Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First detection of gamma-ray burst afterglow in very-high-energy gamma light

21.11.2019

Gamma-ray bursts, extremely energetic flashes following cosmological cataclysms, emit very-high-energy gamma-rays long after the initial burst. This discovery was made in July 2018 by the huge 28-m telescope of the H.E.S.S. array in Namibia.

On 20 July 2018, the Fermi Gamma-Ray Burst Monitor and a few seconds later the Swift Burst Alert Telescope notified the world of a gamma-ray burst, GRB 180720B. Immediately after the alert, several observatories turned to look at this position in the sky. For H.E.S.S. (High Energy Stereoscopic System), this location became visible only 10 hours later. Nevertheless, the H.E.S.S. team decided to search for a very-high-energy afterglow of the burst.


The huge central H.E.S.S. telescope with 614 m² mirror area and two of the four smaller telescopes, each with 107 m² mirror area.

MPIK/C. Föhr

Extremely energetic cosmic explosions generate gamma-ray bursts (GRB), typically lasting for only a few tens of seconds. The burst is followed by a longer lasting afterglow in the optical and X-ray spectral regions whose intensity decreases rapidly. The prompt gamma-ray emission is mostly composed of photons several thousand to millions of times more energetic than visible light, that can only be observed by satellite-based instruments. Whilst these space-borne observatories have detected a few photons with even higher energies, the question if very-high-energy gamma radiation (at least 100 billion times more energetic than visible light) is emitted, has remained unanswered.

This radiation has now been detected with the large H.E.S.S. telescope, that is especially suited for such observations. The data collected 10 to 12 hours after the gamma-ray burst showed a new point-like gamma-ray source at the position of the burst, which had disappeared in data taken another 18 days later. Physicists of the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg led the analysis of these data.

GRB 180720B was very strong and lasted for about 50 seconds – a relatively long duration indicating the death of a massive star. In this process, its core collapses to a rapidly rotating black hole. The surrounding gas forms an accretion disk around the black hole, with gas jets ejected perpendicularly to the disk plane creating the gamma-ray flashes.

The very-high-energy gamma radiation which has now been detected not only demonstrates the presence of extremely accelerated particles, but also shows that these particles still exist or are created a long time after the explosion. Most probably, the shock wave of the explosion act here as the cosmic accelerator. Before this H.E.S.S. observation, it had been assumed that such bursts likely are observable only within the first seconds and minutes at these extreme energies.

At the time of the H.E.S.S. measurements the X-ray afterglow had already decayed very considerably. Remarkably, the intensities and spectral shapes are similar in the X-ray and gamma-ray regions. There are several theoretical mechanisms for the generation of very-high-energy gamma light by particles accelerated to very high energies. The H.E.S.S results strongly constrain the possible emission mechanisms, but also present a new puzzle, as they request quite extreme parameters for the GRB as a cosmic accelerator.

Together with the observations of very-high-energy gamma radiation following later GRBs with MAGIC and again with H.E.S.S., this discovery provides deeper insights into the nature of gamma-ray bursts. Jim Hinton of the MPIK is enthusiastic about the new discovery: „For more than a decade, Cherenkov telescopes such as H.E.S.S. and MAGIC have searched for very-high-energy gamma radiation from GRBs and continuously improved their observation strategies. Now several GRBs have been detected at very high energies within a very short time, and the bursts are emitting at extreme energies for many hours and even days. This opens entirely new perspectives for the successor instrument CTA (Cherenkov Telescope Array), which will enable us to study these stellar explosions in much more detail.“

Wissenschaftliche Ansprechpartner:

Edna L. Ruiz Velasco
Phone: +49 6221 516-137
E-Mail: Edna.ruiz(at)mpi-hd.mpg.de

Dr. Daniel Parsons
Phone: +49 6221 516-634
E-Mail: daniel.parsons(at)mpi-hd.mpg.de

Prof. Dr. Werner Hofmann
Phone: +49 6221 516-330
E-Mail: werner.hofmann(at)mpi-hd.mpg.de

Prof. Dr. Jim Hinton
Phone: +49 6221 516-140
E-Mail: jim.hinton(at)mpi-hd.mpg.de

Originalpublikation:

H.E.S.S. Collaboration (E. L. Ruiz Velasco, Q. Piel, R. D. Parsons, E. Bissaldi, C. Hoischen, A. M. Taylor, F. Aharonian, D. Khangulyan et al.): A very-high-energy component deep in the Gamma-ray Burst afterglow, Nature 575, 464–467 (2019), DOI: 10.1038/s41586-019-1743-9

Dr. Gertrud Hönes | Max-Planck-Institut für Kernphysik
Further information:
http://www.mpi-hd.mpg.de

More articles from Physics and Astronomy:

nachricht Researchers develop first mathematical proof for key law of turbulence in fluid mechanics
12.12.2019 | University of Maryland

nachricht Weizmann physicists image electrons flowing like water
11.12.2019 | Weizmann Institute of Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Safer viruses for vaccine research and diagnosis

12.12.2019 | Health and Medicine

NTU Singapore scientists convert plastics into useful chemicals using su

12.12.2019 | Life Sciences

Studies show integrated strategies work best for buffelgrass control

12.12.2019 | Agricultural and Forestry Science

VideoLinks
Science & Research
Overview of more VideoLinks >>>