In an attempt to elucidate a twenty-year-old mystery, astronomers wanted ” to take the pulse “ of the most massive stellar black hole they know. According to them, the jets of matter that escape from its poles come from a corona of plasma formed while the black hole accretes matter.
For take his pulseit suffices to palpate a artery. The radial artery, most often. The one that passes on the inside of our wrist. Slight pressure and you feel the pulsation of blood flow. A pulse that betrays the beating of our heart. But how to take pulse of a black hole? That’s what astronomers from the University of Groningen (Netherlands) explain to us today.
They were particularly interested in GRS 1915 +105. This black hole is located at about 36,000 light years of our Earth. In our Milky Way. It is one of the heaviest stellar black holes known to researchers. It weighs no less than twelve times more than our Sun. And he has a girlfriend. A star absolutely classic.
Researchers at the University of Groningen, therefore, have collected fifteen years of data on this black hole. Data from multiple telescopes. But they mostly pointed at him, every three days, the Rossi X-ray Timing Explorera space telescope of NASA which operates in the X-rays. And also mobilized the branches of the radio telescope Ryle (UK). All to gather information both on the coronas of ultra hot plasma that form around black holes accreting matter and on their jet radio.
First a crown then a jet
The astronomers compare their work to that of a doctor who takes his patient’s pulse. They underline in fact that in the image of blood which cannot be at the same time in theheadset and in the ventriclesthey now show that the matter and the energy which feeds the system cannot be concentrated simultaneously in the crown of the black hole and in its jet.
For about twenty years, the question has arisen as to whether the crowns of X-rays and the jets radio observed on black holes did not ultimately correspond to one and the same phenomenon. And it is only by relating data on very different time scales — from ten years to a second — and at very different energy levels — from the very high energy at very low — that astronomers from the University of Groningen have come to a conclusion. These two phenomena occur one after the other. The X-ray corona would simply turn into a radio jet.
But the work is not finished. The researchers will now have to explain how the X-ray radiation they have collected from the corona that surrounds the black hole can carry more energy than they explain by the temperature of its surface alone. accretion disk. Perhaps thanks to the existence of a magnetic field. Which could at the same time explain the formation of the jets. A mechanism that astronomers even imagine, why not, apply to the supermassive black hole that hides at the heart of the Milky Way.
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