CosmologyObject

class rubin_sim.phot_utils.CosmologyObject(h0=73.0, om0=0.25, ok0=None, w0=None, wa=None)

Bases: object

Methods Summary

H([redshift])	return the Hubble Parameter in km/s/Mpc at the specified redshift
angular_diameter_distance([redshift])	angular diameter distance to the specified redshift in Mpc
comoving_distance([redshift])	return the comoving distance to the specified redshift in Mpc
distance_modulus([redshift])	distance modulus to the specified redshift
get_current()	Return the cosmology currently stored as the current cosmology
luminosity_distance([redshift])	the luminosity distance to the specified redshift in Mpc
omega_curvature([redshift])	return the effective curvature density Parameter (fraction of critical density) at the specified redshift.
omega_dark_energy([redshift])	return the dark energy density Parameter (fraction of critical density) at the specified redshift
omega_matter([redshift])	return the matter density Parameter (fraction of critical density) at the specified redshift
omega_neutrinos([redshift])	return the neutrino density Parameter (fraction of critical density) at the specified redshift
omega_photons([redshift])	return the photon density Parameter (fraction of critical density) at the specified redshift
set_current(universe)	Take the cosmology indicated by 'universe' and set it as the current/default cosmology (depending on the API of the version of astropy being run)
set_units()	This method specifies the units in which various outputs from the wrapper are expected (this is because the latest version of astropy.cosmology outputs quantities such as the Hubble parameter and luminosity distance with units attached; the version of astropy.cosmology that comes within anaconda does not do this as of 30 October 2014)
w([redshift])	return the dark energy equation of state at the specified redshift

Methods Documentation

H(redshift=0.0)

return the Hubble Parameter in km/s/Mpc at the specified redshift

effectively wrapps astropy.cosmology.FLRW.H()

angular_diameter_distance(redshift=0.0)

angular diameter distance to the specified redshift in Mpc

effectively wraps astropy.cosmology.FLRW.angular_diameter_distance()

comoving_distance(redshift=0.0)

return the comoving distance to the specified redshift in Mpc

note, this comoving distance is X in the FRW metric

ds^2 = -c^2 dt^2 + a^2 dX^2 + a^2 sin^2(X) dOmega^2

i.e. the curvature of the universe is folded into the sin()/sinh() function. This distande just integrates dX = c dt/a

effectively wraps astropy.cosmology.FLRW.comoving_distance()

distance_modulus(redshift=0.0)

distance modulus to the specified redshift

effectively wraps astropy.cosmology.FLRW.distmod()

get_current()

Return the cosmology currently stored as the current cosmology

This is for users who want direct access to all of astropy.cosmology’s methods, not just those wrapped by this class.

documentation for astropy.cosmology can be found at the URL below (be sure to check which version of astropy you are running; as of 30 October 2014, the anaconda distributed with the stack comes with version 0.2.5)

https://astropy.readthedocs.org/en/v0.2.5/cosmology/index.html

luminosity_distance(redshift=0.0)

the luminosity distance to the specified redshift in Mpc

accounts for spatial curvature

effectively wraps astropy.cosmology.FLRW.luminosity_distance()

omega_curvature(redshift=0.0)

return the effective curvature density Parameter (fraction of critical density) at the specified redshift.

Positive means the universe is open.

Negative means teh universe is closed.

Zero means the universe is flat.

effectively wraps astropy.cosmology.FLRW.Ok()

omega_dark_energy(redshift=0.0)

return the dark energy density Parameter (fraction of critical density) at the specified redshift

effectively wraps astropy.cosmology.FLRW.Ode()

omega_matter(redshift=0.0)

return the matter density Parameter (fraction of critical density) at the specified redshift

effectively wraps astropy.cosmology.FLRW.Om()

omega_neutrinos(redshift=0.0)

return the neutrino density Parameter (fraction of critical density) at the specified redshift

assumes neutrinos are massless

effectively wraps astropy.cosmology.FLRW.Onu()

omega_photons(redshift=0.0)

return the photon density Parameter (fraction of critical density) at the specified redshift

effectively wraps astropy.cosmology.FLRW.Ogamma()

set_current(universe)

Take the cosmology indicated by ‘universe’ and set it as the current/default cosmology (depending on the API of the version of astropy being run)

universe is also assigned to self.active_cosmology, which is the cosmology that this wrapper’s methods use for calculations.

set_units()

This method specifies the units in which various outputs from the wrapper are expected (this is because the latest version of astropy.cosmology outputs quantities such as the Hubble parameter and luminosity distance with units attached; the version of astropy.cosmology that comes within anaconda does not do this as of 30 October 2014)

w(redshift=0.0)

return the dark energy equation of state at the specified redshift

effecitvely wraps astropy.cosmology.FLRW.w()