The Event Horizon Telescope peered into the heart of a quasar

Thanks to a worldwide collaboration between scientists, the Event Horizon telescope has plunged into the heart of a quasar to study its most intimate areas. Quasars are extremely powerful radiation sources located in the centers of distant galaxies. Their fulcrums are supermassive black holes that channel accelerated particles and radiation into thin, bright jets. Astronomers are trying to understand the complicated physics of these cosmic monsters, they want to understand how their jets are fed and formed and what is the role of magnetic fields in their formation.

The EHT thus provides an extremely high and unprecedented resolution, enabling astronomers to visualize structures never seen before in the very central region of a quasar known as NRAO 530.

The development of the EHT

The EHT collaboration uses different imaging algorithms to get details about the structure of an object on many fine scales that are opaque at longer wavelengths. They were employed to obtain the first image of the shadow of the black hole in the active galaxy M87 in 2019. The EHT allows scientists to study the magnetic field structure in the vicinity of the black hole and in the innermost part of the jet by observing the behavior of polarized light.

The figure shows the images of the quasar NRAO 530 obtained with different methods in total and polarized light, presented in a new scientific article and reveal a luminous characteristic located at the southern end of the jet, which the authors associate with the nucleus.

In quasars such as NRAO 530, the nucleus shows the point at which the jet starts at a given wavelength. The core has a substructure of two components, which is impossible to solve at longer wavelengths. The jet extends for the distance that the light crosses in about 1.7 years in projection on the celestial plane and has two characteristics with orthogonal polarization directions (angle of position of the electric vector, EVPA)parallel and perpendicular to the direction of the jet.

Scientists interpret it as indicating a helical structure of the magnetic field in the jet.

Artistic representation of the quasar P172+18. Credit: ESO/M. Kornmesser

NRAO 530 is the most distant object we’ve taken with the EHT so far. The light we see has traveled to Earth for 7.5 billion years through the expanding Universe, but with the power of the EHT you can observe the details of the source structure on a scale as small as a single light year.

Astronomers eagerly await future observations of the quasar to understand how the characteristics of the innermost jet and its connection to high-energy photon production change over time, since NRAO 530 is a well-known source of powerful gamma rays. 

References: EHT

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