Neutrino properties from cosmological
measurements
Olga Mena
IFIC-CSIC/UV
1
Cosmorena
• Introduction
• Neutrino masses:
Cosmological signatures,
current bounds & future perspectives
• Relativistic degrees of freedom N
eff:
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:
(Schwetz, Tortola &Valle, NJP’11)
(Mena,Parke, PRD’04)
4
Cosmorena
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:
What ingredient, in your opinion, should be mandatory to change in the ΛCDM?
Planck collaboration has already added massive neutrinos in the vanilla-six parameter model,
with Σmν,fiducial = 0.06 eV!
April’13 Cosmic Pies
ΛCDM + Σmν,fiducial = 0.06 eV
ΛCDM + Σmν,fiducial < 0.23 eV
Sub-eV massive neutrinos cosmological signatures...
@ 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 a
GIF decompressor
are needed to see this picture.
(M. Tegmark)
Pre-Planck state of the art of neutrino mass bounds
CMB needs HST or SNIa data due to the strong degeneracy between mν 𝞶and Ho.
WMAP7+SPT09 + HST
WMAP7+SPT09 + SNLS
WMAP7+SPT09
(Giusarma et al,
PRD’12)
Pre-Planck state of the art of neutrino mass bounds
CMB needs HST or SNIa data due to the strong degeneracy between mν 𝞶and Ho.
Galaxy clustering data helps enormously as well, either BAO (geometrical) or matter power
spectrum (shape) info.
(Giusarma et al,
PRD’12)
WMAP7+LRG DR7 (3D) + HST
WMAP7+LRG DR8 (2D) + HST
WMAP7+LRG DR9 (3D) + BAO
WMAP9+BAO+HST
(de Putter et al,
APJ’12)
(Zhao et al,
1211.3741)
+ SNLS3
(Hinshaw et al,
1211.3741)
Pre-Planck state of the art of neutrino mass bounds
Recent (Dec’12-Jan’13) high-l data from SPT’12 and ACT’13......
Pre-Planck state of the art of neutrino mass bounds
Recent (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 bounds
Recent (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 a
GIF decompressor
are needed to see this picture.
Post-Planck state of the
(Adeart
et al, of neutrino mass 95%CL bounds
1303.5076)
No cosmological evidence for neutrino masses. High-l’s not crucial if constraining only mν.
Planck+WP
+high-l
Planck+WP+BAO
Planck+WP+HST
+ high-l
+ high-l
Euclide-type survey 95%CL neutrino mass bounds
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
CMB
(Basse et al,
Planck+shear+galaxies+Clusters1304.2321)
CMB
(Hamann et al,
Planck+shear+galaxiesJCAP’12)
CMB Planck+BAO+Clusters
(Carbone et al,
JCAP’12)
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).
(Kopp et al,
1303.3011)
(A. Melchiorri et al,
JCAP’09)
Also KSVZ axions, extended dark sectors with light species (ADM).
Neff dark radiation species cosmological signatures...
@CMB (WMAP, Planck):
QuickTime™ and a
neutrino perturbations
GIF decompressor
are needed to see this picture.
(anisotropic stress, 3rd peak)
(Hou et al, 1104.2333)
@ CMB damping tail (SPT, ACT, Planck):
Higher Neff higher H(z), modifying the photon
diffusion scale at recombination
increasing the damping at high multipoles.
The only degeneracy that still remains is the
Neff-Yp (via ne), but Planck data helps in solving it.
Pre-Planck state of the art of Neff bounds
High-l data from SPT and ACT find (again and again!) a different answer...
(Calabrese et al, 1302.1841; Archidiacono et al, 1303.0143; Di Valentino et al, 1301.7343)
(J. Sievers et al, 1301.0824)
(E. Calabrese et al, 1302.1841)
(Z. Hou et al, 1212.6267)
QuickTime™ and a
GIF decompressor
are needed to see this picture.
Post-Planck state of the art of Neff
(Ade et al,
1303.5076)
95%CL
Interestingly, Neff >3.046 alleviates the 2.5σtension between the Planck and HST H0’s:
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)
Yp degenerate with Neff (CMB damping tail). If both free parameters, Planck+WP+ highL:
Current and future Euclid-type 95% CL Neff regions
(Ade et al,
Planck+WP+highL+Yp 1303.5076)
Planck+WP+highL
}
}
3+0.046 due to
non instantaneous
decoupling, QED
and flavor mixing
CMB Planck+shear+galaxies+Clusters (Neff,fid =3.046)
(Basse et al,
1304.2321)
The small deviation of 0.046 from 3 can be proved
with 2σ precision!
BBN and Neff
BBN 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”.
Low metallicity extragalactic HII regions.
Produced in stars.
(E. Aver et al,
JCAP’12)
(P. A. R. Ade et al,
1303.5076)
High z QSO absorption lines.
Destroyed in stars.
(F. Iocco et al, Phys.
Rept’09)
Solar system and high metallicity HII galactic
regions. 3He not used for cosmological constraints.
Metal poor stars in our galaxy.
Destroyed in stars and produced by
galactic cosmic ray interactions.
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 (G.
and Neff
Steigman’12)
Hamann et at,
JCAP’11
ΔNeff=2
strongly 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 viceversa
The decay rates are really slow, T~10^19 years, is a second
order process in weak interactions.
Two neutrino double beta decay processes have been
observed 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 neutrinoless
double beta decay. The decay rates are really small, T~10^23-25 years
Such a process would have a clear experimental signature: the sum
of 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: Continuous spectrum
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
Neutrinoless double beta decay
The exchanged neutrino in the figure is emitted in a state
which is almost totally of right handed helicity, but which
contains a small piece, of order m/E, having left handed
helicity. When the exchanged neutrino is absorbed, the
absorbing left handed current can only absorb its lefthanded 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
current 90%CL limits Kamland-ZEN+EXO
future 90%CL sensitivities
Strumia & Vissani,
2005
SZ effect: Inverse Compton scattering of CMB phtons off hight energy electrons located
in hot gas in galaxy clusters, and depends on both the thermal energy contained in the ICM
as well as on the peculiar velocity of the cluster with respect to the CMB rest frame.