Discovery of Two Millisecond Pulsars in Fermi Sources with the Nançay Radio Telescope
Abdo, A. A.; Ballet, J.; Camilo, F.; Cheung, C. C.; Dumora, D.; Grove, J. E.; Guillemot, L.; Harding, A. K.; Johnson, T. J.; Michelson, P. F.; Parent, D.; Ransom, S. M.; Ray, P. S.; Romani, R. W.; Saz Parkinson, P. M.; Smith, D. A.; Thompson, D. J.; Venter, C.; Wolff, M. T.; Wood, K. S.; Ferrara, E. C.; Kramer, M.; Johnston, S.; Theureau, G.; Lyne, A. G.; Stappers, B. W.; Freire, P. C. C.; Keith, M.; Weltevrede, P.; Donato, D.; Cognard, I.; Desvignes, G.
France, Germany, United States, South Africa, Australia, United Kingdom
Abstract
We report the discovery of two millisecond pulsars in a search for radio pulsations at the positions of Fermi-Large Area Telescope sources with no previously known counterparts, using the Nançay Radio Telescope. The two millisecond pulsars, PSRs J2017+0603 and J2302+4442, have rotational periods of 2.896 and 5.192 ms and are both in binary systems with low-eccentricity orbits and orbital periods of 2.2 and 125.9 days, respectively, suggesting long recycling processes. Gamma-ray pulsations were subsequently detected for both objects, indicating that they power the associated Fermi sources in which they were found. The gamma-ray light curves and spectral properties are similar to those of previously detected gamma-ray millisecond pulsars. Detailed modeling of the observed radio and gamma-ray light curves shows that the gamma-ray emission seems to originate at high altitudes in their magnetospheres. Additionally, X-ray observations revealed the presence of an X-ray source at the position of PSR J2302+4442, consistent with thermal emission from a neutron star. These discoveries along with the numerous detections of radio-loud millisecond pulsars in gamma rays suggest that many Fermi sources with no known counterpart could be unknown millisecond pulsars.