Jul 5 – 10, 2021
Europe/Rome timezone

Event Horizon Telescope Paper VII: imaging the polarized emission around M 87*

Jul 5, 2021, 4:30 PM
20m
Talk in the parallel session Radio Astronomy from Space Radio Astronomy from Space

Speaker

Maciek Wielgus (Black Hole Initiative (Harvard University))

Description

In 2017, the Event Horizon Telescope (EHT) observed the supermassive black hole M 87* at the center of the giant elliptical galaxy Messier 87 using very-long baseline interferometry between a global network of radio telescopes. Operating at a high radio frequency of 230 GHz, EHT enables imaging of the optically thin emission region in the immediate vicinity of the event horizon of M 87*, achieving resolution of ~3 Schwarzschild radii. Recently, the first images of the linearly polarized emission component were published. They indicate that only a part of the M 87* ring is significantly polarized. The resolved fractional linear polarization has a maximum located in the southwest part of the ring, where it rises to the level of ~15%. The polarization position angles are arranged in a nearly azimuthal pattern. Properties of the compact emission were characterized and evidence for the temporal evolution of the polarized source structure over one week of EHT observations was found. I will present the challenges of polarimetric calibration and imaging and strategies to mitigate them with a variety of analysis tools. Then I will discuss the morphology of the polarimetric images of the M 87* and derived quantities characterizing these images, which enabled the theoretical interpretation of these results.

Primary authors

Maciek Wielgus (Black Hole Initiative (Harvard University)) Event Horizon Telescope Collaboration

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