ABSTRACT
The wavelet scattering transform (WST) has recently gained attention in the context of large-scale structure studies, being a possible generator of summary statistics encapsulating ...non-Gaussianities beyond the reach of the conventional power spectrum. This work examines the three-dimensional solid harmonic WST in the context of a three-dimensional line-intensity mapping measurement to be undertaken by current and proposed phases of the CO Mapping Array Project (COMAP). The WST coefficients demonstrate interpretable behaviour in the context of noiseless CO line-intensity simulations. The contribution of the cosmological z ∼ 3 signal to these coefficients is also detectable in principle even in the Pathfinder phase of COMAP. Using the peak-patch method to generate large numbers of simulations and incorporating observational noise, we numerically estimate covariance matrices and show that careful choices of WST hyperparameters and rescaled or reduced coefficient sets are both necessary to keep covariances well-conditioned. Fisher forecasts show that even a reduced ‘shapeless’ set of ℓ-averaged WST coefficients show constraining power that can exceed that of the power spectrum alone even with similar detection significance. The full WST could improve parameter constraints even over the combination of the power spectrum and the voxel intensity distribution, showing that it uniquely encapsulates shape information about the line-intensity field. However, practical applications urgently require further understanding of the WST in key contexts like covariances and cross-correlations.
Line-intensity mapping, being an imperfect observation of the line-intensity field in a cosmological volume, will be subject to various anisotropies introduced in observation. Existing literature in ...the context of CO and C ii line-intensity mapping often predicts only the real-space, spherically averaged line-intensity power spectrum, with some works considering anisotropies while examining projection of interloper emission. We explicitly consider a simplified picture of redshift-space distortions and instrumental effects due to limited resolution, and how these distort an isotropic line-intensity signal in real space and introduce strong apparent anisotropies. The results suggest that while signal loss due to limited instrumental resolution is unavoidable, measuring the quadrupole power spectrum in addition to the monopole would still break parameter degeneracies present in monopole-only constraints, even without a measurement of the full anisotropic power spectrum.
ABSTRACT
The field of millimetre-wave line-intensity mapping (LIM) is seeing increased experimental activity with pathfinder surveys already deployed or deploying in the next few years, making ...spectroscopic measurements of unresolved atomic and molecular line emission tracing the large-scale structure of the Universe. The next decade will also see the Rubin Observatory Legacy Survey of Space and Time (LSST) undertake a photometric galaxy survey programme of unprecedented scope, including measurements of cosmic shear exploiting weak gravitational lensing (WL) of background galaxies to map projected large-scale structure. We consider prospects for detecting angular cross-power spectra between non-tomographic cosmic shear and mm-wave LIM surveys that measure emission from CO lines at z = 0.5–1. We forecast that once the LSST Year 10 WL data set is available, a future LIM experiment, conceivably deployed in the next 10–15 yr, would enable such a cross-correlation detection with an overall signal-to-noise ratio of 50, although the current pathfinder generation of CO/C ii surveys are more likely to achieve a marginal 2σ detection against an earlier-stage LSST WL data set. The signal has modest astrophysical constraining power yielding competitive constraints on cosmic molecular gas density at z ≲ 1, and degeneracies between astrophysical parameters and the intrinsic alignment amplitude mean that external information on either one could allow the cross-correlation analysis to significantly improve its constraints on the other.
ABSTRACT Line-intensity mapping (LIM) experiments coming online now will survey fluctuations in aggregate emission in the C ii ionized carbon line from galaxies at the end of reionization. ...Experimental progress must be matched by theoretical reassessments of approaches to modelling and the information content of the signal. We present a new model for the halo–C ii connection, building upon results from the Feedback In Realistic Environments simulations suggesting that gas mass and metallicity most directly determine C ii luminosity. Applying our new model to an ensemble of peak-patch halo light-cones, we generate new predictions for the C ii LIM signal at z ≳ 6. We expect a baseline 4000-h LIM survey from the Cerro Chajnantor Atacama Telescope facility to have the fundamental sensitivity to detect the C ii power spectrum at a significance of 5σ at z ∼ 6, with an extended or successor Stage 2 experiment improving significance to 48σ at z ∼ 6 and achieving 11σ at z ∼ 7.5. Cross-correlation through stacking, simulated against a mock narrow-band Lyman-break galaxy survey, would yield a strong detection of the radial profile of cosmological C ii emission surrounding star-forming galaxies. We also analyse the role of a few of our model’s parameters through the pointwise relative entropy (PRE) of the distribution of C ii intensities. While the PRE signature of different model parameters can become degenerate or diminished after factoring in observational distortions, various parameters do imprint themselves differently on the one-point statistics of the intrinsic signal. Further work can pave the way to access this information and distinguish different sources of non-Gaussianity in the C ii LIM observation.
The early Universe was dust-rich and extremely hot Viero, Marco P; Sun, Guochao; Chung, Dongwoo T ...
Monthly Notices of the Royal Astronomical Society Letters,
10/2022, Letnik:
516, Številka:
1
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We investigate the dust properties and star-formation signature of galaxies in the early Universe by stacking 111 227 objects in the recently released COSMOS catalogue on maps at wavelengths ...bracketing the peak of warmed dust emission. We find an elevated far-infrared luminosity density to redshift 8, indicating abundant dust in the early Universe. We further find an increase of dust temperature with redshift, reaching $100\pm 12\,\mathrm{ K}$ at $\mathit{z}$ ∼ 7, suggesting either the presence of silicate rich dust originating from Population ii stars, or sources of heating beyond simply young hot stars. Lastly, we try to understand how these objects have been missed in previous surveys, and how to design observations to target them. All code, links to the data, and instructions to reproduce this research in full are located at https://github.com/marcoviero/simstack3/.
ABSTRACT
We introduce a novel unbiased, cross-correlation estimator for the one-point statistics of cosmological random fields. One-point statistics are a useful tool for analysis of highly ...non-Gaussian density fields, while cross-correlations provide a powerful method for combining information from pairs of fields and separating them from noise and systematics. We derive a new Deconvolved Distribution Estimator that combines the useful properties of these two methods into one statistic. Using two example models of a toy Gaussian random field and a line intensity mapping survey, we demonstrate these properties quantitatively and show that the deconvolved distribution estimator can be used for inference. This new estimator can be applied to any pair of overlapping, non-Gaussian cosmological observations, including large-scale structure, the Sunyaev–Zeldovich effect, weak lensing, and many others.
COMAP Early Science. I. Overview Cleary, Kieran A.; Borowska, Jowita; Breysse, Patrick C. ...
Astrophysical journal/The Astrophysical journal,
07/2022, Letnik:
933, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
The CO Mapping Array Project (COMAP) aims to use line-intensity mapping of carbon monoxide (CO) to trace the distribution and global properties of galaxies over cosmic time, back to the ...Epoch of Reionization (EoR). To validate the technologies and techniques needed for this goal, a Pathfinder instrument has been constructed and fielded. Sensitive to CO(1–0) emission from
z
= 2.4–3.4 and a fainter contribution from CO(2–1) at
z
= 6–8, the Pathfinder is surveying 12 deg
2
in a 5 yr observing campaign to detect the CO signal from
z
∼ 3. Using data from the first 13 months of observing, we estimate
P
CO
(
k
) = −2.7 ± 1.7 × 10
4
μ
K
2
Mpc
3
on scales
k
= 0.051 −0.62 Mpc
−1
, the first direct three-dimensional constraint on the clustering component of the CO(1–0) power spectrum. Based on these observations alone, we obtain a constraint on the amplitude of the clustering component (the squared mean CO line temperature bias product) of
Tb
2
<
49
μ
K
2
, nearly an order-of-magnitude improvement on the previous best measurement. These constraints allow us to rule out two models from the literature. We forecast a detection of the power spectrum after 5 yr with signal-to-noise ratio (S/N) 9–17. Cross-correlation with an overlapping galaxy survey will yield a detection of the CO–galaxy power spectrum with S/N of 19. We are also conducting a 30 GHz survey of the Galactic plane and present a preliminary map. Looking to the future of COMAP, we examine the prospects for future phases of the experiment to detect and characterize the CO signal from the EoR.
Abstract
We present a detailed overview of the science goals and predictions for the Prime-Cam direct-detection camera–spectrometer being constructed by the CCAT-prime collaboration for dedicated use ...on the Fred Young Submillimeter Telescope (FYST). The FYST is a wide-field, 6 m aperture submillimeter telescope being built (first light in late 2023) by an international consortium of institutions led by Cornell University and sited at more than 5600 m on Cerro Chajnantor in northern Chile. Prime-Cam is one of two instruments planned for FYST and will provide unprecedented spectroscopic and broadband measurement capabilities to address important astrophysical questions ranging from Big Bang cosmology through reionization and the formation of the first galaxies to star formation within our own Milky Way. Prime-Cam on the FYST will have a mapping speed that is over 10 times greater than existing and near-term facilities for high-redshift science and broadband polarimetric imaging at frequencies above 300 GHz. We describe details of the science program enabled by this system and our preliminary survey strategies.
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