Caltech study hints at black holes born from failed supernovae

Phys.org reported that a Caltech-led study published in Physical Review D in 2026 found hints in LIGO–Virgo–KAGRA gravitational-wave data of a black hole population that may have formed through failed supernovae, though the researchers found no direct evidence for such events.

The team examined 257 black hole mergers from the LIGO–Virgo–KAGRA network recorded during the previous decade to assess the failed-supernova hypothesis. The data revealed a strong concentration of black holes at 10 solar masses, comprising three-quarters of the 257-merger sample, and a distinct shortage in the 12- to 16-solar-mass range. Researchers examined the mass distribution of mergers detected over the past decade by the network, and the concentration and the gap together suggest the 10-solar-mass objects may form a separate group with a shared history.

Spin measurements showed the 10-solar-mass black holes occupy a tighter spin range than the full black hole sample. Spin rates carry information about formation history. The tighter spin distribution, combined with the mass peak and gap, supports a distinct formation channel such as the quiet implosion of massive stars.

Previous work found merging black holes often sit near 10 solar masses, and theorists suggested this large group may represent failed supernovae, meaning one or both members of a merging pair could originate from a star that imploded instead of exploding. The failed-supernova idea attributes the abundance of 10-solar-mass black holes to quiet stellar collapse instead of explosive death. The Caltech-led team tested whether this concept fits the gravitational-wave observations by comparing prior detections with theoretical predictions rather than watching a failed collapse happen.

Katerina Chatziioannou, a Caltech physics professor and William H. Hurt Scholar, led the research. She said most merging black holes have a mass around 10 solar masses and may be a distinct subpopulation that did not go supernova, linking the observations to stellar physics. Chatziioannou described the results as a link between observations and the astrophysics researchers are trying to extract, a statement reflecting the study’s interpretation of the common 10-solar-mass peak.

Isaac Legred, a University of Illinois Urbana-Champaign postdoctoral researcher who earned his Ph.D. in 2025 and performed the work at Caltech, is the study’s lead author. Jacob Golomb, who earned his Ph.D. in 2025, was a former Chatziioannou lab member and is now at Asari AI; he co-authored the study. Physical Review D published the research, and the team spans Caltech and institutions where two authors now work.

A failed supernova occurs when a massive star collapses quietly instead of detonating. The star vanishes without a blast, leaving a dark patch of sky, which makes it challenging to study such events from historical optical records, Legred said. He contrasted optical searches for failed supernovae with the gravitational-wave approach, noting that the stars leave little observable trace and are hard to study from historical records.

Legred said current gravitational-wave observations match the expected signature of most binary black holes arising from an unusual failed-supernova channel, though further work is required. He said the chance to learn more about how black holes form is exciting because they arise in exceptionally extreme cosmic settings, and he described the results as showing consistency rather than proof.

He said 10-solar-mass black holes merge all the time while 14-solar-mass black holes are rare, and he asked why the 14-solar-mass objects are so scarce compared with the common 10-solar-mass mergers. He argued the mass gap indicates a special cocktail of internal physics behind the abundance of 10-solar-mass black holes, and he said the gap points to a distinct formation path for the prevalent mass.

LIGO operates detectors in Louisiana and Washington and recorded the initial direct observation of gravitational waves in 2015 from merging black holes. LIGO began direct gravitational-wave astronomy with its 2015 observation of colliding black holes, and Virgo in Italy and KAGRA in Japan joined LIGO to form one observing network. The combined observatories have recorded over 300 black hole collisions, and the addition of Virgo and KAGRA expanded the network behind the merger catalog used in the study.

Physical Review D published the Isaac Legred et al. study in 2026 under the title Low-mass failed supernovae and the 10 M ⊙ peak, followed by the merging black hole mass distribution, with DOI 10.1103/mnzq-w1b5 and arXiv identifier 2604.01420. The preprint is available on arXiv, and the publication credits Isaac Legred and co-authors. Phys.org’s report emphasized that the research rests on the idea that some massive stars collapse quietly rather than detonating, and that the team found hints of a distinct black hole population rather than direct evidence of failed-supernova births.