frb.em - Emission Measure

Emission Measure calculations, including estimating EM from observed Halpha surface brightness.

Module for EM calculations

frb.em.em_from_halpha(sb_obs, z, T=<Quantity 10000. K>)[source]

Estimate EM from the observed Halpha surface brightness

Follows the Reynolds 1977 formalism

Args:

  • sb_obs (Quantity) – Observed surface brightness

  • z (float) – Redshift of the galaxy

  • T (Quantity, optional) – Temperature for the analysis

Returns:

EM

Return type:

Quantity

frb.em.dm_from_em(EM, L, ff=1.0, eps=1.0, cloudcloud=2.0)[source]

This follows the formalism presented in Tendulkar+2017 which follows Reynolds 1977 and Cordes+2016

Args:

  • EM (Quantity) – Emission measure

  • L (Quantity) – Linear size of the source

  • ff (float, optional) – Filling factor

  • eps (float, optional) – fractional variation inside discrete clouds due to turbulent-like density variations

  • cloudcloud (float, optional) – cloud-to-cloud density variations in the ionized region of depth L in kpc.

Returns:

DM at the source; correct for (1+z)^-1 at your liking

Return type:

Quantity