research
Cygnus X-1 Needed Two Comptonizing Coronae
A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.
Summary
A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.
An analysis of 2016–2019 AstroSat spectra found that a single Comptonization component, thermal disk and iron line fit Cygnus X-1’s soft states poorly and implied disk radii below one gravitational radius. Adding a relativistic disk required unusually high color factors. A dual model with hot, optically thin and warm, optically thick coronae produced consistent fits across hard, intermediate and soft states. The interpretation is model-dependent but strengthens the case for more than one Comptonizing region.
Why it matters
A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.
Limits and context
No additional limitation was separately recorded.
Key claims
A single-corona fit produced unphysical soft-state disk radii; hot and warm components fit AstroSat observations across states.
Evidence: source-2026-09-14-019
Sources
- arXiv preprint 2609.12072arXiv · primary research
Corrections
No corrections have been recorded for this story.