Transient sky and LSST Nicolas Leroy

Transient sky will be well covered in 2020 Large sets of instruments in 2020 SVOM Scientific prospects arXiv 1610.06892v1

Multi-messenger astronomy Timeline KM3NET - ORCA NB : ARCA have a similar timeline

Lot of physics behind SVOM Scientific prospects arXiv 1610.06892v1

Courtesy of G. Ghirlanda GRB orphan afterglows γ rays Courtesy of G. Ghirlanda N_orph ~ N_grb(2/theta2) ~300 orphan afterglows for each on-axis GRB!

GRB orphan afterglows The beaming angle of GRB jets remains a crucial issue, which impacts the energy budget of GRBs. “isotropic equivalent” energy Eiso is computed under the assumption that the source emits isotropically and spans 6 orders of magnitude from 1048 to 1054 erg. Due to beaming, the true energy radiated by GRB jets could be smaller by up to a factor 103, but the beaming angle has been measured for only a few GRBs. Determining the GRB progenitor nature. The observations of an orphan afterglow probe circumburst environment material less affected by the strong ionizing flux of the jet. Optical spectroscopy of GRB orphan afterglows is possibly a unique way to probe the pristine environment of the massive star GRB progenitor.

GRB orphan afterglows Ghirlanda+15 LSST is the best facility to detect orphan afterglows LSST offers a completely new method of detecting GRBs afterglows (for the first time independently of their detection in gamma-rays). LSST will detect the optical afterglows of on-axis and off-axis GRBs. Synergy LLST-SVOM to study the afterglows/orphan afterglow population

You are needed ! From current expectations LSST will provide up to 106 transients / night Nobody can absorb a so large sample What parameters can we determine on the nature of the source with your measurements ? Will help a lot to make decision in terms of ToO Plan of observation will allow only on exceptional astrophysics event a depointing Can we anticipate in advance the plan based on closed by galaxies ie up to maximum of binary neutron stars range with GW detectors for example ?

Let discuss together First point here We also organize a PNHE workshop 20-22 June 2017 in Orsay : https://ts2020.lal.in2p3.fr/ One session will be dedicated to LSST !