Dark Matter

Dark Matter Could Be Annihilating Inside White Dwarfs

As the search for dark matter particles continues to yield nothing, astronomers continue to look at ways these elusive particles might be found. One general method is to look for evidence of dark matter particle decay. Although dark matter doesn’t interact strongly with regular matter, some dark matter models predict that dark matter particles can interact with each other, causing them to decay into regular particles. There have been several searches for this effect, but there’s no clear evidence yet. But a new study suggests looking at white dwarfs could be a good approach.

White dwarfs are the dense remnants of dead stars. They have nearly a Sun’s worth of mass compressed into a sphere the size of Earth. White dwarfs are so dense it is the pressure of electrons that keeps them from collapsing. As the authors of this new study point out, white dwarfs have a perfect balance of being dense but not overly tiny like neutron stars. They are also very common throughout the Milky Way, giving astronomers plenty of options to study them.

For this reason, the authors argue that white dwarfs are perfect sources for dark matter decay. The high density of white dwarfs would tend to attract dark matter particle interactions, and the high surface gravity of white dwarfs would tend to capture dark matter particles over time. The particle decay from dark matter would tend to produce an excess of both heat and gamma rays, and since white dwarf physics is fairly well understood astronomers should be able to distinguish between normal and dark-matter enriched white dwarfs.

Observational constraints on dark matter decay. Credit: Acevedo, et al

As an example of this, the team considered a simple white dwarf model comprised entirely of carbon-12. They then considered dark matter capture for three particle models, with light, intermediate, and heavy masses. They then calculated the interaction cross-sections between dark matter particles and the nucleons of regular matter in the white dwarf. From this, they determined the observational constraints of dark matter based on current observations.

There isn’t any evidence of dark matter decay thus far, but the authors suggest that a direct study of individual white dwarf stars could reveal dark matter. White dwarfs near the center of the Milky Way, or those in nearby globular clusters could be particularly good candidates.

So nothing yet, but as astronomers continue to search for dark matter, checking out some white dwarfs looking for excess gamma-rays could be a good option.

Reference: Acevedo, Javier F., Rebecca K. Leane, and Lillian Santos-Olmsted. “Milky Way White Dwarfs as Sub-GeV to Multi-TeV Dark Matter Detectors.” arXiv preprint arXiv:2309.10843 (2023).

Brian Koberlein

Brian Koberlein is an astrophysicist and science writer with the National Radio Astronomy Observatory. He writes about astronomy and astrophysics on his blog. You can follow him on YouTube, and on Twitter @BrianKoberlein.

Recent Posts

Hubble and Webb are the Dream Team. Don't Break Them Up

Many people think of the James Webb Space Telescope as a sort of Hubble 2.…

2 hours ago

Scientists Have Figured out why Martian Soil is so Crusty

On November 26th, 2018, NASA's Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight)…

10 hours ago

Another Way to Extract Energy From Black Holes?

Black holes are incredible powerhouses, but they might generate even more energy thanks to an…

16 hours ago

Plastic Waste on our Beaches Now Visible from Space, Says New Study

According to the United Nations, the world produces about 430 million metric tons (267 U.S.…

1 day ago

Future Space Telescopes Could be Made From Thin Membranes, Unrolled in Space to Enormous Size

As we saw with JWST, it's difficult and expensive to launch large telescope apertures, relying…

2 days ago

Voyager 1 is Forced to Rely on its Low Power Radio

Voyager 1 was launched waaaaaay back in 1977. I would have been 4 years old…

2 days ago