Cosmological mass Cosmological mass bounds bounds on hot-dark matter on hot-dark matter axions axions Alessandro MIRIZZI Alessandro MIRIZZI (MPI, Munich) (MPI, Munich) NOW 2008- Neutrino Oscillation Workshop NOW 2008- Neutrino Oscillation Workshop Conca Specchiulla, September 6-13 2008 Conca Specchiulla, September 6-13 2008 [based on works in collaboration with S.Hannestad, G.G. [based on works in collaboration with S.Hannestad, G.G. Raffelt, Y.Y.Y. Wong] Raffelt, Y.Y.Y. Wong]
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Cosmological mass bounds on hot-dark matter axions Alessandro MIRIZZI (MPI, Munich) NOW 2008- Neutrino Oscillation Workshop Conca Specchiulla, September.
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Cosmological mass Cosmological mass boundsbounds
on hot-dark matter on hot-dark matter axionsaxions
Alessandro MIRIZZIAlessandro MIRIZZI
(MPI, Munich)(MPI, Munich)
NOW 2008- Neutrino Oscillation WorkshopNOW 2008- Neutrino Oscillation Workshop
Conca Specchiulla, September 6-13 2008Conca Specchiulla, September 6-13 2008
[based on works in collaboration with S.Hannestad, G.G. Raffelt, Y.Y.Y. Wong][based on works in collaboration with S.Hannestad, G.G. Raffelt, Y.Y.Y. Wong]
If fa < 1.2 ×1012 GeV there would be a primordial population of axions produced in hot thermal plasma [Turner (1987), Masso’ (2002)]
Freeze-out temperature
If axions were sufficiently strong interacting (fa < 3 ×107 GeV, ma > 0.2 eV) they decouple after QCD phase transition (T < 200 MeV). The most generic interaction process involves hadrons rather than quarks and gluons that would be relevant at earlier epochs.
There would be a background of low-mass (~ eV) relic axions
Massive neutrinos affect Large Scale Structures.
They smooth out the distribution: no small scale structures.
Cold Dark Matter(no neutrino mass)
Hot + Cold Dark Matter(non-zero neutrino mass)
S. Dodelson, ‘04
Low mass thermal relics affect structure formation because they are source of hot dark matter
Alessandro Mirizzi NOW 2008 Conca Specchiulla, 6-13 September 2008
POWER SPECTRUM OF MATTER DENSITY FLUCTUATIONS
xx
Density contrast
2( ) kP k
Power spectrum
Alessandro Mirizzi NOW 2008 Conca Specchiulla, 6-13 September 2008
Neutrinos affect the Power Spectrum of the 2-point density correlation function.
Alessandro Mirizzi NOW 2008 Conca Specchiulla, 6-13 September 2008
Freeze-out temperatureCosmic thermal degrees offreedom at axion freeze-out
Present-day axion density*,
*,
( )
( ) 2S
aS
ng todayn
g decoupling
*, ( ) 3.91Sg today 3411 n cm
3112 n cm
AXION HOT-DARK MATTER
H
AXION HOT-DARK MATTER LIMIT FROM PRECISION DATA
Credible regions for neutrinos plus axions HDM (WMAP-5, LSS, BAO; SN-Ia)
Hannestad, Mirizzi, Raffelt & Wong [arXiV: 0803.1585]
Dashed (red) curves: Same with WMAP-3
HMRW [arXiv: 0706.4198]
Marginalizing over unknown neutrino hot-dark matter component
WMAP5, LSS, BAO, SN Ia
Hannestad, Mirizzi, Raffelt & Wong [arXiV:0803.1585]
WMAP3, small-scale CMB, HST, BBN, LSS, Ly
Melchiorri, Mena & Slosar [arXiV: 0705.2695]
1 eV (95% CL)am
0.4 eV (95% CL)am
NEW AXION MASS LIMIT
Our limit ma < 1 eV, corrisponding to fa> 5.7×106 GeV, is comparable with the one obtained with the globular-cluster. However, the globular cluster limit depends on axion-photon coupling that is rather model dependent.
Our limit closes the “hadronic axion window” left open by SN1987A arguments
New cosmological mass limit
Alessandro Mirizzi NOW 2008 Conca Specchiulla, 6-13 September 2008
IMPLICATION FOR AXION SEARCHES
Searches for solar axions: Axion helioscopes
Axion-photon oscillationPrimakoff process
• Tokyo axion helioscope Results since 1998
• CERN Axion Solar Telescope (CAST) Data since 2003
Sun Laboratory
CAST PHASE II AND OUR COSMOLOGICAL AXION MASS LIMIT PROBABLY CONNECT.
ga < 8.8 x 10-11 GeV-1 at 95% CL for ma < 0.02 eV
LIMITS FROM CAST-I AND CAST-II
CAST-I
ga < 2.2 x 10-10 GeV-1 at 95% CL for ma < 0.39 eV
CAST-II (Preliminary)
CONCLUSIONS
• For hadronic axions we find a new mass limit ma < 1 eV (95% CL), corresponding to fa> 5.7×106 GeV.
• It is comparable with the (model-dependent) limit obtained with the globular clusters.
• It closes the “hadronic axion” window.
• It is nicely complementary with the CAST search.
• If neutrino masses are detected in laboratory (KATRIN) : Less room for axions in the dark matter inventory.
Observations of the cosmological large-scale structure provide well-estabilished neutrino mass limit. We extend this argument to thermal relic axions:
Alessandro Mirizzi NOW 2008 Conca Specchiulla, 6-13 September 2008