Can Primordial Magnetic Fields be the Origin of the BICEP2 Data?

Bonvin, Camille; Durrer, Ruth; Maartens, Roy

doi:10.1103/physrevlett.112.191303

Cited by 55 publications

(71 citation statements)

References 42 publications

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“…This paper demonstrates for the first time lensing reconstruction using B modes in the intermediate multipole range from the BK14 B-mode spectrum starts to place constraints on any alternative sources of B modes at these angular scales, such as cosmic strings (e.g., Seljak & Slosar 2006;Pogosian & Wyman 2008), primordial magnetic fields (e.g., Shaw & Lewis 2010;Bonvin et al 2014), and cosmic birefringence induced by interaction between a massless pseudo-scalar field and photons (e.g., Pospelov et al 2009;Lee et al 2015;POLARBEAR Collaboration 2015). The calculation of formal quantitative constraints is rather involved and depends on the assumed statistical properties of the alternative B-mode sources.…”

Section: Discussionmentioning

confidence: 99%

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Ade¹,

Ahmed²,

Aikin³

et al. 2016

ApJ

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We present measurements of polarization lensing using the 150 GHz maps, which include all data taken by the BICEP2andKeck Array Cosmic Microwave Background polarization experiments up to and including the 2014 observing season (BK14). Despite their modest angular resolution (~ 0 . 5), the excellent sensitivity (∼3μK-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales (  ℓ 700). From the auto-spectrum of the reconstructed potential, we measure an amplitude of the spectrum to be) and reject the no-lensing hypothesis at s 5.8 , which is the highest significance achieved to date using an EB lensing estimator. Taking ). We perform a series of null tests and consistency checks to show that these results are robust against systematics and are insensitive to analysis choices. These results unambiguously demonstrate that the B modes previously reported by BICEP/Keck at intermediate angular scales350) are dominated by gravitational lensing. The good agreement between the lensing amplitudes obtained from the lensing reconstruction and B-mode spectrum starts to place constraints on any alternative cosmological sources of B modes at these angular scales.

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Section: Discussionmentioning

confidence: 99%

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Ade¹,

Ahmed²,

Aikin³

et al. 2016

ApJ

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Section: +007mentioning

confidence: 99%

“…However, the BI-CEP2 result is in tension with Planck limits on standard inflationary models [5], and thus alternative explanations may be required. In principle, magnetic fields generated during inflation can produce the required B-mode, for a suitable range of energy scales of inflation [5]. Moreover, the existence of the fluctuations of cosmological birefringence can give rise to CMB B-mode polarization that fits BICEP2 data with r < 0.11, and no running of the scalar spectral index [6].…”

Section: +007mentioning

confidence: 99%

Nonminimal torsion-matter coupling extension off(T)gravity

et al. 2014

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We construct an extension of f (T ) gravity with the inclusion of a non-minimal torsion-matter coupling in the action. The resulting theory is a novel gravitational modification, since it is different from both f (T ) gravity, as well as from the nonminimal curvature-matter-coupled theory. The cosmological application of this new theory proves to be very interesting. In particular, we obtain an effective dark energy sector whose equation-of-state parameter can be quintessence-or phantom-like, or exhibit the phantom-divide crossing, while for a large range of the model parameters the universe results in a de Sitter, dark-energy-dominated, accelerating phase. Additionally, we can obtain earlytime inflationary solutions too, and thus provide a unified description of the cosmological history.PACS numbers: 04.50. Kd, 95.36.+x

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“…Aside from the possibility of large astrophysical [1,3,4] or cosmological [5][6][7][8][9] foreground and systematic contamination, possible solutions include extending the inflationary side or the ΛCDM side of this model. Inflationary modifications include a large running of the scalar tilt [1]; more explicit features in the inflationary scalar spectra [10][11][12]; or anticorrelated isocurvature perturbations [13].…”

Section: +007mentioning

confidence: 99%

Neutrinos help reconcile Planck measurements with both the early and local Universe

et al. 2014

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In light of the recent BICEP2 B-mode polarization detection, which implies a large inflationary tensor-to-scalar ratio r0.05 = 0.2 +0.07−0.05 , we re-examine the evidence for an extra sterile massive neutrino, originally invoked to account for the tension between the cosmic microwave background (CMB) temperature power spectrum and local measurements of the expansion rate H0 and cosmological structure. With only the standard active neutrinos and power-law scalar spectra, this detection is in tension with the upper limit of r < 0.11 (95% confidence) from the lack of a corresponding low multipole excess in the temperature anisotropy from gravitational waves. An extra sterile species with the same energy density as is needed to reconcile the CMB data with H0 measurements can also alleviate this new tension. By combining data from the Planck and ACT/SPT temperature spectra, WMAP9 polarization, H0, baryon acoustic oscillation and local cluster abundance measurements with BICEP2 data, we find the joint evidence for a sterile massive neutrino increases to ∆N eff = 0.98 ± 0.26 for the effective number and ms = 0.52 ± 0.13 eV for the effective mass or 3.8σ and 4σ evidence respectively. We caution the reader that these results correspond to a joint statistical evidence and, in addition, astrophysical systematic errors in the clusters and H0 measurements, and small-scale CMB data could weaken our conclusions.The recent detection of degree scale B-mode polarization in the Cosmic Microwave Background (CMB) by the BICEP2 experiment [1] implies that the inflationary ratio of tensor-to-scalar fluctuations is r 0.05 = 0.2 +0.07 −0.05 , a number in significant tension with the upper limit of r < 0.11 at 95% confidence level from the temperature anisotropy spectrum in the simplest inflationary ΛCDM cosmology [2]. This conflict occurs because the large angle temperature excess implied by the gravitational waves is not observed, and the mismatch cannot be compensated by parameter changes in this highly restricted, seven parameter model.Aside from the possibility of large astrophysical [1, 3, 4] or cosmological [5-9] foreground and systematic contamination, possible solutions include extending the inflationary side or the ΛCDM side of this model. Inflationary modifications include a large running of the scalar tilt [1]; more explicit features in the inflationary scalar spectra [10-12]; or anticorrelated isocurvature perturbations [13]. In the present work, we instead consider extensions to the matter content of the ΛCDM model that can alleviate this early Universe tension.In the ΛCDM cosmology, recall that the Planck CMB temperature anisotropy spectrum is also in conflict with * cdvorkin@ias.edu measurements of the local Universe [14][15][16]. The ΛCDM values for the current expansion rate -or Hubble constant, H 0 -and the abundance of galaxy clusters are individually in 2 − 3σ tension with direct measurements. While similar tensions existed in previous CMB data sets (e.g. [17]), the Planck results suggest a shift in the sound horizon...

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Can Primordial Magnetic Fields be the Origin of the BICEP2 Data?

Cited by 55 publications

References 42 publications

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Nonminimal torsion-matter coupling extension off(T)gravity

Neutrinos help reconcile Planck measurements with both the early and local Universe

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