At the center of NGC 1275, an active supermassive black hole brightened in X-rays and was followed roughly 300 days later by a radio flare. The sequence may reveal how changes in matter falling toward a black hole connect to its jets—but the timing does not prove a direct cause, and the X-ray flare does not fit simple predictions for a black hole tearing apart a star.
What astronomers observed
NGC 1275 is the central galaxy of the Perseus Cluster, a galaxy cluster filled with hot gas. Its active galactic nucleus (AGN)—the bright, energetic region around its central black hole—has variable radio emission and launches jets that inflate large bubbles in the cluster’s hot gas.
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In a study accepted for publication in The Astrophysical Journal Letters, Sarah Ketchum and collaborators analyzed about 20 years of X-ray monitoring from NASA’s Neil Gehrels Swift Observatory. They modeled the observations to distinguish the AGN’s changing emission from the relatively constant X-ray glow of the surrounding intracluster medium. The typical reported errors on the X-ray flux were about 3%.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchThe team dated the start of an X-ray flare to 21 February 2023 (MJD 59956). The X-ray emission rose to about twice its usual level, with changes unfolding over days. Radio monitoring later recorded a flare at 43 GHz roughly 300 days after the X-ray flaring began. Those are observed signals and an approximate interval; they do not by themselves establish what connected the two events. Ketchum et al., “X-ray Flaring and Variability in NGC 1275”
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Why the radio flare may have come later
X-rays can trace activity close to a black hole, including changes in the hot material accreting onto it. Radio emission can trace energetic outflows, including jets. If a change in accretion is linked to a jet, the resulting radio brightening might not appear at the same time as the X-ray change.
One possible interpretation is that plasma launched near the black hole takes time to reach a bright knot or shock, where it interacts with surrounding gas or dust and produces detectable radio emission. The observations do not directly show plasma traveling from the black hole to such a location, so this remains a proposed explanation rather than a measured journey or travel time. The roughly 300-day interval is specific to this reported sequence, not a general delay that applies to black holes.
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Did the black hole tear apart a star?
A tidal disruption event (TDE) occurs when a star passes close enough to a black hole for its gravity to tear the star apart. Such events can produce a dramatic rise in emission, but the study says NGC 1275’s flare profile is inconsistent with simple TDE predictions. That qualification matters: the result is not a claim that every possible TDE model has been disproved.
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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesIn an interview with Space.com, Ketchum said, “We were able to rule out TDEs as a cause,” and described a spike in accretion as the likely explanation. The paper’s more specific framing is that the observed profile does not match simple TDE predictions. The reported radio flare is also better described as emission associated with outflowing material than as a black hole literally “burping” a swallowed star back out. Space.com’s report and interview with Ketchum
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the timing can—and cannot—tell us
The sequence is a potentially useful clue to the connection between accretion disks and jets: X-ray activity changed first, followed months later by radio activity. But the study does not establish that the first flare caused the second or determine precisely how the delay arose. Ketchum told Space.com that the X-ray observations sparsely sample changes in NGC 1275, making the exact relationship difficult to pin down, and said the interpretation should be tested with further observations.
The black hole’s mass is reported in the Space.com coverage as an estimate in the broad range of 100 million to 1 billion solar masses, based on the team’s inference—not as a precise measurement. The central result is therefore a particular, suggestive sequence in one galaxy, not a settled account of how all supermassive black holes feed or launch jets.
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