Kavli Affiliate: Robert Simcoe
| Summary:
We present the GOLIATH survey (Galaxies, Outflows, and the Lifecycle of Immense, Active, Transforming Halos), a study of the multiphase circumgalactic medium (CGM) of massive ($langlelog M_star/M_odotrangle approx 11$), blue ($u-r < 1.65$) starburst and post-starburst galaxies at $langle zrangle approx$ 0.43. This work characterizes the warm-hot CGM through OVI absorption in the inner halo ($R/R_rm vir leq 0.6$) of these rare systems. Across the star-forming population, OVI column density rises by nearly 1~dex from $log M_star/M_odot sim 8$ to $sim 11.5$ and increases with specific star-formation rate (sSFR). Two GOLIATH galaxies with the highest sSFR show the strongest CGM OVI absorption ($log N_rm O,VI[rm cm^-2] gtrsim 15$). In the $log M_star/M_odot = [11,12)$ inner-CGM region, massive star-forming galaxies exceed quiescent galaxies on average by a factor of $sim 3$ in OVI column density and $sim 1.5$~dex in CGM OVI mass ($log(M_rm O, VI/M_odot) approx 7.3$ versus $approx 5.8$), with covering fractions roughly three times higher (62.5% versus 24% at $log N_rm O,VI[rm cm^-2] geq 14$). The OVI line widths and column densities are consistent with feedback-driven radiative cooling, in which outflow shocks heat the CGM and the gas cools back through the OVI window; the short cooling time, $t_rm cool sim 10$-$100$~Myr, requires continuous replenishment by active feedback to sustain this reservoir. The residual OVI in quiescent systems may arise from ambient gas at the high-temperature end of the cooling curve. OVI thus traces feedback on short timescales and probes the star-forming–quiescent transition at $log M_star/M_odot gtrsim 11$.
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