# Mass-to-light PyCASSO database

This is a subsection of the PyCASSO value-added catalogue of stellar population properties for CALIFA galaxies.

We provide mass-to-light results derived from the spatially-resolved star formation history of a sample of 452 galaxies observed with integral field spectroscopy in the CALIFA survey.

The spectra were analysed using STARLIGHT. The SSP bases used were Charlot & Bruzual 2007 (CBe). The suffix "zca6e" refers to the base CBe. This work used COMBO data from the CALIFA Survey DR3.

The catalogue provides maps for the stellar mass density and luminosities, as well as mass-to-light profiles and mass-to-light vs color relations (MLCRs) stacked by morphology.

For a full description of the sample and analysis, download the article.

F i l t e r s

Luminosites, magnitudes, and colors have been computed for SDSS ugriz and Johnson BVR bands.

SDSS filters appear as lower case in the name of the variables, while Johnson bands are rendered in upper case.

SDSS filters are calculated in the AB system while Johnson bands are given in the Vega system.

V a r i a b l e N a m e s

There are several prefixes and suffixes included in the names of the variables. Here we give a brief explanation of their meaning:

Term Meaning
SynR Luminosities, magnitudes, and colors calculated in the synthetic restframe spectra
SynRD Luminosities, magnitudes, and colors calculated in the dereddened synthetic restframe spectra (using STARLIGHT extinction)
__yx 2D map
ML Mass-to-light
stdn_ Uncertainty band (for the radial profiles)

Masses are given in solar masses units and luminosities in solar luminosities (in the corresponding filter).

The capital letter "R" means that the luminosities (magnitudes and colors) have been computed in the restframe spectra.

The capital letter "D" means that the luminosities (magnitudes and colors) have been computed in the dereddened spectra (using extinction provided by the STARLIGHT fitting).

Examples:

• SynRD_L_u__yx : 2D map of the luminosity in SDSS u-band calculated in the dereddened restframe synthetic spectra
• SynR_ML_B__r : Mass-to-light radial profile obtained where the luminosity has been computed in the restframe synthetic spectra using Johnson B-band

Both, M/L profiles and MLCRs, are provided using SynR (Restframe reddened Synthetic spectra) and SynRD (Restframe Dereddened Synthetic spectra). The SynRD tables may be useful for comparison with models or simulations, while observers might want to use SynR tables.

M a p s

We provide 2D maps of the masses and luminosities (in all filters) for each galaxy.

These are available as a single multi-extension FITS table. Each HDU correspond to a binary table of a particular galaxy. The name of the HDU corresponds to its CALIFA ID (KXXXX).

Note: The header of the PrimaryHDU has a keyword named "SUNLUM" containing a dictionary with the luminosity (ergs/s) of the Sun in each filter.

S t a c k i n g

For computing the radial profiles and MLCRs, the sample has been stacked in three different ways:

Name Description
AVTABLE All galaxies of the sample
HUBTYPE Galaxies stacked by morphology in 7 bins:
E - S0 - Sa - Sb - Sbc - Sc - Sd
HUB3 Galaxies stacked in 3 bins:
Early (E, S0, Sa) - Intermediate (Sb, Sbc) - Late (Sc, Sd)

P r o f i l e s

Stacked radial profiles are computed in steps of 0.1 HLR from 0 to 2.5 HLR. The multi-extension FITS table contains 3 BinTableHDUs, one for each stacked way (AVTABLE, HUBTYP, HUB3).

M L C R s

Mass-to-light vs color relations (MLCRs) have been computed following: $$\log {M/L_{\lambda_i}} = a_{\lambda_i} + b_{\lambda_i} \times (m_{\lambda_j} - m_{\lambda_k})$$ where the bands $\lambda_i$, $\lambda_j$, and $\lambda_k$ may be independent, or $\lambda_i$ = $\lambda_j$ or $\lambda_k$

The multi-extension FITS table contains 3 BinTableHDUs, one for each stacked way (AVTABLE, HUBTYP, HUB3):

Each table contains the following columns:

Column Description
color The color in the right side of equation [1]
filter The filter used for the luminosity in M/L (left side of equation [1])
galaxy Type of galaxy according to the stacking way
AVTABLE: All
HUBTYPE: E, S0, Sa, Sb, Sbc, Sc, Sd
HUB3: Early, Intermediate, Late
mode Spetra used for the computation of luminosities, magnitudes and colors: SynR, SynRD
b Slope of the MLCRs in equation [1]
eb Formal error in the computation of the slope of the MLCRs in equation [1]
a Intercerpt or zero-point of the MLCRs in equation [1]
ea Formal error of the intercerpt of the MLCRs in equation [1]
std Scatter of the residuals of the MLCR ($\sigma_{\lambda}$ in the paper)

R e f e r e n c e

Spatially-resolved mass-to-light from the CALIFA survey. Mass-to-light ratio vs. color relations. R. García-Benito, R. M. González Delgado, E. Pérez, R. Cid Fernandes, S.F. Sánchez, A.L. de Amorim. Astronomy & Astrophysics (2018) [ADS]