Intense Wind Felt Around V404 Cygni, The Black Hole Closest to Earth

A team of international astrophysicists, including Professor Phil Charles from the University of Southampton, have identified an intense wind from one of the known black holes nearest to the Earth.

During observations of V404 Cygni, which went into a bright and violent outburst in June 2015 after more than 25 years of quiescence, the team started to take optical measurements of the black hole's accretion disc with the use of the 10.4m Gran Telescopio CANARIA (GTC). This telescope has been known to be the biggest optical-infrared telescope in the world, and can be found at the the Roque de los Muchachos Observatory (Garafía, La Palma) in the Canary Islands.

The results revealed presence of a wind of neutral material, unionised hydrogen and helium, which is formed in the outer layer of the disc and is known to be responsible for regulating the accretion of material by the black hole. The wind that was detected for the first time in a system of this type, has a very high velocity at 3,000 kilometers per second so that it can escape from the gravitational field around the black hole, Science Daily reported.

At the end of the outburst, the GTC observations showed the presence of nebula formed from material spewed out by the wind. This phenomenon has been observed for the first time in a black hole, also allows scientists project the quantity of mass emitted into the interstellar medium. Phys.org mentioned that Professor Charles, from Physics and Astronomy at the University of Southampton said, "Its presence allows us to explain why the outburst, in spite of being bright and very violent, with continuous changes in luminosity and ejections of mass in the form of jets, was also very brief, lasting only two weeks."

Teo Muñoz Darias, a researcher at the Instituto de Astrofísica de Canarias (IAC) and the lead author of the study (and also a former Marie Curie Fellow at Southampton), also said that the brightness of the source and the large collecting area of the telescope allowed them to detect the wind and to measure the different varieties of its properties on time-scales of minutes. He also added saying, "The database obtained is probably the best ever observed for an object of this kind. This outburst of V404 Cygni, because of its complexity and because of the high quantity and quality of the observations, will help us understand how black holes swallow material via their accretion discs."

V404 Cygni, at only 8,000 light years away, is one of the closest known black holes to the Earth, and has a particularly large accretion disc (with a radius of about ten million kilometres), making its outbursts especially bright at all wavelengths (X-rays, visible, infrared and radio waves).