NSA SEDflow Catalog

This probabilistic value-added catalog provides detailed physical properties for 33,884 galaxies in the NASA-Sloan Atlas (http://www.nsatlas.org/). The properties are inferred from optical photometry in the u, g, r, i, z bands using SEDflow, an accelerated Bayesian SED modeling method that combines the Hahn et al. (2022a) PROVABGS SED model with Amortized Neural Posterior Estimation. For more details on this catalog and SEDflow see Hahn & Melchior (2022).

For each galaxy, the catalog provides 10,000 samples drawn from the posteriors of

log_mstar :
    log10 of stellar mass

log_sfr_1gyr :
    log10 of average star formation rate over 1Gyr

log_Z_MW :
    log10 of mass-weighted metallicity

beta1, beta2, beta3, beta4 :
    coefficients of the non-negative matrix factorization (NMF)
    star formation history basis functions

fburst :
    fraction of stellar mass formed by star burst

tburst :
    time of star burst event

log_gamma1, log_gamma2 :
    log10 of coefficients of the NMF metallicity history basis
    functions

tau_bc :
    birth cloud optical depth

tau_ism :
    diffuse dust optical depth

n_dust :
    Calzetti (2001) dust index

For more details on the galaxy properties, see Hahn et al. (2022a).

A small fraction of NSA galaxies have photometry or uncertainties outside of the SEDflow training data. For these galaxies, SEDflow does not produce sensible posteriors. We estimate their posteriors using the PROVABGS SED model with MCMC sampling in the same way as Hahn et al. (2022a). We mark these galaxies using:

sedflow : boolean
    True if posterior was estimated using SEDflow.
    False if posterior was estimated using MCMC

The catalog also includes:

NSAID :
    unique ID within the NSA catalog

mag_u, mag_g, mag_r, mag_i, mag_z :
    u, g, r, i, z optical magnitudes derived from NSA catalog's
    NMGY Galactic-extinction corrected AB photometric flux

sigma_u, sigma_g, sigma_r, sigma_i, sigma_z:
    uncertainties of u, g, r, i, z optical photometry in
    magnitude space

Download

Download the catalog nsa.sedflow.hdf5 at zenodo

The catalog is in hdf5 format and can be read in python using the h5py package

import h5py

f = h5py.File('nsa.sedflow.hdf5', 'r')

# print data columns
print(f.keys())

# read stellar mass
logm = f['log_mstar'][...]

f.close()

Attribution

Please cite Hahn & Melchior (2022) if you use the SEDflow NSA catalog in your research.