Abstract

Contributed Talk - Splinter LIM

Friday, 11 September 2026, 14:00   (MW-2050)

The FYST Line Intensity Mapping Survey : Interloper Mitigation with Enhanced Spectral Line Deconfusion

Tejas Oak
Argelander Institute for Astronomy, University of Bonn

Probing the star formation activity of the galaxies during the epoch of reionization (EoR) is essential to understand how exactly the stellar populations drove and sustained reionization. However, this problem is challenging, as these sources are extremely distant and faint to detect individually with current telescopes. Line Intensity Mapping (LIM), overcomes this limitation by measuring the aggregate line emission from galaxies across large cosmic volumes with a broad beam. The Epoch of Reionization Spectrometer (EoR-Spec) onboard the Fred Young Submillimeter Telescope (FYST) will conduct LIM experiment targeting the [CII] (158 μm) fine-structure line, which is a direct tracer of star formation and observable from the ground in the submillimeter transmission window 1. A major challenge in [CII] LIM is mitigating the contaminating CO emission from the galaxies at intermediate redshifts that spectrally overlap with the target signal. At EoR redshifts, the mean intensity of the CO emission is expected to be 1-2 orders of magnitude brighter than the signal 2. Additionally, similar fluctuation scales and frequency evolution of both the components makes their separation particularly difficult. To address this, we aim to develop an enhanced interloper mitigation strategy based on the spectral line deconfusion method 3. We apply our method to the mock tomographic data derived from post-processed IllustrisTNG simulations and evaluate its performance in recovering the [CII] power spectrum by fitting and subtracting the CO emission. We further examine the effect of injecting priors (position and star formation rates) from an ancillary galaxy survey to assist the signal recovery with an enhanced variation of this technique. As the instrumental white noise tends to destroy the multi-line correlations that this technique leverages, we also make sensitivity predictions for the EoR-Spec deep sky survey to conclusively detect [CII] clustering from relatively higher redshifts of ∼ 5.7. Our results show that the enhanced spectral line deconfusion technique is effective for interloper mitigation at low frequencies, where other techniques are expected to work with diminishing efficiency. This dedicated effort with FYST will assist in constraining the luminosity functions of EoR galaxies to address the long standing questions in understanding the evolution of our universe.