Flare
Zelch Csaba/Pexels

Astronomers were baffled after they observed a mid-infrared flame from the central black hole of the Milky Way. It lasted for nearly an hour, which led scientists to new clues on how the outbursts started.

JWST's MIRI Detects Infrared Flare From Satigarrius A*

James Webb Space Telescope's mid-infrared instrument (MIRI) noticed an infrared flare from the Milky Way's supermassive black hole, Sagittarius A*. It was the first time they observed such an event in that part of the spectrum.

The team led by Sebastiano von Fellenberg, a postdoctoral researcher at the Max Planck Institute, analysed MIRI data and identified a flare on 6 April 2024. The outbursts reportedly lasted 40 minutes, and, according to modelling, the magnetic fields in the emitting zone were about 40 to 70 Gauss, Earth.com reported.

The Submillimeter Array (SMA), which comprises eight six-meter-diameter radio telescopes, corroborated the sighting by detecting a matching signal.

Why Was There a Flare?

According to the researchers, the flare happened due to magnetic reconnection.

'Our research indicates that there may be a connection between the observed variability at millimetre wavelengths and the observed mid-IR flare emission,' Fellenberg said.

High-energy electrons could be the cause of the signals. When they are near a black hole where magnetic fields are strong, electrons can accelerate near light speed via magnetic reconnection. This leads them to spiral along magnetic field lines, emitting synchrotron radiation, which is observed as infrared or X-ray flares.

The energy loss is what is detected as the burst of light.

Initially, when electrons are extremely energetic, they appear as bright flares, and the flares fade as they lose energy. At first, they are in mid-IR when ultra hot and following the drop of energy, their emission shifts to longer wavelengths.

The lag between wavelengths helps astronomers understand electron cooling rates, magnetic field strength, and plasma properties near the black hole.

Black Hole Sagittarius * And Flares

Sagittarius A* is the supermassive black hole in the centre of the Milky Way. It is 26,500 light-years from Earth and four million times the mass of the Sun.

Due to gravity, objects move towards it, and the closer they are to the black hole's event horizon, the stronger the gravitational pull.

When a matter or light crosses this boundary, there's no coming back because the escape velocity exceeds the speed of light. Hence, the event horizon is called 'point of no return.'

A black hole doesn't suck objects; the spiralling gas and dust that heat up and emit light create the visual effect of a cosmic vacuum, but it doesn't pull anything into it. Space matters fall into it when they are close enough or when they lose energy.

Scientists study flares near a black hole's event horizon to learn its extreme gravitational and magnetic conditions. This also lets them test general relativity in strong gravity that can't be found elsewhere.

Flares illuminate the extreme environment near the black hole, revealing the physics of gravity, magnetism, and high-energy particles.

Writer's pick