The radio spectra of reddened 2MASS QSOs: evidence for young radio jets

TL;DR

This study presents multifrequency radio observations of reddened QSOs, revealing young radio jets and spectral features similar to CSS and GPS sources, supporting the idea that these QSOs are in early evolutionary stages of black hole growth.

Contribution

It provides evidence that reddened QSOs host young radio jets, with spectral properties indicating early AGN evolution, based on multifrequency radio data analysis.

Findings

High incidence of spectral features similar to CSS and GPS sources.

Radio jet ages estimated to be less than 10 million years.

One source shows an extremely young radio age of less than 2,000 years.

Abstract

Multifrequency radio continuum observations (1.4-22 GHz) of a sample of reddened QSOs are presented. We find a high incidence (13/16) of radio spectral properties, such as low frequency turnovers, high frequency spectral breaks or steep power-law slopes, similar to those observed in powerful compact steep spectrum (CSS) and gigahertz-peaked spectrum (GPS) sources. The radio data are consistent with relatively young radio jets with synchotron ages <1e6-1e7yr. This calculation is limited by the lack of high resolution (milli-arcsec) radio observations. For the one source in the sample that such data are available a much younger radio age is determined, <2e3yr, similar to those of GPS/CSS sources. These findings are consistent with claims that reddened QSOs are young systems captured at the first stages of the growth of their supermassive black holes. It also suggests that expanding radio lobes may be an important feedback mode at the early stages of the evolution of AGN.