Powerhouse in the Crab Nebula

Mar 29, 2012
Cosmic lighthouse: The Crab Pulsar emits gamma ray pulses measuring up to 400 gigaelectronvolts (GeV); that is, at least 50 times higher than theorists thought possible. The animation shows the pulsed emissions as measured by the two MAGIC telescopes. Credit: S. Klepser, MAGIC Collaboration

MAGIC telescopes measure the highest-energy gamma rays from a pulsar to date, calling theory into question.

The pulsar at the centre of the famous is a veritable bundle of energy. This was now confirmed by the two MAGIC  Telescopes on the Canary island of La Palma. They observed the pulsar in the very high energy gamma radiation from 25 up to 400 gigaelectronvolts (GeV), a region that was previously difficult to access with high energy instruments, and discovered that it actually emits pulses with the maximum measurable energy of up to 400 GeV – at least 50 to 100 times higher than theorists thought possible. These latest observations are difficult for astrophysicists to explain. "There must be processes behind this that are as yet unknown", says Razmik Mirzoyan, project head at the Max Planck Institute for Physics.

The neutron star in the Crab Nebula is one of the best known pulsars. It rotates around its own axis 30 times every second and has a magnetic field of 100 million Tesla, over a trillion times stronger than that of Earth. The pulsar powers the surrounding  famous Crab Nebula, located about 6000 light-years from Earth in the constellation of Taurus. Both the pulsar and the nebula are remnants of a supernova which exploded in July 1054 AD and was visible to the naked eye even by daylight for 23 days.

Neutron stars are extremely dense spheres made of nuclear material. Their mass is similar to that of the sun, but they have diameters of just 20 kilometres. But what makes a neutron star a pulsar, of which astrophysicists have detected some 2000 in our Milky Way galaxy? have an extremely regular and very short rotation period or "day", ranging from one millisecond to ten seconds. While rotating, the star constantly emits charged particles, mainly electrons and positrons (positively charged electrons) and electromagnetic radiation.

In a different light: The illustration shows the Crab Nebula as seen through an optical telescope (left) and an X-ray telescope (middle), with a graphic representation of the pulsars magnetic field (right). The light curve (bottom) shows the regular emission of gamma rays at intervals of 0.0337 seconds, or two pulses per rotation. For clarity two periods are shown. Credit: NASA, ESA, J. Hester, A. Loll, CXC, SAO, F. Seward et al., MAGIC Collaboration

These particles move along magnetic field lines that rotate at the same speed as the neutron star itself, giving off beams almost everywhere the electromagnetic spectrum, from radio wavelengths to gamma rays. If one of these beams crosses our line of sight, the star flashes up for a moment, just like the signal from a lighthouse.

A few years ago, the MAGIC telescopes detected gamma rays of energy higher than 25 GeV from the Crab Pulsar. This was very unexpected since the available EGRET satellite data were showing that the spectrum ceases at much lower energies. However, at the very high energies MAGIC demonstrated to have few orders of magnitudes higher sensitivity compared to the satellite missions. At the time, scientists concluded that the radiation must be produced at least 60 kilometres above the surface of the neutron star. This is because the high-energy are so effectively shielded by the star's magnetic field that a source very close to the star could not be detected. As a consequence that measurement ruled out one of the main theories on high energy gamma-ray emission from the Crab pulsar.

Now the data measured by MAGIC over the past two years show that the pulsed emissions by far exceed all expectations, reaching 400 GeV in extremely short pulses of about a millisecond duration. This finding casts doubt on existing theories, since it was thought that all pulsars had significantly lower energy limits.The recent measurements by MAGIC, together with those of the orbiting Fermi satellite at much lower energies, provide an uninterrupted spectrum of the pulses from 0.1 GeV to 400 GeV. These clear observational results create major difficulties for most of the existing pulsar theories that predict significantly lower limits for highest energy emission.

A new theoretical model developed by MAGIC team associate Kouichi Hirotani of the Academia Sinica, Institute of Astronomy and Astrophysics in Taiwan explains the phenomenon with a cascade-like process which produces secondary particles that are able to overcome the barrier of the pulsar's magnetosphere. Another possible explanation posed by Felix Aharonian of the Dublin Institute for Advanced Studies and other researchers links the puzzling emission to the similarly enigmatic physics of the pulsar wind  – a current of electrons, positrons and electromagnetic radiation which ultimately develops into the Crab Nebula.

However, even though the  above models are able to provide  explanations for the extremely high energy and  the shortness of the pulses, further refinements are necessary for achieving a good agreement with observations. Astrophysicists hope that future observations will improve the statistical precision of the data and help solving  the mystery. This could  shed new light on pulsars and on the Crab Nebula itself, as one of the most studied objects in our Milky Way.

Explore further: Image: Galactic wheel of life shines in infrared

More information: MAGIC Collaboration, J. Aleksic et al., Phase-resolved energy spectra of the Crab pulsar in the range of 50-400GeV measured with the MAGIC telescopes, Astronomy & Astrophysics, March 30, 2012

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Callippo
5 / 5 (1) Mar 29, 2012
The animations in form of jpeg image require a bit too much patience to watch... There is one from the original source
thingumbobesquire
1 / 5 (6) Mar 29, 2012
Since Astrophysicists admit that "There must be processes behind this that are as yet unknown," how can any of their grand big bang models of unification theories be taken for anything other than mere mathematical figments?
Tuxford
1 / 5 (6) Mar 29, 2012
how can any of their grand big bang models of unification theories be taken for anything other than mere mathematical figments?


Math models gone wild....

This is old news. LaViolette has pointed out these energy problems with the crab for many years, since 1983. If astronomers want to learn what is happening, they should check his blog. The crab is direct evidence for a passing superwave of cosmic ray electrons, currently illuminating the nebula.

http://starburstf...g/?p=238
Tuxford
1 / 5 (2) Mar 29, 2012
While the illumination of the nebula is unrelated to the pulsar itself, these extremely energetic periodic pulses from the pulsar itself are consistent with LaViolette's analysis postulating an artificial source. He notes that an artifically-generated compact region of magnetic fields projected near the pulsar surface could modulate the relativistic electrons emanating from the neutron star, to produce the observed gamma ray pulse train. He notes that typically these pulse trains include repeating phase train modes, that shift, delay and repeat. There are many repeating mode variations from various pulsars that are virtually impossible to explain as a naturally sourced.

http://starburstf...ti2blog/

http://starburstf...g/?p=182

No wonder astronomers have so much trouble with these strange objects. Laviolette too had problems fitting them into his cosmological model. He finally concluded that they don't fit for a very significant reason!
0FET
not rated yet Mar 29, 2012
"This is because the high-energy gamma rays are so effectively shielded by the star's magnetic field" -- how is this possible? I could imagine that the high concentration of charged particles close to the neutron star's surface absorbs gamma rays, but how can the magnetic field itself shield them?
Callippo
2 / 5 (2) Mar 29, 2012
high-energy gamma rays are so effectively shielded by the star's magnetic field" -- how is this possible?
The strong magnetic or even gravitational field increases the probability of materialization of photons with CMBR field, because the resulting particle-antiparticle pairs are separated each other with magnetic field (and the gravity field acts in similar way, when the pairs are moving perpendicularly to its gradient). The similarity of this mechanism with mechanism of Hawking radiation is not accidental here - it's just dual version of it. In real life we can met with this effect at the case of so-called Magnus-Robins force.
Callippo
1 / 5 (1) Mar 29, 2012
Another analogy is the solar cell where the photons hit the potential gradient of semiconductor junction: the electron and holes are getting separated each other here, so that junction generates fotocurrent. At the case of neutron star the fotocurrent is represented with jets of particles at poles, where the gradient of field is most prominent.
0FET
not rated yet Mar 29, 2012
thanks for the explanation, Callippo!
Vendicar_Decarian
1 / 5 (1) Mar 29, 2012
http://www.youtub...riGSOaLg

"While the illumination of the nebula is unrelated to the pulsar itself..." - TuxTard
Lurker2358
1 / 5 (1) Mar 29, 2012
I figure this sucker is probably borderline black hole status, only just missed it, and I still think it probably represents a previously un-described type of supernova.

I still say matter-anti-matter anihilation is the only mechanism capable of generating the amount of energy needed to destroy the star in the way it happened, given the mass of the expanding nebula and the relatively puny mass of the neutron star itself. There isn't enough mass available to explain it through ordinary fusion, pair instabilities, or gravitational stuff.

The ultra-high energy gamma could be coming from the relativistic mass of anti-matter particles colliding with ordinary matter near the speed of light.

Like for example, if you have enough particle collisions then you might create an anti-proton, and then it could collide with a proton and annihilate, and since they are also both moving at relativistic velocities, the "mass" converted to gamma is much more.
jsdarkdestruction
5 / 5 (1) Mar 30, 2012
tuxford, why not mention that reason? its because he thinks the pulsars were put there as part of a secret code by an advanced race to warn us of galactic superwaves and how matter is actually formed and how the universe works. yep, pulsars are actually beacons sending us messages/codes from intelligent life far more advanced than we are.....
Oh yeah, cuz it shows laviolette is a crank.
Tuxford
1 / 5 (2) Mar 30, 2012
Back in your dark intellectual closet Dark. You are safe from new ideas there.
jsdarkdestruction
5 / 5 (1) Mar 30, 2012
txford, you are the one who likes to leave out important details. why keep everyone in the dark and only tell part of the story? as lavioletes ideas certainly cant be considered real science. Ancient aliens? codes in the stars? You call that drivel science? Get real...
HannesAlfven
1 / 5 (2) Apr 01, 2012
Re: These latest observations are difficult for astrophysicists to explain. "There must be processes behind this that are as yet unknown"

The gravity-based scientific framework consistently runs into problems when trying to explain the energies we see associated with objects. It is the framework that is the problem. Gravity is just not strong enough to explain these phenomena. We need E&M, but the problem is that the plasma models model cosmic plasmas as though they have no, or little, E&M. That simplifies the calculations, and fits it to the assumptions of a gravity-based universe. The only way forward which can accommodate all of our observations is to stop assuming that cosmic plasmas cannot sustain E-fields; to stop modeling the cosmic plasmas as though they are superconductors with zero resistance; and to stop assuming that the magnetic fields are frozen into the cosmic plasmas.

Until that point, the astrophysicists will continue to waste OUR money and time.
HannesAlfven
1 / 5 (2) Apr 01, 2012
Re: "A new theoretical model developed by MAGIC team associate Kouichi Hirotani of the Academia Sinica, Institute of Astronomy and Astrophysics in Taiwan explains the phenomenon with a cascade-like process which produces secondary particles that are able to overcome the barrier of the pulsar's magnetosphere. Another possible explanation posed by Felix Aharonian of the Dublin Institute for Advanced Studies and other researchers links the puzzling emission to the similarly enigmatic physics of the pulsar wind a current of electrons, positrons and electromagnetic radiation which ultimately develops into the Crab Nebula."

Epicycles.

Ditch the neutron star and the gravity-based framework, and just switch to a current-based theory for pulsars.

Problem solved.

As David Bohm once stated, it is our own minds which cause most of the problems which we must then solve.
Graeme
not rated yet Apr 03, 2012
0FET> high energy gamma rays interact with magnetic fields to produce positron electron pairs, being the reverse of positron meeting electron producing gamma rays. Magnetic fields parallel to the photon path will not affect it, so there will be a window for gamma rays out from the magentic poles of the pulsar. We would only see through this window if the magnetic pole is aligned with earth. Gama rays with less than 100 Petaelectron volts (100Pev) can penetrate earth's magnetic field.

For those that like to compare things with real life, the energy here is like that in a flying mosquito wing.