Expansion measurements of supernova remnant RX J1713.7−3946

Abstract

Abstract Supernova remnant (SNR) RX J1713.7−3946 is well known for its bright TeV gamma-ray emission with a shell-like morphology. Strong synchrotron X-ray emission dominates the total X-ray flux in SNR RX J1713.7−3946 and the X-ray morphology is broadly similar to the TeV gamma-ray appearance. The synchrotron X-ray and TeV gamma-ray brightness allows us to perform detailed analysis of the acceleration of TeV-scale particles in this SNR. To constrain the hydrodynamical evolution of RX J1713.7−3946, we have performed six observations of the northwestern (NW) shell with the Chandra X-ray Observatory from 2005 to 2011, and measured the proper motion by using these data and the first epoch observation taken in 2000. The blast-wave shock speed at the NW shell is measured to be (3900 ± 300)(d/ kpc) km s−1 with an estimated distance of d = 1 kpc, and the proper motions of other structures within the NW shell are significantly less than that. Assuming that the measured blast-wave shock speed is representative of the remnant's outer shock wave as a whole, we have confronted our measurements, as well as a recent detection of thermal X-ray lines, with the analytic solution of the hydrodynamical properties of SNRs. Our hydrodynamical analysis indicates that the age of the remnant is 1580–2100 yr, supporting the association with SN393. A model with supernova kinetic energy of E = 1051 erg, ejecta mass of Mej = 3 M⊙, and ambient density at the current blast wave location of n2 = 0.015 cm−3, provides a reasonable explanation for our measurements and previous findings at the X-ray and gamma-ray wavelengths. We find that the transition to the Sedov–Taylor phase is incomplete for any reasonable set of parameters, implying that the current maximum energy of accelerated protons in RX J1713.7−3946 would not correspond to the maximum attainable energy for this remnant.