Weighing Neutrinos including the Largest
Photometric Galaxy Survey: MegaZ DR7
“A combined constraint on the Neutrinos”
Arxiv: 0911.5291
Shaun Thomas: UCL
Moriond 2010
Outline:
1. Neutrinos have mass!
2. Neutrino signatures in cosmology
3. Probes of the Model
•
Cosmic Microwave Background
•
Galaxy Surveys
•
Supernovae and Baryon Oscillations
4. Work: Thomas, Abdalla & Lahav (2009): arXiv:0911.5291 (+ In prep. 2010)
5. For the Future…?
Shaun Thomas: UCL
Moriond 2010
Neutrino oscillations indicate they have mass!
But not on the absolute scale of mass…
For example…
• Beta-decay kinematics
KATRIN
• Neutrinoless double beta-decay
nemo
• Cosmology!
Age of precision Cosmology
Shaun Thomas: UCL
Thomas, Abdalla, Lahav (2009)
http://www-ik.fzk.de/~katrin/index.html
Not just interesting physics but,
an integral part of the cosmological model…
Moriond 2010
Signatures in the Model
• Act as radiation or matter and affect the Universe’s expansion history
• Suppress the growth of matter structure and cosmological perturbations
Neutrinos have large thermal
velocities and Free-stream out of
over-densities/inhomogeneities
thus suppressing the clustering of
matter and galaxies
Neutrino fraction is directly related to sum of masses (RHS)
Which we might see in a power spectrum…
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
Cosmic Microwave Background (CMB)
With the CMB the effect depends on whether neutrinos are relativistic or not:
• Suppress potentials - change heights of peaks OR
• Affect matter-radiation balance
Model
Data
Constraint
WMAP 5 year (CMB) : < 1.3 eV (95% CL)
Suggestive of a CMB limit ~ 1.5 eV (E.g. Ichikawa 05)
Komatsu et al. [arXiv:0803.0547]
Thomas et al. [arXiv:0911.5291]
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
E.g. Supernova Legacy Survey
Supernovae (SN)
Standard candle allows one to measure the expansion history
Tighter matter/hubble constraint aids neutrino determination
Baryon Acoustic Oscillations (BAOs)
E.g. Percival et al
Primordial CMB photon-baryon oscillations are imprinted
onto late-time matter power spectrum: BAO
Standard ruler allows one to measure the expansion history
Tighter matter/hubble constraint aids neutrino determination
CMB + SN + BAO : < 0.69 eV
(95% CL)
Komatsu et al. [arXiv:0803.0547]
Thomas et al. [arXiv:0911.5291]
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
+ Galaxy Clustering!
Sloan Digital Sky Survey (SDSS)
• Suppress the growth of matter structure and cosmological perturbations
Smaller Scales
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
+ Galaxy Clustering!
Sloan Digital Sky Survey (SDSS)
Luminous Red Galaxies (LRGs)
Largest galaxy survey
723,556 LRGs
7,746 square degrees
Photometric Redshift
0.45 < z < 0.65
Volume: 3.3 (Gpc /h)^3
Four redshift bins
Thomas, Abdalla
Padmanabhan
et &
al.Lahav
2007 - in prep
ANNz - Collister and Lahav 2004
2SLAQ - 13’000 spectroscopic training/evaluation set
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
+ Galaxy Clustering!
Sloan Digital Sky Survey (SDSS)
MegaZ DR7
One of the largest galaxy surveys to date
Thomas, Abdalla & Lahav - in prep
Including the production of a new SDSS galaxy clustering angular power spectra
We can use this with the BAO(!) - Improves combined neutrino constraint further!
Shaun Thomas: UCL
Moriond 2010
Probes of Cosmology
+ Galaxy Clustering!
Sloan Digital Sky Survey (SDSS)
4 bins: 0.45 < z < 0.65
Luminous Red Galaxies (LRGS)
Max multipole l=300
MegaZ DR7

12 Parameters:
b h 2;c h 2; ;;ns;ln(1010 As );m ;ASZ ;b1;b2;b3;b4
Shaun Thomas: UCL
CMB + SN + BAO + SDSS LRGs + HST: < 0.28 eV
(95% CL)
Thomas et al. [arXiv:0911.5291]
Moriond 2010
Cosmology and Neutrinos
Komatsu et al. [arXiv:0803.0547] < 1.3 eV (CMB)
Tereno et al. [arXiv:0810.0555]
< 0.67 eV (CMB+SN+BAO)
< 0.54 eV
(CMB+SN+BAO+WL)
Ichiki, Takada & Takahashi [arXiv:0810.4921] < 0.54 eV
(CMB+SN+BAO+WL)
Seljak et al. [arXiv:0604335]
(+ Lyman Alpha…)
< 0.17 eV
Systematics - e.g. winds?
CMB + SN + BAO + SDSS LRGs +HST
Thomas, Abdalla & Lahav [0911.5291]
Using all the aforementioned probes for
complementary data constraint
CMB+SDSS+SN+BAO+HST
0.28 eV
Recent BAO data and production of newest galaxy
clustering angular power spectrum
With luminous Red Galaxies (LRGs)
sampling a large cosmic volume
Cosmology is starting to predict that experiments such as KATRIN (mentioned earlier) will not detect anything
Shaun Thomas: UCL
Moriond 2010
WOOHOO!
Shaun Thomas: UCL
Moriond 2010
‘Systematics and Limitations’
Work for the Future…
Cosmology = Good 
Although we want tighter neutrino constraints
We also want trustworthy neutrino constraints.
However
Galaxy Bias
Model underlying matter power
spectrum but measure the
galaxy power spectrum
Scale dependence…mimic…?
Non-linearities
Parameter Degeneracies
Bias result or lose data
Perturbation theory/
N-body simulations
Most quoted results assume
cosmological constant
cosmology
Degeneracy with w increases
error bar
E.g. Saito et al 09
Brandbyge & Hannestad 09
L_max = 300 =>
0.28 eV
L_max = 200 =>
0.34 eV
Work In Progress…
E.g. Hannestad
Shaun Thomas: UCL
Moriond 2010
Summary
• Cosmology is a sensitive neutrino experiment! (Funded billions of years ago!)
• Massive neutrinos suppress the growth of structure
• Probes such as galaxy clustering or weak lensing are sensitive to growth
• Integral part of cosmological model and parameter space
• Have a complete complementary constraint on neutrinos (sub eV region)
Having produced data for a tighter constraint
• Systematics and limitations still exist though…
Tighter neutrino constraint. Trustworthy neutrino constraint.
• The Future is promising but with work to be done…
Shaun Thomas: UCL
Moriond 2010
Related and Further Reading
Cosmology and Neutrinos
Thomas, Abdalla & Lahav [arXiv:0911.5291]
Komatsu et al. [arXiv:0803.0547]
Thank You for Listening!
:)
Tereno et al. [arXiv:0810.0555]
Elgaroy and Lahav [arXiv:0606007]
Seljak et al. [arXiv:0604335]
Brandbyge & Hannestad [arxiv:0812.3149]
Saito et al [arxiv:0907.2922]
Galaxy Clustering
Thomas, Abdalla & Lahav (In Prep. (v. soon))
Neutrino Experiments
NEMO [arXiv:0810.5497]
KATRIN
Contact: sat@star.ucl.ac.uk
Shaun Thomas: UCL
Moriond 2010
Simulation - testing the code by
reconstructing input cosmology
Evaluated the previous DR4
release which was consistent
with Blake et al. (MegaZ DR4)
Shaun Thomas: UCL
1,2
1,4
1,3
Shaun Thomas: UCL
2,3
2,4
3,4
Shaun Thomas: UCL
Mixing matrix profile
Little correlation between multipole
bands introduced by partial sky after
binning
Shaun Thomas: UCL
Excess Power
Shaun Thomas: UCL
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