High signal-to-noise spectra toward background quasars are crucial for uncovering weak absorption in the circumgalactic medium ( CGM ) of intervening galaxies , such as the diagnostic lines of N v that provide insight to the ionization process of warm gas but typically have low equivalent widths .
We present a new spectrum from the Hubble Space Telescope with a signal-to-noise ratio of \sim 20 - 35 toward the quasar SDSS J1009+0713 and analyze absorption systems in the CGM of two L ^ { \star } galaxies close to the line of sight .
We identify additional absorption in the CGM of these galaxies that was not reported by the previous lower signal-to-noise spectrum , as well as Milky Way absorbers and quasar outflows from J1009+0713 .
We measure \log ( N _ { \mathrm { NV } } / N _ { \mathrm { OVI } } ) \sim - 1.1 for two CGM absorbers , inconsistent with gas in collisional ionization equilibrium and consistent with a radiatively cooling bulk flow of \sim 50 - 150 km s ^ { -1 } , which could be produced by galactic winds .
These column density ratios are also consistent with those found for other L ^ { \star } galaxies and for some gas in the Milky Way ’ s halo .
We place upper limits of \log ( N _ { \mathrm { NV } } / N _ { \mathrm { OVI } } ) < -1.8 to -1.2 for other O vi absorbers in the same halos , which suggests that O vi is produced by different processes in different parts of the CGM , even within the same galactic halo .
Together with the kinematically different structure of high- and low-ionization lines , these results indicate there are many components to a single galaxy ’ s gaseous halo .
We find the redshift number density of Ly- \alpha forest absorbers and broad Ly- \alpha absorbers are consistent with expectations at this redshift .