After capturing the first images of black holes, the Event Horizon Telescope (EHT) is ready to unveil the mechanism by which black holes launch powerful jets into space. An international team of over 400 researchers, with significant participation from the University of Valencia (UV), has demonstrated that the EHT will be able to obtain remarkable images of a supermassive black hole and its jets in the galaxy NGC 1052. Measurements carried out using interconnected radio telescopes located on several continents confirm the presence of strong magnetic fields near the edge of the black hole. The study has been published in the journal Astronomy & Astrophysics
The key question posed by the scientists behind the project was how supermassive black holes launch streams of high-energy particles—known as jets—into space, which traverse the galaxy at nearly the speed of light. Scientists have now taken an important step towards answering this question with intricate measurements of the centre of the galaxy NGC 1052, located 60 million light-years away from Earth. The aim of this international collaboration is to capture the most detailed images ever obtained of black holes by creating a virtual telescope the size of Earth.
The scientists made coordinated observations using several radio telescopes, providing new insights into the functioning of a galaxy and its supermassive black hole. These telescopes include those in the Event Horizon Telescope (EHT), which capture radiation at a wavelength of 1.3 mm, and in the Global mm-VLBI Array (GMVA), which operate at 3.5 mm. The technique combining these telescopes is known as very-long-baseline interferometry (VLBI). The findings are reported in an article published in the scientific journal Astronomy & Astrophysics on 17 December 2024.
The study was led by Anne-Kathrin Baczko, an astronomer at the Onsala Space Observatory in Chalmers (Sweden), and Manel Perucho, professor of Astrophysics at the UV and one of the lead authors of the article. “The centre of this galaxy, NGC 1052, is a promising target for imaging with the EHT, but it is faint, complex and more challenging than all the other sources we have observed so far”, explains Anne-Kathrin Baczko. The galaxy has a supermassive black hole at its centre, which is the source of two powerful jets that extend thousands of light-years into space.
“The observations confirm that the formation, acceleration and collimation of extragalactic jets are linked to the presence of intense magnetic fields in the black hole’s environment. These observations bring us closer to understanding one of the most enduring mysteries of modern astrophysics”,explains Manel Perucho. Iván Martí Vidal, professor at the UV and collaborator in the study, developed the calibration methods used in the analysis to reveal the structure of the magnetic fields. Martí Vidal affirms: “The UV’s contribution has been crucial to this study and to the EHT project in general”.
“We aim to study not only the black hole and its extreme environment, but also the origin of the twin jets that emanate from it. We have taken advantage of the combination of GMVA and EHT to focus on an especially important and key object at the intersection of different types of active galaxies”, says Eduardo Ros, aprofessor from the UV on leave of absence, affiliated with the Max Planck Institute for Radio Astronomy in Bonn (Germany), and a member of the research team.
The team conducted observations using only five of the telescopes in the global EHT network, configured to provide the best possible estimation of their potential for future observations and supplemented with measurements from other telescopes, including the GMVA. The scientific team is confident in the possibility of successfully capturing images in the future thanks to two crucial new pieces of data. First, the black hole’s surroundings emit at just the right radio wavelength to be measured with mm-VLBI, and second, the size of the region where the jets form is similar to that of the M87 ring, which is large enough to be observed with mm-VLBI.
Magnetic field strength
From their measurements, scientists have also calculated the strength of the magnetic field near the black hole’s event horizon. At 2.6 teslas, the intensity is approximately 400 times stronger than Earth’s magnetic field. “This is such a powerful magnetic field that we believe it could probably prevent some of the material from falling into the black hole. This, in turn, could help launch the twin jets from the galaxy”, concludes Matthias Kadler, an astronomer at the University of Würzburg (Germany).
The research team includes Manel Perucho among the article’s leaders. Other researchers affiliated with the University of Valencia and co-authors of the article are Ezequiel Albentosa-Ruiz, Rebecca Azulay and Iván Martí Vidal. Other Spanish institutions participating in the study include the Institute of Astrophysics of Andalusia and the Institute for Millimetre Radio Astronomy, both in Granada.
The measurements were conducted by five telescopes in the EHT network: ALMA (Atacama Large Millimeter/submillimeter Array) in Chile; the IRAM 30-metre telescope in Pico Veleta, Sierra Nevada; the James Clerk Maxwell Telescope (JCMT) and the Submillimeter Array (SMA) in Hawaii; and the South Pole Telescope (SPT) in Antarctica. These were complemented by measurements from 14 other radio telescopes in the GMVA (Global Millimetre VLBI Array).
Caption:
Close-up of the black hole at the centre of NGC 1052 (artist’s impression). How do black holes launch their powerful jets? In this visualisation of the galaxy’s core, we zoom through layers of gas and dust to nearly reveal the supermassive black hole. New measurements now show that a close-up of the black hole—and the source of its jets—are within reach of the Event Horizon Telescope (Image credit: Chalmers/J. Bournonville/Anne-Kathrin Baczko).
Article reference:
Anne-Kathrin Baczko et al. «The putative center in NGC 1052». Astronomy & Astrophysics. DOI: https://doi.org/10.1051/0004-6361/202450898
Source: UV Notícies