Scientists detect highest energy gamma rays from a dead star called Vela Pulsar

Scientists have made an extraordinary discovery using the H.E.S.S. observatory in Namibia, detecting the highest-energy gamma rays ever emitted by a dead star known as the Vela Pulsar. The results of this groundbreaking observation were announced by an international team and published in the journal Nature Astronomy on October 5th. These gamma rays from the Vela Pulsar were found to possess an astonishing energy level of 20 tera-electronvolts, which is equivalent to approximately ten trillion times the energy of visible light.

Pulsars are remnants of massive stars that have undergone explosive supernova events. These cataclysmic explosions leave behind incredibly dense, tiny stars with diameters of about 20 kilometers. Composed primarily of neutrons, these dead stars are exceptionally dense, with just a teaspoon of their material weighing more than five billion tonnes—roughly 900 times the mass of the Great Pyramid of Giza, according to H.E.S.S. scientist Emma de Oña Wilhelmi, who is a co-author of the study.

Pulsars act as cosmic lighthouses, emitting beams of electromagnetic radiation that rotate like cosmic lighthouses. When these beams intersect with our solar system, we observe periodic flashes of radiation, referred to as pulses. As Bronek Rudak from the Nicolaus Copernicus Astronomical Center (CAMK PAN) in Poland, another co-author, explained, “On their outward journey, the electrons acquire energy and release it in the form of the observed radiation beams.”

The Vela Pulsar, located in the Southern sky within the constellation Vela, stands out as the brightest pulsar in the radio portion of the electromagnetic spectrum and the most significant source of cosmic gamma rays in the giga-electronvolts (GeV) range. It rotates approximately eleven times per second and was previously believed to cease emitting radiation above a few GeV, possibly due to electrons reaching the magnetosphere’s edge and escaping.

However, in-depth observations with H.E.S.S. have unveiled a previously unknown radiation component at even higher energies, reaching tens of tera-electronvolts (TeV). As co-author Christo Venter from the North-West University in South Africa noted, “That is about 200 times more energetic than all radiation ever detected before from this object.”