Chandra X‐Ray Observations of G11.2−0.3: Implications for Pulsar Ages

Abstract

We present Chandra X-Ray Observatory imaging observations of the young Galactic supernova remnant G11.2-0.3. The image shows that the previously known young 65 ms X-ray pulsar is at position (J2000) RA. 18h11m29s.22, decl. -19°25′27″.6, with 1 σ error radius of 0″.6. This is within 8″ of the geometric center of the shell. This provides strong confirming evidence that the system is younger, by a factor of ∼12, than the characteristic age of the pulsar. The age discrepancy suggests that pulsar characteristic ages can be poor age estimators for young pulsars. Assuming conventional spin-down with constant magnetic field and braking index, the most likely explanation for the age discrepancy in G11.2-0.3 is that the pulsar was born with a spin period of ∼62 ms. The Chandra image also reveals, for the first time, the morphology of the pulsar wind nebula. The elongated hard X-ray structure can be interpreted as either a jet or a Crab-like torus seen edge-on. This adds to the growing list of highly aspherical pulsar wind nebulae and argues that such structures are common around young pulsars.