# Black Hole Binary (DD-464)

> A supermassive black hole binary forms after two galaxies merge and their central black holes sink toward the middle and orbit each other. They spiral closer through interactions with surrounding stars and gas and, finally, by emitting gravitational waves, before merging into one more massive black hole. The footage, credited to astropodis, shows a simulation of two black holes orbiting.

- Department: Space
- First published: 2025-01-20
- Last updated: 2025-01-20
- Permalink: https://detailenjoyer.com/case/black-hole-binary/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-464-F01**: Galaxy mergers. _(Write-up · Exhibit A (Origin))_
- **DD-464-F02**: Two black holes. _(Write-up · Exhibit B (Orbit))_

## Write-up

When galaxies collide, their central black holes can end up orbiting each other. Gravitational waves drain their energy until they merge.

1. **Origin**: Galaxy mergers.
2. **Orbit**: Two black holes.
3. **Inspiral**: Energy lost.
4. **Waves**: Gravitational waves.
5. **End**: One larger black hole.

## Related case files

- [Neutron Binary (DD-542)](https://detailenjoyer.com/case/neutron-binary/): I linked another binary merger
- [Event Horizon (DD-089)](https://detailenjoyer.com/case/event-horizon/): I linked more black holes

## Reel vs. record

- **Note**: None needed.

## Video: Black Hole Binary: When Galaxies Collide, Their Central Black Holes Can End up Orbiting Each Other

- Duration: 23.0 s · Published: 2025-01-20
- File: https://detailenjoyer.com/assets/videos/DFEn_i9q_y8.mp4

### Transcript

Did you know, binary supermassive black hole systems consist of two supermassive black holes orbiting each other, typically found at the centers of merging galaxies. These systems form when two galaxies collide, bringing their central black holes into close proximity, as the black holes spiral closer due to gravitational interactions, and the loss of energy through the emission of gravitational waves, they eventually merge into a single, even more massive black hole. NOW YOU KNOW!

## Questions & answers

**Q: What forms them?**  
A: Collisions. _(Source: Write-up · Exhibit A (Origin) · Wikipedia: Binary black hole)_

**Q: What carries energy away?**  
A: Ripples. _(Source: Write-up · Exhibit B (Orbit) · Wikipedia: Binary black hole)_

**Q: End result?**  
A: Merger. _(Source: Write-up · Exhibit C (Inspiral) · Wikipedia: Binary black hole)_

**Q: Where found?**  
A: Cores. _(Source: Write-up · Exhibit D (Waves) · Wikipedia: Binary black hole)_

**Q: What do they do first?**  
A: Binary. _(Source: Write-up · Exhibit E (End) · Wikipedia: Binary black hole)_

## Sources

- [Wikipedia: Binary black hole](https://en.wikipedia.org/wiki/Binary_black_hole)

## Cite this case file

Easterling, Marcus. "Black Hole Binary." The Detail Department (DetailEnjoyer), case file DD-464, last updated Jan 20, 2025. https://detailenjoyer.com/case/black-hole-binary/