Some distant black holes are flickering so fast that light doesn't even have time to travel across them.
March 26, 2026
Original Paper
The shortest detected intra-day variability of active galactic nuclei in TESS survey
arXiv · 2603.23752
The Takeaway
Using the TESS space telescope, researchers found that many black holes vary in brightness on timescales that are physically too fast given their massive size. It is like seeing a city-sized neon sign blink on and off faster than a signal can travel from one end of the city to the other, suggesting our current maps of black hole 'feeding zones' are fundamentally wrong.
From the abstract
AGNs are known to be variable in almost all wavelengths and timescales. The shortest variability timescale of AGNs can be used to probe the smallest scale structures within AGNs. We aim to measure the shortest detected variability timescale, $t_{min,ul}$, of type 1 radio-quiet Seyfert galaxies and analyse their characteristics. We extracted TESS light curves of 47 Seyfert 1 galaxies. We measured the PSDs of the sample, modelled by a power law model plus a constant noise, and constrained the shor