Primordial Black Holes as Dark Matter and Triggers of Type Ia Supernovae ✦
Primordial black holes with asteroid-like masses (4×10⁻¹⁷–4×10⁻¹² M⊙) are dark matter candidates. Accreting onto white dwarfs, they can ignite Type Ia supernovae. We develop explosion scenarios for a range of metallicities (heavy element content). These scenarios successfully reproduce recent observations of light curves and supernova remnants. The impact of these events on galactic chemical evolution is examined: models incorporating this new element source explain observed trends and allow us to estimate the contribution of the PBH-supernova channel relative to the canonical one (thermonuclear explosions in binary systems). We conclude that PBH-induced supernovae may have dominated in the early Universe. The influence of explosion parameters on chemical trends is also investigated.
Context
The nature of dark matter remains one of the greatest puzzles in modern physics. Among the candidates are primordial black holes (PBHs), which could have formed in the early Universe before stars appeared. If their masses fall into the asteroid range (roughly 10^{-17}–10^{-12} solar masses), they could make up all dark matter. Such objects are nearly impossible to detect by conventional means, but their gravitational pull on compact stars, like white dwarfs, can trigger a thermonuclear explosion — a Type Ia supernova. Unlike the standard binary scenario, this mechanism lets a lone white dwarf blow up, making it especially important for early galactic evolution, when dark matter density was much higher.
Methods
Researchers used multidimensional hydrodynamic simulations, igniting a white dwarf at a specific point corresponding to a passing PBH. They applied a model of turbulent deflagration transitioning into detonation. Post-process nucleosynthesis with a network of 495 isotopes (from hydrogen to technetium) allowed calculation of chemical element yields as a function of initial metallicity, parameterized by the fraction of carbon and oxygen, as well as neon-22 content. The resulting models were integrated into a galactic chemical evolution code, which accounted for contributions from massive stars, ordinary Type Ia supernovae, and the new PBH channel. Observational comparisons used data on supernova remnants (X-ray spectroscopy) and stellar element abundances from surveys like APOGEE and SAGA.
Results
The models showed that as metallicity rises from 0 to 0.1 solar, PBH-ignited Type Ia supernovae boost production of neutron-rich isotopes like ^{55}Mn and ^{58}Ni, while alpha-chain elements (e.g., carbon, oxygen) change little. The yield of ^{56}Ni varies from 0.2 to 1.1 solar masses, spanning the full diversity of observed Type Ia supernovae. Comparisons with supernova remnants (Kepler, Tycho, 3C 397) and light curves (SN 2011fe, SN 2014J) showed that many can be explained by PBH-triggered explosions of white dwarfs of different masses and metallicities. Incorporating these models into galactic chemical evolution gave the best agreement with observed [Mn/Fe] and [Ni/Fe] trends for a non-zero fraction of PBH supernovae (DPBH ~0.01–0.02) and a channel shut-off time around 9 billion years. Moreover, the models suggest that PBH explosions could introduce systematics into the use of Type Ia supernovae as standard candles for measuring cosmic expansion, which is critical for refining the properties of dark energy.
Implications
The results show for the first time that dark matter in the form of primordial black holes can not only make up the Universe's hidden mass but also actively influence stellar evolution and nucleosynthesis. This opens a new astrophysical way to test the nature of dark matter: detailed measurements of chemical abundances in stars and supernova remnants can constrain or even confirm the existence of PBHs. Moreover, the link between PBH channel parameters and elemental evolution in the Galaxy provides an independent tool to study the early history of star formation.
Future development
Future work will account for explosion delay distributions in binary systems and more detailed modeling of dark matter profiles in galaxies. New data from X-ray telescopes (e.g., XRISM) and infrared surveys (high-resolution spectroscopy) will enable more precise measurements of rare isotopes in supernova remnants and direct comparisons with predictions. Also promising is the study of PBH-supernova contributions to the chemical enrichment of the intergalactic medium and galaxy clusters.
Impact
The proposed mechanism touches several fields at once: particle physics and dark matter, compact-object astrophysics, and cosmology. In particular, it could reshape the interpretation of dark energy, since Type Ia supernovae serve as standard candles for measuring cosmic expansion; if some of them have a non-standard origin, this may slightly tweak cosmological parameters.
Next steps
Next steps include developing more realistic models that account for mass accretion onto the white dwarf before the explosion and the evolution of dark matter density over time. Additionally, joint fitting of supernova rates and chemical evolution is needed to simultaneously constrain model parameters.
Key open problems
This work ties directly into the unsolved problem of the nature of dark matter and the search for its astrophysical signatures beyond gravity. It also tackles the puzzle of Type Ia supernova mechanisms — why they are so diverse and whether they can explode without a companion star. Finally, chemical evolution modeling links the physics of black holes to the history of the early Universe and the buildup of chemical elements in galaxies.
🎯 If an asteroid-mass primordial black hole zips through a white dwarf, it dumps enough heat to spark a thermonuclear blast, while the black hole itself emerges unscathed and continues its journey across the galaxy.
Key numbers
- PBH mass: 4×10^{-17} – 4×10^{-12} M⊙
- PBH supernova fraction: 0.01–0.02 of all white dwarfs
- PBH channel shut-off time: about 9 billion years
- Nickel-56 yield: 0.2–1.1 M⊙
- Model metallicity: 0–0.1 solar