Furthest Gamma Ray Burst Seen

[Fraser]

SUMMARY: Just a few hundred millions years after the Big Bang, a massive star exhausted its fuel, collapsed as a black hole, and exploded as a gamma ray burst. The radiation from this catastrophic event has only now reached Earth, and astronomers are using it to peer back to the earliest moments of the Universe. The burst, named GRB 050904, was observed by NASA's Swift satellite on September 4, 2005. One unusual thing about this burst is that it lasted for 500 seconds - most are over in a fraction of that time.

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What do you think about this story? post your comments below.

[mknorr]

One thing confounds me. When we look as far as we can, we look back around 13 billion years. That means it took the stuff that makes up our solar system 13 billion years to get here. So if this star exploded a few 100 million years after the big bang, how did we get here so much quicker that the light from that explosion? Nothing travels faster than light they tell me.

[dvb]

Nothing travels faster than light they tell me.

The expansion of space between two objects is known to exceed the speed of light. The reason that we're not seeing this GRB until now, is because it's taken the light this long to catch up to the expansion of space. The following link gives you a more detailed explanation than I can.

Universe Measured: We're 156 Billion Light-years Wide!

[antoniseb]

One very important part of this story was the statement that the GRB was seen time dilated by roughly a factor of six. I am very curious to know more details about how they determined this. If this is not just supposition, this is a major obstacle for most alternative theories of the universe. I'm starting a thread in the Against The Mainstream section to discuss this.

Here: http://www.bautforum.com/showthread....777#post698777

[Fr. Wayne]

I can't respond to questions above, but would like to ask if an unconfirmed blog has any relationship to this gamma wave.
[[Discovered April 6 by NASA's Chandra X-ray Observatory, the swirling,
10 million-mile- wide cosmic dust cloud has been likened to an
"acid nebula" and is hurtling toward us at close to the speed of light
-- making its estimated time of arrival 9:15 a.m. EDT on June 1, 2014."
(A BLOG REPORT SEPT 25 ENTITLED "CHAOS CLOUD"... no confirmation. )]]

[antoniseb]

hurtling toward us at close to the speed of light
-- making its estimated time of arrival 9:15 a.m. EDT on June 1, 2014."

Hi Wayne, you know enough about astronomy to know this is false (a hoax). Just for starters, it talks about something 10 million miles across moving at near the speed of light that we can see 8 lightyears away, but know the arrival time to the minute, certain that it is headed right at us, with no tangential velocity?

This has nothing to do with the distant GRB.

[dvb]

Also don't forget that most nebulae that we know about are lightyears across. If it were the orion nebula at only 8ly distance, you wouldn't be able to miss it. As it currently stands, the orion nebula is between 200-600ly away, and 8-15ly across, and is visible to the naked eye. Nebulae tend to expand outwards from a star that went supernova, not hurtle in any specific direction. This is definately OT.

[shaithis]

Something just occurred to me while I was reading this article. If all early stars were pure hydrogen, then all of them had to be supergiants or hypergiants. This would lead me to believe that all of them, when they died, because none would still be burning now, became either neutron stars or black holes. There really isn't an alternative for them is there? I suppose that would explain why all well developed galaxies seem to have supermassive black holes with millions of solar masses. Further, Has it occurred to anyone that this 'dark matter' that everyone is so convinced must be made out of some as yet undisovered material could possibly be an interwoven bed of neutron stars and other burnouts throughout the cosmos? I mean if there are no nearby stars to illuminate them, we'd never see them.

[antoniseb]

...Has it occurred to anyone that this 'dark matter' that everyone is so convinced must be made out of some as yet undisovered material could possibly be an interwoven bed of neutron stars and other burnouts throughout the cosmos? ...

This has occurred to people in their search for missing mass. The OGLE and related surveys have turned up one or more of these objects, and so we have a rough sense of the density of these things in the galaxy. The total mass of these things is enough to be a significant fraction of the "missing mass" of normal matter, but is not more than a drop in the bucket of the needed mass for cold dark matter seen in galactic clusters.

[shaithis]

How long does it take for a white dwarf to totally cool off and what happens to it then? When a star goes nova, where do its planets go? How many old cooled off white dwarfs get mistaken for gas giants? Would we know the difference? What is the density of lost planets? How many nebulas collapse into objects that are not stars? What percentage of a nebula that collapses into stars has material that collapsed into invisible objects?

[Don Alexander]

Hello, everyone, first I thought, what's this old news, but of course, the Nature articles are out!!

Okay, a bunch of answers.

@antoniseb: That's very easy to answer: Redshift z = 6.295. Dilation factor = z + 1 = 7.295. That's all. Thus, the total duration of the burst in the source frame was about 70 seconds, which is a bit longer than typical, but nothing special.

@dvb: Whoops! The Orion Nebula is about 1500 ly away and about 50 ly in diameter. It's a star-forming region and has nothing to do (yet!) with supernovae remnants.

@shaithis, part 1: You are right, the so-called "Population III stars" in the early univverse consisted only of hydrogen and helium (don't forget that, it's 1/10th of the primordial atoms and 1/4th of the mass!!!) and thus became very massive. Today, with more massive elements ("metals"), stars have more channels for "cooling" - they are quite opaque. If a newborn star becomes to massive, it blasts of its outer layers via radiation pressure, limiting the size to which it can grow. Pop III stars didn't have this possibility, they possibly grew til they blew.

For such massive stars, there's a further destruction channel, a so-called "pair-production supernova". I'm not sure how this works, but I think it's basically this: When the star is massive enough (something like 200 solar masses or more), the pressure and temperature at the center become so high that the emitted gamma-rays can form electron-positron pairs. This decreases the radiation pressure and causes the star's core to collapse. But these explosions are supposed to leave no remnants, like Type Ia SN.

Supermassive black holes at galactic centers are probably originally formed via the collapse of "dark matter cusps", primordial concentrations of dark matter - the galaxies actually formed around them. Stellar accretion is too slow, supermassive black holes have been discovered at very high redshifts (quasars).

Concerning compact objects (NS, BH) as dark matter. Sure, part of it is. But as antoniseb points out, it's only a smidgen. The thing is, observations of the CMB, primordial deuterium abundance and other markers give tight limits on the amount of baryonic (protons, neutrons, electrons) matter in the universe, and it's much less than the dark matter that's needed. Only black holes have the possibility of non-baryonic origin, neutron stars were once stars, that's normal baryonic matter. And dark matter mapping via gravitational lenses or ellipticity measurements point to uniform halos of dark matter. These can't be made up of many small black holes, as the search for such objects around our galaxy has only yielded few candidates.

@shaithis, part 2:
A) White dwarfs: Even the oldest (in globular clusters) are still cooling. They turn into black dwarfs, cold, lifeless cinders with very high surface gravity. Basically gigantic crystals.
B) Nova? Erm... Novae are thermonuclear explosions on the surfaces of white dwarfs that accrete matter from companion stars. Perhaps you mean supernovae? It is unsure if such massive stars can have planets, as the surroundings of young massive stars are very hostile to close-in disks and thus planet formation. But let's assume. I'd say (am not sure, though) that the pressure of the expanding shell is not enough to actually destroy the planet. There will be orbital changes, as the mass of the star changes drastically, it basically blows most of its matter into space. But in the end, most planets will probably remain to orbit a neutron star. (There have been planets discovered around neutron stars. It's unsure if they are from before the explosion, captured, or even formed out of the SN debris).
C) WD as gas giants? None, I'd say. Still too hot, completely different spectrum.
E) Yes. Spectrum. Surface gravity. Zeeman splitting.
F) Huh? Lost how. Supernova? Gravity slingshot?
G) I take it you mean brown dwarfs. Lots. Lots and lots. More than stars.
H) 100%. Any star forming region preferentially forms brown dwarfs by numbers (not by mass). But they are not really invisible, of course. No star-forming region immediately produces black holes or neutron stars.

So, shaithis, that makes 100 bucks.

Don Alexander
The 1337 GRB Guy ;-}

TLS Tautenburg, Germany

[antoniseb]

...@antoniseb: That's very easy to answer: Redshift z = 6.295. Dilation factor = z + 1 = 7.295. That's all. Thus, the total duration of the burst in the source frame was about 70 seconds, which is a bit longer than typical, but nothing special...

Thanks Don Alexander. BTW, I was aware of how to compute time dilation. My point was that we don't know how they concluded that they were seeing time dilation. Since time dilation associated with cosmological red shift is a problem for some of the alternative theories, it seemed worth exploring just how certain the scientists making this observation were that what they were seeing is really time dilation...

Also, it occurs to me that most of the GRBs we've been seeing are from before z=1, so 500 vs. 70 seconds is not a completely fair comparison.

Do you have a pointer to more information about this particular burst?

[shaithis]

Don Alexander,

Thanks for the response. A couple more questions.

>>Supermassive black holes at galactic centers are probably originally formed via the collapse of "dark matter cusps", primordial concentrations of dark matter - the galaxies actually formed around them. Stellar accretion is too slow, supermassive black holes have been discovered at very high redshifts (quasars).<<
If the very early universe were much smaller than today's, and I mean in the first couple million years, long enough for the first hypergiants to die, then I would imagine that since the total amount of matter in the universe is the same that the density of the universe was much higher. If there is a nursery of 400 hypergiants that all popped and formed neutron stars and black holes, stellar accretion is much faster in such an environment. Especially after having seen current models for BH mergers.

B) when I say nova, I mean the death throes of a star like sol. When its outer shell is blown off, it is not with enough force to destroy, say Jupiter. Jupiter will continue to be a planet. One day it might either wander away from sol (especially if the mass of sol drops significantly after 'nova') or be pulled away by a passing star. There will be a high number of these I think considering Neptune and Uranus. Plus, some of the first planets ever made very likely still exist. Planets do not blow up, but they may be swallowed (type 1A SN).

A hundred bucks?
I musta missed the joke, being new and all.

[dvb]

@dvb: Whoops! The Orion Nebula is about 1500 ly away and about 50 ly in diameter. It's a star-forming region and has nothing to do (yet!) with supernovae remnants.

My mistake don. Thanks for the clarification. I should double check my figures next time I google them.

[Mortac]

A hundred bucks?
I musta missed the joke, being new and all.

With all your questions, it was way more than 2 cents.

[Don Alexander]

@antoniseb:

You're right. It was simply assumed that in the standard model, there's time dilation proportional to redshift. GRB 050904's GR light curve was characterized by spread-out, faint emission. Divide it by 7, it looks more like a normal GRB. Many recent high-redshift (z ~ 4) events have been found, and most show this stretched emission. But there are other cases, like GRB 060206, which was at z = 4 and only 7 seconds long making it less than two seconds in the source frame, on the extreme short end of the long GRB duration distribution. On the other hand, a GRB I'm working on, GRB 060124, was over 240 seconds long in the source frame.
But you're right concerning that the typical GRB length has been derived without dilation correction. And there's no way to just look at the GR light curve and detect a time dialtion and thus a precise redshift. Okay, there's stuff like the lag-luminosity relation, but this is very rough.

More information... Hm.

Here's a news article from Enrico Ramirez-Ruiz from yesterdays Nature:
http://www.nature.com/nature/journal...df/440154a.pdf
(Seems the download is free of charge and accesable to all?)

Otherwise, I can only offer some real papers on the burst, but these are, of course, technical in nature.

http://arxiv.org/abs/astro-ph/0509640 (Watson et al. on the X-ray light curve)
http://arxiv.org/abs/astro-ph/0510381 (Klotz et al. on a prompt optical flash)
http://arxiv.org/abs/astro-ph/0512154 (Totani et al. in detail about the Subaru spectrum - fantastic paper!)
http://arxiv.org/abs/astro-ph/0509766 (Tagliaferri et al. on the optical/NIR light curve)
http://arxiv.org/abs/astro-ph/0512052 (Kawai et al. on the Subaru spectrum, from Nature)
http://arxiv.org/abs/astro-ph/0509660 (Haislip et al. on discovery of the optical/NIR afterglow, from Nature)
http://arxiv.org/abs/astro-ph/0509737v3 (Cusumano et al. on Swift observations; v4 is the Nature version, which has been drastically shortened)

@shaithis:

First, the first stars didn't form until several hundred million years after the big bang.
Second, yes, the density was higher, but only on a cosmological scale. On small (galactic) scales, gravity dominates, and the stellar density was comparable to denser star clusters today. But the (proto-)galaxy density was higher, leading to many collisions which produced starbursts.

The end of the sun will be very gentle, it will transform into a planetry nebula and leave a white dwarf. While the solar wind will become much denser and faster in the final mass ejection phase, this will take many thousands of years and is not an explosive event. Of course, this means you're right on the "survivability", but the term nova is wrong.
When it comes to the long-term chances of the Solar System, I can recommend Adams and McLaughlin's "The Five Ages of the Universe" (the most depressing book I've ever read... ). The outer gas giants and maybe even Mars and Earth should survive the red giant phase of the sun, which is much more dangerous. Neptune and Uranus were formed with the rest of the Solar System!
So, yes, a lot of old planets should still be around somewhere. They only explode if they are in the way of a hyperspace bypass. (And what does this have to do with Type IA SN??)

So that's my fifty bucks worth for today (we professionals have steep hourly rates! )

Don Alexander

[antoniseb]

Thanks Don Alexander! These look like great resources.

[Fr. Wayne]

Thanks for clearing up an old note I kept. I'm sure it was a hoax now. Thanks Antoniseb and dvb.

[shaithis]

I have read in several different articles that Uranus and Neptune may not be original members of the sol system, but were stolen from a nearby star early in sol's formation. This is suggested because of the compostition of the two planets, along with several various anomolies in their orbits, especially Uranus' extreme axial tilt and backwards rotation.

As far as what I meant by the early stars, they were all hypergiants or supergiants. So that means to me that they all became either neutron stars or black holes a few million years later, at best a few hundred million years later. Even if there were no stars in the first hundred million years, we still have neutron stars and black holes before the 1 billion year mark, and everywhere. Now, the stars that continued to form during and after that period were also still almost all hydrogen and helium. Heavy metals are unheard of at this point. In fact, up to the point where smaller stars are able to form, I am under the assumtion that all stars were becoming either neutron stars of black holes. If I have a cluster of 10,000 stars, and they all become ns or bh after 100,000,000 years, then I don't have a cluster of them, I have a supermassive black hole. Evidence suggests that SMBH were around early in the universe, even before the billion year mark.
((http://www.universetoday.com/am/publ...early_on.html))


As far as the reference to a 1A SN, it happens when a white dwarf accretes material off of another object and reignites nuclear fusion in its core. This detonates the dwarf into a type 1A SN. So in the context of my post, I was referring to Jupiter eventually spiralling into sol's corpse and thus destroying both. What I was trying to describe was the relatively high population of rogue planets that would have to be there just on random perturbations of systems by each other not to mention the untold number of planet sized objects created in stellar nurseries in spots where there just isn't enough material to make a star, like in the glare of a baby hypergiant.


That's a high hourly rate. Unfortunately, there are processing fees, import tariffs, local taxes and union dues, incentive bonuses and everybody has to get their 'cut', so sadly you still only get the flat $.02. =D

[antoniseb]

I have read in several different articles that Uranus and Neptune may not be original members of the sol system, but were stolen from a nearby star early in sol's formation.

Where did you read those articles? Most mainstream thought is that Uranus and Neptune were certain formed from the same disk as Earth, Jupiter, Saturn, and the Kuiper belt. It is possible that a small number of comets were stolen from elsewhere, but even then, not many.

Concerning your thought that all early stars had to be short-lived hypergiants, I think that a little thinking will tell you that red dwarfs were also formed in this period, and are still main sequence today, though possibly a little more massive for their luminosity than their higher-metalicity younger cousins.

[Don Alexander]

@shaithis:

A) Uranus and Neptune, with an extremely high probability, formed together with the rest of the Solar System. Uranus's tilt is probably due to a massive impact in the early days of the System. If you think this little "evidence" makes them candidates for extrasolar origins, then what about Venus? That planet spins BACKWARD!

The chances of the sun capturing two planets that then land on almost circular orbits almost perfectly in the ecliptic plane is negligible. A captured planet would probably be on an extremely exentric orbit taking it far "above" or "below" the system.

B) While you seem to be correct in stating that the very first stars were all massive, even a small amount of metals leads to the formation of low-mass stars. If all early stars were destined to become SN, there would be no Globular Clusters today!! Furthermore, each SN immediately creates loads of "metals", as the fusion all the way to iron is the route to the SN itself. These early massive starburst rapidly created pockets of metal enrichment within the primordial gas.

Check out:

http://arxiv.org/abs/astro-ph/0310622

Here's something on the first black holes that form without stars:

http://arxiv.org/abs/astro-ph/0212400

For a great review on the first stars, check out:

http://arxiv.org/abs/astro-ph/0311019

C) I know what a Type IA SN is. Your explanation is basically correct, but misses some important points. White dwarfs are formed of so-called "degenerate matter", a high density crystal lattice that is kept from collpasing by the pressure of the electron "gas". as the rules of quantum mechanics only allow the electrons to have certain states (Pauli principle, creating a Fermi gas), they can not be compressed further. Chadrasekhar showed that this only alows stability up to about 1.4 solar masses, the Chadrasekhar mass - in Chandrasekhar simple model, the radius of the star reaches 0 at this mass and would become a black hole. (It's really the case that more massive white dwarfs are actually smaller than less massive ones) What actually happens is that upon reaching the Chandrasekhar mass, the temeprature and pressure reach such values that fusion initiates in fully degenerate carbon (normally, degenerate matter does not fuse, it first leaves the degenerate state), creating a "carbon flash". As there is no outer envelope to break the expanding shockwave (as in the multiple helium flashes of asymptotic giant branch stars), the white dwarf tears itself apart in a supernova.

Now, you mention accretion of planets to trigger Type IA SN. Basically, this is possible, but it should be exceedingly rare. Type IA SN happen in binary systems. When the less massive star reaches its red giant phase, it expands, fills its Roche lobe and matter starts spilling over onto the white dwarf. This mass accretion rate is much higher than what a single planet would make. When enough matter has accumulated on the surface of the WD, hydrogen fusion initiates, creating a classical nova (yes, the nova prevents the WD from going supernova too early, as it decreases the mass slightly again).

In the specific case of the Sun and Jupiter: The Sun will have about 0.6 Solar masses as a white dwarf, and Jupiter has 1/1000th of a Solar masses. So no chance of reaching the Chandrasekhar mass... Even in a globular cluster, the number of rogue planets will be, by mass, quite small, collisions between them and white dwarfs will be rare, so this is not a realistic channel for Type IA SN.

Levan et al. recently proposed a model of two white dwarfs merging, creating an object that is super-Chandrasekhar, which could then, due to high angular momentum from the merger, collapse into a neutron star instead of being destroyed completely. This neutron star would be a magnetar, thus creating such an object in a globular cluster, which can reside far from the stellar nurseries that normally create magnetars. The universe is complicated.

And of course my hourly rate is high!! By now, I have earned 0.06$ off you!

[Fr. Wayne]

D.A.? Could you tell me for 0.10$ the answer to a lazy man's stupid off-topic question? What are the probablilities of the Sirius binary going nova in this millenium? Please limit answer to 2007 Space Appropriations Budget Expenditures as stated above. Thanks.

[Don Alexander]

0

[Don Alexander]

Because the orbital seperation of the stars is much too high and Sirius is still on the main sequence. No mass transfer can take place.

As far as I know, Sirius B will never explode as a supernova.

[Don Alexander]

The Swift Team has submitted its paper to Nature and placed it on astro-ph:

http://arxiv.org/pdf/astro-ph/0603279

I can wholeheartedly recommend anyone who is interested in this event to read this paper. It is not too technical in nature (slight pun intended) and both the presented data and the conclusions are superb.

Let's hope our own Nature paper turns out this well...

[Fr. Wayne]

Excellent data including radiation pressure from plasma and WO WO stars to boot.