Researchers using the H.E.S.S. observatory in Namibia have detected the highest energy gamma rays ever from a dead star called a pulsar. The energy of these gamma rays clocked in at 20 tera-electronvolts, or about 10 trillion times the energy of noticeable light. Researchers think that the source of this radiation are quick electrons produced and accelerated in the pulsars magnetosphere, while traveling toward its periphery. The Vela pulsar, located in the Southern sky in the constellation Vela (sail of the ship), is the brightest pulsar in the radio band of the electromagnetic spectrum and the brightest consistent source of cosmic gamma rays in the giga-electronvolts (GeV) variety. Above a few GeV, its radiation ends quickly, probably because the electrons reach the end of the pulsars magnetosphere and escape from it.
Using the H.E.S.S. observatory in Namibia, researchers have actually spotted remarkably high-energy gamma rays from the Vela pulsar, challenging established theories on pulsed gamma rays from such stars. These gamma rays, with energy levels 200 times more powerful than any previous observations from the Vela pulsar, have actually prompted researchers to reconsider the mechanisms behind such powerful emissions.
H.E.S.S. observatory records 20 tera-electronvolts photons from the Vela pulsar.
Scientists utilizing the H.E.S.S. observatory in Namibia have discovered the greatest energy gamma rays ever from a dead star called a pulsar. The energy of these gamma rays clocked in at 20 tera-electronvolts, or about 10 trillion times the energy of visible light. This observation is tough to reconcile with the theory of the production of such pulsed gamma rays, as the international team reports today (October 5) in the journal Nature Astronomy.
The Nature of Pulsars
Pulsars are the left-over corpses of stars that amazingly exploded in a supernova. The surges leave a tiny, dead star with a size of just some 20 kilometers, rotating endowed and incredibly fast with a huge magnetic field. “These dead stars are practically totally made up of neutrons and are exceptionally thick: a teaspoon of their product has a mass of more than 5 billion tonnes, or about 900 times the mass of the Great Pyramid of Giza,” explains H.E.S.S. researcher Emma de Oña Wilhelmi, a co-author of the publication operating at DESY
The scientists think that infrared light particles (photons) from the poles of the pulsar are improved to gamma-ray energies (blue) by quick electrons. Credit: Science Communication Lab for DESY.
Radiation from Pulsars
Pulsars give off turning beams of electromagnetic radiation, rather like cosmic lighthouses. If their beam sweeps across our solar system, we see flashes of radiation at regular time periods. These flashes, likewise called pulses of radiation, can be browsed for in different energy bands of the electro-magnetic spectrum. Researchers believe that the source of this radiation are quick electrons produced and accelerated in the pulsars magnetosphere, while taking a trip toward its periphery. The magnetosphere is comprised of plasma and electro-magnetic fields that surround and co-rotate with the star. “On their outward journey, the electrons obtain energy and release it in the form of the observed radiation beams,” says Bronek Rudak from the Nicolaus Copernicus Astronomical Center (CAMK PAN) in Poland, also a co-author.
The Vela pulsar, located in the Southern sky in the constellation Vela (sail of the ship), is the brightest pulsar in the radio band of the electro-magnetic spectrum and the brightest relentless source of cosmic gamma rays in the giga-electronvolts (GeV) variety. It turns about eleven times per second. However, above a few GeV, its radiation ends quickly, most likely since the electrons reach the end of the pulsars magnetosphere and escape from it.
This is not the end of the story: utilizing deep observations with H.E.S.S., a brand-new radiation element at even greater energies has now been discovered, with energies of up to tens of tera-electronvolts (TeV). “That is about 200 times more energetic than all radiation ever identified before from this item,” states co-author Christo Venter from the North-West University in South Africa. This extremely high-energy element appears at the very same stage intervals as the one observed in the GeV variety. However, to obtain these energies, the electrons might need to travel even farther than the magnetosphere, yet the rotational emission pattern requires to remain intact.
Challenging Established Knowledge
” This result challenges our previous understanding of pulsars and requires a reconsidering of how these natural accelerators work,” says Arache Djannati-Atai from the Astroparticle & & Cosmology (APC) laboratory in France, who led the research.
” The conventional scheme according to which particles are sped up along electromagnetic field lines within or somewhat outside the magnetosphere can not sufficiently explain our observations. Possibly we are witnessing the velocity of particles through the so-called magnetic reconnection procedure beyond the light cylinder, which still somehow preserves the rotational pattern? Even this situation deals with troubles in discussing how such extreme radiation is produced.”
Whatever the explanation, next to its other superlatives, the Vela pulsar now formally holds the record as the pulsar with the highest-energy gamma rays discovered to date. “This discovery opens a brand-new observation window for detection of other pulsars in the 10s of teraelectronvolt range with current and upcoming more delicate gamma-ray telescopes, thus paving the method for a much better understanding of the extreme acceleration processes in extremely allured astrophysical things,” says Djannati-Atai.
Recommendation: “Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts” 5 October 2023, Nature Astronomy.DOI: 10.1038/ s41550-023-02052-3.
