PSR J1819–1458 is a rotating radio transient ( RRAT ) source with an inferred surface dipole magnetic field strength of 5 \times 10 ^ { 13 } G and a 4.26-s spin period .
We present XMM-Newton observations of the X-ray counterpart of this source , CXOU J181939.1–145804 , in which we identify pulsations and a possible spectral feature .
The X-ray pulsations are at the period predicted by the radio ephemeris , providing an unambiguous identification with the radio source and confirmation of its neutron star nature .
The X-ray pulse has a 0.3–5 keV pulsed fraction of 34 % and is aligned with the expected phase of the radio pulse .
The X-ray spectrum is fit well by an absorbed blackbody with kT = 0.14 keV with the addition of an absorption feature at 1 keV , with total absorbed flux of 1.5 \times 10 ^ { -13 } ergs cm ^ { -2 } s ^ { -1 } ( 0.3–5 keV ) .
This absorption feature is well modeled by a Gaussian or resonant cyclotron scattering model , but its significance is dependent on the choice of continuum model .
We find no evidence for any X-ray bursts or aperiodic variability on timescales of 6 ms to the duration of the observation and can place the most stringent limit to date of \leq 3 \times 10 ^ { -9 } ergs cm ^ { -2 } s ^ { -1 } on the absorbed 0.3–5 keV flux of any bursts .