Astrophysical Constraints
on Dark Matter:
Warm or Cold ?
Charling TAO
CPPM, IN2P3, France
Tsinghua Center for Astrophysics, Tsinghua University, China
Cooks’ Branch workshop on SN, april 2012
Euclid, an ESA M-class mission
A geometrical probe of the universe proposed for Cosmic Vision
All-sky optical
imaging for
gravitational
lensing
=
+
All-sky near-IR
spectra to H=22
for BAO
The Euclid Concept
• Named in honour of the pioneer of geometry
• Euclid will survey the extra-galactic sky (15 000 deg2) to
simultaneously measure its two principal dark energy probes:
– Weak lensing:
• Diffraction limited galaxy shape measurements in one
broad visible R/I/Z band.
• Redshift determination by photo-z measurements in 3
YJH NIR bands to H(AB)=24 mag, 5σ point source
– Baryonic Acoustic Oscillations:
• Spectroscopic redshifts for 33% of all galaxies brighter
than H(AB)=22 mag, σz<0.006
• With constraints:
– Aperture: max 1.2 m diameter
– Mission duration: ~ 6 years,…
In october 2011, we have been chosen over PLATO for launch in 2019
Official (financial) approval expected June 2012
Euclid and SN?
About 20 people in SN WG
Leads: I. Hook, E. Capellaro, CT
Use opportunity of NIR YJH filters in space
(no atmospheric transmission)!
Challenge : propose best possible SN survey within
existing constraints
Dedicated Deep Survey for 6 months at end of mission (2024-?) or other
options under study (survey strategy, choice of fields, calibrations,…)
Synergy with Pan-Starrs, LSST,JWST, Antarctica, …?
to develop if we can have an independent DS field
A mysterious Dark Universe with DE and DM !
What we know is
only
4%
of the energy
density of the
Universe
We measure with
precision the
extent of our
ignorance!
An exciting lesson in
humility !
Concordance Model LCDM
Graph source: Wikipedia
Before 2000: Nature of DM
Hot or Cold?
CDM is non-relativistic
at decoupling, forms
structures in a hierarchical,
bottom-up scenario.
HDM is tightly bound by
observations
and LSS formation
LSS structures
N-Body Simulations LSS favour LCDM
OMEGA = 0.3
LAMBDA = 0.7
H0 = 70 km/(Mpc sec)
Sigma8 = 0.9
OMEGA = 1
LAMBDA =0
H0 = 50 km/(Mpc sec)
Sigma8 = 0.51
OMEGA = 1
LAMBDA =0
H0 = 50 km/(Mpc sec)
Sigma8 = 0.51
OMEGA = 0.3
LAMBDA = 0
H0 = 70 km/(Mpc sec)
Sigma8 = 0.85
VIRGO Consortium 1996
Boxsize 239.5 Mpc/h, 2563 particles
http://www.mpa-garching.mpg.de/~virgo/virgo/
~2000 :Problems with CDM at small scales
Comparing more data with more
precise N-body hydrodynamical
simulations
• Number of galactic satellites
• cusp/core at GC
Too low number of visible satellite galaxies?
Satellite galaxies are seen in Milky Way, e.g. Saggittarius, MCs
Predicted number
Observed number
of luminous
satellite galaxies
10km/s
20km/s
100km/s
Dark matter distribution—Density profiles
Cusp
Universal Density Profile
NFW
Navarro, Frenk, White 1996
Salucci &
Frigerio Martins
2009
DM Cores in Dwarf galaxies
Oh et al. 2011
Data prefer
Burkert Core Profile
Galaxy core vs cusp
Salucci & Frigerio Martins, 2009
Alternatives to CDM
• Self-Interacting Dark Matter (Spergel & Steinhardt 2000)
• Strongly Interacting Massive Particle
• Annihilating DM
• Decaying DM
• Fuzzy DM
• WDM: reduce the small scale power
WDM vs CDM
Velocity function
Density profile
From Jing 2000
Nature of DM
Hot or Cold, or Warm?
CDM is non-relativistic
at decoupling, forms
structures in a hierarchical,
bottom-up scenario.
HDM is tightly bound by
observations
and LSS formation
WDM?
But doubts on
Lya results
by SDSS
people!
A fashionable candidate
Sterile neutrinos
Constraints on sterile neutrinos
Limits on mass of WDM particles
• Stellar dynamics in MW satellites (Boyanovsky, de Vega, Sanchez 2008;
de Vega and Sanchez 2009)
• High-z QSO LF (e.g. Song and Lee 2009)
• Ly-alpha forest to constrain P(k) at small scales and different z’s
(Most popular method: Narayanan et al 2000; Viel et al 2005;2008)
• Ly-a + SDSS results (Boyarsky et al 2009)
• QSO lensing ( Miranda & Maccio 2007 )
• Abundance of dwarf satellites of MW (Maccio & Fontanot 2010;
Polysensky & Ricotti, 2010)
 Mass WDM ~ 1- 5 keV
Cosmic shear power spectra
Markovic et al. 2010
Euclid-like DE space survey+Planck:
Sensitive to m_WDM < 2.5 keV
Nonthermal production of dark matter
h 
2
Non thermal production in the
early universe,
Large annihilation cross section,
Large velocity depresses the
small scale structure.
Possible constraints from galactic
center gamma-ray
Lin, Huang, Zhang, Brandenberger, PRL86,954
(2001)
Bi, Brandenberger, Gondolo, Li, Yuan, Zhang,
0905.1253
CDM scenario with WDM?
3  10
 27
v
3
cm s
Tf
1
“Evidence” for WDM ?
•''cusp-core problem'',
•"missing satellite problem'',
Hot topic, eg
WARM DARK MATTER IN THE
GALAXIES:
THEORETICAL AND OBSERVATIONAL
PROGRESSES
CIAS Observatoire de Paris, Château de
Meudon, Meudon campus
8, 9 and 10 June 2011
CLUES simulations, Yepes, 2010
Velocity widths in Galaxies
Velocity widths in galaxies from 21 cm HI surveys
Papastergis et al, 2011; Zavala et al., 2009
NB: The red curve is for 1 keV WDM
Or inability of HI to trace the maximum halo rotational velocity of
low-mass systems?
CDM vs WDM: HI velocity functions
Virgo and Anti Virgo directions
arXiv:1005.2687: Constrained Local
UniversE Simulations (CLUES)
Gottloeber, Hoffman , Yepes
« No simple feedback
mechanism to explain
the factor 10 depletion
from CDM » ?
“Evidence” for WDM ?
•"missing satellite problem'',
•''cusp-core problem'',
• mini-voids The sizes of mini-voids in the local universe: an argument
in favor of a warm dark matter model? Tikhonov et al.
•HI determinations of velocity function profiles
N-Body simulation Comparisons with Virgo results by Arecibo Legacy
(ALFALFA)
“Evidence” for WDM ?
•"missing satellite problem'',
•''cusp-core problem'',
• mini-voids The sizes of mini-voids in the local universe: an argument
in favor of a warm dark matter model? Tikhonov et al.
•HI determinations of velocity function profiles
N-Body simulation Comparisons with Virgo results by Arecibo Legacy
(ALFALFA)
• Detection of 2.5 keV X-ray from dark dwarf galaxy?
Before we get too
depressed
or excited
…
Before we get too
depressed
or excited
•
Do not trust fashion fads !
•
How much can one trust N-Body simulations?
•
Beware of data analysis bias ! Blind analysis?
…
Strong Reliance on N-body simulations
eg Gao et al., Jing et al., Yepes et al.,
WDM and CDM simulations.
- Non-linear collapse of WDM structures
- A replacement for the NFW model (WDM)
- Effects of Baryons
LCDM Dark matter halo profile
from N-Body simulations Cusps?
Old CDM Simulations  cusps
(Navarro, Frenk, White 1996):
The latest cosmological N-body simulations find two intriguing
properties for dark matter haloes:
(1) their radial density profile, ρ, is better fit by a form that flattens
to a constant at the halo center (the Einasto profile) than the
widely-used NFW form;
(2) the radial profile of the pseudo-phase-space density,
continues to be well fit by a power law, as seen in earlier lowerresolution simulations.
Einasto vs NFW
Ma Chung Pei, Chang,
P., Zhang, 2009
Predict the two
properties cannot
hold at all scales
Nature of dark matter or
astrophysics process?
eg, Maschenko et al. 2006, Nature, or 2008, science, etc…
SN feedback and Radiation pressure
answer the cuspy/cored issue for spiral
galaxy
Maccio et al. ApJ 2012
-
High resolution cosmological hydro-dynamical
simulations  effects of dissipative processes
on the inner distribution of dark matter in
Milky-Way like objects (M ≈ 1012 M ⊙ ).
-
supernova feedback + effects of radiation
pressure of massive stars before explosion
 increased stellar feedback  expansion of the
DM halo instead of contraction with respect to
N-body simulations.
 Baryons erase the DM cuspy distribution
flat , cored DM density profile, well fit by a
Burkert profile, with fitting parameters
consistent with observations.
More faint or dark galaxies discovered
Eg, Belokurov et al, 2010
Missing satellites: CDM way out
• satellites do exist, but star formation suppressed (after reionization?)
• satellites orbit do not bring them to close interaction with disk, so
they will not heat up the disk.
• Local Group dwarf velocity dispersion underestimated
• Galaxies may not follow dwarves
Halo substructures may be probed by
- Lensing
- local Milky Way structures
Future Measurements of
DM properties with lensing
I. Cosmic shear power spectra: Mass constraints?
II. Galaxy-scale DM density profiles:
• Galaxy-galaxy lensing
• Magnification
Sensitivity of detection scales by lensing
Strong lensing: 1-10 kpc
Flexion:
Weak lensing:
10-100 kpc
<100 kpc
Cosmic shear power spectra
Markovic et al. 2010 Euclid-like DE space survey +Planck:
Integral effects → better than matter power spectrum
Cosmic shear power spectra
Markovic et al. 2010 Euclid-like DE space survey +Planck:
Sensitive to m_WDM < 2.5 keV
Power spectra and sensitivity to WDM
Is that interesting ? Lyman a constraints m > 2 or 4 keV or even higher –
But doubts on Lya results!
Baryon physics (AGN feedback)
affects Matter Power Spectrum
Semboloni et al. (2011)
Van Daalen et al.(2011)
Shale et al :OWLS simulation
 Consequences on WL
cosmological parameters fits
Baryon effects different from
neutrino or WDM effects
Semboloni et al. 2011
Probing DM Particle properties
CL0024
Mandelbaum et al. (2006)
Tyson, Kochanski, &
Dell’Antonio (1998)
Stacked galaxy—galaxy weak lensing
signal fit with various profiles.
Galaxy-galaxy lensing
Measure the correlation of shear of the background galaxies
with mass of the foreground galaxies
To obtain the galaxy-galaxy lensing signal, we need two
important ingredients that we can extract from the data
1)the redshift distribution of the lensed background galaxies
2)the shape of the lensed background galaxies
Surface density profile measurements
obtained from galaxy groups
in the COSMOS survey
Leauthaud et al. 2010
Magnification (Van Waerbeke et al. 2010)
An alternative way to determine the galaxy profile, especially for the
high redshift galaxies (z>=1).
- Need: precise photometry (but not shape)
- Measure: number density of galaxies
-Noise:
1. Poisson noise
2. galaxy clustering
Conclusions
• Astrophysical observations  existence of non baryonic
Dark Matter
• N-Body simulations of LSS  existence of not-hot DM?
• Many problems with CDM simulations
can be solved with
-
O(1keV) WDM
Or Baryon feedback ?
More work on N-body simulations needed !
-What can WDM be?
Sterile neutrinos?
-How can O(1keV) WDM be observed? Lensing , X-ray,…
-How can massive CDM be observed: Direct and Indirect
detection experiments + accelerator production of new
particles…
Thank You!