Suzaku observations of the hard X-ray spectrum of Vela Jr

We report the results of Suzaku observations of the young supernova remnant, VelaJr.\ (RX J0852.0$-$4622), which is known to emit synchrotron X-rays, as well as TeV gamma- rays. Utilizing 39 Suzaku mapping observation data from VelaJr., a significant hard X-rayemission is detected with the hard X-raydetector (HXD) from the north-west TeV-emitting region. The X-rayspectrum is well reproduced by a single power-lawmodel with the photon index of 3.15$^{+1.18}_{-1.14}$ in the 12--22 keV band. Compiling this with the soft X-rayspectrum simultaneously observed with the X-ray imaging spectrometer(XIS) onboard Suzaku, we find that the wide-band X-rayspectrum in the 2--22 keV band is reproduced with a single power-lawor concave broken power-lawmodel, which are statistically consistent with each other. Whichever the model of a single or broken power-lawis appropriate, clearly the spectrum has no rolloff structure. Applying this result to the method introduced in \citet{yama2014}, we find that one-zone synchrotron model with electron spectrum having a power-lawplus exponential cutoff may not be applicable to VelaJr.