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Title: Inhomogeneous color superconductivity and the cooling of compact stars

Abstract

In this talk I discuss the inhomogeneous (LOFF) color superconductive phases of Quantum Chromodynamics (QCD). In particular, I show the effect of a core of LOFF phase on the cooling of a compact star.

Authors:
 [1];  [2]
  1. Dipartimento di Fisica, Universita degli Studi di Bari (Italy)
  2. (Italy)
Publication Date:
OSTI Identifier:
21056892
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 892; Journal Issue: 1; Conference: QCHS7: 7. conference on quark confinement and the hadron spectrum, Ponta Delgada, Acores (Portugal), 2-7 Sep 2006; Other Information: DOI: 10.1063/1.2714452; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLOR MODEL; COOLING; QUANTUM CHROMODYNAMICS; STAR EVOLUTION; STARS; SUPERCONDUCTIVITY

Citation Formats

Ruggieri, M., and Istituto Nazionale di Fisica Nucleare, Sezione di Bari. Inhomogeneous color superconductivity and the cooling of compact stars. United States: N. p., 2007. Web. doi:10.1063/1.2714452.
Ruggieri, M., & Istituto Nazionale di Fisica Nucleare, Sezione di Bari. Inhomogeneous color superconductivity and the cooling of compact stars. United States. doi:10.1063/1.2714452.
Ruggieri, M., and Istituto Nazionale di Fisica Nucleare, Sezione di Bari. Tue . "Inhomogeneous color superconductivity and the cooling of compact stars". United States. doi:10.1063/1.2714452.
@article{osti_21056892,
title = {Inhomogeneous color superconductivity and the cooling of compact stars},
author = {Ruggieri, M. and Istituto Nazionale di Fisica Nucleare, Sezione di Bari},
abstractNote = {In this talk I discuss the inhomogeneous (LOFF) color superconductive phases of Quantum Chromodynamics (QCD). In particular, I show the effect of a core of LOFF phase on the cooling of a compact star.},
doi = {10.1063/1.2714452},
journal = {AIP Conference Proceedings},
number = 1,
volume = 892,
place = {United States},
year = {Tue Feb 27 00:00:00 EST 2007},
month = {Tue Feb 27 00:00:00 EST 2007}
}
  • We discuss specific heat and neutrino emissivity due to direct Urca processes for quark matter in the color superconductive Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase of quantum chromodynamics. We assume that the three light quarks u, d, s are in a color and electrically neutral state and interact by a four-fermion Nambu-Jona-Lasinio coupling. We study a LOFF state characterized by a single plane wave for each pairing. From the evaluation of neutrino emissivity and fermionic specific heat, the cooling rate of simplified models of compact stars with a quark core in the LOFF state is estimated.
  • We present a new scenario for the cooling of compact stars considering the central source of Cassiopeia A (Cas A). The Cas A observation shows that the central source is a compact star that has high effective temperature, and it is consistent with the cooling without exotic phases. The observation also gives the mass range of M {>=} 1.5 M {sub Sun }, which may conflict with the current plausible cooling scenario of compact stars. There are some cooled compact stars such as Vela or 3C58, which can barely be explained by the minimal cooling scenario, which includes the neutrinomore » emission by nucleon superfluidity (PBF). Therefore, we invoke the exotic cooling processes, where a heavier star cools faster than lighter one. However, the scenario seems to be inconsistent with the observation of Cas A. Therefore, we present a new cooling scenario to explain the observation of Cas A by constructing models that include a quark color superconducting (CSC) phase with a large energy gap; this phase appears at ultrahigh density regions and reduces neutrino emissivity. In our model, a compact star has a CSC quark core with a low neutrino emissivity surrounded by high emissivity region made by normal quarks. We present cooling curves obtained from the evolutionary calculations of compact stars: while heavier stars cool slowly, and lighter ones indicate the opposite tendency without considering nucleon superfluidity. Furthermore, we show that our scenario is consistent with the recent observations of the effective temperature of Cas A during the last 10 years, including nucleon superfluidity.« less
  • We apply the recently developed logN-logS test of compact star cooling theories for the first time to hybrid stars with a color superconducting quark matter core. Although there is not yet a microscopically founded superconducting quark matter phase that would fulfill constraints from cooling phenomenology, we explore the hypothetical 2SC+X phase and show that the magnitude and density dependence of the X-gap can be chosen to satisfy a set of tests: temperature-age (T-t), the brightness constraint, logN-logS, and the mass spectrum constraint. The latter test appears as a new conjecture from the present investigation.
  • It has been suggested that quark matter is superfluid (superconducting) at the high densities and/or temperatures characteristic of compact star interiors. We present the first calculations of compact star cooling including this phase, showing that the cooling behavior could be dramatically changed with respect to former studies including a normal quark core. Particularly, we find that some of the presented scenarios tend to be closer to the observational data and open the possibility of subsequently modeling the histories of all known young and medium-aged (i.e., without significant reheating) pulsars without having to postulate any fundamental difference between them. Moreover, improvedmore » observations might allow an astrophysical determination of the quark-matter critical temperature.« less
  • We investigate neutral quark matter with homogeneous and inhomogeneous color condensates at finite temperature in the frame of an extended NJL model. By calculating the Meissner masses squared and gap susceptibility, the uniform color superconductor is stable only in a temperature window close to the critical temperature and becomes unstable against LOFF phase, mixed phase and gluonic phase at low temperatures. The introduction of the inhomogeneous phases leads to disappearance of the strange intermediate temperature 2SC/g2SC and changes the phase diagram of neutral dense quark matter significantly.