H2020Индивидуална стипендия2016–2018

Super-DENSE · Superfluid dynamics of neutron star crusts and cores

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2016-08-01 → 2018-07-31
Финансиране от ЕС: 146 462 €
Участници: 1
Схема: MSCA-IF-EF-RI

Линиите свързват координатора с партньорите.

Накратко на български

Невтронните звезди и поведението на свръхтечностите в тях се изследват чрез примери като внезапното ускоряване на радиопулсарите. Това помага за създаването на модели, които свързват квантовата физика на атомите с мащабите на цели звезди и гравитационните вълни.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Superfluid dynamics of neutron star crusts and cores

Neutron stars condense a mass comparable to that of the sun in a ten kilometre radius. As a consequence their interiors reach densities well above nuclear saturation density and allow to probe fundamental physics in regimes inaccessible to terrestrial experiments. Furthermore neutron stars are cold objects as, despite internal temperatures of tens of millions of degrees Kelvin, their thermal energy is negligible compared to their Fermi energy. This means that thermal excitations are too small to ‘free’ particles and allow them to interact. As a consequence, in the interior of a neutron star neutrons are superfluid and protons superconducting. Superfluidity has strong consequences on the dynamics of the star, as the superfluid can ‘flow’ relative to the `normal’ component of the star. A large scale, astrophysical, manifestation of superfluidity in neutron stars are pulsar glitches, sudden spin-ups observed in radio pulsars. Superfluidity, however, also has a strong impact on modes of oscillation of the neutron star. This is particularly interesting, as these modes can be probed with gravitational wave observations and allow to investigate the interior of the star, in much the same way as is done for our sun. These signals are, however, weak, and careful theoretical modelling is required to detect them and interpret them. This is a challenge, as one needs to understand how to extend quantum mechanical models of superfluid neutrons in the interior, on the scale of an atom, to the large scale dynamics of a 10 km star. The aim of this project is to develop methods to bridge the gap in scales between microscopic modelling of neutron superfluids and large scale hydrodynamics models of pulsar glitches and gravitational wave emission. The models that have been developed allow to use astrophysical observations to obtain constrains on microphysical parameters and thus constrain the behaviour of matter at high densities. The project contributes not only to our understanding of fundamental physics and the success of the LIGO/Virgo experiment, but also increases collaboration between different fields of Physics and between European institutions.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

Neutron stars are one of the most exciting nuclear physics laboratories in the Universe. With interior densities well above nuclear saturation density they allow us to probe conditions impossible to replicate on Earth. In addition the thermal energy of the star is negligible compared to the Fermi energy, and neutrons in the interior will be superfluid.Superfluidity affects the dynamics of the star, as now neutrons can flow relative to the ‘normal’ components of the star with little viscosity. A direct probe of such an effect is thought to come from pulsar ‘glitches’, sudden jumps in frequency observed in otherwise spinning down radio pulsars. Most theories of glitches are based on the idea that a large scale superfluid component of the star is decoupled from the spin-down of the ‘normal’ component, and its sudden re-coupling leads to a glitch.On theoretical grounds we expect this effect as a superfluid rotates by forming an array of quantised vortices, and these vortices are strongly attracted, or ‘pinned’, by ions in the neutron star crust (or superconducting flux tubes in the core). If the superfluid cannot expel ‘pinned’ vortices it cannot spin-down and builds up a lag with respect to the normal component, until hydrodynamical lift forces become strong enough to break the pinning.Despite the success of this picture in interpreting glitches, only recently has progress been made in quantitatively describing glitches with large scale hydrodynamical simulations, and statistics throughout the pulsar population with small scale quantum-mechanical simulations of vortex motion.This proposal aims to bridge the gap between these two scales by using inputs from quantum mechanical simulations to describe vortex unpinning in hydrodynamical simulations, which will include state of the art crustal physics and thermal conduction. We will thus quantitatively describe the response of the star to different kinds of glitches and obtain, for the first time, robust statistics.

Оригинален текст от CORDIS (на английски).

Участници

CENTRUM ASTRONOMICZNE IM. MIKOLAJA KOPERNIKA POLSKIEJ AKADEMII NAUK · WarszawaКоординаторПолша