Letter to the Editor

INTEGRAL high energy observations of 2S 0114+65

¹ LUTh, Observatoire de Paris, 92195 Meudon Cedex, France e-mail: erin.bonning@obspm.fr
² CEA Saclay, DSM/DAPNIA/Service d'Astrophysique (CNRS FRE 2591), 91191 Gif-sur-Yvette, France

Received: 11 March 2005
Accepted: 28 April 2005

Abstract

We report the first INTEGRAL timing and spectral analysis of the high mass X-ray binary source 2S 0114+65 at high energies (5–100 keV). The pulse period was found at 2.668 h with a high pulsed fraction, ~80% in both the 20–40 keV and 40–80 keV energy bands. The spin-up trend over ~8 years was measured to be   10^-7 s s^-1. The hard X-ray spectrum obtained with JEM-X/ISGRI is well described by a high energy exponential cut-off power law model where the estimated luminosity is 1.8  10³⁶ erg s^-1 in the 5–100 keV energy band, for a source distance of 7.2 kpc. We tentatively identify a cyclotron resonance scattering feature at ~22 keV with one harmonic, implying a magnetic field of ~2.5  10¹² G.