caught in an explosive phase where the black hole's powerful feedback is actively blasting away the material surrounding it
In the depths of cosmic time, where galaxies were still learning their shapes, supermassive black holes were quietly—and violently—rewriting the rules of their own existence. A team of astronomers led by Matthew Stepney has discovered 77 previously hidden quasars, more than doubling the known population of dust-shrouded cosmic engines and illuminating a fleeting but formative moment in the universe's early biography. These objects, detected through infrared light by NASA's SPHEREx telescope, appear to represent galaxies caught mid-transformation—their central black holes blasting away the very dust that once concealed them. In finding them, science gains its first substantial window into how the universe's largest structures were forged in fire and obscured light.
- For decades, a critical chapter in galaxy evolution has remained nearly invisible—hidden behind walls of cosmic dust that swallow the light of some of the universe's most powerful objects.
- The discovery of 77 new heavily reddened quasars more than doubles the known sample overnight, including seven of the oldest ever found, originating within the universe's first 2.1 billion years.
- These are not ordinary quasars—they occupy a rare middle ground between deeply buried objects and cleared blue quasars, suggesting they are caught in an explosive transitional phase where black hole feedback is actively winning against its own surroundings.
- An unexpected excess of ultraviolet radiation in roughly three-quarters of the sample hints at simultaneous star formation, painting a picture of galaxies in violent, creative upheaval.
- Future surveys promise to expand this sample further, potentially rewriting foundational models of how supermassive black holes shaped the early universe and the galaxies we inhabit today.
At the center of most large galaxies lives a supermassive black hole, and when it feeds voraciously on surrounding material, it becomes a quasar—one of the brightest phenomena the universe produces. Some of these engines, however, hide behind thick veils of dust, their light dimmed before it reaches Earth. For decades, fewer than fifty such obscured quasars had been confirmed, leaving enormous gaps in our understanding of how black holes shape their host galaxies. Now, a team led by Matthew Stepney at Chile's Center of Excellence in Astrophysics and Related Technologies has more than doubled that count, discovering 77 new examples using infrared data from NASA's SPHEREx telescope.
These hidden quasars appear to mark a specific evolutionary moment—when two galaxies collide and merge, sending gas rushing toward the combined system's center. The result is simultaneous star formation and rapid black hole feeding, all wrapped in a thick blanket of dust that renders the objects nearly invisible to conventional telescopes. The newly discovered sample spans a period when the universe was between 1.6 and 4.3 billion years old, with seven objects ranking among the earliest heavily reddened quasars ever detected.
What distinguishes these quasars is their peculiar position in a spectrum of obscuration. Unlike deeply buried objects dominated by hot dust, or cleared blue quasars where dust has already been swept away, these reddened quasars show surprisingly little hot dust despite being among the most intrinsically luminous objects known. This scarcity suggests they are caught mid-explosion—their black holes actively blasting surrounding material outward in a brief but transformative feedback phase. In roughly three-quarters of the sample, an unexpected excess of ultraviolet light points to vigorous star formation occurring simultaneously in the host galaxy.
The broader significance lies in what this sample makes possible for the first time: a real observational foundation for studying how supermassive black holes interacted with their surroundings during the universe's formative era. Future surveys are expected to expand the sample considerably, potentially reshaping how science understands the violent, generative processes that gave the cosmos its present form.
At the heart of most large galaxies sits a supermassive black hole. When one of these objects begins feeding voraciously on surrounding material, it becomes a quasar—one of the brightest phenomena in the universe. But some of these cosmic engines hide behind thick veils of dust, their light dimmed and scattered before it reaches Earth. For decades, astronomers have struggled to find and study these obscured objects. Now, a team led by Matthew Stepney at Chile's Center of Excellence in Astrophysics and Related Technologies has more than doubled the known population of heavily dust-shrouded quasars, discovering 77 new examples and opening a window into a violent and brief chapter in how galaxies grow.
The discovery matters because these hidden quasars appear to represent a specific evolutionary moment—a phase that occurs when two galaxies collide and merge. During this collision, gas streams toward the center of the newly combined system, triggering two simultaneous processes: intense bursts of star formation and the rapid feeding of the central black hole. The dust generated in this cosmic violence creates a thick blanket that absorbs visible light, making these objects nearly invisible to conventional optical telescopes. Until now, astronomers had confirmed only about fifty such dust-obscured quasars, leaving major gaps in their understanding of how supermassive black holes shape their host galaxies during these critical moments.
Stepney's team used infrared data and spectrophotometric techniques from NASA's SPHEREx telescope to identify their 77 new quasars. The sample spans a crucial period in cosmic history, when the universe was between 1.6 and 4.3 billion years old. Most remarkably, seven of these newly discovered objects rank among the earliest heavily reddened quasars ever found, originating from the universe's first 2.1 billion years after the Big Bang. These ancient examples provide astronomers with their first substantial observational evidence of how supermassive black holes grew during the universe's infancy.
What makes these quasars distinct is their intermediate position in a spectrum of obscuration. Blue quasars represent systems where surrounding dust has already been cleared away, leaving only a bright infrared-emitting torus of material around the black hole. Galaxies heavily obscured by hot dust represent the opposite extreme—deeply buried objects where dust dominates the observed radiation. The newly discovered heavily reddened quasars occupy the middle ground. They are intrinsically among the brightest objects known, yet they show surprisingly little hot dust compared even to the clearer blue quasars. This peculiar combination suggests they occupy a distinct evolutionary stage.
The scarcity of hot dust points to something remarkable: these quasars may be caught in an explosive phase where the black hole's powerful feedback is actively blasting away the material surrounding it. When astronomers correct for the dimming effect of dust, these objects reveal themselves as extraordinarily luminous—some of the most energetic phenomena in the observable universe. In roughly three-quarters of the sample, the team also detected an unexpected excess of ultraviolet radiation, likely produced by both scattered quasar light and vigorous star formation in the host galaxy itself.
This picture aligns with a leading theory of galaxy evolution: supermassive black holes undergo a brief but violent phase marked by reddening and dust obscuration, typically triggered by galactic mergers. During this stage, the black hole's radiation-driven winds act as an extreme feedback mechanism, ultimately clearing the central regions of their galaxies. The heavily reddened quasars appear to capture galaxies at the moment when this feedback begins to win—when the black hole's outflows start to overcome the inflow of material and begin reshaping the galaxy's structure.
The implications extend beyond understanding individual objects. These 77 quasars provide the first substantial sample for studying how supermassive black holes interact with their surroundings and influence the early universe's development. They fill a critical gap in the observational foundation for black hole formation theory. Future surveys promise to expand the sample considerably, potentially revealing even more about the diversity of these hidden monsters and their role in sculpting the cosmos during its formative billions of years.
Notable Quotes
These objects represent a phase evolutive distinct, both in composition and in brightness— Research findings on heavily reddened quasars
The Hearth Conversation Another angle on the story
Why does it matter that we find these quasars now, after decades of knowing they should exist?
Because without a real sample, you're building theory on almost nothing. Fifty confirmed objects isn't enough to test whether your ideas about how galaxies evolve actually hold up. Seventy-seven more changes the conversation from speculation to evidence.
These quasars are hidden by dust. Why not just look harder with better telescopes?
Visible light gets absorbed by dust. You need infrared—light with longer wavelengths that can pass through. SPHEREx was designed to see exactly this kind of thing. It's not about looking harder; it's about looking in the right part of the spectrum.
You mentioned they're caught in an explosive phase. What does that actually mean physically?
The black hole is feeding so intensely that its radiation creates powerful winds that blast outward. These winds are clearing away the dust and gas that surrounds the black hole. It's violent, temporary, and it fundamentally changes the galaxy's structure. Once the material is blown away, the galaxy enters a different phase entirely.
So these are galaxies in the middle of a transformation?
Exactly. You have blue quasars where the dust is already gone, and heavily obscured galaxies where the dust is still thick. These newly discovered ones are caught between those states—the black hole is actively winning the fight against its surroundings.
Why are the earliest ones—from the first 2.1 billion years—particularly significant?
Because they show that supermassive black holes were already massive and active when the universe was very young. That's a puzzle astronomers are still working to solve. How did they grow so large so fast? These ancient examples give us real data to work with.
What happens next in the research?
More observations, larger samples, better understanding of the diversity within this population. Each new quasar is another data point about how black holes and galaxies co-evolve. The goal is to move from having a few examples to having a real census.