The Identification of the X-ray Counterpart to PSR J2021+4026

TL;DR

This paper identifies the probable X-ray counterpart to the gamma-ray pulsar PSR J2021+4026 using Chandra and Fermi data, providing positional, spectral, and flux ratio analyses that support a neutron star origin.

Contribution

It presents the first probable identification of the X-ray counterpart to PSR J2021+4026 with combined imaging and timing analysis, including precise localization and flux characterization.

Findings

X-ray source position coincides with gamma-ray pulsar within errors

X-ray spectrum suggests a combination of powerlaw and thermal components

No optical counterpart detected down to limiting magnitudes

Abstract

We report the probable identification of the X-ray counterpart to the gamma-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory ACIS and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20h21m30.733s, Decl. +40 deg 26 min 46.04sec (J2000) with an estimated uncertainty of 1.3 arsec combined statistical and systematic error. Moreover, both the X-ray to gamma-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' >23.0 mag and r' > 25.2mag. The source exhibits an X-ray spectrum with most likely both a powerlaw and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.