The VIMOS Public Extragalactic Redshift Survey (VIPERS). AGN feedback in [NeV] emitters

TL;DR

This study uses a novel single-line diagnostic to identify AGNs in galaxies at 0.62<z<1.2 from VIPERS, revealing new insights into AGN activity's role in galaxy evolution, especially in the blue cloud and green valley.

Contribution

It introduces an unconventional [NeV]-based method for AGN identification and uncovers a new class of active galaxies with post-starburst features.

Findings

Younger stellar ages in active galaxies compared to controls.

Higher [OII] luminosities in active galaxies within the green valley and blue cloud.

Discovery of a class of active galaxies with post-starburst spectral signatures.

Abstract

Using an unconventional single line diagnostic that unambiguously identifies AGNs in composite galaxies we report statistical differences in the properties (stellar age, [OII] luminosity, colour) between active and inactive galaxies at 0.62<z<1.2 extracted from the VIMOS Public Extragalactic Redshift Survey (VIPERS). The nuclear activity is probed by the high-ionization [NeV] emission line and along with their parent samples, the galaxies are properly selected according to their stellar mass, redshift, and colour distributions. We report younger underlying stellar ages and higher [OII] luminosities of active galaxies in the green valley and in the blue cloud compared to control samples. We observe higher fractions of green galaxies hosting AGN activity at progressively bluer (r-K) colours. Depending on the location of the host galaxy in the NUVrK colour diagram we find higher AGN fractions in massive blue galaxies and in the least massive red galaxies, in agreement with the picture that black holes vary their properties when hosted in either star-forming or passive galaxies. Exactly where the fast quenching processes are expected to play a role, we identify a novel class of active galaxies in the blue cloud with signatures typical for a suddenly suppression of their star formation activity after a burst happening in the recent past. Their optical spectra resemble those of post-starburst galaxies, that would never be identified in a spectroscopic search using classical selection techniques. Broadly, these active galaxies selected on the [NeV] line are not commonly represented in shallow X-ray, mid-IR, or classical line diagnostics. If we consider that our results are limited by the shallow observational limits and rapid AGN variability, the impact of AGN feedback on galaxy formation and evolution may represent an important channel of fast-transiting galaxies moving to the red sequence.