Composite image of the supermassive black hole at the center of the Milky Way galaxy. Credit: X-ray: NASA / CXC / SAO; IR: NASA / HST / STScI. Insert: Radio (EHT Collaboration)
The black hole in the center of our galaxy is the subject of an innovative new image from the collaboration of the Event Horizon Telescope.
As the Event Horizon telescope collected data on its remarkably new image of the supermassive black hole in the Milky Way, a legion of other telescopes, including three NASA X-ray observatories in space, also observed.
Astronomers use these observations to learn more about how the black hole at the center of the Milky Way galaxy – known as Sagittarius A * (Sgr A * for short) – interacts and feeds on the environment about 27,000 light-years from Earth.
When the Event Horizon Telescope (EHT) observed Sgr A * in April 2017 to make the new image, the collaborating scientists also peered into the same black hole with equipment that detects different wavelengths of light. In this multi-wave observation campaign, they collected X-ray data from NASA’s Chandra X-ray Observatory, Nuclear Spectroscopy Telescope (NuSTAR) and Neil Gerells Swift Observatory; radio data from the East Asian very long basic interferometer (VLBI) network and the global 3 mm VLBI grid; and infrared data from the very large telescope of the European Southern Observatory in Chile.
“The Event Horizon telescope captured another remarkable image, this time of the giant black hole at the center of our own galaxy,” said NASA Administrator Bill Nelson. “Examining this black hole in more detail will help us learn more about its space effects on the environment and set an example of international cooperation that will transport us into the future and reveal discoveries we could never have imagined.
One important goal was to capture X-ray eruptions, which are thought to be driven by magnetic processes similar to those observed in the sun, but can be tens of millions of times more powerful. These eruptions occur approximately daily in the area of the sky observed by the EHT, a region slightly larger than the event horizon of Sgr A *, the point of no return of matter falling inward. Another goal was to get a critical look at what was happening on a larger scale. While the EHT result shows striking similarities between Sgr A * and the previous black hole it depicted, M87 *, the broader picture is much more complex.
“If the new EHT image shows us the eye of a black hole hurricane, then these multiwave observations reveal winds and rain equivalent to hundreds or even thousands of miles beyond,” said Daryl Haggard of McGill University in Montreal, Canada, one of them. of the leading scientists of the multi-wave campaign. “How does this cosmic storm interact and even disrupt its galactic environment?”
One of the biggest current questions about black holes is how exactly they collect, absorb, or even throw away material around them at close speeds of light, in a process known as “accumulation.” This process is fundamental to the formation and growth of planets, stars and black holes of all sizes throughout the universe.
Chandra’s images of hot gas around Sgr A * are crucial to accretion research because they tell us how much material was captured by nearby stars by black hole gravity, and how much it manages to make its way near the event horizon. This critical information is not available with current telescopes for any other black hole in the universe, including M87 *.
“Astronomers can largely agree with the basics – that black holes have material that revolves around them and some of it falls over the horizon of events forever,” said Sera Markoff of the University of Amsterdam in the Netherlands, another coordinator. multiwave observations. “With all the data we’ve collected for Sgr A *, we can go much further than this basic picture.”
Scientists in large-scale international collaboration are comparing data from NASA’s high-energy missions and other telescopes with state-of-the-art computational models that take into account factors such as Einstein’s general theory of relativity, magnetic field effects and estimates of how much radiation the black hole must generate. at different wavelengths.
A comparison of the models with the measurements suggests that the magnetic field around the black hole is strong and that the angle between the line of sight to the black hole and its axis of rotation is low – less than about 30 degrees. If confirmed, this means that from our point of view we are looking down at Sgr A * and its ring more than from the side, surprisingly similar to the first target of EHT, M87 *.
“None of our models match the data perfectly, but we now have more specific information to work with,” said Kazuhiro Hada of the National Astronomical Observatory of Japan. “The more data we have, the more accurate our models will be and ultimately our understanding of black hole accumulation.”
The researchers also managed to capture X-ray bursts – or bursts – of Sgr A * during EHT observations: weak, observed in Chandra and Swift, and moderately bright, observed in Chandra and NuSTAR. X-ray eruptions of similar brightness to the latter are observed regularly with Chandra, but this is the first time that EHT has simultaneously observed Sgr A *, offering an exceptional opportunity to identify the responsible mechanism using actual images.
The intensity and variability of millimeter waves observed in EHT increased in a few hours immediately after the brighter X-ray wave, a phenomenon not observed in millimeter waves a few days earlier. Analysis and interpretation of EHT data immediately after the outbreak will be reported in future publications.
The results of the EHT team will be published on May 12 in a special issue of The Astrophysical Journal Letters. The results of many waves are described mainly in documents II and V.
Breaking a black hole: How the EHT super telescope works
Citation: NASA supports Event Horizon Telescope in the study of the Black Hole on the Milky Way (2022, May 13), extracted on May 13, 2022 from
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