The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 ¹/₂ years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Using the latest AMS-02 cosmic-ray antiproton flux data, we search for a potential dark matter annihilation signal. The background parameters about the propagation, source injection, and solar modulation are not assumed a priori but based on the results inferred from the recent $\mathrm{B}/\mathrm{C}$ ratio and proton data measurements instead. The possible dark matter signal is incorporated into the model self-consistently under a Bayesian framework. Compared with the astrophysical background-only hypothesis, we find that a dark matter signal is favored. The rest mass of the dark matter particles is $\sim 20–80\mathrm{GeV}$, and the velocity-averaged hadronic annihilation cross section is about $(0.2–5)\times {10}^{-26}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$, in agreement with that needed to account for the Galactic center GeV excess and/or the weak GeV emission from dwarf spheroidal galaxies Reticulum 2 and Tucana III. Tight constraints on the dark matter annihilation models are also set in a wide mass region.

High-energy photons from the Crab Nebula: The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location makes the nebula the brightest gamma-ray source in the sky. The LHAASO Collaboration report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering. Science , abg5137, this issue p. 425

The diffuse Galactic $\gamma$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse $\gamma$ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner ($15°<l<125°$, $|b|<5°$) and outer ($125°<l<235°$, $|b|<5°$) Galactic plane are detected with $29.1\sigma$ and $12.7\sigma$ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain ($E>10\mathrm{TeV}$). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of $-2.99\pm 0.04$, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of $\sim 3$ than the prediction. A similar spectrum with an index of $-2.99\pm 0.07$ is found in the outer Galaxy region, and the absolute flux for $10\lesssim E\lesssim 60\mathrm{TeV}$ is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

With high spatial resolution, polarimetric imaging of a supermassive black hole, like $\mathrm{M}{87}^{\star }$ or Sgr ${\mathrm{A}}^{\star }$, by the Event Horizon Telescope can be used to probe the existence of ultralight bosonic particles, such as axions. Such particles can accumulate around a rotating black hole through the superradiance mechanism, forming an axion cloud. When linearly polarized photons are emitted from an accretion disk near the horizon, their position angles oscillate due to the birefringent effect when traveling through the axion background. In particular, the observations of supermassive black holes $\mathrm{M}{87}^{\star }$ (Sgr ${\mathrm{A}}^{\star }$) can probe the dimensionless axion-photon coupling $c=2\pi g_{a\gamma }{f}_a$ for axions with mass around $O({10}^{-20})\mathrm{eV}$ [$O({10}^{-17})\mathrm{eV}$] and decay constant $f_a<O({10}^{16})\mathrm{GeV}$, which is complimentary to other axion measurements.