Is patchy reionization an obstacle in detecting the primordial gravitational wave signal?

Mukherjee, Suvodip; Paul, S.; Choudhury, Tirthankar Roy

doi:10.1093/mnras/stz1002

Cited by 14 publications

(20 citation statements)

References 73 publications

(106 reference statements)

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“…Zel'dovich effect, patchy reionization effect (Smith & Ferraro 2017;Mukherjee et al 2019) and any extragalactic diffuse emission e.g. CIB in our analysis.…”

Section: Sky Modelingmentioning

confidence: 75%

$B$-mode forecast of CMB-Bh$\overline{a}$rat

Adak,

Sen,

Basak

et al. 2021

Preprint

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Exploring Cosmic History and Origins (ECHO), popularly known as 'CMB-Bharat', is a space mission that has been proposed to the Indian Space Research Organisation (ISRO) for the scientific exploitation of the Cosmic Microwave Background (CMB) at the next level of precision and accuracy. The quest for the CMB polarization B-mode signals, generated by inflationary gravitational waves in the very early universe, is one of the key scientific goals of its experimental design. This work studies the potential of the proposed ECHO instrumental configuration to detect the target tensor-to-scalar ratio r ∼ 10 −3 at 3σ significance level, which covers the predictions of a large class of inflationary models. We investigate the performance of two different component separation pipelines, NILC and Commander, for the measurement of r in presence of different physically motivated models of astrophysical foregrounds. For a simplistic foreground model (only polarized dust and synchrotron), both component separation pipelines can achieve the desired sensitivity of ECHO, i.e. σ(r = 0) ∼ (0.4 − 0.7) × 10 −3 . NILC performs better than Commander in terms of bias on recovered r for complex spectral models (power-law and curved power-law) of the synchrotron emission and complex dust models (dust decorrelation). Assuming 84% delensing, we can achieve an improvement of σ(r = 0) by approximately 50% as compared to the results obtained for the same configuration without any lensing correction.

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“…Zel'dovich effect, patchy reionization effect (Smith & Ferraro 2017;Mukherjee et al 2019) and any extragalactic diffuse emission e.g. CIB in our analysis.…”

Section: Sky Modelingmentioning

confidence: 75%

$B$-mode forecast of CMB-Bh$\overline{a}$rat

Adak,

Sen,

Basak

et al. 2021

Preprint

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“…The strength of the signal depends on the integrated electron density fluctuation during the EoR. Reionization driven by massive halos can lead to large spatial fluctuations in electron density (Mukherjee et al 2019). Also for a longer (or shallower) duration of reionization, the net integrated contribution to B-mode polarization should be more (or less).…”

Section: Motivation: Connecting the Physics Of Eor With Cosmological ...mentioning

confidence: 99%

“…RMS denotes the quadrupole temperature variance, which is considered to be 22 µK over the redshift range of reionization and j l (kχ) are the spherical Bessel functions. This signal is dominant at large angular scales and can be a source of contamination to the primordial B-mode polarization signal (Mortonson & Hu 2007;Mukherjee et al 2019;Roy et al 2020). In our previous study (Mukherjee et al 2019), we used semi-numerical simulations of the EoR to show that there can be up to 30% bias in the value of tensor to scalar ratio r = 0.001 measured by the upcoming CMB probes of the B-mode polarization and can also lead to an increase in the error-bar on r.…”

Section: Secondary Cmb Polarization During the Eormentioning

confidence: 99%

“…Additional fluctuations due to patchy reionization can also bias the inferred value of the amplitude of primordial gravitational waves denoted by r (tensor to scalar ratio) (Mortonson & Hu 2007;Mukherjee et al 2019). In our previous study from simulations (Mukherjee et al 2019), we have shown that the bias in the value of r gets stronger for reionization driven by massive halos and can be comparable with the error bar of the upcoming CMB missions (see also Roy et al 2020). A joint estimation of the kSZ signal, Emode polarization and B-mode polarization signal will be also useful to mitigate the contamination in the primordial B-mode polarization signal.…”

Section: Impact On B-mode Polarization Power Spectrummentioning

confidence: 99%

“…The patchy reionization also gives rise to secondary B-mode polarization and leaves an imprint on the measurements of the primordial B-mode polarization (Hu 2000;Santos et al 2003;Zahn et al 2005;McQuinn et al 2005;Mortonson & Hu 2007;Su et al 2011). In a previous paper (Mukherjee et al 2019), we have studied this effect in detail using simulations and estimated the patchy reionization contamination in the primordial B-mode polarization signal.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inevitable imprints of patchy reionization on the cosmic microwave background anisotropy

Paul,

Mukherjee,

Choudhury

2020

Preprint

Self Cite

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Reionization of the cosmic neutral hydrogen by the first stars in the Universe is an inhomogeneous process which produces spatial fluctuations in free electron density. These fluctuations lead to observable signatures in cosmological probes like the cosmic microwave background (CMB). We explore the effect of the electron density fluctuations on CMB using photon-conserving semi-numerical simulations of reionization named SCRIPT. We show that the amplitude of the kinematic Sunyaev-Zeldovich (kSZ) and B-mode polarization signal depends on the electron density fluctuations along with the dependence on mid-point and extent of the reionization history. Motivated by this finding, we provide new scaling relations for the amplitude of kSZ and B-mode polarization signal which can capture the effects arising from the mean optical depth, width of reionization, and spatial fluctuations in the electron density. We show that the amplitude of the kSZ and B-mode polarization signal exhibits different dependency on the width of reionization and spatial fluctuations, and hence a joint study of these CMB probes will be able to break the degeneracy. By combining external datasets from 21 cm measurements, the degeneracy can be further lifted by directly exploring the sizes of the ionized regions.

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Revised estimates of CMB B-mode polarization induced by patchy reionization

Roy

Kulkarni

Meerburg

et al. 2021

J. Cosmol. Astropart. Phys.

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The search for primordial gravitational waves through the B-mode polarization pattern in the CMB is one of the major goals of current and future CMB experiments. Besides foregrounds, a potential hurdle in this search is the anisotropic secondary B-mode polarization generated by the scattering of CMB photons off free electrons produced during patchy cosmological reionization. Robust predictions of these secondary anisotropies are challenging because of uncertainties in the reionization history. In this paper we revise estimates of the reionization-induced B-mode signal by incorporating recent advances in the understanding of reionization through observations of the Lyman-α forest. To derive these B-mode estimates, we use high-dynamic-range radiative transfer simulations of reionization that are calibrated to the Lyα data. These simulations are also consistent with a variety of other high-redshift observations. We find that around multipoles ≈ 100, reionization induces B-mode power with ( + 1)C BB /2π ≈ 4 × 10 −6 µK 2 . This secondary signal is thus at the level of the primordial signal with the tensor-to-scalar ratio r < 10 −4 , and can increase by a factor of ∼ 50 if reionization is sourced by highly clustered sources residing in haloes with mass of ∼ 10 11 M . Our findings suggest that the contribution of patchy reionization to the search for primordial gravitational waves is unlikely to be a concern for currently planned CMB experiments.

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Is patchy reionization an obstacle in detecting the primordial gravitational wave signal?

Cited by 14 publications

References 73 publications

$B$-mode forecast of CMB-Bh$\overline{a}$rat

$B$-mode forecast of CMB-Bh$\overline{a}$rat

Inevitable imprints of patchy reionization on the cosmic microwave background anisotropy

Revised estimates of CMB B-mode polarization induced by patchy reionization

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