Speaker
Description
Galaxies do not form in isolation, but rather evolve symbiotically with the wider cosmic web. At the interface between a galaxy's Interstellar Medium (ISM) and the Inter-Galactic Medium (IGM) is the Circum-Galactic Medium (CGM) in which all matter flowing in from the IGM or out of the galaxy must travel. This halo of gas is therefore sensitive to both the evolutionary processes occurring within the central galaxy, and its environment. Conversely, the physical properties of the CGM impact the transport and timescales of gas flows, thus regulating the growth and evolution of the galaxy. At high redshift, where feedback and fuelling are expected to be most extreme due to rapid galaxy evolution, the CGM is of particular interest; however, detecting the faint signatures of gas in this extended and diffuse reservoir is extremely difficult. Particular observational success has been made targeting molecular absorption lines ($\rm OH^+$, $\rm CH^+$, $\rm H_2O^+$, ect.) towards dusty high-z galaxies in combination with strong gravitational lensing. Current samples reach almost 100% detection rates in such galaxies, with high rates of inflowing and outflowing gas (red and blue-shifted absorption. With such success, higher spatial resolution observations have been taken to explore in greater detail the properties of the neutral CGM and gas flows in high-z dusty galaxies. In this talk, I will present OH+ absorption observations in a sample of high-z dusty star-forming galaxies that allow comparison with the underlying kinematic structure of the galaxy. Our results build on existing evidence that OH+ absorption traces diffuse neutral gas in the CGM; however, we also find new evidence that some fraction likely originates from the ISM. We additionally find that current in/outflow detection rates estimated from low S/N or unresolved observations, particularly in gravitationally lensed galaxies, are likely overestimated due to blended spectral features and differential lensing effects.