# Stellar populations of nine passive spiral galaxies from the CALIFA survey: are they progenitors of S0s?

## TL;DR

This study examines the stellar populations of nine passive spiral galaxies from the CALIFA survey, finding they share similarities with S0 galaxies and may represent an evolutionary stage or pathway toward S0 formation.

## Contribution

It provides detailed stellar population analysis of passive spirals and compares them with S0s, suggesting passive spirals could be progenitors of S0 galaxies based on their stellar properties.

## Key findings

- Passive spirals have diverse stellar populations with no common trend.
- Their properties are encompassed within the spread of S0 galaxy populations.
- Passive spirals tend to have higher metallicity, younger ages, and lower [a/Fe] compared to S0s.

## Abstract

We investigate the stellar population properties of passive spiral galaxies in the CALIFA survey. Nine spiral galaxies that have NUV-r > 5 and no/weak nebular emission lines in their spectra are selected as passive spirals. Our passive spirals lie in the redshift range of 0.001 < z < 0.021 and have stellar mass range of 10.2 < log(M_{\star}/M_{\odot}) < 10.8. They clearly lie in the domain of early-type galaxies in the WISE IR color-color diagram. We analyze the stellar populations out to two effective radius, using the best-fitting model to the measured absorption line-strength indices in the Lick/IDS system. We find that stellar populations of the passive spirals span a wide range, even in their centers, and hardly show any common trend amongst themselves either. We compare the passive spirals with S0s selected in the same mass range. S0s cover a wide range in age, metallicity, and [a/Fe], and stellar populations of the passive spirals are encompassed in the spread of the S0 properties. However, the distribution of passive spirals are skewed toward higher values of metallicity, lower [a/Fe], and younger ages at all radii. These results show that passive spirals are possibly related to S0s in their stellar populations. We infer that the diversity in the stellar populations of S0s may result from different evolutionary pathways of S0 formation, and passive spirals may be one of the possible channels.