11/18: 2nd Year Project: Jed McKinney

LGRT 1033, 4:00pm

Title: Measuring the Heating and Cooling of the Interstellar Medium at High Redshift : PAH and [C II] Observations of the Same Star Forming Galaxies at z ~ 2

Abstract: Star formation depends critically on cooling mechanisms in the interstellar medium (ISM); however, thermal properties of gas in galaxies at the peak epoch of star formation (z ∼ 2) remain poorly understood. In this talk, I will compare low- and  high-redshift observations of [C II] emission, a principal cooling channel, with observations of Polycyclic Aromatic Hydrocarbons (PAHs), a measure of photoelectric heating in photodissociation regions (PDRs). I will discuss the diagnostic power of combining these tracers in the same dusty, star forming galaxies at z ~ 2, and how they may be used to study cosmological trends in galaxy evolution. In particular, changes in the [C II]/PAH ratio with redshift can trace evolution in the physical PDR conditions with implications for the star-formation efficiency. Finally, I will summarize ongoing and future projects that aim to characterize PDRs in nearby and z ~ 2 galaxies.