1

Neutrino properties from cosmological measurements

Cosmorenata June’13

Olga MenaIFIC-CSIC/UV

• Introduction

• Neutrino masses: Cosmological signatures, current bounds & future perspectives

• Relativistic degrees of freedom Neff: Cosmological signatures, current bounds & future perspectives

According to standard cosmology, there are three active Dirac or Majorana neutrinos, which decouple from the thermal bath at a temperature O(1 MeV):

They do not inherit any of the energy associated to e+ e- annihilations, being colder than photons:

If these neutrinos are massive, their energy density, at T<<m is

and their thermal motion

According to neutrino oscillation physics, we know that there are at lest two Dirac or Majorana massive neutrinos:

4 Cosmorenata June’13

(Mena,Parke, PRD’04)

(Schwetz, Tortola &Valle, NJP’11)

According to neutrino oscillation physics, we know that there are at lest two Dirac or Majorana massive neutrinos:

(Schwetz, Tortola &Valle, NJP’01)

which translates into a lower bound on the total neutrino mass, depending on the hierarchy:

Planck collaboration has already added massive neutrinos in the vanilla-six parameter model, with Σmν,fiducial = 0.06 eV!

What ingredient, in your opinion, should be mandatory to change in the ΛCDM?

April’13 Cosmic Pies

ΛCDM + Σmν,fiducial = 0.06 eV ΛCDM + Σmν,fiducial < 0.23 eV

@ CMB: Early Integrated Sachs Wolfe effect. The transition from the relativistic to the non relativistic neutrino regime gets imprinted in the decays of the gravitational potentials near the recombination period. Maximal around the first peak.@LSS: Suppress structure formation on scales larger than the free streaming scale when they turn non relativistic. (Bond et al PRL’80)

QuickTime™ and aGIF decompressor

are needed to see this picture.

(M. Tegmark)

Sub-eV massive neutrinos cosmological signatures...

CMB needs HST or SNIa data due to the strong degeneracy between mν and H𝞶 o.

Pre-Planck state of the art of neutrino mass bounds

(Giusarma et al, PRD’12)

WMAP7+SPT09

WMAP7+SPT09 + SNLS

WMAP7+SPT09 + HST

CMB needs HST or SNIa data due to the strong degeneracy between mν and H𝞶 o. Galaxy clustering data helps enormously as well, either BAO (geometrical) or matter power spectrum (shape) info.

Pre-Planck state of the art of neutrino mass bounds

WMAP7+LRG DR7 (3D) + HST(Giusarma et al, PRD’12)

(de Putter et al, APJ’12)

WMAP7+LRG DR8 (2D) + HST

WMAP7+LRG DR9 (3D) + BAO + SNLS3 (Zhao et al, 1211.3741)

WMAP9+BAO+HST (Hinshaw et al, 1211.3741)

Pre-Planck state of the art of neutrino mass boundsRecent (Dec’12-Jan’13) high-l data from SPT’12 and ACT’13......

Pre-Planck state of the art of neutrino mass boundsRecent (Dec’12-Jan’13) high-l data from SPT and ACT find a different answer....

(J. Sievers et al, 1301.0824)

(Z. Hou et al, 1212.6267)

Pre-Planck state of the art of neutrino mass boundsRecent (Dec’12-Jan’13) high-l data from SPT and ACT find a different answer....

(J. Sievers et al, 1301.0824)

(Z. Hou et al, 1212.6267) QuickTime™ and aGIF decompressor

are needed to see this picture.

Post-Planck state of the art of neutrino mass 95%CL bounds

Planck+WP

+high-l

Planck+WP+BAO+ high-l

Planck+WP+HST + high-l

(Ade et al, 1303.5076)No cosmological evidence for neutrino masses. High-l’s not crucial if constraining only

mν.

Euclide-type survey 95%CL neutrino mass bounds

CMB Planck+shear+galaxies+Clusters

CMB Planck+shear+galaxies

CMB Planck+BAO+Clusters(Carbone et al, JCAP’12)

(Hamann et al, JCAP’12)

(Basse et al, 1304.2321)

1.5-5σ Detection of the minimum neutrino mass. 2.0-5σ Neutrino hierarchy extraction if weak lensing shear is also considered.

Σmν,fiducial = 0.056 eV

Future 95%CL neutrino mass bounds (Abazajian et al, Astropart.Phys.’11)

Neutrino abundances:

Neff = 3.046 standard scenario (after considering non instantaneous neutrino decoupling,flavor oscillations and QED finite temperature corrections).

Neff < 3.046 (less neutrinos): Non-standard neutrino couplings, neutrino decays, extremely low reheating temperature models.

Neff > 3.046 (more “neutrinos”): Sterile neutrino species (by SBL oscillation data).

Also KSVZ axions, extended dark sectors with light species (ADM).

(Kopp et al, 1303.3011)

(A. Melchiorri et al, JCAP’09)

Neff dark radiation species cosmological signatures...

@ CMB damping tail (SPT, ACT, Planck): Higher Neff higher H(z), modifying the photon diffusion scale at recombination

increasing the damping at high multipoles.

@CMB (WMAP, Planck): neutrino perturbations (anisotropic stress, 3rd peak)

The only degeneracy that still remains is the Neff-Yp (via ne), but Planck data helps in solving it.

(Hou et al, 1104.2333)

QuickTime™ and aGIF decompressor

are needed to see this picture.

Pre-Planck state of the art of Neff bounds

High-l data from SPT and ACT find (again and again!) a different answer...

(Z. Hou et al, 1212.6267)

(E. Calabrese et al, 1302.1841)

(J. Sievers et al, 1301.0824)

(Calabrese et al, 1302.1841; Archidiacono et al, 1303.0143; Di Valentino et al, 1301.7343)

QuickTime™ and aGIF decompressor

are needed to see this picture.

Post-Planck state of the art of Neff

(Ade et al, 1303.5076)

Interestingly, Neff >3.046 alleviates the 2.5σtension between the Planck and HST H0’s:

Yp degenerate with Neff (CMB damping tail). If both free parameters, Planck+WP+ highL:

95%CL

These new limits translate into constraints in sterile neutrino, axion and extended dark sector scenarios (Di Bari et al, Mirizzi et al, Di Valentino et al, Brust et al, Boehm et al)

Current and future Euclid-type 95% CL Neff regions

CMB Planck+shear+galaxies+Clusters (Neff,fid =3.046)} (Basse et al,

1304.2321)

3+0.046 due to non instantaneous decoupling, QED and flavor mixing

}

Planck+WP+highL

Planck+WP+highL+Yp

The small deviation of 0.046 from 3 can be proved with 2σ precision!

(Ade et al, 1303.5076)

BBN and NeffBBN theory predicts the abundances of D, 3He, 4He and 7Li which are fixed by t≃180 s. They are observed at late times low metallicity sites with little evolution are “ideal”.

High z QSO absorption lines.Destroyed in stars.

(F. Iocco et al, Phys. Rept’09)

Low metallicity extragalactic HII regions.Produced in stars.

(E. Aver et al, JCAP’12)

(P. A. R. Ade et al, 1303.5076)

Metal poor stars in our galaxy.Destroyed in stars and produced by galactic cosmic ray interactions.

Solar system and high metallicity HII galactic regions. 3He not used for cosmological constraints.

BBN and Neff

Neff changes the freeze out temperature of weak interactions:

Higher expansion rate, higher freeze out temperature, higher 4He fraction:

(G. Steigman’12)

(P. A. R. Ade et al, 1303.5076)

BBN and Neff(G. Steigman’12)

Hamann et at, JCAP’11

ΔNeff=2strongly disfavoured

+ξ O(0.1)

Neutrino perturbation/clustering parameters

Neutrino perturbation/clustering parameters

reduces pressure perturbations

reduces the amount of damping

pressure less fluid behaving as clustering dark matter

Neutrinoless double beta decay In some cases in which the ordinary beta decay processes are forbidden

energetically, the double beta decay processes might be allowed:

Two neutrons are converted into two protons, or viceversaThe decay rates are really slow, T~10^19 years, is a second order process in weak interactions.Two neutrino double beta decay processes have beenobserved experimentally for a number of isotopes.

If the lepton number is NOT conserved, the electron neutrino emitted in one of the elementary beta decay processes can be absorbed in another, leading to neutrinolessdouble beta decay. The decay rates are really small, T~10^23-25 years

Such a process would have a clear experimental signature: the sumof the energies of the 2 electrons or positrons should be equal to the total energy release, should be represented by a discrete energy line

This decay is only possible if neutrinos have Majorana masses, it violates the lepton number by two units! (assuming no other extensions of the SM)

Two neutrino double beta decay

Neutrinoless double beta decay

The 2 electrons or positrons’ energy should be equal to the total energy release, should be represented by a discrete energy line at the end point spectrum

Two neutrino double beta decay: Continuous spectrum

Neutrinoless double beta decay

The exchanged neutrino in the figure is emitted in a statewhich is almost totally of right handed helicity, but which contains a small piece, of order m/E, having left handedhelicity. When the exchanged neutrino is absorbed, theabsorbing left handed current can only absorb its left-handed component without further suppression.

Since the left-handed helicity component is O(m/E), the contribution of the neutrino exchange to the neutrinoless double beta decay amplitude is proportional to m. Summing over all the contributions: “effective Majorana neutrino mass”:

Sensitive, in principle, to Majorana neutrino phases!

In three families we have more Majorana phases: How many? two!Cancellations are really important!

Normal hierarchy

Inverted hierarchy

Degenerate spectrum

Strumia & Vissani,

2005

current 90%CL limits Kamland-ZEN+EXOfuture 90%CL sensitivities

SZ effect: Inverse Compton scattering of CMB phtons off hight energy electrons locatedin hot gas in galaxy clusters, and depends on both the thermal energy contained in the ICMas well as on the peculiar velocity of the cluster with respect to the CMB rest frame.