Gamma-Ray Burst Ring-shaped Jets And Their Afterglows Ming Xu Department of Astronomy, Nanjing University Gamma-ray Sky from Fermi: Neutron Stars and their EnvironmentHong Kong Collaborators: Yongfeng Huang, Siwei Kong Outline GRB jets Structure of ring-shaped jets Afterglows of ring-shaped jets Early rebrightening from ring-shaped jet Conclusions 2 Gamma-Ray Burst 3 Gamma-ray bursts are short and intense unpredictable flashes of gamma-ray photons. Light curve of GRB-complicated Millisecond Stellar scale 4 Center star Peculiar properties of GRB High redshiftGRB z=8.2 Nearby GRBGRB z= High luminosityGRB L iso =2.210 54 erg/s Naked GRBGRB Bm V =5.3 Ultra-relativisticGRB >1200 High engrgy photonGRB Bh=33.4 GeV Huge isotropic energyGRB CE iso =5.610 54 ergs 5 M c 2 =1.810 54 ergs GRBsIsotropic energy (ergs) GRB E iso =2.810 54 ergs GRB E iso =1.810 54 ergs GRB E iso =1.210 54 ergs GRB BE iso =1.310 54 ergs GRB E iso =1.910 54 ergs GRB CE iso =5.610 54 ergs GRB E iso =4.110 54 ergs GRB E iso =1.110 54 ergs Amati 08,09,10; Ghirlanda 08,09,10 E iso VS M c 2 6 Stellar scale 1. GRB Jets 7 GRB Jet Beaming Angle Gao & Dai 2010 ~ 3.4 f -1 ~ Intrinsic energy GRB Jet Models Uniform jet (UJ) Universal structured jet (USJ) Cylindrical jet (CJ) Gaussian jet (GJ) Two-component jet (TCJ) Fan shaped jet (FSJ) Ring shaped jet (RSJ) 9 jet GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Ring shaped jet Fan shaped jet 10 jet Most familiar GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Ring shaped jet Fan shaped jet 11 Not uniform GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Ring shaped jet Fan shaped jet 12 jet GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Ring shaped jet Fan shaped jet 13 jet GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Ring shaped jet Fan shaped jet 14 jet narro w wide GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Fan shaped jet Ring shaped jet 15 jet GRB Jet Models Uniform jet Universal structured jet Cylindrical jet Gaussian jet Two-component jet Fan shaped jet Ring shaped jet 16 ring hollow Granot 2005 GRB Jet Models 17 2. GRB ring-shaped Jets If GRB jet axis is precessing around the spin axis, there may be produced a ring-shaped jet. Fargion et al Aloy & Rezzolla 2006 Mizuno et al Quasi ring-shaped Jet 19 Sketch of ring-shaped jet Xu et al. 2008a 20 Evolution of a ring-shaped jet Xu et al. 2008a 21 Inner edge Outer edge RSJ Evolution of a ring-shaped jet Xu et al. 2008a 22 Inner edge Outer edge UJ Evolution of a ring-shaped jet 23 ISM Afterglows ring 3. Afterglow light curves of ring-shaped jet Xu et al. 2008a 24 ring UJ Line of sight on ring Effect of parameters on LC (1) Xu et al. 2008a 25 magnetic energy fractionelectronic energy fraction opening angle of the central cone observing angle Effect of parameters on LC (2) Xu et al. 2008a 26 Number density of ISMpower-low index of electron energy distribution Afterglows LC of ring-shaped jet Xu et al. 2008a X-ray band Radio (8.5Ghz) band 27 R-band Fit to afterglow of GRB A Xu et al. 2008b 28 4. Rebrightening from ring-shaped jet Xu et al. 2008a On the ring In hollow cone 29 Rebrightening VS Flare Chincarini et al. 2007Margutti et al >1 30 GRB t t Rebrightening from off-axis model Margutti et al GRB Line of sight Prompt emission? Early rebrightening of GRB Compare to off-axis conical jet Line of sight The ring-shaped jet model is superior over the normal off-axis conical jet model when considering the production of the intensive -ray radiation in the prompt GRB phase. 33 Xu & Huang 2010 Early rebrightenings from ring-shaped jets 34 Line of sight in the central axis of hollow cone Afterglow LC similar to conical jet Effect of parameters on LC Early rebrightenings of GRB afterglow may be resulted from ring-shaped jets Conclusions 35 Thank you!