The Event Horizon Telescope Image of the Quasar NRAO 530

分类： 天文学 >> 天文学 提交时间： 2023-02-19

Svetlana Jorstad Maciek Wielgus Rocco Lico Sara Issaoun Avery E. Broderick Dominic W. Pesce Jun Liu Guang-Yao Zhao Thomas P. Krichbaum Lindy Blackburn Chi-Kwan Chan Michael Janssen Venkatessh Ramakrishnan Kazunori Akiyama Antxon Alberdi Juan Carlos Algaba Katherine L. Bouman Ilje Cho Antonio Fuentes Jose L. Gomez

摘要： 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 $\sim$ 20 $\mu$as, both in total intensity and in linear polarization. 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 $\sim$5-8% and has a sub-structure 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 $\mu$as along a position angle PA$\sim -$28$^\circ$. It includes two features with orthogonal directions of polarization (electric vector position angle, EVPA), 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 linear polarization, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on ${\mu}$as scales, while simultaneous multi-wavelength monitoring will provide insight into the high energy emission origin.

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