Description
Convert an h-scaled cosmological wavenumber.
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.
Convert an h-scaled cosmological wavenumber.
When to use this tool
Use Cosmological Wavenumber Hunit Crosswalk when checking one explicit cosmological distance, redshift-factor or unit convention.
How to use the tool and how it works
- Enter numericHPerMpc, h. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read perMpc, numericMpcOverHWavelength. Use the output convention below.
Convert an h-scaled cosmological wavenumber. Require positive numericHPerMpc and dimensionless h; perMpc = numericHPerMpc*h, numericMpcOverHWavelength = 2*pi/numericHPerMpc.1
Cosmological distance, volume and lookback-time relations require the appropriate expansion-rate and distance conventions; local factors do not replace integration.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| numericHPerMpc | Numeric HPer Mpc | Required. Finite number; strictly above 0. |
| h | Dimensionless H0/(100 km s^-1 Mpc^-1). | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| perMpc | Angular wavenumber coefficient in inverse Mpc after multiplication by h. | Required. Finite number. |
| numericMpcOverHWavelength | Wavelength numeric coefficient in Mpc/h, using 2*pi/k. | Required. Finite number. |
{
"input": {
"numericHPerMpc": 0.2,
"h": 0.7
},
"output": {
"perMpc": 0.13999999999999999,
"numericMpcOverHWavelength": 31.41592653589793
}
}Limitations and assumptions
- Wavenumber is angular wavenumber; the wavelength's numeric coefficient is expressed in Mpc/h rather than plain Mpc.
- 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
- Cosmological Angle Radian Basis Token
Convert a supplied angular value with an explicit radians-per-unit factor.
- Baryon Density Physical Parameter Crosswalk
Return the physical baryon-density parameter combination.