Searches for diffuse X - ray emission around millisecond pulsars : An X - ray nebula associated with PSR J 2124 − 3358

We report on diffuse X-ray emission associated with the nearby solitary millisecond pulsar PSR J2124−3358 detected with XMM-Newton and Chandra. The emission extends from the pulsar to the northwest by ∼ 0.5 arcmin. The spectrum of the nebular emission can be modeled with a power-law of photon index 2.2 ± 0.4, in line with the emission originating from accelerated particles in the post shock flow. For PSR J0437−4715, PSR J0030+0451 and PSR J1024−0719, which all have spin parameters comparable to that of PSR J2124−3358, no diffuse emission is detected down to a 3 − σ limiting flux of ∼ 4 − 7 × 10 −15 ergs s −1 cm −2 .