Discovery of Diffuse Hard X-Ray Emission from the Vicinity of PSR J1648-4611 with Suzaku

TL;DR

This study reports the discovery of diffuse hard X-ray emission near PSR J1648-4611 with Suzaku, indicating a potential pulsar wind nebula and exploring its properties and relation to gamma-ray sources.

Contribution

First detection of diffuse hard X-ray emission around PSR J1648-4611, suggesting a pulsar wind nebula with properties distinct from expectations based on pulsar spin-down luminosity.

Findings

Diffuse hard X-ray emission suggests a pulsar wind nebula.

X-ray flux of Src A is larger than expected from the pulsar's spin-down power.

Identification of a soft X-ray source, Src B, with no known counterpart.

Abstract

We observed the pulsar PSR J1648-4611 with Suzaku. Two X-ray sources, Suzaku J1648-4610 (Src A) and Suzaku J1648-4615 (Src B), were found in the field of view. Src A is coincident with the pulsar PSR J1648-4611, which was also detected by the Fermi Gamma-ray Space Telescope. A hard-band image indicates that Src A is spatially extended. We found point sources in the vicinity of Src A by using a Chandra image of the same region, but the point sources have soft X-ray emission and cannot explain the hard X-ray emission of Src A. The hard-band spectrum of Src A can be reproduced by a power-law model with a photon index of 2.0^{+0.9}_{-0.7}. The X-ray flux in the 2-10 keV band is 1.4 \times 10^{-13} erg cm^{-2} s^{-1}. The diffuse emission suggests a pulsar wind nebula around PSR J1648-4611, but the luminosity of Src A is much larger than that expected from the spin-down luminosity of the pulsar. Parts of the very-high-energy gamma-ray emission of HESS J1646-458 may be powered by this pulsar wind nebula driven by PSR J1648-4611. Src B has soft emission, and its X-ray spectrum can be described by a power-law model with a photon index of 3.0^{+1.4}_{-0.8}. The X-ray flux in the 0.4-10 keV band is 6.4 \times 10^{-14} erg s^{-1} cm^{-2}. No counterpart for Src B is found in literatures.