MaNGA Firefly value-added catalog
FIREFLY is a full spectral fitting galaxy properties described in this page. There are two Value Added catalogs related to the FIREFLY code: a MANGA VAC and an eBOSS VAC). This page describes the MANGA VAC.
- MANGA firefly SAS folder containing:
- manga_firefly-v2_4_3.fits - full catalogue, downloadable fits-format file, ~6.9 GB
- manga-firefly-v2_4_3-GLOBALPROP.fits - minimal data table only including global properties and gradients (HDU1-3), downloadable fits-format file, ~1 MB
- manga-firefly-v2_4_3-STELLARPOP.fits - medium sized data table only including maps of stellar population parameters (HDU1-13), downloadable fits-format file, ~2.5 GB
- manga-firefly-v2_4_3-INDICES.fits - large data table only including maps of stellar absorption indices (HDU1-6, 14-41), downloadable fits-format file, ~4.7 GB
- MANGA FIREFLY VAC datamodel
- mangaFirefly CAS Table
Basic Galaxy Properties (HDU1)
Other basic galaxy information used in the MaNGA VAC, e.g. the effective radii (Re) values, the axis ratios and position angles used to assign Re fractions to x- and y-positions on the sky are adopted from the NSA catalogue and are available through the MaNGA DRPall file. The kinematics (stellar velocities and velocity dispersions) used to derive the properties in this VAC are available from the MaNGA Data Analysis Pipeline (DAP).
Global Properties (HDU2)
Gradient Properties (HDU3)
Spatially Resolved Quantities (HDU4-41)
The 2-dimensional maps are created by the MaNGA DAP (Westfall et al, in preparation) through Voronoi binning using the algorithm of Cappellari & Copin 2003. Individual MaNGA spectra for each galaxy were binned to create cells with a minimum signal-to-noise ratio of 10 per pixel. This threshold was chosen as the optimum compromise between quality of the spectra and spatial resolution (Goddard et al. 2017).
Spatial information (HDU4, HDU5, HDU13):
The bin number, x position (arcsec), y position (arcsec) and radius (in Re) of each cell of the 2-dimensional maps are provided in HDU4. The geometry of the IFU is given in HDU5. The corresponding S/N ratios (per pixel within r-band) are in HDU13.
Stellar population parameters (HDU6-12):
The light-weighted and mass-weighted stellar ages (log age/Gyr) and metallicities (dex), E(B-V) (mag), mass (log M/Msun) and surface mass density (log M/Msun/kpc2) with associated errors for each spatial bin are provided in HDU6-12.
Absorption line-strengths (HDU14-41):
Measurements of the 25 Lick absorption-line indices (Trager et al. 1998; Worthey & Ottaviani 1997), as well as CaHK (Serven, Worthey & Briley 2005) and D4000, Dn4000 (Bruzual 1983; Balogh et al. 1999) are included. Errors on the measurements were obtained through Monte Carlo simulations. The features are measured on rest-frame, emission-line free spectra produced by the MaNGA DAP. The emission line spectra are determined by the DAP (Westfall et al, in preparation) using an adapted version of the pPXF code of Cappellari & Emsellem 2004. The absorption index measurements provided in this VAC were then corrected for velocity dispersion broadening (adopted from the DAP). The effect was determined on best-fit model spectra. The measurement is therefore provided at the spectral resolution of the MaNGA spectra. The correction factor is provided in addition, so that the original, uncorrected measurement can be reconstructed by dividing the catalogue value by the correction factor. The correction is multiplicative for all indices except for the higher-order Balmer indices (Hgamma, Hdelta) where it is additive. The correction is negligible for the bandhead indices (D4000, Dn4000, CN1, CN2, Mg2, TiO1, TiO2). This information is provided in HDU13-40.
FIREFLY spectral fitter
Rest-framed, emission-line free spectra and velocity dispersions are needed as input to the FIREFLY code. Both the kinematics (velocities and velocity dispersions) and the emission-line spectra are determined by the DAP (Westfall et al., in preparation) using an adapted version of the pPXF code by Cappellari & Emsellem 2004.
Each spectrum was then fit with FIREFLY over the wavelength range 3600-7500A, with a grid of metallicities spanning -2.3 < [Z/H] < 0.3 and ages spanning 0.0065 < Age(Gyr) < 15.0. Example fits to binned spectra and stellar populations maps are shown below:
Note: For technical details regarding the code, see the aforementioned papers. The source code is available through the SDSS svn. There is a publicly available Firefly fitter (v1_1_0) code which depends on a set of publicly available stellar population (v1_0_2) models.
Python plotting script
Other Related References
Westfall et al. in preparation
- Daniel Thomas
- Jianhui Lian
- Claudia Maraston
- Taniya Parikh
- Daniel Goddard
- Kyle Westfall
- Johan Comparat
- Sofia Meneses-Goytia
- Violeta Gonzalez-Perez