Imaging the event horizon of black holes

BlackHoleCam is a project funded by the European Research Council to finally image, measure and understand astrophysical black holes. BlackHoleCam Scientists as part of the Event Horizon Telescope Consortium contributed to obtain the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity.

A view of the M87 supermassive black hole in polarised light

The Event Horizon Telescope (EHT) collaboration, who produced the first ever image of a black hole released in 2019, has today a new view of the massive object at the centre of the Messier 87 (M87) galaxy: how it looks in polarised light. This is the first time astronomers have been able to measure polarisation, a signature of magnetic fields, this close to the edge of a black hole.
This image shows the polarised view of the black hole in M87. The lines mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole.

Credit: © EHT Collaboration

BlackHoleCam is a project funded by the European Research Council to finally image, measure and understand astrophysical black holes. BlackHoleCam Scientists as part of the Event Horizon Telescope Consortium contributed to obtain the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity.

The supermassive black hole at the centre of M87. Left: The black hole feeds on a swirling disc of glowing plasma, driving a powerful relativistic jet across several thousands of light years. Bottom right: Approaching the black hole, gravity is so strong that light is severely bent, creating a bright (almost circular) ring. The north–south asymmetry in the emission ring is produced by relativistic beaming and Doppler boosting (matter in the bottom part of the image is moving toward the observer) and is mediated by the black hole spin (which is pointing away from Earth and rotating clockwise). Gravitational lensing magnifies the apparent size of the black hole’s event horizon into a larger dark shadow. The emission between the photon ring and the event horizon is due to emitting plasma either in the accretion flow and/or at the footprint of the jet (this emission is generally too dim to be detected by the EHT). Top right: While the EHT can zoom in very close to the event horizon, down to scales of only 0.01 light years (or 3.7 light days), i.e., a region comparable to the size of our Solar System, the relativistic jet (extended across several thousand light-years) can be probed using ALMA intra-baselines, recorded during the EHT observations (greyscale image).