Emission-line Moments
Analysis class: EmissionLineMoments
Method definition: EmissionLineMomentsDef
Reference root: $MANGA_SPECTRO_ANALYSIS/$MANGADRP_VER/$MANGADAP_VER/[PLATE]/[IFUDESIGN]/ref
Reference file:
Before Gaussian emission-line modeling:
manga-[PLATE]-[IFUDESIGN]-[DRPQA_KEY]-[BIN_KEY]-[CONTINUUM_KEY]-[ELMOM_KEY].fits.gz
After Gaussian emission-line modeling:
manga-[PLATE]-[IFUDESIGN]-[DRPQA_KEY]-[BIN_KEY]-[CONTINUUM_KEY]-[ELFIT_KEY]-[ELMOM_KEY].fits.gz
Config files: $MANGADAP_DIR/mangadap/config/emission_line_moments
Example config: emomm.ini
[default]
key = EMOMMPL9
minimum_snr = 0.0
artifact_mask = BADSKY
emission_passbands = ELBMPL9
redo_postmodeling = True
fit_vel_name = Ha-6564
Important class dependencies:
mangadap.proc.bandpassfilter
: Provides the core functions that perform the bandpass integrals.
EmissionMomentsDB
: Generalized class that provides the detailed parameters for a set of emission-line windows used to perform non-parametric moments.
EmissionLineFit
: Provides functions common to both the moment and Gaussian-fit calculations.
SpectralPixelMask
: Used to mask spectral regions.
Algorithm:
Read the artifact database to setup the
SpectralPixelMask
object based on theartifact_mask
config.Set up the
EmissionMomentsDB
using theemission_passbands
config.Determine the binned spectra above the S/N limit set by the
minimum_snr
config.Use the
StellarContinuumModel
object to construct the stellar continuum for each binned spectrum.Subtract the continuum using
subtract_continuum()
. WARNING: If a binned spectrum does not have a fitted stellar continuum, the moment analysis is performed on the binned spectrum without any continuum subtraction.Measure the moments using
measure_moments()
.
Redshift the emission-line passbands based on the provided redshift.
Determine the pseudo-continuum in the red and blue bands using
pseudocontinuum()
.Set the slope and intercept of a linear continuum extrapolation between the two sidebands for all emission-lines.
For each emission line, measure the first 3 moments of the pseudo-continuum-subtracted spectra using
single_band_moments()
: (0) integrated flux; (1) intensity weighted redshift (\(cz\)); and (2) intensity weighted \((cz)^2\).Determine the instrumental dispersion at the 1st moment locations of each line using
instrumental_dispersion()
.Flag any measurement without a continuum spectrum as
NOCORRECTION
.If any of the passbands (blue, red, main) are incomplete (or empty) due to masked pixels or straddle the jump between where there is and is not a viable continuum subtracted, or if that jump occurs between the blue and red passbands, flag the moments as
FITFAILED
in theMAPS
file.Mask any “dummy” bands. Dummy bands are used to ensure that the emission-line moment channels match the emission-line Gaussian-fit channels in the output
MAPS
file.Using the 0th moment (integrated flux) and the binned spectra (‘’without’’ continuum subtraction), measure the emission-line equivalent widths using
emission_line_equivalent_width()
.Construct emission-line-moments
BINID
map. Bin IDs are the same as for the binned spectra except that any bin that does not meet the S/N limit are given a emission-line-moment bin ID of -1.