Absolute Neutrino Mass from Cosmology. Manoj Kaplinghat UC Davis

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1 Absolute Neutrino Mass from Cosmology Manoj Kaplinghat UC Davis

2 Kinematic Constraints on Neutrino Mass Tritium decay (Mainz Collaboration, Bloom et al, Nucl. Phys. B91, 273, 2001) p and t decay

3 Future of Laboratory Constraints Kinematic: KATRIN Aim: m ne < 0.35 ev at 95% CL. Double beta decay: Proposed reach 0.05 ev Typical sources ~ 1 ton Issues: Background and theoretical uncertainties Many proposals: CUORE, EXO, GENIUS, MAJORANA, MOON, Double beta decay experiments only probe majorana mass terms

4 Neutrino Oscillation Summary Super-Kamiokande, K2K Atmospheric n m oscillations dm 2 ~ (0.07 ev) 2 Mixing ~ Maximal SNO, Kamland Solar n e oscillations dm 2 ~ (0.007 ev) 2 Mixing ~ Large LSND?, MiniBoone Electron anti-neutrino appearance dm 2 ~ ev 2 Mixing ~ Small If LSND is right, a fourth sterile neutrino is required. This is probably not populated in cosmologically relevant amounts.

5 Mass Schemes and 50 milli-ev Atm LSND LSND Atm Sol Sol At least one active neutrino with mass greater than ~ 0.05 ev At least one active neutrino with mass greater than ~ 0.3 ev We can probe this regime in the lab and the cosmos.

6 Massive Neutrinos and Cosmology: Outline Early Phase BBN Primary CMB Lensed CMB Lensing Galaxies Galaxy Shear

7 Neutrinos and Big Bang Nucleosynthesis Increase N n Speed-up Expansion rate Larger n/p 4 He and D/H increase 1.7 < N n < 3.5 (95%) ) sterile n (if it exists) must not thermalize. Both 2+2 and 3+1 schemes disfavored. K. N. Abazajian, Astropart. Phys. 19 (2003) 303

8 Massive Neutrino and Primary CMB Damping length increases less than sound horizon and hence the effective damping is smaller. Peaks have more power. Expansion rate at early times smaller. Angle subtended by sound horizon at LSS larger. Peaks move to the left. Presence of a not quite non-relativistic neutrino at LSS causes gravitational potential decay boosting the first peak height.

9 Massive Neutrino and Matter Power Spectrum k J (EQ) H 0 k J (now)

10 Jeans Instability for Neutrinos Neutrino perturbations on length scales larger than the Jeans length become unstable and collapse into dark matter potential wells.

11 Neutrino Mass from Galaxies The matter power spectrum measured using galaxy surveys can be used together with CMB experiments to determine the neutrino mass. Sloan Digital Sky Survey and WMAP together can measure the neutrino mass at 2s if where N is the number of neutrinos with degenerate mass m n. Hu, Eisenstein and Tegmark, PRL 80 (1998) 5255

12 WMAP Limit on Neutrino Mass WMAP team put a stringent bound on the sum of the neutrino masses. The combination of WMAP, CBI, ACBAR (CMB experiments) and 2dFGRS (galaxy survey) yields at 95% CL For a single massive neutrino this implies For three degenerate massive neutrinos this implies

13 A Preference for Non-Zero Neutrino Mass Allen, Schmidt and Bridle, MNRAS, 2003 combined CMB, 2dF, Gas fraction in X-ray clusters and X-ray cluster luminosity function measurements. The data prefer a non-zero neutrino mass at the 2s level. The likely value for the sum of neutrino masses from the analysis of Allen, Schmidt and Bridle is 0.6 ev or 0.2 ev for three degenerate neutrinos.

14 Future Early Phase BBN Primary CMB Lensed CMB Lensing Galaxies Galaxy Shear

15 Lensing of the CMB Lensing softens the exponential drop-off of primary CMB signal due to Silk damping. Mixes E and B mode polarization. Zaldarriaga and Seljak 1998 Lensing potential Hu and Okamoto, ApJ 574, 566 (2002) Lensing potential can probe fundamental physics.

16 Coherence of Lensing Deflection Peak sensitivity ~ z=2 Coherence ~ 10 degrees

17 Method Fisher Matrix approach. Unlensed temperature and polarization spectra. Lensing information added through the power spectrum of the deflection angle (lensing potential). Important to choose parameter set carefully. Jungman, Kamionkowski, Kosowksy and Spergel, PRD 54, 1332 (1996) Eisenstein, Hu and Tegmark, ApJ 518, 2 (1999) Efstathiou and Bond, MNRAS 304, 75 (1999) Hu, Fukugita, Zaldarriaga and Tegmark, ApJ 549, 669 (2001) Kosowsky, Milosavljevic and Jimenez, PRD 66, (2002)

18 Experiments Planck 100, 143 and 217 GHz channels. For a single massive neutrino CMBpol 1 mk per pixel. Angular resolution 3 arcminutes. One channel at 217 GHz. Full Sky. For a single massive neutrino

19 Fundamental Physics with Future CMB Data Alone Of Direct Relevance to Inflation: Gravity waves from Inflation. Precision measure of the amplitude of the scalar perturbations to 1%. Tilt and its variation with scale. Vital for differentiating between models of inflation. Others: Detect the acceleration of the universe at 3s independent of supernova Ia observations. Map reionization history. Kaplinghat, Knox and Song, 2003

20 Galaxy Lensing Tomography Weak lensing distorts the shape of galaxies. This distortion is measurable when averaged over a large number of galaxies. The distortion (shear) depends on the projected mass density along the photon s geodesic. Look at the shear of galaxies in specific redshift bins. This provides the redshift evolution of the projected mass density. Hu ApJ, 522, 21 (1999) Hu and Keeton, PRD 66, (2002) Hu, PRD 66, (2002)

21 Prospects The projected mass density depends (among other things) on dark energy and neutrino mass. In order to extract the neutrino mass, the power spectrum at early times (LSS) has to be well constrained. With a deep survey over 10% of the sky, it is possible to constrain the mass of a single massive neutrino with a precision of Lensing tomography also provides an independent test of the acceleration of the universe Abazajian and Dodelson, PRL, 2003

22 Summary It is possible to measure the absolute neutrino mass with an accuracy of 0.05 ev with different techniques. Cosmological probes: Lensing of the CMB and galaxies. Laboratory: Double beta decay experiments.