In an active galaxy, however, the supermassive black hole behaves a lot differently. Rather than devouring anything that ventures too close to them, the black holes at the centers of most galaxies only give away their existence through subtle effects on nearby stars. Frustratingly, its exact location continues to elude detection. ©Kimura et al.This cluster of galaxies is estimated to have a black hole of up to 100 billion solar masses near its center. The future X-ray satellites can detect the signals by the magnetic reconnection in the vicinity of the black holes, which will unravel the plasma loading mechanism to the radio jets.
The blue line with a shaded region in the right panel exhibits the photon spectrum of currently observed long-term flare. The data points in the left panel are the observed photon spectrum during a quiescent state. HiZ-GUNDAM and FORCE are the planned X-ray satellites, whose sensitivities are shown in black dashed lines. The left panel shows the case for M87 and the right for Sgr A*. Photon spectra produced by magnetic reconnection in the vicinity of the black hole. "Under this scenario, future X-ray astronomy will be able to unravel the plasma loading mechanism into radio jets, a long-standing mystery of black holes," points out Shigeo Kimura, lead author of the study.ĭetails of Kimura and his team's research were published in the Astrophysical Journal Letters on September 29, 2022. These X-ray signals are missed with current X-ray detectors, but they are observable by planned X-ray detectors. For example, radio jets around Sgr A* - the supermassive black hole in our Milky Way - are too faint and undetectable by current radio facilities.Īlso, the scenario predicts short-term X-ray emission when plasma is loaded into radio jets. Additionally, the scenario makes note that radio signal strengths vary from black hole to black hole. This explains the large amount of plasma observed in radio jets, consistent with the M87 observations. The present scenario proposes that the emitted gamma rays interact with each other and produce copious electron-positron pairs, which are loaded into the radio jets.
Plasmas in solar flares give off ultraviolet and X-rays whereas the magnetic reconnection around the black hole can cause gamma-ray emission since the released energy per plasma particle is much higher than that for a solar flare. This magnetic reconnection provides the energy source for solar flares. Then, neighboring magnetic energy transiently releases its energy via magnetic reconnection, energizing the plasma surrounding the black hole. Recent studies have claimed that black holes are highly magnetized because magnetized plasma inside galaxies carries magnetic fields into the black hole. Now, a research team, led by Tohoku University astrophysicists, has proposed a promising scenario that clarifies plasma loading mechanism into radio jets. The observation supported the theory that the spin of the black hole powers radio jets but did little to clarify the plasma loading mechanism. Recently, the Event Horizon Telescope Collaboration uncovered radio images of a nearby black hole at the center of the giant elliptical galaxy M87. But much remains unknown about how they are produced, especially their energy source and plasma loading mechanism. Radio jets were first discovered in the 1970s. Some supermassive black holes launch fast-moving plasma outflows which emit strong radio signals, known as radio jets. Galaxies, including our Milky Way, host supermassive black holes in their centers, and their masses are millions to billions of times larger than the Sun.
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