Impact of Radio-mode Feedback on the Covering Fraction of the Circumgalactic Medium of Quasars

Abstract Utilizing data from the Low-Frequency Array Two-meter Sky Survey and the Sloan Digital Sky Survey, we assemble a sample of 1469 projected quasar pairs with detected radio emissions from foreground quasars, as well as a control sample of 5846 pairs without detected radio emission, with the aim being to assess the impact of radio-mode feedback from quasars on the characteristics of the circumgalactic medium (CGM). By analyzing transverse Mg ii absorption lines associated with foreground quasars in the spectra of background quasars, we observe that the Mg ii covering fraction ( f c ) for quasars with detected radio emissions is significantly higher (∼3 σ ) than those without radio detections at projected distances d p ≤ 100 kpc, while no significant differences are noted on larger scales. Furtherly, if we remove the radio-quiet quasars from our sample, we find that this discrepancy between radio-loud quasars and the control group becomes even more significant. However, at larger projected distances, all types of quasars tend to have similar covering fractions. These findings suggest that radio-mode feedback from quasars may substantially influence the properties of the CGM on specific scales, particularly as quasars with radio emissions possess more powerful jets, enabling them to expel gas more effectively across various scales. This study offers new insights into the role of radio-mode feedback in galaxy evolution and underscores the importance of jets in regulating the gas distribution within the CGM.