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### The Growth factor: degeneracy of Neutrinos Mass and Dark Energy

### DES Forecasts: Power of Multiple Techniques

Neutrino Masses from the CMB

(III) The Dark Energy Survey

Ofer Lahav

University College London

Concordance Cosmology

- SN Ia
- CMB
- LSS – Baryonic Oscillations
- Cluster counts
- Weak Lensing
- Integrated Sachs Wolfe

Physical effects:

* Geometry

* Growth of Structure

Massive Neutrinos and Cosmology

* Why bother? – absolute mass, effect on other parameters

* Brief history of ‘Hot Dark Matter’

* Limits on the total Neutrino mass from cosmology within CDM

M < 1 eV

* Mixed Dark Matter?

* Non-linear power spectrum and biasing – halo model

* Combined cosmological observations and laboratory experiments

Brief History of ‘Hot Dark Matter’

- *1970s : Top-down scenario with massive neutrinos (HDM) –
- Zeldovich Pancakes
- *1980s: HDM - Problems with structure formation
- *1990s: Mixed CDM (80%) + HDM (20% )
- * 2000s: Baryons (4%) + CDM (26%) +Lambda (70%):
- But now we know HDM exists!
- How much?

Globalisation and the New Cosmology

- How is the New Cosmology affected by Globalisation?
- Recall the Cold War era:

Hot Dark Matter/top-down (East)

vs. Cold Dark Matter/bottom-up (West)

- Is the agreement on the `concordance model’ a product of Globalisation?

OL, astro-ph/0610713

Neutrinos decoupled when they were still relativistic, hence they wiped out structure on small scales

k > knr = 0.026 (m /1 eV)1/2m1/2 h/Mpc

Colombi, Dodelson, & Widrow 1995

CDM

CDM+HDM

WDM

Massive neutrinos mimic

a smaller source term

Neutrino properties

Thenumber of neutrino species Nn affects

the expansion rate of the universe, hence BBN.

BBN constraints Nn between 1.7 and 3 (95% CL)

(e.g. Barger et al. 2003).

From CMB+LSS+SN Ia, N =4.2+1.2-1.7(95% CL)

(Hannestad 2005)

We shall assume Nn =3

Electron, muon and tau neutrinos

Eigen states m1, m2, m3

112 neutrinos per cm3

Wnh2 = Mn/(94 eV)

Absolute Masses of Neutrinos

Based on

measured

squared mass

differences

from solar and

atmospheric

oscillations

Assuming

m1 <m2 <m3

E & L, NJP 05

Kiakotou, Elgaroy, OL

Weighing Neutrinos with 2dFGRS

- Free streaming effect:
- Wn/Wm< 0.13

Total n mass M< 1.8 eV

- 0.001 < Wn < 0.04

(Oscillations) (2dF)

- a Four-Component Universe ?

Wn= 0.05

0.01

0.00

Elgaroy , Lahav & 2dFGRS team,

astro-ph/0204152 , PRL

What do we mean by ‘systematic uncertainties’?

- Cosmological (parameters and priors)
- Astrophysical (e.g. Galaxy biasing)
- Instrumental (e.g. ‘seeing’)

Biasing vs. neutrino mass

Pg(k) = b2(k) Pm(k)

b(k) = a log(k) + c

a

---- SAM for

L>0.75 L*

Total neutrino mass

Elgaroy & Lahav , JCAP, astro-ph/030389

Non-linear P(k) with massive neutrinos

Abazajian et al. (astro-ph/0411552)

modeled the effects of neutrino infall

into CDM halos

and incorporated it in the halo model.

The effect is small: P(k)/P(k) » 1%

at k » 0.5 h/Mpc for M» 1 eV

Future work : high-resolution simulations

with CDM, baryons and neutrinos

Neutrinos masses and the CMB

If znr > zrec

h2 > 0.017 (i.e. M > 1.6 eV)

Then neutrinos behave like matter -

this defines a critical value in CMB features

* Ichikawa et al. (2004 )

from WMAP1 alone M < 2.0 eV

* Fukugita et al. (2006)

from WMAP3 alone M < 2.0 eV

Normalization vs neutrino mass using WMAP alone + concordance model

Is CMB polarisation useful for neutrino mass?

Fukugita, Ichikawa,

Kawasaki, OL, astro-ph/0605362

Not directly,

but reduces degeneracy with

the reionization optical depth

Deriving Neutrino mass from Cosmology

All upper limits 95% CL, but different assumed priors !

Forecasting Neutrino mass from Cosmology

Note different error definitions and assumed priors !

Neutrinos - Summary

* Redshift surveys (+ CMB) Mn < 0.7-1.8 eV

Ly- (+ CMB+LSS) Mn < 0.17 eV

* Within the L-CDM scenarios, subject to

priors.

* Alternatives: MDM ruled out.

* Future: errors down to 0.05 eV

using SDSS+Planck,

and weak gravitational lensing of background galaxies and of the CMB.

Resolve the neutrino absolute mass!

Filters

Depth

Dates

Status

Sq. Degrees

CTIO

75

1

shallow

published

VIRMOS

9

1

moderate

published

COSMOS

2 (space)

1

moderate

complete

36

4

deep

complete

DLS (NOAO)

Subaru

30?

1?

deep

observing

2005?

170

5

moderate

observing

CFH Legacy

2004-2008

830

3

shallow

approved

RCS2 (CFH)

2005-2007

VST/KIDS/

VISTA/VIKING

1700

4+5

moderate

2007-2010?

50%approved

5000

4

moderate

proposed

DES (NOAO)

2008-2012?

Pan-STARRS

~10,000?

5?

moderate

~funded

2006-2012?

LSST

15,000?

5?

deep

proposed

2014-2024?

1000+ (space)

9

deep

proposed

JDEM/SNAP

2013-2018?

Imaging Surveysproposed

moderate

5000?

4+5

2010-2015?

VST/VISTA

proposed

moderate

2+1?

DUNE

20000? (space)

2012-2018?

Y.

Y. Mellier

DUNE: Dark UNiverse Explorer

- Mission baseline:
- 1.2m telescope
- FOV 0.5 deg2
- PSF FWHM 0.23’’
- Pixels 0.11’’
- GEO (or HEO) orbit
- Surveys (3-year initial programme):
- WL survey: 20,000 deg2 in 1 red broad band, 35 galaxies/amin2 with median z ~ 1, ground based complement for photo-z’s
- Near-IR survey (J,H). Deeper than possible from ground. Secures z > 1 photo-z’s
- SNe survey: 2x60 deg2, observed for 9 months each every 4 days in 6 bands, 10000 SNe out to z ~ 1.5, ground based spectroscopy

Photometric redshift

- Probe strong spectral features (4000 break)
- Difference in flux through filters as the galaxy is redshifted.

*Training on ~13,000 2SLAQ*Generating with ANNz Photo-z for ~1,000,000 LRGsMegaZ-LRG

z = 0.046

Collister, Lahav,

Blake et al.,

astro-ph/0607630

Blake, Collister, Bridle & Lahav; astro-ph/0605303

The Dark Energy Survey

Blanco 4-meter at CTIO

- Study Dark Energy using

4 complementary techniques:

I. Cluster Counts

II. Weak Lensing

III. Baryon Acoustic Oscillations

IV. Supernovae

• Two multi-band surveys

5000 deg2g, r, i, z

40 deg2 repeat (SNe)

• Build new 3 deg2 camera

and data management system

Survey 2010-2015 (525 nights)

Response to NOAO AO

300,000,000 photometric redshifts

The DES Collaboration

Fermilab: J. Annis, H. T. Diehl, S. Dodelson, J. Estrada, B. Flaugher, J. Frieman, S. Kent, H. Lin, P. Limon, K. W. Merritt, J. Peoples, V. Scarpine, A. Stebbins,

C. Stoughton, D. Tucker, W. Wester

University of Illinois at Urbana-Champaign: C. Beldica, R. Brunner, I. Karliner, J. Mohr, R. Plante, P. Ricker, M. Selen, J. Thaler

University of Chicago:J. Carlstrom, S. Dodelson, J. Frieman, M. Gladders,

W. Hu, S. Kent, R. Kessler, E. Sheldon, R. Wechsler

Lawrence Berkeley National Lab: N. Roe, C. Bebek, M. Levi, S. Perlmutter

University of Michigan: R. Bernstein, B. Bigelow, M. Campbell, D. Gerdes, A. Evrard, W. Lorenzon, T. McKay, M. Schubnell, G. Tarle, M. Tecchio

NOAO/CTIO: T. Abbott, C. Miller, C. Smith, N. Suntzeff, A. Walker

CSIC/Institut d\'Estudis Espacials de Catalunya (Barcelona):F. Castander, P. Fosalba, E. Gaztañaga, J. Miralda-Escude

Institut de Fisica d\'Altes Energies (Barcelona):E. Fernández, M. Martínez

CIEMAT (Madrid): C. Mana, M. Molla, E. Sanchez, J. Garcia-Bellido

University College London: O. Lahav, D. Brooks, P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller

University of Cambridge:G. Efstathiou, R. McMahon, W. Sutherland

University of Edinburgh:J. Peacock

University of Portsmouth: R. Crittenden, R. Nichol, R. Maartnes, W. Percival

University of Sussex: A. Liddle, K. Romer

plus postdocs and students

The Dark Energy Survey UK Consortium

(I) PPARC funding:

O. Lahav (PI), P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller (UCL),

R. Nichol (Portsmouth), G. Efstathiou, R. McMahon, W. Sutherland (Cambridge)

J. Peacock (Edinburgh)

Submitted a proposal to PPARC requesting £ 1.7M for the DES optical design.

In March 2006, PPARC Council announced that

it “will seek participation in DES”.

PPARC already approved £220K for current R&D.

(II) SRIF3 funding:

R. Nichol, R. Crittenden, R. Maartens, W. Percival (ICG Portsmouth)

K. Romer, A. Liddle (Sussex)

Funding the optical glass blanks for the UCL DES optical work

These scientists will work together through the UK DES Consortium.

Other DES proposals are under consideration by

US and Spanish funding agencies.

w(z) =w0+wa(1–a) 68% CL

Assumptions:

Clusters:

8=0.75, zmax=1.5,

WL mass calibration

BAO:lmax=300

WL:lmax=1000

(no bispectrum)

Statistical+photo-z

systematic errors only

Spatial curvature, galaxy bias

marginalized,

Planck CMB prior

Factor 4.6 improvement over Stage II

DETF Figure of

Merit: inverse

area of ellipse

DES z=0.8 photo-z shell

Mn

0.0 eV

0.4

0.9

1.7

Back of the envelope: improved by sqrt (volume) => Sub-eV from DES

(OL, Abdalla, Black; in prep)

DES and a Dark Energy Programme

- * 4-5 complementary probes
- * Survey strategy delivers substantial DE science after 2 years
- * Relatively modest (~ $20-30M), low-risk, near-term project with high discovery potential
- *Synergy with SPT and VISTA on the DETF Stage III timescale
- * Scientific and technical precursor to the more ambitious Stage IV Dark Energy projects to follow: LSST and JDEM

Some Outstanding Questions:

* Vacuum energy

(cosmological constant, w= -1.000 after all ?)

* Dynamical scalar field ?

* Modified gravity ?

* Why /m = 3 ?

* Non-zero Neutrino mass < 1eV ?

* The exact value of the spectral index: n < 1 ?

* Excess power on large scales ?

* Is the curvature zero exactly ?

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