Free Astronomy Magazine May-June 2019

7 The Event Horizon Telescope captures the first image of a black hole lenge which required upgrading and connecting a worldwide net- work of eight pre-existing tele- scopes deployed at a variety of chal- lenging high-altitude sites. These locations included volcanoes in Hawai`i and Mexico, mountains in Arizona and the Spanish Sierra Ne- vada, the Chilean Atacama Desert, and Antarctica. The EHT observations use a tech- nique called very-long-baseline inter- ferometry (VLBI) which synchronises telescope facilities around the world and exploits the rotation of our planet to form one huge, Earth-size telescope observing at a wavelength of 1.3 mm. VLBI allows the EHT to achieve an angular resolution of 20 micro-arcseconds — enough to read a newspaper in New York from a café in Paris. The telescopes con- tributing to this result were ALMA, T his video summarizes the historic feat of EHT researchers that have succeeded in getting the first direct visual evidence of a supermassive black hole and its shadow. [ESO] ! APEX, the IRAM 30-meter telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Al- fonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope. Petabytes of raw data from the tele- scopes were combined by highly spe- cialised supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Obser- vatory. European facilities and fund- ing played a crucial role in this worldwide effort, with the participa- tion of advanced European tele- scopes and the support from the European Research Council — partic- ularly a 14 million euros grant for the BlackHoleCam project. Support from ESO, IRAM and the Max Planck Soci- ety was also key. “This result builds on decades of European expertise in millimetre astronomy” , commented Karl Schuster, Director of IRAM and member of the EHT Board. The con- struction of the EHT and the obser- vations announced today represent the culmination of decades of obser- vational, technical, and theoretical work. This example of global team- work required close collaboration by researchers from around the world. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the US National Science Foundation (NSF), the EU’s European Research Council (ERC), and funding agencies in East Asia. “ESO is delighted to have sig- nificantly contributed to this result through its European leadership and pivotal role in two of the EHT’s com- ponent telescopes, located in Chile — ALMA and APEX,” commented ESO Director General Xavier Bar- cons. “ALMA is the most sensitive fa- cility in the EHT, and its 66 high- precision antennas were critical in making the EHT a success.” “We have achieved something pre- sumed to be impossible just a gener- ation ago,” concluded Doeleman. “Breakthroughs in technology, con- nections between the world’s best radio observatories, and innovative algorithms all came together to open an entirely new window on black holes and the event horizon.”