2025ApJ...978L..12G

This paper investigates C IV absorption in the circumgalactic medium (CGM) of L^⋆ galaxies and its relationship with galaxy star formation rates. We present new observations from the C IV in L^⋆ galaxies survey (PID#17076) using the Hubble Space Telescope/Cosmic Origins Spectrograph. By combining these measurements with archival C IV data (46 observations total), we estimate detection fractions for star-forming (sSFR > 10^–11 yr^–1) and passive galaxies (sSFR ≤ 10^–11 yr^–1 ) to be 72${}_{-18}^{+14}$% [21/29] and 23${}_{-15}^{+27}$% [3/13], respectively. This indicates a significant dichotomy in C IV presence between L^⋆ star-forming and passive galaxies, with over 99% confidence. This finding aligns with J. Tumlinson et al., which noted a similar dichotomy in O VI absorption. Our results imply a substantial carbon reservoir in the CGM of L⋆ galaxies, suggesting a minimum carbon mass of ≳3.03 × 10⁶M_⊙ out to 120 kpc. Together, these findings highlight a strong connection between star formation in galaxies and the state of their CGM, providing insight into the mechanisms governing galaxy evolution.