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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Uberising solar energy
A team of students from Strathmore University in Nairobi, Kenya on Thursday walked off as winners with R20 000 in prize money for an innovative concept to provide equitable energy access to remote villages based on, among others, “Uber(ising) solar energy.”
The team was one of four university teams participating in the African Utility Week and Powergen Africa conference and exhibition’s first ever Initiate! Impact Challenge. The 19th edition of the event gathered thousands of power, water and gas industry experts in Cape Town this week and ended on Thursday.
Student teams from Stellenbosch University, the University of Cape Town and the University of the Witwatersrand also took part in the three-day challenge sponsored by the Enel Foundation, the Innovation Hub, Lesedi Nuclear Services and the Russian Nuclear Agency Rosatom. The Initiate! Challenge aimed to create a platform for students and start-ups to drive innovation and share ideas for the energy sector.
The Strathmore University team included engineering students Ignatius Maranga, Raymond Kiyegga, Fredrick Amariati and Alex Osunga. One member of the team will also have the exclusive opportunity to join the 5th annual student fact-finding mission to Russia to visit several state-of-the-art nuclear facilities and dedicated Russian nuclear universities. Maranga said the team is happy and humbled especially because they competed against some of the top universities on the continent. He said the teams’ winning idea is rooted in real life challenges that Kenyans in rural areas face. “The solutions offered so far to expand energy access are not solving these problems as many are not financially viable.”
The team’s idea is to put a solar panelled container in rural villages that will also house a clinic and a knowledge hub like a school for vocational training to teach people about the use and benefits of solar energy. It will also include a shop where villagers can buy daily essentials like milk.
Maranga said: “The school will help with capacity building as villagers will see and learn benefits of electricity and as the business grows, they will want to have electricity in their homes and when that point comes, we will have solar powered tricycles. These tricycles will carry and deliver batteries like Uber does passengers to villagers in more remote areas. The system is modular so we will add another container to charge batteries. These batteries are ferried on trikes, so villagers in more remote areas can request a number of charged batteries on their phone.”
Maranga explained that it is common cause that Africa is big, and many people live in remote rural villages. “So, it is not always possible to extend the power grid to these areas as it is very expensive. So, what do we do instead? Most people own a cell phone, and everyone needs electricity, so you take it to them. They cannot exactly carry a battery for two kilometres so why then not Uber a battery?” Maranga said their company Kijiji, (Swahili for village) will now look at commercialising their idea, optimise it and do market tests. “If accepted we want to roll it out depending on funding.”
The team’s idea appealed to the judges because it was a simple idea that is easy to replicate beyond Kenya to the rest of the continent. Chief executive officer of Rosatom Central and Southern Africa, Dmitry Shornikov, said: “We are very pleased with the solutions presented by the students. The maturity and depth of their research gives us great hope and proves that young Africans really are devoted to solving Africa’s energy challenges.”
Business Development executive at Lesedi Nuclear Services, Shane Pereira, in an earlier interview said the company partnered with Initiate! because it is dedicated to the youth that will be the leaders of tomorrow. “The growth and development as well as training, coaching and mentoring of the youth is critical to the success of our future economy.”
The ideas of the other three teams focused more on mitigating the risk of climate change and came up with ideas ranging from vertical farms to energy boxes.
Race to 8K TV is on
TV brands are all rolling-out 8K displays. Even if you don’t want it, the race is real, writes ARTHUR GOLDSTUCK
It’s the most near-perfect technology ever for watching TV, but there is almost no reason for the average consumer to invest in it. It’s called 8K, and it offers double the resolution of the current high-end, known as 4K, which itself offers twice the resolution of regular high-definition TV.
It sounds incredible, and it is. One has to step right up to an 8K screen, with ones nose almost to the glass, before one can see the tiny grid that makes up the display pattern. Where HD has 1920 horizontal lines down the TV screen, 4K has 3840, and 8K 7680 lines. When multiplied by vertical lines – HD at 1080, 4k at 2160 and 8K at 4320 – one sees an exponential increase in the number of pixels. These light elements that make up the picture leap from 2-million in HD to 33-million in 8K.
There is one fundamental problem with this dramatic leap in display technology: the world of content has yet to catch up with it. So, unless one has money to burn and an appetite for showing off, there is little point in buying an 8K set – for now.
What it really represents is the TV manufacturing industry demonstrating both its readiness for the content revolution, and its ability to lead in technology. This means that, because a Samsung or LG unveils an 8K unit, consumers will have their perception of that company’s technology leadership reinforced, and feel more compelled to buy one of their lower-end TVs.
The further reality is that the new cutting edge technology that gets announced today is the mainstream technology three years from now and the entry-level in five to ten years. When the first OLED display was unveiled by Sony at the Consumer Electronics Show in Las Vegas a decade ago, a tablet-sized screen would have cost $20 000, or nearly R300 000 in today’s money. Yet, the same technology is now available in large-screen TVs for less than R10,000. A few years on, Samsung and LG unveiled the next big thing, Quantum Dot TV screens, at well over R50,000. Now Samsung’s version, called QLED, and HiSense, with ULED, are available for under R10 000.
In other words, the price of the cutting edge keeps coming down, and each new cutting edge drops in price faster than the one before.
So, when Samsung announced recently that it’s new QLED 4K and 8K TV models will be available at select retailers in South Africa from this month, it wasn’t mere hype.
Samsung argued that the 2019 editions of the Q80 and Q90 feature “Ultra Viewing Angle technology, which restructures the TV’s panels so the backlight passes through the panel with lights evenly onto the screen”.
The Q70, Q80, and Q90 models offer “Direct Full Array technology that uses a panel featuring concentrated zones of precision-controlled LEDs”. These adjust automatically to display deeper blacks and purer whites, delivering dramatically improved contrast.
Users of the Q900 model series won’t have to wait for content to be made in 8K format either. It uses the company’s Quantum Processor 8K to “up-scale” lower resolution content to 8K and optimises audio and video to the specific content on the screen.
In the same way, the QLED 4K models feature Quantum Processor 4K, which up-scales HD to improve brightness, picture quality and sound, based on each individual scene.
Meanwhile, at a Global Press Conference in Andalusia, Spain, last month, the organisers of the annual IFA tech fest in Berlin gave the media a sneak preview of what to expect at the event in September. Top of the list was 8K TV.
Hisense and Skyworth both signalled their intentions to join the 8K TV technology race, but at a far more affordable level than the industry leaders.
Hisense showcased the 74U9E 8K TV, a 75-inch monster that is due to be launched in China this year, and is likely to come to South Africa early next year.
It offers improved contrast and more vivid colours over the previous Hisense U range TV, while sound is integrated, with a subwoofer embedded into the stand of the TV. Like the Samsung 8K machines, the display dynamically upscales 4K content in real time.
At the IFA press conference, Skyworth showcased its 8K TVs via German TV brand Metz, which it acquired last year. The company offers a “premium-affordable” sub-brand called Metz Blue and, startlingly, this low-cost brand was chosen to showcase 8K TV, meaning it will reach the mass market even more quickly than previous high-end technologies.
With Skyworth having brought the first Android-based TV to South Africa last year, it came as no surprise that its new S9A 8K OLED is an Android TV, combining vivid picture colour with Android TV functionality. As Gadget’s Bryan Turner, who attended the event, put it: “Witnessing the 8K and OLED combination was incredible and felt like getting a new set of glasses.”
It supports the latest streaming apps, and can be controlled via the voice-controlled Google Assistant, which is available on most Android phones.
In short, 8K is on a fast-track to our living rooms, at a speed never seen before in cutting edge TV.
- Arthur Goldstuck is founder of World Wide Worx and editor-in-chief of Gadget.co.za. Follow him on Twitter and Instagram on @art2gee