Title: Neutrino masses from cosmological observables
1Neutrino masses from cosmological observables
- Sergio Pastor (IFIC)
- Benasque Cosmology workshop
- 15 / 08 / 2006
2Outline
Introduction the Cosmic Neutrino Background
Relic Neutrinos as DM
Neutrino masses from cosmological observables
Effect of neutrino masses on cosmological
observables
Current bounds and future sensitivities
3This is a neutrino!
4Neutrinos coupled by weak interactions(in
equilibrium)
Free-streaming neutrinos (decoupled) Cosmic
Neutrino Background
Neutrinos keep the energy spectrum of a
relativistic fermion with eq form
Primordial Nucleosynthesis
TMeV tsec
5Relativistic neutrinos
At least 2 species are NR today
TeV
- Neutrino cosmology is interesting because Relic
neutrinos are very abundant - The CNB contributes to radiation at early times
and to matter at late times (info on the number
of neutrinos and their masses) - Cosmological observables can be used to test
non-standard neutrino properties
6Evolution of the background densities 1 MeV ? now
Oi ?i/?crit
7The Cosmic Neutrino Background
- Number density
- Energy density
Massless
Massive m?gtgtT
8We know that flavour neutrino oscillations exist
From present evidences of oscillations from
experiments measuring atmospheric, solar, reactor
and accelerator neutrinos
Evidence of Particle Physics beyond the Standard
Model !
9Mixing Parameters...
From present evidences of oscillations from
experiments measuring atmospheric, solar, reactor
and accelerator neutrinos
Mixing matrix U
Maltoni, Schwetz, Tórtola, Valle, NJP 6 (2004) 122
10Mixing Parameters...
From present evidences of oscillations from
experiments measuring atmospheric, solar, reactor
and accelerator neutrinos
Mixing matrix U
Maltoni, Schwetz, Tórtola, Valle, NJP 6 (2004) 122
11... and neutrino masses
Data on flavour oscillations do not fix the
absolute scale of neutrino masses
eV
NORMAL
INVERTED
atm
solar
What is the value of m0 ?
12Direct laboratory bounds on m?
Searching for non-zero neutrino mass in
laboratory experiments
- Tritium beta decay measurements of endpoint
energy - m(?e) lt 2.2 eV (95 CL) Mainz-Troitsk
- Future experiments (KATRIN) m(?e) 0.3 eV
- Neutrinoless double beta decay if Majorana
neutrinos - 76Ge experiments ImeeI lt 0.4hN eV
13Absolute mass scale searches
Tritium ? decay lt 2.2 eV
Neutrinoless double beta decay lt 0.4-1.6 eV
14Neutrinos as Dark Matter
- Neutrinos are natural DM candidates
- They stream freely until non-relativistic
(collisionless phase mixing)
Neutrinos are HOT Dark Matter - First structures to be formed when Universe
became matter -dominated - Ruled out by structure formation CDM
15Neutrinos as Dark Matter
- Neutrinos are natural DM candidates
- They stream freely until non-relativistic
(collisionless phase mixing)
Neutrinos are HOT Dark Matter - First structures to be formed when Universe
became matter -dominated - Ruled out by structure formation CDM
16Neutrinos as Hot Dark Matter
Massive Neutrinos can still be subdominant DM
limits on m? from Structure Formation (combined
with other cosmological data)
17Power Spectrum of density fluctuations
18Neutrinos as Hot Dark Matter effect on P(k)
Massive Neutrinos can still be subdominant DM
limits on m? from Structure Formation (combined
with other cosmological data)
- Effect of Massive Neutrinos suppression of
Power at small scales
f?
19Structure formation after equality
baryon and CDM experience gravitational clustering
20Structure formation after equality
baryon and CDM experience gravitational clustering
21Structure formation after equality
baryon and CDM experience gravitational clustering
22Structure formation after equality
baryon and CDM experience gravitational clustering
growth of dr/r (k,t) fixed by  gravity vs.
expansion balance ? dr/r ? a
23Structure formation after equality
baryon and CDM experience gravitational clustering
neutrinos experience free-streaming with v c
or ltpgt/m
24Structure formation after equality
baryon and CDM experience gravitational clustering
baryon and CDM experience gravitational clustering
neutrinos experience free-streaming with v c
or ltpgt/m
25Structure formation after equality
baryon and CDM experience gravitational clustering
baryon and CDM experience gravitational clustering
neutrinos experience free-streaming with v c
or ltpgt/m
- neutrinos cannot cluster below a diffusion
length - l ? v dt lt ? c dt
26Structure formation after equality
baryon and CDM experience gravitational clustering
baryon and CDM experience gravitational clustering
neutrinos experience free-streaming with v c
or ltpgt/m
- neutrinos cannot cluster below a diffusion
length - l ? v dt lt ? c dt
27Structure formation after equality
J.Lesgourgues SP, Phys Rep 429 (2006) 307
astro-ph/0603494
28Structure formation after equality
a
dcdm
db
1-3/5fn
a
Massive neutrinos f?0.1
dn
dg
metric
J.Lesgourgues SP, Phys Rep 429 (2006) 307
astro-ph/0603494
29Effect of massive neutrinos on P(k)
Observable signature of the total mass on P(k)
P(k) massive P(k) massless
various f?
Lesgourgues SP, Phys. Rep. 429 (2006)
307
30DATA on CMB temperature /polarization anisotropies
31Effect of massive neutrinos on the CMB spectra
- Direct effect of sub-eV massive neutrinos on the
evolution of the baryon-photon coupling is very
small - Impact on CMB spectra is indirect non-zero O?
today implies a change in the spatial curvature
or other Oi . The background evolution is
modified - Ex in a flat universe,
- keep O?OcdmObO?1
- constant
32Effect of massive neutrinos on the CMB spectra
Problem with parameter degeneracies change
in other cosmological parameters can mimic the
effect of nu masses
33Effect of massive neutrinos on the CMB and Matter
Power Spectra
Max Tegmark www.hep.upenn.edu/max/
34How to get a bound (measurement) of neutrino
masses from Cosmology
Fiducial cosmological model (Obh2 , Omh2 , h ,
ns , t, Sm? )
PARAMETER ESTIMATES
35Cosmological Data
- CMB Temperature WMAP plus data from other
experiments at large multipoles (CBI, ACBAR,
VSA) - CMB Polarization WMAP,
- Large Scale Structure
- Galaxy Clustering (2dF,SDSS)
- Bias (Galaxy, ) Amplitude of the Matter P(k)
(SDSS,s8) - Lyman-a forest independent measurement of
power on small scales - Baryon acoustic oscillations (SDSS)
- Bounds on parameters from other data SNIa (Om),
HST (h),
36Cosmological Parameters example
SDSS Coll, PRD 69 (2004) 103501
37Cosmological bounds on neutrino mass(es)
A unique cosmological bound on m? DOES NOT exist !
38Cosmological bounds on neutrino mass(es)
A unique cosmological bound on m? DOES NOT exist !
- Different analyses have found upper bounds on
neutrino masses, since they depend on - The combination of cosmological data used
- The assumed cosmological model number of
parameters (problem of parameter degeneracies) - The properties of relic neutrinos
39Cosmological bounds on neutrino masses using WMAP1
Bound on Sm? (eV) 95 CL Data used
Ichikawa et al, PRD 71 (2005) 043001 Sánchez et al, MNRAS 366 (2006) 189 MacTavish et al, astro-ph/0507503 1.6 - 3.1 CMB only
Hannestad, JCAP 0305 (2003) 004 SDSS Coll., PRD 69 (2004) 103501 Barger et al, PLB 595 (2004) 55 Crotty et al, PRD 69 (2004) 123007 Rebolo et al, MNRAS 353 (2004) 747 Fogli et al. PRD 70 (2004) 113003 Seljak et al, PRD 71 (2005) 103515 Sánchez et al, MNRAS 366 (2006) 189 MacTavish et al, astro-ph/0507503 1.0 - 1.7 0.6-1.2 WMAP1, other CMB, 2dF/SDSS-gal HST,SNIa
WMAP Coll., ApJ Suppl 148 (2003) 175 Fogli et al. PRD 70 (2004) 113003 Seljak et al, PRD 71 (2005) 103515 MacTavish et al, astro-ph/0507503 Hannestad, hep-ph/0409108 0.42-0.68 WMAP1, other CMB, 2dF/SDSS-gal, 2dF/SDSS-bias and/or Ly-a
40Cosmological bounds on neutrino masses using WMAP3
Bound on Sm? (eV) 95 CL Data used
WMAP Coll., astro-ph/0603449 Fukugita et al, astro-ph/0605362 Kristiansen et al, astro-ph/0608017 1.7 2.3 CMB only
WMAP Coll., astro-ph/0603449 Goobar et al, astro-ph/0602155 0.68 0.91 WMAP3, other CMB, 2dF/SDSS-gal, SNIa
Goobar et al, astro-ph/0602155 Seljak et al, astro-ph/0604335 Kristiansen et al, astro-ph/0608017 0.17-0.48 WMAP3, other CMB, 2dF/SDSS-gal, SDSS-BAO and/or Ly-a
Fogli et al., hep-ph/0608060
41Neutrino masses in 3-neutrino schemes
CMB galaxy clustering
Fig from Strumia Vissani, NPB726(2005)294
420?2? and Cosmology
Fogli et al., hep-ph/0608060
43Future sensitivities to Sm?
When future cosmological data will be available
- CMB (TP) galaxy redshift surveys
- CMB (TP) and CMB lensing
- Weak lensing surveys
- Weak lensing surveys CMB lensing
44PLANCKSDSS
- Fisher matrix analysis expected sensitivities
assuming a fiducial cosmological model, for
future experiments with known specifications
Fiducial cosmological model (Obh2 , Omh2 , h ,
ns , t, Sm? ) (0.0245 , 0.148 , 0.70 , 0.98 ,
0.12, Sm? )
45Future sensitivities to Sm? new ideas
weak gravitational and
CMB lensing lensing
No bias uncertainty Small scales much closer to
linear regime Tomography 3D reconstruction
Makes CMB sensitive to smaller neutrino masses
46Future sensitivities to Sm? new ideas
weak gravitational and
CMB lensing lensing
sensitivity of future weak lensing
survey (4000º)2 to m? s(m?) 0.1 eV Abazajian
Dodelson PRL 91 (2003) 041301
sensitivity of CMB (primary lensing) to
m? s(m?) 0.15 eV (Planck) s(m?) 0.044 eV
(CMBpol) Kaplinghat, Knox Song PRL 91 (2003)
241301 Lesgourgues, Perotto, SP Piat PRD 73
(2006) 045021
47CMB lensing recent analysis
s(M?) in eV for future CMB experiments alone
Lesgourgues et al, PRD 73 (2006) 045021
48CMB lensing recent analysis
Perotto et al, astro-ph/06062271
49Summary of future sensitivities
Lesgourgues SP, Phys. Rep. 429 (2006) 307
Future cosmic shear surveys
50For more details see
Physics Reports 429 (2006) 307-379
astro-ph/0603494
51Conclusions
Cosmological observables can be used to bound
(or measure) the absolute scale of neutrino
masses. Information complementary to laboratory
results
?
Current bounds on the sum of neutrino masses
from cosmological data (best Sm?lt0.2-0.4 eV,
conservative Sm?lt1 eV)
Sub-eV sensitivity in the next future (0.1-0.2
eV and better) Test degenerate mass region
and eventually the IH case