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Title: TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS

Abstract

Strange stars are one of the possible compact stellar objects that can form after a supernova collapse. We consider a model of a strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting (CCSC) layer. These two phases constitute the quarksphere, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming an ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming an electron layer a few hundred fermi thick separating the ionic crust from the underlying quark matter. The ionic matter and the CCSC matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than 10{sup −4} of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy CCSC crust layer will absorb only a smallmore » fraction of the glitch energy, leading to a large-amplitude torsional oscillation of the ionic crust. The maximum stress generated by the torsional oscillation is located inside the ionic crust and is very close to the star’s surface. This peculiar behavior leads to a much easier crust cracking than in standard neutron stars.« less

Authors:
; ; ; ;  [1]
  1. INFN, Laboratori Nazionali del Gran Sasso, Via G. Acitelli, 22, I-67100 Assergi (AQ) (Italy)
Publication Date:
OSTI Identifier:
22521770
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 815; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC ELECTRONS; ELECTRIC FIELDS; FLAVOR MODEL; GRAVITATIONAL COLLAPSE; LAYERS; NEUTRON STARS; NUCLEAR MATTER; OSCILLATIONS; QUARK MATTER; STAR MODELS; STRESSES; SUPERNOVAE; SURFACES

Citation Formats

Mannarelli, Massimo, Pagliaroli, Giulia, Parisi, Alessandro, Pilo, Luigi, and Tonelli, Francesco, E-mail: massimo@lngs.infn.it. TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/815/2/81.
Mannarelli, Massimo, Pagliaroli, Giulia, Parisi, Alessandro, Pilo, Luigi, & Tonelli, Francesco, E-mail: massimo@lngs.infn.it. TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS. United States. doi:10.1088/0004-637X/815/2/81.
Mannarelli, Massimo, Pagliaroli, Giulia, Parisi, Alessandro, Pilo, Luigi, and Tonelli, Francesco, E-mail: massimo@lngs.infn.it. Sun . "TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS". United States. doi:10.1088/0004-637X/815/2/81.
@article{osti_22521770,
title = {TORSIONAL OSCILLATIONS OF NONBARE STRANGE STARS},
author = {Mannarelli, Massimo and Pagliaroli, Giulia and Parisi, Alessandro and Pilo, Luigi and Tonelli, Francesco, E-mail: massimo@lngs.infn.it},
abstractNote = {Strange stars are one of the possible compact stellar objects that can form after a supernova collapse. We consider a model of a strange star having an inner core in the color-flavor locked phase surmounted by a crystalline color superconducting (CCSC) layer. These two phases constitute the quarksphere, which we assume to be the largest and heaviest part of the strange star. The next layer consists of standard nuclear matter forming an ionic crust, hovering on the top of the quarksphere and prevented from falling by a strong dipolar electric field. The dipolar electric field arises because quark matter is confined in the quarksphere by the strong interaction, but electrons can leak outside forming an electron layer a few hundred fermi thick separating the ionic crust from the underlying quark matter. The ionic matter and the CCSC matter constitute two electromagnetically coupled crust layers. We study the torsional oscillations of these two layers. Remarkably, we find that if a fraction larger than 10{sup −4} of the energy of a Vela-like glitch is conveyed to a torsional oscillation, the ionic crust will likely break. The reason is that the very rigid and heavy CCSC crust layer will absorb only a small fraction of the glitch energy, leading to a large-amplitude torsional oscillation of the ionic crust. The maximum stress generated by the torsional oscillation is located inside the ionic crust and is very close to the star’s surface. This peculiar behavior leads to a much easier crust cracking than in standard neutron stars.},
doi = {10.1088/0004-637X/815/2/81},
journal = {Astrophysical Journal},
number = 2,
volume = 815,
place = {United States},
year = {Sun Dec 20 00:00:00 EST 2015},
month = {Sun Dec 20 00:00:00 EST 2015}
}
  • The gravity-mode (g-mode) eigenfrequencies of newly born strange quark stars (SQSs) and neutron stars (NSs) are studied. It is found that the eigenfrequencies in SQSs are much lower than those in NSs by almost 1 order of magnitude, since the components of a SQS are all extremely relativistic particles while nucleons in a NS are nonrelativistic. We therefore propose that newly born SQSs can be distinguished from the NSs by detecting the eigenfrequencies of the g-mode pulsations of supernovae cores through gravitational radiation by LIGO-class detectors.
  • We determine all possible equilibrium sequences of compact strange-matter stars with nuclear crusts, which range from massive strange stars to strange white dwarf{endash}like objects (strange dwarfs). The properties of such stars are compared with those of their nonstrange counterparts{emdash}neutron stars and ordinary white dwarfs. The main emphasis of this paper is on strange dwarfs, which we divide into two distinct categories. The first one consists of a core of strange matter enveloped within ordinary white dwarf matter. Such stars are hydrostatically stable with or without the strange core and are therefore referred to as {open_quote}{open_quote}trivial{close_quote}{close_quote} strange dwarfs. This is differentmore » for the second category which forms an entirely new class of dwarf stars that contain nuclear material up to 4{times}10{sup 4} times denser than in ordinary white dwarfs of average mass, {ital M}{approximately}0.6 {ital M}{sub {circle_dot}}, and still about 400 times denser than in the densest white dwarfs. The entire family of such dwarfs, denoted {ital dense strange dwarfs}, owes its hydrostatic stability to the strange core. A striking features of strange dwarfs is that the entire sequence from the maximum-mass strange star to the maximum-mass strange dwarf is stable to radial oscillations. The minimum-mass star is only conditionally stable, and the sequences on both sides are stable. Such a stable, continuous connection does not exist between ordinary white dwarfs and neutron stars, which are known to be separated by a broad range of unstable stars. We find an expansive range of very low mass (planetary-like) strange-matter stars (masses even below 10{sup {minus}4} {ital M}{sub {circle_dot}} are possible) that arise as natural dark-matter candidates, which if abundant enough in our Galaxy, should be seen in the gravitational microlensing searches that are presently being performed. {copyright} {ital 1995 The American Astronomical Society.}« less
  • We study the bulk viscosity of the strange quark matter in the density-dependent quark mass model (DDQM) under the background of self-consistent thermodynamics. The correct formula of the viscosity is derived. We also find that the viscosity in the DDQM is larger by two to three orders of magnitude than that in MIT bag model. We calculate the damping time scale due to the coupling of the viscosity and r mode. The numerical results show that the time scale cannot be shorter than 10{sup -1} s.
  • Strange quark matter could be found in the core of neutron stars or forming strange quark stars. As is well known, these astrophysical objects are endowed with strong magnetic fields that affect the microscopic properties of matter and modify the macroscopic properties of the system. In this article we study the role of a strong magnetic field in the thermodynamical properties of a magnetized degenerate strange quark gas, taking into account {beta}-equilibrium and charge neutrality. Quarks and electrons interact with the magnetic field via their electric charges and anomalous magnetic moments. In contrast to the magnetic field value of 10{supmore » 19} G, obtained when anomalous magnetic moments are not taken into account, we find the upper bound B < or approx. 8.6x10{sup 17} G, for the stability of the system. A phase transition could be hidden for fields greater than this value.« less