Discovery of a Slow X-Ray Pulsator, AX J1740.1-2847, in the Galactic Center Region

We report the discovery of an X-ray pulsar, AX J1740.1–2847, from the Galactic center region. This source was found as a faint hard X-ray object on 1998 September 7–8 with the ASCA Galactic center survey observation. Then, coherent pulsations of P = 729± 14 s period were detected. The X-ray spectrum is described by a flat power-law of ∼ 0.7 photon index. The large absorption column of log NH ∼ 22.4 cm⁻² indicates that AX J1740.1–2847 is a distant source, larger than 2.4 kpc, and possibly near to the Galactic center region. The luminosity in the 2–10 keV band is larger than 2.5×10³³ erg s⁻¹, or likely to be 3.2×10³⁴ erg s⁻¹ at the Galactic-center distance. Although the slow-pulse period does not discriminate whether AX J1740.1–2847 is a white dwarf or neutron-star binary, the flat power-law and moderate luminosity strongly favor a neutron-star binary.