Detection of X-Ray Emission from the Unidentified TeV Gamma-Ray Source TeV J2032+4130

Abstract

We observed the first unidentified TeV $\gamma$ -ray source TeV J2032 $+$ 4130 with Suzaku. Owing to Suzaku's high sensitivity for the detection of diffuse X-ray emission, we found two small structures in the TeV emitting region. One of them is coincident with a $\gamma$ -ray pulsar, PSR J2032 $+$ 4127, which was discovered by the Fermi Gamma-ray Space Telescope. By subtracting the contribution of point sources estimated by Chandra data, we obtained the diffuse X-ray spectrum. The X-ray spectrum can be reproduced by a power-law model with a photon index of $\sim\ $ 2, and an X-ray flux of 2 $\times$ 10 $^{-13}\ $ erg s $^{-1}\ $ cm $^{-2}$ . The ratio of the $\gamma$ -ray flux to the X-ray flux is about 10. If the origin of the TeV $\gamma$ -rays is inverse Compton scattering of the microwave background by high-energy electrons, the ratio corresponds to a magnetic field strength of $\sim\ $ 1 $\ \mu$ G. However, the smaller size of the X-ray emission than that of the TeV emission suggests that the energy loss of the electrons can explain the large ratio of the $\gamma$ -ray flux with a reasonable magnetic field strength of a few microgauss.