X-ray Spectroscopy of the Highly Magnetized Pulsar PSR J1846-0258, its Wind Nebula and Hosting Supernova Remnant Kes 75

TL;DR

This study provides detailed broad-band X-ray spectroscopy of the Kes 75 supernova remnant, revealing the properties of its highly magnetized pulsar PSR J1846-0258, its pulsar wind nebula, and insights into the remnant's evolution and progenitor system.

Contribution

It offers the first comprehensive spectral analysis of Kes 75's components during a quiescent state and models the remnant's evolution, highlighting the pulsar's extreme magnetic field and potential magnetar transition.

Findings

Pulsar PSR J1846-0258 has a magnetic field of 4.9E13 G, the largest known for such objects.

The pulsar's spectrum is well-described by a power-law with photon index 1.24, with no evidence of magnetar-like non-thermal emission above 10 keV.

The PWN exhibits a photon index of 2.03, with a hard X-ray component above 10 keV attributed to dust-scattered emission.

Abstract

We present broad-band X-ray spectroscopy of the energetic components that make up the supernova remnant (SNR) Kesteven 75 using concurrent 2017 Aug 17-20 XMM-Newton and NuSTAR observations, during which the pulsar PSR J1846-0258 is found to be in the quiescent state. The young remnant hosts a bright pulsar wind nebula powered by the highly-energetic (Edot = 8.1E36 erg/s) isolated, rotation-powered pulsar, with a spin-down age of only P/2Pdot ~ 728 yr. Its inferred magnetic field (Bs = 4.9E13 G) is the largest known for these objects, and is likely responsible for intervals of flare and burst activity, suggesting a transition between/to a magnetar state. The pulsed emission from PSR J1846-0258 is well-characterized in the 2-50 keV range by a power-law model with photon index Gamma_PSR = 1.24+/-0.09 and a 2-10 keV unabsorbed flux of (2.3+/-0.4)E-12 erg/s/cm^2). We find no evidence for an additional non-thermal component above 10 keV in the current state, as would be typical for a magnetar. Compared to the Chandra pulsar spectrum, the intrinsic pulsed fraction is 71+/-16% in 2-10 keV band. A power-law spectrum for the PWN yields Gamma_PWN = 2.03+/-0.03 in the 1-55 keV band, with no evidence of curvature in this range, and a 2-10 keV unabsorbed flux (2.13+/-0.02)E-11 erg/s/cm^2. The NuSTAR data reveal evidence for a hard X-ray component dominating the SNR spectrum above 10 keV which we attribute to a dust-scattered PWN component. We model the dynamical and radiative evolution of the Kes 75 system to estimate the birth properties of the neutron star, the energetics of its progenitor, and properties of the PWN. This suggests that the progenitor of Kes 75 was originally in a binary system which transferred most its mass to a companion before exploding.