The > 100Â GeV \gamma -ray source , HESS J1713 - 381 , apparently associated with the shell-type supernova remnant ( SNR ) CTB 37B , was discovered using H.E.S.S .
in 2006 .
X-ray follow-up observations with Chandra were performed in 2007 with the aim of identifying a synchrotron counterpart to the TeV source and/or thermal emission from the SNR shell .
These new Chandra data , together with additional TeV data , allow us to investigate the nature of this object in much greater detail than was previously possible .
The new X-ray data reveal thermal emission from a \sim 4 ^ { \prime } region in close proximity to the radio shell of CTB 37B .
The temperature of this emission implies an age for the remnant of \sim 5000 years and an ambient gas density of \sim 0.5 cm ^ { -3 } .
Both these estimates are considerably uncertain due to the asymmetry of the SNR and possible modifications of the kinematics due to efficient cosmic ray ( CR ) acceleration .
A bright ( \approx 7 \times 10 ^ { -13 } erg cm ^ { -2 } s ^ { -1 } ) and unresolved ( < 1 \arcsec ) source ( CXOU J171405.7 - 381031 ) with a soft ( \Gamma \approx 3.3 ) non-thermal spectrum is also detected in coincidence with the radio shell .
Absorption indicates a column density consistent with the thermal emission from the shell suggesting a genuine association rather than a chance alignment .
The observed TeV morphology is consistent with an origin in the complete shell of CTB 37B .
The lack of diffuse non-thermal X-ray emission suggests an origin of the \gamma -ray emission via the decay of neutral pions produced in interactions of protons and nuclei , rather than inverse Compton ( IC ) emission from relativistic electrons .