Testing Theories of Gravity via Black Hole Shadows

Data: 
14/08/2018 - 10:00 - 11:00
Local: 
Auditório 1

Testing Theories of Gravity via Black Hole Shadows

Yosuke Mizuno

ITP, Goethe University, Germany
 


Upcoming sub-millimetre VLBI images of Sgr A* and M87 carried out by the EHT Collaboration are expected to provide critical evidence for the existence of this supermassive black hole. In this work we assess our present ability to use EHTC images to determine if they correspond to a Kerr black hole as predicted by Einstein’s theory of general relativity or to a black hole in alternative theories of gravity. To this end, we perform GRMHD simulations and use GRRT calculations to generate synthetic shadow images of a magnetised accretion flow onto a Kerr black hole and a non-rotating dilaton BH, which we take as a representative solution of an alternative theory of gravity. Taking into account the  VLBI configuration of the 2017 EHT observation, we find that it could be difficult to distinguish between black holes from different theories of gravity, unless additional information (e.g. from orbiting pulsars or stars) were available.