FINANCIAL – An international team of astronomers, including University of Massachusetts professors Gopal Narayanan and Peter Schloerb, has just discovered a new view of a massive black hole at the center of a galaxy 55 million light-years away, known as the M87 Galaxy. This new image, recorded by the Horizon Event Telescope Collaboration (EHT), shows what the M87 looks like in polarized light and was published today in two papers published in The Astrophysical Journal (links here and here). This is the first time that astronomers have been able to measure polarization, the signature of magnetic fields, so close to the edge of a black hole. Observations are key to explaining how the galaxy M87 is capable of launching energy jets from its core, Notes from the University of Massachusetts.
“At the center of almost every galaxy is a supermassive black hole,” Narayanan explains. These black holes power galactic nuclei, which often launch high-energy jets from the central parts of the galaxy. Understanding the physics that connects supermassive black holes and galactic jets was difficult. This is where the polarization of light occurs.
Light becomes polarized when it passes through certain filters, such as the lenses of polarized sunglasses, or when it is emitted in hot parts of space that are magnetized. In the same way polarized sunglasses help us see better by reducing reflections and glare from bright surfaces, astronomer
Light becomes polarized when it passes through certain filters, such as the lenses of polarized sunglasses, or when it is emitted in hot parts of space that are magnetized. In the same way that polarized sunglasses help us see better by reducing reflections and glare from bright surfaces, astronomers can sharpen their vision of the region around a black hole by seeing how the light that polarizes from there is polarized. Specifically, polarization allows astronomers to map the magnetic field lines present at the inner edge of a black hole. “The magnetic fields and jets were previously mapped,” says Narayanan, “but at a lower resolution. We can now zoom in on the energy launch areas of these nozzles with amazing resolution and map the nozzles in a way never before done. “
“Now we see the following crucial evidence to understand how magnetic fields behave around black holes and how activity in this very compact space region can propel powerful jets that extend far beyond the galaxy,” says Monika Mościbrodzka, coordinator of the EHT polarimetry working group and assistant professor. at Radboud University in the Netherlands, Notes from the University of Massachusetts.
Astronomers have relied on various patterns of behavior of matter near a black hole to better understand this process. But they still don’t know exactly how jets larger than a galaxy launch from its central region, or exactly how matter falls into a black hole. With the new EHT image of a black hole and its shadow in polarized light, astronomers have for the first time been able to look into the area just outside the black hole where the interaction of matter entering and exiting takes place. “What is particularly noticeable in this observation,” says Schloerb, “is that by measuring polarization you really get the properties of the magnetic field, which is so important because it helps us understand the basic physics of galaxy evolution.”
To observe the heart of the M87 galaxy, the collaboration connected eight telescopes around the world, including the Large Millimeter Telescope (LMT), jointly operated by UMass and the country of Mexico, and the largest of its kind. Narayanan, who leads UMass ’EHT team, built a radio astronomy receiver for the LMT that helped collect data on the M87 black hole. The impressive resolution obtained by EHT is equal to that required to measure the length of a credit card on the Moon’s surface.
This setting allowed the team to directly observe the shadow of the black hole and the light ring around it, with a new image of polarized light that clearly shows that the ring is magnetized. The results were published today in two separate papers in The Astrophysical Journal Letters by an EHT contributor. The research involved over 300 researchers from several organizations and universities around the world.
“Discovering this new image of polarized light required years of work due to the complex techniques involved in data acquisition and analysis,” says Iván Martí-Vidal, coordinator of the EHT Polarimetry Working Group and a renowned GenT researcher at the Universitat de València, Spain.
“What fascinates me the most is tracking,” Narayanan says. “We now have even more sensitive receivers, and with more sensitive instruments we can extract more details into magnetic fields. We have even more exciting data and analyzes ahead of us.