Bruce Gendre Osservatorio di Roma / ASI Science Data Center Recent activities from the TAROT/Zadko network

The TAROT/Zadko Network Set of 3 robotic telescopes France (20 cm diameter) Chile (20 cm diameter) Australia (1m diameter) Aims GRB studies Space debris monitoring GW source detection Variable object survey 105 GRB observed so far 21 during prompt phase 35 detections

GRB A Swift trigger Circumpolar burst, visible all night long Redshift : 2.22 Global characteristics: Long burst T90 = 257s Spectral classification as X-ray Rich Nearly perfect follow-up Robotic telescopes (TAROT) activated during prompt phase mid-size instruments (0.5-1m) continued the follow-up for days large instruments (8+m) used at late time wide spectral coverage (far IR to X-ray)

Observations Gendre et al. 2011

Jet break At bin 11 X-ray and optical decay are: 1.identical 2.asymptotic to the same value 3.decay index ~ 2.3 Jet effect Break is progressive p = 2.3 θ = 2.1°

Optical flare Fast rising optical flare, not seen in X-rays Rise slope ~ t 5 Peak time ~ 1000 sec Interpretation : Reverse shock in thin shell The prompt GRB and the afterglow are temporally distinct Allows calculating the Lorentz factor Γ = 125

Optical flare Why this burst is unique: 1.low density 2.Magnetized fireball 3.very low Lorentz factor

Optical and Gamma-ray temporal correlation in the prompt very good correlation between optical and gamma-ray light curves Poor correlation between optical and X-ray light curve Optical and gamma-ray bands are due to the same mechanism ? An extra-component in X-ray ?

X-to-γ spectra require two breaks at few keV and 220 keV. Optical data do not agree with this ! Optical-Gamma ray data can be fit with the Band model But X-ray data are clearly not in agreement Optical and Gamma-ray prompt spectra

Internal shock Late internal shock Normal afterglow Jet effect Reverse shock The model in image: GRB110205A Gendre et al. 2011

GRB A Gendre et al., Science in prep Burst detected by Swift Also observed by Konus-Wind Duration of the gamma-ray even : ~ s Followed by XRT Sharp decay (high latitude emission) T burst ~ s Observation by other instruments XMM TAROT/Zadko

Extra long bursts in past Long bursts usually do not last long Mean time is 20 s ! Only 5 cases with duration > s GRB (BATSE) GRB B (Konus-Wind) GRB (Swift) GRB A (swift) GRB A (Swift) Obvious solution: Very high redshift burst Not a real GRB Golenetskii et al Z = 1.0 Z = 10

Any other clue ? Thermal component GRB and GRB A have strong thermal component GRB A not However, presence of a second component in the XMM Spectrum

Any other clue ? Stratta et al. In preparation XMM-Newton spectra, 10 ks integration time, during steep decay

Thermal component GRB and GRB A have strong thermal component GRB A not However, presence of a second component in the XMM Spectrum Faint thermal component at high energy (> 7 keV) Power law compatible with an Inverse Compton emission from the prompt Afterglow luminosity Under luminous afterglow Compatible with the idea to radiate most of the energy in the prompt phase using only internal shocks Any other clue ?

And so ? With the data in hands, it is difficult to conclude… No host galaxy info No large follow-up despite the "Swift burst of interest" label … but we can propose some crude hypotheses A very high rotation of a giant star (see Swift J case) ? A HMXB in a common envelop stage (with the neutron star located at the "correct" depth in the star) ? An HMXB going into the second supernovae ? Dear theoretician friends, please call me

Conclusion The TAROT/Zadko network is fine TAROT-La Silla went under refurbishment last year Zadko will move into a new building this year with a new camera and a low-resolution spectrometer Bursts are still observed GRB A This is an archetypal burst with all fireball component visible and, actually, observed We need more friendly burst like this to understand the model GRB A This is the longest burst ever recorded It is far less theoretician friendly But far more interesting for observing dude like me !