* Astronomy

Title: AX J1910.7+0917: the slowest X-ray pulsar
Author: L. Sidoli (1), G.L. Israel (2), P. Esposito (3), G.A. Rodriguez Castillo (2), K. Postnov (4,5) ((1)-INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Milano, Italy, (2)-INAF, Osservatorio Astronomico di Roma, Monteporzio Catone, Italy, (3)-Anton Pannekoek Institute for Astronomy, University of Amsterdam, The Netherlands, (4)-Moscow Lomonosov State University, Faculty of Physics, Moscow, Russia, (5)-Moscow Lomonosov State University, Sternberg Astronomical Institute, Moscow, Russia)

Pulsations from the high mass X-ray binary AXJ1910.7+0917 were discovered during Chandra observations performed in 2011 (Israel et al. 2016). We report here more details on this discovery and discuss the source nature. The period of the X-ray signal is P=36200±110s, with a pulsed fraction, PF, of 63±4%. Given the association with a massive B-type companion star, we ascribe this long periodicity to the rotation of the neutron star, making AXJ1910.7+0917 the slowest known X-ray pulsar. We report also on the spectroscopy of XMM-Newton observations that serendipitously covered the source field, resulting in an highly absorbed (column density almost reaching 1e23cm-2), power law X-ray spectrum. The X-ray flux is variable on a timescale of years, spanning a dynamic range >60. The very long neutron star spin period can be explained within a quasi-spherical settling accretion model, that applies to low luminosity, wind-fed, X-ray pulsars.

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