Hunting GRB Early Optical Emission with TAOS Telescopes Kuiyun Huang Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA),Taiwan

TAOS Project TAOS Project (Taiwan-America Occultation Survey)

No significant events were found in the first two years ( )  Present upper bound to the size of KBO ( 0.5km < D < 10km)  Construct TAOS 2 project Zhang et al. 2008

Special Features of TAOS project Four robotic telescopes (50cm, F/1.9 Cassegrain) 2k x 2 k CCD Camera (EEV CCD 42-40) Field of View ~ 1.7 degree x 1.7 degree Pixel size ~ 3 “ Filter : A (near R band ) Observational Mode – Zipper mode (0.2 sec exposure) - Stare mode Nearly real-time processing /correlation among telescopes Response to GCN (GRB Coordinate Network) alert in 1 min

TAOS GRB Alert System Exposure time : 0.2s, 1s, 5s, 25s Follow-up time : 30 minutes

TAOS GRB observations in (1) GRB B  Duration : 35s  Afterglows : XT, OT  Redshift :  Response telescopes : TAOSA(1s),TAOSB(5s),TAOSD(25s)  Response time : 52s after trigger 38s after alert  Fastest response in this event  Time coverage : s (2) GRB C  Duration : 15s  Afterglows : XT, OT  Redshift :  Response telescopes : TAOSA(1s),TAOSB(5s)  Response time : 94s after trigger 41s after alert  Time coverage : s

GRB B (Wang, Schwamb & Huang et al. 2008) No significant correction with the prompt  -ray emission Optical afterglow light curve up to 2 days after the burst Use Equations of Molinari et al. (2007) Tpeak ~ 158 s Initial Lorentz factor Γ0 ~ 164 (ISM), Γ0 ~ 31 (Wind)

GRB C α = / α = / α = -1.6+/- 0.1 (Stratta et al. 2007)

Advantages for GRB Observations (1) Fully automated observing system -- Telescopes can have quick response to GRBs -- Alert software has established to manage GRB alerts and send observing commands to telescopes. (2) Four 50cm-telescopes at same site -- Follow-up with different exposure time -- Obtain high time resolution light curve in early afterglow phase. Bootes

Two components of optical emission during the first few minutes (Vestrand et al. 2006) (a) The prompt optical emission  Correlated with prompt gamma-ray emission.  Could probe isolated jet from the surrounding medium (b) The early optical afterglow emission  Uncorrelated with prompt gamma-ray emission  Strongly depends on the nature of medium Probe early optical emission of GRBs T 90 =520s T 90 =110s

TAOS

照片由中央大學提供 ( 拍攝時間 : 2007年八月 ) TAOSA, TAOSB TAOSC TAOSD Lulin 1-m 40cm Thank You!

TAOSA and TASOB

TAOS Observing Hours (2005–2006)

TAOS Telescopes

TAOS Shutter-less Zipper Mode row-block (transient sta te) CCD snapshot w. time tag (1 to 4) row-block (steady state ) a more realistic case… charge transfer (downward) block readout TAOS zipper image (a stack of row-blocks)

data taken on 21 February 2004 (UTC) TAOS Z IPPER M ODE I MAGE

GRB A : The first case shows the two optical components T 90 = 85s initial burst major burst Afterglow emission Prompt optical emission + Afterglow emission Vestrand et al. Nature , 172 RAPTOR KONUS (1) Prompt emission broad-band spectra could constraint evolution of jet itself. (2) Afterglow emission Afterglow of secondary energy release could merger the fading primary afterglow  probe evolution of the interaction  how the GRB environment is modified

T HE TAOS T EAM Institute of Astronomy & Astrophysics and Institute of Earth Sciences, Academia Sinica, Taiwan Typhoon Lee(IES PI), Chi-Yuan(IAA PI), Sun-Kun King, Andrew Wang, Shang-Yu Wang, Chih-Yi Wen Institute of Astronomy, National Central University, Taiwan Wen-Ping Chen, Yung-Shin Chang, Soumen Mondal, Kiwi Zhang Harvard-Smithsonian Center for Astrophysics, USA Charles Alcock, Matthew Lehner, Federica B. Bianco, Rahul Dave The Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, USA Kem Cook Yonsei University, Department of Astronomy, South Korea Yong-Ik Byun Department of Physics and Astronomy, University of Pennsylvania, USA Joseph Giammarco University of California, Berkeley, USA Imke de Pater, John Rice Stanford Linear Accelerator Center, USA Stuart Marshall Steward Observatory, The University of Arizona, USA Tim Axelrod Ames Research Center, National Aeronautics & Space Administration, USA Jack Lissauer