THE DARK SIDE

Open problems withDark Matter & Dark Energy

A review and tentative solutions

Silvio BonomettoDep. Physics G.OcchialiniMilano-Bicocca LNGS – September 2005

Roberto MaininiLoris Colombo Dip.Fisica G.Occhialini Milano-Bicocca

Andrea Maccio’ Theor.Physics University of Zurich

Alessandro Gardini IllinoisGiuseppe Murante TorinoSebastiano Ghigna ? ? Elena Pierpaoli Caltech Stefano Borgani Trieste……….

In collaboration with

Problems with DM• WHY there must be (non-barionic) DM• Halo numerical profiles (NFW) also vs observed profiles• Galaxy satellite abundance

Problems with DE• WHY there must be DE• Fine tuning problems (56 o.m.)• Coincidence problems In particular: Why DE density ~ DM density just today ?

A twofold aim

(1) Describing current problems, namely those related to LSS

(2) Introducing “dual axion” model Same # of parameters as SCDM

Cosmological Parameters in all models

N(photons)/N(baryons)Density/Critical DensityCDM Density/Baryon density

SCDM :these

param-eters

LCDM cosmology 1 extra parameter: Matter density/Critical density

Dynamical DE (+ 1 parameter)Coupled DE (+2 parameter)

baryogenesisgeometry

mb

Underlying ideology: Should astrophysics put limits on extra parameters new physics discovered and constrained

Even better: (new) physics requires DE & DM, setting their parameters in the fair range: A MICROPHYSICAL WAY OUT FROM FINE TUNING & COINCIDENCE

An alternative view (Kolb,Riotto,Matarrese,…2005see also Buckert 1980, Ellis 1990 …)

g=+hstandrd defined by a() & coming from assigned state eqs. (p=w) h initially linear, then developing non-linearities new h initially linear when extreme non-linear. developed backg.state eqn modified

Microph.solution

Geometr.solution

covariant form

Standard approach to cosmology

conformal time

smoothing

Stress-energy tensorpseudoconservation

in space,not in time !

Stress-energypseudoconservationeqn can be solvedwithout knowing

a(

Scalar field lagrangian

Brax & Martin, 1999, 2001Brax, Martin & Riazuelo 2000

Major problem withDark Energy

Consistent with CMB data

5641144

,,

4,

44,

10)10/10(10

/

10

eVeV

T

T

ewvacovac

ewewvac

oovac

DE, at earlytimes, just

subdominant

Dominantradiat. or DM

fulfilling equation = wp

for DE comp.

A further possibilityconcerning scalar field

Exploit its phase…

Newpotential

term

V1()New eqs of

motion

Potentialenergy also

for

NO PRESSUREDM

COUPLING

A shortdiscussionof theseclassical

argument

Milky Way reconstruction

OPTICAL RADIUS

SPIRAL ARMS

CORE

BRILLIANCEEQUATES THE

NIGHT SKY

notice the bar

Spiral arms: density waves in theEXPONENTIAL DISK

)/exp()( rr o

Optical radius ro ~ ROTATION CURVEv(r) increasing almost up to optical radiusKeplerian region expected

21cm radio data : NO FALL up to ~7-8 times the optical radius

Dark Matter massup to 7-8 times (or more)the visible mass

=2 M prop R

If 21cm rotation curveextends ~10 times opt radthen M ~ 10 Moptical

From ngal andmass in Stars, dust, gas, etc:

b ~ 0.01

IF TOTAL MASS IS 10 TIMES BARYONIC MASSBBNS FORBIDS ITS BEING

BARYONIC

Virial theorem extensively used

R

MGv 2

both to analyse cosmic objectsand to compare then with theoretical or numerical predictions

USE IT NOWFOR GALAXYCLUSTERS

e.g.you don’t give

M or R for small galaxies, but their m.s.v.

Large galaxycluster, optical imageM ~ 10^15 Msun

Notice stronglensing -> Mcl

In agreement with mass from virial equilibrium

~10 times baryon mass in gal. + X-ray emitting

hot gasm > 0.10-0.15

Spherical top-hat fluctuat. growth vs. a(t):analyt. solutionin SCDM cosm.

Cluster formby action ofpure gravity

Energy conservation + virial equilibrium

Rfinal=0.5 Rtop (SCDM)

Top expansion :density contrast ~15

Virialization :density contrast

~180

virtop

virvirvirtop

virvirtop

virvirvir

RR

RGMTRGMRGM

UTUconserven

RGMUTeqlmvirial

2

2///

:..

/2:

Further contraction requires heat dissipation. This happens when galaxies form. Dissipative forceshave no role in cluster shaping

Not unique value, but distribution (normal)

Understanding CMB and deep sample data

More detailsin nextpages

lC spectra

Adiabatic& isocurvature(isothermal)

Coupling C(also C=0)

Linear Fluctuations :At early timesor over verylarge scale

today

Understanding CMB and deep sample data

Expansion in harmonics is an essential ingredientof any numerical calculation of anisotropy and

polarization of CMB; it is unessential to computetransfer functions (see below)

baryons :

photons : Holdingwhen photons and baryons

are strictly coupled, orwhen coupling just begins

to fade

massless neutrinoFluctuations: either gravitionallu

unstable, or free streaming

RADIATION& BARYON

SOUND WAVESWHILE DM

FLUCTUATIONSINCREASE

(AFTEREQUIV.)

Differentphases in waves,

when recombinationoccurs, will be visible

in tranf.funct. and Cl

DM fluctuationsgrow all the time,

but between their entry in horizon and equivalence,

if they occur inthis order

first availablewhole sky data

angularresolution7 degrees

first release of WMAP datanotice increased resolution, there is howevera good correspondence between COBE & WMAP

A short reviewon the approach

followed in order tocompare CMBR

data with models

Stockesparameters

Expansionin scalar spherical

harmonics

Expansionin spin 2 spherical

harmonics

4 rotationperiodicity

Temperaturefluctuations

E-modepolarization

T-E cor-relation

*,,,

2,,

2,,

||

||

lmElmTlTE

lmElE

lmTlT

aaC

aC

aC

How spectradepend on

optical depth

LCDM

SUGRApotentialvs WMAP

C~4mp

Bestfit param.for LCDM

cosm.

IMPORTANTTO OUTLINETHAT THESEVALUES ARETRUE WHEN

ASSUMINGA LCDM

COSMOLOGY

SUGRAas good as

LCDM

all percents

rathersimilar

(not so great)

Large values weremain WMAPdiscovery

Range of valuesdepends on the

model

b much less than m: Non-baryonic

DM needed

Also tot ~ 1

m much lessthan tot : DE needed

Results obtained with MCMC technique1 and 2-sigma confidence levels

notice howlog(GeV)almostunconstrained

A similar plot for 1/coupled cosmologiesnotice how better constrained all parametersand in particular

Varyingtotal matter

density

Varyingbaryonicdensity

the 2df sample

Numericalsimulations

NON-LINEAREVOLUTION

NUMERICAL SIMULATIONS

Wigglesdue to baryon contribution

to final amplitude

Bending due toMeszaros effect

300 Mpc

3Mpc

HIGHESTRESOLUTIONSIMULATIONOF DMHALO

Navarro 2003central profile slope indipendent onobject size

17.027.1

Diemand et al 2004/2005

NFW profile (1997)central slope -1

2

1

)(

cc

o

r

r

r

rr

Moore et al 2001central slope -1.5

Slope ofhalo profiles.A problem? Concentration,

Instead, depends on objects size : c = rc /rvc ~ 5-7 (clusters)c ~10 (galaxies)

Swaters et al 2003Swaters et al 2003

De Block et al 2001

LSB galaxiesmeasuring of the slope of the core profile

Howgalaxy rot

data are fittedco work out

centralslope

reproducingslope estimateon simulatedobjects with~NFW profile

Spekkens et al 2005

Swaters et al2003

ANDROMEDASATELLITES

Klypin et al 1999 Moore et al 1999

Where are the missing galaxy

satellites ?

2 solution: missing satellites did not form missing satellites are there, but invisible…

Bullock, Weinberg & Kravtsov 2002PopIII stars reionizethe Universe at z~8Gas infall in low-masshalos is suppressedafter reionization

Workingonly for z(reion) ~ 8If reionization earlier

mechanism fails(Maccio’ et al

2005)

~16 requires z(reion)~18

MECHANISM NEEDEDTO REMOVE BARYONSFROM SMALL HALOS

OTHER MECHANISM TO HAVE DM-ENRICHED SATELLITES REQUIRED

OTHER EVIDENCES OF DM-BARYON SEGREGATIONON OTHER SCALESe.g. THE L-T CLUSTER PROBLEM

IN THIS CASEASTROPHYSICAL SOLUTIONS PROPOSEDBUT THEIR EFFICIENCY IS STILL DISPUTED

DM-DE COUPLING PROVIDES MECHANISM FORBARYON-DM SEGREGATION

AN EVIDENCE IN FAVOR OF COUPLING WITHIN THE DARK SECTOR ?

Towards the conclusion …

Still many problemsin the dark …….