MessageToEagle.com - There are complex processes taking place in the Milky Way, which are difficult for astrophysicists to explain.
Apparently, the famous Crab Nebula is a veritable bundle of energy.
Two MAGIC (Major Atmospheric Gamma-Ray Imaging Cherenkov) Telescopes on the Canary island of La Palma,
confirm that the pulsar at the centre of this famous object is a great bundle of energy.
The instruments measure the highest-energy gamma rays from a pulsar to date, calling theory into question.
The pulsar in the area are of 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 energy of up to 400 GeV – 50 to 100 times higher than theorists thought possible.
"There must be processes behind this that are as yet unknown", says Razmik Mirzoyan, project head at the Max Planck
Institute of 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.
These particles move along magnetic field lines that rotate at the same speed as the neutron star itself, giving off beams
almost everywhere in 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.
Click on image to enlarge
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 pulsar's 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 (Graphics: NASA, ESA, J. Hester, A. Loll, CXC, SAO, F. Seward et al., MAGIC Collaboration).
A few years ago, the MAGIC telescopes detected gamma rays of energy ≥ 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 have been produced at least 60 kilometres
above the surface of the neutron star.
This is because the high-energy gamma rays 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.
High-energy gamma-ray variability of the Crab Nebula
This image of the Crab Nebula is a composite of images taken in the infrared (purple, Spitzer observatory), visible light
(yellow, Hubble Space Telescope) and X-rays (blue, Chandra observatory). The observed light is emitted by electrons accelerated
at high (blue) and lower (purple) energies. Several short and intense flares of gamma-rays, detected by the Fermi satellite
(inset) are the signature of electrons accelerated close to the center of the nebula. These are the electrons with the
highest energy ever detected in the Universe.
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? Neutron stars 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.
Now the data measured by MAGIC over the course of 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.
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 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.
Exotic Millions Of Years Old Dying Pulsar Still Kicking!
At an age of about 200 million years, this pulsar is the oldest and faintest isolated pulsar ever detected in X-rays but it's
spinning only slightly faster than one revolution per second!
Among isolated pulsars, it is over 10 times older than the previous record holder with an X-ray detection.
Oldest Alien Worlds Discovered - Born At Dawn Of Universe
A group of European astronomers has discovered an ancient planetary system that is likely to be a survivor from one of the earliest cosmic eras, 13 billion years ago.
The system consists of the star HIP 11952 and two planets, which have orbital periods of 290 and 7 days, respectively.
Spectacular Infrared Images Of Galaxies Released
For the first time, the general public will be able to browse detailed infrared images of more than 200 galaxies.
The pictures, originating from data from the orbiting Spitzer Space Telescope, are currently being released to the general public.
Amongst the images are the objects M60, M61, M88, M91 and M98, all of which lie between 47 and 63 million light years away in
the large cluster of galaxies found in the direction of the constellation of Virgo.
Hidden Misshapen Celestial "Wonder"
It is one of the brightest and strangest objects in the Milky Way - the corpse of a star that exploded around 1000 years ago.
Only a handful of such young supernova remnants are known.
The object named G350.1-0.3 is also incredibly small (only eight light years across) and young in astronomical terms.
Alien Species Living In The Inner Milky Way Could Be In Danger
Few people doubt there is intelligent alien life in the Milky Way galaxy, but where can we expect to find it?
Astronomers think that while the inner sector of the MIlky Way Galaxy may be the most likely to support habitable worlds.
Unfortunately some of these places are also most dangerous to all life-forms.
Black Holes With No 'Table Manners' Eat Two Courses At Once!
It is still unknown how the supermassive black holes (SMBH) in galaxy centres accrete gas and grow.
Researchers from the University of Leicester (UK) and Monash University in Australia have investigated how some black holes got so big so fast that they are billions of times heavier than the sun.
Mercury Surprises Scientists
On March 17, MESSENGER (MErcury Surface, Space Environment, GEochemistry, and Ranging) completed its one-year primary mission, orbiting Mercury, capturing nearly 100,000 images, and recording data
that reveals new information about the planet's core, topography, and the mysterious radar bright material in the permanently shadowed areas near the poles.
Living Earth Simulator - Supercomputer Predicting The Future
In Douglas Adams book the Hitchhikers Guide to the Galaxy we encounter a machine called Deep Thought. It is the most powerful computer ever built. Deep Thought is capable of answering questions
concerning life, the Universe, and simply everything. Now scientists are planning to create a similar machine. It is called the Living Earth Simulator (LES).
Warp-Speed Planets Are Some Of The Fastest Objects In The Milky Way
Warped planets are some of the fastest objects in the Milky Way and they zoom through space near the speed of light.
Some years ago astronomers were astonished when they they found the first runaway star flying out of our Galaxy at a speed of 1.5 million miles per hour.
The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?
Though the universe is filled with billions upon billions of stars, the discovery of a single variable star in 1923 altered the
course of modern astronomy. And, at least one famous astronomer of the time lamented that the discovery had shattered his world view.
Astronomical Mystery - Tremendous Explosion And Appearance Of Odd Rings
Twenty five years ago, on 1987 February 23, the brightest supernova of modern times was observed in the Large Magellanic Cloud.
The collision occurred at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow.
Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material...
The "Cloaked" Star Was Difficult To Find
An object obscured by dust, and buried in a two-star system enshrouded by dense gas, is not easy to find.
A "cloaked" star was discovered after it ate a little of its neighbor. The meal must have given the star a bit of indigestion, because it
"burped" with a blast of high-energy radiation, which gave it away.