Dark matter in cosmology
Theory Center, KEK and SOKENDAI, Tsukuba
Kazunori Kohri 郡 和範
16/11/08 Kaz Kohri (KEK)
Introduc)on
16/11/08 Kaz Kohri (KEK)
Planck Satellite
Einstein’s Cosmological Constant
Or unknown scalar field?
Visible Matter
Invisible Matter
Not Even Matter
Friedmann equa)on
• Hubble parameter
• Density parameter
• Cri)cal energy density
• Flat universe (K=0)
H(t ) = !a /a
H 2 = 8πG
3ρ - K
a2
Ω
j(t ) = ρ
j(t ) / ρ
cr(t )
ρcr(t ) = 3H(t)2 / (8πG)
ρ =ρΛ +ρ
CDM +ρ
b +ρ
R
ρm
=ρCDM
+ρb
−ΩK(t ) ≡ K / (aH)2 = Ω
Λ(t ) +Ω
m(t ) +Ω
R(t ) − 1 = 0
ΩΛ(t
0) +Ω
m(t
0) = 1
a(t): scale factor
Cosmic time (or the scale of the Universe)
Ener
gy d
ensi
ty
Cosmic temperature↓
13.7Gyr 105yr
Dark energy
(Cosmological constant, Quintessence)
Matter-radiation equality (EQ)
Higgs energy scale
テキスト
!10−56 !times!smaller!than!the!Higgs!pot.!energy!scale
!10−10 !sec
!1056 !times!larger!than!the!DE!scale
!1015 !K!(1015 !F)
30% ρm∝a −3
0.01% ρr∝a −4
70% ρΛ
~ const.
Ωm ΩΛ
http://map.gsfc.nasa.gov/
Exponentially “accelerated”
expansion
(2nd Inflation?)
Contraction
Fine-tuned decelerated expansion
DARK MATTER • We cannot observe them • We do not know who they are
New supersymmetric particle (neutralino χ)
axion
Primordial black holes
16/11/08 Kaz Kohri (KEK)
Sterile neutrino
Properties of DM
• Completely obscured optically
• Gravitated toward the galaxy/clustes of galaxies
• 5 times more abundant than baryon (atoms)
• Decelerating the cosmic expansion
16/11/08 Kaz Kohri (KEK)
Clear Evidences?
16/11/08 Kaz Kohri (KEK)
Observing Doppler shift of 21 cm line of neutral hydrogen
1) Rotation curves of spiral galaxies
halo r
velocity
acceleration
Disk
a = v 2
r~ G M
r2
v ~ GM / r ?
Rotating planets in solar systemless dark-‐‑‒matter system
16/11/08 Kaz Kohri (KEK)
v ~ GM / r
Rota)on curve
二間瀬敏史著 「なっとくする宇宙論」
Begeman, Broils,Sandars etal (91)
Dark Halo
gas
Stars (visible component)
velo
city
v ~constant
2) Gravita)onal Lensing Effects
二間瀬敏史著 「なっとくする宇宙論」
Gravita)onal lensing in colliding cluster of galaxies
• Red: Baryon observed by X-‐ray produced by brems of thermal electron
• Blue: DM observed by gravita)onal lens
(2007)
σm
< ) ~ (2
Baryon σ/m ~ 4b/GeV is excluded
Bullet Cluster
Gravita)onal Lens Effect • Cosmos Evolu)on Survey (コスモスプロジェクト) • 2 square degree, 500 thousand galaxies, 0.05 arcsec
1 Gpc Richard Massey et al (07) http://cosmos.phys.sci.ehime-u.ac.jp/~tani/Cosmos/PressRelease/
3) Structure forma)on
• Only pure fluctua)on of baryon is too small to produce LSS because of oscilla)on and Silk damping
• CDM fluctua)on evolves aWer maXer-‐radia)on equality epoch, which is ahead of baryon fluctua)on
• Baryon fluctua)on catches up with CDM fluctua)on aWer recombina)on
Cold Dark Matter (CDM) has an essential role for formation of Large Scale Structure (LSS), i.e, galaxies and clusters of galaxies
δ ∝ a(t )
16/11/08 Kaz Kohri (KEK)
Time-evolution of CDM fluctuation
Ma and Bertschinger (95)
-6 -5 -4 -3 -2 -1
Log a
Horizon reentry before matter-radiation equality epoch
∝a aEQ
CDM Baryon
photon
∝log(a)
CDM
Baryon
photon
∼ ∼
16/11/08 Kaz Kohri (KEK)
arec
Log a
Then a galaxy (made by baryons) is produced inside the CDM halo due to the gravity of dark matter
First, dark matter halo was produced in the early universe
Time-‐evolu)on of the DM fluctua)on to produce a galaxy
ρDM
ρbaryon
~ 5
16/11/08 Kaz Kohri (KEK)
Baryon Acous)c Oscilla)on (BAO)
16/11/08 Kaz Kohri (KEK)
Matter power spectrum in k-space
http://www.aip.de/groups/cosmology/
2-point corr. func. in real space
Bassett and Hlozek, arXiv:0910.5224 [astro-ph.CO]
CMB observa)ons
16/11/08 Kaz Kohri (KEK)
Temperature fluctua)on
16/11/08 Kaz Kohri (KEK)
Planck 2015 results. XIII, 1502.01589v3
Is the universe open or flat?
16/11/08 Kaz Kohri (KEK)
https://map.gsfc.nasa.gov/mission/sgoals_parameters_geom.html
ΩK= 0
ΩK> 0
Flat with cosmological constant ΩK ~ 0
16/11/08 Kaz Kohri (KEK)
http://background.uchicago.edu/~whu/animbut/anim3.html
ΩK= 1 − Ω
m− Ω
Λ~ 0
ΩΛ= 1 − Ω
m
Ω
CDM+Ω
baryon+Ω
Λ= 1 − Ω
K= 1
Wayne Hu’s HP
Open universe ΩK > 0
16/11/08 Kaz Kohri (KEK)
http://background.uchicago.edu/~whu/animbut/anim3.html
ΩK= 1 − Ω
m− Ω
Λ~ 0.7
ΩΛ= 1 − Ω
m~ 0.7
Wayne Hu’s HP
Flat with cosmological constant
16/11/08 Kaz Kohri (KEK)
http://background.uchicago.edu/~whu/animbut/anim3.html
ΩCDM~ 0.25, e.g., Ω
CDMh2 ~ 0.12 ΩCDM
+Ωb+Ω
Λ= 1
Ωm= Ω
CDM+Ω
b~ 0.3
Wayne Hu’s HP
Flat, but 100% dark maXer
16/11/08 Kaz Kohri (KEK)
http://background.uchicago.edu/~whu/animbut/anim3.html
ΩCDM~ 1, e.g., Ω
CDMh2 ~ 0.5
ΩCDM+Ω
b+Ω
Λ= 1
Ωm= Ω
CDM+Ω
b
Wayne Hu’s HP
Combined Figure
Lahav-Liddle PDG (2009) Planck 2015 results. XIII, 1502.01589v3
galaxies (BAO etc)
+ Lensing potential reconstruction + Baryon Acoustic Oscillation (BA0)
Candidates for dark maXer • Weekly Interac)ng Massive Par)cle (WIMP)
[Lightest SUSY Par)cle (LSP) neutralino χ, right-‐handed sneutrino , …]
• Axion
• Right-‐handed (sterile) neutrino
• SuperWIMP [gravi)no ψμ, axino , …] • Primordial black hole (PBH) • …
νR
νR(ν
s)
16/11/08 Kaz Kohri (KEK)
!a
a
Weakly-‐interac)ng massive par)cle (WIMP)
• Value of the annihila)on cross sec)on is close to the Weak one
• Relic density coincides the observed value (WIMP miracle) if <σv>~3 ×10-‐26 cm3/sec
• Supersymmetric partners can be the dark maXer
neutralino ⇔ photon, Z-boson, Higgs
right-handed scalar neutino ⇔ Right-handed neutrino 16/11/08 Kaz Kohri (KEK)
Thermal freeze out of WIMP
σv = 3× 10−26cm3 / s
16/11/08 Kaz Kohri (KEK)
Boltzmann equation
nχ ∼
3Hσ v
frezeout
Ωχ ∼ 0.25σ v
0.1TeV( )2
⎛
⎝
⎜⎜⎜
⎞
⎠
⎟⎟⎟
−1 TFreezeout mχ / 23
Ωχ h2 does not depend on mχ Predicting TeV Physics!!!
∝Exp[-m/T]
ρDM
s= m
DM
nDM
s
x
F= m
TF
∼ 20 − 30
Indirect detec)on of DM Annihilation or Decay?
Daughter particles Propagations of charged particles
16/11/08 Kaz Kohri (KEK)
Gamma-‐ray by Fermi
Constraints from Dwarf steroidals by Fermi collaboration 16/11/08 Kaz Kohri (KEK)
Cosmological bounds on annihila)ng dark maXer
Planck 2015 results. XIII. Cosmological parameters
For electromagnetic modes from CMB In order not to delay recombination
For b-bbar modes from BBN In order not to produce more D
Kawasaki, Kohri, Moroi (2015) 16/11/08 Kaz Kohri (KEK)
Galac)c-‐center gamma-‐ray excesses and dark maXer annihila)on
16/11/08 Kaz Kohri (KEK)
Daylan et al, 2014
Constraints by Fermi gamma-‐ray saXelite
16/11/08 Kaz Kohri (KEK)
Fermi-LAT Collaboration (Ackermann, M. et al.) Phys.Rev.Lett. 115 (2015)
Primordial Black Hole dark maXer
16/11/08 Kaz Kohri (KEK)
Carr, Kohri, Sendouda, Yokoyama (2009)
Horizon mass with the density fluctuation of the order O(1) can collapse to a PBH
Mas
s fr
acti
on a
t th
e fo
rmat
ion
Frac
tion
to
dark
mat
ter
dens
ity
Carr, Kunel, Sandstad (2016)
PBH cannot become 100% DM?
Positron and an)proton by AMS-‐02 or future CALET
Kohri et al, in preparation
But still large uncertainties in the propagation models 16/11/08 Kaz Kohri (KEK)
An)proton excesses and annihila)ng dark maXer
16/11/08 Kaz Kohri (KEK)
Qui et al, arXiv:1610.03840 [astro-ph.HE] Cuocco et al, arXiv: 1610.03071v1
keV sterile neutrino DM
16/11/08 Kaz Kohri (KEK)
Berlin and Hooper, 2016 Klasen, Michael et al. arXiv:1507.03800 [hep-ph]
Ω
νs~ 0.3 (m
νs/ keV)
Relic abundance decoupled before the QCD phase transition (Tdec >> 100 MeV)
Oscillation produces larger amount of DM
PeV neutrinos by IceCube
IceCube collaboration M. G. Aartsen et al, 2015 IceCube collaboration
M. G. Aartsen et al, 2014 16/11/08 Kaz Kohri (KEK)
Lower bounds on life)me for decaying DM
Rott, Kohri, Park ,2015
To be consistent with the flux, but statistically insufficient to obtain an upper bound
16/11/08 Kaz Kohri (KEK)
Summary
• (Cold) dark maXer (CDM) exists in the Universe with the energy frac)on of 27%, or 5 )mes larger than baryon (atoms)
• There are many candidates of CDM such as WIMP, axion, PBH, sterile neutrino, …
• Our next step is to detect it with high confidence levels and reveal its nature
16/11/08 Kaz Kohri (KEK)
To answer Sergey Petcov‘s ques)on
16/11/08 Kaz Kohri (KEK)
Future constraints on neutrino hierarchy by 21cm, CMB and BAO
• Hierarchy parameter Oyama, Kohri, Hazumi (2015)
rν≡
m3−m
1
Σmi
=> 0 normal hierarchy< 0 inverted hierarchy
⎧⎨⎪
⎩⎪
Future constraints on neutrino mass by 21cm, CMB, and BAO
Oyama, Kohri, Hazumi (2015)
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