Prochain séminaire SCOPI mardi 11 juin à 16h - Thé et café servis à 15h45  
Le prochain séminaire SCOPI aura lieu le mardi 11 juin à 16h à l'auditorium Pierre Lehmann, Bât 200, campus universitaire d'Orsay. "First explorations of Sgr A* at the event horizon scale and first tests of general relativity with GRAVITY " Orateur: Guy Perrin (LESIA- Observatoire de Paris)
Mardi 11/06/2019

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The existence of black holes has been predicted for a long time, even before general relativity was sketched by Albert Einstein. Their extreme compactness makes them difficult to explore on spatial scales close to the event horizon.  
Sagittarius A*, at the center of the Galaxy, is the black hole with the largest angular size. A collaboration of European astronomers has built the GRAVITY instrument for the Very Large Telescope Interferometer of ESO to test the black hole nature of 
Sgr A* thanks to observations in the infrared at unprecedented spatial scales. General relativity can consequently also be tested at these scales in an extreme regime of 
gravity.  
I will present the detection of gravitational redshift with the star S2, the closest star 
known to Sgr A*. I will also present the first measurements of orbits of infrared flares occurring near the event horizon. I will conclude on the promising prospects of 
GRAVITY. 

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A. Sene, dépêche du 29/05/2019

 

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