Discovery of extended X-ray emission around the highly magnetic RRAT J1819-1458

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We report on the discovery of extended X-ray emission around the high magnetic field Rotating Radio Transient J1819-1458. Using a 30ks Chandra ACIS-S observation, we found significant evidence for extended X-ray emission with a peculiar shape: a compact region out to 5.5", and more diffuse emission extending out to 13" from the source. The most plausible interpretation is a nebula somehow powered by the pulsar, although the small number of counts prevents a conclusive answer on the nature of this emission. RRAT J1819-1458's spin-down energy loss rate (Edot 3x10³² erg/s) is much lower than that of other pulsars with observed spin-down powered pulsar wind nebulae (PWNe), and implies a rather high X-ray efficiency of etaₓ = L(pwn; 0.5-8keV)/Edot 0.2 at converting spin-down power into the PWN X-ray emission. This suggests the need of an additional source of energy rather than the spin-down power alone, such as the high magnetic energy of this source. Furthermore, this Chandra observation allowed us to refine the positional accuracy of RRAT J1819-1458 to a radius of 0.3", and confirms the presence of X-ray pulsations and the 1keV absorption line, previously observed in the X-ray emission of this source.