Imaging black holes with the Event Horizon Telescope
Black holes have been described by Einsten's Theory of General Relativity already more than 100 years ago. In the late 60-ties astronomers discovered that real black holes could exist in the center of galaxies, including our own Galaxy. After many years of observations and research on black holes, in 2017 an Event Horizon Telescope has been constructed out of existing sub-millimeter telescopes to form an Earth size virtual observatory capable of resolving black hole shadow in the center of the our galaxy and in the center of galaxy M87. On April 10, 2019 we presented the first results from EHT, the first images of plasma emission produced near event horizon shadow around supermassvie in M87 galaxy (one of the images is shown above, image credit: EHT Collaboration.). The physical understading/interpretation of this observation require modeling appearance of black hole when it is surrounded by gas and magnetic fields.
Modeling black hole shadow
The ipole code allows to model the appearance of the black hole shadow. The synthetic images are produced assuming a plasma and magnetic fields configuration around a black hole and synchrotron emission. Then synchrotron photons are ray-traced towards the observer. The unique feature of ipole is that it is capable to track light polarization. Polarized component of radiation (Stokes Q,U,V) carries the information about geometry of magnetic fields responsible for synchrotron emission. Modeling the polarized electromagnetic counterparts of accreting black holes is the most promissing way to learn about magnetizm of compact objects. This study is crucial to find out, for example, how relativistic jets, that we do observe in many astrophysical systems, are launched and powered.