Beyond CDM: New DM candidates and structure formation Cline Boehm - - PowerPoint PPT Presentation

Beyond CDM: ‘New’ DM candidates and structure formation

Céline Boehm

IPPP, Durham LAPTH, Annecy

Oslo, 16th January 2015

LCDM forever? Are we stuck?

Planck 2013

Tegmark et al 2002

The `magic’ properties of WIMPs

You don’t need to know the DM particle mass nor cross section (i.e. their particle properties) to make predictions So far observations are consistent with WIMPs effects are expected at very small scales (but as V. Mukhanov said…beliefs are not enough!)

too heavy to free-stream significantly too weakly interacting to damp fluctuations

˙ θb = k2ψ−H θb +c2

sk2δb −R−1 ˙

κ(θb −θγ) ˙ θγ = k2ψ+k2 1 4δγ −σγ ⇥ − ˙ κ(θγ −θb) , ˙ θDM = k2ψ−H θDM ,

˙ θb = k2ψ−H θb +c ˙ θγ = k2ψ+k2 1 4δ −˙ κ(θγ −θb)− ˙ θDM = k2ψ−H θDM

Damping Collisional Damping Free-streaming

Exploring the parameter space in a systematic way guiding principle?

;::2:31:D:

T(k) = ⇥ 1 + (αk)2µ⇤−5/µ

a

;::2:31:D:

rin

α = 0.048 hmDM keV i−1.15 ΩDM 0.4 0.15  h 0.65 1.3 Mpc h

Free-streaming (damping) scale

No interaction, tdec = “0”time;

lstruct ∼ 100 kpc ⇣mDM keV ⌘−4/3

HDM This calculation only depends on the moment where DM becomes non relativistic so it only depends on the DM mass

lfs = Z t0

tdec

v(t) a(t) dt

Z tnr

tdec

dt... + Z t0

tnr

dt...

(astro-ph/0012504, astro-ph/0410591)

+ Primordial fluctuations can be used as a tracer

very ! small !clumps ! in !the !primordial ! Universe no !very ! ! small !clump ! in !the !primordial ! Universe

+

WDM

http://arxiv.org/abs/1404.7012

see M. Viel

1306.2314 and many others

WDM candidates

keV sterile neutrinos gravitinos

+ 3.5 keV line

1306.4954

−4 −2 2 log10(k/h Mpc−1) −12 −10 −8 −6 −4 −2 2 log10(k3P(k))

Cold Warm M2L25

1412.4391 0812.0010

gravitinos as NLSP can explain a reduction of power at dwarf scales and be compatible with LHC&BBN/CMB constraints

Sterile neutrino, gravitino all have extremely weak interactions Quid a realistic situation?

lfs = Z t0

tdec

v(t) a(t) dt

depend on interactions depend on mass depend on the history of the Universe

Z tnr

tdec

c a(t)dt + Z t0

tnr

v(t) a(t)dt if tdec < tnr

Z tnr

tdec

v(t) a(t)dt if tdec < tnr

3 parameters

tdec, tnr, teq

Γ, mDM, teq

interaction !rate

Classification

1/Γdec = teq tnr = teq

3 parameters

tdec, tnr, teq

Γ, mDM, teq

Γ mDM

Z tnr

tdec

c a(t)dt + Z t0

tnr

v(t) a(t)dt if tdec < tnr

(astro-ph/0012504, astro-ph/0410591)

RegionI RegionII RegionIII

Z tnr

tdec

v(t) a(t)dt if tdec < tnr to

Free-streaming & Self-damping only

MeV

neutrino-like WIMPS self-interactions strong interactions

lfs ∝ m−4/3

DM

(astro-ph/0012504, astro-ph/0410591)

keV masses

“Real” Physics

lfs = Z t0

tdec

v a(t) × dt

Both effects together! Collisional damping free-streaming A32 !(

:B2ABAA3;312:: l2

id ∼ 2 π2

3 Z tdec(dm−i) ρi v2

i

ρt a2 Γi dt

• nce one adds interactions

But collisional damping first.

(astro-ph/0012504, astro-ph/0410591)

Collisional damping

˙ θb = k2ψ−H θb +c2

sk2δb −R−1 ˙

κ(θb −θγ) ˙ θγ = k2ψ+k2 1 4δγ −σγ ⇥ − ˙ κ(θγ −θb) , ˙ θDM = k2ψ−H θDM ,

˙ θb = k2ψ−H θb +c2

sk2δb −R−1 ˙

κ(θb −θγ) ˙ θγ = k2ψ+k2 1 4δγ −σγ ⇥ −˙ κ(θγ −θb)− ˙ µ(θγ −θDM) , ˙ θDM = k2ψ−H θDM −S−1˙ µ(θDM −θγ) .

Translation in terms of Cosmological perturbations

without DM interactions with DM interactions

+

no !very ! ! small !clump ! in !the !primordial ! Universe

+

Implications for the Universe and Milky Way

10-10 10-8 10-6 10-4 10-2 100 102 1 10 100 P(k) [(h-1 Mpc)3] k [h Mpc-1] CDM’ WDM CDM CDM

One can exclude some values of the elastic scattering cross sections In agreement with present observations, effects are just at the limit of our ability to test the matter power spectrum

works also with neutrinos possible model building and connection with neutrino masses

hep-ph/0612228

Self-interactions

sDAO mD = 1 GeV aD = 0.008 BD = 1 keV x0 = 0.5

10-4 0.001 0.01 0.1 1 10 100 10-12 10-9 10-6 0.001 1 1000

k @hêMpcD PHkL @HMpcêhL3D

Cold DM Silk Damping Envelope Warm DM Analogue Self-Interacting DM wDAO mD = 1 TeV aD = 0.009 BD = 1 keV x0 = 0.5

10-4 0.001 0.01 0.1 1 10 100 10-14 10-10 10-6 0.01 100

k @hêMpcD PHkL @HMpcêhL3D

Cold DM Silk Damping Envelope Warm DM Analogue Self-Interacting DM

• FIG. 1: Comparison between the linear matter power spectra as a function of wavenumber k for SIDM with a light mediator

(here, dark atoms) and that of WDM with a free-streaming length comparable to the sound horizon of the former. We also display the standard matter power spectrum for cold collisionless dark matter as well as a fit to the Silk damping envelope of

• SIDM. The left panel displays the benchmark model for which rDAO rSD (strong DAO), while the right panel shows the

scenario for which rDAO ⇠ rSD (weak DAO). Here, ξ0 ⌘ ξ(TCMB,0).

1405.2075

arXiv:1412.1477

core/cusp problem solved naturally… The initial to introduce this …

self-interactions

• 2.5
• 2
• 1.5
• 1
• 0.5

0.5 1 1.5 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 log10 dn/dlnM [h3 Mpc-3] log10 Mvir [h-1 M⊙]

Mhm

CDM WDM νCDM γCDM ST (r top-hat) ST (k top-hat) ST (r top-hat) + Schneider correction

interactions with radiation

http://arxiv.org/pdf/1405.2075.pdf http://arxiv.org/pdf/1412.4905.pdf

100 101 102 103 104 500 1000 1500 2000 2500 3000 3500 4000 4500 [l(l+1) Cl

TT / 2] (µK2)

l u = 10-4 WMAP-9 Planck SPT ACT

20 40 2750 3000 3250

http://arxiv.org/pdf/1309.7588.pdf

Deviations may show at very small scale for CMB LSS constraints favour no observable deviation.

BUT CMB DOES CONSTRAIN THE COSMO PARAMETERS!

Should we see deviations in the CMB?

Ultra light axions

10

−2

10

−1

10

4

k[hMpc

−1]

P (k)[(h−1Mpc )3] SDSS ACT

1110.0502

• FIG. 2:

The matter power spectrum for three cosmolo- gies shown with current measurements from SDSS [96], and ACT [63]. We show first the WMAP7 cosmology (dashed black line). We also show two axion cosmologies, both with ma = 10−29 eV: fax = 0.1 (solid blue line), and fax = 0.01 (solid black line), with all other parameters held fixed at their WMAP7 values. Both axion cosmologies have only a small effect on the CMB power spectrum, but are clearly distin- guished in their effect on P(k), with fax = 0.1 clearly ruled

• ut by the data.

10

1

10

2

10

3

10

3

ℓ ΛCDM fax = 0.1, ma = 10−30eV fax = 0.1, ma = 10−31eV fax = 0.01, ma = 10−29eV fax = 0.01, ma = 10−31eV

1110.0502

(see Pedro Ferreira)

Decaying DM

Figure 2. Small-scale structure in a Milky Way mass halo (Z12) in CDM (left) and DDM models with Γ−1 = 40 Gyr and Vk = 100 km/s (middle) and Γ−1 = 10 Gyr and Vk = 20 km/s (right) within 260 kpc of the halo centers at z = 0. The color scheme indicates the line-of-sight projected square of the density in

• rder to emphasize the dense structures such as the host halo interiors and the associated subhalos. The DDM halos have slightly more diffuse central regions.

The abundance and structure of subhalos are altered significantly compared to CDM in both of the DDM simulations presented.

Late or primordial times effect

1406.0527

But if decay too fast, this becomes problematic you would see electromagnetic emission (unless you introduce 2 types of DM particles)

Is DM a particle?

no DM particle found so far. Maybe DM is just a modification of gravity TeVeS not as good as DM It will get even worse! How to reproduce the 7-8 peaks seen by Planck & ACT/SPT(pol)?

Probably!

astro-ph/0505519 1307.5458.pdf

Very heavy DM

needs DM particles interacting ~100 times stronger than expected Too small cross section to be seen in LSS pure CDM and no signal to be seen in experiments (LHC???) life expectancy of heavy WIMP: forever (theory) / lost interest in ~5-10 years (unless breakthrough)

No WIMPs, no more LCDM …(???)

cross section smaller than neutrinos at MeV Cosmologists !(e.g. !structure !formation&CMB) !assume !WIMPs !exist !to !make !their !predictions ! Particle !physicists !think !WIMPs !will !be !seen !at !LHC

But is DM made of WIMPs?

1 10 100 1000 104 10 50 10 49 10 48 10 47 10 46 10 45 10 44 10 43 10 42 10 41 10 40 10 39 10 38 10 37 WIMP Mass GeV c2 WIMP nucleon cross section cm2

CDMS II Ge (2009) X e n

• n

1 ( 2 1 2 )

C R E S S T CoGeNT (2012) CDMS Si (2013)

EDELWEISS (2011)

DAMA

SIMPLE (2012) ZEPLIN-III (2012) COUPP (2012) L U X ( 2 1 3 ) D A M I C ( 2 1 2 ) C D M S l i t e ( 2 1 3 ) 1 N e u t r i n

• E

v e n t s 1 N e u t r i n

• E

v e n t s 1 N e u t r i n

• E

v e n t 3 N e u t r i n

• E

v e n t s 3 N e u t r i n

• E

v e n t s 3 N e u t r i n

• E

v e n t s 1 N e u t r i n

• E

v e n t 3 N e u t r i n

• E

v e n t s 1 N e u t r i n

• E

v e n t s 1 N e u t r i n

• E

v e n t s

1307.5458.pdf

Conclusion

normal/heavy WIMPs: Lighter WIMPs: about to be excluded or to become invisible not so many chances to be found no LSS effect LSS effects soon observable But, theoretically, much harder and much more constrained

Beyond (L)CDM candidates should show up in the non linear regime (true for MG and DM!) agree with Beth Reid’s talk

Elastic scattering cross section Annihilation cross section

σ ∼ 10−36 ⇣mDM MeV ⌘ cm2

σv ∼ 10−26 ⇣mDM MeV ⌘ cm3/s

N

ɸ ɸ

Dirac Majorana Complex Real Equil.with ⇤ Equil.with ⇥⇤e

0.1 1 10 50 1 2 3 4 5 6

m MeV⇥ Neff

• C. Boehm, M. Dolan, C. McCabe arXiv:1303.6270,

based on Serpico&Raffelt 2005

v v

N

ɸ ɸ

v v

Impact on neutrino physics

N N

ɸ ɸ ɸ ɸ

v v v v

With MeV DM (mN=mDM) one obtains

Effective theory

(N singlet of SU(2) for example)

σDM−ν ' 1.2 10−36 ⇣ mN MeV ⌘2 ✓ hσvi 3 10−26 cm3/s ◆ ⇣ mDM MeV ⌘−2 cm2 C.Boehm, Y . Farzan, S. Palomares-Ruiz, T Hambye, S. Pascoli hep-ph/0612228

H0 changes as this enables to change the horizon

Compatibility with Planck

Neff is important! Planck

P(k) + Lyman alpha

But maybe DM particles are just a fake concept?

no DM particle found so far. Maybe DM is just a modification of gravity TeVeS not as good as DM It will get even worse! How to reproduce the 7-8 peaks seen by Planck & ACT/SPT(pol)?

Probably not!