Gamma-Ray Burst Ring-shaped Jets And Their Afterglows

Ming XuDepartment of Astronomy, Nanjing

University2010.06.22

Gamma-ray Sky from Fermi: Neutron Stars and their Environment—Hong 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

3Gamma-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 redshift GRB 090423 z=8.2

Nearby GRB GRB 980425 z=0.0085

High luminosity GRB 080607 Liso=2.2×1054 erg/s

“Naked GRB” GRB 080319B mV=5.3

Ultra-relativistic GRB 090510 Γ>1200

High engrgy photon GRB 090902B hν=33.4 GeV

Huge isotropic energy GRB 080916C Eiso=5.6×1054 ergs

5

M⊙c2=1.8×1054ergs

GRBs Isotropic energy (ergs)

GRB 990123 Eiso=2.8×1054 ergs

GRB 000131 Eiso=1.8×1054 ergs

GRB 050904 Eiso=1.2×1054 ergs

GRB 080319B Eiso=1.3×1054 ergs

GRB 080607 Eiso=1.9×1054 ergs

GRB 080916C Eiso=5.6×1054 ergs

GRB 090323 Eiso=4.1×1054 ergs

GRB 090510 Eiso=1.1×1054 ergs

Amati 08,09,10; Ghirlanda 08,09,10

Eiso VS M ⊙ c2

6

Stellar scale

1. GRB Jets

7

GRB Jet Beaming Angle

Gao & Dai 2010

<θ> ~ 3.4°

f-1~ 1100

8

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

θ jet

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Ring” shaped jet

“Fan” shaped jet10

jet

Most familiar

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Ring” shaped jet

“Fan” shaped jet11

Not uniform

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Ring” shaped jet

“Fan” shaped jet12

jet

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Ring” shaped jet

“Fan” shaped jet13

jet

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Ring” shaped jet

“Fan” shaped jet14

jetnarrow

wide

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Fan” shaped jet

“Ring” shaped jet15

jet

GRB Jet Models

Uniform jet

Universal structured jet

Cylindrical jet

Gaussian jet

Two-component jet

“Fan” shaped jet

“Ring” shaped jet16

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. 200618

Aloy & Rezzolla 2006 Mizuno et al. 2008

Quasi ring-shaped Jet

19

Sketch of ring-shaped jet

Xu et al. 2008a20

Evolution of a ring-shaped jet

Xu et al. 2008a21

Inner edge

Outer edge

RSJ

Evolution of a ring-shaped jet

Xu et al. 2008a22

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. 2008a24

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 coneobserving angle

Effect of parameters on LC (2)

Xu et al. 2008a26

Number density of ISM power-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 050820A

Xu et al. 2008b28

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. 2010

>1

30

GRB 081028

t

Δt

Rebrightening from off-axis model

Margutti et al. 2010

31

GRB 081028

Line of sight

Prompt emission?

Early rebrightening of GRB 070208

http://www.swift.ac.uk/xrt_curves/00259714/ 32

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 γ-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!