Revisiting the [C ii] 158 μm line-intensity mapping power spectrum from the EoR using non-uniform line-luminosity scatter

Abstract

Detecting the line-intensity mapping (LIM) signal from the galaxies of the Epoch of Reionization is an emerging tool to constrain their role in reionization. Ongoing and upcoming experiments target the signal fluctuations across the sky to reveal statistical and astrophysical properties of these galaxies via signal statistics, e.g., the power spectrum. Here, we revisit the [C ii]$_{158 \mu \text{m}}$ LIM power spectrum under non-uniform line-luminosity scatter, which has a halo-mass variation of statistical properties. Line-luminosity scatter from a cosmological hydrodynamic and radiative transfer simulation of galaxies at z = 6 is considered in this study. We test the robustness of different model frameworks that interpret the impact of the line-luminosity scatter on the signal statistics. We use a simple power-law model to fit the scatter and demonstrate that the mean luminosity-halo mass correlation fit cannot preserve the mean intensity of the LIM signal (hence the clustering power spectrum) under non-uniform scatter. In our case, the mean intensity changes by ∼48 per cent compared to the mean correlation fit in contrast to the general case with semi-analytic scatter. However, we find that the prediction for the mean intensity from the most-probable fit can be modelled robustly, considering the generalized and more realistic non-uniform scatter. We also explore the possibility of diminishing luminosity bias under non-uniform scatter, affecting the clustering power spectrum, although this phenomenon might not be statistically significant. Therefore, we should adopt appropriate approaches that can consistently interpret the LIM power spectrum from observations.

Precision tests of CO and [CII] power spectra models against simulated intensity maps

“…Therefore, the generated Mithra LIMSims mocks allow very precise measurements of the cosmological observables, required for both forecasting and analysis of data from the next generation of LIM instruments. The presented mocks are complementary to the existing detailed, smaller volume LIM simulations, based on hydrodynamical cosmological simulations and semi-analytic models of galaxy formation (e.g., [44][45][46]).…”

“…Worthy to note that the recent results of ref. [45], in which the scatter inferred from the hydrodynamic and radiative transfer simulation of early galaxies [44] was applied to the halo distribution of a large-volume Nbody simulations, found an enhancement of the [CII] power spectrum by factor of ∼ 3 for [CII] power spectrum at z = 6.…”

LIMFAST. I. A Seminumerical Tool for Line Intensity Mapping

“…The density-field-based method allows for fast realizations (in a matter of hours) of multiple line intensity fields on a personal computer. While certain (potentially important) aspects of simulating the intensity fields and their synergies with other LSS tracers that are characteristic of "paint-on" simulations have not been implemented in LIMFAST yet, such as the inclusion of scatter in various relations (Reis et al 2022;Murmu et al 2023) and point sources like Lyα emitters, they can be included through relatively simple extensions of the current formalism using halo finders or subgrid sampling.…”

Cross-correlation Techniques to Mitigate the Interloper Contamination for Line Intensity Mapping Experiments

“…Zhou et al 2023b). The exploration of several lines, including fine-structure emissions like [C II] (157.7 μm) and [O III] (52 and 88.4 μm), along with rotational emission lines from CO, garners substantial interest in upcoming LIM experiments conducted at millimeter and submillimeter wavelengths (Suginohara et al 1998;Righi et al 2008;Carilli 2011;Lidz et al 2011;Fonseca et al 2017;Gong et al 2017;Kovetz et al 2017;Padmanabhan 2018Padmanabhan , 2019Chung et al 2019Chung et al , 2020Dumitru et al 2019;Kannan et al 2022;Karoumpis et al 2022;Murmu et al 2022;Garcia et al 2023;Sun et al 2023). These lines are of particular interest owing to their inherent brightness properties and frequency overlap with the current millimeter-and submillimeter-wavelength LIM experiments.…”