Context :

Aims : PSR J1846 - 0258 is a young rotation-powered pulsar with one of the highest surface magnetic field strengths , located in the centre of SN-remnant Kes-75 .
In June 2006 a magnetar-like outburst took place .
Using multi-year RXTE and INTEGRAL observations covering also the epoch of the outburst we aim to study the temporal and spectral characterisitics of PSR J1846 - 0258 over a broad \sim 3-300 keV energy range to derive constraints on theoretical scenarios aiming to explain this schizophrenic behaviour .

Methods : We explored all publically available RXTE observations of PSR J1846 - 0258 to generate accurate ephemerides over the period January 30 , 2000 - November 7 , 2007 .
Phase folding procedures yielded pulse profiles for RXTE PCA ( \sim 3 - 30 keV ) , RXTE HEXTE ( \sim 15 - 250 keV ) and INTEGRAL ISGRI ( \sim 20 - 300 keV ) .
The pulsed spectrum over the full \sim 3 - 300 keV energy range was derived , as well as the total spectrum ( including the Pulsar Wind Nebula ) over the 20-300 keV band with the ISGRI .
The timing , spatial and spectral analyses have been applied for epochs before , during and after the magnetar-like outburst to study the evolution of the high-energy characteristics .

Results : ISGRI detected PSR J1846 - 0258/Kes-75 before outburst during 2003-2006 with a power-law-shape spectrum over the 20-300 keV energy range with photon index \Gamma = 1.80 \pm 0.06 and energy flux ( 20-300 keV ) of ( 6.62 \pm 0.35 ) \times 10 ^ { -11 } erg/cm ^ { 2 } s. More than 90 days after the onset of the outburst , still during the decay phase , the same spectral shape was measured ( \Gamma = 1.75 _ { -0.31 } ^ { +0.27 } ) with an indication for a 52 % ( 2.3 \sigma ) enhanced total emission , while one year after the outburst the hard X-ray non-thermal emission of PSR J1846 - 0258/Kes-75 was found to be back to its pre-outburst values .
PCA monitoring of PSR J1846 - 0258 before the outburst yielded phase-coherent ephemerides confirming the earlier derived breaking index of the spindown .
During the outburst incoherent solutions have been derived .
We showed that the radiative outburst was triggered by a major spin-up glitch near MJD 53883 \pm 3 with a glitch size \Delta \nu / \nu in the range ( 2.0 - 4.4 ) \times 10 ^ { -6 } .
Using all pre-outburst observations of ISGRI and HEXTE for the first time pulse profiles have been obtained up to 150 keV with a broad single asymmetric pulse .
The pulse shape did not vary with energy over the 2.9-150 keV energy range , nor did it change during the magnetar-like outburst .
The time-averaged pre-outburst \sim 3-300 keV pulsed spectrum measured with the PCA , HEXTE and ISGRI was fitted with a power-law model with \Gamma = 1.20 \pm 0.01 .
A fit with a curved power-law model gives an improved fit .
Around 150 keV the pulsed fraction approaches 100 % .
The first 32 days of the magnetar-like outburst the 3-30 keV pulsed spectrum can be represented with two power laws , a soft component with index \Gamma _ { s } = 2.96 \pm 0.06 and a hard component with the pre-outburst value \Gamma _ { h } \sim 1.2 .
Above \sim 9 keV all spectra during outburst are consistent with the latter single power-law shape with index \sim 1.2 .
The 2-10 keV flux increased by a factor \sim 5 and the 10-30 keV flux increased with only 35 % .
After \sim 120 days the soft outburst and the enhancement of the hard non-thermal component both vanish .

Conclusions : The varying temporal and spectral characteristics of PSR J1846 - 0258 can be explained in a scenario of a young high-B-field pulsar in which a major glitch triggered a sudden release of energy .
Resonant cyclotron upscattering could subsequently generate the decaying / cooling soft pulsed component measured during outburst between 3 and 10 keV .
The ( variation in the ) non-thermal hard X-ray component can be explained with synchrotron emission in a slot-gap or outer-gap pulsar model .