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Tag archives: black hole

HAWC spots TeV gamma ray flare

A TeV gamma-ray flare spotted by HAWC

Now you see it, now you don’t: a TeV gamma-ray flare spotted by HAWC. (Courtesy: Michelle Hui)

By Hamish Johnston at the APS April Meeting in Salt Lake City 

Talk about luck. Just 10 days before the April Meeting the High-Altitude Water Cherenkov (HAWC) gamma-ray observatory lit up with the detection of a galaxy that produced large numbers of teraelectronvolt (TeV) gamma rays for just one day (see image).

Dubbed Markarian 501, HAWC astrophysicists believe that the flare could be driven by a supermassive black hole at the centre of the galaxy. However, they admit that they don’t really understand how such flares occur.


Posted in APS April Meeting 2016 | Tagged , , , | 1 Comment | Permalink
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Soft hair on black holes, making concrete on Mars and exploring the cosmos in 2016

By Hamish Johnston


This week’s Red Folder looks to the cosmos, starting with a spiffy new video from the European Space Agency. The slick presentation is a preview of some of the extra-terrestrial exploits that the agency has planned for 2016. This includes the landing of the Schiaparelli probe on the surface of Mars. This stationery lander will survey its Martian environs to find a suitable location to drop the ExoMars rover in 2018. The mission’s namesake is the Italian astronomer Giovanni Schiaparelli, who mapped the surface of Mars and was the first to use the term canali to describe the straight lines that were thought to exist on the surface of the planet.

It’s possible that someday humans will colonize Mars and this will involve building dwellings and other structures on the Red Planet. In preparation, Lin Wan, Roman Wendner and Gianluca Cusatis at Northwestern University in the US have come up with a recipe for making concrete on Mars. The trio reckon that any successful colonization of the Red Planet will have to rely on local building materials because shipping stuff from Earth would be horrendously expensive.


Posted in The Red Folder | Tagged , , , , | 3 Comments | Permalink
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First image of a black hole expected a year from now

Chalk art of a black hole at the Perimeter Institute for Theoretical Physics (PI).

Chalk art of a black hole at the Perimeter Institute for Theoretical Physics (PI).

By Louise Mayor in Waterloo, Canada

According to Avery Broderick, a physicist at the University of Waterloo and the Perimeter Institute for Theoretical Physics (PI) in Canada, the iconic picture of a black hole from the film Interstellar “really only presages astronomical reality by about a year”. That’s because, as Broderick explains, “as soon as next spring the Event Horizon Telescope is gonna produce images of the black hole at the centre of the Milky Way”.


Posted in Convergence 2015 | Tagged , , , , | 5 Comments | Permalink
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What do strange metals and black holes have in common?

Subir Sachdev

Subir Sachdev.

By Hamish Johnston in Waterloo, Canada

Harvard’s Subir Sachdev has just taken the audience here at the Convergence conference on a delightful romp through the phase diagram of the cuprate high-temperature superconductors. What I found most interesting was not the superconducting phase, but rather Sachdev’s description of the “strange metal” phase.

This phase occurs when the cuprate copper-oxide layer is highly doped with holes and has perplexed physicists for some time – hence its strange moniker. It has no quasiparticles and lots of low-energy excitations so there is no easy way to describe the collective behaviour of the electrons.


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The Dark Matter Garden, gravitational atoms, boys and girls with toys, and more

Gravitational gardening: the Dark Matter Garden at Chelsea

Gravitational gardening: the Dark Matter Garden at this year’s RHS Chelsea Flower Show. (Courtesy: National Schools’ Observatory)

By Hamish Johnston

Gardening is something that the British take very seriously and this week’s RHS Chelsea Flower Show is the pinnacle of that obsession. Indeed, it is so popular that it is covered live on television by the BBC. One highlight of the show is the garden competition, in which designers transform an empty plot into a dazzling garden in just 10 days. This year’s entries include the Dark Matter Garden, which “brings the mysteries of the universe to Chelsea”. That’s the claim of the designers of the garden (including several astronomers), who built it for the UK’s National Schools’ Observatory. The team says that its gold-medal-winning design includes “innovative structures and planting, and represents the effect of dark matter on light”.


Posted in The Red Folder | Tagged , , | 3 Comments | Permalink
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Heavy-metal Higgs, meet the Publons, Stephen Hawking’s galactic tour and more

By Tushna Commissariat and Hamish Johnston

I’m sure that most of you have wondered what the Higgs boson would sound like if it were a heavy-metal song. Now you can turn it up to 11 (TeV that is) courtesy of CERN physicist and guitarist Piotr Traczyk, who has “sonified” data from two plots from the CMS experiment that were presented at the Higgs discovery seminar on 4 July 2012. His heavy-metal ditty is based on gamma–gamma and 4-lepton data from CMS and after you listen to his excellent song in the above video, you can find out more about how it was created by reading this entry by Traczyk on the Cylindrical Onion blog.


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You spin me right round

By Tushna Commissariat

It’s not often that we come across a mention of an astronomical event measured in Earth years, let alone months or hours. So suffice to say I was pretty surprised by a recent XMM-Newton finding that talked about a star orbiting a black hole at the furious rate of once every 2.4 hours! Further investigation revealed that this has only broken the previous record by an hour, but these extremely short orbits still have me rather amazed. Certain short orbital period binary stars or pulsars do have even shorter periods of less than an hour, but this star orbits a stellar-mass black hole (it’s about three times more massive than the Sun) that is roughly a million kilometres away from it. The video below, courtesy of the European Space Agency (ESA), is an animation showing one complete orbit of the star.


Posted in General | Tagged , , , , | 2 Comments | Permalink
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60 Second Adventures in Astronomy

By Hamish Johnston

If you are a fan of astronomy and the comedian David Mitchell, the Open University has a treat for you. Mitchell and the OU have made a series of 12 short animated videos about the physics of the cosmos.


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Talking about gravitation


By Tushna Commissariat

As I was looking through all that is new and exciting in the world of physics this morning, I came across this interesting paper titled “Persistence of black holes through a cosmological bounce”, recently published on the arXiv preprint server. The paper looks at the possibility of certain black holes persisting when the universe collapses in a “big crunch”, only to stick around for the universe to re-expand with a “big bounce”. The paper was written specifically for the 2011 Awards for Essays on Gravitation held by the Gravity Research Foundation. Upon investigation, I found another two submissions published on arXiv, entitled “Birkhoff’s theorem in higher derivative theories of gravity” and “Quantum gravity and the correspondence principle”.

The Gravity Research Foundation was founded by Roger W Babson, a graduate from the Massachusetts Institute of Technology, who had an interesting relationship with gravity. In his youth, his older sister drowned in a river near their home, prompting him to write an essay titled “Gravity – our enemy no. 1” wherein he claimed that it was gravity that killed her. “She was unable to fight gravity, which came up and seized her like a dragon and brought her to the bottom” he wrote.

Later he owed a debt of sorts to the theory of gravity as it helped him to predict the 1929 stock market crash based on the principle that if there was a strong upward action, there would follow a severe downward reaction. “What goes up will come down” he said. “The stock market will fall by its own weight.”

Gravity was a neglected area of physics in the 1940s. To energize the field, at the encouragement of his colleague George Rideout, he set up the Gravity Research Foundation, which handed out the first awards for the best essays submitted on gravity in December 1949. Previous prizewinners include Stephen Hawking (who has won it six times) and British science writer and astronomer John Gribbin (who was co-author of the winning paper, with Paul Feldman, when Gribbin was only 24) An archive of all winning essays can be found on the foundation’s website.

This year will be the 62nd year of the Essay Award and they will be announcing the top five prizewinners on 15 May, so all the best to the participants. And do look out for a follow-up blog!

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