The telescopes have captured the moment of black hole birth
The unusually bright flare AT2018cow recorded last year was among the brightest on record. Initially, astronomers did not know what they were dealing with, but after looking closely at the event, they concluded that the observatories had, for the first time ever, captured the exact moment of birth of a black hole or neutron star.
On June 17, 2018, an incredibly bright flare lit up the night sky. It was recorded by the twin ATLAS telescopes in Hawaii. Astronomers have determined that it took place in the constellation Hercules, ktory is located at a distance of about 200 millionoin light years away. A bright anomaly called AT2018cow or simply „The Cow” (The Cow), disappeared roas quickly as it appeared.
International teamoł scientistsow after combining several sourcesoimaging sources, including X-rays and radio waves, he said, the telescopes have captured a moment in which theorym star has collapsed to form a compact object, such as a black hole or neutron star. This rare event will help astronomers better understand the processes involved in the first moments of the formation of this type of objectow.
– Cow is believed to be the birth of an accreting black hole or neutron star. We know from theory that black holes and neutron stars form when a star dies, but we’ve never seen them right after birth – said Raffaella Margutti of Northwestern University.
The findings of the Margutti-led team were presented at the American Astronomical Society meeting and will be published in the journal „Astrophysical Journal”.
Cow almost immediately attracted the interest of the international community of astronomersow. But researchers weren’t sure what they were actually dealing with. – We thought it must be a supernova, but what we observed challenged our current notions about the death of a star – explained Margutti.
The observed anomaly was unnaturally bright, 10 to 100 times brighter than a typical supernova. The flare disappeared much faster than other known stellar explosions. In just 16 days, the object emitted most of its energy. In the Universe, whichorym some phenomena last millions or even billions of years, two weeks is the blink of an eye.
– We knew immediately that it was the source of theobottom went from being inactive to having peak light intensity in just a few days. This was enough to get everyone excited – admitted Margutti, and added that the excitement was magnified by the fact that, according to astronomical standardsow, the observed anomaly was very close.
Astronomers from Margutti’s team using a telescopeoat Kecka in Hawaii and the MMT Observatory in Arizona, and with access to the SoAR telescope in Chile, they took a close look at the Cow. They examined its chemical composition finding clear evidence of hydrogen and helium, ktore precluded the merger of compact objectsoin, such as those producing gravitational waves.
Syndromeoł Margutti, in addition to examining the object in the optical wavelength, used a more comprehensive approach. Scientists used X-rays, hard X-rays (10 times stronger than ordinary X-rays), radio waves and gamma rays in the study. This enabled further study of the anomaly long after its initial brightness had faded.
Although stars can collapse into black holes all the time, a large amount of material wokoł newborn black holes obstruct astronomers’ view. Fortunately, the wokoł The cow circulated about 10 times less material in the poroIn comparison to a typical stellar explosion. Its absence has allowed astronomers to look straight into the "central engine" object, whichory revealed as a likely black hole or neutron star.
– It would have been difficult to see in a normal stellar explosion, but the Cow had a very small ejecta mass, allowing us to see directly the radiation from the central engine – explained Margutti.
Although the flare was located in a distant dwarf galaxy named CGCG 137-068 located at a distance of about 200 millionoin light years, according to the standardoin astronomy, this "just around the corner". – This is the closest transient object of its kind we’ve ever found – noted Margutti.
Sourceobackground: Northwestern University, photo. Raffaella Margutti/Northwestern University