Brewing, Raging and Lulling: a quasar storm caught in action
TALES members Antonis Georgakakis and Maria Chira co-author a new research publication presenting the rare, complete lifecycle of a cosmic storm ‒ from breakout to calming down ‒ in a distant quasar, a supermassive black hole actively devouring matter. By tracking the variations of the X-ray light emitted by the quasar over a period of two decades, researchers revealed a powerful wind of dense gas erupting from the black hole’s violent immediate environment. This gas temporarily blocked our view of the quasar before finally dispersing. Remarkably, at its heyday this wind was strong enough to heat up gaseous matter far beyond the black hole’s sphere of influence. The observed transfer of energy from the black hole’s immediate environment to the inner part of the galaxy, has long been theorised by astronomers as an important process for understanding galaxy formation and evolution.
Most massive galaxies in the universe, including our own Milky Way, host at their centres black holes that weigh millions or even billions of times the mass of our Sun. The strong gravitational pull of these beasts captures matter, mostly gas, making it spiral inward and eventually fall in them, growing their masses even more.
Matter however, does not just disappear quietly. The intense gravity and friction heat it up to incredible temperatures, generating huge amounts of energy that is radiated away into space as brilliant light. It is this light that our telescopes can see. When a supermassive black hole is actively feeding and generating this powerful light show, we call it a quasar.
Researchers at the National Observatory of Athens were studying the X-ray light of a sample of quasars when they discovered that one of them, designated 2MASS J14302580+4159572, behaved strangely. Its X-ray light showed unexpectedly extreme intensity variations over a period of about twenty years.
The X-ray light intensity variations of 2MASS J14302580+4159572 are caused by dense warm material—in the form of gaseous clouds—moving in front of the source. This material blocks our view of the quasar and partially absorbs the X-ray light it produces.
While such “obscuring” events are not uncommon, there is something unique about 2MASS J14302580+4159572: following the “obscured” phase lasting for about 17 years, the clouds began to disperse allowing the light of the quasar to shine through once again and its X-ray intensity to recover.
Figure Caption: Watching a cloud of gas drift across our view of a distant quasar: The top illustration shows how the amount of gas between us and the quasar 2MASS J14302580+4159572 has changed over more than twenty years. Each data point (circles with error bars) shows the measured gas density along the line of sight at a given observation date. When the quasar was first observed in 2002, this value was close to zero — almost no absorbing gas stood between us and the quasar. By 2005, however, the density had jumped sharply, and it stayed high and roughly constant for the next 17 years. Then, in X-ray observations taken between 2022 and 2024, the density dropped again, signaling that the obscuring gas was clearing away. The bottom illustration shows what these changes mean physically. Left: in the early stage, the quasar’s wind is just beginning to form and has not yet reached our line of sight. Middle: During the obscured phase, the wind has fully developed and moves across our line of sight, absorbing part of the quasar’s X‑ray emission — matching the high gas density seen in the top panel between 2005 and 2022. Right: In the final recovery stage, the wind weakens and disperses, allowing the gas density along our line of sight to fall again, as seen in the most recent observations (2022-2024). In each panel, the orange/brown structure represents the quasar, i.e. the disk of matter spiraling to the central black hole, the black arrow tipped with an X-ray telescope marks our line of sight, and the diffuse cyan region represents a wind of dense gas blowing outward from the disk.
