Speaker
Description
Although the Crab Nebula is one of the best-studied astrophysical sources, its extension in gamma-rays remained unknown until now. Measuring the size of the Crab Nebula in very high energy (VHE) gamma-rays provides important input on understanding the physics of this quite unusual pulsar wind nebula. The suspected extension is well below the angular resolution of Imaging Atmospheric Cherenkov Telescopes, which makes a good understanding of the instrument point spread function (PSF) indispensable. The PSF depends strongly on the observation and instrument conditions, demanding time-dependent simulations of these. Utilising such simulations, the point-source resolvability in VHE gamma-ray astronomy has now been pushed to a new level by H.E.S.S., allowing to probe source extensions well below one arcminute scale. This enables us to reveal the extension of the Crab Nebula in VHE gamma-rays for the first time. Assuming a Gaussian source shape, we obtain a width of 52’’.
