Carbon monoxide and ionized carbon line emission global signals: foregrounds and targets for absolute microwave spectrometry

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Hauptverfasser: Chung, Dongwoo T, Chluba, Jens, Breysse, Patrick C
Format: Preprint
Veröffentlicht: 2023
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author Chung, Dongwoo T
Chluba, Jens
Breysse, Patrick C
author_facet Chung, Dongwoo T
Chluba, Jens
Breysse, Patrick C
contents (abr.) We consider the potential of future microwave spectrometers akin to PIXIE in light of the sky-averaged global signal expected from the total intensity of extragalactic carbon monoxide (CO) and ionized carbon ([CII]) line emission. We start from models originally developed for forecasts of line-intensity mapping (LIM) observations targeting the same line emission at specific redshifts, extrapolating them across all of cosmic time. We then calculate Fisher forecasts for uncertainties on parameters describing relic spectral deviations, the CO/[CII] global signal, and a range of other Galactic and extragalactic foregrounds considered in previous work. We find that the measurement of the CO/[CII] global signal with a future CMB spectrometer presents an exciting opportunity to constrain the evolution of metallicity and molecular gas in galaxies across cosmic time. From PIXIE to its enhanced version, SuperPIXIE, microwave spectrometers would have the fundamental sensitivity to constrain the redshift evolution of average kinetic temperature and cosmic molecular gas density at a level of 10% to 1%, respectively. Taking a spectral distortion-centric perspective, when combined with other foregrounds, sky-averaged CO/[CII] emission can mimic $μ$- and to a lesser extent $y$-type distortions. Under fiducial parameters, marginalising over the CO/[CII] model parameters increases the error on $μ$ by $\simeq86$%, and the error on $y$ by $\simeq10$%. Incorporating information from planned CO LIM surveys can recover some of this loss in precision. Future work should deploy a more general treatment of the microwave sky to quantify in more detail the potential synergies between PIXIE-like and CO LIM experiments, which complement each other strongly in breadth versus depth, and ways to optimise both spectrometer and LIM surveys to improve foreground cleaning and maximise the science return for each.
format Preprint
id arxiv_https___arxiv_org_abs_2311_03297
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Carbon monoxide and ionized carbon line emission global signals: foregrounds and targets for absolute microwave spectrometry
Chung, Dongwoo T
Chluba, Jens
Breysse, Patrick C
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
(abr.) We consider the potential of future microwave spectrometers akin to PIXIE in light of the sky-averaged global signal expected from the total intensity of extragalactic carbon monoxide (CO) and ionized carbon ([CII]) line emission. We start from models originally developed for forecasts of line-intensity mapping (LIM) observations targeting the same line emission at specific redshifts, extrapolating them across all of cosmic time. We then calculate Fisher forecasts for uncertainties on parameters describing relic spectral deviations, the CO/[CII] global signal, and a range of other Galactic and extragalactic foregrounds considered in previous work. We find that the measurement of the CO/[CII] global signal with a future CMB spectrometer presents an exciting opportunity to constrain the evolution of metallicity and molecular gas in galaxies across cosmic time. From PIXIE to its enhanced version, SuperPIXIE, microwave spectrometers would have the fundamental sensitivity to constrain the redshift evolution of average kinetic temperature and cosmic molecular gas density at a level of 10% to 1%, respectively. Taking a spectral distortion-centric perspective, when combined with other foregrounds, sky-averaged CO/[CII] emission can mimic $μ$- and to a lesser extent $y$-type distortions. Under fiducial parameters, marginalising over the CO/[CII] model parameters increases the error on $μ$ by $\simeq86$%, and the error on $y$ by $\simeq10$%. Incorporating information from planned CO LIM surveys can recover some of this loss in precision. Future work should deploy a more general treatment of the microwave sky to quantify in more detail the potential synergies between PIXIE-like and CO LIM experiments, which complement each other strongly in breadth versus depth, and ways to optimise both spectrometer and LIM surveys to improve foreground cleaning and maximise the science return for each.
title Carbon monoxide and ionized carbon line emission global signals: foregrounds and targets for absolute microwave spectrometry
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2311.03297