• Two independent teams searched for axions in starburst galaxies M82 and M87 using NuSTAR x-ray data.
• The teams targeted different axion mass ranges and production mechanisms: light axions converting to x-ray photons and heavy axions decaying into photons.
• No axion signal was detected, but the research set new limits on axion properties and motivates further searches in other galaxies and with different detection methods.

Two research teams have independently investigated the potential of starburst galaxies, specifically M82 and M87, as sources of axions, hypothetical particles that are strong candidates for dark matter. These studies utilized x-ray data from NASA's NuSTAR telescope to search for signatures of axion production and decay. While no axion signal was definitively detected, the analyses have provided valuable constraints on the properties of these elusive particles, paving the way for future searches.

• What: Two teams searched for axions by analyzing x-ray data from starburst galaxies, looking for spectral distortions that would indicate axion production or decay.
• Who: Benjamin Safdi and Orion Ning (UC Berkeley), Edoardo Vitagliano et al. (University of Padua), Ciaran O’Hare (University of Sydney), Samuel Witte (University of Oxford).
• When: The research was published in Physical Review Letters on May 1, 2025, based on NuSTAR data collected since 2012.
• Where: The search focused on the starburst galaxies M82 (Cigar Galaxy) and M87.

The research represents a significant step in the ongoing search for axion dark matter. By targeting entire galaxies, the teams were able to leverage the potential of these massive systems as axion factories. The use of x-ray data from NuSTAR provided a unique window into the axion production and decay processes. While no definitive signal was detected, the constraints placed on axion properties will help guide future searches. The article highlights the complexities of modeling axion production in galaxies and the uncertainties associated with astronomical observations, suggesting that further research is needed to refine these models.

Axions are some of the best motivated candidates at the moment for physics beyond the standard model.

This means that you have to smash a lot of particles against each other so that you have the chance of observing something.

We think of stars as axion factories. The Sun is the closest and thus the simplest factory to deal with, but there are maybe better sources out there.

We’ve taken this factory analogy to the extreme.

If these particles exist, they would outshine what you already observe in x rays.

We are gaining new insights into axions by looking for them in data collected by astronomers who are interested in these galaxies for entirely different reasons.

The search for axions in starburst galaxies using NuSTAR x-ray data has yielded valuable constraints on their properties, even without a definitive detection. This research underscores the potential of astrophysical observations to probe fundamental physics beyond the Standard Model. Future studies will likely focus on exploring other galaxies, refining axion production models, and employing complementary detection techniques to further narrow down the axion parameter space.