Title: The Terahertz Intensity Mapper (TIM)
Abstract: Understanding the formation and evolution of galaxies over cosmic time is one of the foremost goals of astrophysics and cosmology today. The cosmic star formation rate has undergone a dramatic evolution over the course of the last 14 billion years, and dust-obscuration hides a large portion of this evolution from view in the optical. A variety of important, bright, and unextincted diagnostic lines are present in the far-infrared (FIR) which can provide crucial insight into the physical conditions of galaxy evolution. FIR spectroscopy is technically difficult but scientifically crucial for understanding galaxy evolution. The FIR waveband is impossible to observe from the ground, and spans a crucial gap in the spectroscopic coverage between the Atacama Large Millimeter/submillimeter Array (ALMA) in the sub/mm, and the James Webb Space Telescope (JWST) in the mid-IR. Stratospheric balloons offer a platform which can outperform current instruments and are the only way to provide large-area, wide-bandwidth spatial/spectral mapping at FIR wavelengths.
I will describe a newly funded instrument, the Terahertz Intensity Mapper (TIM), a balloon-borne telescope with a long-slit spectrometer designed to produce maps of the 3-D structure of the Universe using redshift tomography (''intensity mapping'') primarily in the 158 micron line of ionized carbon [CII], a strong emission line in the interstellar medium of galaxies. TIM will provide new insight into the conditions of star formation when the cosmic star formation rate was at its peak, and lay important groundwork for extending the technique of intensity mapping to even higher redshifts and to extracting the maximal scientific information using cross-correlations with other emission lines in the TIM data cubes and in combination with other galaxy surveys.