Nebular Emission Line Analysis

Methods related to nebular line analysis, e.g. dust extinction, SFR

frb.galaxies.nebular.calc_dust_extinct(neb_lines, method)[source]

Estimate the Visual extinction A_V based on input nebular emission lines

Uses the Gordon 2024

Args:

  • neb_lines (dict) – Line fluxes

  • method (str) – Name of the method Ha/Hb – Use the Halpha/Hbeta ratio and standard intrinsic flux

  • curve (str) – Extinction curve to use

Returns:

A_V in magnitudes

Return type:

float

frb.galaxies.nebular.calc_logOH(neb_lines, method)[source]

Estimate the oxygen abundance based on the input nebular emission line fluxes For now based on the O3N2 calibration from https://ui.adsabs.harvard.edu/abs/2018AJ….155…82H/abstract

Args:

  • neb_lines (dict) – Line fluxes

  • method (str) – Name of the method O3N2 – Use the O3N2 calibration from Hirschauer+18

Returns:

12+log(O/H), sigma+, sigma-

Return type:

tuple

frb.galaxies.nebular.calc_lum(neb_lines, line, z, cosmo, AV=None)[source]

Calculate the line luminosity (and error) from input nebular line emission

Error is -999.*erg/s if input line flux has negative error

Args:

  • neb_lines (dict) – Observed line fluxes and errors

  • line (str) – Line to analyze

  • z (float) – Emission redshift – for Luminosity distance

  • cosmo (astropy.cosmology.FLRW) – Cosmology

  • AV (float, optional) – Visual extinction, if supplied will apply

Returns:

Luminosity, sig(Luminosity)

Return type:

Quantity, Quantity

frb.galaxies.nebular.calc_SFR(neb_lines, method, z, cosmo, AV=None, curve='MW')[source]

Calculate the SFR from input nebular line emission

Args:

  • neb_lines (dict) – Observed line fluxes

  • method (str) – Method for deriving the SFR Ha – Use the Halpha line flux

  • z (float) – Emission redshift – for Luminosity distance

  • cosmo (astropy.cosmology.FLRW) – Cosmology

  • AV (float, optional) – Visual extinction, if supplied will apply

  • curve (str) – Name of the extinction curve. Only used if A_V is supplied

Returns:

SFR with units of Msun/yr

Return type:

Quantity

frb.galaxies.nebular.get_ebv(coords, definition='SandF', region=<Quantity 5. deg>, get_ext_table=False)[source]

Get the E(B-V) value and statistic from the Milky way dust extinction within the query region around the input coordinate

Args:

  • coords (Astropy SkyCoord) – Input celestial coordinates

  • definition (str, optional) – Can be either “SFD” or “SandF”. They stand for the definitions of E(B-V) according to either Schlegel et al. 1998 (ApJ 500, 525) or Schlafly and Finkbeiner 2011 (ApJ 737, 103) respectively

  • region (Astropy Angle (Quantity), optional) – Angular radius around the input coordinate where the query is run to obtain statistics. Must be between 2 deg and 37.5 deg. Default value: 5 deg.

  • get_stats – bool, optional If true, also returns a dict with the statistics of E(B-V) within the query region.

  • get_ext_table – bool, optional If true, also returns the table with A/E(B-V) ratios for multiple filters.

Returns:

Dict with E(B-V) at refPixelValue, meanValue, std, minValue and maxValue in the query region. All values are in mags.

Return type:

dict