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ABSTRACT Line intensity mapping (LIM) is rapidly emerging as a powerful technique to study galaxy formation and cosmology in the high-redshift Universe. We present LIM estimates of select spectral lines originating from the interstellar medium (ISM) of galaxies and 21 cm emission from neutral hydrogen gas in the Universe using the large volume, high resolution thesan reionization simulations. A combination of subresolution photoionization modelling for H ii regions and Monte Carlo radiative transfer calculations is employed to estimate the dust-attenuated spectral energy distributions (SEDs) of high-redshift galaxies (z ≳ 5.5). We show that the derived photometric properties such as the ultraviolet (UV) luminosity function and the UV continuum slopes match observationally inferred values, demonstrating the accuracy of the SED modelling. We provide fits to the luminosity–star formation rate relation (L–SFR) for the brightest emission lines and find that important differences exist between the derived scaling relations and the widely used low-z ones because the ISM of reionization era galaxies is generally less metal enriched than in their low-redshift counterparts. We use these relations to construct line intensity maps of nebular emission lines and cross-correlate with the 21 cm emission. Interestingly, the wavenumber at which the correlation switches sign (ktransition) depends heavily on the reionization model and to a lesser extent on the targeted emission line, which is consistent with the picture that ktransition probes the typical sizes of ionized regions. The derived scaling relations and intensity maps represent a timely state-of-the-art framework for forecasting and interpreting results from current and upcoming LIM experiments.
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Constraining the star formation rate using joint CIB continuum and C ii intensity mapping
ABSTRACT Line intensity mapping (LIM) experiments probing the nearby Universe can expect a considerable amount of cosmic infrared background (CIB) continuum emission from near and far-infrared galaxies. For the purpose of using LIM to constrain the star formation rate (SFR), we argue that the CIB continuum – traditionally treated as contamination – can be combined with the LIM signal to enhance the SFR constraints achievable. We first present a power spectrum model that combines continuum and line emissions assuming a common SFR model. We subsequently analyse the effectiveness of the joint model in the context of the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM), which utilizes the $$[{\rm C\, \small {II}}]$$ molecular line to study the SFR. We numerically compute the theoretical power spectra according to our model and the EXCLAIM survey specifics, and perform Fisher analysis to forecast the SFR constraints. We find that although the joint model has no considerable advantage over LIM alone assuming the current survey level of EXCLAIM, its effects become significant when we consider more optimistic values of survey resolution and angular span that are expected of future LIM experiments. We show that the CIB is not only an additional SFR sensitive signal, but also serves to break the SFR parameter degeneracy that naturally emerges from the $$[{\rm C\, \small {II}}]$$ Fisher matrix. For this reason, addition of the CIB will allow improvements in the survey parameters to be better reflected in the SFR constraints, and can be effectively utilized by future LIM experiments.
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- Award ID(s):
- 2108411
- PAR ID:
- 10437554
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 524
- Issue:
- 4
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 5254-5265
- Size(s):
- p. 5254-5265
- Sponsoring Org:
- National Science Foundation
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