• HAWC Collaboration finds evidence that TeV gamma-ray halos may be ubiquitous around middle-aged pulsars.
• The uniformity of the halos suggests a previously unknown particle-transport phenomenon inherent to middle-aged pulsars.
• TeV observations could be used to discover pulsars that are invisible in other wave bands.

The High-Altitude Water Cherenkov (HAWC) Observatory has discovered that tera-electron-volt (TeV) gamma-ray halos may be a common feature around middle-aged pulsars. This discovery stems from a survey of such pulsars, building upon initial observations in 2017 that revealed halos around two nearby pulsars. The finding suggests that these halos are not anomalous but rather indicative of a particle-transport phenomenon associated with middle-aged pulsars, offering a new method for pulsar detection and insights into particle diffusion in interstellar space.

• What: Discovery of potentially ubiquitous TeV gamma-ray halos around middle-aged pulsars.
• Who: HAWC Collaboration, A. Albert et al., A. U. Abeysekara et al.
• When: Initial discovery of halos around two pulsars in 2017, followed by a survey concluding in 2025 (publication date of Phys. Rev. Lett. article).
• Where: Observations made by the High-Altitude Water Cherenkov (HAWC) Observatory.

The HAWC Collaboration's finding that TeV gamma-ray halos may be ubiquitous around middle-aged pulsars is significant for several reasons. First, it suggests a new method for identifying pulsars, especially those with orientations that make them difficult to detect using traditional methods. Second, the uniformity of the halos points to a common particle-transport phenomenon inherent to middle-aged pulsars, challenging existing models of particle diffusion in the interstellar medium. This could lead to a better understanding of the processes that govern the behavior of relativistic particles in these environments. The research builds upon previous work and provides a broader context for understanding the behavior of pulsars and their interaction with the surrounding environment.

The HAWC Collaboration's research provides compelling evidence that TeV gamma-ray halos are likely a common feature around middle-aged pulsars. This discovery not only opens new avenues for pulsar detection but also presents a challenge to current understanding of particle transport in the interstellar medium. Further research is needed to fully understand the nature of this phenomenon and its implications for astrophysics.