Max Planck Institute for Nuclear Physics (MPIK) | via Interactions.org | 2015 Jan 22
[c][attachment=0]LMC_Mellinger_optical_Halpha_HESS[1].jpg[/attachment][/c]Once again, the High Energy Stereoscopic System, H.E.S.S., has demonstrated its excellent capabilities. In the Large Magellanic Cloud, it discovered the most luminous very high-energy gamma-ray sources: three objects of different types, namely the most powerful pulsar wind nebula, the most powerful supernova remnant, and a shell 270 light-years in diameter blown by multiple stars and supernovae -- a so-called superbubble. This is the first time that stellar-type gamma-ray sources are detected in an external galaxy at these gamma-ray energies. The superbubble represents a new source class in very high-energy gamma rays.
Very high-energy gamma rays are the best tracers of cosmic accelerators such as supernova remnants and pulsar wind nebulae -- end-products of massive stars. There, charged particles are accelerated to extreme velocities. When these particles encounter light or gas in and around the cosmic accelerators, they emit gamma rays. Very high-energy gamma rays can be measured on Earth by observing the Cherenkov light emitted from the particle showers produced by incident gamma rays high up in the atmosphere using large telescopes with fast cameras.
The Large Magellanic Cloud (LMC) is a dwarf satellite galaxy of our Milky Way, located about 170,000 light-years away and showing us its face. New, massive stars are formed at a high rate in the LMC, and it harbors numerous massive stellar clusters. The LMC’s supernova rate relative to its stellar mass is five times that of our galaxy. The youngest supernova remnant in the local group of galaxies, SN 1987A, is also a member of the LMC. Therefore, the H.E.S.S. scientists dedicated significant observation to searching for very high-energy gamma rays from this cosmic object.
For a total of 210 hours, the High Energy Stereoscopic System (H.E.S.S.) has observed the largest star-forming region within the LMC called Tarantula Nebula. For the first time in a galaxy outside the Milky Way, individual sources of very high-energy gamma rays could be resolved: three extremely energetic objects of different type. ...
The exceptionally powerful TeV γ-ray emitters in the Large Magellanic Cloud - H.E.S.S. Collaboration
- Science 347(6220) 406 (23 Jan 2015) DOI: 10.1126/science.1261313