Sub-Solar Black Holes: Formation and Impact on Stellar Objects

In their April 2025 paper titled Accretion inside astrophysical objects: Effects of rotation and viscosity, researchers H. A. Adarsha, Chandrachur Chakraborty, and Sudip Bhattacharyya investigate the formation of tiny black holes within stellar objects through particle capture and thermalization. Their study reveals that accretion can stall in white dwarfs but not in neutron stars, highlighting the complex dynamics influenced by rotation and viscosity.

The study explores how sub-solar mass black holes, which cannot form through stellar evolution, might emerge via exotic mechanisms such as particle capture leading to endoparasitic black holes (EBHs). These EBHs can accrete matter from their hosts, potentially transforming them into black holes of similar or lesser mass. The research examines accretion dynamics in white dwarfs and neutron stars, considering effects like rotation and viscosity but excluding others such as pressure and magnetic fields. It finds that accretion may stall in white dwarfs due to host properties, creating polar region openings dependent on the host’s mass and spin, while neutron stars remain unaffected by this stalling mechanism.

In the vast expanse of the cosmos, dark matter remains an enigmatic presence, comprising approximately 27% of the universe’s mass-energy. Its elusive nature has puzzled scientists for decades, but a novel approach using neutron stars and gravitational waves offers fresh hope in unraveling this mystery.

Dark matter does not emit or absorb light, making it invisible to traditional telescopes. Its presence is inferred through gravitational effects on visible matter, such as stars and galaxies. Scientists have long sought the particles that make up dark matter, with axions and ultralight bosons being prominent candidates. These hypothetical particles, with extremely low mass, could form a Bose-Einstein condensate (BEC), exhibiting quantum properties on macroscopic scales.

Neutron stars, remnants of massive stars after supernova explosions, provide unique environments for studying extreme physics. Their intense gravitational fields and rapid rotation make them ideal laboratories for testing dark matter theories. If axions or ultralight bosons exist around neutron stars, they could accumulate due to the star’s gravity, potentially forming a BEC. This condensate might interact with the neutron star’s spin, causing measurable effects detectable through advanced observations.

Gravitational wave detectors like LIGO and Virgo have revolutionized astrophysics by observing cosmic events such as neutron star mergers. These detectors measure spacetime ripples caused by massive objects accelerating at extreme speeds. In dark matter research, gravitational waves offer a unique opportunity to study axions or ultralight bosons’ effects on neutron stars. If these particles form a BEC around a neutron star, they could cause detectable gravitational wave distortions.

This innovative approach highlights the collaboration between astrophysics, particle physics, and gravitational wave astronomy. By combining insights from these fields, scientists can explore dark matter’s properties in unprecedented ways. This interdisciplinary synergy may soon provide the key to unlocking the mystery of dark matter, offering new perspectives on the universe’s composition and behavior.

In conclusion, neutron stars and gravitational waves present a promising avenue for dark matter detection. As research progresses, this approach could reveal the elusive nature of dark matter, shedding light on one of the cosmos’s greatest mysteries.