Enhanced cooling of neutron stars via Cooper-pairing neutrino emission

Gusakov, M. E.; Kaminker, A. D.; Yakovlev, D. G.; Gnedin, Oleg Y.

doi:10.1051/0004-6361:20041006

Cited by 87 publications

(162 citation statements)

References 48 publications

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“…We also see the effect of superfluidity, i.e., faster cooling after neutrons become superfluid in the crust at early times and in the core at later times. These effects are strongest in regions near the critical temperatures, in accordance with the expectations from previous work (Gusakov et al 2004). …”

Section: Thermal Gradientssupporting

confidence: 92%

Buoyancy and g-modes in young superfluid neutron stars

Passamonti

Andersson

2015

Monthly Notices of the Royal Astronomical Society

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We consider the local dynamics of a realistic neutron star core, including composition gradients, superfluidity and thermal effects. The main focus is on the gravity g-modes, which are supported by composition stratification and thermal gradients. We derive the equations that govern this problem in full detail, paying particular attention to the input that needs to be provided through the equation of state and distinguishing between normal and superfluid regions. The analysis highlights a number of key issues that should be kept in mind whenever equation of state data is compiled from nuclear physics for use in neutron star calculations. We provide explicit results for a particular stellar model and a specific nucleonic equation of state, making use of cooling simulations to show how the local wave spectrum evolves as the star ages. Our results show that the composition gradient is effectively dominated by the muons whenever they are present. When the star cools below the superfluid transition, the support for g-modes at lower densities (where there are no muons) is entirely thermal. We confirm the recent suggestion that the g-modes in this region may be unstable, but our results indicate that this instability will be weak and would only be present for a brief period of the star's life. Our analysis accounts for the presence of thermal excitations encoded in entrainment between the entropy and the superfluid component. Finally, we discuss the complete spectrum, including the normal sound waves and, in superfluid regions, the second sound.

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Section: Thermal Gradientssupporting

confidence: 92%

Buoyancy and g-modes in young superfluid neutron stars

Passamonti

Andersson

2015

Monthly Notices of the Royal Astronomical Society

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“…Urca process [5,6]. A transition from the slow neutrino emission in low-mass NSs to a fast emission in massive NSs with increasing M occurs in medium-mass NSs; the mass range of medium-mass stars is model-dependent.…”

Section: Thermal States Of Soft X-ray Transientsmentioning

confidence: 99%

“…The first one is based on theory and observations of cooling isolated NSs (e.g., Refs. [4,5,6,7]). These studies, carried out over several decades, have constrained the properties of dense matter but have not solved the problem (Sect.…”

Section: Introductionmentioning

confidence: 99%

Pycnonuclear reactions in dense stellar matter

2005

Self Cite

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Abstract. We discuss pycnonuclear burning of highly exotic atomic nuclei in deep crusts of neutron stars, at densities up to 10 13 g cm −3 . As an application, we consider pycnonuclear burning of matter accreted on a neutron star in a soft X-ray transient (SXT, a compact binary containing a neutron star and a low-mass companion). The energy released in this burning, while the matter sinks into the stellar crust under the weight of newly accreted material, is sufficient to warm up the star and initiate neutrino emission in its core. The surface thermal radiation of the star in quiescent states becomes dependent of poorly known equation of state (EOS) of supranuclear matter in the stellar core, which gives a method to explore this EOS. Four qualitatively different model EOSs are tested against observations of SXTs. They imply different levels of the enhancement of neutrino emission in massive neutron stars by (1) the direct Urca process in nucleon/hyperon matter; (2) pion condensates; (3) kaon condensates; (4) Cooper pairing of neutrons in nucleon matter with the forbidden direct Urca process. A low level of the thermal quiescent emission of two SXTs, SAX J1808.4-3658 and Cen X-4, contradicts model (4). Observations of SXTs test the same physics of dense matter as observations of thermal radiation from cooling isolated neutron stars, but the data on SXTs are currently more conclusive.PACS. 97.60.Jd Neutron stars -26.60.+c Nuclear matter aspects of neutron stars

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“…This mechanism can enhance the neutrino luminosity of the star by a factor of < ∼ 30 − 100 over the modified Urca level [28,29].…”

Section: Neutrino Emission Mechanismsmentioning

confidence: 99%