In the latest discovery, the H.E.S.S. (a telescope that is operated by an international collaboration of scientists) has found three extremely luminous gamma-ray sources in the Large Magellanic Cloud (LMC), a satellite dwarf galaxy of the Milky Way.
These are objects of different types, namely the most powerful pulsar wind nebula; the most powerful supernova remnant; and a shell of 270 light years in diameter blown by multiple stars, and supernovae – a so-called superbubble.
The discovery is announced in the latest edition of the scientific journal, Science, in a research paper titled: The exceptionally powerful TeV ƴ-ray emitters in the Large Magellanic Cloud, which was published on Friday, 23 January 2015.
“This is a very important breakthrough for the team,” says Professor Sergio Colafrancesco, DST/NRF SKA Research Chair in the Wits School of Physics. “It paves the way to study external galaxies with very high-E telescopes such as H.E.S.S and then later with the planned Cherenkov Telescope Array (CTA) in Namibia. It will lead us to re-examine galaxy evolution and answer questions such as how high-E particles can affect the evolution of cosmic structures in the universe, principally galaxies, and the life cycles of matter in galaxies,” he adds.
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, 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 types.
The so-called superbubble 30 Dor C is the largest known X-ray-emitting shell and appears to have been created by several supernovae and strong stellar winds. Superbubbles are broadly discussed as (complementary or alternative to individual supernova remnants) factories where the galactic cosmic rays are produced. The H.E.S.S. results demonstrate that the bubble is a source of, and filled by, highly energetic particles. The superbubble represents a new class of sources in the very high-energy regime.
Pulsars are highly magnetized, fast rotating neutron stars that emit a wind of ultra-relativistic particles forming a nebula. The most famous one is the Crab Nebula, one of the brightest sources in the high-energy gamma-ray sky. The pulsar PSR J0537−6910 driving the wind nebula N 157B discovered by the H.E.S.S. telescopes in the LMC is in many respects a twin of the very powerful Crab pulsar in our own Galaxy. However, its pulsar wind nebula N 157B outshines the Crab Nebula by an order of magnitude, in very high-energy gamma rays. Reasons are the lower magnetic field in N 157B and the intense starlight from neighboring star-forming regions, which both promote the generation of high-energy gamma rays.
The supernova remnant N 132D, known as a bright object in the radio and infrared bands, appears to be one of the oldest – and strongest – supernova remnants still glowing in very high-energy gamma rays. Between 2500 and 6000 years old – an age where models predict that the supernova explosion front has slowed down and it ought no longer to be efficiently accelerating particles – it still outshines the strongest supernova remnants in our Galaxy. The observations confirm suspicions raised by other H.E.S.S. observations, that supernova remnants can be much more luminous than thought before.
Observed at the limits of detectability, and partially overlapping with each other, these new sources challenged the H.E.S.S. scientists. The discoveries were only possible due to the development of advanced methods of interpreting the Cherenkov images captured by the telescopes, improving in particular the precision with which gamma-ray directions can be determined.
Indeed, the new H.E.S.S. II 28 m telescope will boost the performance of the H.E.S.S. telescope system, and in the more distant future the planned Cherenkov Telescope Array (CTA) will provide even deeper and higher-resolution gamma-ray images of the LMC – in the plans for science with CTA, the satellite galaxy is already identified as a “Key Science Project” deserving special attention.
· The H.E.S.S. telescope is operated by an international collaboration of scientists with a strong involvement by South African universities, in particular Wits University, North West University, and the Universities of the Free State and Johannesburg. Wits physicists are particularly involved in data analysis techniques, the development of theoretical interpretation tools of both extragalactic and galactic sources, and in the operational shifts at the telescope location in Namibia.
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VR becomes business tool
By Darren Cohen, associate partner and portfolio lead for reality science at Business Science Corporation
A significant challenge facing mining and other industries is skills development and the question of how to move the needle when it comes to ensuring memory retention in safety training. Virtual Reality (VR) technology offers a solution that is both more efficient and more effective at skills transfer, which can sometimes be a matter of life and death.
VR is an established and proven technology. However, historically, VR has largely existed in the realm of the gaming industry, where the technology has been developed and refined. Beyond its impressive “wow factor”, VR is no longer just a fad. Recent technological advancements have opened VR to applications as a mainstream business tool that can save organisations time and money and assist in skills transfer.
This is of special importance in the mining industry, which has taken great strides to improve its safety record, but still faces safe-production challenges, as evidenced by the recent spate of incidents and fatalities at several South African mines during this year.
VR technology provides a fully immersive 3D experience, giving participants a sense of really being in the environment they are viewing. Sensors in the Head Mounted Display (HMD) track motion as the participant’s head moves and alter vision accordingly. Participants gain hands-on experience in a safe, controlled virtual environment that closely replicates the real world in which they will be working, in ways that have never been possible with traditional 2D training media. This allows participants to become completely familiar with even the most dangerous working environments, in complete safety.
Click here to read about how VR
Nine years later, Nintendo set to lead again
Nintendo is set to regain its leadership position in video game consoles for the first time since 2009, according to the latest projections from Strategy Analytics’ Connected Home Devices service.
The report, Global Game Console Market Forecast, predicts that Nintendo will sell 17.3 million Switch consoles worldwide in 2019, while Sony will sell 17.1 million PS4 and PS4 Pro consoles. Microsoft will remain in third place, selling 10.0 million Xbox One and Xbox One X devices. The overall console market has performed well in 2018, with total global sales reaching 46.1 million devices, the highest level since 2010.
Other key findings from the report include:
- Sony is still the market leader in terms of consoles in use; it accounts for nearly half of all video games consoles in use, and 84% of these are now PS4 or PS4 Pro devices
- Video game console ownership has been rising again in recent years; 45% of North American homes and 20% of Western European homes now own at least one console
- The global retail value of the games console business is predicted to reach $15.4bn in 2018, an increase of 7.6%
- 2019 revenues are expected to decline by 10% as shipment volumes and prices fall
- By 2023 revenues will return to 2018 levels, driven by the launch of next generation systems such as the PS5 and Xbox and Switch updates
David Watkins, Director at Strategy Analytics, commented, “Contrary to some expectations, the global TV games console market remains healthy. Many pundits have written it off over the years, for reasons ranging from the emergence of cloud gaming to the dominance of mobile devices and the arrival of VR, but it refuses to die. In fact, there is an argument that the enduring appeal of the TV games console, now in its sixth decade, continues to demonstrate the weaknesses and limitations of alternative games platforms.”
Chirag Upadhyay, Senior Analyst at Strategy Analytics, added, “Console upgrade cycles continue, and the three-way battle between Sony, Microsoft and Nintendo, which has been raging now for the best part of two decades, shows no sign of abating as each platform owner discusses its plans for updates and new generations. In partnership with developers and driven by the ever-rising expectations of consumers we fully expect these platform owners to continue to push the boundaries of the large screen gaming experience for many more years to come.”