Investigation on young radio AGNs based on SDSS spectroscopy

Abstract

The Gigahertz Peaked Spectrum (GPS) sources, Compact Steep Spectrum (CSS) radio sources, and High Frequency Peakers (HFP) radio sources are thought to be young radio AGNs, at the early stage of AGN evolution. We investigated the optical properties of the largest sample of 126 young radio AGNs based on the spectra in SDSS DR12. We find the black hole masses M BH range from 10 7.32 to 10 9.84 M ⊙ , and the Eddington ratios R edd vary from 10 −4.93 to 10 0.37 , suggesting that young radio AGNs have various accretion activities and not all are accreting at high accretion rate. Our young radio sources generally follow the evolutionary trend towards large-scale radio galaxies with increasing linear size and decreasing accretion rate in the radio power -linear size diagram. The radio properties of low luminosity young radio AGNs with low R edd are discussed. The line width of [O III] λ 5007 core (σ [OIII] ) is found to be a good surrogate of stellar velocity dispersion σ * . The radio luminosity L 5GHz correlates strongly with [O III] core luminosity L [OIII] , suggesting that radio activity and accretion are closely related in young radio sources. We find one object that can be defined as narrow-line Seyfert 1 galaxies (NLS1s), representing a population of young AGNs both with young jet and early accretion activity. The optical variabilities of 15 quasars with multi-epoch spectroscopy were investigated. Our results show that the optical variability in young AGN quasars presents low variations ( 60%) similar to the normal radio-quiet quasars.

Caltech-NRAO Stripe 82 Survey (CNSS). IV. The Birth of Radio-loud Quasar 013815+00

“…The estimated values of the black hole mass and Eddington ratio of 013815+00 are in agreement with those calculated for other young AGNs, although the range of these values for AGNs considered young is very wide (Berton et al 2017;Liao & Gu 2020). The accretion power of 013815+00 is larger than its jet power, which implies low jet efficiency P j /L bol ∼ 0.02 and makes the source comparable to flat-spectrum radio quasars (FSRQ) and high-excitation FRII objects (Rusinek et al 2017;Fan & Wu 2019;Wójtowicz et al 2020).…”

Jet-Induced Feedback in the [O III] Lines of Early Evolution Stage Active Galactic Nuclei

“…In this work, instead, we make use of a more rigorous classification based directly on the observed radio properties and morphology of the sources. The relativistic jets of NLS1s are usually rather compact [73,[87][88][89], although some exceptions are known (e.g., [90][91][92][93][94][95]). This has led some authors to suggest that NLS1s may be connected with classes of young radio galaxies such as compact steep-spectrum (CSS) sources and gigahertz-peaked sources (GPS) [38,89,[96][97][98][99][100][101][102].…”

“…The relativistic jets of NLS1s are usually rather compact [73,[87][88][89], although some exceptions are known (e.g., [90][91][92][93][94][95]). This has led some authors to suggest that NLS1s may be connected with classes of young radio galaxies such as compact steep-spectrum (CSS) sources and gigahertz-peaked sources (GPS) [38,89,[96][97][98][99][100][101][102]. Indeed, several radio galaxies show signs of line shifts and broadening induced by the presence of jets [40,86,103,104], and this seems particularly common in young radio galaxies, where the jet is directly interacting with the ISM [105,106].…”

Relativistic Jets in Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies

“…For these reasons some of the sources included in that catalog can be considered just as candidate NLSy1 and not bona-fide NLSy1, including the three FSRQ tentatively re-classified by [59] and the γ-ray sources NVSS J093241+530633 and NVSS J095820+322401 reported in [59] 4 . In order to investigate the properties of the γ-ray-emitting NLSy1, it is important to start considering only bona-fide NLSy1, not mixing these 4 In the same way, 3C 286 is classified as a Compact Steep Spectrum source in the 4FGL, while it is tentatively re-classified as a NLSy1 in [73,74]. The FWHM(Hβ) value reported in [74] exceeds the historical threshold of 2000 km s −1 , therefore 3C 286 could be considered as a candidate NLSy1.…”

“…In order to investigate the properties of the γ-ray-emitting NLSy1, it is important to start considering only bona-fide NLSy1, not mixing these 4 In the same way, 3C 286 is classified as a Compact Steep Spectrum source in the 4FGL, while it is tentatively re-classified as a NLSy1 in [73,74]. The FWHM(Hβ) value reported in [74] exceeds the historical threshold of 2000 km s −1 , therefore 3C 286 could be considered as a candidate NLSy1. It is worth nothing also that the inclination angle between the jet and our line of sight is 48 degrees [75], significantly different from the relatively small angles estimated for the γ-ray-emitting NLSy1.…”