Prior

Gsf calculates posterior probability through an MCMC process, whose concept is based on the Bayes theorem.

For each parameter set in the minimizer, prior is set (posterior_flexible.py). In the current version, prior for most of the parameters (amplitude, metallicity, dust attenuation, redshift) are set flat, so that;

\[\begin{split}prior(\theta) &= 1\ \mathrm{if}\ \theta_\mathrm{min} < \theta < \theta_\mathrm{max} \\ &= 0\ \mathrm{else}.\end{split}\]

Below is the list of parameters and their ranges set in default.

Parameter ranges:

Parameter	Range	Description
A	[AMIN:AMAX]	Amplitude, in logarithmic space. AMIN and AMAX are set to -3 and 3 in default.
Z	[ZMIN:ZMAX]	Metallicity, in logarithmic space.
AV	[AVMIN:AVMAX]	Dust attenuation in V-band, in linear space. AVMIN and AVMAX are set to 0 and 4 in default.
z	[ZGAL-EZL:ZGAL+EZH]	Redshift, in linear space. EZL and EZH are set to 0.3. Can be specified in the configuration file.
AGE (tau-model)	[AGEMIN:AGEMAX]	Age of tau model, in logarithmic space. Range can be specified by AGEMIN and AGEMAX.
TAU (tau-model)	[TAUMIN:TAUMAX]	Age of tau model, in logarithmic space. Range can be specified by TAUMIN and TAUMAX.