Free Astronomy Magazine November-December 2024

8 NOVEMBER-DECEMBER 2024 ASTRO PUBLISHING was discovered in the gas-rich galaxy MCG-03-34-64. Astronomers using radio telescopes have ob- served one pair of binary black holes in even closer proximity than in MCG-03-34-64, but without con- firmation in other wavelengths. AGN binaries like this were likely more common in the early universe when galaxy mergers were more frequent. This discovery provides a unique close-up look at a nearby ex- ample, located about 800 million light-years away. The discovery was serendipitous. Hubble’s high-resolution imaging revealed three optical diffraction spikes nested inside the host galaxy, indicating a large concentration of glowing oxygen gas within a very small area. “We were not expecting to see something like this,” said Anna Trindade Falcão of the Center for Astrophysics | Harvard & Smith- sonian in Cambridge, Massachu- setts, lead author of the paper published in The Astrophysical Jour- nal . “This view is not a common oc- currence in the nearby universe, and told us there’s something else going on inside the galaxy.” Diffraction spikes are imaging arti- facts caused when light from a very small region in space bends around the mirror inside telescopes. Falcão’s team then examined the same galaxy in X-rays light using the Chandra observatory to drill into what’s going on. “When we looked at MCG-03-34-64 in the X-ray band, we saw two separated, powerful sources of high-energy emission co- Hubble and Chandra find supermassive black hole duo L ike two Sumo wrestlers squar- ing off, the closest confirmed pair of supermassive black holes have been observed in tight proxim- ity. These are located approximately 300 light-years apart and were de- tected using NASA’s Hubble Space Telescope and the Chandra X-ray Ob- servatory. These black holes, buried deep within a pair of colliding galaxies, are fueled by infalling gas and dust, causing them to shine brightly as ac- tive galactic nuclei (AGN). This AGN pair is the closest one de- tected in the local universe using multiwavelength (visible and X-ray light) observations. While several dozen “dual” black holes have been found before, their separations are typically much greater than what by NASA − Ray Villard