2013/04/30 by J. A. Pons, Jose A. Pons, Daniele Viganò +2 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #High-pressure geophysics and materials #Pulsars and Gravitational Waves Research #astro-ph.HE #astro-ph.SR #nucl-th
paper · pdf · doi:10.1038/nphys2640
published as Nature Physics, 9, 431-434 (2013) · 18 pages (4 in the Nature format) and 3 figures
openalex publication_date 2013/06/07 · arxiv created 2013/11/12 · arxiv updated 2013/11/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The lack of X-ray pulsars with spin periods > 12 s raises the question of where the population of evolved high magnetic field neutron stars has gone. Unlike canonical radio pulsars, X-ray pulsars are not subject to physical limits to the emission mechanism nor observational biases against the detection of sources with longer periods. Here we show that a highly resistive layer in the innermost part of the crust of neutron stars naturally limits the spin period to a maximum value of about 10-20 s. This highly resistive layer is expected if the inner crust is amorphous and heterogeneous in nuclear charge, possibly due to the existence of a nuclear pasta phase. Our findings suggest that the maximum period of isolated X-ray pulsars can be the first observational evidence of an amorphous inner crust, which properties can be further constrained by future X-ray timing missions combined with more detailed models.