Properties of radio-loud quasars in the Sloan Digital Sky Survey

Abstract

We present a study of a sample of 223 radio loud quasars (up to redshift <0.3) in order to investigate their spectral properties. Twentysix of these radio loud quasars are identified as Flat Spectrum Radio Quasars (FSRQs) and fifty-four are identified as Steep Spectrum Radio Quasars (SSRQs) based on their radio spectral index. We study the [O III] line properties of these quasars to investigate the origin and properties of blue wings (shift of the profile towards lower wavelengths) and blue outliers (shift of the whole spectroscopic feature). Most of the quasars show blue wings with velocities up to 420 km s −1 . We find that around 17% of the quasars show outliers with velocities spanning 419 to -315 km s −1 . Finally, we revisit the M BH − σ relation of our sample using [S II]λ6716, 6731 and [O III] linewidths as surrogates for stellar velocity dispersions, σ, to investigate their location on the M BH − σ relation for quiescent galaxies. Due to strong blending of [S II] with H α , we could estimate σ [SII] of only 123 quasars. We find that the radio-loud quasars do not show a relationship between M BH and σ [SII]/ [OIII] up to a redshift of 0.3, although they cluster around the local relation. We find an overall offset of 0.12±0.05 dex of our sample of radio loud quasars from the M BH − σ relation of quiescent galaxies. Quasars in our highest redshift bin (z=0.25-0.3) show a deviation of ∼0.33 ± 0.06 dex with respect to the local relation.

Selection of highly-accreting quasars

“…The highest amplitude blueshift at 0.9 peak intensity is ≈−150 km s −1 . The distribution of c( 1 4 ) values is skewed toward blueshifts, as observed in most samples (e.g., Gaur et al 2019;Berton et al 2016;Zhang et al 2011), in both Pop. A and Pop.…”

Properties of Broad and Narrow Line Seyfert galaxies selected from SDSS

“…PyQSOFIT 2 , a publicly available code to fit the quasar spectra has been used to analyse the individual spectra. It is written in Python language, and has been used for fitting the SDSS quasar spectra recently (see Gaur et al, 2019, Rakshit et al, 2020. Initially, the continuum model is prepared using the host galaxy components, contribution from the iron line and the accretion disk emission which reflects itself as a power law component (see Figure 2).…”