中国科学院云南天文台机构知识库

A deep hard X-ray survey of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has detected for the first time non-thermal emission up to 90 keV in the Tycho supernova (SN) remnant. Its 3-100 keV spectrum is fitted with a thermal bremsstrahlung of kT similar to 0.81 +/- 0.45 keV plus a power-law model of Gamma similar to 3.01 +/- 0.16. Based on diffusive shock acceleration theory, this non-thermal emission, together with radio measurements, implies that the Tycho remnant may not accelerate protons up to >PeV but to hundreds TeV. Only heavier nuclei may be accelerated to the cosmic ray spectral "knee." In addition, using INTEGRAL, we search for soft gamma-ray lines at 67.9 and 78.4 keV that come from the decay of radioactive Ti-44 in the Tycho remnant. A bump feature in the 60-90 keV energy band, potentially associated with the Ti-44 line emission, is found with a marginal significance level of similar to 2.6 sigma. The corresponding 3 sigma upper limit on the Ti-44 line flux amounts to 1.5 x 10(-5) photon cm(-2) s(-1). Implications on the progenitor of the Tycho SN, considered to be a Type Ia SN prototype, are discussed.