X-ray synchrotron emission from 10-100 TeV cosmic-ray electrons in the supernova remnant SN 1006

We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission o ver the entire X-ray energy band from 0.12 to 17 keV. The thermal flux is d escribed by a nonequilibrium ionization model with an electron temperature kT(e) = 0.6 keV, an ionization timescale n(0)t = 9x10(9) cm(-3) s, and a re lative elemental abundance of silicon that is 10-18 times larger than the s olar abundance. The nonthermal X-ray spectrum is described by a broken powe r law model with low- and high-energy photon indices Gamma (1) = 2.1 and Ga mma (2) = 3.0, respectively. Since the non- thermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate pr evious claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larg er than previous estimates of about 10 muG and arbitrarily use a value of 4 0 muG to estimate the parameters of the cosmic-ray electron, proton, and he lium spectra of the remnant. The results for the ratio of the number densit ies of protons and electrons (R=160 at 1 GeV), the total energy in cosmic r ays (E-cr = 1x10(50) ergs), and the spectral index of the electrons at 1 Ge V (Gamma (e) = 2.14 +/-0.12) are consistent with the hypothesis that Galact ic cosmic rays are accelerated predominantly in the shocks of supernova rem nants. Yet, the remnant may or may not accelerate nuclei to energies as hig h as the energy of the "knee" depending on the reason why the maximum energ y of the electrons is only 10 TeV.