Compact stars within a soft symmetry energy quark-meson-coupling model

Panda, P. K.; Santos, A. M.; Menezes, D. P.; Providência, Constança

doi:10.1103/physrevc.85.055802

Cited by 32 publications

(49 citation statements)

References 61 publications

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“…As already discussed in [7,22], a smaller slope L im- plies a softer increase of the strangeness fraction with density. However, because the central density of these stars is larger, it is important to study the total hyperon content of the star.…”

Section: Formalismmentioning

confidence: 62%

“…It was also shown that a softer symmetry energy corresponds to a slower increase of the hyperon fraction with density [7,22]. However, the onset of strangeness depends on the charge of the hyperons.…”

Section: Discussionmentioning

confidence: 99%

“…In order to test the effect of the symmetry energy slope we will introduce a non-linear ω − ρ term as in [21] and change the coupling so that models with equivalent isoscalar properties of TM1 but different density dependence of the symmetry energy will be obtained. As discussed in [7,[21][22][23] this term reflects itself on the star properties, namely giving rise to a smaller radii. We will show that this effect is larger for nucleonic stars than for hyperonic stars and that, in fact, the presence of hyperons gives rise to a similar effect that masks the symmetry energy one.…”

Section: Introductionmentioning

confidence: 99%

“…The measurement of the mass of the mili-second pulsar PSR J1614-2230 with high precision, M = 1.97±0.04 M ⊙ [1], has given origin to a large number of studies that discuss whether there is room for hyperons or other exotic degrees of freedom inside this star [2][3][4][5][6][7]. In particular microscopic calculations using the non-relativistic Brueckner-Hartree-Fock formalism predict a very large softening of the equation of state (EOS) when hyperons are taken into account, and are not even able to account for the standard neutron star masses of the order ∼ 1.4 M ⊙ [8].…”

Section: Introductionmentioning

confidence: 99%

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Interplay between the symmetry energy and the strangeness content of neutron stars

Providência

Rabhi

2013

Phys. Rev. C

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The effect of the density dependence of the nucleonic equation of state and the hyperon meson couplings on the star properties, including strangeness content, mass and radius, are studied within a relativistic mean field formalism. It is shown that there is still lacking information on the nucleonic equation of state at supra-saturation densities and on the hyperon interactions in nuclear matter that will allow a clear answer to the question whether the mass of the pulsar J1614-2230 could rule out exotic degrees of freedom from the interior of compact stars. We show that some star properties are affected in a similar way by the density dependence of the symmetry energy and the hyperon content of the star. To disentangle these two effects it is essential to have a good knowledge of the equation of state at supra-saturation densities. A linear correlation between the radius and the strangeness content of a star with a fixed mass is obtained.

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Section: Formalismmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interplay between the symmetry energy and the strangeness content of neutron stars

Providência

Rabhi

2013

Phys. Rev. C

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“…It is shown that there is still lacking information on the nucleonic equation of state at supra-saturation densities and, in particular, on the hyperon interactions in nuclear matter. Therefore, the role of exotic degrees of freedom on the interior of compact stars is still an open issue [13,14,15,16].…”

Section: Introductionmentioning

confidence: 99%

Imprint of the symmetry energy on the inner crust and strangeness content of neutron stars

et al. 2014

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Abstract. In this work we study the effect of the symmetry energy on several properties of neutron stars. First, we discuss its effect on the density, proton fraction and pressure of the neutron star crust-core transition. We show that whereas the first two quantities present a clear correlation with the slope parameter L of the symmetry energy, no satisfactory correlation is seen between the transition pressure and L. However, a linear combination of the slope and curvature parameters at ρ = 0.1 fm −3 is well correlated with the transition pressure.In the second part we analyze the effect of the symmetry energy on the pasta phase. It is shown that the size of the pasta clusters, number of nucleons and the cluster proton fraction depend on the density dependence of the symmetry energy: a small L gives rise to larger clusters. The influence of the equation of state at subsaturation densities on the extension of the inner crust of the neutron star is also discussed. Finally, the effect of the effect of the density dependence of the symmetry energy on the strangeness content of neutron stars is studied in the last part of the work. It is found that charged (neutral) hyperons appear at smaller (larger) densities for smaller values of the slope parameter L. A linear correlation between the radius and the strangeness content of a star with a fixed mass is also found.PACS. 26.60.-c Nuclear matter aspects of neutron stars -21.65.-f Nuclear matter

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Timing sequence changes of landscape plants in Shanghai Area, China

Yang

Tang

Shao

et al. 2011

J. Shanghai Jiaotong Univ. (Sci.)

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Based on published reports and direct observation, the common resources of landscape plant species in the Shanghai area were identified and studied in terms of the landscape characteristics of timing sequence changes over a one year time period. The results showed that there were 199 common landscape plant species in Shanghai, distributed in 67 families and 129 genera. These plants were categorized by three ornamental characteristics: flowers, foliage and fruits. The species were thus further analyzed according to the time periods which these characteristics were present. The results showed that flower ornamental distributed throughout the year, particularly from April to June, and plant species with colorful foliage could be seen every month, and particularly in November and December. On the other hand, few plant species with fruit ornamentals were observed in Shanghai area. The diversity of landscape timing sequence changes of the 199 plant species under examination was then analyzed by using the Shannon-Weiner and Simpson index formulas. The results showed that the higher diversity was observed in January, February and from August to October, while the lowest diversity was recorded from March to July and during November and December. The diversity of landscape characteristics of these plants was ranked according to foliage, flowers and fruit. Using this method, one park and one plant community were selected to evaluate the advantages and disadvantages of their time-changing plant landscape, with the goal of assessing the validity of the chosen ranking method. These results in the present study would be helpful to evaluate the plant landscape in a specified space and further enrich the diversity of plant and landscape by a target-oriented way.Modern urban landscaping brings ecological and social benefits to city residents, including direct contact with seasonal scenery changes. Landscape plants are the main elements for these timing sequence changes, and their annual life rhythms provide the basis for developing harmonious landscaping [1] . Indeed, timing sequence changes of landscape plants is the key factor for enriching garden diversity, as emphasis on diverse seasonal changes of landscape plants is an important way to improve the quality of urban green spaces. Up to now, there were many reports on the importance and evaluation about the seasonal changes of plants around the world [2][3] .In the past two decades, landscaping has made significant achievements in improving the public parks in Shanghai. Specifically, considerable effort has been made to increase the seasonal changes and introduce the diverse colorful plant species in green space. For example, through selecting and domesticating a variety of colorful plant and shrub species not indigenous to the Shanghai area, the diversity of foliage ornamentals has increased [4][5] . However, this process requires long-term research and practice so as to achieve a properly multifaceted enriching diversity of landscape plants in Shanghai. It is therefore import...

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Compact stars within a soft symmetry energy quark-meson-coupling model

Cited by 32 publications

References 61 publications

Interplay between the symmetry energy and the strangeness content of neutron stars

Interplay between the symmetry energy and the strangeness content of neutron stars

Imprint of the symmetry energy on the inner crust and strangeness content of neutron stars

Timing sequence changes of landscape plants in Shanghai Area, China

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