A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo

Most observed neutron stars have masses around 1.4 M _⊙ , consistent with current formation mechanisms. To date, no subsolar-mass neutron star has been observed. Observing one would provide crucial constraints on the nuclear equation of state, unveil a new neutron star population, and advance unders...

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Main Authors: Keisi Kacanja, Alexander H. Nitz
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adc9a5
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author Keisi Kacanja
Alexander H. Nitz
author_facet Keisi Kacanja
Alexander H. Nitz
author_sort Keisi Kacanja
collection DOAJ
description Most observed neutron stars have masses around 1.4 M _⊙ , consistent with current formation mechanisms. To date, no subsolar-mass neutron star has been observed. Observing one would provide crucial constraints on the nuclear equation of state, unveil a new neutron star population, and advance understanding of their formation mechanisms. We present the first targeted search for tidally deformed subsolar-mass binary neutron stars (BNSs), with primary masses ranging from 0.1 to 2 M _⊙ and secondary masses from 0.1 to 1 M _⊙ , using data from the third observing run of the Advanced LIGO and Virgo gravitational-wave detectors. We account for the tidal deformabilities of up to O (10 ^4 ) of these systems, as low-mass neutron stars are more easily distorted by their companions. Previous searches that neglect tidal deformability lose sensitivity to low-mass sources, potentially missing more than ∼30% of detectable signals from a system with a chirp mass of 0.6 M _⊙ binaries. No statistically significant detections were made. In the absence of a detection, we place a 90% confidence upper limit on the local merger rate for subsolar BNSs, constraining it to be <6.4 × 10 ^4 Gpc ^−3 yr ^−1 for a chirp mass of 0.2 M _⊙ and <2.2 × 10 ^3 Gpc ^−3 yr ^−1 for 0.7 M _⊙ . With future upgrades to detector sensitivity, development of next-generation detectors, and ongoing improvements in search pipelines, constraints on the minimum mass of neutron stars will improve, providing the potential to constrain the nuclear equation of state, reveal new insights into neutron star formation channels, and potentially identify new classes of stars.
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spelling doaj-art-1edb54d850cf46c7a9ebe40e0f3826022025-08-20T03:53:42ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198416110.3847/1538-4357/adc9a5A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and VirgoKeisi Kacanja0https://orcid.org/0009-0004-9167-7769Alexander H. Nitz1https://orcid.org/0000-0002-1850-4587Department of Physics, Syracuse University , Syracuse, NY 13244, USA ; kkacanja@syr.eduDepartment of Physics, Syracuse University , Syracuse, NY 13244, USA ; kkacanja@syr.eduMost observed neutron stars have masses around 1.4 M _⊙ , consistent with current formation mechanisms. To date, no subsolar-mass neutron star has been observed. Observing one would provide crucial constraints on the nuclear equation of state, unveil a new neutron star population, and advance understanding of their formation mechanisms. We present the first targeted search for tidally deformed subsolar-mass binary neutron stars (BNSs), with primary masses ranging from 0.1 to 2 M _⊙ and secondary masses from 0.1 to 1 M _⊙ , using data from the third observing run of the Advanced LIGO and Virgo gravitational-wave detectors. We account for the tidal deformabilities of up to O (10 ^4 ) of these systems, as low-mass neutron stars are more easily distorted by their companions. Previous searches that neglect tidal deformability lose sensitivity to low-mass sources, potentially missing more than ∼30% of detectable signals from a system with a chirp mass of 0.6 M _⊙ binaries. No statistically significant detections were made. In the absence of a detection, we place a 90% confidence upper limit on the local merger rate for subsolar BNSs, constraining it to be <6.4 × 10 ^4 Gpc ^−3 yr ^−1 for a chirp mass of 0.2 M _⊙ and <2.2 × 10 ^3 Gpc ^−3 yr ^−1 for 0.7 M _⊙ . With future upgrades to detector sensitivity, development of next-generation detectors, and ongoing improvements in search pipelines, constraints on the minimum mass of neutron stars will improve, providing the potential to constrain the nuclear equation of state, reveal new insights into neutron star formation channels, and potentially identify new classes of stars.https://doi.org/10.3847/1538-4357/adc9a5Gravitational wavesGravitational wave sourcesNeutron starsGravitational wave astronomy
spellingShingle Keisi Kacanja
Alexander H. Nitz
A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
The Astrophysical Journal
Gravitational waves
Gravitational wave sources
Neutron stars
Gravitational wave astronomy
title A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
title_full A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
title_fullStr A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
title_full_unstemmed A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
title_short A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo
title_sort search for low mass neutron stars in the third observing run of advanced ligo and virgo
topic Gravitational waves
Gravitational wave sources
Neutron stars
Gravitational wave astronomy
url https://doi.org/10.3847/1538-4357/adc9a5
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