The X-ray plateau followed by a steep decay ("internal plateau") has been observed in both long and short gamma-ray burst (GRBs), implying a millisecond magnetar operating in some GRBs. The sharp decay at the end of plateau, marking the abrupt cessation of the magnetar central engine, has been considered as the collapse of a supra-massive magnetar to a black hole (BH) when it spins down. If "internal plateau" is indeed the evidence of a magnetar central engine, a natural expectation is a signature from the newborn BH in some candidates. In this work, we find that GRB 070110 is a particular case, which shows a small X-ray bump following its "internal plateau". We interpret the plateau with a spin-down supra-massive magnetar and the X-ray bump with a fall-back BH accretion. This indicates that the newborn BH is likely active in some GRBs. Therefore, GRB 070110-like events may provide a further support to the magnetar central engine model and enable us to investigate the properties of the magnetar as well as the newborn BH.

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The successful joint observation of the gravitational wave event GW170817 and its multi-wavelength electromagnetic counterparts first enables human to witness a definite merger event of two neutron stars (NSs). This historical event confirms the origin of short-duration gamma-ray bursts (GRBs), and in particular, identifies the theoretically-predicted kilonova phenomenon that is powered by radioactive decays of r-process heavy elements. However, whether a long-lived remnant NS could be formed during this merger event remains unknown, although such a central engine has been suggested by afterglow observations of some short-duration GRBs. By invoking this long-lived remnant NS, we here propose a model of hybrid energy sources for the kilonova AT2017gfo associated with GW 170817. While the early emission of AT2017gfo is still powered radioactively as usually suggested, its late emission is primarily caused by delayed energy injection from the remnant NS. In our model, only one single opacity is required and an intermediate value of κ ≃ 0.97 cm 2 g −1 is revealed, which could be naturally provided by lanthanide-rich ejecta that is deeply ionized by the emission from a wind of the NS. These self-consistent results indicate that a long-lived remnant NS, which must own a very stiff equation of state, had been formed during the merger event of GW170817. This provides a very stringent constraint on the strong interaction in nuclear-quark matter. It is further implied that such GW events could provide a probe of the early spin and magnetic evolutions of NSs, e.g., the burying of surface magnetic fields.

The chiral SU (3) quark model is extended to include coupling between vector chiral field and quarks. By using this model, the phase shifts of NN scattering for different partial waves are studied. The results are very similar to those of the chiral SU(3) quark model calculation, in which one gluon exchange (OGE) plays dominate role in the short range part of the quark-quark interactions. Only in the 1 S0 case, the one channel phase shifts of the extended chiral SU (3) quark model are obviously improved.Key words: NN interaction, Quark Model, Chiral Symmetry. IntroductionAs is well known, in the light quark system the non-perturbative Quantum Chromodynamics (QCD) effect is important and not negligible. An effective approach to describe such effect can be made by introducing the coupling between the chiral fields and quarks, especially in studying the nucleonnucleon (N-N) interactions. A chiral SU (3) quark model [1,2] was proposed by generalizing the idea of the SU (2) σ model to the flavor SU (3) case. In the original chiral SU (3) quark model, the nonet pseuo-scalar meson exchanges and the nonet scalar meson exchanges are considered in describing the medium and long range parts of the interactions, and the one gluon exchange (OGE) potential is still retained to contribute the short range repulsion. By using this model, the energies of the baryon ground states, the N-N scattering phase shifts and the hyperon-nucleon (Y-N) cross sections can be reproduced reasonably. It seems that the repulsive core of the N-N interaction can be explained by the OGE and the quark exchange effect.Since last few years, Shen et al [3], Riska and Glozman [4,5] applied the quark-chiral field coupling model to study the baryon structure. They found that the chiral field coupling is also important in explaining the structure of baryons. Especially, the π field coupling leads to increase the weight of D

The groundbreaking discovery of the optical transient AT2017gfo associated with GW170817 opens a unique opportunity to study the physics of double neutron star (NS) mergers. We argue that the standard interpretation of AT2017gfo as being powered by radioactive decays of r-process elements faces the challenge of simultaneously accounting for the peak luminosity and peak time of the event, as it is not easy to achieve the required high mass, and especially the low opacity of the ejecta required to fit the data. A plausible solution would be to invoke an additional energy source, which is probably provided by the merger product. We consider energy injection from two types of the merger products: (1) a post-merger black hole powered by fallback accretion; and (2) a long-lived NS remnant. The former case can only account for the early emission of AT2017gfo, with the late emission still powered by radioactive decay. In the latter case, both early-and late-emission components can be well interpreted as due to energy injection from a spinning-down NS, with the required mass and opacity of the ejecta components well consistent with known numerical simulation results. We suggest that there is a strong indication that the merger product of GW170817 is a long-lived (supramassive or even permanently stable), low magnetic field NS. The result provides a stringent constraint on the equations of state of NSs.

We show that the peculiar early optical and in particular X-ray afterglow emission of the short duration burst GRB 130603B can be explained by continuous energy injection into the blastwave from a supra-massive magnetar central engine. The observed energetics and temporal/spectral properties of the late infrared bump (i.e., the "kilonova") are also found consistent with emission from the ejecta launched during an NS-NS merger and powered by a magnetar central engine. The isotropicequivalent kinetic energies of both the GRB blastwave and the kilonova are about E k ∼ 10 51 erg, consistent with being powered by a near-isotropic magnetar wind. However, this relatively small value demands that most of the initial rotational energy of the magnetar (∼ a few × 10 52 erg) is carried away by gravitational wave radiation. Our results suggest that (i) the progenitor of GRB 130603B would be a NS-NS binary system, whose merger product would be a supra-massive neutron star that lasted for about ∼ 1000 seconds; (ii) the equation-of-state of nuclear matter would be stiff enough to allow survival of a long-lived supra-massive neutron star, so that it is promising to detect bright electromagnetic counterparts of gravitational wave triggers without short GRB associations in the upcoming Advanced LIGO/Virgo era.

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We discuss the structure of Deltaron dibaryon in the chiral SU (3) quark model. The energy of Deltaron is obtained by considering the coupling of the ∆∆ and CC (hidden color) channels. The effects of various parameters on the Deltaron mass are also studied. It is shown that the mass of Deltaron is lower than the mass of ∆∆ but higher than the mass of ∆N π.