"formation_redshift" means two different things when used or not in combination with "max_stellar_age". When max_stellar_age is not set, formation_redshift means the redshift at which the first stars formed. When max_stellar_age is set, formation_redshift can be set to specify a "maximum" formation redshift, in such a way that values of max_stellar_age larger than the age of the Universe are not allowed.
When building a mock catalog, one should use either redshift and formation_redshift or redshift and max_stellar_age to sample SEDs at different evolutionary stages.
When fitting a galaxy, instead, it may be useful to provide a ceiling to max_stellar_age (used as an adjustable parameter), by fixing the formation_redshift (as a fixed parameter) to a given value. Beagle will then check whether the condition max_stellar_age < LookBackTime(formation_redshift) - LBT(redshift) is met.
This is currently not described in the manual. Also, it would probably be useful to introduce two distinct parameter keywords (formation_redshift and max_formation_redshift) to be used in these different occurrences.
"formation_redshift" means two different things when used or not in combination with "max_stellar_age". When max_stellar_age is not set, formation_redshift means the redshift at which the first stars formed. When max_stellar_age is set, formation_redshift can be set to specify a "maximum" formation redshift, in such a way that values of max_stellar_age larger than the age of the Universe are not allowed.
When building a mock catalog, one should use either redshift and formation_redshift or redshift and max_stellar_age to sample SEDs at different evolutionary stages.
When fitting a galaxy, instead, it may be useful to provide a ceiling to max_stellar_age (used as an adjustable parameter), by fixing the formation_redshift (as a fixed parameter) to a given value. Beagle will then check whether the condition max_stellar_age < LookBackTime(formation_redshift) - LBT(redshift) is met.
This is currently not described in the manual. Also, it would probably be useful to introduce two distinct parameter keywords (formation_redshift and max_formation_redshift) to be used in these different occurrences.