The nature of dark matter is a longstanding mystery in cosmology, which can be studied with laboratory or collider experiments, as well as astrophysical and cosmological observations. In this work, we propose realistic and efficient strategies to detect radiative products from dark-matter decays with line-intensity mapping (LIM) experiments. This radiation will behave as a line interloper for the atomic and molecular spectral lines targeted by LIM surveys. The most distinctive signatures of the contribution from dark-matter radiative decays are an extra anisotropy on the LIM power spectrum due to projection effects, as well as a narrowing and a shift towards higher intensities of the voxel intensity distribution. We forecast the minimum rate of decays into two photons that LIM surveys will be sensitive to as function of the dark-matter mass in the range $\sim 10^{-6}-10$ eV, and discuss how to reinterpret such results for dark matter that decays into a photon and another particle. We find that both the power spectrum and the voxel intensity distribution are expected to be very sensitive to the dark-matter contribution, with the voxel intensity distribution being more promising for most experiments considered. Interpreting our results in terms of the axion, we show that LIM surveys will be extremely competitive to detect its decay products, improving several orders of magnitudes (depending on the mass) the sensitivity of laboratory and astrophysical searches, especially in the mass range $\sim 1-10$ eV.
One of the toughest challenges in modern cosmology is to probe the small scales $k \sim 0.5\,$Mpc$^{-1}$ in the matter power spectrum and clustering. We show that such small scales will be accessible via upcoming line-intensity mapping surveys, with carbon monoxide (CO) emission from star-forming galaxies at high redshifts as an example. While these galaxies cannot be individually detected and the two-point correlations of the intensity fluctuation maps is not accessible at these scales, the voxel intensity distribution (VID) of the highly non-Gaussian intensity maps is sensitive to the integr…
The power spectrum and the voxel intensity distribution (VID) are two of the main proposed summary statistics to study line-intensity maps. We reformulate the derivation of the VID in terms of the local overdensities and derive for the first time an analytic covariance between the VID and the line-intensity mapping power spectrum. We study the features of this covariance for different experimental setups and show that we can recover similar results to simulation-based covariances. With this formalism, we also compute the cosmic variance contribution the VID uncertainty, which we find to be sub…
The purpose of line-intensity mapping (IM), an emerging tool for extragalactic astronomy and cosmology, is to measure the integrated emission along the line of sight from spectral lines emitted from galaxies and the intergalactic medium. The observed frequency of the line then provides a distance determination allowing the three-dimensional distribution of the emitters to be mapped. Here we discuss the possibility to use these measurements to seek radiative decays or annihilations from dark-matter particles. The photons from monoenergetic decays will be correlated with the mass distribution, w…
Line intensity mapping is rapidly gaining prominence as a tool to understand galaxy evolution and cosmology at high redshift. However, the standard power spectrum analysis for these surveys suffers from a tight degeneracy between the overall mean line intensity and the bias of the emitting galaxies. We outline a new formalism for the Voxel Intensity Distribution (VID), a one-point statistic which is known to contain information beyond the power spectrum. We use this new calculation to show for the first time that the VID can be used to break this key degeneracy in intensity mapping data.
We explore the potential of using intensity mapping surveys (MeerKAT, SKA) and optical galaxy surveys (DES, LSST) to detect HI clustering and weak gravitational lensing of 21cm emission in auto- and cross-correlation. Our forecasts show that high precision measurements of the clustering and lensing signals can be made in the near future using the intensity mapping technique. Such studies can be used to test the intensity mapping method, and constrain parameters such as the HI density $Ω_{\rm HI}$, the HI bias $b_{\rm HI}$ and the galaxy-HI correlation coefficient $r_{\rm HI-g}$.
The cosmological X-ray emission associated to the possible radiative decay of sterile neutrinos is composed by a collection of lines at different energies. For a given mass, each line corresponds to a given redshift. In this work, we cross correlate such line emission with catalogs of galaxies tracing the dark matter distribution at different redshifts. We derive observational prospects by correlating the X-ray sky that will be probed by the eROSITA and Athena missions with current and near future photometric and spectroscopic galaxy surveys. A relevant and unexplored fraction of the parameter…
We explore the possibility of performing an HI intensity mapping survey with the South African MeerKAT radio telescope, which is a precursor to the Square Kilometre Array (SKA). We propose to use cross-correlations between the MeerKAT intensity mapping survey and optical galaxy surveys, in order to mitigate systematic effects and produce robust cosmological measurements. Our forecasts show that precise measurements of the HI signal can be made in the near future. These can be used to constrain HI and cosmological parameters across a wide range of redshift.
Recent studies using New Horizons LORRI images have returned the most precise measurement of the cosmic optical background to date, yielding a flux that exceeds that expected from deep galaxy counts by roughly a factor of two. We investigate whether this excess, detected at $\sim 4σ$ significance, is due to axion-like dark matter that decays to monoenergetic photons. We compute the spectral energy distribution from such decays and the contribution to the flux measured by LORRI. Assuming that axion-like particles make up all of the dark matter, the parameter space unconstrained to date that exp…
We study the possibility to use line-intensity mapping (LIM) to seek photons from the radiative decay of neutrinos in the cosmic neutrino background. The Standard Model prediction for the rate for these decays is extremely small, but it can be enhanced if new physics increases the neutrino electromagnetic moments. The decay photons will appear as an interloper of astrophysical spectral lines. We propose that the neutrino-decay line can be identified with anisotropies in LIM clustering and also with the voxel intensity distribution. Ongoing and future LIM experiments will have -- depending on t…
21cm intensity mapping is a novel approach aimed at measuring the power spectrum of density fluctuations and deducing cosmological information, notably from the Baryonic Acoustic Oscillations (BAO). We give an update on the progress of BAO from Integrated Neutral Gas Observations (BINGO) which is a single dish intensity mapping project. First we explain the basic ideas behind intensity mapping concept before updating the instrument design for BINGO. We also outline the survey we plan to make and its projected science output including estimates of cosmological parameters.
The 21-cm and Lyman Alpha lines are the dominant line-emission spectral features at opposite ends of the spectrum of hydrogen. Each line can be used to create three dimensional intensity maps of large scale structure. The sky brightness at low redshift due to Lyman Alpha emission is estimated to be 0.4 Jy/Steradian, which is brighter than the zodiacal light foreground.
We study a model of interacting dark matter and dark energy, in which the two components are coupled. We calculate the predictions for the 21-cm intensity mapping power spectra, and forecast the detectability with future single-dish intensity mapping surveys (BINGO, FAST and SKA-I). Since dark energy is turned on at $z\sim 1$, which falls into the sensitivity range of these radio surveys, the HI intensity mapping technique is an efficient tool to constrain the interaction. By comparing with current constraints on dark sector interactions, we find that future radio surveys will produce tight an…
Imaging surveys of galaxies will have a high number density and angular resolution yet a poor redshift precision. Intensity maps of neutral hydrogen (HI) will have accurate redshift resolution yet will not resolve individual sources. Using this complementarity, we show how the clustering redshifts approach, proposed for spectroscopic surveys can also be used in combination with intensity mapping observations to calibrate the redshift distribution of galaxies in an imaging survey and, as a result, reduce uncertainties in photometric redshift measurements. We show how the intensity mapping surve…
We present a code to generate mock observations of 21 cm intensity mapping experiments. The emphasis of the code is on reducing the computational cost of running a full-blown simulation, trading computational time for accuracy. The code can be used to generate independent realizations of the cosmological signal and foregrounds, which are necessary, for instance, in order to obtain realistic forecasts for future intensity mapping experiments. The code is able to reproduce the correct angular and radial clustering pattern for the cosmological signal, including redshift-space distortions, lightco…
We forecast ability of dedicated 21 cm intensity mapping experiments to constraint primordial non-Gaussianity using power spectrum and bispectrum. We model the signal including the non-linear biasing expansion using a generalized halo model approach. We consider the importance of foreground filtering scale and of the foreground wedge. We find that the current generation intensity mapping experiments like CHIME do not posses sufficient sensitivity to be competitive with the existing limits. On the other hand, upcoming experiments like HIRAX can improve the current constraints and the proposed P…
The nature of the most abundant components of the Universe, dark energy and dark matter, is still to be uncovered. I tackle this subject considering a novel cosmological probe: the neutral hydrogen emitted 21cm radiation, observed with the intensity mapping technique. I analyse competitive and realistic dark energy and dark matter models and show how they produce distinctive and detectable effects on the 21cm signal. Moreover, I provide radio telescope forecasts showing how these models will be distinguishable in an unprecedented way.
Spectral line intensity mapping has been proposed as a promising tool to efficiently probe the cosmic reionization and the large-scale structure. Without detecting individual sources, line intensity mapping makes use of all available photons and measures the integrated light in the source confusion limit, to efficiently map the three-dimensional matter distribution on large scales as traced by a given emission line. One particular challenge is the separation of desired signals from astrophysical continuum foregrounds and line interlopers. Here we present a technique to extract large-scale stru…
We present projected constraints on modified gravity models from the observational technique known as 21 cm intensity mapping, where cosmic structure is detected without resolving individual galaxies. The resulting map is sensitive to both BAO and weak lensing, two of the most powerful cosmological probes. It is found that a 200 m x 200 m cylindrical telescope, sensitive out to z=2.5, would be able to distinguish DGP from most dark energy models, and constrain the Hu & Sawicki f(R) model to |f_{R0}| < 9*10^(-6) at 95% confidence. The latter constraint makes extensive use of the lensing spectru…
Constraining the properties of Population III (Pop III) stars will be very challenging because they reside in small galaxies at high redshift which will be difficult to directly detect. In this paper, we suggest that intensity mapping may be a promising method to study Pop III stars. Intensity mapping is a technique proposed to measure large-scale fluctuations of galaxy line emission in three dimensions without resolving individual sources. This technique is well suited for observing many faint galaxies because it can measure their cumulative emission even if they cannot be directly detected. …
Intensity mapping has attracted significant interest as an approach to measure the properties of the interstellar medium in typical galaxies at high redshift. Intensity mapping measures the statistics of surface brightness as a function of frequency, making it sensitive not only to all line emission of interest but also radiation from all other sources. Significant effort has gone into developing approaches that reject foreground contamination. Additionally, the target galaxies have multiple sources of emission that can complicate the interpretation of the line brightness. We describe the prob…
21cm intensity mapping experiments aim to observe the diffuse neutral hydrogen (HI) distribution on large scales which traces the Cosmic structure. The Square Kilometre Array (SKA) will have the capacity to measure the 21cm signal over a large fraction of the sky. However, the redshifted 21cm signal in the respective frequencies is faint compared to the Galactic foregrounds produced by synchrotron and free-free electron emission. In this article, we review selected foreground subtraction methods suggested to effectively separate the 21cm signal from the foregrounds with intensity mapping simul…
In this paper, we study lensing of 21cm intensity mapping (IM). Like in the cosmic microwave background (CMB), there is no first order lensing in intensity mapping. The first effects in the power spectrum are therefore of second and third order. Despite this, lensing of the CMB power spectrum is an important effect that needs to be taken into account, which motivates the study of the impact of lensing on the IM power spectrum. We derive a general formula up to third order in perturbation theory including all the terms with two derivatives of the gravitational potential, i.e. the dominant terms…
Line intensity mapping offers a new avenue for constraining cosmological parameters in the high redshift Universe. However measurements of the growth of structure, a sensitive probe of gravity, are affected by a well known degeneracy with astrophysical parameters, encoded in the mean brightness temperature of the specific line. In this work we show how to break this degeneracy, to a level that could allow constraints of the amplitude of cosmological fluctuations at the percent level, using information in the mildly non-linear regime of structure formation as described by Lagrangian Perturbatio…
It has been proposed recently that the SKA1-MID could be used to conduct an HI intensity mapping survey that could rival upcoming Stage IV dark energy surveys. However, measuring the weak HI signal is expected to be very challenging due to contaminations such as residual Galactic emission, RFI, and instrumental 1/f noise. Modelling the effects of these contaminants on the cosmological HI signal requires numerical end-to-end simulations. Here we present how 1/f noise within the receiver can double the effective uncertainty of an SKA-like survey to HI on large angular scales (l < 50).
Precision cosmology requires accurate galaxy redshifts, but next generation optical surveys will observe unprecedented numbers of resolved galaxies, placing strain on the amount of spectroscopic follow-up required. We show how useful information can be gained on the redshift distributions of optical galaxy samples from spatial cross-correlations with intensity maps of unresolved HI (21cm) spectral line emission. We construct a redshift distribution estimator, which we test using simulations. We utilise the S3-SAX catalogue which includes HI emission information for each galaxy, which we use to…
We forecast constraints on neutral hydrogen (HI) and cosmological parameters using near-term intensity mapping surveys with instruments such as BINGO, MeerKAT, and the SKA, and Stage III and IV optical galaxy surveys. If foregrounds and systematic effects can be controlled - a problem which becomes much easier in cross-correlation - these surveys will provide exquisite measurements of the HI density and bias, as well as measurements of the growth of structure, the angular diameter distance, and the Hubble rate, over a wide range of redshift. We also investigate the possibility of detecting the…
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-int…
21 cm intensity mapping has arisen as a powerful probe of the high-redshift universe, but its potential is limited by extremely bright foregrounds and high source confusion. In this Letter, we propose a new analysis which can help solve both problems. From the combination of an intensity map with an overlapping galaxy survey we construct a new one-point statistic which is unbiased by foregrounds and contains information left out of conventional analyses. We show that our method can measure the HI mass function with unprecedented precision using observations similar to recent 21 cm detections.
The intensity mapping of Ly-alpha emission during the epoch of reionization (EoR) will be contaminated by foreground emission lines from lower redshifts. We calculate the mean intensity and power spectrum of Ly-alpha emission at z~7, and estimate the uncertainties according to the relevant astrophysical processes. We find that the low-redshift emission lines from 6563 A H-alpha, 5007 A [OIII] and 3727 A [OII] will be the strong contaminants on the observed Ly-alpha power spectrum. We make use of both the star formation rate (SFR) and luminosity functions (LF) to estimate the mean intensity and…
We investigate the possibility of testing Einstein's general theory of relativity (GR) and the standard cosmological model via the $E_{\rm G}$ statistic using neutral hydrogen (HI) intensity mapping. We generalise the Fourier space estimator for $E_{\rm G}$ to include HI as a biased tracer of matter and forecast statistical errors using HI clustering and lensing surveys that can be performed in the near future, in combination with ongoing and forthcoming optical galaxy and Cosmic Microwave Background (CMB) surveys. We find that fractional errors $< 1\%$ in the $E_{\rm G}$ measurement can be ac…
We consider the potential for line intensity mapping (IM) experiments to measure the baryon acoustic oscillations (BAO) from 3 < z < 6. This would constrain the expansion history in a redshift range that is currently unexplored. We calculate the map depths that future IM experiments targeting the CO(1-0) rotational transition line and [CII] ionized carbon fine-structure line would need to achieve in order to measure the BAO. We find that near-future IM experiments could constrain the BAO scale to 5% or better depending on CO/[CII] model amplitude. This measurement is at a precision that could …
BINGO is a concept for performing a 21cm intensity mapping survey using a single dish telescope. We briefly discuss the idea of intensity mapping and go on to define our single dish concept. This involves a \sim 40 m dish with an array of \sim 50 feed horns placed \sim 90 m above the dish using a pseudo-correlation detection system based on room temperature LNAs and one of the celestial poles as references. We discuss how such an array operating between 960 and 1260 MHz could be used to measure the acoustic scale to 2.4% over the redshift range 0.13<z<0.48 in around 1 year of on-source integra…
We present a quantitative model of Lyman-alpha (Ly-alpha) emission throughout cosmic history and determine the prospects for intensity mapping of spatial fluctuations in the Ly-alpha signal. Since i) our model assumes at z>6 the minimum star formation required to sustain reionization and ii) is based at z<6 on a luminosity function extrapolated from the few observed bright Ly-alpha emitters, this should be considered a lower limit. Mapping the line emission allows probes of reionization, star formation, and large-scale structure (LSS) as a function of redshift. While Ly-alpha emission during r…
Intensity mapping has been attracting increasing interest as a way to study galaxy evolution and the large scale structure of the Universe. Instead of detecting individual galaxies, we measure the integrated emission from a volume of the universe. Contrary to galaxy surveys, it includes light from the faintest objects in the cosmic web. We will start this overview by introducing line intensity mapping and review its current observational status. We will enumerate the most prominent emission lines for intensity mapping and discuss how to model their observed signal. The prospects of using this …
We present the science enabled by cross-correlations of the SKA1-LOW 21-cm EoR surveys with other line mapping programs. In particular, we identify and investigate potential synergies with planned programs, such as the line intensity mapping of redshifted CO rotational lines, [CII] and Ly-$α$ emissions during reionization. We briefly describe how these tracers of the star-formation rate at $z \sim 8$ can be modeled jointly before forecasting their auto- and cross-power spectra measurements with the nominal 21cm EoR survey. The use of multiple line tracers would be invaluable to validate and en…
We address the problem of line confusion in intensity mapping surveys and explore the possibility to mitigate line foreground contamination by progressively masking the brightest pixels in the observed map. We consider experiments targeting CO(1-0) at $z=3$, Ly$α$ at $z=7$, and CII at $z=7$, and use simulated intensity maps, which include both clustering and shot noise components of the signal and possible foregrounds, in order to test the efficiency of our method. We find that for CO and Ly$α$ it is quite possible to remove most of the foreground contribution from the maps via only 1%-3% pixe…
Molecular hydrogen is now understood to be the main coolant of the primordial gas clouds leading to the formation of the very first stars and galaxies. The line emissions associated with molecular hydrogen should then be a good tracer of the matter distribution at the onset of reionization of the universe. Here we propose intensity mapping of H2 line emission in rest-frame mid-infrared wavelengths to map out the spatial distribution of gas at redshifts z > 10. We calculate the expected mean intensity and clustering power spectrum for several H2 lines. We find that the 0-0S(3) rotational line a…
Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3-D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3-D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linea…
Constraints on primordial non-Gaussianity (PNG) will shed light on the origin of primordial fluctuations and the physics of the early universe. The intensity mapping technique is a promising probe of structure formation on large scales; at high redshifts, it can provide complementary information to other cosmological probes. We explore the potential of future wide-field [CII] and CO intensity mapping surveys in constraining PNG of the local shape, which induces a distinct, scale-dependent correction to the line bias. We explore the parameter space of CO and [CII] survey designs that can achiev…
We study how 21 cm intensity mapping can be used to measure gravitational lensing over a wide range of redshift. This can extend weak lensing measurements to higher redshifts than are accessible with conventional galaxy surveys. We construct a convergence estimator taking into account the discreteness of galaxies and calculate the expected noise level as a function of redshift and telescope parameters. At $z \sim 2-3$ we find that a telescope array with a collecting area $\sim 0.2 \, {\rm km}^2$ spread over a region with diameter $\sim 2 \, {\rm km}$ would be sufficient to measure the converge…
Using the galaxy catalog built from ELUCID N-body simulation and the semi-analytical galaxy formation model, we have built a mock HI intensity mapping map. We have implemented the Finger-of-God (FoG) effect in the map by considering the galaxy HI gas velocity dispersion. By comparing the HI power spectrum in the redshift space with the measurement from IllustrisTNG simulation, we have found that such FoG effect can explain the discrepancy between current mock map built from N-body simulation and Illustris TNG simulation. Then we built a parameter-free FoG model and a shot-noise model to calcul…
The cross-correlation of a foreground density field with two different background convergence fields can be used to measure cosmographic distance ratios and constrain dark energy parameters. We investigate the possibility of performing such measurements using a combination of optical galaxy surveys and HI intensity mapping surveys, with emphasis on the performance of the planned Square Kilometre Array (SKA). Using HI intensity mapping to probe the foreground density tracer field and/or the background source fields has the advantage of excellent redshift resolution and a longer lever arm achiev…
In modern cosmology, an important task is investigating whether there exists a signal of modified gravity in the universe. Due to the limited resolutions and sensitivities of facilities, current observations can not detect any signal of modified gravity. As a consequence, it is urgent to predict the constraining power of future cosmological surveys on modified gravity. We constrain the Hu-Sawicki $f(R)$ gravity with eight future mainstream probes encompassing 21 cm intensity mapping, HI galaxy, cosmic microwave background, optical galaxy, weak lensing, galaxy clustering, type Ia supernovae and…
HI intensity mapping (IM) is an exciting new probe that could revolutionize the future of cosmology. However, the relative faintness of the HI signal when compared to foregrounds of astrophysical or terrestrial origin will make HI IM extremely challenging. The imprint of these foregrounds may result in systematic errors in the recovered cosmological signal. We discuss an IM simulation pipeline developed at Manchester that can introduce systematic errors at the TOD level in order to help assess their impact. We will present results for two potential sources of systematics for HI IM surveys: 1/f…
In the last decade, it has become clear that the dust-enshrouded star formation contributes significantly to early galaxy evolution. Detection of dust is therefore essential in determining the properties of galaxies in the high-redshift universe. This requires observations at the (sub-)millimeter wavelengths. Unfortunately, sensitivity and background confusion of single dish observations on the one hand, and mapping efficiency of interferometers on the other hand, pose unique challenges to observers. One promising route to overcome these difficulties is intensity mapping of fluctuations which …
Understanding the formation and evolution of the Universe is crucial for cosmological studies, and the line intensity mapping provides a powerful tool for this kind of study. We propose to make use of multipole moments of redshift-space line intensity power spectrum to constrain the cosmological and astrophysical parameters, such as the equation of state of dark energy, massive neutrinos, primordial non-Gaussianity, and star formation rate density. As an example, we generate mock data of multipole power spectra for H-alpha 6563AA, [OIII] 5007AA and [OII] 3727AA measured by SPHEREx experiment a…
Upcoming cosmological intensity mapping surveys will open new windows on the Universe, but they must first overcome a number of significant systematic effects, including polarization leakage. We present a formalism that uses scan strategy information to model the effect of different instrumental systematics on the recovered cosmological intensity signal for `single-dish' (autocorrelation) surveys. This modelling classifies different systematics according to their spin symmetry, making it particularly relevant for dealing with polarization leakage. We show how to use this formalism to calculate…
We discuss the possibility of studying diffuse baryon distributions with kinematic Sunyaev-Zel'dovich (kSZ) effect by correlating cosmic microwave background (CMB) temperature fluctuations with density fluctuations from 21\,cm intensity mapping (IM). The biggest challenge for the cross-correlation is the loss of large-scale information in IM, due to foregrounds and the zero spacing problem of interferometers. We apply the tidal reconstruction algorithm to restore the lost large-scale modes, which increases the correlation by more than a factor of three. With the predicted foreground level, we …
We investigate the feasibility of measuring the effects of peculiar velocities in large-scale structure using the dipole of the redshift-space cross-correlation function. We combine number counts of galaxies with brightness-temperature fluctuations from 21cm intensity mapping, demonstrating that the dipole may be measured at modest significance ($\lesssim 2σ$) by combining the upcoming radio survey CHIME with the future redshift surveys of DESI and Euclid. More significant measurements ($\lesssim~10σ$) will be possible by combining intensity maps from the SKA with these of DESI or Euclid, and …
We present a study of the feasibility of an intensity-mapping survey targeting the 115 GHz CO(1-0) rotational transition at $z\sim3$. We consider four possible models and estimate the spatial and angular power spectra of CO fluctuations predicted by each of them. The frequency bandwidths of most proposed CO intensity mapping spectrographs are too small to use the Limber approximation to calculate the angular power spectrum, so we present an alternative method for calculating the angular power spectrum. The models we consider span two orders of magnitude in signal amplitude, so there is a signi…
We quantify the prospects for using emission lines from rotational transitions of the CO molecule to perform an `intensity mapping' observation at high redshift during the Epoch of Reionization (EoR). The aim of CO intensity mapping is to observe the combined CO emission from many unresolved galaxies, to measure the spatial fluctuations in this emission, and use this as a tracer of large scale structure at very early times in the history of our Universe. This measurement would help determine the properties of molecular clouds -- the sites of star formation -- in the very galaxies that reionize…
We investigate the prospects of measuring the cosmic magnification effect by cross-correlating neutral hydrogen intensity mapping (HI IM) maps with background optical galaxies. We forecast the signal-to-noise ratio for HI IM data from SKA1-MID and HIRAX, combined with LSST photometric galaxy samples. We find that, thanks to their different resolutions, SKA1-MID and HIRAX are highly complementary in such an analysis. We predict that SKA1-MID can achieve a detection with a signal-to-noise ratio of $\sim 15$ on a multipole range of $\ell \lesssim 200$, while HIRAX can reach a signal-to-noise rati…
Line-Intensity Mapping is an emerging technique which promises new insights into the evolution of the Universe, from star formation at low redshifts to the epoch of reionization and cosmic dawn. It measures the integrated emission of atomic and molecular spectral lines from galaxies and the intergalactic medium over a broad range of frequencies, using instruments with aperture requirements that are greatly relaxed relative to surveys for single objects. A coordinated, comprehensive, multi-line intensity-mapping experimental effort can efficiently probe over 80% of the volume of the observable …
Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (HI) is now regarded as one the most promising tools for cosmological investigation in the coming decades. Here, we investigate, for the first time, extensions of the standard cosmological model, such as modified gravity and primordial non-Gaussianity, taking self-consistently into account the present constraints on the astrophysics of HI clustering in the treatment of the brightness temperature fluctuations. To understand the boundaries within which results thus obtained can be considered reliable, we examine the robus…
