scholarly journals Intensity mapping cross-correlations II: HI halo models including shot noise

2018 ◽  
Vol 484 (1) ◽  
pp. 1007-1020 ◽  
Author(s):  
L Wolz ◽  
S G Murray ◽  
C Blake ◽  
J S Wyithe
Keyword(s):  
Shot Noise ◽  
Intensity Mapping ◽  
Cross Correlations

scholarly journals The atomic hydrogen content of the post-reionization Universe

2020 ◽  
Vol 493 (4) ◽  
pp. 5434-5455 ◽  
Author(s):  
Marta Spinelli ◽  
Anna Zoldan ◽  
Gabriella De Lucia ◽  
Lizhi Xie ◽  
Matteo Viel
Keyword(s):  
Galaxy Formation ◽  
Shot Noise ◽  
Atomic Hydrogen ◽  
Mass Function ◽  
Limiting Factor ◽  
History Plays ◽  
Local Universe ◽  
Intensity Mapping ◽  
The One ◽  
Halo Occupation Distribution

ABSTRACT We present a comprehensive analysis of atomic hydrogen (H i) properties using a semi-analytical model of galaxy formation and N-body simulations covering a large cosmological volume at high resolution. We examine the H i mass function and the H i density, characterizing both their redshift evolution and their dependence on hosting halo mass. We analyse the H i content of dark matter haloes in the local Universe and up to redshift z = 5, discussing the contribution of different galaxy properties. We find that different assembly history plays a crucial role in the scatter of this relation. We propose new fitting functions useful for constructing mock H i maps with halo occupation distribution techniques. We investigate the H i clustering properties relevant for future 21 cm intensity mapping (IM) experiments, including the H i bias and the shot-noise level. The H i bias increases with redshift and it is roughly flat on the largest scales probed. The scale dependence is found at progressively larger scales with increasing redshift, apart from a dip feature at z = 0. The shot-noise values are consistent with the ones inferred by independent studies, confirming that shot noise will not be a limiting factor for IM experiments. We detail the contribution from various galaxy properties on the H i power spectrum and their relation to the halo bias. We find that H i poor satellite galaxies play an important role at the scales of the one-halo term. Finally, we present the 21 cm signal in redshift space, a fundamental prediction to be tested against data from future radio telescopes such as Square Kilometre Array.

scholarly journals Studying high-z galaxies with [C ii]  intensity mapping

2019 ◽  
Vol 490 (2) ◽  
pp. 1928-1943 ◽  
Author(s):  
B Yue ◽  
A Ferrara
Keyword(s):  
Power Spectrum ◽  
Shot Noise ◽  
Signal To Noise Ratio ◽  
Contamination Level ◽  
Microwave Background ◽  
Noise Component ◽  
Intensity Mapping ◽  
Detection Depth ◽  
Infrared Background ◽  
Full Power

ABSTRACT We investigate the [C ii] line intensity mapping (IM) signal from galaxies in the Epoch of Reionization (EoR) to assess its detectability, the possibility to constrain the $L_{\rm C\,{\small II}}\!-\!{\rm SFR}$ relation, and to recover the [C ii] luminosity function (LF) from future experiments. By empirically assuming that ${\rm log}\,L_{\rm C\,{\small II}}={\rm log}\,A+\gamma {\rm SFR}\pm \sigma _\mathrm{ L}$, we derive the [C ii] LF from the observed UV LF, and the [C ii] IM power spectrum. We study the shot noise and the full power spectrum separately. Although, in general, the shot-noise component has a much higher signal-to-noise ratio than the clustering one, it cannot be used to put independent constraints on log A and γ. Full power spectrum measurements are crucial to break such degeneracy and reconstruct the [C ii] LF. In our fiducial survey S1 (inspired by CCAT-p/1000 h) at z ∼ 6, the shot-noise (clustering) signal is detectable for two (one) of the five considered $L_{\rm C\,{\small II}}\!-\!{\rm SFR}$ relations. The shot noise is generally dominated by galaxies with $L_{\rm C\,{\small II}}\gtrsim 10^{8}\!-\!10^{9}~ \mathrm{L}_\odot$ (MUV ∼ −20 to −22), already at reach of ALMA pointed observations. However, given the small field of view of such telescope, an IM experiment would provide unique information on the bright end of the LF. The detection depth of an IM experiment crucially depends on the (poorly constrained) $L_{\rm C\,{\small II}}\!-\!{\rm SFR}$ relation in the EoR. If the $L_{\rm C\,{\small II}}\!-\!{\rm SFR}$ relation varies in a wide log A–γ range, but still consistent with ALMA [C ii] LF upper limits, even the signal from galaxies with $L_{\rm C\,{\small II}}$ as faint as ∼107 L⊙ could be detectable. Finally, we consider the contamination by continuum foregrounds (cosmic infrared background, dust, cosmic microwave background) and CO interloping lines, and derive the requirements on the residual contamination level to reliably extract the [C ii] signal.

scholarly journals Impact of foregrounds on H i intensity mapping cross-correlations with optical surveys

2019 ◽  
Vol 488 (4) ◽  
pp. 5452-5472 ◽  
Author(s):  
Steven Cunnington ◽  
Laura Wolz ◽  
Alkistis Pourtsidou ◽  
David Bacon
Keyword(s):  
Neutral Hydrogen ◽  
Optical Data ◽  
Line Of Sight ◽  
Redshift Distribution ◽  
Intensity Mapping ◽  
Fast Independent Component Analysis ◽  
Cross Correlations ◽  
The Cross ◽  
The Impact ◽  
Optical Surveys

ABSTRACT The future of precision cosmology could benefit from cross-correlations between intensity maps of unresolved neutral hydrogen (H i) and more conventional optical galaxy surveys. A major challenge that needs to be overcome is removing the 21cm foreground emission that contaminates the cosmological H i signal. Using N-body simulations, we simulate H i intensity maps and optical catalogues that share the same underlying cosmology. Adding simulated foreground contamination and using state-of-the-art reconstruction techniques, we investigate the impacts that 21cm foregrounds and other systematics have on these cross-correlations. We find that the impact a Fast Independent Component Analysis 21cm foreground clean has on the cross-correlations with spectroscopic optical surveys with well-constrained redshifts is minimal. However, problems arise when photometric surveys are considered: We find that a redshift uncertainty σz ≥ 0.04 causes significant degradation in the cross-power spectrum signal. We diagnose the main root of these problems, which relates to arbitrary amplitude changes along the line of sight in the intensity maps caused by the foreground clean and suggest solutions that should be applicable to real data. These solutions involve a reconstruction of the line-of-sight temperature means using the available overlapping optical data along with an artificial extension to the H i data through redshift to address edge effects. We then put these solutions through a further test in a mock experiment that uses a clustering-based redshift estimation technique to constrain the photometric redshifts of the optical sample. We find that with our suggested reconstruction, cross-correlations can be utilized to make an accurate prediction of the optical redshift distribution.

scholarly journals A Model of Spectral Line Broadening in Signal Forecasts for Line-intensity Mapping Experiments

2021 ◽  
Vol 923 (2) ◽  
pp. 188
Author(s):  
Dongwoo T. Chung ◽  
Patrick C. Breysse ◽  
Håvard T. Ihle ◽  
Hamsa Padmanabhan ◽  
Marta B. Silva ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Shot Noise ◽  
Line Intensity ◽  
Line Emission ◽  
Power Spectra ◽  
Theoretical Treatment ◽  
Line Broadening ◽  
Primary Case ◽  
Millimetre Wave ◽  
Intensity Mapping

Abstract Line-intensity mapping observations will find fluctuations of integrated line emission are attenuated by varying degrees at small scales due to the width of the line emission profiles. This attenuation may significantly impact estimates of astrophysical or cosmological quantities derived from measurements. We consider a theoretical treatment of the effect of line broadening on both the clustering and shot-noise components of the power spectrum of a generic line-intensity power spectrum using a halo model. We then consider possible simplifications to allow easier application in analysis, particularly in the context of inferences that require numerous, repeated, fast computations of model line-intensity signals across a large parameter space. For the CO Mapping Array Project and the CO(1–0) line-intensity field at z ∼ 3 serving as our primary case study, we expect a ∼10% attenuation of the spherically averaged power spectrum on average at relevant scales of k ≈ 0.2–0.3 Mpc−1 compared to ∼25% for the interferometric Millimetre-wave Intensity Mapping Experiment targeting shot noise from CO lines at z ∼ 1–5 at scales of k ≳ 1 Mpc−1. We also consider the nature and amplitude of errors introduced by simplified treatments of line broadening and find that while an approximation using a single effective velocity scale is sufficient for spherically averaged power spectra, a more careful treatment is necessary when considering other statistics such as higher multipoles of the anisotropic power spectrum or the voxel intensity distribution.

scholarly journals DISSECTING THE HIGH-zINTERSTELLAR MEDIUM THROUGH INTENSITY MAPPING CROSS-CORRELATIONS

2016 ◽  
Vol 833 (2) ◽  
pp. 153 ◽  
Author(s):  
Paolo Serra ◽  
Olivier Doré ◽  
Guilaine Lagache
Keyword(s):  
Intensity Mapping ◽  
Cross Correlations

scholarly journals Intensity mapping cross-correlations: connecting the largest scales to galaxy evolution

2016 ◽  
Vol 458 (3) ◽  
pp. 3399-3410 ◽  
Author(s):  
L. Wolz ◽  
C. Tonini ◽  
C. Blake ◽  
J. S. B. Wyithe
Keyword(s):  
Galaxy Evolution ◽  
Intensity Mapping ◽  
Cross Correlations

scholarly journals The PAU survey: Lyα intensity mapping forecast

2020 ◽  
Author(s):  
Pablo Renard ◽  
Enrique Gaztanaga ◽  
Rupert Croft ◽  
Laura Cabayol ◽  
Jorge Carretero ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Narrow Band ◽  
Broad Band ◽  
Observation Time ◽  
Total Probability ◽  
Correlated Noise ◽  
Hydrodynamic Simulation ◽  
Intensity Mapping ◽  
Negative Results ◽  
Cross Correlations

Abstract In this work, we explore the application of intensity mapping to detect extended Lyα emission from the IGM via cross-correlation of PAUS images with Lyα forest data from eBOSS and DESI. Seven narrow-band (FWHM=13nm) PAUS filters have been considered, ranging from 455 to 515 nm in steps of 10 nm, which allows the observation of Lyα emission in a range 2.7 < z < 3.3. The cross-correlation is simulated first in an area of 100 deg2 (PAUS projected coverage), and second in two hypothetical scenarios: a deeper PAUS (complete up to iAB < 24 instead of iAB < 23, observation time x6), and an extended PAUS coverage of 225 deg2 (observation time x2.25). A hydrodynamic simulation of size 400 Mpc/h is used to simulate both extended Lyα emission and absorption, while the foregrounds in PAUS images have been simulated using a lightcone mock catalogue. Using an optimistic estimation of uncorrelated PAUS noise, the total probability of a non-spurious detection is estimated to be 1.8% and 4.5% for PAUS-eBOSS and PAUS-DESI , from a run of 1000 simulated cross-correlations with different realisations of instrumental noise and quasar positions. The hypothetical PAUS scenarios increase this probability to 15.3% (deeper PAUS) and 9.0% (extended PAUS). With realistic correlated noise directly measured from PAUS images, these probabilities become negligible. Despite these negative results, some evidences suggest that this methodology may be more suitable to broad-band surveys.

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