Star formation and AGN activity in the most luminous LINERs in the local universe

TL;DR

This study characterizes the most luminous local LINERs, revealing their properties, star formation rates, and AGN activity, and compares them to other low-redshift LINERs and star-forming galaxies.

Contribution

It provides detailed spectroscopic and FIR analysis of luminous LINERs, confirming their existence locally and exploring their co-evolution with star formation and black hole activity.

Findings

Luminous LINERs have high star formation rates and stellar masses.

Most sources show AGN luminosity comparable to star formation luminosity.

Luminous LINERs are on the main sequence of star-forming galaxies.

Abstract

This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate LINERs at z = 0.04 - 0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and IRAS) for 13 of them. We measured emission line intensities, extinction, stellar populations, stellar masses, ages, AGN luminosities, and star-formation rates. We find considerable differences from other low-redshift LINERs, in terms of extinction, and general similarity to star forming (SF) galaxies. We confirm the existence of such luminous LINERs in the local universe, after being previously detected at z ~ 0.3 by Tommasin et al. (2012). The median stellar mass of these LINERs corresponds to 6 - 7 $\times$ 10$^{10}$M$_{\odot}$ which was found in previous work to correspond to the peak of relative growth rate of stellar populations and therefore for the highest SFRs. Other LINERs although showing similar AGN luminosities have lower SFR. We find that most of these sources have LAGN ~ LSF suggesting co-evolution of black hole and stellar mass. In general among local LINERs being on the main-sequence of SF galaxies is related to their AGN luminosity.