16. All-sky search for long-duration gravitational-wave transients in the first part of the fourth LIGO-Virgo-KAGRA Observing run. https://doi.org/10.1103/83j3-pgk1

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