Event Horizon Telescope: Moving towards a close-up of a black hole and its jets

The main research question for scientists on the project is how do supermassive black holes launch galaxy-sized streams of high-energy particles, called jets, into space at nearly the speed of light? Now, scientists have taken an important step toward answering this question by performing sophisticated measurements of the center of the galaxy NGC 1052, 60 million light-years from Earth.

Scientists’ coordinated measurements using multiple radio telescopes have provided new insights into the workings of galaxies and their supermassive black holes. The results are published in a paper in the scientific journal Astronomy and Astrophysics December 17, 2024.

A promising but challenging goal

The work was led by astronomer Anne-Kathrin Baczko of the Onsala Space Observatory at Chalmers University of Technology.

“The center of this galaxy, NGC 1052, is a promising target for imaging with the Event Horizon Telescope, but it is fainter, more complex and more challenging than all other sources we have tried so far,” Anne-Catherine Bazko (Anne-Kathrin Baczko) said.

The galaxy has a supermassive black hole that is the source of two powerful jets that extend thousands of light-years out through space.

“We have to study not only the black hole itself, but also the origin of the jets that erupt from the east and west sides of the black hole as seen from Earth,” said astronomer Eduardo Ross, a member of the Max Planck Observatory team at Bonn Radio in Germany. Institute of Astronomy.

The team conducted the measurements using only five telescopes in the EHT’s global network, including ALMA (Atacama Large Millimeter/submillimeter Array) in Chile, configured to provide the best estimate of its potential for future observations. and complement measurements with other telescopes.

“With such a faint and unknown target, we were not sure we would be able to obtain any data. But the strategy worked, especially thanks to ALMA’s sensitivity and complementary data from many other telescopes,” Anne-Catherine Bazko Anne-Kathrin Baczko said.

Measurements suggest successful imaging may be possible in the future

• Scientists are now convinced that successful imaging in the future will be possible thanks to two new key pieces of information: The radio waves around the black hole shine brightly at just the right frequency to ensure that the EHT can measure it.

• The size of the region where the jets form is similar to that of M 87*’s rings – large enough to be imaged with the full power of the EHT.

Through measurements, scientists also estimated the strength of the magnetic field near the black hole’s event horizon. The magnetic field strength is 2.6 Tesla, which is approximately 40,000 times the Earth’s magnetic field. This is consistent with previous estimates for this galaxy.

“This is such a strong magnetic field that we think it might be able to prevent matter from falling into the black hole. This in turn could help launch the galaxy’s two jets,” said Matthias Kadler.

Despite such challenging sources, the future looks bright as radio astronomers prepare for new generation telescope networks, such as NRAO’s ngVLA (Next Generation Very Large Array) and ngEHT (Next Generation Event Horizon Telescope).

“Our measurements give us a clearer understanding of how the innermost center of the galaxy shines at different wavelengths. Its spectrum is bright at wavelengths of around a millimeter, where we can take the sharpest images today. It is slightly brighter at wavelengths of around a millimeter. It is even brighter at longer wavelengths, making it a prime target for next-generation radio telescopes.

More information about the study

The research paper “Presumptive Centers in NGC 1052” by Anne-Kathrin Baczko (Chalmers University of Technology, Sweden) and 286 co-authors is published in the journal Astronomy and Astrophysics. The research team also includes Chalmers University of Technology scientists John Conway and Michael Lindqvist (both from the Onsala Space Observatory) and Chiara Ceccobello (now working at a Swedish AI company).

The measurements were made by five telescopes in the EHT network: ALMA (Atacama Large Millimeter/submillimeter Array) in Chile, the IRAM 30-meter telescope in Spain; and the James Clerk Maxwell Telescope (JCMT) in Hawaii. and Submillimeter Array (SMA); and the South Pole Telescope (SPT) in Antarctica. These data are supplemented by 14 other radio telescopes in the GMVA network (Global Millimeter Wave VLBI Array) in Spain, Finland and Germany, including the 20-meter telescope at the Onsala Space Observatory in Sweden and the VLBA (Very Long) Telescope Baseline array) in the United States.

The EHT collaboration involves more than 400 researchers from Africa, Asia, Europe, North and South America. The international collaboration aims to capture the most detailed images ever of a black hole by creating a virtual Earth-sized telescope.