H i and cosmological constraints from intensity mapping, optical and CMB surveys

Pourtsidou, Alkistis; Bacon, David; Crittenden, Robert

doi:10.1093/mnras/stx1479

Cited by 75 publications

(91 citation statements)

References 74 publications

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“…We can therefore employ the Fisher matrix formalism [13] to forecast constraints on the HI abundance and bias along redshift. Using the aforementioned MeerKAT IM survey parameters, we find δ (Ω HI b HI )/(Ω HI b HI ) = 0.005 at z = 0.3 (L band) and [14]. These are more than one order of magnitude better than the currently available constraints from galaxy surveys, intensity mapping, and damped Lyman-α observations (see Table 2 in [15]).…”

Section: Hi Intensity Mapping With Meerkatmentioning

confidence: 78%

HI Intensity Mapping with MeerKAT

Pourtsidou¹

2018

Proceedings of MeerKAT Science: On the Pathway to the SKA — PoS(MeerKAT2016)

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Radio detections of the redshifted 21cm line with neutral hydrogen (HI) intensity mapping surveys can provide a new way to probe the evolving history of the Universe and tackle fundamental cosmological questions. Intensity mapping (IM) measures the fluctuations of the HI signal tracing the underlying matter distribution, and therefore can be used to reconstruct the matter power spectrum without the need to detect individual galaxies. This means that intensity mapping surveys can observe large volumes very fast, and give us access to large cosmological scales while providing excellent redshift information. We explore the possibility of performing such a survey with the South African MeerKAT radio telescope, which is a precursor to the Square Kilometre Array (SKA). We also propose to use cross-correlations between the MeerKAT intensity mapping survey and optical galaxy surveys, in order to mitigate important systematic effects and produce robust cosmological measurements. Our forecasts show that precise measurements of the HI clustering and lensing signals can be made in the near future. These can be used to constrain HI and cosmological parameters across a wide range of redshift.

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Section: Hi Intensity Mapping With Meerkatmentioning

confidence: 78%

HI Intensity Mapping with MeerKAT

Pourtsidou¹

2018

Proceedings of MeerKAT Science: On the Pathway to the SKA — PoS(MeerKAT2016)

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“…The assumed sky overlap is 500 deg 2 with 500 hr MeerKAT time. The forecast constraint is δ (Ω HI b HI r)/(Ω HI b HI r) = 0.02 [10]. Figure 1, bottom left, shows the expected (angle-averaged) signal and errors for a DES-like photometric sample [13], with 4000 deg 2 sky overlap and 4000 hr MeerKAT time.…”

Section: Detecting the Hi Intensity Mapping Signal With Meerkatmentioning

confidence: 98%

“…Assuming a ΛCDM expansion history, the only unknown in the power spectrum is the HI density times the bias, Ω HI (z)b HI (z). Employing a Fisher matrix analysis, [10] has shown that the constraints on this quantity will be more than one order of magnitude better than current constraints from galaxy surveys, intensity mapping, and damped Lyman-α observations [11]. Detection can also be achieved by cross-correlating with optical surveys [8].…”

Section: Detecting the Hi Intensity Mapping Signal With Meerkatmentioning

confidence: 99%

“…Figure 2 shows the expected signal to noise from BAO and RSD for different parameters, as a function of sky area and for a few observation times, at z = 0.4 and z = 1.0 (with a z bin of 0.1). The forecasting procedure follows the approach described in [14] (see also [10]). Looking in particular at the constraints on A, the overall BAO amplitude (left), we see that the signal to noise is better in the L-band.…”

Section: Baryon Acoustic Oscillations and Redshift Space Distortionsmentioning

confidence: 99%

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A Large Sky Survey with MeerKAT

Santos¹,

Bull²,

Camera³

et al. 2018

Proceedings of MeerKAT Science: On the Pathway to the SKA — PoS(MeerKAT2016)

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We discuss the ground-breaking science that will be possible with a wide area survey, using the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area Synoptic Survey). The current specifications of MeerKAT make it a great fit for cosmological applications, which require large volumes. In particular, a large survey over ∼ 4, 000 deg 2 for ∼ 4, 000 hours will potentially provide the first ever measurements of the baryon acoustic oscillations using the 21cm intensity mapping technique, with enough accuracy to impose constraints on the nature of dark energy. The combination with multi-wavelength data will give unique additional information, such as the first constraints on primordial non-Gaussianity using the multi-tracer technique, as well as a better handle on foregrounds and systematics. The survey will also produce a large continuum galaxy sample down to a depth of 5 µJy in L-band, unmatched by any other concurrent telescope, which will allow to study the large-scale structure of the Universe out to high redshifts. Finally, the same survey will supply unique information for a range of other science applications, including a large statistical investigation of galaxy clusters, and the discovery of rare high-redshift AGN that can be used to probe the epoch of reionization as well as produce a rotation measure map across a huge swathe of the sky. The MeerKLASS survey will be a crucial step on the road to using SKA1-MID for cosmological applications, as described in the top priority SKA key science projects.

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“…Pourtsidou et al (2016) found that this last case considerably improves the 21 cm lensing detection prospects and excellent results can be achieved within frequencies observed by SKA-Mid and MeerKAT. In general, cross-correlating the galaxy and HI densities at postEoR redshifts can be particularly useful for constraining HI and cosmological parameters and alleviate issues arising from systematic effects that are relevant for one type of survey but not the other (Masui et al 2013;Wolz et al 2016Wolz et al , 2017Pourtsidou et al 2017). …”

Section: Multi-band Constraintsmentioning

confidence: 99%

Simulations for 21 cm radiation lensing at EoR redshifts

Romeo

Metcalf

Pourtsidou

2017

Monthly Notices of the Royal Astronomical Society

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We introduce simulations aimed at assessing how well weak gravitational lensing of 21cm radiation from the Epoch of Reionization (z ∼ 8) can be measured by an SKA-like radio telescope. A simulation pipeline has been implemented to study the performance of lensing reconstruction techniques. We show how well the lensing signal can be reconstructed using the three-dimensional quadratic lensing estimator in Fourier space assuming different survey strategies. The numerical code introduced in this work is capable of dealing with issues that can not be treated analytically such as the discreteness of visibility measurements and the inclusion of a realistic model for the antennae distribution. This paves the way for future numerical studies implementing more realistic reionization models, foreground subtraction schemes, and testing the performance of lensing estimators that take into account the non Gaussian distribution of HI after reionization. If multiple frequency channels covering z ∼ 7 − 11.6 are combined, Phase 1 of SKA-Low should be able to obtain good quality images of the lensing potential with a total resolution of ∼ 1.6 arcmin. The SKA-Low Phase 2 should be capable of providing images with high-fidelity even using data from z ∼ 7.7−8.3. We perform tests aimed at evaluating the numerical implementation of the mapping reconstruction. We also discuss the possibility of measuring an accurate lensing power spectrum. Combining data from z ∼ 7 − 11.6 using the SKA2-Low telescope model, we find constraints comparable to sample variance in the range L < 1000, even for survey areas as small as 25 deg 2 .

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H i and cosmological constraints from intensity mapping, optical and CMB surveys

Cited by 75 publications

References 74 publications

HI Intensity Mapping with MeerKAT

HI Intensity Mapping with MeerKAT

A Large Sky Survey with MeerKAT

Simulations for 21 cm radiation lensing at EoR redshifts

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