SIMBAD references

The incidence rate of Mg II absorbers per unit redshift path ($\mathrm{ d}N/\mathrm{ d}z$) towards quasars' sightline has been used to probe the interaction between quasar jets and surrounding gas clouds. Studies using core- and lobe-dominated samples found a higher $\mathrm{ d}N/\mathrm{ d}z$ for strong Mg II absorbers (rest equivalent width, $W_{r}(2796)\ge ~1.0~\rm{\mathring{\rm A}}$) in velocity offsets in the range 5000 $\text{km}\, \text{s}^{-1}$$<\beta c <~$60 000 $\text{km}\, \text{s}^{-1}$ (with $\beta \equiv v/c$), towards core-dominated sources. In this study, we applied a stringent spectral index criterion: $\alpha _{\text{radio}}~< -0.7$ for steep-spectrum radio quasars (SSRQs) and $\alpha _{\text{radio}} >-0.3~$ for flat-spectrum radio quasars (FSRQs). Using this, we assembled the largest sample till date - 441 FSRQs and 464 SSRQs with suitable optical spectra - to study both strong absorbers and weak ($0.3~\rm{\mathring{\rm A}}< W_r (2796)< 1.0$ Å) Mg II absorbers. We conducted a detailed comparison of absorbers' incidence rate and offset velocity distributions. Our main findings are as follows: (i) For both weak and strong absorbers, we found no significant excess in $\mathrm{ d}N/\mathrm{ d}z$ towards FSRQ compared to SSRQ sightlines. (ii) The $\mathrm{ d}N/\mathrm{ d}\beta$ distribution of Mg II absorbers along FSRQs and SSRQs is statistically similar. (iii) The cumulative distribution of weak Mg II absorbers is slightly lower for $\beta < 0.3$, but shows an excess at higher $\beta$. This suggests that, while intrinsic Mg II absorber abundance is comparable along both sightlines, FSRQs' more aligned relativistic jets cluster weak absorbers at high $\beta$, consistent with the scenario of jet-driven acceleration of smaller gas clumps.