Description
Combine supplied cosmological and peculiar redshift factors.
Cosmology uses several distance measures and often expresses the expansion rate in mixed astronomical units. Scale-factor relations, inverse-Hubble scales and relativistic velocity composition answer different questions; units and the distinction between local algebra and an integrated expansion history are essential.
Combine supplied cosmological and peculiar redshift factors.
When to use this tool
Use Cosmological Redshift Peculiar Log Factor Split when checking one explicit cosmological distance, redshift-factor or unit convention.
How to use the tool and how it works
- Enter cosmologicalRedshift, peculiarRedshift. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read combinedRedshift, logCosmologicalFactor, logPeculiarFactor. Use the output convention below.
Combine supplied cosmological and peculiar redshift factors. Require both redshifts > -1; combinedRedshift = (1+zc)*(1+zp)-1 and the two log factors use ln(1+z).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| cosmologicalRedshift | Cosmological Redshift | Required. Finite number; strictly above -1. |
| peculiarRedshift | Peculiar Redshift | Required. Finite number; strictly above -1. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| combinedRedshift | Combined Redshift | Required. Finite number. |
| logCosmologicalFactor | Log Cosmological Factor | Required. Finite number. |
| logPeculiarFactor | Log Peculiar Factor | Required. Finite number. |
{
"input": {
"cosmologicalRedshift": 1,
"peculiarRedshift": 0.1
},
"output": {
"combinedRedshift": 1.2000000000000002,
"logCosmologicalFactor": 0.6931471805599453,
"logPeculiarFactor": 0.09531017980432487
}
}Limitations and assumptions
- This is supplied factor composition; no peculiar velocity, gravitational contribution or cosmological decomposition is estimated.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use a complete cosmological distance/time calculation and the appropriate observation model when an actual source distance, age or velocity is required.
References
Similar or alternative tools
- Redshift Velocity Composition Gap
Compose two collinear special-relativistic velocity fractions.
- Cosmic Scale Factor Reference Gap Tool
Convert a supplied redshift using an explicit scale-factor normalization; no cosmological parameters or distances.