A Near-Infrared image of the Crab Nebula, showing the toroidal wind and a jet.
The Fermi-LAT telescope, a γ-ray telescope operated by NASA, detected large flares from the Crab Nebula going back as far as 20071. The flares cause the Crab Nebula to brighten by a factor of 30 in the γ-ray, with a consistent spectral shape, 8 hour rise time, and multiple peak structure.
The high flux increase in the γ-ray makes the Crab Nebula one of the most variable objects in the night sky. The short rise time suggests that these flares originate from a small physical area (using causality arguments, we can suggest that the flares originate from an area smaller than 0.3").
I use the adaptive optics systems at Keck Observatory to search for structures that are small enough to be the origin of the large γ-ray flares. In order to understand the “normal” variations that occur in this dynamic nebula, we have to monitor the conditions in the nebula on a regular basis. The video below shows these “normal” variations.
Within these normal variations, I search for unusual movements and changes which might indicate a source for the γ-ray flares. Our search suggests that the γ-ray flares may be due to interacting magnetic fields at a violent shock front.