X-Ray Characterization of the Pulsar PSR J1849−0001 and Its Wind Nebula G32.64+0.53 Associated with TeV Sources Detected by H.E.S.S., HAWC, Tibet ASγ, and LHAASO

Abstract

We report on the X-ray emission properties of the pulsar PSR J1849−0001 and its wind nebula (PWN), as measured by Chandra, XMM-Newton, NICER, Swift, and NuSTAR. In the X-ray data, we detected the 38 ms pulsations of the pulsar up to ∼60 keV with high significance. Additionally, we found that the pulsar's on-pulse spectral energy distribution displays significant curvature, peaking at ≈60 keV. Comparing the phase-averaged and on-pulse spectra of the pulsar, we found that the pulsar's off-pulse emission exhibits a spectral shape that is very similar to its on-pulse emission. This characterization of the off-pulse emission enabled us to measure the >10 keV spectrum of the faint and extended PWN using NuSTAR's off-pulse data. We measured both the X-ray spectrum and the radial profiles of the PWN’s brightness and photon index, and we combined these X-ray measurements with published TeV results. We then employed a multizone emission scenario to model the broadband data. The results of the modeling suggest that the magnetic field within the PWN is relatively low (≈7 μ G) and that electrons are accelerated to energies ≳400 TeV within this PWN. The electrons responsible for the TeV emission outside the X-ray PWN may propagate to ∼30 pc from the pulsar in ∼10 kyr.

Keywords

• Pulsars
• Pulsar wind nebulae
• Rotation powered pulsars
• High energy astrophysics
• Gamma-ray sources
• X-ray sources