London: An international team of astrophysicists has detected an intense wind from one of the closest known black holes to the Earth.
The team led by professor Phil Charles from the University of Southampton observed “V404 Cygni” which went into a bright and violent outburst in June 2015 after more than 25 years of quiescence.
They began taking optical measurements of the black hole’s accretion disc using the Gran Telescopio CANARIAS (GTC) – the biggest optical-infrared telescope in the world in the Canary Islands.
The results show the presence of a wind of neutral material (unionised hydrogen and helium), which is formed in the outer layers of the accretion disc, regulating the accretion of material by the black hole.
This wind, detected for the first time in a system of this type, has a very high velocity (3,000 kms per second) so that it can escape from the gravitational field around the black hole.
“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,” explained professor Charles.
“V404 Cygni” is a black hole within a binary system located in the constellation of Cygnus. At only 8,000 light years away, it is one of the closest known black holes to the Earth and has a particularly large accretion disc (with a radius of about 10 million kms), making its outbursts especially bright at all wavelengths (X-rays, visible, infrared and radio waves).
The observations also revealed the presence of a nebula formed from material expelled by the wind.
This phenomenon, which has been observed for the first time in a black hole, also allows scientists to estimate the quantity of mass ejected into the interstellar medium.
“This outburst of ‘V404 Cygni’ will help us understand how black holes swallow material via their accretion discs,” noted Teo Muñoz Darias, researcher at the Instituto de AstrofÃsica de Canarias (IAC) in a paper published in the journal Nature.
