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

• Published in: Publications of the Astronomical Society of Japan Vol. 61; no. sp1; pp. S183 - S187
• Main Authors: Anada, Takayasu, Ebisawa, Ken, Dotani, Tadayasu, Bamba, Aya
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford University Press 30.01.2009
• Subjects: stars: neutron; ISM: individual (HESS J1837–069); X-rays: individual (AX J1838.0-0655, AX J1837.3-0652)
• ISSN: 0004-6264; 2053-051X
• DOI: 10.1093/pasj/61.sp1.S183

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, 70.5 ms 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) $\times$ 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.