Free Astronomy Magazine January-February 2021

41 JANUARY-FEBRUARY 2021 ASTRO PUBLISHING thought to have formed from the collapse of the first stars, must have grown very fast to reach masses of a billion suns within the first 0.9 bil- lion years of the Universe’s life. But astronomers have struggled to ex- plain how sufficiently large amounts of “black hole fuel” could have been available to enable these ob- jects to grow to such enormous sizes in such a short time. The new-found structure offers a likely explanation: the “spider’s web” and the galaxies within it contain enough gas to pro- vide the fuel that the central black hole needs to quickly become a su- permassive giant. But how did such large web-like structures form in the first place? As- tronomers think giant halos of mys- terious dark matter are key. These large regions of invisible matter are thought to attract huge amounts of gas in the early Universe; together, T his artist’s impression shows the central black hole and the galax- ies trapped in its gas web. The black hole, which together with the disc around it is known as quasar SDSS J103027.09+052455.0, shines brightly as it engulfs matter around it. [ESO/L. Calçada] the gas and the invisible dark mat- ter form the web-like structures where galaxies and black holes can evolve. “Our finding lends support to the idea that the most distant and massive black holes form and grow within massive dark matter halos in large-scale structures, and that the absence of earlier detec- tions of such structures was likely due to observational limitations,” says Colin Norman of Johns Hopkins University in Baltimore, US, also a co-author on the study. The galaxies now detected are some of the faintest that current tele- scopes can observe. This discovery required observations over several hours using the largest optical tele- scopes available, including ESO’s VLT. Using the MUSE and FORS2 in- struments on the VLT at ESO’s Paranal Observatory in the Chilean Atacama Desert, the team con- firmed the link between four of the six galaxies and the black hole. “We believe we have just seen the tip of the iceberg, and that the few galax- ies discovered so far around this su- permassive black hole are only the brightest ones,” said co-author Bar- bara Balmaverde, an astronomer at INAF in Torino, Italy. These results contribute to our understanding of how supermassive black holes and large cosmic structures formed and evolved. ESO’s Extremely Large Tel- escope, currently under construction in Chile, will be able to build on this research by observing many more fainter galaxies around massive black holes in the early Universe using its powerful instruments. !