Cooling of hybrid neutron stars and hypothetical self-bound objects with superconducting quark cores

Free access article

Issue		A&A Volume 368, Number 2, March III 2001


Page(s)		561 - 568
Section		Formation, structure and evolution of stars
DOI		http://dx.doi.org/10.1051/0004-6361:20010005

A&A 368, 561-568 (2001)
DOI: 10.1051/0004-6361:20010005

Cooling of hybrid neutron stars and hypothetical self-bound objects with superconducting quark cores

D. Blaschke^{1, 2}, H. Grigorian^{1, 3} and D. N. Voskresensky⁴

¹ Fachbereich Physik, Universität Rostock, Universitätsplatz 1, 18051 Rostock, Germany
² European Centre for Theoretical Studies ECT^*, Villa Tambosi, Strada delle Tabarelle 286, 38050 Villazzano (Trento), Italy
³ Department of Physics, Yerevan State University, Alex Manoogian Str. 1, 375025 Yerevan, Armenia
e-mail: hovik@darss.mpg.uni-rostock.de
⁴ Moscow Institute for Physics and Engineering, Kashirskoe shosse 31, 115409 Moscow, Russia Gesellschaft für Schwerionenforschung GSI, Planckstrasse 1, 64291 Darmstadt, Germany
e-mail: D.Voskresensky@gsi.de

(Received 19 September 2000 / Accepted 12 December 2000)

Abstract
We study the consequences of superconducting quark cores (with color-flavor-locked phase as representative example) for the evolution of temperature profiles and cooling curves in quark-hadron hybrid stars and in hypothetical self-bound objects having no hadron shell (quark core neutron stars). The quark gaps are varied from 0 to $\Delta_q =50$ MeV. For hybrid stars we find time scales of $1\div5$ , $5\div10$ and $50\div100$ years for the formation of a quasistationary temperature distribution in the cases $\Delta_q =0$ , 0.1 MeV and $\ga$ 1 MeV, respectively. These time scales are governed by the heat transport within quark cores for large diquark gaps ( $\Delta \ga$ 1 MeV) and within the hadron shell for small diquark gaps ( $\Delta \la 0.1$ MeV). For quark core neutron stars we find a time scale $\simeq$ 300 years for the formation of a quasistationary temperature distribution in the case $\Delta \ga$ 10 MeV and a very short one for $\Delta \la$ 1 MeV. If hot young compact objects will be observed they can be interpreted as manifestation of large gap color superconductivity. Depending on the size of the pairing gaps, the compact star takes different paths in the ${log}(T_{\rm s})$ vs. log(t) diagram where $T_{\rm s}$ is the surface temperature. Compared to the corresponding hadronic model which well fits existing data the model for the hybrid neutron star (with a large diquark gap) shows too fast cooling. The same conclusion can be drawn for the corresponding self-bound objects.

Key words: dense matter -- stars: interiors -- stars: evolution -- stars: neutron

Offprint request: D. Blaschke, blaschke@darss.mpg.uni-rostock.de

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