Original title: Search for intranight optical variability in a large sample of intermediate-mass black holes
Himanshu Sharma, Gopal-Krishna, Vibhore Negi, Hum Chand +2 · September 2026
Black holes can sit in the centers of galaxies and pull in matter. When they do, the area around them glows brightly. Scientists wanted to see if smaller monsters, called intermediate-mass black holes, change their brightness over just a few hours. To find out, researchers pulled sky survey data and tracked 62 of these objects over time. They measured the brightness of each target during single nights and compared it against steady nearby stars in the same images. If the target shifted brightness while the comparison stars stayed flat, it would show real flicker. They tested all the light measurements mathematically. In the end, they found no statistically significant quick flickers across any of their sessions.
Imagine you are watching a dim streetlamp at night, wondering if it flickers. Normally, you might glance at it once, but to be sure, you need to watch it steadily for hours and compare it to other lamps that you know are stable. In this paper, astronomers did something similar by monitoring galaxies over hours and comparing them to stable stars to detect light changes, but they found no flickering.
This result challenges earlier reports that suggested such galaxies flicker, affecting how astronomers understand black hole behavior. It helps refine models of how intermediate-mass black holes accrete matter and influence their host galaxies.
The study is limited to r-band optical data from the ZTF survey, with sessions of at least 2 hours. It does not cover other wavelengths or shorter timescales. The sample, though large for this type, may not be representative of all intermediate-mass black holes.
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Search for intranight optical variability in a large sample of intermediate-mass black holes — Himanshu Sharma, Gopal-Krishna, Vibhore Negi et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.