Advanced LIGO detector performance in the fourth observing run
Abstract
On May 24th, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 Mpc and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.
Cite
@article{arxiv.2411.14607,
title = {Advanced LIGO detector performance in the fourth observing run},
author = {E. Capote and W. Jia and N. Aritomi and M. Nakano and V. Xu and R. Abbott and I. Abouelfettouh and R. X. Adhikari and A. Ananyeva and S. Appert and S. K. Apple and K. Arai and S. M. Aston and M. Ball and S. W. Ballmer and D. Barker and L. Barsotti and B. K. Berger and J. Betzwieser and D. Bhattacharjee and G. Billingsley and S. Biscans and C. D. Blair and N. Bode and E. Bonilla and V. Bossilkov and A. Branch and A. F. Brooks and D. D. Brown and J. Bryant and C. Cahillane and H. Cao and F. Clara and J. Collins and C. M. Compton and R. Cottingham and D. C. Coyne and R. Crouch and J. Csizmazia and A. Cumming and L. P. Dartez and D. Davis and N. Demos and E. Dohmen and J. C. Driggers and S. E. Dwyer and A. Effler and A. Ejlli and T. Etzel and M. Evans and J. Feicht and R. Frey and W. Frischhertz and P. Fritschel and V. V. Frolov and M. Fuentes-Garcia and P. Fulda and M. Fyffe and D. Ganapathy and B. Gateley and T. Gayer and J. A. Giaime and K. D. Giardina and J. Glanzer and E. Goetz and R. Goetz and A. W. Goodwin-Jones and S. Gras and C. Gray and D. Griffith and H. Grote and T. Guidry and J. Gurs and E. D. Hall and J. Hanks and J. Hanson and M. C. Heintze and A. F. Helmling-Cornell and N. A. Holland and D. Hoyland and H. Y. Huang and Y. Inoue and A. L. James and A. Jamies and A. Jennings and D. H. Jones and H. B. Kabagoz and S. Karat and S. Karki and M. Kasprzack and K. Kawabe and N. Kijbunchoo and P. J. King and J. S. Kissel and K. Komori and A. Kontos and Rahul Kumar and K. Kuns and M. Landry and B. Lantz and M. Laxen and K. Lee and M. Lesovsky and F. Llamas Villarreal and M. Lormand and H. A. Loughlin and R. Macas and M. MacInnis and C. N. Makarem and B. Mannix and G. L. Mansell and R. M. Martin and K. Mason and F. Matichard and N. Mavalvala and N. Maxwell and G. McCarrol and R. McCarthy and D. E. McClelland and S. McCormick and T. McRae and F. Mera and E. L. Merilh and F. Meylahn and R. Mittleman and D. Moraru and G. Moreno and A. Mullavey and T. J. N. Nelson and A. Neunzert and J. Notte and J. Oberling and T. OHanlon and C. Osthelder and D. J. Ottaway and H. Overmier and W. Parker and O. Patane and A. Pele and H. Pham and M. Pirello and J. Pullin and V. Quetschke and K. E. Ramirez and K. Ransom and J. Reyes and J. W. Richardson and M. Robinson and J. G. Rollins and C. L. Romel and J. H. Romie and M. P. Ross and K. Ryan and T. Sadecki and A. Sanchez and E. J. Sanchez and L. E. Sanchez and R. L. Savage and D. Schaetzl and M. G. Schiworski and R. Schnabel and R. M. S. Schofield and E. Schwartz and D. Sellers and T. Shaffer and R. W. Short and D. Sigg and B. J. J. Slagmolen and C. Soike and S. Soni and V. Srivastava and L. Sun and D. B. Tanner and M. Thomas and P. Thomas and K. A. Thorne and M. R. Todd and C. I. Torrie and G. Traylor and A. S. Ubhi and G. Vajente and J. Vanosky and A. Vecchio and P. J. Veitch and A. M. Vibhute and E. R. G. von Reis and J. Warner and B. Weaver and R. Weiss and C. Whittle and B. Willke and C. C. Wipf and J. L. Wright and H. Yamamoto and L. Zhang and M. E. Zucker},
journal= {arXiv preprint arXiv:2411.14607},
year = {2025}
}
Comments
26 pages, 18 figures