From Julius-Maximilians-Universität Würzburg: “Spinning Black Hole Powers Jet by Magnetic Flux”

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From Julius-Maximilians-Universität Würzburg

08/21/2020
Prof. Dr. Karl Mannheim
Chair of Astronomy
University of Würzburg
mannheim@astro.uni-wuerzburg.de

A new letter has been found in the mysterious alphabet of black holes. Two astrophysicists share this discovery in the journal Nature Communications.

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The centre of quasar 3C279 emits flickering gamma radiation, which is characteristic of the phenomenon of magnetic reconnection. (Image: Amit Shukla / Indian Institute of Technology.)

Black holes are at the center of almost all galaxies that have been studied so far. They have an unimaginably large mass and therefore attract matter, gas and even light. But they can also emit matter in the form of plasma jets – a kind of plasma beam that is ejected from the centre of the galaxy with tremendous energy. A plasma jet can extend several hundred thousand light years far into space.

When this intense radiation is emitted, the black hole remains hidden because the light rays near it are strongly bent leading to the appearance of a shadow. This was recently reported by researchers of the Event Horizon Telescope (EHT) collaboration for the massive black hole in the giant ellipse galaxy Messier 87.

Event Horizon Telescope Array

Arizona Radio Observatory
Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

ESO/APEX
Atacama Pathfinder EXperiment

CARMA Array no longer in service
Combined Array for Research in Millimeter-wave Astronomy (CARMA)

Atacama Submillimeter Telescope Experiment (ASTE)
Atacama Submillimeter Telescope Experiment (ASTE)

Caltech Submillimeter Observatory
Caltech Submillimeter Observatory (CSO)

IRAM 30m Radio telescope, on Pico Veleta in the Spanish Sierra Nevada,, Altitude 2,850 m (9,350 ft)


Institut de Radioastronomie Millimetrique (IRAM) 30m

James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

Large Millimeter Telescope Alfonso Serrano
Large Millimeter Telescope Alfonso Serrano

CfA Submillimeter Array Mauna Kea, Hawaii, USA, Altitude 4,080 m (13,390 ft)

Submillimeter Array Hawaii SAO

ESO/NRAO/NAOJ ALMA Array
ESO/NRAO/NAOJ ALMA Array, Chile

South Pole Telescope SPTPOL
South Pole Telescope SPTPOL

Future Array/Telescopes

IRAM NOEMA in the French Alps on the wide and isolated Plateau de Bure at an elevation of 2550 meters, the telescope currently consists of ten antennas, each 15 meters in diameter.interferometer, Located in the French Alpes on the wide and isolated Plateau de Bure at an elevation of 2550 meters

NSF CfA Greenland telescope


Greenland Telescope

ARO 12m Radio Telescope, Kitt Peak National Observatory, Arizona, USA, Altitude 1,914 m (6,280 ft)


ARO 12m Radio Telescope

Caltech Owens Valley Radio Observatory, located near Big Pine, California (US) in Owens Valley, Altitude1,222 m (4,009 ft)

Messier 87*, The first image of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via JPL/ Event Horizon Telescope Collaboration.

In quasar 3C279 – also a black hole – the EHT team found another phenomenon: At a distance of more than a thousand times the shadow of the black hole, the core of a plasma jet suddenly lit up. How the energy for this jet could get there as if through an invisible chimney was not yet known.

Extremely flickering gamma radiation detected

This quasar has now been observed with the NASA space telescope Fermi-LAT by the astrophysicist Amit Shukla, who until 2018 did research at Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany.

NASA/Fermi LAT


NASA/Fermi Gamma Ray Space Telescope

He now is working at the Indian Institute of Technology in Indore. Shukla discovered that the core of the jet, which was found in the millimeter wavelength range, also emits high-energy gamma radiation, but with an extremely flickering brightness. This brightness can double within a few minutes, as reported in the journal Nature Communications.

The special pattern of the sequence of brightness changes is characteristic of a universal process called magnetic reconnection, which occurs in many astrophysical objects with strong magnetic fields.

NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

Solar activity also has to do with the dynamics of magnetic fields and reconnection. This was recently demonstrated by observing “campfires” in the solar atmosphere with the “Solar Orbiter” mission of the European Space Agency ESA.

ESA/NASA Solar Orbiter depiction

Invisibly stored energy is suddenly released

But back to the quasar 3C279: “I saw how the analysis of the data revealed the special pattern of magnetic reconnection in the light curve. It felt as if I had suddenly deciphered a hieroglyph in the black hole alphabet,” says Amit Shukla happily.

During reconnection, energy that is initially stored invisibly in the magnetic field is suddenly released in numerous “mini-jets”. In these jets, particles are accelerated, which then produce the observed gamma radiation. Magnetic reconnection would explain how the energy reaches the jet’s core from the black hole and where it ultimately comes from.

Energy from the spinning black hole

Professor Karl Mannheim, head of the JMU Chair of Astronomy and co-author of the publication, explains: “Spacetime near the black hole in the quasar 3C279 is forced to swirl around in corotation. Magnetic fields anchored to the plasma around the black hole expel the jet slowing down the black hole’s rotation and converting part of its rotational energy into radiation”.

See the full article here.

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