The first Fermi pulsar with an X-ray spectral feature

Analysis of the first 20ks Chandra observation of the bright radioquiet Fermipulsar J0633+0632 reveals an absorption feature in its spectrum near 0.8 keV.Besides that, it is likely the coldest neutron star at the neutrino coolingstage. However, a low number of source counts in Chandra data does not allow toconstrain the line shape and the thermal continuum origin. We propose deepobservations with XMMNewton to establish the absorption feature shape, toexplore the continuum, and to search for Xray pulsations with the pulsarperiod. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]