A message from Crab Pulsar in TeraelectronVolt fonts
The Crab Pulsar, PSR J0534+220, is a young neutron star that was created after the supernova explosion SN1054.
Its mass is about 1.5 times the mass of the Sun, concentrated in an object of about 10 km diameter. It rotates 33 times per second, and it is surrounded by a
region of intense magnetic field ten thousand billion times stronger than that of the Sun.
This field is strong enough to dominate the motion of charges and forces charged particles to rotate and spiral around the neutron star.
This region is called the magnetosphere.
The rotation of the magnetic field generates intense electric fields that literally tear charged particles from the surface.
As accelerated charged particles stream outward, they produce beams of radiation that we receive every time the beam crosses our line of sight, like it happens with a lighthouse.
The Crab is the most powerful pulsar in our Galaxy. It is one of the few pulsars that has been detected
across the electromagnetic spectrum from radio up to gamma rays, and is one of the brightest at high energies.
Its pulsar wind nebula, the Crab nebula, is also the standard candle for
many experiments detecting gamma-rays, as MAGIC: in 2008 for the first time pulsed emission was discovered
in the Very High Energy range (E. Aliu et al., Science, 322, 1221(2008)), revolutionizing the existing models of pulsars as the Polar Cap model.
Following that discovery, in 2011 and 2012 the energy range of the emission observed from Crab Pulsar expanded up to 400 Giga Electron Volts (GeV), and also bridge emission between
the pulsed peaks was detected: now after an extensive work collecting ~320 hours of very good quality data observing Crab, MAGIC reported in the paper published
in A&A vol. 585, A133 (2016)
the discovery of the highest pulsed emission ever detected in our Universe, 1.5 Tera Electron Volts(TeV).
The mechanism behind such an unexpected highly energetic gamma-ray emission is not easy to be understood. The existing models fail to describe the extension of
the emitted energy up to 1.5 TeV, that could only be ascribed to an Inverse Compton process at work in the Crab pulsar, dominating the emission of gamma-rays
above 50 GeV.
The new results probe the Crab Pulsar as the most compact TeV accelerator known to date, and require a revision of the state-of-the-art models proposed to explain
how and where gamma-ray pulsed emission up to 1.5 TeV are produced.
Due to the big amount of data used for this research it was also possible to perform a detailed study of how the pulsar emission (phaseogram) changes with energy.
These results are key for the understanding of pulsars and will be an hard test for new theories to come.
Image Credits: Patricia Carcelén Marco
Figure: The neutron star (red sphere) with its strong magnetic field (white lines) spins
around itself nearly 30 times per second injecting energetic electrons in the space region
around it. The green and blue shaded regions depict different particle acceleration zones
from where the detected photons could originate. The green zone lies in the vicinity of the
pulsar's magnetosphere, whereas the blue zone could be as far as 100.000 km away from the pulsar