CMB Instrumentation Talk: Probing the cosmic star formation history from the stratosphere: an overview of the Terahertz Intensity Mapper mission

Speaker: Frank Fu (University of Illinois Urbana-Champaign) In Person

Understanding how galaxies grew and evolved over cosmic time remains one of the most profound questions in modern astrophysics, with half of all star formation hidden behind dust and visible only at far-infrared wavelengths. However, these wavelengths are largely inaccessible from the ground due to atmospheric absorption, making comprehensive surveys extremely challenging. The Terahertz Intensity Mapper (TIM), a balloon-borne spectroscopic telescope operating in the stratosphere, is designed to overcome these limitations by mapping galaxies during the peak epoch of cosmic star formation. TIM will pioneer the technique of line intensity mapping at far-infrared wavelengths (240-420 µm). It employs two grating spectrometers coupled to over 7,000 superconducting kinetic inductance detectors, achieving unprecedented sensitivity to trace star formation through the [CII] 158µm emission line. Combined with data from existing and future spectroscopic surveys, TIM’s observations will enable further constraints on the star formation rate density through cross-correlation and stacking analyses. In this talk, I will present an overview of the TIM mission, focusing on its science goals, instrument design, and current status—including our recent test flight in Ft. Sumner, NM.