2025/07/17 by Zhang, Xiying, Bordas, Pol, Safi-Harb, Samar +1
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2507.13278
We report on the results of a comprehensive analysis of X-ray observations carried out with Chandra, XMM-Newton and NuSTAR of the pulsar wind nebula (PWN) associated with PSR B1853+01, located inside the W44 supernova remnant (SNR). Previous X-ray observations unveiled the presence of a fast-moving pulsar, PSR B1853+01, located at the southern edge of the W44 thermal X-ray emission region, as well as an elongated tail structure trailing the pulsar. Our analysis reveals, in addition, the presence of an ``outflow'' feature ahead of the pulsar extending for about 1 \arcmin (∼ 1.0 pc at the distance of 3.2 kpc). At larger scales, the entire PWN seems to be surrounded by a faint, diffuse X-ray emission structure. The southern part of this structure displays the same unusual morphology as the ``outflow'' feature ahead of the pulsar, and extends along ∼ 6 \arcmin (∼ 5 pc) in the direction of the pulsar proper motion. In this report, a spatially-resolved spectral analysis for the different extended regions around PSR B1853+01 is carried out. For an updated value of the column density of 0.65+0.46-0.42 × 1022 ~\textrmcm-2, a power-law fit to the ``outflow'' region yields a spectral index Γ≈ 1.24+0.23-0.24, which is significantly harder than that of the pulsar (Γ≈ 1.87+0.48-0.43) and the pulsar tail (Γ≈ 2.01+0.39-0.38). We argue that both the ``outflow'' structure and the surrounding halo-like X-ray emission might be produced by high-energy particles escaping the PWN around PSR B1853+01, a scenario recently suggested also for other Bow-shock PWNe with jet-like structures and/or TeV halos.