scholarly journals Superfluid Phonons in Neutron Star Core

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 16
Author(s):  
Marcello Baldo
Keyword(s):  
Neutron Star ◽  
Inner Core ◽  
Mutual Influence ◽  
Collective Excitation ◽  
Neutron Matter ◽  
Superfluid Phase ◽  
S Wave ◽  
Spectral Functions ◽  
Open Problems ◽  
Linear Spectrum

In neutron stars the nuclear asymmetric matter is expected to undergo phase transitions to a superfluid state. According to simple estimates, neutron matter in the inner crust and just below should be in the s-wave superfluid phase, corresponding to the neutron-neutron 1S0 channel. At higher density in the core also the proton component should be superfluid, while in the inner core the neutron matter can be in the 3P2 superfluid phase. Superluidity is believed to be at the basis of the glitches phenomenon and to play a decisive influence on many processes like transport, neutrino emission and cooling, and so on. One of the peculiarity of the superfluid phase is the presence of characteristic collective excitation, the so called ’phonons’, that correspond to smooth modulations of the order parameter and display a linear spectrum at low enough momentum. This paper is a brief review of the different phonons that can appear in Neutron Star superfuid matter and their role in several dynamical processes. Particular emphasis is put on the spectral functions of the different components, that is neutron, protons and electrons, which reveal their mutual influence. The open problems are discussed and indications on the work that remain to be done are given.

scholarly journals Incommensurate Crystallization of Neutron Matter in Neutron Stars

2020 ◽  
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Specific Heat ◽  
Inner Core ◽  
Surface Region ◽  
Outer Core ◽  
Neutron Matter ◽  
High Mass ◽  
The Core ◽  
Gravitational Stress

The composition of the neutron stars from its surface region, outer-core, inner-core, and to its center is still being investigated. One can only surmise on the properties of neutron stars from the spectroscopic data that may be available from time to time. A few models have suggested that the matter at the surface region of the neutron star is composed of atomic nuclei that get crushed under extremely large pressure and gravitational stress, and this leads to the creation of solid lattice with a sea of electrons, and perhaps some protons, flowing through the gaps between them. Nuclei with high mass numbers, such as ferrous, gold, platinum, uranium, may exist in the surface region or in the outer-core region. It is found that the structure of the neutron star changes very much as one goes from the surface to the core of the neutron star. The surface region is extremely hard and very smooth. Surface irregularities are hardly of the order of 5 mm, whereas the interior of the neutron star may be superfluid and composed of neutron-degenerate matter. However, the neutron star is highly compact crystalline systems, and in terrestrial materials under pressure, many examples of incommensurate phase transitions have been discovered. Consequently, the properties of incommensurate crystalline neutron star have been studied. The composition of the neutron stars in the super dense state remains uncertain in the core of the neutron star. One model describes the core as superfluid neutron-degenerate matter, mostly, composed of neutrons , and a small percentage of protons and electrons More exotic forms of matter are possible, including degenerate strange matter. It could also be incommensurate crystalline neutron matter that could be BCC or HCP. Using principles of quantum statistical mechanics, the specific heat and entropy of the incommensurate crystalline neutron star has been calculated assuming that the temperature of the star may vary between to . Two values for the temperature T that have been arbitrarily chosen for which the calculations have been done are and . The values of specific heat and entropy decrease as the temperature increases, and also, their magnitudes are very small. This is in line with the second law of thermodynamics.

Ferromagnetism in neutron matter and its implication for the neutron star equation of state

2011 ◽  
Author(s):  
J. P. W. Diener ◽  
F. G. Scholtz ◽  
Ersin Göğüş ◽  
Ünal Ertan ◽  
Tomaso Belloni
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Matter

scholarly journals Nuclear Level Density Parameters ofPb203-209andBi206-210Deformed Target Isotopes Used on Accelerator-Driven Systems in Collective Excitation Modes

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Şeref Okuducu ◽  
Nisa N. Aktı ◽  
Sabahattin Akbaş ◽  
M. Orhan Kansu
Keyword(s):  
Collective Excitation ◽  
Level Density ◽  
Neutron Resonance ◽  
Nuclear Level Density ◽  
S Wave ◽  
Nuclear Level ◽  
Driven Systems ◽  
Resonance Data ◽  
Accelerator Driven Systems ◽  
Good Agreement

The nuclear level density parameters of some deformed isotopes of target nuclei (Pb, Bi) used on the accelerator-driven subcritical systems (ADSs) have been calculated taking into consideration different collective excitation modes of observed nuclear spectra near the neutron binding energy. The method used in the present work assumes equidistant spacing of the collective coupled state bands of the considered isotopes. The present calculated results for different collective excitation bands have been compared with the compiled values from the literature for s-wave neutron resonance data, and good agreement was found.

scholarly journals Spin rotation, Chandler wobble and free core nutation of isolated multi-layer pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 392-392
Author(s):  
Alexander Gusev ◽  
Irina Kitiashvili
Keyword(s):  
Neutron Star ◽  
Differential Rotation ◽  
Heat Dissipation ◽  
Inner Core ◽  
Outer Core ◽  
Chandler Wobble ◽  
Time Of Arrival ◽  
Layer Model ◽  
Free Core Nutation ◽  
Rotation Pole

AbstractAt present time there are investigations of precession and nutation for very different celestial multi-layer bodies: the Earth (Getino 1995), Moon (Gusev 2010), planets of Solar system (Gusev 2010) and pulsars (Link et al. 2007). The long-periodic precession phenomenon was detected for few pulsars: PSR B1828-11, PSR B1557-50, PSR 2217+47, PSR 0531+21, PSR B0833-45, and PSR B1642-03. Stairs, Lyne & Shemar (2000) have found that the arrival-time residuals from PSR B1828-11 vary periodically with a different periods. According to our model, the neutron star has the rigid crust (RC), the fluid outer core (FOC) and the solid inner core (SIC). The model explains generation of four modes in the rotation of the pulsar: two modes of Chandler wobble (CW, ICW) and two modes connecting with free core nutation (FCN, FICN) (Gusev & Kitiashvili 2008). We are propose the explanation for all harmonics of Time of Arrival (TOA) pulses variations as precession of a neutron star owing to differential rotation of RC, FOC and crystal SIC of the pulsar PSR B1828-11: 250, 500, 1000 days. We used canonical method for interpretation TOA variations by Chandler Wobble (CW) and Free Core Nutation (FCN) of pulsar.The two - layer model can explain occurrence twin additional fashions in rotation pole motion of a NS: CW and FCN. In the frame of the three-layer model we investigate the free rotation of dynamically-symmetrical PSR by Hamilton methods. Correctly extending theory of SIC-FOC-RC differential rotation for neutron star, we investigated dependence CW, ICW, FCN and FICN periods from flatness of different layers of pulsar.Our investigation showed that interaction between rigid crust, RIC and LOC can be characterized by four modes of periodic variations of rotation pole: CW, retrograde Free Core Nutation (FCN), prograde Free Inner Core Nutation (FICN) and Inner Core Wobble (ICW). In the frame of the three-layer model we proposed the explanation for all pulse fluctuations by differential rotation crust, outer core and inner core of the neutron star and received estimations of dynamical flattening of the pulsar inner and outer cores, including the heat dissipation. We have offered the realistic model of the dynamical pulsar structure and two explanations of the feature of flattened of the crust, the outer core and the inner core of the pulsar.

scholarly journals Spectral asymptotics for canonical systems

2018 ◽  
Vol 2018 (736) ◽  
pp. 285-315 ◽  
Author(s):  
Jonathan Eckhardt ◽  
Aleksey Kostenko ◽  
Gerald Teschl
Keyword(s):  
High Energy ◽  
Spectral Asymptotics ◽  
Spectral Functions ◽  
Open Problems ◽  
New Approach ◽  
Canonical Systems ◽  
First Order ◽  
Continuity Properties ◽  
High Energy Behavior ◽  
Energy Behavior

AbstractBased on continuity properties of the de Branges correspondence, we develop a new approach to study the high-energy behavior of Weyl–Titchmarsh and spectral functions of{2\times 2}first order canonical systems. Our results improve several classical results and solve open problems posed by previous authors. Furthermore, they are applied to radial Dirac and radial Schrödinger operators as well as to Krein strings and generalized indefinite strings.

scholarly journals The equation of state of neutron matter, symmetry energy and neutron star structure

2014 ◽  
Vol 50 (2) ◽  
Author(s):  
S. Gandolfi ◽  
J. Carlson ◽  
S. Reddy ◽  
A. W. Steiner ◽  
R. B. Wiringa
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Symmetry Energy ◽  
Neutron Matter ◽  
Star Structure

scholarly journals A CBF calculation of 1S0 Superfluidity in the Inner Crust of Neutron Stars

2019 ◽  
Vol 17 ◽  
pp. 23
Author(s):  
G. Pavlou ◽  
E. Mavrommatis ◽  
Ch. C. Moustakidis ◽  
J. W. Clark
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Basis Function ◽  
Correlation Functions ◽  
Short Range ◽  
Higher Order ◽  
Neutron Matter ◽  
S Wave ◽  
Short Range Correlations

Singlet S-wave superfluidity of dilute neutron matter in the inner crust of neutron stars is studied within the correlated BCS (Bardeen, Cooper, Schrieffer) method, taking into account both pairing and short-range correlations. First, the equation of state (EOS) of normal neutron matter is calculated within the correlated-basis-function (CBF) method in lowest cluster order using the Argonne V18 and V4′ potentials and Jastrow-type correlation functions. The 1S0 superfluid gap is then calculated with these potentials and correlation functions. The dependence of our results on the choice of the correlation functions is ana- lyzed and the role of higher-order cluster corrections is considered. The values obtained for the 1S0 gap within this simplified scheme are comparable to those from other, more elaborate, methods.

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