Hunting GRB Early Optical Emission with TAOS Telescopes

Kuiyun Huang Academia Sinica, Institute of Astronomy and Astrophysics

(ASIAA),Taiwan

TAOS ProjectTAOS Project(Taiwan-America Occultation Survey)

No significant events were found in the first two years (2005-2006) 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 : 5000-7000 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 TAOS GRB Alert System

• Exposure time : 0.2s, 1s, 5s, 25s• Follow-up time : 30 minutes

TAOS GRB observations in 2006-2007TAOS GRB observations in 2006-2007

(1) GRB 071010B Duration : 35s Afterglows : XT, OT Redshift : 0.947 Response telescopes :

TAOSA(1s),TAOSB(5s),TAOSD(25s)

Response time : 52s after trigger 38s after alert Fastest response in this event Time coverage : 63-230 s

(2) GRB 071112C Duration : 15s

Afterglows : XT, OT

Redshift : 0.823

Response telescopes : TAOSA(1s),TAOSB(5s)

Response time :

94s after trigger

41s after alert

Time coverage : 94-4000 s

GRB 071010B GRB 071010B (Wang, Schwamb & Huang et al. 2008)(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 sInitial Lorentz factor Γ0 ~ 164 (ISM), Γ0 ~ 31 (Wind)

GRB 071112CGRB 071112C

α = -0.81+/- 0.02

α = -1.36+/- 0.01

α = -1.6+/- 0.1

(Stratta et al. 2007)

Advantages for GRB Observations 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 Probe early optical emission of GRBsGRBs

T90 =520s T90 =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 (2005TAOS Observing Hours (2005––2006)2006)

TAOS TelescopesTAOS Telescopes

TAOS Shutter-less Zipper ModeTAOS Shutter-less Zipper Mode

row-block(transient state)

CCD snapshotw. time tag(1 to 4)

row-block(steady state)

a more realistic case…

charge transfer(downward)

block readout

TAOSzipper image(a stack of row-blocks)

data taken on 21 February 2004 (UTC)

TAOS ZIPPER MODE IMAGE

GRB 050820A : The first case shows the GRB 050820A : The first case shows the two two opticaloptical components components

T90 = 85s

initial burst

major burst

Afterglow emission

Prompt optical emission +Afterglow emission

Vestrand et al. Nature 2006 422, 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

THE TAOS TEAM

Institute of Astronomy & Astrophysics and Institute of Earth Sciences, Academia Sinica, TaiwanTyphoon Lee(IES PI), Chi-Yuan(IAA PI), Sun-Kun King,

Andrew Wang, Shang-Yu Wang, Chih-Yi WenInstitute of Astronomy, National Central University, Taiwan

Wen-Ping Chen, Yung-Shin Chang, Soumen Mondal, Kiwi ZhangHarvard-Smithsonian Center for Astrophysics, USA

Charles Alcock, Matthew Lehner, Federica B. Bianco, Rahul DaveThe Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, USA

Kem CookYonsei University, Department of Astronomy, South Korea

Yong-Ik Byun

Department of Physics and Astronomy, University of Pennsylvania, USA Joseph GiammarcoUniversity of California, Berkeley, USA Imke de Pater, John RiceStanford Linear Accelerator Center, USA Stuart MarshallSteward Observatory, The University of Arizona, USA Tim AxelrodAmes Research Center, National Aeronautics & Space Administration, USA Jack Lissauer