A cosmic mystery may finally have a new answer: astronomers led by Arizona State University and the Raman Research Institute have found evidence that narrow jets from supermassive black holes can reach far beyond their galaxies and help decide whether those galaxies continue creating stars.
The result addresses a long-standing puzzle. Large galaxies are surrounded by enormous reservoirs of gas known as the circumgalactic medium, or CGM. In principle, that gas should cool, fall inward and provide material for new generations of stars. Yet many massive galaxies eventually become quiet even though the raw material for star formation still surrounds them.
The new study, published in Astrophysical Journal Letters, suggests that jets launched by actively feeding supermassive black holes can heat, ionize and disturb this surrounding gas over extraordinary distances. In effect, a region roughly comparable in scale to our solar system can influence material spread across hundreds of thousands of light-years.
The team, led by Sanchayeeta Borthakur of Arizona State University and Namrata Roy of the Raman Research Institute, combined optical observations from the Dark Energy Spectroscopic Instrument with radio measurements from the LOFAR Two-metre Sky Survey. Instead of averaging the gas around galaxies in every direction, they examined the regions aligned with the radio jets.
That directional approach revealed the hidden signal. Hydrogen gas in the CGM glowed more strongly along the paths of the jets, producing a distinct H-alpha signature. The effect was especially clear near the regions where the jets first encounter the surrounding medium and farther out where large amounts of energy appear to be deposited.
This provides direct observational evidence for a mechanism astronomers have long suspected. By keeping circumgalactic gas hot and turbulent, black-hole jets can prevent it from cooling efficiently and falling back toward the galaxy. Without that inflow, the galaxy loses access to the fuel required for sustained star formation.
The scale of the connection is what makes the result so striking. A supermassive black hole may occupy an extremely small central region relative to its host galaxy, yet the energy released near it can regulate the future of a system containing hundreds of billions of stars.
The finding also gives a physical dimension to an old astronomical paradox: black holes are commonly associated with destruction, but their role in cosmic evolution is more subtle. They do not simply consume matter. Through jets and radiation, they can regulate when and where stars form, changing the architecture of galaxies across billions of years.
That makes the discovery existential as well as technical. Stars create the heavy elements needed for rocky planets and biology. A process beginning near a black hole can therefore influence how much future stellar material a galaxy produces — and, indirectly, the environments in which planets and life might eventually emerge.
The researchers caution that black-hole feedback is complex. Not all active galaxies produce the same jets, gas can exist in multiple phases, and the study relies on stacking many weak signals to reveal a statistical pattern. The cool-gas tracer magnesium, for example, appeared much more evenly distributed and did not show the same directional relationship.
Still, the observations offer some of the clearest evidence yet that black-hole jets leave a measurable imprint on the gaseous halos around galaxies. The work complements recent research on the early Universe, including MEGATRON simulations of the first stars and cosmic elements, by showing how the later evolution of galaxies can be regulated by the extreme objects growing at their centers.
In the largest sense, the study reframes a black hole from a passive endpoint of stellar death into an active architect of cosmic history — a compact object capable of influencing whether an entire galaxy remains fertile with new stars or slowly falls silent.
References
https://news.asu.edu/b/20260924-black-hole-jets-may-shape-fate-entire-galaxies
https://doi.org/10.3847/2041-8213/ae1f2e
https://www.nature.com/articles/d41586-026-03036-9