The brightest gamma-ray burst ever seen in X-rays temporarily blinded Swift's X-ray Telescope on 21 June 2010. This image merges the X-rays (red to yellow) with the same view from Swift's Ultraviolet/Optical Telescope, which showed nothing extraordinary. (The image is 5 arcminutes across.) Credit: NASA/Swift/Stefan Immler
The brightest gamma-ray burst ever seen in X-rays temporarily blinded Swift's X-ray Telescope on 21 June 2010. This image merges the X-rays (red to yellow) with the same view from Swift's Ultraviolet/Optical Telescope, which showed nothing extraordinary. Credit: NASA/Swift/Stefan Immler

Gamma Ray Bursts

Swift Briefly Blinded by Mega X-ray Blast

14 Jul , 2010 by

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A record-breaking gamma ray burst from beyond the Milky Way temporarily blinded the X-ray eye on NASA’s Swift space observatory on June 21, 2010. The X-rays traveled through space for 5-billion years before slamming into and overwhelming the space-based telescope. “This gamma-ray burst is by far the brightest light source ever seen in X-ray wavelengths at cosmological distances,” said David Burrows, senior scientist and professor of astronomy and astrophysics at Penn State University and the lead scientist for Swift’s X-ray Telescope (XRT).

A gamma-ray burst is a violent eruption of energy from the explosion of a massive star morphing into a new black hole. This mega burst, named GRB 100621A, is the brightest X-ray source that Swift has detected since the observatory began X-ray observation in early 2005.

Although Swift satellite was designed specifically to study gamma-ray bursts, the instrument was not designed to handle an X-ray blast this bright. “The intensity of these X-rays was unexpected and unprecedented” said Neil Gehrels, Swift’s principal investigator at NASA’s Goddard Space Flight Center. “Just when we were beginning to think that we had seen everything that gamma-ray bursts could throw at us, this burst came along to challenge our assumptions about how powerful their X-ray emissions can be.”.

For more information on this burst, see this press release from Penn State’s Eberly College of Science.

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By  -        
Nancy Atkinson is currently Universe Today's Contributing Editor. Previously she served as UT's Senior Editor and lead writer, and has worked with Astronomy Cast and 365 Days of Astronomy. Nancy is also a NASA/JPL Solar System Ambassador.



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Don Alexander
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Don Alexander
July 14, 2010 5:02 PM

Please also check out this article:

http://geeked.gsfc.nasa.gov/?p=1417

It mentions:

“And he saw something very puzzling: For one event, GRB 100621A, the record of its earliest X-ray emission was missing. He´d also received an email from another astronomer who had also noticed the gap.”

That would have been me. razz

Of course, I’m not mentioned in the press release… >_>

Matt Mazur
Member
Matt Mazur
July 14, 2010 7:25 PM

hi Don, I’m curious if you know what time of day the GRB was first detected? thanks. smile

Aqua4U
Member
July 14, 2010 9:08 PM

Dang near inconceivable amount of energy. In a word – WOW! Does this indicate a polar axis/jet(?) was pointed directly at us?

Don Alexander
Member
Don Alexander
July 15, 2010 2:13 AM

@Matt: It triggered swift at 03:03:32 Universal Time. Otherwise, I don’t get your question, the time-of-day of course depends on where you are on Earth… 3 UT means it was midnight over the western Atlantic.

@Aqua: Yes, it was probably quite close to the polar axis, but not exactly on it. The two main reasons for the extreme brightness are a) The burst was quite nearby and b) it was rather long and Swift was on target very rapidly, so it caught it still during the main phase of the prompt emission.

Don Alexander
Member
Don Alexander
July 15, 2010 4:09 AM

Addendum:

From the figure caption:

“with the same view from Swift’s Ultraviolet/Optical Telescope, which showed nothing extraordinary.”

This is actually completely wrong, but it’s wrong in the press release itself too.

Bright X-ray afterglows typically imply bright optical afterglows too, but in this case, you see NOTHING in the UV/optical!!

The reason is that the GRB afterglow was strongly extinguished by dust (in the GRB host galaxy), shortly afterward, the GROND detector on the 2.2m telescope in La Silla, Chile, observed the extremely red afterglow – basically invisible in the optical but very bright in the near infrared.

Jon Hanford
Member
Jon Hanford
July 15, 2010 4:28 AM

I’ve seen a few reports that indicate that this GRB may be highly obscured within its host galaxy. GCN 10876 noted:

“Preliminary inspection of the spectrum [with VLT/X-shooter] reveals emission features which we interpret as due to [O II] 3727, Hbeta and the [O III] doublet from the underlying host galaxy, at a common redshift z = 0.542. The [O II] line is very weak. This, together with the low redshift and the optically faint and red afterglow supports high extinction internal to the host (Updike et al., GCN 10874).”

Future observations should give us more information on this possible scenario.

Jon Hanford
Member
Jon Hanford
July 15, 2010 4:43 AM

@Don: I posted about the same time and missed your addendum mentioning the La Silla observations (Updike et al., GCN 10874).

“with the same view from Swift’s Ultraviolet/Optical Telescope, which showed nothing extraordinary.”

Maybe they should have left out “extraordinary” grin

BTW, what are the approximate limiting magnitudes for the UVOT instruments?

Don Alexander
Member
Don Alexander
July 15, 2010 5:21 AM

@Jon: Always depends on the exposure time… Extremely long exposures (think, a complete day) in White (filterless) can reach 25th magnitude. The UV filters as well as u and b can reach 23 or so, and maybe 22 in v, which is not so sensitive.

And one little correction: In longer exposures, Swift actually does detect a source in almost all filters, but this is the bright host galaxy (Oates & Ukwatta, GCN 10878). Swift never detected the UV/optical afterglow itself.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
July 15, 2010 5:31 AM

a) The burst was quite nearby

Oy vey, half across the visible universe and “nearby”? (Since “on target very rapidly” indicates we aren’t discussing angular distances here.)

I must get me one of those playgrounds of astronomers, they have too much fun paring the universe down to size!

Don Alexander
Member
Don Alexander
July 15, 2010 5:42 AM

@Torbjorn: For us GRB-people, a redshift of z = 0.542 is very nearby, yes. Swift rahter rarely detects bright GRBs at redshifts under 1… After all, if it were not extinguished so strongly, we would be supernova-hunting now…

Also, it’s quite a bit less than half the age of the universe.

Olaf
Member
Olaf
July 15, 2010 6:26 AM

@Don Alexander
Thanks for the additional info. It is great to hear more detailed stuff.

SteveZodiac
Member
SteveZodiac
July 15, 2010 6:46 AM

Does the data from this GRB throw any more light on the theories of their origins e.g. Hypernovae?

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
July 15, 2010 7:12 AM

@ Don:

Ah yes, I forgot the applicable hyperbolic geometry. Should make me abstain from hyperbole, shouldn’t it?

“quite a bit” Yes, very roughly. But then again, what is an order of magnitude between friends? grin

Aodhhan
Member
Aodhhan
July 15, 2010 8:25 AM

Nice job Don, thanks!

I know the initial thought is this was a collapsing star, but as luminous and far away this was, I’m wondering if it wasn’t from a merger of some sort; possibly with a black hole.

Is it being considered a short or long burst? Were there any postbursts?

jimhenson
Guest
jimhenson
July 15, 2010 5:40 PM
Earth had 5 major mass extinctions, the Ordovician period killed all land and shallow marine life, but not deep marine life. Iridium and rare earth earth indicates meteroids, comets, and rule out a supernova cause for the dinosaurs. A supernova remnant is unable to find after several tens of thousands of years. Melott, Lipps say two or more times every billion years a supernova within 1,000 light years will cause extinctions on earth. Every 50 years a supernova happens in the milky way but most are too distant and not aligned. The ozone layer of the earth would go early and ocean water shields with depth, which is why the Ordovician has been theorized as a supernova extinction.… Read more »
Matt Mazur
Member
Matt Mazur
July 15, 2010 10:52 AM

I wonder if we were oriented down the axis of a directed blast, or if this was a spherically symmetric explosion. If the latter, surely it would have “sterilized” the entire host galaxy? Sounds like a serious dose of X-Rays at close range. Is there evidence for Earth extinctions being caused by such? Maybe it’s not always asteroids (or oil leaks?) that cause mass extinctions down here on Earth.

Lawrence B. Crowell
Member
Lawrence B. Crowell
July 15, 2010 12:50 PM
For z = 0.542 the distance can be computed for v = Hd. Since these distant objects are on comoving frames being dragged by the expansion of space we can observe objects for z > 1, where z = 1 corresponds to c = Hd_h. d_h = sqrt{3/Lambda} for Lambda the cosmological constant. This distance is about 12 billion light years. So a rough estimate based on z gives d/d_h ~ 0.542, or the distance to this GRB is ~ 6.5 billion light years out. To compute the time this happened the linear relationship between distance (or FLRW scale factor a) and time is not entirely right. The scale factor grows exponentially with time a ~ exp(sqrt{Lambda/3}t} and… Read more »
Don Alexander
Member
Don Alexander
July 15, 2010 6:01 PM
So many questions… Let’s see what I can answer. @SteveZodiac: Hm, maybe a bit, yes. The highly extinguished afterglow implies the GRB occured in a region with high dust content. Now, this MAY just be a projection effect (say, it’s on the other side of the host galaxy), but more likely is that the dust is local, implying a molecular cloud and thus high-mass star formation. @Aodhhan: Definitely a long burst – here is the Swift BAT light curve: [url[/url] And actually, it is neither very distant nor very energetic, as GRBs go. there have been ones that are 100 times more energetic. There was no further “action” after what you see here. Collapses of massive stars leading… Read more »
Don Alexander
Member
Don Alexander
July 15, 2010 6:05 PM
So many questions… Let’s see what I can answer. @SteveZodiac: Hm, maybe a bit, yes. The highly extinguished afterglow implies the GRB occured in a region with high dust content. Now, this MAY just be a projection effect (say, it’s on the other side of the host galaxy), but more likely is that the dust is local, implying a molecular cloud and thus high-mass star formation. @Aodhhan: Definitely a long burst – here is the Swift BAT light curve: And actually, it is neither very distant nor very energetic, as GRBs go. there have been ones that are 100 times more energetic. There was no further “action” after what you see here. Collapses of massive stars leading to… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
July 16, 2010 4:48 AM

I certainly would not be healthy for living systems if a supernova occurs nearby. It is plausible that our solar system has orbited close to dangerous astrophysical objects and these have played a role with Earth history.

LC

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