An article published in “The Astrophysical Journal” reports the study of the quasar NRAO 530 conducted within the EHT (Event Horizon Telescope) project, which uses a combination of radio telescopes around the world to obtain images of areas around supermassive black holes. In this case, these are the innermost areas of NRAO 530, where gas and dust are heated to the point of generating strong electromagnetic emissions. About 7.5 billion light-years from the Earth, it’s the farthest supermassive black hole observed so far by the EHT project. The new details obtained on the structures present in this quasar’s central region are useful to understand the processes taking place in that extreme environment.
The EHT project gained fame far beyond the field of astronomy with the publication of the first image of the area around the supermassive black hole at the center of the galaxy M87. That was only the first publicly disclosed study of those conducted combining synchronized observations from several radio telescopes using a technique called very-long-baseline interferometry (VLBI).
Different methods have been developed to generate the images from the EHT project’s data: eht-imaging, SMILI, DMC, and Themis, which were added to the classic CLEAN method, used by the DIFMAP software. The image (Courtesy S. Jorstad, M. Wielgus, et al., Apj, 2023) shows the results of the observations of the quasar NRAO 530 produced using the various methods.
A team of researchers including the ones from the EHT Collaboration used the quasar NRAO 530 in April 2017 to calibrate the project’s radio telescopes because it’s an object that has already been known for quite some time and studied with different instruments. One could argue that this result is a byproduct of the process that led to the historic image of M87 and later that of Sagittarius A*, the supermassive black hole at the center of the Milky Way. However, NRAO 530 is also an interesting object of study and its observation provided information useful to astronomers.
Despite the distance, the EHT captured never-before-seen details of the quasar NRAO 530. Various structures detected in its central region, called radio core in jargon, were never seen before and are useful for better understanding the ongoing processes. The images also reveal a jet of particles ejected at near-light speeds spanning approximately 1.7 light-years with substructures indicating the presence of a helical magnetic field along the jet.
The quasar NRAO 530 is also known as a gamma ray source, and astronomers are interested in understanding how those very high-energy photons and the characteristics of the relativistic jet change over time. In essence, NRAO 530 was observed in 2017 in the EHT project’s calibration phase but the scientists of the EHT Collaboration intend to conduct new observations to obtain further information on the processes taking place in that extreme environment.
