广西大学天体物理学科介绍

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General Picture of Gamma-Ray Bursts
GRBs and their afterglows are produced from extremely relativistic jets powered by the central engine.
V ≥ 0.9999c
1
Estimating the Initial Γ0 of GRB jets
9
Liso-Ep,z-Γ0 as a new GRB cosmology ruler?
Ejet-Ep relation (Ghirlanda + 2004)
Eiso-E源自文库-tjet relation (Liang & Zhang 2005)
Dai, Liang, & Xu 2004, ApJL; Liang & Zhang 2005, ApJ
Needing to geometric correction to Liso
Identifying the cosmic evolution of jet luminosity.

Liang + 2015; Xin + 2016
11
3. Our On-Going Observational Projec
10
Liso-Ep,z-Γ0 as a new GRB cosmology ruler?
Advantages:
A tighter relation than previous ones.
Issues:
Needing to be confirmed with LL-GRBs (moderate relativistic jets?)
Relation between afterglow onset and prompt gamma-rays
Optical afterglow onset is detected for 1/3 of GRBs
Onset peak luminosity is correlated with prompt gamma-ray luminosity.
Peng + 2014
Optical and X-ray afterglow Cartoon Lightcurves
X-ray Emission components
Optical Emission components
Zhang et al. 2006, ApJ; Li, Liang et al. 2012, ApJ
❖ Relation among the three parameters?
A tight Liso-Ep,z-Γ0 relation
GRB 060218: Γ0 ~ 2.3 (Soderberg + 2006)
Liang + 2015, ApJ
8
A tight Liso-Ep,z-Γ0 relation
30s
trigger
Project
10m
Identification and early
Spectrum、 redshift
photometry
hours Late photometry
GWAC/GRB alert 60/80cm Telescope2m telescope
Examples of Our Monitoring Results
Yonetoku et al. 2004, ApJ
Lu et al. 2012, ApJ
Eiso (or Liso)-Ep vs. Eiso (or Liso)-Γ0 Relation
Amati et al. 2012, IJMPD
Liang et al. 2010, ApJ
❖ Is the large intrinsic dispersion of pair correlations due to missing of the third part?
Eiso (or Liso)-Ep Relation
These relations was found with GRBs detected with BeppoSAX and also confirmed with Swift/BAT and Fermi/GBM GRBs.
Amati et al. 2012, IJMPD
Liang et al. 2010, ApJ
Eiso (or Liso)-Γ0 Relation
A tight correlation between the Eiso and the Lorentz factor of GRB fireball
Liang et al. 2010,2013, ApJ; LV et al. 2012, ApJL
❖With the fireball deceleration time(e.g.,Sari & Piran 1999)
❖With the "compactness" argument: (e.g.,Lithwick & Sari 2001)
Liang + 2010
Tang + 2014
❖With the photosphere radiation: (e.g. Zou + 2015)
GRB trigger Follow-up
Hu+ 2014
GRBs
Flux
Optical Tels
magnitude
R=13 Mini-GWAC
R=16 GWAC R=19 60/80cm
Singer+2012
R=21 iPTF
-400s -200s 0 100s 5m 1h 1d
Our Current Optical Monitoring
Double check with GRBs whose Γ0 are derived from the spectral cutoff energy observed with Fermi/LAT.
GRB 060218: Γ0 ~ 2.3 (Soderberg + 2006)
Liang + 2015, ApJ
Mini-GWAC upper limit : M=13.2
GRB 160131A
B, V, R, I observations with our 60/ 80 cm telescopes in Xinglong Observatory.
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