rail.creation.degradation.spectroscopic_degraders module

Degraders that emulate spectroscopic effects on photometry

class rail.creation.degradation.spectroscopic_degraders.InvRedshiftIncompleteness(args, comm=None)

Bases: Degrader

Degrader that simulates incompleteness with a selection function inversely proportional to redshift.

The survival probability of this selection function is p(z) = min(1, z_p/z), where z_p is the pivot redshift.

Parameters:

pivot_redshift (positive float) – The redshift at which the incompleteness begins.

config_options = {'output_mode': <ceci.config.StageParameter object>, 'pivot_redshift': <class 'float'>, 'seed': 12345}

name = 'InvRedshiftIncompleteness'

run()

Run method

Applies incompleteness

Notes

Get the input data from the data store under this stages ‘input’ tag Puts the data into the data store under this stages ‘output’ tag

class rail.creation.degradation.spectroscopic_degraders.LineConfusion(args, comm=None)

Bases: Degrader

Degrader that simulates emission line confusion.

Example: degrader = LineConfusion(true_wavelen=3727,
                                  wrong_wavelen=5007,
                                  frac_wrong=0.05)

is a degrader that misidentifies 5% of OII lines (at 3727 angstroms) as OIII lines (at 5007 angstroms), which results in a larger spectroscopic redshift.

Note that when selecting the galaxies for which the lines are confused, the degrader ignores galaxies for which this line confusion would result in a negative redshift, which can occur for low redshift galaxies when wrong_wavelen < true_wavelen.

Parameters:

• true_wavelen (positive float) – The wavelength of the true emission line. Wavelength unit assumed to be the same as wrong_wavelen.

• wrong_wavelen (positive float) – The wavelength of the wrong emission line, which is being confused for the correct emission line. Wavelength unit assumed to be the same as true_wavelen.

• frac_wrong (float between zero and one) – The fraction of galaxies with confused emission lines.

config_options = {'frac_wrong': <class 'float'>, 'output_mode': <ceci.config.StageParameter object>, 'seed': 12345, 'true_wavelen': <class 'float'>, 'wrong_wavelen': <class 'float'>}

name = 'LineConfusion'

run()

Run method

Applies line confusion

Notes

Get the input data from the data store under this stages ‘input’ tag Puts the data into the data store under this stages ‘output’ tag