Caught in the Act: AGN flares are everywhere
February 2022 When we observe the sky in gamma rays of the highest energies, most of the sources outside of our Milky Way turn out to be the central regions of other galaxies. These…
Hunting for the gamma-ray counterparts to binary black hole mergers
January 2022 Gravitational Waves (GWs) are produced by the coalescence of compact objects like neutron stars and black holes. These events are in no doubt in the list of the most cataclysmic events in…
HESS J0632+057: from discovery to detailed exploration
December 2021 The majority of stars around us are gravitationally bound in stellar binary systems. If the two stars are close enough, in rare cases we see variable emission from the outflowing matter from…
HESS J1930+188: The high energy side of the Bull’s Eye Pulsar Wind Nebula
November 2021 With the first sources published by the LHAASO experiment this year, the number of observatories studying the cosmos at very high photon energies has grown further. This allows comparisons for cross-validations and…
Unveiling new H.E.S.S. sources
October 2021 The H.E.S.S. Galactic Plane Survey — or HGPS for short H.E.S.S.-SOM 2016-01, [1] — has been a very successful project. It has resulted in a very large number of γ-ray sources, many…
N132D: a cosmic-ray marathoner
September 2021 The atmosphere on Earth is continuously bombarded by energetic particles originating from outside the Solar System. Somewhat confusingly, we call these particles ‘cosmic rays’. These particles are the reason why astronauts and…
An active proton PeVatron hiding inside HESS J1702-420?
August 2021 More than a century after their discovery in 1912 [1], the origin of cosmic rays remains one of the oldest unsolved mysteries in physics. The bulk of cosmic rays reaching the Earth…
Tracking UFOs with H.E.S.S.
July 2021 In 1937 Fritz Zwicky measured the velocities of galaxies in the Coma cluster of galaxies and deduced that the total mass of this cluster is considerably higher than the combined mass of…
GRB 190829A: A long-lasting explosion offers surprises
June 2021 Gamma-ray bursts (GRBs) are bright X-ray and gamma-ray flashes observed in the sky, emitted by distant extragalactic sources. They are associated with the collapse of rapidly rotating massive stars, in which a…
A large armada targets famous M87
May 2021 In April 2019 the Event Horizon Telescope (EHT) team presented the first image of the shadow of the supermassive black hole inside the famous galaxy M87 [1]. This spectacular result was made…