Free Astronomy Magazine July-August 2023

14 JULY-AUGUST 2023 than what could be observed with the EHT. These new observations of M87’s black hole were conducted in 2018 with the GMVA, which consists of 14 radio-telescopes in Europe and North America. In addition, two other fa- cilities were linked to the GMVA: the Greenland Telescope and ALMA, of which ESO is a partner. ALMA con- sists of 66 antennas in the Chilean Atacama desert, and it played a key role in these observations. The data collected by all these tele- scopes worldwide are combined using a technique called interferom- etry, which synchronises the signals taken by each individual facility. But to properly capture the actual shape of an astronomical object it’s impor- tant that the telescopes are spread all over the Earth. The GMVA tele- scopes are mostly aligned East-to- West, so the addition of ALMA in the Southern hemisphere proved es- sential to capture this image of the jet and shadow of M87’s black hole. “Thanks to ALMA’s location and sensitivity, we could reveal the black hole shadow and see deeper into the emission of the jet at the same time,” explains Lu. Future observations with this net- work of telescopes will continue to unravel how supermassive black holes can launch powerful jets. “We plan to observe the region around the black hole at the centre of M87 at different radio wave- lengths to further study the emis- sion of the jet,” says Eduardo Ros from the Max Planck Institute for Radio Astronomy. Such simultane- ous observations would allow the team to disentangle the compli- cated processes that happen near the supermassive black hole. “The coming years will be exciting, as we will be able to learn more about what happens near one of the most mysterious regions in the Universe,” concludes Ros. T his image shows the jet and shadow of the black hole at the centre of the M87 galaxy together for the first time. The observations were obtained with telescopes from the Global Millimetre VLBI Array (GMVA), the Atacama Large Mil- limeter/submillimeter Array (ALMA), of which ESO is a partner, and the Greenland Telescope. This image gives scientists the context needed to understand how the powerful jet is formed. The new observations also revealed that the black hole’s ring, shown here in the inset, is 50% larger than the ring observed at shorter radio wavelengths by the Event Horizon Telescope (EHT). This suggests that in the new image we see more of the material that is falling towards the black hole than what we could see with the EHT. [R.-S. Lu (SHAO), E. Ros (MPIfR), S. Dag- nello (NRAO/AUI/NSF)] The video below comments on the new image. [ESO] ASTRO PUBLISHING The size of the ring observed by the GMVA network is roughly 50% larger in comparison to the Event Horizon Telescope image. “To un- derstand the physical origin of the bigger and thicker ring, we had to use computer simulations to test dif- ferent scenarios,” explains Keiichi Asada from the Academia Sinica in Taiwan. The results suggest the new image reveals more of the material that is falling towards the black hole !