A new study argues that black holes left over from the Big Bang may have triggered a share of Type Ia supernovae — and that their chemical fingerprints are written into the stars of the Milky Way.

Featured image credit: Adam Makarenko/W. M. Keck Observatory

Type Ia supernovae are among the most important explosions in astronomy. They are bright enough to be seen across billions of light-years and uniform enough to serve as cosmic yardsticks, the standard candles astronomers used to discover that the expansion of the universe is accelerating. They are also chemical factories, forging much of the iron and related elements that end up in later generations of stars and planets.

Yet the question of what sets them off has never been fully settled. Now an international team of researchers proposes that at least some of these explosions may have been triggered by one of the most elusive objects in physics: primordial black holes. In a study published June 20 in The Astrophysical Journal, the team reports that such black hole-triggered supernovae could explain several features of known supernova remnants, nearby supernovae, and the chemical makeup of stars in the Milky Way.^1,2

Relics of the first moments

Primordial black holes, or PBHs, are hypothetical black holes thought to have formed in the earliest moments of the universe, during the period of rapid expansion known as inflation, when fluctuations in the density of matter could have collapsed directly into black holes. Unlike black holes born from dying stars, PBHs could in principle come in a wide range of masses, including very small ones. They are also one of the candidates proposed to explain dark matter, the invisible substance that makes up most of the matter in the universe by mass.²

If PBHs exist in large numbers, some of them would occasionally pass through stars. Earlier theoretical work suggested that when one of these black holes passes through a white dwarf — the dense, Earth-sized remnant left behind when a low-mass star dies — the tidal effects of its gravity could ignite the white dwarf and make it explode as a Type Ia supernova.²

Testing the idea against the sky

The team was led by Shing-Chi Leung, an assistant professor at SUNY Polytechnic Institute and visiting associate scientist at the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), and included Kavli IPMU visiting senior scientist Ken’ichi Nomoto and senior fellow Alexander Kusenko. They examined the dynamical, optical, and chemical characteristics of supernovae produced through this proposed PBH-triggered channel.²

In an earlier paper published in 2025, the group showed that PBH-triggered explosions could produce supernovae that closely resemble standard Type Ia models.² That was an important first step: if the black hole-triggered explosions looked nothing like real supernovae, the idea could be dismissed quickly. The new study, the second in the series, goes further by comparing the model’s predictions with actual observations.

The researchers compared their simulations with the remnants of three historical supernovae — Tycho, Kepler, and 3C 397 — along with nearby supernovae such as SN 2011fe and SN 2012cg, and with the chemical abundances measured in Milky Way stars. By examining radioactive isotopes including nickel-56 and nickel-57, and stable elements such as manganese and nickel, they were able to estimate the masses and metallicities of the stars that exploded. Metallicity, the abundance of elements heavier than hydrogen and helium when a star forms, acts as a rough clock for when in cosmic history a star was born.²

A chemical signature

The most striking result came from modeling how the Milky Way’s chemistry has built up over time. When the team incorporated the PBH-triggered channel into a model of galactic chemical enrichment, they found that a non-zero fraction of PBH-triggered Type Ia supernovae was necessary to reproduce the chemical abundance trend seen in the galaxy’s stars.² In other words, the pattern of elements in our own galaxy is easier to explain if some of the supernovae that seeded it were set off by primordial black holes.

That is not proof that PBHs exist. Models of galactic chemistry involve many assumptions, and other explanations for the observed trends may yet emerge. But it does offer something rare in the study of hypothetical objects: a potentially testable trace in data astronomers already have.

“Our work suggests that some supernova that we observe in the sky could be a result of the PBHs,” Leung said. “Therefore, even though we cannot directly observe these evasive entities, they leave many interesting clues in nature for us to probe their properties.”²

Why it matters

If the idea holds up, it would matter for at least two big questions. First, it would offer a new, indirect way to search for primordial black holes and to constrain their abundance and masses, which bears directly on whether they could account for some or all of dark matter. Second, it would add a new pathway to the long-debated question of how Type Ia supernovae are triggered — a question with consequences for how reliably they can be used to measure cosmic distances.

The team says its next step is to examine how PBH-triggered explosions might change the population of conventional supernovae and the overall rates of these transient events.² As large sky surveys catalog supernovae by the thousands, those rates may become one of the sharper tests of whether relics from the universe’s first instants are still setting off fireworks today.

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Notes

1. Primordial Black Hole Triggered Type Ia Supernovae II: Comparison with Supernova Remnants and Galactic Chemical Evolution. (2026). The Astrophysical Journal. https://doi.org/10.3847/1538-4357/ae6db7
2. Kavli Institute for the Physics and Mathematics of the Universe. (2026, July 22). Researchers uncover signatures of primordial black holes when triggering Type Ia supernovae [Press release]. EurekAlert! https://www.eurekalert.org/news-releases/1137129