Into Supermassive Black Holes. Cutting-Edge Research by the Event Horizon Telescope

I
n 2019, the international collaboration of the 
Event Horizon Telescope (EHT) published the 
first “photographs” of the supermassive black 
hole at the center of the M87 galaxy (see p. 
XX in this issue and TEHPC, 2019a). These 
images confirmed the model predictions based 
on Albert Einstein’s theory of general relativity 
by showing the presence of a central dark shadow 
surrounded by a bright ring associated with a 
so-called photon sphere (TEHPC, 2019b; figure 
1, left). A few years later, the EHT collaboration 
published images of the same black hole in 
polarized light, which revealed the presence of 
prominent magnetic fields near the event horizon 
and allowed to constrain the physical conditions 
of the surrounding plasma (TEHPC 2021a, 2021b,