Free Astronomy Magazine March-April 2025

42 MARCH-APRIL 2025 ASTRO PUBLISHING A ctive galaxy 1ES 1927+654, cir- cled, is located 270 million light- years away and harbors a central black hole weighing about 1.4 million solar masses. [Pan-STARRS] intensive observations using the NRAO’s (National Radio Astronomy Observatory) VLBA (Very Long Base- line Array) and other facilities. The VLBA, a network of radio telescopes spread across the U.S., combines sig- nals from individual dishes to create what amounts to a powerful, high- resolution radio camera. This allows the VLBA to detect features less than a light-year across at 1ES 1927+654’s distance. Radio data from February, April, and May 2024 reveals what appear to be jets of ionized gas, or plasma, ex- tending from either side of the black hole, with a total size of about half a light-year. Astronomers have long puzzled over why only a fraction of monster black holes produce power- ful plasma jets, and these observa- tions may provide critical clues. “The launch of a black hole jet has never been observed before in real time,” Meyer noted. “We think the outflow began earlier, when the X- rays increased prior to the radio flare, and the jet was screened from our view by hot gas until it broke out early last year.” IAC researcher Josefa Becerra adds that: “During the period 2022 to 2024, coinciding with the birth of the plasma jet, no significant change in visible light is observed. However, during the episode of activity in 2018 we observed important changes in the characteristics of its emission at these energies, corresponding to the appearance of clouds of ionised gas moving at high velocities and their subsequent disappearance. Ob- servations from Canary Island obser- vatories, in particular those made with the Gran Telescopio Canarias (GTC), located at the Roque de los Muchachos Observatory on La Palma, played a fundamental role in this finding.” A paper exploring that possibility, led by Laha, is under review at The Astrophysical Journal . Both Meyer and Megan Masterson, a doctoral candidate at the Massachusetts Insti- tute of Technology in Cambridge who also presented at the meeting, are co-authors. Using XMM-Newton observations, Masterson found that the black hole exhibited extremely rapid X-ray vari- ations between July 2022 and March 2024. During this period, the X-ray brightness repeatedly rose and fell by 10% every few minutes. Such changes, called millihertz qua- siperiodic oscillations, are difficult to detect around supermassive black holes and have been observed in only a handful of systems to date.