36377156
BRIGHT "MERGER-NOVA" FROM THE REMNANT OF A NEUTRON STAR BINARY MERGER: A SIGNATURE OF A NEWLY BORN, MASSIVE, MILLISECOND MAGNETAR
A massive millisecond magnetar may survive the merger of a neutron star (NS) binary, which would continuously power the merger ejecta. We develop a generic dynamic model for the merger ejecta with energy injection from the central magnetar. The ejecta emission (the “merger-nova”) powered by the magnetar peaks in the UV band and the peak of the light curve progressively shifts to an earlier epoch with increasing frequency. A magnetar-powered mergernova could have an optical peak brightness comparable to a supernova, which is a few tens or hundreds times brighter than the radioactive-powered merger-novae (the so-called macro-nova or kilo-nova). On the other hand, such a merger-nova would peak earlier and have a significantly shorter duration than that of a supernova. An early collapse of the magnetar could suppress the brightness of the optical emission and shorten its duration. Such millisecond-magnetar-powered merger-novae may be detected from NS-NS merger events without an observed short gamma-ray burst, and could be a bright electromagnetic counterpart for gravitational wave bursts due to NS-NS mergers. If detected, it suggests that the merger leaves behind a massive NS, which has important implications for the equation-of-state of nuclear matter. Subject headings: gamma-ray burst: general — supernovae: general — stars: neutron
120879129
Effect of a strong magnetic field on the surface electric field of strange stars
We made a detailed study of the properties of the electron layer near the quark surface of strange stars with strong (${\sim}10^{14}{-}10^{17}$ G) magnetic fields. The electrostatic potential and the electric field at the quark surface were calculated as functions of the magnetic field intensity of bare strange stars. Using an ultrastrong ($B\geq 2.5\times10^{16}$ G) magnetic field, we found that the distribution of electrons becomes an exponential function of radial distance, which is quite different in a magnetic field-free case. We also calculated the variation in gap width between the strange core and the normal nuclear crust for strange stars, which is due to magnetic field effect.
121120033
Yields and isomeric ratio of xenon and krypton isotopes from thermal neutron fission of /sup 235/U
The experimental cumulative yields of /sup 85/Kr/sup m/, /sup 87/Kr, /sup 88/Kr, /sup 133/Xe/sup g/, /sup 135/Xe/sup m/, and /sup 135/Xe/sup g/ and the independent isomeric yield of /sup 133/Xe/sup m/ in the thermal neutron fission of /sup 235/U have been measured by the gas chromatographic method. The independent yields of /sup 133/Xe/sup g/, /sup 135/Xe/sup m/, and /sup 135/Xe/sup g/ were deduced with the aid of /sup 133/I and /sup 135/I data. The isomeric yield ratios of /sup 133/Xe and /sup 135/Xe have been computed and compared with theoretical values since they have the same high spin state J = 11/2/sup -/ and low spin ground state J = 3/2/sup +/. The influence of the shell effect on the fission isomeric yield ratio is discussed. From the measured independent yield of Xe isotopes plus the reported data, the Xe-isotopic distribution curve has been constructed. The curve is compared with the isotopic distribution curves of Xe isotopes formed in 11.5 GeV proton interactions with /sup 238/U and Cs isotopes formed in 24 GeV proton interactions with /sup 238/U. Upon fitting the yield curves we find that only those products with N/Z> or =1.48 fit a curve typical of a binarymore » fission process.« less
197531984
Thermal evolution of rotating strange stars in color superconductivity phase
119705192
Preliminary study of the K N interaction in a chiral constituent quark model
A preliminary investigation of $\overline{K}N$ interaction is performed within a chiral constituent quark model by solving the resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the $S$-, $P$-, $D$-, $F$-wave $\mathit{KN}$ scattering phase shifts. The channel-coupling between $\overline{K}N,\ensuremath{\pi}\ensuremath{\Lambda}$ and $\ensuremath{\pi}\ensuremath{\Sigma}$ is considered, and the scattering phase shifts as well as the bound-state problem of $\overline{K}N$ are dynamically studied. The results show that the $S$-wave $\overline{K}N$ interaction in the isospin $I=0$ channel is attractive, and in the extended chiral SU(3) quark model such an attraction can make for a $\overline{K}N$ bound state, which appears as a $\ensuremath{\pi}\ensuremath{\Sigma}$ resonance in the coupled-channel calculation, while the chiral SU(3) quark model cannot accommodate the existence of a $\overline{K}N$ bound state. It seems that the vector meson exchanges are necessary to be introduced in the quark-quark interactions if one tries to explain the $\ensuremath{\Lambda}(1405)$ as a $\overline{K}N$ bound state or a $\ensuremath{\pi}\ensuremath{\Sigma}$-$\overline{K}N$ resonance state.
119022638
A statistical classification of the unassociated gamma-ray sources in the second Fermi Large Area Telescope Catalog
With the assistance of the identified/associated sources in the second Fermi Large Area Telescope (LAT) catalog, we analyze and resolve the spatial distribution and the distributions of the gamma-ray spectral and variability indices of the remaining 575 unassociated Fermi LAT sources. Consequently, it is suggested that the unassociated sources could statistically consist of Galactic supernova remnants/pulsar wind nebulae, BL Lacertae objects, flat spectrum radio quasars and other types of active galaxies with fractions of 25%, 29%, 41% and 5%, respectively.
119329935
THE SHORT RANGE MECHANISM OF N-N INTERACTION IN THE EXTENDED CHIRAL SU(3) QUARK MODEL
We give the comparisons between the chiral SU(3) quark model and the extended chiral SU(3) quark model. The results show that the phase shifts of NN scattering are very similar. However, the short range mechanisms of nucleon-nucleon interaction are totally different. In the chiral SU(3) quark model, the short range interaction is dominantly from OGE, and in the extended chiral SU(3) quark model, it is dominantly from vector meson exchanges.
115699498
A study of nucleon-nucleon spin-orbit force in quark model
Abstract Spin-orbit interactions between two quarks due to the one-gluon exchange, confinement potential, σ-exchange of the chiral field and two-gluon exchange are considered in our calculation. As a consequence, the spin-orbit energy splitting of the 1P state in the baryon spectrum and the 3 P 2 phase shifts of NN scattering can unifiedly be explained.
120567337
A study of nucleon-nucleon interaction from the quark-antiquark pair creation model
The NN interaction is studied with the quark cluster model by including the equivalent one-meson-exchange potentials and two-pion-exchange potential, which are constructed from the quark-antiquark pair-creation transition potential. The results show that the long-range part of the equivalent meson-exchange potential is similar to that of the conventional meson-exchange potential, and the medium-range part of the equivalent meson-exchange potential is attractive, but the strength of the latter is not enough to explain the phase shifts of S-wave NN scattering.
120930803
SPIN-ORBIT FORCE OF HYPERON-NUCLEON INTERACTION IN THE CHIRAL SU(3) QUARK MODEL
The spin-orbit (LS) force of the hyperon-nucleon interaction is studied in the chiral SU(3) quark model. The symmetric LS terms from the one gluon exchange (OGE) and the scalar nonet exchange (OSE) are taken into account. It is shown that two different treatments (the LS coupling from either OGE or OSE being artificially enhanced in order to reproduce the P-3(J) phase shifts of the nucleon-nucleon scattering) lead to very similar LS couplings in the Sigma N(I = 3/2) channel but give quite different results in the Lambda N - Sigma N(I = 1/2) coupled-channel system. A prominent resonance occurs in the P-1(1) state of the Lambda N channel mainly due to the stronger LS(-) couplings in the Lambda N - Sigma N(I = 1/2) coupled-channel system in the OGE enhanced case. Comparatively the Lambda N P-1(1) phase shift curve exhibits a rather smooth behaviour in the OSE enhanced case. Comparing our theoretical results with the experimental data available, and considering the requirement of the baryon spectrum, one can deduce that a stronger color-independent LS coupling is preferred in the chiral quark model. (C) 1998 Elsevier Science B.V.
125842933
Omega omega states in a chiral quark model
The structures of Omega omega states with spin-parity J(P) = 5/2(-), 3/2(-), and 1/2(-) are dynamically studied in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the energies of the baryon ground states, the binding energy of the deuteron, the nucleon-nucleon (NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The calculated results show that the Omega omega state has an attractive interaction, and in the extended chiral SU(3) quark model such attraction can make for a Omega omega quasi-bound state with spin-parity JP = 3/2- or 5/2- and the binding energy of about several MeV.