Annual NewCompStar Conference 2016

Session

Afternoon session

25 Apr 2016, 14:00

Bogazici University-Rectorate Building (Istanbul)

4. The Critical Strain Angle along the Neutron Star Crust

Mr Onur Akbal

25/04/2016, 14:00

We estimate the critical strain angle throughout the neutron star crust. We propose that the critical strain angle is proportional to the ratio of the total Coulomb potential energy to the kinetic energy of the relativistic electrons, $\theta_{cr} \sim E_{C}/E_{K}$, in one Wigner-Sietz cell. Since the character of the Coulomb interaction varies throughout the inner crust according to the...

5. The effect of the magnetic field on the inner crust of neutron stars

Mr Constança Provdência

25/04/2016, 14:20

The effect of strong magnetic fields, of the order of 10^{16}-10^{17}G, on the extension of the crust of magnetized neutron stars is discussed. The dynamical instability region of neutron-proton-electron matter at subsaturation densities and the mode with the largest growth rate are determined within a relativistic mean field model. It is shown that a strong magnetic field has a large effect...

6. Spin polarized neutron star matter and core-crust transition in the neutron stars

Dr Mohsen Bigdeli

25/04/2016, 14:40

It is well known that the magnetars and the pulsars are neutron stars have strong surface magnetic field about 1015 [2] and 1013 [3] Gauss, respectively. The structural properties of these objects, such as its maximum mass and the location of core-crusts interface, is a subject that theoretical astrophysicists have desired to study. In order to determine the core-crust transition parameters,...

8. Modification of magicity toward the dripline and its impact on electron-capture rates for stellar core collapse

Adriana Raduta (IFIN-HH)

25/04/2016, 15:00

The importance of microphysical inputs from laboratory nuclear experiments and theoretical nuclear structure calculations in the understanding of core collapse dynamics and the subsequent supernova explosion, is largely recognized in the recent literature. In this work, we analyze the impact of the masses of very neutron rich nuclei on the matter composition during collapse, and the...

9. Electromagnetic structure of Neutron Stars

Mr Antonio Graziano Pili

25/04/2016, 15:20

Physical and observational properties of neutron stars (NSs) are deeply influenced by the morphology of their magnetic field. Therefore an accurate description of both the interior and exterior stellar magnetic field is necessary to improve our understanding of NS phenomenology. I will present a comprehensive numerical study of GR equilibria of magnetised NSs, taking into account different...

15. A simple model for pulsar glitches

Mr Marco Antonelli

26/04/2016, 14:00

In my presentation I'll describe an analytical two-components model for pulsar rotational dynamics: the aim is to reduce the computationally difficult 3D hydrodynamics to a 1D (radial) problem. The model takes into account consistently for the non-uniform structure of the star and superfluid entrainment. I'll show how this simple model can be used to put a constraint to the mass of the pulsars...

48. Accretion in white dwarf binaries - short time variability and broadband noise characteristics: connecting CVs to neutron star and black hole binaries

Prof. Şolen Balman

26/04/2016, 14:20

I review accretion in Cataclysmic Variable systems with emphasis on flicker
noise and its variations that have been a diagnostic tool in understanding the structure in accretion disks.
I study the nature of time variability of brightness of non-magnetic
cataclysmic variables. Dwarf novae demonstrate band limited noise in the UV and X-ray energy bands, which can be adequately explained
in the...

17. Force-free magnetospheres of neutron stars

Dr Taner Akgün

26/04/2016, 14:40

Evolution of magnetic fields in neutron stars depends strongly on the specific boundary conditions imposed at the stellar surface and the properties of the surrounding magnetosphere. In this talk, I will present various current-free (vacuum) and force-free models of neutron star magnetospheres, describe the resulting boundary conditions, and discuss their implications for the evolution of the...

18. Non-ideal effects in relativistic plasmas with the ECHO code for GRMHD

Luca Del Zanna

26/04/2016, 15:00

Axisymmetric GRMHD equilibria in 3+1: general formalism, numerical methods, and application to magnetized NS modeling We review the force-free and GRMHD equations for stationary and axisymmetric equilibria in general relativity within the 3+1 formalism. Numerical methods and detailed GRMHD modeling for the description of the structure and magnetosphere of magnetized neutron stars are shown and...

19. Learning about neutron stars from pulsar precession observations

Mr Gregory Ashton

26/04/2016, 15:20

I present results studying the periodic variations in PSR B1828-11 and demonstrate that the evidence is in favour of a precession interpretation over the recent claims that this pulsar is undergoing magnetospheric switching. Furthermore, I will establish that the periodicity is changing and discuss the consequence that this has for both models.

20. 3D Hall Evolution of Magnetic Fields in Neutron Stars

Dr Justin Elfritz

26/04/2016, 15:40

We have recently developed a 3D numerical model to evolve the Hall-Ohmic magnetic field in neutron stars (NSs). Our model is an important extension to the state-of-the-art 2D magneto-thermal model of Pons+ (2007, 2009), Vigano+ (2012, 2013). We have now validated and benchmarked our new 3D model, and we are beginning to investigate how Hall-driven evolution in 3D compares to the known...

32. Spherically Symmetric Core-Collapse Supernova Simulations

Mr Kevin Ebinger

28/04/2016, 14:20

Core-Collapse Supernovae (CCSNe) occur at the end of the evolution of massive stars. The detailed explosion mechanism of these violent events and their outcomes are still not fully understood. On the one hand multi-dimensional simulations of CCSNe are needed to investigate the underlying explosion mechanism. On the other hand they are currently too expensive to allow broad systematic studies,...

33. R-process nucleosynthesis and binary neutron star mergers

Mr Luke Bovard

28/04/2016, 14:40

The question of the origin of heavy elements has undergone a change in the last few years. Recent numerical simulations have demonstrated that binary neutron star mergers are the most likely progenitors of heavy elements in our galaxy instead of core-collapse supernova. This is due to a more neutron-rich environment that allows a more robust rapid neutron capture (r-process) nucleosynthesis....

34. Hadron-quark phase transition in hybrid stars and first insights for generating a new supernova EoS

Mr Oliver Heinimann

28/04/2016, 15:00

The subject of this presentation is the quark-hadron phase transition in neutron stars (NS) and core collapse supernovae (CCSN). We employ a hybrid equation of state consisting of the the state-of-the-art EOS HS(DD2) for the hadronic part and the constant speed of sound EOS for the quark phase. We show how this EOS is related to a standard bag model. We systematically vary the phase transition...

35. Cool quark matter

Aleksi Vuorinen

28/04/2016, 15:20

I will report results from recent efforts in perturbative QCD to build a framework for dealing with the bulk thermodynamic properties of dense quark matter at small but nonzero temperatures. The new results extend the applicability of the current state-of-the-art Equation of State of zero-temperature quark matter, smoothly connecting it to that of hot quark-gluon plasma. Applications of the...

31. Neutrino-nucleon interactions in supernovae matter

Dr Andreas Lohs

28/04/2016, 15:40

Neutrino-nucleon interactions at high density and temperature play a major role in the outcome of various processes during core-collapse supernovae (CCSNe) explosions. Their impact ranges from shock revival via neutrino heating to determining nucleosynthesis of heavy elements in the neutrino driven wind or via neutrino nucleosynthesis. Precise modelling of these scenarios requires accurate...

52. Constraints on the neutron star properties from the relativistic energy density functional

Prof. Nils Paar

29/04/2016, 14:00

Recent developments of the relativistic nuclear energy density functional (RNEDF) provide a self-consistent framework for the description of a variety of nuclear properties of astrophysical relevance, including the nuclear matter equation of state, and various neutron star properties. The RNEDF is supplemented with the covariance analysis in order to assess statistical uncertainties of...

42. Numerical modelling of compact static stars in Minimal Dilatonic Gravity

Denitsa Staicova

29/04/2016, 14:20

The minimal dilatonic gravity (MDG) is a theory, which is locally equivalent to the f(R) theories of gravity and gives an alternative description of the effects of dark matter and dark energy. In this talk we report the progress on modelling relativistic static spherically symmetric stars in MDG under different equations of state (EOS) of neutron matter and we discuss the dependence of the...

53. Relativistic stars in Starobinsky gravity with matched asymptotic expansion

Mr Sercan Çıkıntoğlu

29/04/2016, 14:40

We study the structure of relativistic stars in R+alpha*R^2 theory using the method of matched asymptotic expansion to handle the higher order derivatives in field equations arising from the higher order curvature term. We find solutions, parametrized by $\alpha$, for uniform density stars matching to the Schwarzschild solution outside the star. We obtain the mass-radius relations and study...

54. Excluded volume effect and neutron stars’ equation of state

Prof. Ludwik Turko

29/04/2016, 15:00

After a short review on the role of excluded volume corrections for the equation of state (EoS) of hadronic matter as probed in heavy-ion collision experiments [1], we present recent applications of excluded volume modifications in the EoS of neutron stars including a Bayesian analysis of mass-radius constraints and hybrid star phenomenology [2] and neutron star cooling [3]. We argue that the...

16. Microscopic Vortex Velocity for Neutron Stars

Mr Erbil Gügercinoğlu

29/04/2016, 15:20

Rotational dynamics of a neutron star is governed by the distribution and motion of vortex lines within the neutron superfluid. Interaction of the vortex lines with the ambient matter plays a significant role in the glitches, thermal evolution and magnetic field evolution of pulsars. Thus, correctly treating the vortex motion in the inner crust and the outer core of neutron stars is a key...

44. Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

Marcio de Avellar (Universidade de São Paulo)

29/04/2016, 15:40

A step towards to understanding how radiative processes give rise to the rich set of variability features, namely the quasi-periodic oscillations, actually seen in the X-ray light curves of low-mass X-ray binaries is given by the study of the energy and frequency dependence of the phase lags of the QPOs in the light curves. Here we studied the phase lags of all QPOs in the range of 1 Hz to...