Relic Neutrinos, thermal axions and cosmology in

early 2014 Elena GiusarmaarXiv:1403.4852Based on work in collaboration with:

E. Di Valentino, M. Lattanzi, A. Melchiorri, O. Mena

Outline Cosmological neutrino mass implications

Existence of extra hot relic components as dark radiation relics, steriles neutrino species and/or thermal axions

Cosmological data used in our numerical analysis

Neutrino mass bounds in different cosmological scenarios

Impact of BICEP2 measurements for the relativisitc degrees of freedom and neutrino masses

Conclusions

In the stanard cosmology hot, thermal relics are identified with the three light, active neutrino flavours of the Standard Model of elementary particles. Neutrino masses have an impact in the different cosmological observable:

• CMB: a) Early Integrated Sachs Wolfe effect. The transition from the relativistic to the non relativistic neutrino regime affect the decays of the gravitational potentials at decoupling period (especially near the first acoustic peak). b) Suppression of lensing potential (with Planck).

• LSS: Suppression of structure formation on scales smaller than the free streaming scale when neutrinos turn non relativistic.

Planck+WMAP 9-polarization data:

Planck+WMAP 9-polarization +HST data:

(M. Tegmark)

Planck+WMAP 9-polarization +HST+BAO data:

(Ade et al ‘13 Planck Collaboration )

∑mν <1.11 eV at 95% CL

∑mν <0.21 eV at 95% CL

∑mν <0.26 eV at 95% CL

Massless sterile neutrino species: e.g. extra degrees of freedom produced by the annihilation of asymmetric Dark Matter

Extra steriles massive neutrino species: motivated by the so-called neutrino oscillation anomalies

Thermal axion: motivated by the strong CP problem

Candidates for extra hot relic components

These extra species

Have an associated free streaming scales, reducing the growth of matter fluctuations at small scales

Contribute to the effective number of relativistic degrees of freedom Neff

Neff= 3.046+ΔNeff

Data1 CMB:

o Planck temperature anisotropies, including lensing potential

o WMAP 9-year polarizationo ACT and SPT measurements at small scaleso B-mode polarization measurements from BICEP2

Large scale structure:o SDSS Data Release 7o 6-degree Field Galaxy Survey o New BOSS Data Release 11o WiggleZ survey (the full shape of the matter

power spectrum and the geometrical BAO information )

Baryon Acoustic Oscillation (BAO) data

Data2

σ8 measurements:o CFHTLens surveyo Planck Sunyaev-Zeldovich cluster catalog

Big Bang Nucleosynthesis light elements abundance:

Hubble constant measurements:o Hubble Space Telescope

Cosmological parameters1. ΛCDM model with 3 massive neutrino species:

Extra Radiation Component at the BBN period

2. ΛCDM model with 3 massive neutrino species and thermal axion:

3. ΛCDM model with 3 massive neutrino and ΔNeff massless dark radiation species:

4. ΛCDM model with 3 active massive neutrinos plus ΔNeff massive steriles neutrino species:

Cosmological parameters

Ts , Tν current temperature of the sterile and active neutrino species. ms real mass of sterile neutrino species. UNIFORM PRIORS for the cosmological parameters:

Neff priors refer to the massless (massive) case

ΔNeff=Neff-3.46=(Ts /Tν )4

Main Results(1)68% and 95% CL allowed regions in the (∑mν, H0) and in the (∑mν, σ8 ) plane

The allowed neutrino mass regions are displaced after considering Planck cluster data and a non zero value on ∑mν is favoured.

1. ΛCDM model with 3 massive neutrino species:

CMB+DR11+BAO+HST:CMB+DR11+BAO+HST+SZ Cluster:CMB+DR11+BAO+HST+CFHTLens:

The addition of the constraints on σ8 and Ωm from the CFHTLens survey displaces the bounds on the neutrino mass to higher values.

Giusarma et al arXiv:1403.4852

Main Results(2) 68% and 95% CL allowed regions in the (∑mν, ma) plane for different combinations of data

Only with Planck SZ cluster data a non zero value of axion mass is favoured at the 2.2σNo evidence for non-zero neutrino masses nor for non-zero axion mass.

2. ΛCDM model with 3 massive neutrino species and thermal axion:

CMB+DR11+WZ+HST+SZ Cluster:CMB+DR11+BAO+HST+SZ Cluster:

Evidence for neutrino mass of 0.2 eV at 3σ on only for one case

Giusarma et al arXiv:1403.4852

Main Results(3) 68% and 95% CL allowed regions in the (∑mν, Neff) and in the (Neff, H0 ) plane

The prior on the value of the Hubble constant from HST increases the mean value on Neff

3. ΛCDM model with 3 massive neutrino and ΔNeff=Neff-3.46 massless dark radiation species:

CMB+DR11+WZ+HST+BBN (Cooke et al.): NO EVIDENCE FOR Neff >3

CMB+DR11+WZ+HST+BBN (Iocco et al.): EVIDENCE FOR Neff >3

Giusarma et al arXiv:1403.4852

Main Results(4) 4. ΛCDM model with 3 active massive neutrinos plus ΔNeff massive steriles neutrino species:

68% and 95% CL allowed regions in the (∑mν, Neff) and in the (∑mν, mseff) plane

The bound on Neff (∑mν ) is slightly larger (more stringent) than in massless sterile neutrino scenario due to the degeneracy with ms

eff NO SIGNIFICANT PREFERENCE FOR Neff>3 CMB+DR11+WZ+HST+BBN(Cooke

et al.): CMB+DR11+WZ+HST+BBN(Iocco et al.): SIGNIFICANT PREFERENCE FOR Neff >3

Giusarma et al arXiv:1403.4852

BICEP2 measurementsBICEP2: detection at about 5.9σ for B-mode polarization on large scales

at 68% CL

Ade et al ‘14 BICEP2 Collaboration

Apparent tension with Planck+WP limit: r<0.11 at 95% cl

What is the impact of BICEP2 measurements on neutrino properties?ΛCDM +r model with 1 massive neutrino (0.06 eV) and ΔNeff=Neff-3.046 massless dark radiation species:ΛCDM +r model with 3 massive neutrino:

Evidence for Neff>3 but no indication for neutrino masses

Extra relativistic component seems to solve the tension between the Planck and BICEP2 experiments on r

Giusarma et al arXiv:1403.4852r = 0.15±0.04 at 68% CL

Conclusions• Constraints on the masses of the different thermal relics in different scenarios using

the most recent comological data

• In the minimal three active massive neutrino scenario we found that CFHTLens survey displaces the bound on neutrino masses to higher value. Planck cluster data favours a non zero value on ∑mν of about 0.3 eV at 4σ.

• In the scenario with thermal axions and active massive neutrino species we found that only considering the Planck SZ cluster data plus CMB+DR11+ BAO+HST there exists a prefernce for axion mass of 0.6 eV at the obout 2.2σ and only combining Planck SZ cluster data with CMB+DR11+ WZ+HST there is an evidence for neutrino mass of 0.2 eV at about 3σ.

• In the scenario with massive neutrinos and ΔNeff dark radiation species the bounds on ∑mν are less stringent. BBN constraints reduce both mean value and the errors ok Neff significantly.

• Considering B-mode polarization measurements by BICEP2 experiment +Planck+WP data, we found that an extra realivistic component could solve the tension between the two experiments on the amplitude of tensor mode.