AsianScientist (Jan. 13, 2016) – A research team from Japan has found that the activity of black holes can in fact be observed by visible light emitted from surrounding gases during ‘outbursts’ of energy.
This indicates that optical rays, not just X-rays, provide reliable observational data for black hole activity—and therefore, anyone with a 20cm home-use telescope can view this phenomena. The article was published in Nature.
“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,” explains lead author Ms. Kimura Mariko, a masters student at Kyoto University.
Once in several decades, some black hole binaries undergo outbursts, in which enormous amounts of energy—including X-rays—are emitted from substances that fall into the black hole. Black holes are commonly surrounded by an accretion disk, in which gas from a companion star is slowly drawn to the hole in a spiral pattern. Activities of black holes are typically observed through X-rays generated from the inner portions of these accretion disks, where temperatures reach ten million degrees Kelvin or more.
V404 Cygni, one of the black hole binaries thought to be nearest to Earth, ‘woke up’ after 26 years of dormancy on 15 June 2015 as it underwent such an outburst. Led by astronomers from Kyoto University, an international team together with collaborators at Japan’s national space agency JAXA, national laboratory RIKEN and Hiroshima University succeeded in obtaining unprecedented amounts of data from V404 Cygni.
Based on their analyses, optical fluctuation patterns, or flickering lights that the team observed, correlated with those of X-rays. This light originated from the X-rays emerging from the innermost region of the accretion disk around the black hole. These X-rays irradiate and heat the outer region of the disk, making it emit optical rays—thus becoming visible to the human eye.
The outburst observation, the researchers say, was the fruit of international collaboration across countries in different time zones.
“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,” says co-author Assistant Professor Daisaku Nogami.
“We’re very pleased that our international observation network was able to come together to document this rare event.”
The article can be found at: Kimura et al. (2016) Repetitive Patterns in Rapid Optical Variations in the Nearby Black-Hole Binary V404 Cygni.
———
Source: Kyoto University; Photo: NASA Goddard Space Flight Center/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.