Context. Pulsars and their environments represent a major class of Galactic γ-ray sources. Their complex evolution, shaped by the interactions of the pulsar outflow with both the supernova remnant (SNR) and the surrounding interstellar medium (ISM), produces diverse morphological and spectral characteristics observable from radio to PeV energies. Aims. This work aims to collect and homogenise data from all major operating TeV observatories, presenting the first comprehensive catalogue of TeV γ-ray properties of pulsar environments, and facilitating systematic studies of the evolution of pulsar wind nebulae and pulsar halos. Methods. The catalogue was created from information regarding all γ-ray sources that have been classified as pulsar-associated sources in published results from H.E.S.S., MAGIC, VERITAS, HAWC, and LHAASO. For each source, the observed γ-ray properties were cross-matched with pulsar properties from the ATNF catalogue and Fermi-LAT pulsar catalogue. This information was then used to predict the surface brightness for powerful pulsars around which no nebula has been detected yet. Results. The final catalogue comprises all currently known TeV sources associated with pulsars, as seen by different instruments, spanning all evolutionary stages. The sample consists of 128 γ-ray sources, connected to 66 different pulsars. It reflects that the TeV-detected population is dominated by young and energetic pulsars located near the Galactic plane, but includes a growing number of middle-aged systems detected as extended halos. Only a weak correlation is found between TeV luminosity and pulsar characteristic age, indicating that TeV evolution is driven by environmental and transport effects rather than by spin-down age alone. Additionally, five pulsars that should host a PWN detectable by CTAO are identified as prime targets for future observation to improve our under-standing of properties inhibiting the formation of a TeV nebula. Conclusions. This publicly available catalogue provides a uniform foundation for future population studies and for constraining models of particle transport and energy losses in pulsar environments.

Upcoming near-infrared facilities (e.g., JWST/NIRCam, ELT/MICADO) will dramatically increase the detectability of Galactic Center Cepheids despite extreme extinction at optical wavelengths. In this work, we study the impact of dark matter (DM) annihilation on Cepheid stars in the inner parsec of the Milky Way. We show that at captured densities 𝜌∼10⁵  GeV cm⁻³, blue loop evolution can be suppressed, preventing the formation of low-mass (3–6⁢𝑀_⊙) short-period (1–6 days) Cepheids. For even slightly higher DM densities, Cepheids are suppressed across their entire mass range. A dearth of such variables could provide indirect evidence for DM heating. Notably, this effect occurs at lower DM densities than required to impact main-sequence stars. Future surveys will thus offer a novel, complementary probe of DM properties in galactic nuclei.

The High-Energy Stereoscopic System (H.E.S.S.) telescope has recently detected the total electron-plus-positron (𝑒⁺⁢𝑒⁻) flux up to 40 TeV, finding it to be a featureless and steeply falling power law above 1 TeV. This result is in stark tension with standard one-zone models of pulsar 𝑒⁺⁢𝑒⁻ injection and diffusion, which predict a hard-spectrum signal above ∼10  TeV. We model the local pulsar population, and find 21 sources that would each individually overproduce the H.E.S.S. 𝑒⁺⁢𝑒⁻ flux in a one-zone diffusion model. We conclude that every energetic pulsar younger than ∼500  kyr must be surrounded by a region of inhibited diffusion (e.g., a supernova remnant, pulsar wind nebula, or TeV halo) that prevents the transport of these 𝑒⁺⁢𝑒⁻ to Earth. Because the high-electron density in these regions produces bright synchrotron and inverse-Compton emission, we conclude that all nearby pulsars are detectable as (potentially unassociated) radio, x-ray or 𝛾-ray sources.

Axionlike particles (ALPs) can be produced in the hot dense plasma of fireballs that develop in the initial stage of γ-ray burst (GRB) outflows. They can transport an enormous amount of energy away from the jet by propagating out of the fireball. The photons produced by the eventual decay of such ALPs do not reach a sufficient density to rethermalize through pair production, preventing fireball Re-emergence. Thus, the production of heavy ALPs disrupts the fireball and dims GRBs, allowing bright GRB observations to strongly constrain the existence of heavy ALPs. By adding ALP interactions to existing models of GRB fireballs, we set competitive bounds on the ALP-photon coupling down to gaγγ ∼ 4 × 10−12 GeV−1 for ALPs in the mass range of 200 MeV–5 GeV.

We present the first systematic study of explosive dispersal outflows (EDOs) as potential sources of high-energy emission in the Milky Way. EDOs are energetic outflows produced during dynamical interactions in young, massive star-forming regions, and their physical conditions make them promising environments for cosmic-ray acceleration. Using 16 yr of 0.2-500 GeV Fermi-Large Area Telescope observations, we study the γ-ray properties of seven EDOs. Three EDOs, DR21, G34.26+0.15, and G5.89−0.39, show spatially coincident GeV emission, while the remaining systems yield nondetections. Among the sample, DR21 stands out as the brightest candidate, with a detection significance ≥40σ. Its spectrum is well described by a power law with an exponential cutoff, and the integrated luminosity in the 0.1-500 GeV band is Lγ ≃ 2 × 1035 erg s−1. When compared with the outflow’s estimated kinetic energy, the inferred cosmic-ray acceleration efficiency is ≤15%, consistent with values for shocks in dense molecular environments. The energetics and morphology support an association between the DR21 molecular outflow and the observed γ-rays. Our results demonstrate that EDOs span a wide range of γ-ray luminosities and efficiencies, suggesting they may contribute to the Galactic cosmic-ray budget. This motivates searches for additional EDOs and improved multiwavelength characterization of their environments.

We show that stars in the inner parsec of the Milky Way can be significantly affected by dark matter annihilation, producing population-level effects that are visible in a Hertzsprung-Russell (HR) diagram. We establish the dark HR diagram, where stars lie on a new stable dark main sequence with similar luminosities, but lower temperatures, than the standard main sequence. The dark matter density in these stars continuously replenishes, granting these stars immortality and solving multiple stellar anomalies. Upcoming telescopes could detect the dark main sequence, offering a new dark matter discovery avenue.

Short gamma-ray bursts (GRBs) are some of the brightest transients in the universe. Heavy axionlike particles (ALPs) can be produced in the hot plasma of GRB fireballs and escape, transporting energy away the from the source. When they decay outside the source, the resulting photon field is too rarefied to re-thermalize, effectively preventing the re-emergence of the fireball, thus dimming or disrupting GRBs. Using existing observations of short GRBs, we place competitive bounds reaching ALP-photon couplings of g_aγγ ∼ 4 × 10⁻¹² GeV⁻¹ for ALP masses in the range of m_a = 200 MeV − 5 GeV.

We analyze 15 years of Fermi-LAT data and produce a detailed model of the Sun’s inverse-Compton scattering emission (solar halo), which is powered by interactions between ambient cosmic-ray electrons and positrons with sunlight. By developing a novel analysis method to analyze moving sources, we robustly detect the solar halo at energies between 31.6 MeV and 100 GeV, and angular extensions up to 45° from the Sun, providing new insight into spatial regions where there are no direct measurements of the Galactic cosmic-ray flux. The large statistical significance of our signal allows us to subdivide the data and provide the first 𝛾-ray probes into the time variation and azimuthal asymmetry of the solar modulation potential, finding time-dependent changes in solar modulation both parallel and perpendicular to the ecliptic plane. Our results are consistent with (but with independent uncertainties from) local cosmic-ray measurements, unlocking new probes into astrophysical processes near the solar surface.

The height of the Milky Way diffusion halo, above which cosmic-rays can freely escape the galaxy, is among the most critical, yet poorly known, parameters in cosmic-ray physics. Measurements of radioactive secondaries, such as 10Be or 26Al, which decay equivalently throughout the diffusive volume, are expected to provide the strongest constraints. This has motivated significant observational work to constrain their isotopic ratios, along with theoretical work to constrain the cross-section uncertainties that are thought to dominate radioactive secondary fluxes. In this work, we show that the imprecise modelling of the Milky Way spiral arms significantly affects our ability to translate 10Be and 26Al fluxes into constraints on the diffusive halo height, biasing our current results. Utilizing state-of-the-art spiral arms models we produce new predictions for the 10Be and 26Al fluxes that motivate upcoming measurements by AMS-02 and HELIX.

Thermal dark matter models generically include the prompt creation of highly concentrated dark matter cusps in the early Universe. Recent studies find that these cusps can survive to the present day, as long as they do not fall into extremely dense regions of baryonic structure. In this work, we build models of dark matter annihilation within the prompt cusps that reside in galaxy clusters, showing that they dominate the total 𝛾-ray annihilation signal. Using 15 years of Fermi Large Area Telescope data, we find no evidence for a 𝛾-ray excess from these sources, and set strong constraints on annihilating dark matter. These constraints generically rule out the thermal annihilation cross section to the 𝑏⁢¯𝑏 channel for dark matter masses below  ∼200  GeV.