Black Holes Expert

---
name: black-holes-expert
version: 1.0.0
description: Expert-level black hole physics covering formation, spacetime structure, accretion disks, jets, Hawking radiation, gravitational waves from mergers, and observational evidence.
author: luo-kai
tags: [black holes, general relativity, accretion, gravitational waves, Hawking radiation]
---

# Black Holes Expert

## Before Starting
1. Stellar mass, intermediate, or supermassive black hole?
2. Classical GR or quantum effects focus?
3. Theory or observations?

## Core Expertise Areas

### Black Hole Spacetime
Schwarzschild metric: non-rotating black hole, event horizon at r equals 2GM over c squared.
Kerr metric: rotating black hole, ergosphere, frame dragging.
Event horizon: one-way membrane, nothing escapes once inside.
Singularity: point of infinite density, classical GR breaks down here.
Photon sphere: unstable circular photon orbits at r equals 3GM over c squared.

### Accretion and Jets
Accretion disk: infalling matter forms disk, releases gravitational energy as radiation.
ISCO: innermost stable circular orbit, r equals 6GM over c squared for Schwarzschild.
Eddington luminosity: maximum luminosity before radiation pressure halts accretion.
Relativistic jets: collimated outflows, powered by spin energy via Blandford-Znajek mechanism.
Thin disk vs ADAF: radiatively efficient vs inefficient accretion modes.

### Hawking Radiation
Virtual pairs near horizon: one falls in, one escapes, black hole radiates thermally.
Hawking temperature: inversely proportional to mass, smaller black holes are hotter.
Black hole evaporation: mass loss over astronomical timescales for stellar mass BHs.
Information paradox: unitarity vs Hawking radiation, unresolved fundamental problem.

### Observations
Gravitational waves: LIGO and Virgo BH mergers, chirp signal, mass measurement.
EHT: Event Horizon Telescope imaged M87 and Sgr A star shadows.
X-ray binaries: Cygnus X-1, first stellar BH candidate, accretion disk emission.
Stellar orbits: S-stars orbiting Sgr A star, mass of 4 million solar masses confirmed.

## Best Practices
- Specify black hole mass and spin when describing properties
- Use GR not Newtonian gravity near the horizon
- Distinguish event horizon from apparent horizon in dynamical spacetimes
- Check observational claims against multiple independent evidence

## Common Pitfalls
| Pitfall | Fix |
|---|---|
| Thinking of BH as vacuum cleaner | Only captures matter within gravitational influence |
| Confusing Schwarzschild and Kerr | Realistic BHs rotate, Kerr is more physical |
| Ignoring spin in accretion efficiency | Maximally spinning BHs are more efficient |
| Misinterpreting EHT images | Shadow size relates to photon ring not event horizon directly |

## Related Skills
- physics/general-relativity-expert
- astrophysics-expert
- physics/particle-physics-expert