TeV flaring activity of the AGN PKS 0625–354 in November 2018
Most γ-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we…
Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433
SS 433 is a microquasar, a stellar binary system with collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.), finding an energy-dependent shift in the apparent…
Discovery of a radiation component from the Vela pulsar reaching 20 teraelectronvolts
Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories. However, many questions are still open regarding the acceleration and radiation processes involved, as well as the locations where they…
Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A
We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 22 away from the best-fit position of the IceCube neutrino event IceCube-211208A detected on 2021 December 8. The source was in a…
The vanishing of the primary emission region in PKS 1510-089
In July 2021, PKS 1510-089 exhibited a significant flux drop in the high-energy gamma-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly,…
Constraining the cosmic-ray pressure in the inner Virgo Cluster using H.E.S.S. observations of M 87
The origin of the gamma-ray emission from M 87 is currently a matter of debate. This work aims to localize the very high-energy (VHE; 100 GeV – 100 TeV) gamma-ray emission from M 87 and probe…
Constraints on the intergalactic magnetic field using Fermi-LAT and H.E.S.S. blazar observations
Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and…
Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S
Geminga is an enigmatic radio-quiet γ-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy γ-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are…
Search for the evaporation of primordial black holes with H.E.S.S.
Primordial Black Holes (PBHs) are hypothetical black holes predicted to have been formed from density fluctuations in the early Universe. PBHs with an initial mass around 1014–1015 g are expected to end their evaporation…
HESS J1809–193: a halo of escaped electrons around a pulsar wind nebula?
Context. HESS J1809−193 is an unassociated very-high-energy γ-ray source located on the Galactic plane. While it has been connected to the nebula of the energetic pulsar PSR J1809−1917, supernova remnants and molecular clouds present…