Detection of the hard X-ray non-thermal emission from Kepler's supernova remnant

Abstract

We report the first robust detection of the hard X-ray emission in the 15--30\,keV band from Kepler's supernova remnant with the silicon PIN-type semiconductor detector of the hard X-ray detector (HXD-PIN) onboard Suzaku. The detection significance is 7.17 $\sigma$ for the emission from Kepler's entire X-ray emitting region. The energy spectrum is found to be well reproduced by a single power-law function with a photon index of $3.13_{-1.52-0.36}^{+1.85+0.69}$, where the first and second errors represent 90\%-statistical and systematic errors, respectively. The X-ray flux is determined to be 2.75${}_{-0.77-0.82}^{+0.78+0.81}\times 10^{-12}$\,erg\,s${}^{-1}$\,cm${}^{-2}$ in the 15--30\,keV band. The wider-band X-ray spectrum in the 3--30\,keV band, where the soft X-ray Suzaku/XIS spectrum is combined, shows that the non-thermal component does not have a significant X-ray roll-off structure. We find that the broad-band energy spectrum from the radio band, X-ray data of this work, and TeV upper limits can be reproduced with the one-zone leptonic model with a roll-off energy of ${\nu }_{\mathrm{roll}}=1.0\times 10^{17}$\,Hz and magnetic field strength of $B>40\mu \mathrm{G}$. Application of the diagnostic method using indices in the soft and hard X-ray band to the data indicates that the maximum energy of the accelerated electrons in Kepler's SNR is limited by the age of the remnant. The indication is consistent with the results of the one-zone leptonic modeling.

11 pages, 7 figures, 4 tables, accepted for publication in PASJ

References in corpus (13)

• On the use of C-stat in testing models for X-ray spectra
• INTEGRAL/IBIS all-sky survey in hard X-rays
• Study of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku
• Confirmation of strong magnetic field amplification and nuclear cosmic ray acceleration in SN 1006
• A Deep Chandra Observation of Kepler's Supernova Remnant: A Type Ia Event with Circumstellar Interaction
• Fast Variability of Nonthermal X-Ray Emission in Cassiopeia A: Probing Electron Acceleration in Reverse-Shocked Ejecta
• Magnetic-Field Amplification in the Thin X-ray Rims of SN1006
• Forward Shock Proper Motions of Kepler's Supernova Remnant
• A possible approach to three-dimensional cosmic-ray propagation in the Galaxy IV. Electrons and electron-induced gamma-rays
• Expansion and Age of the X-ray Synchrotron-Dominated Supernova Remnant G330.2+1.0
• Freely Expanding Knots of X-ray Emitting Ejecta in Kepler's Supernova Remnant
• Time Variability of Nonthermal X-ray Stripes in Tycho's Supernova Remnant with Chandra
• Temporal and Spatial Variation of Synchrotron X-ray Stripes in Tycho's Supernova Remnant

Cited by in corpus (6)

• Spatially Resolved RGS Analysis of Kepler's Supernova Remnant
• A spatially resolved study of hard X-ray emission in Kepler's SNR: indications of different regimes of particle acceleration
• Evidence for gamma-ray emission from the remnant of Kepler's supernova based on deep H.E.S.S. observations
• A Third Epoch Proper Motion Study of The Forward Shock in Kepler's Supernova Remnant
• Estimating Ejecta Mass Ratios in Kepler's SNR: Global X-Ray Spectral Analysis Including Suzaku Systematics and Emitting Volume Uncertainties
• NuSTAR discovery of the hard X-ray emission and a wide-band X-ray spectrum from the Pictor A western hot spot