Durabiity of Neutron Star Crust

Abstract

How long do neutron star mountains last? The durability of elastically deformed crust is important for neutron star physics including pulsar glitches, emission of gravitational waves from static mountains, and flares from star quakes. The durability is defined by the strength properties of the Yukawa crystals of ions, which make up the crust. In this paper we extend our previous results [Mon. Not. R. Astron. Soc. 407, L54 (2010)] and accurately describe the dependence of the durability on crust composition (which can be reduced to the dependence on the screening length λ of the Yukawa potential). We perform several molecular dynamics simulations of crust breaking and describe their results with a phenomenological model based on the kinetic theory of strength. We provide an analytical expression for the durability of neutron star crust matter for different densities, temperatures, stresses, and compositions. This expression can also be applied to estimate durability of Yukawa crystals in other systems, such as dusty plasmas in the laboratory (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Breaking properties of neutron star crust

“…We point out that the maximum deformation is typically smaller for a contraction of the lattice, than for an elongation. Also, typical maximum contraction deformation is about 5%, which is a factor of two lower than the breaking strain for the shear deformation, obtained by Horowitz & Kadau (2009) and Chugunov & Horowitz (2010. Our results clearly demonstrate that the Tresca and von Misses failure criteria are not valid for perfect Coulomb lattice in NS crust.…”

“…In particular, it is known to predict elastic properties of the crust with reasonable accuracy (Baiko 2011(Baiko , 2015. Chugunov & Horowitz (2012) have analysed effects of electron screening on the breaking stress for the shear deformation and have demonstrated that screening reduced strength, but not very much. Thus, we expect that an accurate treatment of electron screening can only reduce maximum pressure anisotropy.…”

“…maximum stress, which the elastically deformed crustal material can withstand). If the crust is indeed as strong as it is suggested by molecular dynamic (MD) sim-⋆ E-mail:baiko@astro.ioffe.ru † E-mail:andr@astro.ioffe.ru ulations (Horowitz & Kadau 2009;Chugunov & Horowitz 2010, the GW emission can be poweful enough to be detectable by existing GW observatories (Johnson-McDaniel 2013;Caplan & Horowitz 2017). Haskell & Patruno (2017) have recently suggested that this GW emission could be responsible for observed spin-down during the accreting phase of PSR J1023+0038.…”

“…Thus, an accurate knowledge of the crust strength is fundamental for NS physics and in this paper we analyse it, paying special attention to its anisotropy. Previous works in this field explored a shear deformation by MD simulation (Horowitz & Kadau 2009;Chugunov & Horowitz 2010Hoffman & Heyl 2012) and volume-conserving crystal stretching in two highly symmetric directions semianalytically (Baiko & Kozhberov 2017; Paper 1). Here we apply the approach proposed in the latter work to study stretching in arbitrary directions.…”

Pasta nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium

“…On rapidly rotating stars these mountains are energetic sources of gravitational wave radiation [14]. Finally the pasta breaking strain is relevant for crust breaking models of star quakes and magnetar giant flares [15].…”