Impact of the nonthermal electron radiation effects on the horizon scale image structure of Sagittarius A*

Abstract

The Event Horizon Telescope (EHT), with $\sim$20 $\mu$as high angular resolution, recently resolved the millimeter image of the suppermassive black hole in the Galaxy, Sagittarius A*. This opens a new window to study the plasma on horizon scales. The accreting disk probably contains a small fraction of nonthermal electrons and their emissions should contribute to the observed image. We study if such contributions are sufficient to cause structural differences detectable by current and future observational capabilities. We introduce nonthermal electrons in a semi-analytical accretion disk, which considers viscosity-leading heating processes, and adopt a continued hybrid electron energy distribution of thermal distribution and power-law tail. We generate the black hole images and extract the structural features as crescent parameters. We find the existence of nonthermal electron radiation makes the crescent much brighter, slightly larger, moderately thicker, and much more symmetric. When the nonthermal connecting Lorentz factor ${\gamma }_c=65$, which is equivalent to the nonthermal electrons accounting for $\sim 1.5$% of the totals, nonthermal effects cause $\sim 2$% size difference at 230 GHz. Comparing with the structural changes caused by other physical factors, including inclination between the system and the observer, black hole spin, and interstellar medium scattering effects, we find that although nonthermal electron radiation takes the most unimportant role at 230 GHz, it becomes more significant at 345 GHz.

References in corpus (23)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole
• First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole
• First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• First M87 Event Horizon Telescope Results. III. Data Processing and Calibration
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• Numerical Simulation of Hot Accretion Flows (III): Revisiting wind properties using trajectory approach
• Observing the Inner Shadow of a Black Hole: A Direct View of the Event Horizon
• Simulating the Emission and Outflows from Accretion Disks
• The Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Evaluation of New Submillimeter VLBI Sites for the Event Horizon Telescope
• Simulations of imaging the event horizon of Sagittarius A* from space
• Comparison of the ion-to-electron temperature ratio prescription: GRMHD simulations with electron thermodynamics
• The Effects of Accretion Flow Dynamics on the Black Hole Shadow of Sagittarius A${}^{\ast }$
• Stochastic Optics: A Scattering Mitigation Framework for Radio Interferometric Imaging
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*

Cited by in corpus (1)

• Deep learning inference with the Event Horizon Telescope II. The Zingularity framework for Bayesian artificial neural networks