Description
Calculate a supplied observed-minus-modeled redshift residual.
Cosmological quantities depend on scale factor, redshift, distance definition and the dimensionless Hubble parameter h. Proper and comoving distances differ at a specified epoch, and h-scaled units differ from the dimensional Hubble constant. A scalar rescaling or model contribution preserves supplied conventions without fitting a cosmology or inferring an observed distance.
Calculate a supplied observed-minus-modeled redshift residual.
When to use this tool
Use Redshift Observation Vs Model Residual when you already have observedRedshift, modeledRedshift and need to calculate a supplied observed-minus-modeled redshift residual.
How to use the tool and how it works
- Enter observedRedshift, modeledRedshift. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read residual. Use the output convention below.
Require each redshift>-1; subtract model from observation.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| observedRedshift | Observed Redshift | Required. Finite number; strictly above -1. |
| modeledRedshift | Modeled Redshift | Required. Finite number; strictly above -1. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| residual | Residual | Required. Finite number. |
{
"input": {
"observedRedshift": 1.2,
"modeledRedshift": 1.1
},
"output": {
"residual": 0.09999999999999987
}
}Limitations and assumptions
- Signed residuals and negative redshifts above -1 are accepted. No redshift, uncertainty, velocity, model likelihood or fit 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 the complete cosmological model and its parameter, epoch and unit definitions for a physical inference. Review redshift, distance, lensing and spectrum conventions before combining these local terms; they do not perform line-of-sight integration, parameter estimation or uncertainty analysis.
References
Similar or alternative tools
- Source Redshift Behind Lens Flag
Compare supplied nonnegative source and lens redshifts.
- Redshift Velocity Small Offset Convention
Calculate a small-redshift-offset velocity approximation under supplied conventions.