the dark side
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THE DARK SIDE. Open problems with Dark Matter & Dark Energy A review and tentative solutions. Silvio Bonometto Dep. Physics G.Occhialini Milano-Bicocca. LNGS – September 2005. In collaboration with. Roberto Mainini - PowerPoint PPT PresentationTRANSCRIPT
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THE DARK SIDE
Open problems withDark Matter & Dark Energy
A review and tentative solutions
Silvio BonomettoDep. Physics G.OcchialiniMilano-Bicocca LNGS – September 2005
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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
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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 ?
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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
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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
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covariant form
Standard approach to cosmology
conformal time
smoothing
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Stress-energy tensorpseudoconservation
in space,not in time !
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Stress-energypseudoconservationeqn can be solvedwithout knowing
a(
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Scalar field lagrangian
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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.
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A further possibilityconcerning scalar field
Exploit its phase…
Newpotential
term
V1()New eqs of
motion
Potentialenergy also
for
NO PRESSUREDM
COUPLING
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A shortdiscussionof theseclassical
argument
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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
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=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
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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.
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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
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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
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Not unique value, but distribution (normal)
Understanding CMB and deep sample data
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More detailsin nextpages
lC spectra
Adiabatic& isocurvature(isothermal)
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Coupling C(also C=0)
Linear Fluctuations :At early timesor over verylarge scale
today
Understanding CMB and deep sample data
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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
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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
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first availablewhole sky data
angularresolution7 degrees
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first release of WMAP datanotice increased resolution, there is howevera good correspondence between COBE & WMAP
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A short reviewon the approach
followed in order tocompare CMBR
data with models
Stockesparameters
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Expansionin scalar spherical
harmonics
Expansionin spin 2 spherical
harmonics
4 rotationperiodicity
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Temperaturefluctuations
E-modepolarization
T-E cor-relation
*,,,
2,,
2,,
||
||
lmElmTlTE
lmElE
lmTlT
aaC
aC
aC
How spectradepend on
optical depth
LCDM
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SUGRApotentialvs WMAP
C~4mp
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Bestfit param.for LCDM
cosm.
IMPORTANTTO OUTLINETHAT THESEVALUES ARETRUE WHEN
ASSUMINGA LCDM
COSMOLOGY
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SUGRAas good as
LCDM
all percents
rathersimilar
(not so great)
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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
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Results obtained with MCMC technique1 and 2-sigma confidence levels
notice howlog(GeV)almostunconstrained
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A similar plot for 1/coupled cosmologiesnotice how better constrained all parametersand in particular
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Varyingtotal matter
density
Varyingbaryonicdensity
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the 2df sample
Numericalsimulations
NON-LINEAREVOLUTION
NUMERICAL SIMULATIONS
Wigglesdue to baryon contribution
to final amplitude
Bending due toMeszaros effect
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300 Mpc
3Mpc
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HIGHESTRESOLUTIONSIMULATIONOF DMHALO
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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)
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Swaters et al 2003Swaters et al 2003
De Block et al 2001
LSB galaxiesmeasuring of the slope of the core profile
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Howgalaxy rot
data are fittedco work out
centralslope
reproducingslope estimateon simulatedobjects with~NFW profile
Spekkens et al 2005
Swaters et al2003
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ANDROMEDASATELLITES
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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…
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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
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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 …
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Still many problemsin the dark …….