Lhaaso Detects TeV-PeV Diffuse Rays, Constraining Dark Matter Signatures in the GeV Mass Range

The search for dark matter receives a powerful boost from new observations of high-energy rays emanating from our galaxy, as detailed in research led by Celine Boehm from The University of Edinburgh, Ranjan Laha from the Indian Institute of Science, and Tarak Nath Maity from The University of Sydney. The team analysed data from the LHAASO ground-based observatory, focusing on these rays in the TeV-PeV range, to investigate the possibility of heavy dark matter particles decaying or annihilating. This analysis establishes the strongest constraints to date on the properties of such dark matter candidates, significantly narrowing the range of possibilities for their mass and interaction strength, and demonstrating LHAASO’s potential to unlock the secrets of this elusive substance. By carefully modelling the expected signals from both within our galaxy and from distant sources, the researchers reveal how future observations can further refine our understanding of dark matter’s true nature.

Recent observations of diffuse γ-rays from the Galactic plane in the TeV and PeV ranges are now being used to investigate the possibility of heavy decaying and annihilating dark matter particles, with masses between 10⁵ and 10⁹ GeV. This research analyses this data, offering a complementary approach to experiments searching for dark matter through particle collisions or direct interactions.

Indirect Dark Matter Detection via Secondary Particles

The search for dark matter increasingly focuses on indirect detection methods, looking for signals produced when dark matter particles interact and annihilate or decay. These interactions are expected to create secondary particles, such as gamma rays, neutrinos, and cosmic rays, which telescopes can detect. A significant amount of research has concentrated on Weakly Interacting Massive Particles (WIMPs), historically the leading dark matter candidate, and setting limits on their potential interaction rates. However, there is growing interest in heavier dark matter candidates, driven by the lack of WIMP detections and new theoretical models.

Gamma-ray astronomy plays a crucial role in this search, with telescopes scanning the sky for excess gamma-ray emission from regions where dark matter is expected to concentrate. Neutrino astronomy is also becoming increasingly important, particularly for heavier dark matter candidates. Cosmic ray studies seek anomalies in the cosmic ray spectrum that could be attributed to dark matter interactions. Accurate modelling of how cosmic rays and gamma rays propagate through the galaxy is essential for interpreting these signals and distinguishing them from astrophysical backgrounds. Theoretical work continues to refine models and set limits on dark matter properties.

Recent years have seen a broadening of the search beyond the traditional WIMP mass range, with increased attention given to heavier candidates and alternative models like axions and sterile neutrinos. Combining data from multiple messengers, gamma rays, neutrinos, and cosmic rays, is becoming increasingly important for improving the sensitivity of dark matter searches. The Large High Altitude Air Shower Observatory (LHAASO) is a new generation observatory providing unprecedented sensitivity to high-energy cosmic rays and gamma rays, and is playing an increasingly important role in these investigations. Researchers are also exploring concepts like homeopathic dark matter and heavy thermal dark matter. This body of research demonstrates a vibrant and evolving field, moving beyond the initial focus on WIMPs and embracing a wider range of theoretical models and observational techniques. The combination of multi-messenger astronomy, new telescopes like LHAASO, and innovative theoretical ideas is paving the way for potential breakthroughs in the years to come.

Dark Matter Search with Cosmic Ray Data

The Large High Altitude Air Shower Observatory (LHAASO) is providing groundbreaking insights into high-energy rays and cosmic rays. Recent observations of diffuse γ-rays from the Galactic plane in the TeV-PeV range are now being used to search for evidence of dark matter. Scientists have, for the first time, analysed this data to constrain the properties of heavy decaying and annihilating dark matter particles, focusing on a mass range from 10⁵ to 10¹¹ GeV. This research offers a complementary approach to collider and direct detection experiments, which face limitations in probing such heavy particles.

The team meticulously modelled the expected flux of photons from both Galactic and extragalactic dark matter, accounting for attenuation caused by pair production. For the Galactic contribution, calculations incorporated both promptly produced photons and secondary photons generated through inverse Compton scattering of electrons and positrons, carefully tracing their propagation within the galaxy. Extragalactic signals were similarly modelled, including contributions from prompt photons, inverse Compton scattering, and cascade effects. By combining these detailed calculations, researchers derived robust constraints on the parameter space governing dark matter properties.

The results demonstrate that LHAASO currently provides the strongest constraints to date on two-body Standard Model final states for dark matter annihilation and decay. This achievement underscores LHAASO’s unique capability to probe the nature of heavy dark matter, opening new avenues for discovery in this elusive field. The study highlights the power of indirect detection methods, leveraging high-energy photons as messengers from dark matter interactions to reveal previously inaccessible mass scales and interaction strengths. Future observations with LHAASO promise even greater sensitivity, potentially unveiling the fundamental properties of dark matter and resolving one of the most significant mysteries in modern science.

LHAASO Constrains Heavy Dark Matter Properties

This research presents new constraints on the properties of heavy dark matter candidates, utilising data from the Large High Altitude Air Shower Observatory (LHAASO). By analysing high-energy gamma rays originating from the Galactic plane, the team searched for signals indicative of dark matter annihilation or decay into standard model particles. The study carefully models the expected gamma ray flux from both within our galaxy and from sources beyond it, accounting for various processes that can produce these signals, including direct emission and secondary emissions from interactions within the galaxy. The results demonstrate that LHAASO provides the strongest current limits on the properties of dark matter particles in the mass range of 10⁵ to 10¹¹ GeV. These findings highlight the observatory’s capability to probe previously inaccessible regions of the dark matter parameter space, complementing existing searches conducted by collider and direct detection experiments. Future research could refine these models and explore a wider range of dark matter decay and annihilation channels to further constrain the nature of this elusive substance.