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Strange matter and its stability in presence of magnetic field  [PDF]
Pradip K Sahu
Physics , 1995,
Abstract: We study the effect of a magnetic field on the interacting quark matter and apply to strange star. We considere the low temperature approximation to strange matter. We find that the interacting strange quark matter is more stable compare to free quark gas in presence of strong external magnetic field with zero and finite temperature. We then calculate strange star structure parameters such as mass and radius and find that the strange star is more compact for interacting quark matter than free quark matter in presence of strong magnetic field.
Calculation of the Structure Properties of a Strange Quark Star in the Presence of Strong Magnetic Field Using a Density Dependent Bag Constant  [PDF]
Gholam Hossein Bordbar,Hajar Bahri,Fatemeh Kayanikhoo
Physics , 2012, DOI: 10.1088/1674-4527/12/9/008
Abstract: In this article we have calculated the structure properties of a strange quark star in static model in the presence of a strong magnetic field using MIT bag model with a density dependent bag constant. To parameterize the density dependence of bag constant, we have used our results for the lowest order constrained variational calculation of the asymmetric nuclear matter. By calculating the equation of state of strange quark matter, we have shown that the pressure of this system increases by increasing both density and magnetic field. Finally, we have investigated the effect of density dependence of bag constant on the structure properties of strange quark star.
Structure of Spin Polarized Strange Quark Star in the Presence of Magnetic Field at Finite Temperature
Bordbar, G. H.;Kayanikhoo, F.;Bahri, H.
High Energy Physics - Phenomenology , 2013,
Abstract: In this paper, we have calculated the thermodynamic properties of spin polarized strange quark matter at finite temperature in the presence of a strong magnetic field using MIT bag model. We have also computed the equation of state of spin polarized strange quark matter in the presence of strong magnetic field and finally, using this equation of states we have investigated the structure of spin polarized strange quark star at different temperatures and magnetic fields.
Structure of Spin Polarized Strange Quark Star in the Presence of Magnetic Field at Finite Temperature  [PDF]
G. H. Bordbar,F. Kayanikhoo,H. Bahri
Physics , 2013,
Abstract: In this paper, we have calculated the thermodynamic properties of spin polarized strange quark matter at finite temperature in the presence of a strong magnetic field using MIT bag model. We have also computed the equation of state of spin polarized strange quark matter in the presence of strong magnetic field and finally, using this equation of states we have investigated the structure of spin polarized strange quark star at different temperatures and magnetic fields.
Hot Spin Polarized Strange Quark Stars in the Presence of Magnetic Field using a density dependent bag constant  [PDF]
G. H. Bordbar,Z. Alizade
Physics , 2013, DOI: 10.1007/s10511-014-9320-2
Abstract: The effect of magnetic field on the structure properties of hot spin polarized strange quark stars has been investigated. For this purpose, we use the MIT bag model with a density dependent bag constant to calculate the thermodynamic properties of spin polarized strange quark matter such as energy and equation of state. We see that the energy and equation of state of strange quark matter changes significantly in a strong magnetic field. Finally, using our equation of state, we compute the structure of spin polarized strange quark star at different temperatures and magnetic fields.
Rotation And Magnetic Evolution Of Superconducting Strange Stars  [PDF]
H. F. Chau
Physics , 1996, DOI: 10.1086/303898
Abstract: Is pulsar make up of strange matter? The magnetic field decay of a pulsar may be able to give us an answer. Since Cooper pairing of quarks occurs inside a sufficiently cold strange star, the strange stellar core is superconducting. In order to compensate the effect of rotation, different superconducting species inside a rotating strange star try to set up different values of London fields. Thus, we have a frustrated system. Using Ginzburg-Landau formalism, I solved the problem of rotating a superconducting strange star: Instead of setting up a global London field, vortex bundles carrying localized magnetic fields are formed. Moreover, the number density of vortex bundles is directly proportional to the angular speed of the star. Since it is energetically favorable for the vortex bundles to pin to magnetic flux tubes, the rotational dynamics and magnetic evolution of a strange star are coupled together, leading to the magnetic flux expulsion as the star slows down. I investigate this effect numerically and find that the characteristic field decay time is much less than 20~Myr in all reasonable parameter region. On the other hand, the characteristic magnetic field decay time for pulsars is $\geq 20$~Myr. Thus, my finding cast doubt on the hypothesis that pulsars are strange stars.
The Galactic Magnetic Field's Effect in Star-Forming Region  [PDF]
Ian W. Stephens,Leslie W. Looney,C. Darren Dowell,John E. Vaillancourt,Konstantinos Tassis
Physics , 2010, DOI: 10.1088/0004-637X/728/2/99
Abstract: We investigate the effect of the Milky Way's magnetic field in star forming regions using archived 350 micron polarization data on 52 Galactic star formation regions from the Hertz polarimeter module. The polarization angles and percentages for individual telescope beams were combined in order to produce a large-scale average for each source and for complexes of sources. In more than 80% of the sources, we find a meaningful mean magnetic field direction, implying the existence of an ordered magnetic field component at the scale of these sources. The average polarization angles were analyzed with respect to the Galactic coordinates in order to test for correlations between polarization percentage, polarization angle, intensity, and Galactic location. No correlation was found, which suggests that the magnetic field in dense molecular clouds is decoupled from the large-scale Galactic magnetic field. Finally, we show that the magnetic field directions in the complexes are consistent with a random distribution on the sky.
The effect of the neutron star crust on the evolution of a core magnetic field  [PDF]
D. Konenkov,U. Geppert
Physics , 1999, DOI: 10.1046/j.1365-8711.2000.03188.x
Abstract: We consider the expulsion of the magnetic field from the super-conducting core of a neutron star and its subsequent decay in the crust. Particular attention is paid to a strong feedback of the distortion of magnetic field lines in the crust on the expulsion of the flux from the core. This causes a considerable delay of the core flux expulsion if the initial field strength is larger than 10^{11} G. It is shown that the hypothesis on the magnetic field expulsion induced by the neutron star spin-down is adequate only for a relatively weak initial magnetic field $B \approx 10^{11}$ G. The expulsion time-scale depends not only on the conductivity of the crust, but also on the initial magnetic field strength itself. Our model of the field evolution naturally explains the existence of the residual magnetic field of neutron stars. Its strength is correlated with the impurity concentration in neutron star crusts and anti-correlated with the initial field strengths.
Timing evolution of accreting strange stars  [PDF]
D. Blaschke,I. Bombaci,H. Grigorian,G. Poghosyan
Physics , 2001, DOI: 10.1016/S1384-1076(02)00087-8
Abstract: It has been suggested that the QPO phenomenon in LMXB's could be explained when the central compact object is a strange star. In this work we investigate within a standard model for disk accretion whether the observed clustering of spin frequencies in a narrow band is in accordance with this hypothesis. We show that frequency clustering occurs for accreting strange stars when typical values of the parameters of magnetic field initial strength and decay time, accretion rate are chosen. In contrast to hybrid star accretion no mass clustering effect is found.
Mixed phase in a compact star with strong magnetic field  [PDF]
Ritam Mallick,P. K. Sahu
Physics , 2012,
Abstract: Compact stars can have either hadronic matter or can have exotic states of matter like strange quark matter or color superconducting matter. Stars also can have a quark core surrounded by hadronic matter, known as hybrid stars (HS). The HS is likely to have a mixed phase in between the hadron and quark phase. Observational results suggest huge surface magnetic field in certain neutron stars (NS) called magnetars. Here we study the effect of strong magnetic field on the respective EOS of matter under extreme conditions. We further study the hadron-quark phase transition in the interiors of NS giving rise to hybrid stars (HS) in presence of strong magnetic field. The hadronic matter EOS is described based on relativistic mean field theory and we include the effect of strong magnetic fields leading to Landau quantization of the charged particles. For the quark phase we use the simple MIT bag model. We assume density dependent bag pressure and magnetic field. The magnetic field strength increases going from the surface to the center of the star. We construct the intermediate mixed phase using Glendenning conjecture. The magnetic field softens the EOS of both the matter phases. The effect of magnetic field is insignificant unless the field strength is above $10^{14}$G. A varying magnetic field, with surface field strength of $10^{14}$G and the central field strength of the order of $10^{17}$G has significant effect on both the stiffness and the mixed phase regime of the EOS. We finally study the mass-radius relationship for such type of mixed HS, calculating their maximum mass, and compare them with the recent observation of pulsar PSR J1614-2230, which is about 2 solar mass. The observations puts a severe constraint on the EOS of matter at extreme conditions. The maximum mass with our EOS can reach the limit set by the observation.
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