Hard X-Ray Emission and 44Ti Line Features of the Tycho Supernova Remnant
Abstract
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 ~ 0.81 ± 0.45 keV plus a power-law model of Γ ~ 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 44Ti in the Tycho remnant. A bump feature in the 60-90 keV energy band, potentially associated with the 44Ti line emission, is found with a marginal significance level of ~2.6σ. The corresponding 3σ upper limit on the 44Ti line flux amounts to 1.5 × 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2014
- DOI:
- 10.1088/0004-637X/789/2/123
- arXiv:
- arXiv:1405.6463
- Bibcode:
- 2014ApJ...789..123W
- Keywords:
-
- cosmic rays;
- gamma rays: ISM;
- ISM: supernova remnants;
- supernovae: individual: Tycho;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 15 pages, 4 figures, accepted for publication in ApJ