Cosmic Explosions: Powered by "Magnetism" or "Electricity"?

by mgmirkin | December 11, 2009 at 02:21 pm

280 views | 38 Recommendations | 9 comments

A recent observation by the Liverpool Telescope on the Canary Island of La Palma in coordination with NASA's Swift satellite has indicated the first detection of magnetic fields in the afterglow of a Gamma Ray Burst. This may be a significant discovery.

On January 2, 2009, NASA's Swift satellite observed a gamma ray burst (GRB) erupting and quickly alerted telescope operators around the world.

...the robotic Liverpool Telescope on the Canary Island of La Palma automatically began observing [the gamma ray burst].

Gamma rays are, to over simplify, high frequency, high energy light waves (occurring largely over the same portion of the EM spectrum as x-rays). Since they are light waves and light is an electromagnetic wave, their behavior can be affected by electric and magnetic fields. Polarized light is often a sign that the light has been influenced by a non-trivial magnetic field.

Indeed, that is the conclusion reached by astronomers analyzing the data gathered by the Liverpool Telescope.

The telescope was fitted with a filter that detects polarized light, or light that is electrically and magnetically aligned in a certain direction. Indeed, the observatory found polarized light in the gamma ray burst signature, which told the researchers that the light originated in a magnetic field.

"This is a first indication that magnetic fields are very important [in GRBs]," Steele told SPACE.com. "I think this is a good step forward to understanding the energetics in the jet and the role of magnetic fields."

New observations help us to refine existing models and sometimes even to overturn them. This makes many scientific "firsts" quite exciting. This observation may be one such opportunity to test, refine or overturn existing models.

The astronomers have been quite clear that the results indicate the light polarization due to the presence of large-scale magnetic fields.

The model that best fits the observations ... suggests large-scale magnetic fields present throughout the relativistic outflow, originating from the start inside the "central engine" driving the explosion and accelerating and collimating the jet.

But, what does it all mean?

This appears to imply that magnetic fields are present and non-trivial in the production of GRBs. But, where do the magnetic fields come from? Is it possible that they are dynamically generated in the same process that generates the gamma rays? That is to say, could this be tentative proof that GRBs are inherently electrical in nature?

Electric current produces a magnetic field.

The same laws of physics hold true in space as hold true here on Earth. Moreover:

Electric current can be directly measured with a galvanometer, but this method involves breaking the circuit, which is sometimes inconvenient. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current.

Is that what astronomers and their sophisticated technological toys have just done: measured the current by detecting the magnetic fields associated with it?

Quite possibly!

A freely available paper from 2005 in the Chinese Journal of Astronomy and Astrophysics may provide one possible explanation: a pinch discharge.

Large-voltage, high-temperature plasma columns produced by pinch discharge can generate γ-ray [gamma ray] flashes with energy spectra and spectral evolution consistent with what are observed in γ-ray [gamma ray] bursts (GRBs), and the inverse Compton scattering (ICS) during the discharge process can produce high linear polarization. Our calculation indicates that the observed polarization depends on the angle between the line-of-sight to the GRB and the direction of the pinch discharge, but only weakly depends on observed γ-ray [gamma ray] energy.

What is a pinch discharge (AKA, a Bennett pinch, magnetic pinch, electromagnetic pinch, z-pinch or the pinch effect), you ask? Simply put, it is an electric discharge through a medium such a metal or plasma which generates a significant magnetic field that acts to compress and collimate the current flow (making it thread- or jet-like, similar to lightning or a spark to a door knob from static electricity). Sound familiar?

The model that best fits the observations ... suggests large-scale magnetic fields present throughout the relativistic outflow, originating from the start inside the "central engine" driving the explosion and accelerating and collimating the jet.

Is it possible, then, that GRBs are simply the product of large-scale electrical discharges in space? If so, GRBs may well be observations of synchrotron radiation generated by such discharges.

Synchrotron radiation is electromagnetic radiation ... generated by the acceleration of ultrarelativistic (i.e., moving near the speed of light) charged particles through magnetic fields ... The radiation produced may range over the entire electromagnetic spectrum, from radio waves to infrared light, visible light, ultraviolet light, X-rays, and gamma rays. It is distinguished by its characteristic polarization and spectrum.

In fact, the author (Maxim Lyutikov from the Department of Physics at Purdue University) of the current paper on magnetic fields in the afterglow of a GRB had previously speculated about the applicability of synchrotron radiation to observation of GRBs in another paper.

The best way to produce polarization in the range 10% ≤ Π ≤ 60% is through synchrotron emission in large scale magnetic fields (Lyutikov et al., 2003).

So, it would seem this observational result is in keeping with Lyutikov's prior thoughts on the subject of synchrotron radiation and seems to be in keeping with the earlier paper on pinch discharges.

So, are we on the verge of proving that GRBs are an inherently electrical phenomenon? Essentially a large spark in space?

Hopefully, Lyutikov or others will come across the paper on the pinch discharge model of GRBs and compare notes with its authors.

A NASA article on the subject summarizes nicely:

"These very interesting observations [from Swift and the Liverpool Telescope] raise the possibility that gamma-ray bursts are not fireballs as usually presumed but are powered and collimated by an organized electromagnetic field," said Roger Blandford, Director of the Kavli Institute of Particle Astrophysics and Cosmology at Stanford University, California, commenting on the result's importance. "It will be very interesting to see if there are similarities in observations of other kinds of cosmic jets."

With our increasing technological wizardry and ability to peer deeper into the mysteries of the universe, we live in interesting times.

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Amy Judd

at 16:51 on December 11th, 2009

This is interesting, I'm just not sure I understand how it will be siginficant to us, or could be significant to us?

mgmirkin

at 16:59 on December 11th, 2009

Well, significant from the point of view of trying to understand how and why GRBs occur, what the actual physical process behind it is. Maybe that leads to understanding of other processes... Sometimes new discoveries take us in unexpected new directions. I just think it's interesting that the Chinese paper implies it might be something as simple as a plasma / electrical discharge (as opposed to some heinously difficult to understand phenomenon)...

Plasma discharges we can study in the lab in low pressure discharge tubes or with the Z-machine.

Black holes, neutron stars and other exotic hypotheticals? Not so much...

Uwe Paschen

at 16:59 on December 11th, 2009

So far it is an observation and a hypothesis based on models that may fit this observation. We shall see what further research may come up with.

However, it is rather interesting and fascinating as well. It may give us some mans for space technology ad propulsion i the future aside from a better understanding of our universe at large.

mgmirkin

at 17:00 on December 11th, 2009

Yep, all just interesting speculation at this point. :)

Will be interesting to see where things go over the next few years...

Tomitheos Linardos

at 21:35 on December 11th, 2009

interesting scientific theories, if the energy is electric or magnetic in nature then could the gamma ray bursts be residual energy left behind from an impact collision with a mirror mass?

Mirror Mass Particles

hidflect

at 19:57 on December 11th, 2009

I side with a group that believe the explanation for our universe's structure is far simpler than scientists currently allow for and this information is being actively suppressed by the scientific community. I've lost a lot of faith in the scientific community in recent years having seen it act in ways very similar to the ivory tower religions it was supposed to replace. Ridicule, adherence to dogma, character assassination and innuendo are all tools explored with relish by the science establishment and woe betide anyone attempting to subvert currently accepted theory.

The Simple Electric Universe