A high signal-to-noise HST spectrum towards J1009+0713: precise absorption measurements in the CGM of two galaxies

摘要: High signal-to-noise spectra toward background quasars are crucial for uncovering weak absorption in the circumgalactic medium (CGM) of intervening galaxies, such as diagnostic lines N V that provide insight to ionization process warm gas but typically have low equivalent widths. We present a new spectrum from Hubble Space Telescope with ratio $\sim20-35$ quasar SDSS J1009+0713 and analyze systems CGM two $L^\star$ galaxies close line sight. identify additional these was not reported by previous lower spectrum, well Milky Way absorbers outflows J1009+0713. measure $\log (N_\mathrm{NV}/N_\mathrm{OVI})\sim-1.1$ absorbers, inconsistent collisional equilibrium consistent radiatively cooling bulk flow $\sim50-150$ km s$^{-1}$, which could be produced galactic winds. These column density ratios also those found other some Way's halo. place upper limits (N_\mathrm{NV}/N_\mathrm{OVI})<-1.8$ $-1.2$ O VI same halos, suggests is different processes parts CGM, even within Together kinematically structure high- low-ionization lines, results indicate there many components single galaxy's gaseous find redshift number Ly-$\alpha$ forest broad expectations at this redshift.