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American Astronomical Society, Astrophysical Journal, 2(943), p. 170, 2023

DOI: 10.3847/1538-4357/acaea8

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The Event Horizon Telescope Image of the Quasar NRAO 530

Journal article published in 2023 by Svetlana Jorstad ORCID, Maciek Wielgus ORCID, Rocco Lico ORCID, Sara Issaoun ORCID, Avery E. Broderick ORCID, Dominic W. Pesce ORCID, Jun Liu, Jun 俊. Liu 刘. ORCID, Guang-Yao Zhao ORCID, Thomas P. Krichbaum ORCID, Lindy Blackburn ORCID, Chi-Kwan Chan ORCID, Michael Janssen ORCID, Venkatessh Ramakrishnan ORCID, Kazunori Akiyama ORCID and other authors.
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Abstract We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5−7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of ∼20 μas, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ∼5%–8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle ∼ −28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin.