Subject: LSST can measure the neutrino mass

From: Jon Thaler

Submitted: Tue, 01 Jul 2003 17:52:42 -0500

Message number: 132 (previous: 131, next: 133 up: Index)

Hi,

I suggest that the SWG consider the possibility that the LSST might 
make the first measurement of the neutrino mass.  The present limits 
are:

* m(nu) > 0.04 eV
   From nu oscillations (at least one nu must be at least this massive), 
and

* m(nu) < 0.69 eV
   From large scale structure (2dF combined with WMAP - the sum of the 
nu masses)
   See: Ø. Elgarøy,  et al.,  Phys. Rev. Lett. 89, 06130 (2002), and
   "Parameter Estimation Methodology" and "Determination of Cosmological 
Parameters" on
   http://map.gsfc.nasa.gov/m_mm/pub_papers/firstyear.html

Particle physics experiments are not likely to push these limits 
together in the near future.  The lower limit cannot be improved, 
because oscillations don't set the absolute mass scale.  The upper 
limit requires difficult (and theory limited) neutrinoless double-beta 
decay experiments.

It has been suggested that CMB polarization measurements can do the job 
(see Kaplinghat, Knox and Song - astro-ph 0303344), but Planck will 
only get to 0.14 eV.  A next generation polarization experiment 
(CMBpol) could get to 0.03 eV.

The 2dF/WMAP result is limited by statistics (160,000 galaxies) and 
angular coverage.  SDSS will have about twice as many galaxies and 
better coverage.  LSST will have more than 1000 times the statistics 
and better yet coverage, so a naive scaling says that, unless 
systematic problems dominate, we should have enough sensitivity to see 
the effect of nonrelativistic neutrinos.

I will begin to study this issue when a new student arrives in August.

Jon

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