In just fractions of a second astronomers observed a black hole giving off ferocious red flashes, in one of the brightest black hole outbursts in recent years. The discovery was made in June 2015, when the black hole named V404 Cygni was consuming material that it had ripped from an orbiting companion star — the intense brightening continued for about two weeks.
V404 Cygni suffers from a stellar identity crisis. The “V” in its name designates it as a variable star (so it gets brighter and fainter). However, at least three times in the 20th century it has produced a bright outburst of energy; therefore it is also a nova. But it does not stop there; it is also known as a soft X-ray transient because it periodically emits short bursts of X-rays.
Armed with this knowledge, astronomers understand that V404 Cygni is a binary system that consists of a black hole and a “normal” companion star. However it also indicates that the black hole is robbing hot gas from its companion star.
V404 Cygni sits about 7,800 light years from Earth, and was the first definitive black hole to be identified in our galaxy. It can also appear extremely bright when it is actively devouring material.
Watch GeoBeats News video on the powerful burst observed by scientists:
The new study, published in the journal Monthly Notices of the Royal Astronomical Society, reported that the black hole had emitted impressive red flashes that lasted just fractions of a second, spewing out material that it could not swallow.
The international team of astronomers had associated the red colour with rapid jets of matter that had been expelled from close to the black hole. The team was led by the University of Southampton, and believes that the observations provide new insights into the construction of these jets and extreme black hole phenomena.
Lead author of the study, Dr. Poshak Gandhi an Associate Professor and STFC Ernest Rutherford Fellow in the University of Southampton’s Astronomy Group, said in a statement:
“The very high speed tells us that the region where this red light is being emitted must be very compact. Piecing together clues about the color, speed, and the power of these flashes, we conclude that this light is being emitted from the base of the black hole jet. The origin of these jets is still unknown, although strong magnetic fields are suspected to play a role.
“Furthermore, these red flashes were found to be strongest at the peak of the black hole’s feeding frenzy. We speculate that when the black hole was being rapidly force-fed by its companion orbiting star, it reacted violently by spewing out some of the material as a fast-moving jet. The duration of these flashing episodes could be related to the switching on and off of the jet, seen for the first time in detail.”
The observation was made by using the ULTRACAM fast imaging camera mounted on the William Herschel Telescope in La Palma on the Canary Islands.
Watch this video from NASA about the black hole named V404 Cygni:
The red flashes were extremely intense, being comparable to the output of about 1,000 suns. They were also extremely quick in duration (shorter than 1/40th of a second), “about ten times faster than the duration of a typical blink of an eye,” according to the Royal Astronomical Society.
Professor Vik Dhillon of the University of Sheffield and co-creator of ULTRACAM, said in a statement:
“ULTRACAM is unique in that it can operate at very high speed, capturing high frame-rate ‘movies’ of astronomical targets, in three colors simultaneously. This allowed us to ascertain the red color of these flashes of light from V404 Cygni.”
V404 Cygni last erupted in 1989 because bright black hole “outbursts” are so unpredictable in nature and are rare, astronomers have a very small window to react. Most upsurges have also been dimmer; however the 2015 event was extraordinarily bright providing an excellent opportunity to study.
Dr. Gandhi concluded:
“The 2015 event has greatly motivated astronomers to coordinate worldwide efforts to observe future outbursts. Their short durations, and strong emissions across the entire electromagnetic spectrum, require close communication, sharing of data, and collaborative efforts amongst astronomers.
“These observations can be a real challenge, especially when attempting simultaneous observations from ground-based telescopes and space satellites.”