Gamma-Ray Burst Optical Observations with AST3

1. 2015 International Collaboration Meeting on Antarctic Survey Telescopes Gamma-Ray Burst Optical Observations with AST3 Xue-Feng Wu Chinese Center for Antarctic Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences 2015, March 9, Hong Kong

2. Why GRB optical observations so important? absorption lines in afterglow spectrum host galaxy emission lines GRB 970508 z=0.835 (t~2.3day) (t~6-11months) Bloom et al., 2001, ApJ, 554, 678 Metzger et al., 1997, Nature, 387, 878 First of all, redshift! -> distance -> luminosity/energy

3. Importance of GRB optical observations (not complete) constraining the initial physical parameters of GRB fireballs – AST3! diagnosing the circum-burst environments – AST3! exploring the structure of GRB jets – AST3! (long) GRB – supernova associations –AST3? obtaining the host galaxy properties (morphology, star-forming, metallicity, etc.) probing the high-redshift Universe (Pop III stars, re-ionization history) with high-z GRBs - KDUST correlations, standard candles, cosmography? – AST3!

4. GRB central engine Constraining the initial physical parameters of GRB fireballs shocked ejecta - reverse shock shocked ISM -forward shock Peak of reverse shock emission: -> initial Lorentz factor (usually 100-1000) -> ISM density (typically 0.001 – 10 /cm^3) forward shock reverse shock Akerlof et al., 1999, Nature, 398, 400

5. GRB central engine Constraining the initial physical parameters of GRB fireballs shocked ejecta - reverse shock shocked ISM -forward shock forward shock GRB 140311A reverse shock too weak magnetized ejecta? Peak of forward shock emission: (Liang et al. 2010, for a large sample) -> initial Lorentz factor (usually 100-1000) -> ISM density (typically 0.001 – 10 /cm^3) Courtesy: David Coward, Zadko telescope

6. GRB central engine diagnosing the circum-burst environments forward shock log n log flux ISM shallower log t log R log flux wind log n steeper n R^-2 log t log R

7. GRB central engine diagnosing the circum-burst environments reverse shock forward shock Light curve comparison ISM: more sharp Wind: more shallow

8. diagnosing the circum-burst environments wind bubble of a Wolf-Rayet star Afterglow light curves (theory) n(R) free wind -> shocked regions -> ISM Geng, Wu, Li, Huang & Dai, 2014, ApJ small wiggles/rebrightening in the light curve observational requirement: continuous and dense -> AST3, Yes!

9. exploring the structure of GRB jets two scenarios for jet breaks Woosley, Nature, 414, 853 (2001) jet signature Harrison et al (1999) Piran, Science, 295, 986(2002) jet break time -> jet angle -> true energy of GRB!

10. exploring the structure of GRB jets 2nd jet 1st jet GRB 080319B Racusin, Karpov, Sokolowski, Granot, Wu, et al., 2008, Nature Huang, Wu, Dai, Ma & Lu, 2004, ApJ two-component jet model

11. correlations, standard candles, cosmography? jet Ep E,jet Ghirlanda-Relation Briggs et al et al. 1999; Ghirlanda et al. 2004; Dai et al. 2004

12. correlations, standard candles, cosmography? Using Ghirlanda-Relation Dai et al. 2004

13. correlations, standard candles, cosmography? tjet Ep Eiso Liang-Zhang Relation Briggs et al et al. 1999; Liang & Zhang 2005

14. correlations, standard candles, cosmography? Using Liang-Zhang Relation Wei, Wu, & Melia 2013, ApJ

15. GRB research with AST3 Regular GRB optical observation GRB orphan afterglow survey Merger-nova optical observation

16. regular GRB optical observation IPrompt phase and early afterglow • optical counterparts of prompt GRBs • early optical afterglows IILate optical observation • light curve jet breaks • origin of chromatic afterglows IIIGRB-SN associations • progenitors and explosion mechanisms prompt/quick response (minutes to hours) deep limit magnitude

17. Long GRB optical afterglow lightcurves MW dust extinction corrected AST3limit magnitude Kann, et al., 2010, ApJ, 720, 1513

18. Peak Mag vs. Peak Time

19. orphan afterglow survey I、off-axis GRBs： jet, radiation is relativistic beamed on-axis： prompt GRB afterglow off-axis： jet decelerates beaming effect decreases orphan afterglow true GRB rate ! true GRB energy ! II、failed GRBs： less energetic (lower Lorentz factor), less gamma-ray released, even undetectable on-axis： orphan afterglow

20. Merger-nova optical observation: EM signals for a BH post-merger (NS-NS) product SGRB Multi-band transient ~hours, days, weeks, or even years dimmer X-ray counterpart Li-Paczyński Nova Li & Paczyński, 1998 Opical flare ~ 1 day Ejecta-ISM shock Nakar& Piran, 2011 Radio ~years Metzger & Berger, 2012

21. Merger-nova optical observation: EM signals for a ms magnetar post-merger (NS-NS) product Jet-ISM shock (Afterglow) SGRB Late central engine activity ~Plateau & X-ray flare SGRB Magnetic Dissipation X-ray Afterglow X-ray Radio Optical X-ray Ejecta Zhang, 2013 1000 ~10000 s Photosphere emission Shocked ISM X-ray Optical and soft X-ray transient ~ days, weeks Yu, Gao &Zhang, 2013 MNS Ejecta-ISM shock with Energy Injection (EI) Poynting flux Multi-band transient ~hours, days, weeks, or even years Gao, Ding, Wu, Zhang & Dai, 2013 Wu et al. 2014; Wang & Dai, 2013

22. GRB research with infrared CCD

23. Dust Extinction

24. Origin of dark GRBs Dust extinction ? High-redshift GRBs? Intrinsically dark?

25. high-z or high extinction? photometric z~9.4，the most distant stellar object ever detected？

26. Thank You!