Cosmological parameters from combining the Lyman-α forest with CMB, galaxy clustering and SN constraints

Seljak, Uroš; Slosar, Anže; McDonald, Patrick

doi:10.1088/1475-7516/2006/10/014

Cited by 667 publications

(827 citation statements)

References 56 publications

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“…The dashed line at α = 1/3 shows the degeneracy condition (where ∆χ 2 is equal to zero by construction) and the vertical dashed line corresponds to the tightest limit on the sum of neutrino mass found in literature [9], that is 0.4eV. A few recent preprints find tighter limits using the latest cosmological data: 0.3eV in [37] and 0.17eV in [38]. Solid thin lines are contours of constant ∆χ 2 as stated in the caption.…”

Section: Resultsmentioning

confidence: 99%

Detecting neutrino mass difference with cosmology

Slosar

2006

Phys. Rev. D

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Cosmological parameter estimation exercises usually make the approximation that the three standard neutrinos have degenerate mass, which is at odds with recent terrestrial measurements of the difference in the square of neutrino masses. In this paper we examine whether the use of this approximation is justified for the cosmic microwave background (CMB) spectrum, matter power spectrum and the CMB lensing potential power spectrum. We find that, assuming δm 2 23 ∼ 2.5 × 10 −3 eV 2 in agreement with recent Earth based measurements of atmospheric neutrino oscillations, the correction due to non-degeneracy is of the order of precision of present numerical codes and undetectable for the foreseeable future for the CMB and matter power spectra. An ambitious experiment that could reconstruct the lensing potential power spectrum to the cosmic variance limit up to ℓ ∼ 1000 will have to take the effect into account in order to avoid biases. The degeneracies with other parameters, however, will make the detection of the neutrino mass difference impossible. We also show that relaxing the bound on the neutrino mass difference will also increase the error-bar on the sum of neutrino masses by a factor of up to a few. For exotic models with significantly non-degenerate neutrinos the corrections due to non-degeneracy could become important for all the cosmological probes discussed here.

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Section: Resultsmentioning

confidence: 99%

Detecting neutrino mass difference with cosmology

Slosar

2006

Phys. Rev. D

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“…Nevertheless this has been the standard procedure in most of the recent parameter analyses based on WMAP-3 [2,4]. The caveat is especially relevant because we found a degeneracy between m ν = 0 and N eff , based on the cosmological data available in 2003 [5][6][7][8].…”

Section: Introductionmentioning

confidence: 83%

Neutrino masses and cosmic radiation density: combined analysis

Hannestad

Raffelt

2006

J. Cosmol. Astropart. Phys.

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Abstract. We determine the range of neutrino masses and cosmic radiation content allowed by the most recent CMB and large-scale structure data. In contrast to other recent works, we vary these parameters simultaneously and provide likelihood contours in the two-dimensional parameter space of N eff , the usual effective number of neutrino species measuring the radiation density, and m ν . The allowed range of m ν and N eff has shrunk significantly compared to previous studies. The previous degeneracy between these parameters has disappeared, largely thanks to the baryon acoustic oscillation data. The likelihood contours differ significantly if m ν resides in a single species instead of the standard case of being equally distributed among all flavors. For m ν = 0 we find 2.7 < N eff < 4.6 at 95% CL while m ν < 0.62 eV at 95% CL for the standard radiation content.

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“…It has been claimed that a running of the spectral index will be excluded in the presence of SDSS Lyman α observations [31,32,33,34], the systematics of Lyman α data are relatively less constrained [1,23] and we leave this in a separate investigation to be reported in [35], and detailed analysis with other additional possible degeneracies in [36]. For many years neutrinos have played a fundamental role in both physics and astrophysics, and provided venues of new physics such as the parity violation and oscillations with tiny masses.…”

Section: Pacs Number(s): 9880cqmentioning

confidence: 99%

Weighing neutrinos in the presence of a running primordial spectral index

Feng

Xia

Yokoyama

et al. 2006

J. Cosmol. Astropart. Phys.

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The three-year WMAP(WMAP3), combined with other cosmological observations from galaxy clustering and Type Ia Supernova (SNIa), prefers a non-vanishing running of the primordial spectral index independent of the low CMB multipoles. Motivated by this feature we study cosmological constraint on the neutrino mass, which severely depends on what prior we adopt for the spectral shape of primordial fluctuations, taking possible running into account. As a result we find a more stringent constraint on the sum of the three neutrino masses, mν < 0.76eV (2 σ), compared with mν < 0.90eV (2 σ) for the case where power-law prior is adopted to the primordial spectral shape. PACS number(s): 98.80.CqThe three year Wilkinson Microwave Anisotropy Probe observations (WMAP3) [1,2,3,4, 5] have marked another milestone on the precision cosmology of the Cosmic Microwave Background (CMB) Radiation. The simplest six-parameter power-law ΛCDM cosmology is in remarkable agreement with WMAP3 together with the large scale structure(LSS) of galaxy clustering as measured by 2dF [6] and SDSS [7] and with the Type Ia Supernova (SNIa) as measured by the Riess "gold" sample [8] and the first year SNLS [9]. This agreement between the above "canonical" cosmological model and observations can be used to test a number of possible new physics, such as the equation of state of dark energy, neutrino masses, time variation of fundamental constants, etc.Among them, the constraint on the neutrino or hot dark matter mass can be obtained from the freestreaming modification of the transfer function of the matter power spectrum. We should note, however, that if one allowed any shape of primordial spectrum, the freestreaming effect could easily be compensated by some nontrivial shape of the primordial spectrum, so that one cannot obtain sensible limit on the neutrino mass. That is, we can obtain a nontrivial bound on neutrino mass if and only if we adopt some prior on the shape of primordial power spectrum such as a simple power-law. From the above argument, we expect that as we allow more degrees of freedom on the primordial spectrum beyond a power-law, the constraint on the neutrino mass would be less stringent in general.As for the shape of the primordial power spectrum, it is noteworthy that a significant deviation has been observed by WMAP3 from the simplest Harrison-Zel'dovich spectrum, and that this feature is more eminent with the combination of all the currently available CMB, LSS and SNIa (dubbed the case of "All" in [5]). Moreover, a nontrivial negative running of the scalar spectral index α s , whose existence was studied even before WMAP epoch [10,11], was favored by the first-year WMAP papers [12,13,14]. But its preference was somehow diminished as corrections to the likelihood functions were made [15].However, the new WMAP3 data prefers again a negative running in the "All" combination [5].If confirmed, a nonvanishing running of α s would not only constrain inflationary cosmology significantly [16,17,18,19,20,21], but also affect the cosmological c...

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Cosmological parameters from combining the Lyman-α forest with CMB, galaxy clustering and SN constraints

Cited by 667 publications

References 56 publications

Detecting neutrino mass difference with cosmology

Detecting neutrino mass difference with cosmology

Neutrino masses and cosmic radiation density: combined analysis

Weighing neutrinos in the presence of a running primordial spectral index

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