Astronomers See Distant Eruption as Black Hole Destroys Star

Astronomers have, for the first time, captured the moment the gravity of a supermassive black hole ripped apart a star that drifted too close to causing a fast-moving jet of cosmic material and energy to be ejected.

Artist conception of a tidal disruption event (TDE) that happens when a star passes fatally close to a supermassive black hole, which reacts by launching a relativistic jet.

The event took place in a pair of colliding galaxies called Arp 299, nearly 150 million light-years from Earth. At the core of one of the galaxies, a black hole 20 million times more massive than the Sun shredded a star more than twice the Sun's mass, setting off a chain of events that revealed important details of the violent encounter.

The scientists tracked the event with multiple radio and infrared telescopes from across the world, including the Lovell Telescope at Jodrell Bank Observatory, working as part of the European Very Long Baseline Network (EVN).

Dr Rob Beswick, from the Jodrell Bank Centre for Astrophysics at The University of Manchester’s School of Physics and Astronomy, and co-investigator of this project, said: “This is a fantastic discover and an extremely important result in astronomy. It is a testament to the persistence of the science team and demonstrates the power of globally coordinated VLBI observations, including multiple telescopes from Jodrell Bank Observatory and the e-MERIN array in the UK.”

Artist conception of a tidal disruption event (TDE) that happens when a star passes fatally close to a supermassive black hole, which reacts by launching a relativistic jet. It zooms out of the central region of its host galaxy, Arp299B, which is undergoing a merging process with Arp299A (the galaxy to the left).

Artist conception of a tidal disruption event (TDE) that happens when a star passes fatally close to a supermassive black hole, which reacts by launching a relativistic jet. It zooms out of the central region of its host galaxy, Arp299B, which is undergoing  a merging process with Arp299A (the galaxy to the left).

Image credit: Sophia Dagnello, NRAO/AUI/NSF; NASA, STScI

"Never before have we been able to directly observe the formation and evolution of a jet from one of these events," said Miguel Perez-Torres, of the Astrophysical Institute of Andalucia in Granada, Spain. "Tidal disruption events can provide us with a unique opportunity to advance our understanding of the formation and evolution of jets in the vicinities of these powerful objects," he added.

Dr Rob Beswick, from the Jodrell Bank Centre for Astrophysics at The University of Manchester’s School of Physics and Astronomy, and co-investigator of this project, said: “This is a fantastic discovery and an extremely important result in astronomy. It is a testament to the persistence of the science team and demonstrates the power of globally coordinated VLBI observations, including multiple telescopes from Jodrell Bank Observatory and the e-MERLIN array in the UK.”

Dr Beswick, who is also Head of Science Operations and Support of UK’s e-MERLIN/VLBI National Facility, added: “The discovery came as a surprise. The initial infrared burst was discovered as part of a project that sought to detect supernova explosions in such colliding pairs of galaxies. Arp 299 has seen numerous stellar explosions, and has been dubbed a ‘supernova factory.’ This new object originally was considered to be a supernova explosion.”

Tidal disruption Events may have been more common in the distant Universe, so studying them may help scientists understand the environment in which galaxies developed billions of years ago. The discovery of this event embedded in a dust obscured galaxy, and not seen in visible or X-ray light, may mean it is just the tip of the iceberg of an until now hidden population. Seppo Mattila, of the University of Turku in Finland added that “By looking for these events with infrared and radio telescopes, we may be able to discover many more, and learn from them."

The discovery has taken over a decade to unravel. The first indication came on January 30, 2005, when astronomers using the William Herschel Telescope in the Canary Islands discovered a bright burst of infrared emission coming from the nucleus of one of the colliding galaxies in Arp 299. On July 17, 2005, the National Science Foundation’s Very Long Baseline Array (VLBA) revealed a new, distinct source of radio emission from the same location.

Animated gif showing the first light at radio wavelengths of the TDE in Arp299B (=Arp299B-AT1) back in 2005, and following the jet formation and evolution with time for more than 10 years.

Animated gif showing the first light at radio wavelengths of the TDE in Arp299B (=Arp299B-AT1) back in 2005, and following the jet formation and evolution with time for more than 10 years. The movie plays side by side, showing images at 5.0 GHz (left) and 8.4 GHz (right) obtained with a world array of  radio telescopes, including the powerful European VLBI Network (EVN) and the Very Long Baseline Array (VLBA) of the NRAO.

Image credit: Bill Saxton, NRAO/AUI/NSF

The researchers then used the Nordic Optical Telescope on the Canary Islands and NASA's Spitzer space telescope to follow the object's infrared emission. Continued observations with the EVN, VLBA and other radio telescopes, carried out over nearly a decade, showed the source of radio emission expanding in one direction at an average of one-quarter the speed of light, just as expected for a jet.  

Only in 2011, six years after discovery, the radio-emitting portion began to show an elongation. Subsequent monitoring showed the expansion growing, confirming that what the scientists are seeing is a jet, not a supernova.

These observations used multiple radio-telescope antennas, separated by thousands of miles, to gain the resolving power, or ability to see fine detail, required to detect the expansion of an object so distant. "A global network of collaborating radio antennas is the only way to see this jet structure and study the evolution of such distant objects in detail." says Eskil Varenius, formerly at Onsala Space Observatory in Sweden, now at Jodrell Bank Centre for Astrophysics in the UK. "It is incredible what these telescope networks can do. This is a clear case where international collaboration achieve a combined whole much greater than the sum of its parts."

The finding of this work are published in the journal Science (https://doi.org/10.1126/science.aao4669)


Associated Press releases

https://public.nrao.edu/news/black-hole-destroys-star
http://www.jive.eu/surprise-discovery-provides-new-insights-stellar-deaths

The UK’s e-MERLIN/VLBI National Radio Astronomy Facility

e-MERLIN is the UK's National Radio Astronomy Facility and is operated by the University of Manchester on behalf of the UK's Science and Technology Facility (STFC). e-MERLIN is an array of seven radio telescopes across the UK, connected to a powerful central correlator at Jodrell Bank Observatory (JBO), The University of Manchester. It is operated both as a dedicated radio interferometer producing high-resolution radio images and also provides the UK contribution to the European VLBI Network (EVN), which links telescopes across Europe and China for observations at milliarcsecond resolution.

The e-MERLIN/VLBI National Facility is owned and operated by The University of Manchester on behalf of the UK’s Science and Technology Facilities Council.

Jodrell Bank Centre for Astrophysics  - www.jodrellbank.manchester.ac.uk

e-MERLIN/VLBI National Facility - www.e-merlin.ac.uk

Science and Technology Facilities Council - www.stfc.ukri.org

European VLBI Network telescopes used in this project

In total nineteen different EVN telescopes involved in the observation as part of this project, including: Effelsberg Radio Telescope (Max-Planck Institute for Radio Astronomy, Germany), e-MERLIN/Jodrell Bank Observatory, Lovell, Mk2 and Cambridge telescopes (University of Manchester, UK), Medicina Radio Observatory (National Institute for Astrophysics, Italy), Onsala Space Observatory (Chalmers University of Technology, Sweden), Noto Radioastronomical Station (National Institute for Astrophysics, Italy), Torun„ Centre for Astronomy (Nicolaus Copernicus University, Poland), Westerbork Synthesis Radio Telescope (ASTRON, the Netherlands),  Yebes Observatory (National Geographic Institute, Spain),  Shanghai Astronomical Observatory, Yunnan Observatory and Xinjiang Astronomical Observatory (Chinese Academy of Sciences, China), Ventspils Telescope (International Radio Astronomy Centre, Latvia), Wettzell Telescope (Geodetic Observatory Wettzell, Germany), Robledo Telescope (NASA-Deep Space Network, Madrid, Spain),  Svetloe Radio Astronomical Observatory, Badary Radio Astronomical Observatory and the Zelenchukskaya (Radioastronomical Observatory (Institute of Applied Astronomy (IAA) Russia).

Very Long Baseline Array – Long Baseline Observatory

The Long Baseline Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

National Radio Astronomy Observatory - www.nrao.edu

More about e-MERLIN, VLBI, the European VLBI Network and JIVE

e-MERLIN and VLBI are radio interferometers which use multiple large radio telescopes distributed over great distances to observe the same region of sky simultaneously. Data from each telescope is sent to a central "correlator" to produce images with higher resolution than the most powerful optical telescopes.

The e-MERLIN national facility (www.e-merlin.ac.uk) is an interferometric array of 7 large telescopes (including the 76-m Lovell Telescope) spanning the southern half of the UK which are remotely connected to a central facility at Jodrell Bank Observatory via a dedicated high speed fibre network. With a maximum baseline length of 220 km, e-MERLIN provides a unique capability for microJansky sensitivity radio imaging, spectroscopy, polarisation and astrometry at 0.01-0.15-arcsec resolution in broad frequency bands. The e-MERLIN/VLBI National Facility provides the UK contribution to the European VLBI Network. The e-MERLIN National facility is operated by the University of Manchester on behalf of the UK’s Science and Technology Facility Council (STFC; www.stfc.ac.uk)

The European VLBI Network (EVN; www.evlbi.org) is an interferometric array of radio telescopes spread throughout Europe, Asia, South Africa and the Americas that conducts unique, high-resolution, radio astronomical observations of cosmic radio sources. Established in 1980, the EVN has grown into the most sensitive VLBI array in the world, including over 20 individual telescopes, among them some of the world's largest and most sensitive radio telescopes. The EVN is administered by the European Consortium for VLBI, which includes a total of 15 institutes, including the Joint Institute for VLBI ERIC (JIVE).

The Joint Institute for VLBI ERIC (JIVE; www.jive.eu) has as its primary mission to operate and develop the EVN data processor, a powerful supercomputer that combines the signals from radio telescopes located across the planet. Founded in 1993, JIVE is since 2015 a European Research Infrastructure Consortium (ERIC) with six member countries: France, Latvia, the Netherlands, United Kingdom, Spain and Sweden; additional support is received from partner institutes in China, Germany, Italy and South Africa.


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