Astronomers have observed the outer edge of the disc of matter surrounding a supermassive black hole for the first time.
These observations can help scientists better measure the structures surrounding these cosmic monsters, understand how black holes feed on these structures, and deduce how black holes influence the evolution of the galaxies that host these phenomena.
Feeder black holes are located at the heart of a region of extraordinary brightness called the active galactic nucleus (AGN). Directly around these black holes, which can be millions or even billions of times larger than the Sun, there is a rotating disk of gas and dust that is gradually being fed into the center of the supermassive object.
The tremendous gravitational effects of supermassive black holes cause matter in the accretion disk to reach temperatures of up to 18 million degrees Fahrenheit (10 million degrees Celsius). This causes the structure to emit radiation across the entire electromagnetic spectrum, from high-energy gamma rays and X-rays to visible light, infrared, and radio waves. Emissions from active galactic nuclei, which are also called quasars, can be so bright that they exceed the combined light of every star in the surrounding galaxy.
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However, even with this strong output, because accretion disks are relatively small and many are located in very distant galaxies, they are difficult to image directly. But alternatively, astronomers can use the full spectrum of light from the accretion disk to understand its physics and even determine its size.
This technique was adopted by a team led by researchers from the National Institute of Space Research in Brazil. Dinemara Dias dos Santos and Alberto Rodríguez Ardela studied the accretion disk of a distant quasar, III Zw 002, which lies at the heart of the galaxy Messier 106 (M 106). M 106 lives about 24 million light years from Earth in the constellation Canes Venatic.
The team saw for the first time near-infrared emission lines in the light spectrum coming from this quasar’s accretion disk. These lines help researchers determine the size of the plate-like structures that are the source of the supermassive black hole, which is estimated to have a mass between 400 and 500 times that of the Sun.
“This discovery gives us valuable insight into the structure and behavior of broadband regions in certain galaxies, shedding light on the interesting phenomena that occur around supermassive black holes in active galaxies,” Rodriguez-Ardela he said in a statement.
Excitement about accumulation tablets
Emission lines as the team studied occur when an atom absorbs energy and adopts what physicists call an “excited state”. Ultimately, these atoms must return to their lowest energy state, or “ground state.” This descent to the ground state causes the release of light, as each element has a unique energy level, wavelength, and energy characteristic of that particular element’s atom.
This means that this emission spectrum of light can help identify elements in stars, planetary atmospheres, and, in this case, the accretion disk around a black hole.
Emission lines from stars and other sources appear as slight bumps on the spectrum, but the violent conditions around supermassive black holes cause the emission lines of the accretion disk to appear distinct.
When matter near a supermassive black hole accelerates to near the speed of light, the associated emission lines widen and reach shallower peaks. The region of origin of this emission is referred to as the outline region of the accretion disk.
When one side of the accretion disk moves toward Earth, the other side moves away. This results in shorter wavelengths of light on the side that is rotating towards us and longer wavelengths of light on the side that the accretion disk is away from.
This is similar to what happens on this earth when an ambulance comes towards you on a city street. Sound waves from sirens combine to produce short-wavelength and high-frequency sound. As the ambulance moves away, the sound waves expand and the siren’s frequency decreases.
This phenomenon is called the Doppler shift, and the light leaving the accretion disk causes two peaks to appear – one on the side that is moving away from Earth and the other on the side that is moving fast towards Earth.
When this dilated, double-peaked emission is seen coming from the interior of the accretion disk, it doesn’t give astronomers any clue as to the size of the accretion disk. However, if these lines can be seen from the outside edge, then they are.
The team of astronomers has decisively detected two near-infrared profiles with double peaks in broadband region III Zw 002, a line originating from hydrogen from the inner region of the wideband disk and oxygen-producing lines at the outer boundary of this region. .
The emission lines were found in data collected by the Gemini Near Independent Spectrograph (GNIRS), which is able to simultaneously observe the entire near-infrared spectrum. This allowed the team to capture the spectrum of a single, clean, continuously calibrated quasar.
“Before we didn’t know that III Zw 002 had the appearance of this double peak, but when we reduced the data, we saw the double peak very clearly,” said Rodriguez Ardilla. “In fact, we reduced the data several times thinking it might be wrong, but each time we saw the same compelling results.”
This helped limit the size of the accretion disk, as the team could see that the hydrogen lines were from a distance of 16.77 light days from the center of the supermassive black hole, while the oxygen lines were from a radius of 18.86 light days. .
Astronomers were also able to determine the size of the broad outline region, and estimate its outer radius to be 52.43 light days. In addition, the team was able to calculate that the broad outline region of the accretion disk is tilted at an angle of 18 degrees with respect to Earth.
The team will continue to observe quasar III Zw 002, watch its image change over time, and use near-infrared light to study other AGNs.
This research was published in August Astrophysics Journal Letter.
2023-09-05 22:48:37
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