Gamma Ray Bursts Archives

August 15, 2008December 24, 2015 by Nancy Atkinson

GLAST Science Operations Underway: Now, About That Name!

Artists impression of GLAST in orbit. Credit: NASA

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After a 60-day checkout period, science operations have begun in earnest for GLAST, the Gamma ray Large Area Space Telescope, which is now surveying the gamma-ray sky. Launched on June 11, 2008, the GLAST spacecraft has been undergoing calibrations of the two instruments on board, the LAT (Large Area Telescope) and the GBM (GLAST Burst Monitor) — more details on the instruments in a moment. But during the checkout phase both instruments made significant observations of gamma rays. “Given that these detections were made with just the engineering data observations, the future is full of promise, and we are very excited,” said Dr. Steve Ritz, GLAST Project Scientist in his GLAST blog. At the end of August, there will be a formal release of the first-light images taken by the spacecraft. Also at that time, NASA will rename the observatory. I don’t know about you, but I’m sort of attached to the name “GLAST.” But it will be interesting to find out its new, official name.

In June, LAT detected two extraordinarily bright, flaring sources in space, which scientists believe are very likely supermassive black hole systems at the cores of active galaxies, located far across the universe, but incredibly bright. Additionally, by the end of July, the GBM had detected 12 gamma ray bursts.

“We are thrilled to be detecting gamma-ray bursts so early in the mission. GLAST and the GBM are off to a great start!” said Charles “Chip” Meegan, GBM principal investigator at NASA’s Marshall Space Flight Center, Huntsville, Ala. “The detectors are working well and we’re really pleased with how the instrument is working. That said, we’re using this checkout period to scrutinize the data coming down from the detectors and fine tune flight and ground software and our daily operational processes.”

The LAT detects gamma rays and is able to make gamma ray images of astronomical objects. The GBM is designed to observe gamma ray bursts, which are sudden, brief flashes of gamma rays that occur about once a day at random positions in the sky. The GBM has such a large field-of-view that it will be able to see bursts from over 2/3 of the sky at one time. The observations made by GBM were verified by the Swift Telescope, another space telescope that can swiftly skew around to view a gamma ray burst.

NASA has a tradition of renaming spacecraft after a successful launch, and with GLAST they decided to wait until the “first light” images are released. Any guesses on what the new name will be?

Source: GLAST blog

July 25, 2008December 24, 2015 by Ian O'Neill

Astronomers Discover a Supernova/Gamma Ray Burst Hybrid

Spiral galaxy NGC 2770 with two supernovae SN 2007uy and SN 2008D. Credit: NASA

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Just when we thought we were beginning to understand what supernovae and gamma ray bursts were all about. Astronomers have just uncovered the true nature of what they thought was a regular supernova observed in January. At the time, it looked like a supernova emitting a 5-minute long burst of X-rays. But these X-rays were of a lower energy (known as “soft” X-rays) than expected leading some to believe this was a normal emission from a supernova explosion that was being observed during detonation (astronomers don’t usually get the chance to observe a star as it explodes and usually have to make do with analysing the supernova remnant). However, it is now believed this strange supernova event may have been emissions from a dying star at an intermediate mass, neither producing a supernova nor a gamma ray burst, but a combination of both…

Orbiting above Earth on January 9th 2008, the NASA/STFC/ASI Swift telescope caught a rare glimpse of what seemed to be a “normal” supernova at the precise moment of detonation. This observation was completely by luck, as Swift was already observing a supernova remnant (SN 2007uy) in spiral galaxy NGC 2770 that had exploded the previous year (90 million light-years away near the Lynx constellation). Then, as Swift was retrieving data from the SN 2007uy remnant, SN 2008D blasted a 5-minute long burst of X-rays in the same galaxy making this the first supernova to be directly observed.

However, looks can be deceiving. Researchers from a host of institutions including Italian National Institute for Astrophysics (INAF), the Max-Planck Institute for Astrophysics (MPA) and the European Southern Observatory (ESO) have analysed the supernova data thoroughly and at first agreed with the original assessment that it was indeed “normal.”

“What made this event very interesting is that the X-ray signal was very weak and ‘soft’, very different from a gamma-ray burst and more in line with what is expected from a normal supernova.” – Paolo Mazzali, INAF’s Padova Observatory/MPA, research leader.

Artist impression of the twin jets from a GRB. Credit: Dana Berry/SkyWorks Digital

However, astronomers at the Asiago Observatory in Northern Italy had designated the event as a Type 1c supernova, more commonly associated with long-period gamma-ray bursts. Type 1c supernovae are generated by hydrogen-poor progenitor stars with helium-rich outer layers prior to exploding at the end of their lives. But SN 2008D generated soft X-rays more associated with smaller stellar explosions. Therefore SN 2008D was probably produced by a star that was massive at birth (approximately 30 solar masses), rapidly using up its hydrogen fuel in its short life until it was only 8-10 solar masses. At this point it exploded, probably creating a remnant black hole. This chain of thought has led Paolo Mazzali and his team to think SN 2008D was produced by an object of a mass at the boundary of a normal supernova and gamma-ray burst.

“Since the masses and energies involved are smaller than in every known gamma-ray burst related supernova, we think that the collapse of the star gave rise to a weak jet, and that the presence of the Helium layer made it even more difficult for the jet to remain collimated, so that when it emerged from the stellar surface the [X-ray] signal was weak.” – Massimo Della Valle, co-investigator.

Researcher and co-author Stefano Valenti points out that this discovery indicates that all black hole-producing supernovae have the potential to be gamma-ray burst progenitors. “The scenario we propose implies that gamma-ray burst-like inner engine activity exists in all supernovae that form a black hole,” he added.

Source: ESO

March 21, 2008April 26, 2016 by Ian O'Neill

See that Record Breaking Gamma Ray Burst Go! (Video)

No sooner had NASA’s Swift X-Ray Telescope caught the record-breaking Gamma Ray Burst (GRB) in the actÂ on Wednesday (March 19th), the worlds telescopes swung toward the constellation of BoÃ¶tes to watch the afterglow of this massive explosion. One instrument in a Chile observatory was observing in Swift’s field of view at the time of the blast and has put together a short frame-by-frame video of the event. So if you missed this historic burst from 7.5 billion years ago (which you probably did!) you can watch it now…

Las Campanas Observatory is located high in the Chilean mountains and was used to observe the afterglow of the massive GRB observed at 2:12 am (EDT) last Wednesday. The Polish instrument called “Pi of the Sky”, a GRB detector array of cameras looking out for optical flashes (or transients) in the night sky. This ground-based instrument was lucky. Taking continuous shots in its wide field of view, the instrument’s automatic flash recognition algorithm detected the explosion two seconds before Swift’s Burst Alert Telescope (BAT). The Polish research group has released the chain of events in the form of an animation with frames 10 seconds apart (shown below). The blast decayed from the brightness of a 5 magnitude star to 11th magnitude over four minutes, allowing it to be seen by the naked eye when it was at its brightest.

One of the most significant results to come out of this multi-instrument observation of this event is that with 10 seconds of precision, the optical emission and gamma-ray emission from a GRB are simultaneous.

The “Pie in the Sky” project is unique in that it surveys the sky on the lookout for GRBs without depending on satellites. It does however use satellite indicators of GRB flashes to confirm its observations. By observing such a wide field of view, taking continuous 10s-interval shots of the sky, the instrument can observe the GRB in the very early stages of the blast.

GRBs are of massive interest to scientists. Generally, GRBs lasting for longer than two seconds are attributed to massive stars collapsing and forming black holes. Therefore observing the first two minutes of the blast and afterglow provides valuable information about black hole formation.

Source: Pie of the Sky

March 20, 2008December 26, 2015 by Ian O'Neill

Biggest Ever Cosmic Explosion Observed 7.5 Billion Light Years Away

A record-breaking gamma ray burst was observed yesterday (March 19th) by NASA’s Swift satellite. After red-shift observations were analysed, astronomers realized they were looking at an explosion half-way across the Universe, some 7.5 billion light years away. This means that the burst occurred 7.5 billion years ago, when the Universe was only half the age it is now. This shatters the record for the most distant object that can be seen with the naked eye…

Gamma ray bursts (GRBs) are the most powerful explosions observed in the Universe, and the most powerful explosions to occur since the Big Bang. A GRB is generated during the collapse of a massive star into a black hole or neutron star. The physics behind a GRB is highly complex, but the most accepted model is that as a massive star collapses to form a black hole, the in falling material is energetically converted into a blast of high energy radiation. It is thought the burst is highly collimated from the poles of the collapsing star. Any local matter downstream of the burst will be vaporized. This has led to the thought that historic terrestrial extinctions over the last hundreds of millions of years could be down to the Earth being irradiated by gamma radiation from such a blast within the Milky Way. But for now, all GRBs are observed outside our galaxy, out of harms way.

This record-breaking GRB was observed by the Swift observatory (launched into Earth orbit in 2004) which surveys the sky for GRBs. Using its Burst Alert Telescope (BAT), the initiation of an event can be relayed to Earth within 20 seconds. Once located, the spacecraft turns all its instruments toward the burst to measure the spectrum of light emitted from the afterglow. This observatory is being used to understand how GRBs are initiated and how the hot gas and dust surrounding the event evolves.

“This burst was a whopper; it blows away every gamma ray burst we’ve seen so far.” – Neil Gehrels, Swift principal investigator, NASA Goddard Space Flight Center, Greenbelt, Md.

This particular GRB was observed in the constellation of BoÃ¶tes at 2:12 a.m. (EDT), March 19th. Telescopes on the ground and in space quickly turned to BoÃ¶tes to analyse the afterglow of the burst. Later in the day, the Very Large Telescope in Chile and the Hobby-Eberly Telescope in Texas measured the burst’s redshift at 0.94. From this measure, scientists were able to pinpoint our distance from the explosion. This red shift corresponds to a distance of 7.5 billion light years, signifying that this huge GRB happened 7.5 billion years ago, over half the distance across the observable universe.

Source: NASA

March 3, 2008December 26, 2015 by Nancy Atkinson

Looking Down the Barrel of A Gamma Ray Burst

A team of astronomers from the University of Sydney in Australia have been keeping an eye on a binary star system called Wolf-Rayet 104, located in the constellation Sagittarius. Wolf-Rayet stars are hot, gargantuan, older stars that are losing their masses, and astronomers consider these stars as ticking bombs: they could go supernova at any time within the next few hundred thousand years. Thatâ€™s a relatively short fuse for astronomers. Images of this system from the Keck Telescope show an almost perfect spiral nebula formed by the two stars orbiting each other as they each blow off streams of gas. The way this system is spinning caught the eyes of these astronomers, who say Earth could be in the line of fire when the system blows.

Usually, a supernova explosion would be harmless at interstellar distances like the 8000 lightyears that this system lays from Earth, and it would just provide an impressive show for stargazers. But astronomers say the only way WR 104 could appear as an almost perfect spiral is if those of us on Earth were looking down the spin-axis of the system. Astronomer Peter Tuthill says that sometimes, supernovae focus their energy into a narrow beam of very destructive gamma-ray radiation along the axis of the system. A gamma-ray burst is a super-duper supernova that sometimes happens to massive stars, like the ones in WR 104.

As of now, no one can say for sure when the system will go supernova, or how massive and powerful the explosion might be. But the way these two stars are spinning about each other has astronomers thinking this system wonâ€™t provide just a run-of-the-mill explosion.

And an intensive gamma-ray burst at that distance could possibly be harmful to life on Earth.

But right now, this is all speculation, and more study on this system is needed before anyone needs to get worried. And this is all definitely very fascinating.

“I used to appreciate this spiral just for its beautiful form, but now I can’t help a twinge of feeling that it is uncannily like looking down a rifle barrel,” says Dr. Peter Tuthill.

With a sequence of 11 different images, the astronomers were able to portray how the spiral nebula of this system is rotating in a circle every 8 months.

Original News Source: University of Sydney Press Release

January 8, 2008December 26, 2015 by Fraser Cain

A Powerful Blast From the Distant Past

As sure as the Sun rises, you can expect that astronomers are going to beat their records. Today, we can wave goodbye to the record for the most distant short-duration gamma ray burst. Astronomers working with NASA have announced a newly discovered explosion that occurred 7.4 billion light years away. That’s nearly double the distance to the previous record holder.

Gamma ray bursts are the most powerful explosions in the Universe, and they come in two varieties: short and long. The long variety are thought to be when an extremely massive star collapses into a black hole. The short variety are different, and probably occur when two compact objects, like neutron stars collide together.

This newly announced burst is in that second variety; a short burst. As the two neutron stars collide, they rapidly collapse into a black hole, and release a tremendous amount of energy into two counterflowing beams.

GRB 070714B was the second burst detected on July 14th, 2007 by NASA’s Swift Satellite. Its energy signature matched the short burst variety, and the burst of energy lasted a mere 3 seconds. Astronomers scrambled to perform followup observations with ground-based telescopes, and were able to track the fading afterglow. This allowed them to identify the blast’s host galaxy.

With the host galaxy known, the astronomers were able to measure its distance, and confirm that yes, this is the most distant short-duration gamma ray burst ever seen; doubling the distance of the previous record holder.

There are a few mysteries outstanding. GRB 070714B seems to have 100 times as much energy as you would expect for a short duration gamma ray burst. Perhaps this is a merger between a neutron star and a black hole, or maybe the ejected beams happened to be pointing right at the Earth. That would make it seem more energetic, like when someone shines a flashlight directly at you.

Original Source: NASA News Release

June 26, 2007December 26, 2015 by Fraser Cain

Gamma Ray Observatory Will Launch in December

NASA has Hubble, Spitzer and Chandra to cover visible, ultraviolet, infrared and X-ray portions of the electromagnetic spectrum. The next wavelength to get its own space telescope is gamma rays. When NASA’s Gamma ray Large Area Telescope (GLAST) launches in December, there will be a powerful new observatory in space, capturing more gamma rays than any space observatory to date.

GLAST is currently living in a “clean room” at General Dynamics in Arizon. This is a special enclosed environment with very low levels of contaminants or environmental pollutants. It will remain in this clean room until it’s transfered to the launch pad later this year.

When GLAST finally makes it into orbit, it’ll be the most powerful and sensitive gamma ray observatory ever launched, gathering photons that can contain hundreds of billions of times more energy than we perceive with our eyes. These gamma rays are generated in the most extreme events in the Universe, such as the disks of gas swirling around black holes.

Unlike the other space-based observatories, GLAST doesn’t have a mirror to focus the photons; gamma rays don’t work that way. Instead, it’s got a large detector capable of detecting any gamma rays in 20% of the sky. It’ll orbit the Earth every 95 minutes, and image most of the sky 16 times a day. It can also be directed to stare in a specific direction to image an event, such as the afterglow from a gamma ray burst.

Original Source: NASA News Release

June 16, 2006March 29, 2013 by Fraser Cain

Integral Spots a Burst Out of the Corner of its Eye

Even it it’s not actually watching the spot in the sky where a gamma ray burst goes off, ESA’s Integral observatory can detect it. Engineers have developed a technique that allows the spacecraft see blasts out of the corner of its eye. Integral’s detector can sense radiation that passes through the side of its detector array. Scientists can then analyze this radiation to gather information on the gamma ray burst. The technique was first used to detect solar flares, and then fine tuned to work for gamma ray bursts.
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