A team of astronomers have discovered a supermassive black hole of a few hundred thousand solar masses in a dwarf galaxy, Mrk 462. The discovery of this “small” black hole hidden by gas and matter could allow researchers to learn more about the formation and life cycle of these cosmic phenomena.
Among the cosmic ogres that are supermassive black holes, it sometimes happens to find small specimens. A team ofastronomers has published January 10 a press release reporting the detection of a supermassive black hole in the heart of the dwarf galaxy Markarian 462 (Mrk 462). Located at 110 millionlight years, Mrk 462 turns out to be a compact system although more sparsely populated than other galaxies such as the Milky Way. The researchers used the space telescope Chandra, who has detected several black holes since the start of her mission. Studying the galactic nucleus of Mrk 462 would put scientists on the trail to understanding the evolution of black holes.
Supermassive black hole for a dwarf galaxy
The characteristics of the Mrk 462 black hole are arousing the curiosity of scientists. Jack Parker, astronomer from Dartmouth University (United States), explained during a conference of theAmerican Astronomical Society, on January 10, that ” this supermassive black hole is one of the smallest ever found ”, despite its 200,000 masses solar (, 200,000 times the mass of the Sun, i.e. 1.989 × 1030 kg). Finding this phenomenon in the heart of a dwarf galaxy has proven to be a complex task. Mrk 462 has a particular configuration, aggregating a few hundred millionstars, against hundreds of billions in a spiral galaxy “Classic” such as the Milky Way or M31 (Andromeda). With its status as a dwarf galaxy, Mrk 462 thus has a relatively compact appearance, the supermassive black hole is obscured by the gas and the matter revolving around.
This parameter greatly complicated its detection. In the case of larger galaxies, the discovery of supermassive black holes is usually done through the observation of stars orbiting in its environment, by studying their spectra (in particular the redshift, or redshift) or their speed of gravitation. But, in the case of the Markarian black hole 462, which turns out to be “buried” under a large quantity of gas, the researchers were helped by a device of incredible precision: the telescope Chandra.
Chandra tracks down X-rays
As the material contained in the accretion disc falls towards the event horizon of a black hole, it will experience a sharp increase in the pressure, which will induce monumental heat gain. This will cause X-rays, which some devices such as the Chandra Space Telescope can pick up. Chandra, launched in 1999 by the Nasa, is equipped with three spectrometers and a camera in order to carry out precise observations of objects such as pulsars, retentive of supernovae or black holes, making it one of the most successful observatories of the past 30 years.
The discovery of the Mrk 462 black hole makes it possible to suppose the existence of such phenomena in other dwarf galaxies, and thus to learn more about the evolution of black holes into gargantuan monsters of several million solar masses. Some of them were formed very quickly after the start of theUniverse (about a billion years after big Bang), without the researchers knowing how to explain. If the thesis of thecollapse gravitational force of a massive star in a black hole is the most common today, they could also arise from the collapse of matter in dense clouds of dust and cosmic gas.
If the study of Markarian 462 is only in its early stages, the NASA astronomers do not hide their desire to continue to hunt dwarf galaxies and their black holes to learn more about these mysterious phenomena.
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