X-Ray Studies of HESS J1837-069 with Suzaku and ASCA: a VHE Gamma-Ray Source Originated from the Pulsar Wind Nebula

Abstract

We present ASCA and Suzaku studies of the TeV source HESS J1837-069, which has not been identified in other wavelengths. We confirm the presence of two X-ray sources in the Suzaku XIS image, AX J1838.0-0655 and AX J1837.3-0652, near both ends of the elongated TeV emission region. The XIS spectra of the two sources were reproduced by an absorbed power-law model, whose parameters are all consistent with those determined by the ASCA data. Recently, 70.5ms X-ray pulsation has been detected with RXTE in the sky region including HESS J1837-069 (Gotthelf & Halpern 2008, ApJ, 681, 515). Using the ASCA GIS data, which has both timing and imaging capabilities, we identified the pulsation source as AX J1838.0-0655. The pulse periods determined by ASCA and Suzaku, and that reported with RXTE indicate steady spin-down at dot{P} = 4.917(4) × 10^-14ss^-1. These results suggest that AX J1838.0-0655 is an intrinsically stable source, and presumably a pulsar wind nebula (PWN). We discuss the possibility that AX J1838.0-0655 is associated with HESS J1837-069 and the VHE γ-ray emission is originated from the PWN.