To the Transient Universe and Beyond
Scientific Program
Thursday 3rd September, 2020
Chair: Jean-Luc Atteia
8:30/15:30 (10+5) Bruce Gendre ICARE: a tool to increase follow-up success
ICARE is a set of tools made and used by the GRANDMA collaboration during the LVC O3 run, aimed at coordinating observations among more than 20 telescopes. In this short talk, I will biefly explain it, and what it can bring in this era of transient astronomy.
 
VIDEO
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The study of early optical emission of gamma-ray bursts give an opportunity to understand the first stages of these events and the inner parts of central engines of GRBs. We compiled observations of early optical GRBs detected from the literature with TAROT and COATLI telescopes and presented 2 light curves more (GRB 180706A and GRB 180812A). We found an empirical early optical light curve which is very similar to the X-rays one. Moreover, we present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of around 150 events at $t+1000$. We discuss these results for the physical implications to the science of GRBs and specifically for dark GRBs. We illustrated the current scenario for the future arrival of the SVOM mission and the GFT follow-up instruments. VIDEO
In this short talk, I will briefly present the GRBase project which aims at collecting a large amount of multi wavelength data obtained the last two decades for both the prompt and afterglow emission phases of the Gamma-Ray Bursts. In addition, GRBase will provide tools to perform quick SED and light curve fitting to ease the scientific analysis. In my talk, I will put in perspectives the capabilities of the Colibri telescope with the past observations of GRBs made by various facilities this last 2 decades. I will show how the Colibri telescope is a unique facility and how it will contribute to enhance the scientific returns of the SVOM mission based on the experience we have so far with previous GRB missions like Swift. VIDEO


9:20/16:20 COFFEE BREAK
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9:35 9:35/16:35 (10+5) Robin Marron Optimization of observation strategy for COLIBRI
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Presenting brief results on the optimization of COLIBRI's strategy of observation : sequences of filter and exposure time to 1- Detect the more GRB possible 2- Get the best estimation of the photometric redshift of the GRB Worked done in the context of an internship supervized by Stéphane BASA (LAM). VIDEO
The merger of a binary neutron star system can result in the emission of gravitational waves, a highly dense and magnetized environment, and the launch of a collimated relativistic jet which eventually produces a short gamma-ray burst (SGRB). Although the evolution of a jet-SGRB has been studied through different media the evolution through a magnetized medium remains to be fully understood. Therefore, in order to understand the importance of the medium's magnetic field, we studied the evolution of a series of SGRB-jets through media with different $\textbf{B}$ using two-dimensional magneto-hydrodynamic relativistic numerical simulations. Specifically, we follow the evolution of jets-SGRB with $L_ {j}$ and $\theta_ {j}$variables through a medium with different distributions of $\textbf{B}$ and magnitudes of $\textbf{B}$.


 VIDEO
10:05/10:05 (10+5) Ana Lourdes Juárez Boosted-frame simulations of gamma-ray bursts


Numerical studies of gamma-ray bursts are challenging, mainly due to the very large scales and Lorentz factors involved. Indeed, with Lorentz factors of about 500-1000, a small error in the determination of the velocity leads to very large errors in the Lorentz factor. In this work, we show that ultra-relativistic jets can be solved much more efficiently by employing boosted frames. We present our implementation of a boosted frame into the special relativistic, hydrodynamic code Mezcal. The boosted frame moves in the direction of propagation of the jet, such that a jet with a Lorentz factor of 1000 in the lab frame, moves with a Lorentz factor of 22 in the boosted frame (which largely reduce numerical problems). By using the boosted frame, we present the first multi-dimensional study of the early dynamical evolution of the jet. We analyse in particular the formation of the reverse shock and the lateral expansion of the jet, and we discuss the observational implications.

 VIDEO
10:20/17:20 COFFEE BREAK
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Black hole accretion theory is an important topic in astrophysics since it is one of the main ingredients involved in the physics of several high-energy phenomena. In particular, the launching of astrophysical jets and outflows is assumed to be related to gas being accreted onto a central massive object (CMO)and remains an open issue that is still not fully understood. In this talk, I will address this problem by presenting an extension model of Bondi's classical spherical accretion problem. For this model, a fraction of the material that is accreted by the CMO is transformed into an inflow-outflow bipolar structure that may, under appropriate conditions, account for the inner engine behind a jet-launching process, even without the intervention of magnetic fields. VIDEO


10:50/17:50 DISCUSSION VIDEO
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