2024ApJ...970..115G

We present an analysis of Hubble Space Telescope COS/G160M observations of C IV in the inner circumgalactic medium (CGM) of a novel sample of eight z ∼ 0, L ≈ L^⋆ galaxies, paired with UV-bright QSOs at impact parameters (R_proj) between 25 and 130 kpc. The galaxies in this stellar-mass-controlled sample (log₁₀M_⋆/M_⊙ ∼ 10.2-10.9 M_⊙) host supermassive black holes (SMBHs) with dynamically measured masses spanning log₁₀M_BH/M_⊙ ∼ 6.8-8.4; this allows us to compare our results with models of galaxy formation where the integrated feedback history from the SMBH alters the CGM over long timescales. We find that the C IV column density measurements (N_C IV_; average log₁₀N_C IV,CH_ = 13.94 ± 0.09 cm^–2) are largely consistent with existing measurements from other surveys of N_C IV_ in the CGM (average log₁₀N_C IV,Lit_ = 13.90 ± 0.08 cm^–2), but do not show obvious variation as a function of the SMBH mass. By contrast, specific star formation rate (sSFR) is highly correlated with the ionized content of the CGM. We find a large spread in sSFR for galaxies with log₁₀M_BH/M_⊙ > 7.0, where the CGM C IV content shows a clear dependence on galaxy sSFR but not M_BH. Our results do not indicate an obvious causal link between CGM C IV and the mass of the galaxy's SMBH; however, through comparisons to the EAGLE, Romulus25, and IllustrisTNG simulations, we find that our sample is likely too small to constrain such causality.