Sept. 5 (UPI) -- Astronomers have established a link between the brightness of material consumed by a black hole and the rate at which the material is being accreted.
Active black holes are characterized by emissions variability.
"The light emitted by the material that is falling -- its brightness -- changes a lot over time, without a stable pattern," Paula Sánchez-Sáez, a doctoral student in the astronomy department at the University of Chile, said in a news release.
To better understand this variability, Sánchez-Sáez and her research partners analyzed the relationship between the amplitude of brightness variability and an active galactic nuclei's average luminosity and accretion rate, as well as the mass of nuclei's supermassive black hole.
The analysis revealed only one predictive relationship -- a link between variability and the accretion rate.
"[The accretion rate] is nothing but how much material is falling into this supermassive black hole," said University of Chile astronomer Paulina Lira.
How much or how little a black hole is swallowing impacts the variability of the active galactic nuclei's brightness.
"And what we detect is that the less they swallow, the more they vary," Lira said.
Until recently, it was difficult to measure an active galactic nuclei's accretion rate with sufficient accuracy. But advances in technology allowed astronomers to measure the accretion rate of more than 2,000 objects.
Astronomers hope followup analysis of the newly discovered relationship will help scientists identify the physical mechanism behind brightness variability.
"Another very important property is the time scale of variability of these objects," Sánchez-Sáez said. "To measure this property accurately we need to have light curves with a coverage of more than 10 years. So we must wait until future surveys."