Neutrino and Dark Radiation properties in
light of recent CMB observations
MA, Elena Giusarma, Olga Mena and Alessandro Melchiorri, arXiv:1303.0134 (2013)
ITP Cosmology Seminars, Heidelberg, 8 May 2013
Maria Archidiacono
MA, Erminia Calabrese and Alessandro Melchiorri, PRD 84 (2011) 1230008 Smith, MA, Cooray, De Bernardis, Melchiorri, Smith, PRD 85 (2012) 123521
Outline
• Cosmic Neutrino Background
• Massive Neutrinos and Dark Radiation effects on CMB and mpk
• State of art of the cosmological constraints on neutrino physics
• Adding external data sets and extending the cosmological scenarios
• Discrepancies and degeneracies
• Planck results
• Conclusions
Before Planck!
Weak interactions in the primordial plasma:
where
When we have the neutrino decoupling
If the decoupling was istantaneous, we get:
So nowaday
Cosmological standard value
(non-istantaneous decoupling)
enep cn
H
MeVTk decB 1
3/14/11/ TT
KT 95.1
Cosmic Neutrino Background
2me
ee
ee
t
T
t
046.3effN
effrad N
3/4
11
4
8
71
Cosmological constraints
seff NN 3
eV
mh
93
2
Probing the Neutrino mass with cosmological data
Early ISW
eV
mNh
93
2
Equivalence
f
cdm a 5
31
WMAP-9
Assuming 3 degenerate neutrinos Hinshaw et al (2013)
.).%95(3.1 lceVm
WMAP-7+SDSS+H0
Hannestad et al (2010)
Free-streaming:
.).%95(44.0 lceVm
H
vthFS
3
22
skmm
eVzvth /
11150
Model dependence: Curvature
m <0.45 eV (95%cl) <0.95 eV (95%cl)
k 10^3 0 7.52±7.74
The degeneracy considerably increases the uncertainty in the sum of neutrino masses.
WMAP-7 + ACT + SPT + BAO + H0
Smith, MA et al., PRD (2012)
Pre-Planck state of art for Neutrino mass
eVm )11.032.0(
SPT+WMAP7+H0+BAO+SPTcl: Hou et al. 2012
.).%95(39.0 lceVm
ACT+WMAP7+H0+BAO:
Sievers et al. 2013
The effective number of relativistic degrees of freedom
The total amount of relativistic degrees of freedom in the Universe is therefore parametrized in the following way:
2
3/4
2
11
4
8
71 hNh effR
A value of Neff > 3.046 is equivalent to the presence of a new «dark radiation» component :
4443
2
0 aaaaH
H DRM
Changing the Neutrino effective number essentially changes the expansion rate H at recombination. So it changes the size of the sound horizon at recombination:
and the damping at recombination:
Moreover a larger neutrino number increases the early ISW as the neutrino mass .
**
0 20/
as
t
ssH
da
a
cadtcr
Hou et al (2011)
Probing the Neutrino number with CMB data
*
0 2
2
3
22
)1(6
)1(15
6
)2(a
eT
dR
RR
Hna
dar
fixedd
Cosmological parameters degeneracies
Clusters and Ly-alpha surveys move to Neff = 3
Extra Dark Radiation 12.8 Gyrs
MA, Calabrese, Melchiorri, PRD (2011)
Pre-Planck state of art for Dark Radiation
WMAP-7+SPT
WMAP-7+SPT+BAO+H0 Hou et al. (2013)
48.062.3 effN
55.078.2 effNWMAP-7+ACT
WMAP-7+ACT+BAO+H0 Sievers et al. (2013)
35.071.3 effN
39.051.3 effN
Pre-Planck state of art for Dark Radiation
WMAP-9+SPT+ACT
Calabrese et al. (2013)
42.037.3 effN
W9+SPT W9+SPT +HST
W9+SPT +BAO
W9+SPT +BAO +HST
W9+SPT +SNLS
W9+SPT +SNLS +BAO
m (eV) 1.14±0.41 <0.50 0.46±0.18 0.33±0.17 <0.80 0.40±0.18
W9+ACT W9+ACT +HST
W9+ACT +BAO
W9+ACT +BAO +HST
W9+ACT +SNLS
W9+ACT +SNLS +BAO
m (eV) <0.89 <0.34 <0.53 <0.44 <0.49 <0.54
•CMB •CMB+HST •CMB+BAO •CMB+BAO+HST •CMB+SNLS •CMB+SNLS+BAO
MA, Giusarma, Melchiorri, Mena (2013)
CDM + 3 massive neutrinos
SPT ACT
CDM + 3 massive neutrinos + w
Sullivan et al. (2011)
SPT ACT
CDM + Neff W9+SPT W9+SPT
+HST W9+SPT +BAO
W9+SPT +BAO +HST
W9+SPT +SNLS
W9+SPT +SNLS +BAO
Neff 3.93±0.68 3.59±0.39 3.50±0.59 3.83±0.41 4.93±0.69 3.55±0.63
W9+ACT W9+ACT +HST
W9+ACT +BAO
W9+ACT +BAO +HST
W9+ACT +SNLS
W9+ACT +SNLS +BAO
Neff 2.74±0.47 3.12±0.38 2.77±0.49 3.43±0.36 2.77±0.49 2.83±0.47
SPT ACT
CDM + massive Neff W9+SPT W9+SPT
+HST W9+SPT +BAO
W9+SPT +BAO +HST
W9+SPT +SNLS
W9+SPT +SNLS +BAO
m (eV) 1.35±0.55 0.48±0.33 0.56±0.22 0.56±0.23 <0.91 0.50±0.21
Neff 3.66±0.61 4.08±0.54 3.76±0.67 4.21±0.46 4.04±0.68 3.87±0.68
W9+ACT W9+ACT +HST
W9+ACT +BAO
W9+ACT +BAO +HST
W9+ACT +SNLS
W9+ACT +SNLS +BAO
m (eV) <0.89 <0.34 <0.53 <0.44 <0.49 <0.54
Neff 2.64±0.51 3.20±0.38 2.63±0.48 3.44±0.37 2.75±0.44 2.78±0.46
SPT ACT
What Dark Radiation is made of? Sterile Neutrinos?
Exotic models:
• gravitational waves
• axions • decay of non-relativistic matter • Early Dark Energy
Massless neutrinos equations of perturbations:
.3,112
,5
3
15
8
5
23
,3
23
,3
2331
1,1,,
3,
2
2
2
lFllFFk
l
kFqc
kqa
a
k
q
a
akcq
hk
qkk
q
a
ac
a
a
lll
vis
eff
eff
The effective sound speed
The viscosity parameter 2
2
vis
eff
c
c
Effective sound speed and viscosity speed
3/122 viseff cc
0,3/1 22 viseff cc
1,3/1 22 viseff cc
3/122 viseff cc
If Dark Radiation is made of free-streaming
particles,
WMAP-7 ACT
3/1,2.0 22 viseff cc
3/1,7.0 22 viseff cc
Hu (1998), Smith et al. (2012)
CDM + DNeff + c2eff + c2
vis + 3 massive (0.3 eV) neutrinos with standard perturbations’ parameters
60.031.1 D effNW9+SPT
W9+SPT+HST
W9+ACT
W9+ACT+HST
32.038.0 D effN
39.092.0 D effN
41.062.0 D effN
W9+SPT+BAO+HST
W9+ACT+BAO+HST
07.015.02 visc
13.025.02 visc
W9+SPT/ACT+BAO+HST W9+SPT/ACT+BAO+HST
CDM + m + DNeff + c2eff + c2
vis
W9+SPT+BAO+HST
W9+ACT+BAO+HST
07.013.02 visc
11.025.02 visc
W9+SPT+BAO+HST
W9+ACT+BAO+HST
50.035.1 D effN
40.074.0 D effN
The evidence for neutrino mass still remains if SPT is combined with BAO
SPT ACT
To sum up …
W9+SPT W9+SPT+ external data
W9+ACT W9+ACT+external data
Standard Model Neutrino Mass
Detection Detection (BAO, BAO+HST, BAO+SN)
No detection
No detection
Extended Model Neutrino Mass
No detection
No detectionw:detect. with SN
No detection
No detection
Standard Model Dark Radiation
Evidence Evidence No evidence
Evidence only with BAO+HST
Extended Model Dark Radiation
Evidence Non-standard c2
vis
Evidence Non-standard c2
vis
No evidence
Evidence only with BAO+HST
Planck
.).%68(//)2.13.67(0 lcMpcskmH
ESA and the Planck Collaboration
“A simple but challenging Universe”
MpcskmH //4.28.730 HST, Riess et al (2011)
Planck and Neutrino mass
CDM + m
.).%95(66.0 lceVm
CDM + m + Alens
.).%95(08.1 lceVm
Planck+WMAP9polarization +highl(SPT+ACT)
ESA and the Planck Collaboration
Planck and Dark Radiation
.).%95(36.3 68.0
64.0 lcNeff
Planck+WMAP9polarization +highl(SPT+ACT)
Planck+WMAP9polarization +highl(SPT+ACT)+HST
.).%95(62.3 50.0
48.0 lcNeff
ESA and the Planck Collaboration
Planck and Sterile Neutrinos
Planck+WMAP9polarization +highl(SPT+ACT)
Planck+WMAP9polarization +highl(SPT+ACT) + BAO
.).%95(60.0 lceVm
.).%95(29.3 67.0
64.0 lcNeff
.).%95(32.3 54.0
52.0 lcNeff
.).%95(28.0 lceVm
ESA and the Planck Collaboration
Conclusions
• Detection of a non zero neutrino mass by SPT, tight upper bound on the absolute neutrino mass scale with Planck combined with high-l; • Evidence for extra dark radiation with SPT, standard Neff with ACT, evidence for extra dark radiation with Planck only if combined with HST. • The extra dark radiation seen by SPT can be related to exotic models (cvis
2 < 0.33 @95%cl) • Massive sterile neutrinos of Short BaseLine Oscillation experiments are not excluded, but a partial thermalisation must be invoked.
