uvex_transients.utils.cosmology.angular_to_physical#

uvex_transients.utils.cosmology.angular_to_physical(theta: Quantity, redshift: float | NDArray[float64] | None = None, cosmology: Cosmology | None = None) → Quantity[source]#

Convert an angular size to a physical transverse size.

Parameters:

  • theta (~astropy.units.Quantity) – Angular size (e.g., arcsec or radians).

  • redshift (float) – Redshift of the object.

  • cosmology (~astropy.cosmology.FLRW, optional) – Cosmology used to compute the angular diameter distance. If None, the configured default cosmology is used.

Returns:

Physical transverse size corresponding to the angular extent.

Return type:

~astropy.units.Quantity

Notes

The physical transverse size is given by

\[s = \theta \, D_A\]

where \(D_A\) is the angular diameter distance.

Examples

>>> import astropy.units as u
>>> angular_to_physical(1 * u.arcsec, redshift=1.0)
<Quantity 8.23125024 kpc>