Astronomy reading
How accretion disks shine
Begin with two rings pulling on each other. Follow the energy that heats the gas, add radiation from rings at different temperatures, and see how motion and gravity change the light received far away.
L1 · Concept
Why gas around a black hole shines
Orbiting gas gives angular momentum outward and settles inward. The difference in orbital energy heats the disk and powers its radiation.
L2 · Chapter
Where a thin disk heats
Derive a thin disk’s surface flux from torque work, locate its hottest ring and calculate the luminosity of both disk faces.
L2 · Chapter
Adding the spectra of differently heated rings
Add diluted Planck emission from disk annuli, distinguish intensity from flux, and predict how a hotter disk changes its spectrum.
L3 · Chapter
How frequency and brightness change on the way out
Follow one light path from disk to observer, derive the cubic and fourth-power intensity factors, and separate frequency shift from heating.
L3 · Chapter
Which disk surface a light path meets first
Trace a saved path through an inner hole to its first opaque disk encounter, and distinguish known darkness from unresolved critical paths.
L4 · Method and paper reading
Recompute a disk image and spectrum from saved intersections
Follow one frozen disk intersection through thermal emission, a finite image cell and the full spectrum with a portable Python tutorial.
L4 · Method and paper reading
How to read a thin-disk spectrum paper
Read the axes, caption and assumptions of a Kerr disk spectrum figure, then identify the external inputs needed for a spin estimate.