X-ray studies of HESS J1837--069 with Suzaku and ASCA: a VHE gamma-ray source originated from the pulsar wind nebula

TL;DR

This study uses ASCA and Suzaku X-ray observations to analyze the TeV gamma-ray source HESS J1837--069, identifying a pulsar wind nebula and pulsar, and suggesting the gamma-ray emission originates from the PWN.

Contribution

The paper confirms the association of the X-ray source AX J1838.0--0655 with a pulsar wind nebula and links it to the TeV gamma-ray source HESS J1837--069, providing new insights into its nature.

Findings

AX J1838.0--0655 is identified as a pulsar wind nebula.

The pulsar shows steady spin-down with period derivative $ imes 10^{-14}$ s s$^{-1}$.

The VHE gamma-ray emission is likely originating from the PWN.

Abstract

We present the ASCA and Suzaku studies of the TeV source HESS J1837--069, which has not been identified in other wave-lengths. 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 are reproduced by an absorbed power-law model, whose parameters are all consistent with those determined by the ASCA data. Recently, 70.5 ms X-ray pulsation has been detected with RXTE in the sky region including HESS J1837--069 (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 $\dot{P} = 4.917(4) \times 10^{-14}$ s s$^{-1}$. 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 gamma-ray emission is originated from the PWN.