Classroom Aid - SMBH Accretion Disk Composition
Channel: David Butler
Date: 2023-11-15

https://howfarawayisit.com
With the James Webb Space Telescope, we can explore the contents of a accretion disk around a super massive black hole.
Here’s a Webb image of Stephan's Quintet. At the center of NGC 7319, there is a supermassive black hole around which the galaxy is rotating. 
This one is ‘active’ meaning significant quantities of material are falling into it. These are referred to as [Seyfert galaxies or] galaxies with an Active Galactic Nucleus (AGN for short). As falling matter approaches the black holes’ event horizon, it becomes very hot and a small percentage of it is pushed away from the black hole in the form of winds and jets just before it would have passed across the event horizon – never to be seen again. 
Webb has on board a medium-resolution spectrometer (MRS) as part of the Mid-Infrared Instrument to analyze the light spectrum of objects like these to determine the chemical makeup of the material falling into the black hole. With this, scientists can measure spatial structures, determine the velocity of those structures, and get a full range of spectral data. This instrument was able to determine the composition of the gas near the supermassive black hole.
Here we are mapping the wavelength that identifies an element against the flux density that tells us the amount of that element present. The spectrum reveals that the supermassive black hole has a reservoir of colder, denser gas with large quantities of molecular hydrogen and silicate dust that absorb the light from the central regions of the galaxy.

The spectrum, from the black hole’s outflow, shows a region filled with hot, ionized gases, including iron, argon, neon, sulphur and oxygen as denoted by the peaks at given wavelengths. The presence of multiple emission lines from the same element with different degrees of ionization is valuable for understanding the properties and origins of the outflow. 

Note the units for ‘brightness’. A jansky is a very small unit – 10-12 watts and Webb is detecting down to 0.001 janskys. Picture a dim 1-watt lightbulb. Webb can detect a wattage that is 0.000000000000001 watts. It’s quite remarkable.