Mapping large-scale-structure evolution over cosmic times

Abstract

This paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

Neutrino Properties with Ground-Based Millimeter-Wavelength Line Intensity Mapping

“…At such large numbers of spectrometer-hours, the constraints become primarily limited by cosmic variance, so that sites that can observe a larger sky fraction become highly desirable. A space-based mission would be capable of measuring the largest possible sky area, and our analysis suggests that constraints on neutrinos-along with other cosmological parameters-may be strong science motivators for potential futuristic space-based LIM surveys now being discussed (e.g., Delabrouille et al 2019;Silva et al 2021).…”

Snowmass2021 Cosmic Frontier: Cosmic Microwave Background Measurements White Paper

“…This "Voyage 2050" process defined the science themes for the next three large-class (L-class, ∼ 1 billion Euro) missions, but did not yet define the specific mission concepts. A coordinated series of whitepapers proposed science themes on spectral distortions [96], on using the CMB as a backlight for mapping structures and their baryon content [97], on cosmology via probing structure evolution across cosmic times with line-intensity mapping [98], and on an L-class mission to target them all, with compromises to be made between the different science cases [99]. The Final recommendations from the Voyage 2050 Senior Committee [100] selected "New Physical Probes of the Early Universe" as one of the science themes, and recommended "a Large mission deploying gravitational wave detectors or precision microwave spectrometers to explore the early Universe at large redshifts."…”

LIMpy: A Semianalytic Approach to Simulating Multiline Intensity Maps at Millimeter Wavelengths

“…Furthermore, mapping the Universe using various rotational transitions of CO (J-level transition) can probe the formation of structures at high redshifts, offering insights into the process of reionization and the SFH of the first-generation galaxies (Kovetz et al 2017;Breysse et al 2022). Employing a tomographic approach to exploring the Universe enables the measurement of key quantities, including the growth factor of structures, the Hubble constant, and the equation of the state of dark energy (Kovetz et al 2017;Karkare & Bird 2018;Bernal et al 2019b;Silva et al 2021). A joint analysis of all lines could prove valuable for constraining the inflationary paradigm by limiting f NL (Bernal et al 2019a;Moradinezhad Dizgah & Keating 2019;Chen & Pullen 2022).…”