Monday, September 26, 2022

EHT imaged a violent supermassive black hole with a helically bent jet

Resolving the core of the distant blazar.

Blazars are powerful active galactic nuclei in which supermassive black holes eject relativistic jets directed along our line of sight. A blazar can shine brighter than its galaxy and can be seen with radio telescopes from a distance of billions of light-years away.

Scientists at the Event Horizon Telescope (EHT) have imaged the distant blazar J1924-2914 with unprecedented angular resolution. The image unveiled a helically bent jet originating from a compact quasar core.

A study of the source across different angular scales was enabled by nearly simultaneous observations across the radio frequency band – the EHT, operating at 230 GHz, the Global Millimeter VLBI Array, operating at 86 GHz, and the Very Long Baseline Array operating at 2.3 and 8.7 GHz.

Sara Issaoun, NHFP Einstein Fellow at the Harvard & Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead of this study, said, “Our images constitute the highest angular resolution images of polarized emission from a quasar ever obtained. We see interesting details in the strongly polarized innermost core of the source; the polarized emission’s morphology hints at the presence of a twisted magnetic field structure.”

The recently reported EHT observations of Sagittarius A*, the supermassive black hole at the center of our galaxy, required a thorough understanding of the emission in J1924-2914.

Maciek Wielgus, a scientist at the Max Planck Institute for Radio Astronomy in Bonn, Germany, co-leading this study, said“J1924-2914 is our main calibrator for the Sagittarius A* studies – this means that we needed to understand it well so that we could use this knowledge to improve the total intensity and polarimetric calibration of the more difficult, time-variable source that is Sagittarius A*.”

Journal Reference:

  1. S. Issaoun, M. Wielgus, et al. +EHTC: “Resolving the inner parsec of the blazar J1924–2914 with the Event Horizon Telescope”, in Astrophysical Journal 934:145 (2022). DOI: 10.3847/1538-4357/ac7a40
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