Researchers from Kyoto University have detected visible light coming from a black hole for the first time and report that a 20 cm telescope is all you need to do so. The team observed the phenomena by taking note of the visible light during outbursts, which is indicated by the flickering light from the black hole's gaseous outer proximity. The findings imply that in addition to x-rays, optical rays can also be used to provide reliable observational data for the acitivity of active black holes.
"We now know that we can make observations based on optical rays - visible light, in other words - and that black holes can be observed without high-spec x-ray or gamma-ray telescopes," said Mariko Kimura, lead author of the study, in a press release.
Every several decades, black holes undergo "outbursts" that emit enormous amounts of energy, such as x-rays, that stem from substances that fall into the black hole. Accretion disks, which are made up of spiral gas patterns stemming from a companion star, generate x-rays in their inner portions and are the standard measurement observed in order to give scientists a better idea of the black hole's activity.
V404 Cygni, a black hole binary believed to be the closest to Earth, woke up from its 26-year dormancy June 15, 2015 and underwent an outburst of light. The study in question obtained data from this black hole through the detection of repetitive patterns of optical fluctuations, which the team discovered were correlated with those of x-rays.
"Stars can only be observed after dark, and there are only so many hours each night, but by making observations from different locations around the globe, we're able to take more comprehensive data," said Daisaku Nogami, co-author of the study. "We're very pleased that our international observation network was able to come together to document this rare event."
The findings were published in the Jan. 6 issue of Nature.
