A detailed X-ray investigation of PSR J2021+4026 and $\gamma$-Cygni supernova remnant

Abstract

We have investigated the field around the radio-quiet $\gamma$-ray pulsar, PSR J2021+4026, with a ~140 ks XMM-Newton observation and a ~56 ks archival Chandra data. Through analyzing the pulsed spectrum, we show that the X-ray pulsation is purely thermal in nature which suggests the pulsation is originated from a hot polar cap with $T\sim 3\times 10^6$ K on the surface of a rotating neutron star. On the other hand, the power-law component that dominates the pulsar emission in the hard band is originated from off-pulse phases, which possibly comes from a pulsar wind nebula. In re-analyzing the Chandra data, we have confirmed the presence of bow-shock nebula which extends from the pulsar to west by ~10 arcsec. The orientation of this nebular feature suggests that the pulsar is probably moving eastward which is consistent with the speculated proper motion by extrapolating from the nominal geometrical center of the supernova remnant (SNR) G78.2+2.1 to the current pulsar position. For G78.2+2.1, our deep XMM-Newton observation also enables a study of the central region and part of the southeastern region with superior photon statistics. The column absorption derived for the SNR is comparable with that for PSR J2021+4026, which supports their association. The remnant emission in both examined regions are in an non-equilibrium ionization state. Also, the elapsed time of both regions after shock-heating is apparently shorter than the Sedov age of G78.2+2.1. This might suggest the reverse shock has reached the center not long ago. Apart from PSR J2021+4026 and G78.2+2.1, we have also serendipitously detected an X-ray flash-like event XMM J202154.7+402855 from this XMM-Newton observation.

45 pages, 10 figures, 2 tables, accepted for publication in ApJ

References in corpus (8)

• Fermi Large Area Telescope Bright Gamma-ray Source List
• Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT
• Precise Gamma-Ray Timing and Radio Observations of 17 Fermi Gamma-Ray Pulsars
• A 200-s Quasi-Periodicity Following the Tidal Disruption of a Star by a Dormant Black Hole
• X-ray emission properties of the old pulsar PSR B2224+65
• Multiwavelength properties of a new Geminga-like pulsar: PSR J2021+4026
• Resolving the bow-shock nebula around the old pulsar PSR B1929+10 with multi-epoch Chandra observations
• Identification campaign of supernova remnant candidates in the Milky Way. II. X-ray studies of G38.7-1.4

Cited by in corpus (11)

• The FAST Galactic Plane Pulsar Snapshot survey: I. Project design and pulsar discoveries
• The gas-to-extinction ratio and the gas distribution in the Galaxy
• The Inner Accretion Flow in the Resurgent Seyfert-1.2 AGN Mrk 817
• Observational constraints on the maximum energies of accelerated particles in supernova remnants: low maximum energies and a large variety
• Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties
• Study of the GeV to TeV morphology of the $\gamma$-Cygni SNR (G78.2+2.1) with MAGIC and Fermi-LAT
• A search for radio pulsars in five nearby supernova remnants
• Strongly pulsed thermal X-rays from a single extended hot spot on PSR J2021+4026
• AGILE study of the gamma-ray emission from the SNR G78.2+2.1 (Gamma Cygni)
• Search for periodic emission of five gamma-ray pulsars at the frequency of 111 MHz
• Chandra Proper Motions and Milliarcsecond Astrometry of Nineteen Pulsars