Hard X-ray timing and spectral characteristics of the energetic pulsar PSR J0205+6449 in supernova remnant 3C 58

An RXTE PCA/HEXTE and XMM-Newton view on the 0.5–250 keV band

¹ SRON-Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands e-mail: L.M.Kuiper@sron.nl
² Astronomical Institute “Anton Pannekoek”, University of Amsterdam, PO Box 94249, 1090 GE, Amsterdam, The Netherlands e-mail: W.Hermsen@sron.nl
³ Dept. of Physics & Astronomy, University of Nigeria, Nsukka, Nigeria e-mail: johnson@hartrao.ac.za
⁴ Stanford University HEPL/KIPAC Physics, 382 via Pueblo Mall Stanford, 94305, USA e-mail: hartog@stanford.edu
⁵ Jodrell Bank Center for Astrophysics, School of Physics and Astronomy, The University of Manchester Manchester M13 9PL, UK e-mail: [andrew.lyne;ben.stappers]@manchester.ac.uk

Received: 11 December 2009
Accepted: 1 February 2010

Abstract

Context. PSR J0205+6449 is a young rotation-powered pulsar in SNR 3C 58. It is one of only three young (<10 000 year old) pulsars that have so far been detected in the radio and the classical X-ray bands, as well as at hard X-rays above 20 keV and at high-energy (>100 MeV) γ-rays. The other two young pulsars are the Crab and PSR B1509-58.

Aims. Our aim is to derive the timing and spectral characteristics of PSR J0205+6449 over the broad X-ray band from ~0.5 to ~270 keV.

Methods. We used all publicly available RXTE observations of PSR J0205+6449 to first generate accurate ephemerides over the period September 30, 2000–March 18, 2006. We then employed phase-folding procedures yielded pulse profiles using data from RXTE PCA and HEXTE, and XMM-Newton EPIC PN. All profiles were phase aligned with a radio profile derived from the Jodrell Bank Observatory data, and the time-averaged timing and spectral characteristics of the pulsed X-ray emission were derived.

Results. Our timing solutions are consistent with earlier results, but we detect sharper structures in the PCA X-ray profile. The X-ray pulse profile consists of two sharp pulses, separated in phase by 0.488 ± 0.002, that can be described by 2 asymmetric Lorentzians, each with the rising wing steeper than the trailing wing, and full-width-half-maximum 1.41 ± 0.05 ms and 2.35 ± 0.22 ms, respectively. For the second, weaker pulse we find an indication of a flux increase by a factor 2, about 3.5σ above the time-averaged value, over a two-week interval, during which its pulse shape did not change. The spectrum of the pulsed X-ray emission is non-thermal in origin, exhibiting a power-law shape with photon index Γ = 1.03 ± 0.02 over the energy band ~0.5 to ~270 keV. In the energy band covered with the PCA (3–30 keV), the spectra of the two pulses have the same photon index, namely, 1.04 ± 0.03 and 1.10 ± 0.08, respectively. Comparisons of the detailed timing and spectral characteristics of PSR J0205+6449 in the radio, hard X-ray, and gamma-ray bands with those of the Crab pulsar, PSR B1509-58 and the middle-aged Vela pulsar uncover more differences than similarities.