10.01.2019 - By Dr Rajesh Verma
A doctoral student at the University of Arizona, Lia Medeiros develops mathematical models that will enable researchers to confront Einstein's theory of general relativity against the most powerful monsters in nature: supermassive black holes such as Sgr A *, which is hidden in the center of the Milky Way. Medeiros has developed a diagnostic tool that astronomers can use to compare future observations of supermassive black holes from the Event Horizon telescope to predictions of mathematical models of these swirls of space and time. "We want to test if the black holes observed in space behave as we wish," said Medeiros, who will present his thesis work (including three published papers and a fourth to be submitted to the Astrophysical Journal) during an oral session at the Meeting of the American Astronomical Society. "If we detect a deviation from our expectations, we can fundamentally change our thinking about black holes and gravity itself."
Astronomers believe that the shape of the shadow is a property of the geometry of space-time and does not depend on accretion or astrophysical effects. Medeiros uses computer simulations of the shadow of black holes, a diagnostic function predicted by general relativity, to test Kerr's metric, a solution to Einstein's equations meant to describe the characteristics of black holes in space. She simulated a large number of black hole shadows deviating from Kerr and developed a method of using future observations of the Event Horizon telescope on the shadow of the black hole to impose constraints on these deviations.
"If the black holes meet our expectations, the method I developed will also allow us to quantify how far a theory can be from these expectations while remaining consistent with the data. eliminate many other theories, "says Medeiros. "I'm developing tools so that we can actually use EHT observations to see if Sgr A * is described by Kerr's metric," she added. Medeiros' work is part of the Horizon Telescope Event, or EHT, an international collaboration that attempts to represent for the first time the supermassive black hole in the center of our galaxy.