Title: The soft gamma-ray timing- and spectral characteristics of millisecond pulsar PSR J0218+4232


Proposal ID: 0120062
Subject category: Compact Object
Principal investigator: Kuiper
Institute: SRON-Utrecht


Abstract

We propose to observe the remarkable millisecond pulsar (MSP) PSR J0218+4232 for 1000 ks with INTEGRAL to perform a detailed study of its soft gamma-ray characteristics. Our recent Chandra observations (0.08-10 keV) confirmed the alignment in absolute phase of the two established X-ray peaks with the peaks in the double peaked 100-1000 MeV gamma-ray profile. The hard spectrum at X-ray energies (photon index -0.6; 1.6-10 keV) combined with the soft spectrum at high-energy gamma-rays (index -2.6; 100-1000 MeV) indicates that the maximum luminosity is likely reached at MeV energies. INTEGRAL can uniquely establish the timing and spectral characteristics in detail in the soft gamma-ray range for this intriguing pulsar. Observations with INTEGRAL of PSR J0218+4232 provide the best way to investigate the production sites and processes in the magnetospheres of MSPs. Furthermore, a detailed understanding of the spectrum of PSR J0218+4232 can shed light on the origin of relatively strong (unidentified) high-energy gamma-ray sources without obvious X-ray counterparts.