Colloquium Abstract - Pingel - 2024Feb09

February 9, 2024

11:00am Mountain

Nick Pingel (U Wisc)

 

Revealing the Hidden Cold Neutral Medium: LGLBS Insights Beyond the Milky Way

 

Abstract

Star formation originates from gravitational instabilities that induce the collapse of cold and dense molecular hydrogen gas. Thus, the physical state and spatial distribution of the cold gas content of galaxies is crucial for testing models explaining the process of star formation. The cold neutral medium (CNM) phase of atomic neutral hydrogen (HI), a precursor to the molecular gas phase, is an unambiguous tracer of the cold gas content but, due to its inherently low spin temperature, is only reliably detected in absorption against serendipitous strong background sources. However, sensitivity constraints have limited our systematic measurement of the physical state of the CNM to HI absorption in our own Milky Way and nearby Magellanic System. With improved sensitivities and wide-field surveys like the Local Group L-Band Survey (LGLBS) conducted with the Karl G. Jansky Very Large Array, we can now measure localized HI absorption in other members of the Local Group, enabling the study of the spatial distribution of the CNM properties in these external galaxies. In addition to highlighting the spectacular quality of these data, I will present the first detections of HI absorption from these nearby dwarf galaxies that span a wide range of metallicities, comparisons of the derived spin temperature and cold HI fraction with what has been measured for the Milky Way and nearby Magellanic System, and share progress from various early science projects from LGLBS that will be published this year.


Local Host: Preshanth Jagannathan

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