X-Ray Studies of the Extended TeV Gamma-Ray Source VER J2019+368

作者：Mizuno T^*; Tanaka N; Takahashi H; Katsuta J; Hayashi K; Yamazaki R

来源：Astrophysical Journal, 2017, 841(2): 104.

DOI：10.3847/1538-4357/aa7201

• cosmic rays
• gamma-rays: ISM
• ISM: individual objects (VER J2019+368)
• pulsars: individual (PSR J2021+3651)
• X-rays: ISM

This article reports the results of X-ray studies of the extended TeV gamma-ray source VER J2019+368. Suzaku observations conducted to examine properties of the X-ray pulsar wind nebula (PWN) around PSR J2021+3651 revealed that the western region of the X-ray PWN has a source extent of 15' x 10' with the major axis oriented to that of the TeV emission. The PWN-west spectrum was closely fitted by a power law for absorption at N(H) = (8.2(-1.1)(+1.13)) x 10(21) cm(-2) and a photon index of Gamma= 2.05 +/- 0.12, with no obvious change in the index within the X-ray PWN. The measured X-ray absorption indicates that the distance to the source is much less than the 10 kpc inferred by radio data. Aside from the PWN, no extended emission was observed around PSR. J2021+3651 even by Suzaku. Archival data from the XMM-Newton were also analyzed to complement the Suzaku observations, indicating that the eastern region of the X-ray PWN has a similar spectrum (N(H) = (7.5 +/- 0.9) x 10(21) cm(-2) and Gamma = 2.03 +/- 0.10) and source extent up to at least 12' along the major axis. The lack of significant change in the photon index and the source extent in X-ray are used to constrain the advection velocity or the diffusion coefficient for accelerated X-ray-producing electrons. A mean magnetic field of similar to 3 mu G is required to account for the measured X-ray spectrum and reported TeV gamma-ray spectrum. A model calculation of synchrotron radiation and inverse Compton scattering was able to explain similar to 80% of the reported TeV flux, indicating that the X-ray PWN is a major contributor of VER. J2019+368.

• 出版日期2017-6-1