The \sim 10 ^ { 4 } y old ( catalog Vela Pulsar ) represents the bridge between the young Crab-like and the middle-aged rotation powered pulsars .
Its multiwavelength behaviour is due to the superposition of different spectral components .
We take advantage of the unprecedented harvest of photons collected by XMM-Newton to assess the ( catalog Vela Pulsar ) spectral shape and to study the pulsar spectrum as a function of its rotational phase .
In order to fully exploit the data collected by XMM-Newton on the Vela pulsar , we had first to discriminate the pulsar emission from that of the bright surrounding nebula .
To this aim , we used the Chandra /HRC surface brightness map of the nebula , coupled with the most accurate calibration of the EPIC point spread function .
This procedure made it possible to assess the pulsar spectral shape , disentangling its thermal component from the non thermal one .
As for the middle-aged pulsars Geminga , PSR B0656+14 and PSR B1055-52 ( the “ Three Musketeers ” ) , the phase-integrated spectrum of Vela is well described by a three-component model , consisting of two blackbodies ( T _ { \mathrm { bb } } = 1.06 \pm 0.03 \times 10 ^ { 6 } \mathrm { K } , R _ { \mathrm { bb } } = 5.1 ^ { +0.4 } _ { -0.3 } \mathrm { km } , T _ { \mathrm { BB } } = 2.16 ^ { +0.06 } _ { -0.07 } \times 10 ^ { 6 } \mathrm { K } , R _ { \mathrm { BB } } = 0.73 ^ { +0.09 } _ { -0.07 } \mathrm { km } ) plus a power-law ( \gamma = 2.2 ^ { +0.4 } _ { -0.3 } ) .
The relative contributions of the three components are seen to vary as a function of the pulsar rotational phase .
The two blackbodies have a shallow \sim 7 - 9 \% modulation .
The cooler blackbody , possibly related to the bulk of the neutron star surface , has a complex modulation , with two peaks per period , separated by \sim 0.35 in phase , the radio pulse occurring exactly in between .
The hotter blackbody , possibly originating from a hot polar region , has a nearly sinusoidal modulation , with a single , broad maximum aligned with the second peak of the cooler blackbody , trailing the radio pulse by \sim 0.15 in phase .
The non thermal component , magnetospheric in origin , is present only during 20 % of the pulsar phase and appears to be opposite to the radio pulse .
XMM-Newton phase-resolved spectroscopy unveils the link between the thermally emitting surface of the neutron star and its charge-filled magnetosphere , probing emission geometry as a function of the pulsar rotation .
This is a fundamental piece of information for future 3-dimensional modeling of the pulsar magnetosphere .