Characterizing the Interstellar Medium with Stacked Spectra of Ten Million Galaxies
| Program ID | 19082 |
|---|---|
| Science Category | Interstellar Medium |
| Program Type | Analysis |
| Category | Small |
| Principal Investigator | Nikko Cleri |
| PI Institution | Pennsylvania State University |
| Co-Investigators |
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| Abstract | Roman grism spectroscopy from the Wide Field Instrument (WFI) will unlock the gas physics of over ten million galaxies across cosmic time. We will maximize the wealth of spectroscopy from Roman by stacking 10^7 spectra of emission line galaxies in the High Latitude Wide Area Survey (HLWAS) Medium Tier by redshifts, magnitudes, rest-frame colors, star formation rates, and emission line equivalent widths to trace population-level chemical evolution, temperatures, densities, and ionization conditions at 0.5<z<3. Our stacked spectra will reveal the otherwise too-faint auroral emission lines, which are the best tracers of extragalactic gas-phase temperatures and metallicities. We will join these stacked spectra with photoionization models to fully characterize the gas physics using all available data. Our approach will flexibly model the contribution of each emission line in the spectrum from multiple unresolved physical regions on sub-galaxy scales. |