16 March 2016 Contact Information Appears Below The full text of this press release, images and video is available at: http://www.southampton.ac.uk/weareconnected ASTRONOMERS SEE BLACK HOLE RAGING RED Violent red flashes, lasting just fractions of a second, have been observed during one of the brightest black hole outbursts in recent years. In June 2015, a black hole called V404 Cygni underwent dramatic brightening for about two weeks, as it devoured material that it had stripped off an orbiting companion star. V404 Cygni, which is about 7,800 light years from Earth, was the first definitive black hole to be identified in our Galaxy and can appear extremely bright when it is actively devouring material. In a new study, published in the journal Monthly Notices of the Royal Astronomical Society, an international team of astronomers, led by the University of Southampton, report that the black hole emitted dazzling red flashes lasting just fractions of a second, as it blasted out material that it could not swallow. The astronomers associated the red colour with fast-moving jets of matter that were ejected from close to the black hole. These observations provide new insights into the formation of such jets and extreme black hole phenomena. Lead author of the study Dr Poshak Gandhi, Associate Professor and STFC Ernest Rutherford Fellow in the University of Southampton’s Astronomy Group, comments: “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 colour, 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.” Due to the unpredictable nature and rarity of these bright black hole ‘outbursts’, astronomers have very little time to react. For example, V404 Cygni last erupted back in 1989. V404 Cygni was exceptionally bright in June 2015 and provided an excellent opportunity for such work. In fact, this was one of the brightest black hole outbursts in recent years. But most outbursts are far dimmer, making them difficult to study. Each flash was blindingly intense, equivalent to the power output of about 1,000 suns. And some of the flashes were shorter than 1/40th of a second — about ten times faster than the duration of a typical blink of an eye. Such observations require novel technology, so astronomers used the ULTRACAM fast imaging camera mounted on the William Herschel Telescope in La Palma, on the Canary Islands. Professor Vik Dhillon, of the University of Sheffield and co-creator of ULTRACAM, said: “ULTRACAM is unique in that it can operate at very high speed, capturing high frame-rate ‘movies’ of astronomical targets, in three colours simultaneously. This allowed us to ascertain the red colour of these flashes of light from V404 Cygni.” 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.” This research was a collaboration between the universities of Southampton, Sheffield and Warwick, together with international partners in Europe, USA, India and the UAE. The research was supported by the Science and Technology Facilities Council, the UK- India UKIERI-UGC Thematic Partnerships, the Royal Society, the Spanish Ministry of Economy and Competitiveness (MINECO), CONACyT (Mexico), and Spanish Ministerio de Educacion, Cultura y Deporte, a Marie Curie FP7-Reintegration-Grant and the University of Southampton. ### Notes for editors: 1. The attached image shows an artist's impression of a black hole, similar to V404 Cyg, devouring material from an orbiting companion star. Credit: ESO/L. Calçada. 2. A copy of the paper ‘Furiously Fast and Red: Sub-second Optical Flaring in V404 Cyg during the 2015 Outburst Peak’ Monthly Notices of the Royal Astronomical Society MN- 15-4100-MJ.R2 is available from Media Relations on request. 3. The William Herschel Telescope (WHT) is a 4.20-metre (165 in) optical/near-infrared reflecting telescope located at the Observatorio del Roque de los Muchachos on the island of La Palma in the Canary Islands, Spain. The telescope, which is named after William Herschel, is part of the Isaac Newton Group of Telescopes. It is funded by research councils from the United Kingdom, the Netherlands and Spain. 4. ULTRACAM was developed by Professor Vik Dhillon of the University of Sheffield together with Professor Tom Marsh of the University of Warwick. It is supported by Science and Technology Facilities Council funding. 5. Through world-leading research and enterprise activities, the University of Southampton connects with businesses to create real-world solutions to global issues. Through its educational offering, it works with partners around the world to offer relevant, flexible education, which trains students for jobs not even thought of. This connectivity is what sets Southampton apart from the rest; we make connections and change the world. http://www.southampton.ac.uk/ http://www.southampton.ac.uk/weareconnected #weareconnected ### Contacts: Glenn Harris Media Relations, University of Southampton, Tel 023 8059 3212, Email: G.Harris@soton.ac.uk, Twitter: @glennh75 @poshakgandhi www.soton.ac.uk/mediacentre/ Follow us on twitter: http://twitter.com/unisouthampton Like us on Facebook: www.facebook.com/unisouthampton ------------------------------------------------------------------------ If you do not wish to receive press releases or other announcements that are forwarded to the news media by the American Astronomical Society, please unsubscribe by replying accordingly to any incoming email, or send email to larry.marschall+AEA-aas.org. Requests for referrals to experts on astronomy and space science should be sent to the same address. 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