The Variable Pulsar Wind Nebula of PSR J1809–1917

Abstract

Abstract PSR J1809–1917 is a young (τ = 51 kyr) energetic ( erg s−1) radio pulsar powering a pulsar wind nebula (PWN). We report on the results of three Chandra X-ray Observatory observations that show that the PWN consists of a small (∼20″) bright compact nebula (CN) and faint extended emission seen up to 2′ from the pulsar. The CN is elongated in the northeast–southwest direction and exhibits morphological and flux variability on a timescale of a few months. We also find evidence of small arcsecond-scale jets extending from the pulsar along the same direction, and exhibiting a hard power-law (PL) spectrum with photon index Γjet = 1.2 ± 0.1. The more extended emission and CN share the same symmetry axis, which is also aligned with the direction toward the TeV γ-ray source HESS J1809–193, supporting their association. The spectrum of the extended nebula (EN) fits an absorbed PL with about the same slope as that of the CN, ΓCN ≈ ΓEN = 1.55 ± 0.09; no spectral changes across the EN’s 2 pc extent are seen. The total PWN 0.5–8 keV luminosity is L PWN ≈ 9 × 1032 erg s−1, about half of which is due to the EN.