Gravitational lens geometry and image multiplicity
A thin gravitational lens relates a source's unlensed angular position to observed image positions through a mass-dependent deflection.
Key knowledge
A thin gravitational lens relates a source's unlensed angular position to observed image positions through a mass-dependent deflection. Nonlinearity can produce multiple images. Lens-to-source and observer distances are angular-diameter distances; cosmological lens–source distance is not generally their simple difference.
Values and equations
β = θ − (Dls/Ds) α̂(θ)
- β
- unlensed source angle rad
- θ
- image angle rad
- α̂
- physical deflection angle rad
- Dls
- lens-to-source angular-diameter distance m
- Ds
- observer-to-source angular-diameter distance m
Conditions and scope
- Assumes small angular deflections and a thin lens; strong lensing refers to image multiplicity, not necessarily strong-field gravity.
- Image shapes or positions constrain projected mass through a model and can retain degeneracies.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read scalar geometry θDs=βDs+αDds, angular-diameter distance distinction and multiple-image paragraph; did not reproduce the source's dimensionally incomplete printed mass-inside-ring sentence.
2026-10-10 · Independent AI editorial review: All26 Life-authored Cosmos compact statements, conditions, displayed equations and all56 origin semantic links read. Entire26-entry author statement/source matrix and explicit exclusions assessed. Targeted independent primary sections are listed below; this does not claim every referenced source body or proof was independently re-read. This is scoped AI reference-content review, not human disciplinary certification or whole-field completion. Receipt: cosmos-life-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-cosmos-thin-lens
- Revision
- core.1
- Structured reference record
- University core expansion