{"work":{"id":"656cc9de-36c5-47da-a727-23d549d519d9","openalex_id":null,"doi":null,"arxiv_id":"2106.15163","raw_key":null,"title":"Observation of gravitational waves from two neutron star-black hole coalescences","authors":null,"authors_text":"R","year":2021,"venue":"astro-ph.HE","abstract":"We report the observation of gravitational waves from two compact binary coalescences in LIGO's and Virgo's third observing run with properties consistent with neutron star-black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo, and the second by all three LIGO-Virgo detectors. The source of GW200105 has component masses $8.9^{+1.2}_{-1.5}\\,M_\\odot$ and $1.9^{+0.3}_{-0.2}\\,M_\\odot$, whereas the source of GW200115 has component masses $5.7^{+1.8}_{-2.1}\\,M_\\odot$ and $1.5^{+0.7}_{-0.3}\\,M_\\odot$ (all measurements quoted at the 90% credible level). The probability that the secondary's mass is below the maximal mass of a neutron star is 89%-96% and 87%-98%, respectively, for GW200105 and GW200115, with the ranges arising from different astrophysical assumptions. The source luminosity distances are $280^{+110}_{-110}$ Mpc and $300^{+150}_{-100}$ Mpc, respectively. The magnitude of the primary spin of GW200105 is less than 0.23 at the 90% credible level, and its orientation is unconstrained. For GW200115, the primary spin has a negative spin projection onto the orbital angular momentum at 88% probability. We are unable to constrain spin or tidal deformation of the secondary component for either event. We infer a NSBH merger rate density of $45^{+75}_{-33}\\,\\mathrm{Gpc}^{-3} \\mathrm{yr}^{-1}$ when assuming GW200105 and GW200115 are representative of the NSBH population, or $130^{+112}_{-69}\\,\\mathrm{Gpc}^{-3} \\mathrm{yr}^{-1}$ under the assumption of a broader distribution of component masses.","external_url":"https://arxiv.org/abs/2106.15163","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-07-10T13:17:05.723670+00:00","pith_arxiv_id":"2106.15163","created_at":"2026-05-12T02:40:30.609207+00:00","updated_at":"2026-07-10T13:17:05.723670+00:00","title_quality_ok":true,"display_title":"Abbottet al.(LIGO Scientific, KAGRA, VIRGO), As- trophys","render_title":"Abbottet al.(LIGO Scientific, KAGRA, VIRGO), As- trophys"},"hub":{"state":{"work_id":"656cc9de-36c5-47da-a727-23d549d519d9","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":23,"external_cited_by_count":null,"distinct_field_count":5,"first_pith_cited_at":"2021-08-02T17:09:29+00:00","last_pith_cited_at":"2026-07-09T03:55:45+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-08-22T17:49:32.677928+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":5}],"polarity_counts":[{"context_polarity":"background","n":5}],"runs":{},"summary":{},"graph":{},"authors":[]}}