Concentrated Dark Matter and PBHs Scott Watson ( Syracuse University - - PowerPoint PPT Presentation

Concentrated Dark Matter and PBHs

Scott Watson ( Syracuse University ) Based on:

“Concentrated Dark Matter” — PRD 97 arXiv: 1711.04773
 with J. Dror (Berkeley), E. Kuflik (Hebrew University), and B. Melcher (Syracuse) “Primordial Black Holes and Co-Decaying Dark Matter” — arXiv: 1902.04082
 with J. Georg (Rensselaer Polytech. Inst.) and B. Melcher (Syracuse)

What happens at The end of Inflation?


Gravitationally coupled hidden sectors are a 
 natural consequence of inflationary model building.

Image courtesy F . Quevedo

Plan for this talk:

Part One: Concentrated Dark Matter

Weakly coupled to Standard Model, naturally leads to departure from a radiation dominated universe Observables?

Part Two: Primordial Black Holes as Dark Matter

Weakly coupled to Standard Model. Can they be all or part of the dark matter?

Co-decay Mechanism

1/T

(time)

Dark Sector 
 decouples from SM (while relativistic) Dark Matter
 non-Relativistic Light particles Decay to SM Dark Matter
 “freezes out”

Tdec

mD

TΓ

Tf

Dark Sector is not in thermal equilibrium with Standard Model 
 (it decouples completely, very early, and while relativistic). Dark sector temperature scales differently than Standard Model. Dark Sector particles in equilibrium *with each other* until some decay. 
 No Boltzmann suppression.

“Co-Decaying Dark Matter” — PRL 117 (arXiv: 1607.03110)
 by J. Dror (Berkeley), E. Kuflik (Hebrew University), and W. Ng (Cornell)


‘A’ particles are the DM

Co-decay Mechanism (consider two particles for simplicity)

Time

Comoving
 Density

Co-decaying Dark Matter: An Explicit Model

Custodial symmetry implies nearly degenerate masses and stability of gauge bosons

O6 = ⇣ Φ†

DDµΦD

⌘ Φ†DµΦ

• Λ2

Explicitly broken to U(1)

(E.g. integrate out heavy fermions charged under both sectors)

Stable Dark Matter (“A” sector)

W ±

D =

• W 1

D ⌥ W 2 D

• /

p 2

ZD ≡ W 3

D

Decaying particle (“B” sector)

Decays to Standard model through mixing

Dark SU(2) Gauge theory with Dark Higgs

mD ' m

(D) Z

' m

(D) W

Concentrated Dark Matter

“Concentrated Dark Matter” — PRD 97 (arXiv: 1711.04773)
 with J. Dror (Berkeley), E. Kuflik (Hebrew University), and B. Melcher (Syracuse)

Co-decay leads to interesting consequences for the early cosmic history and the structure of dark matter The Dark Sector leads to an early matter dominated phase.

ρA+B ∼ a(t)ρr

B decays imply 
 A’s Boltzmann suppressed

Early Matter Domination and Structure Growth ¨ δk + 2H ˙ δk + ✓ c2

sk2 p − 3

2H2 ◆ δk = 0

Evolution of Density Perturbations

k2

J = 3H2

2c2

s Pressure prevents collapse Gravity drives collapse Hubble “friction” slows the instability Jean’s scale sets the growth scale

1405.7373 with JiJi Fan and Ogan Ozsoy 1106.0536 A. Erickcek and K Sigurdson

k ≡ ⇢(t,~ k) ¯ ⇢

Concentrated Dark Matter

Unlike, Standard SUSY WIMPs,
 Dark matter decouples from Standard Model early . Matter phase Cosmological Dark matter results from decay of hidden sector particles. Growth of substructure can lead to enhanced signals for indirect detection.

Time

Comoving
 Density

“Concentrated Dark Matter” — submitted PRL (arXiv: 1711.04773)
 with Dror, Kuflik, and Melcher

Compare to:

Fan, Ozsoy, and Watson 
 (Phy. Rev. D90)

DM very weakly interacting with the SM 


(generic expectation from UV complete models of inflation)

Early decoupling and matter phase leads to enhanced DM substructure prior to BBN


(free streaming and kinetic coupling to SM radiation are unimportant) 


If these structures survive until today, they lead to enhanced indirect detection signals.
 (work in progress…)

Concentrated Dark Matter

“Concentrated Dark Matter” — submitted PRL (arXiv: 1711.04773)
 with Dror, Kuflik, and Melcher

Plan for this talk:

Part One: Concentrated Dark Matter

Weakly coupled to Standard Model, naturally leads to departure from a radiation dominated universe Observables?

Part Two: Primordial Black Holes as Dark Matter

Weakly coupled to Standard Model. 
 Can they be all or part of the dark matter?

TeV eV

GeV

MeV

BBN CMB

Inflation Planck

Co-Decay Leads to a non-thermal history

Thermal 
 WIMPs

Liu, Slatyer, Zavala 1604.02457

Experimental:

Lack of thermal WIMP detection CMB and Inflation (Planck)
 Many inflationary models favor non-thermal history. Recombination Constraints (Planck) 
 Thermal WIMPs in tension

Theoretical:

Many String Theory models motivate non-thermal histories. 
 (Example: Moduli with low-scale masses (near TeV) form condensates.) Inflationary Reheating: 
 Transfer of energy from inflationary sector to Standard Model and hidden sectors (BSM / dark matter) can lead to prolonged matter domination. Non-Standard History —> New Phenomenology

“Cosmological Moduli and the Post-Inflationary Universe: A Critical Review ”

with Kuver Sinha and Gordon Kane [arXiv: 1502.07746]

Non-Thermal Histories Are Well Motivated

See also talk by Seyda
 ( Flavons )

Early Matter Phases

∆σ ' M ✓HI M ◆

1 n+1

Tr ' ⇣ mσ 10 TeV ⌘3/2 MeV

Γσ ∼ m3

σ

m2

p

Moduli couple gravitationally Universe reheated (again)

Matter domination from Scalar Moduli

σ → σ + c

Symmetry broken

mσ ∼ m3/2 ∼ 10 − 100 TeV

If structures can form in a matter phase, why can’t black holes?

Could primordial Black Holes be some of the dark matter?

with J. Georg JHEP 1709 (2017)

δk(tH) ∼ 10−4 − → δk(t > tH) ∼ O(1)

Non-linearity does not guarantee PBH formation!

(unlike PBH formation in a thermal universe)

( Fraction of density in black holes at Mass scale M )

Mass Fraction in PBHs (Thermal History)

δM ≡ δM M

Equation of State ( )

w > 0 Mass Fraction in PBHs (Early Matter Phase)

If structures can form in a matter phase, why can’t black holes?

Could primordial Black Holes be some of the dark matter?

with J. Georg JHEP 1709 (2017)

δk(tH) ∼ 10−4 − → δk(t > tH) ∼ O(1)

Non-linearity does not guarantee PBH formation!

(unlike PBH formation in a thermal universe)

( Fraction of density in black holes at Mass scale M )

Mass Fraction in PBHs (Thermal History)

δM ≡ δM M

Equation of State ( )

w > 0 Non-thermal History (small perturbations can grown on sub-Horizon scale)

Polnarev and Khlopov (’81), Kokubu et. al. 1810.03490, J. Georg B. Melcher, S.W. 1902.04082

PBH Mass Range from an Early Matter Phase

Low Mass Region

Matter phase begins at Hosc ' mσ No sub-horizon growth yet, only possibility is collapse of entire Hubble patch into a PBH.

Mmin = 3 m2

p

mσ

3H2

• scm2

p = ρP BH = MP BHH−3

• sc

Overly conservative!

PBH Mass Range from an Early Matter Phase

High Mass Region

Sub-horizon growth is important.

δM(tr) = δcmb ✓Mmax Mcmb ◆ 1−n

6

✓ tr tH ◆2/3 ' O(1)

Normalize to CMB scales Tilt of Primordial spectrum Sub-horizon growth

Solve this equation implicitly for mass

Mmax ∼ ✓Mcmb mp ◆ n−1

n+3 ✓ mp

mσ ◆

12 n+3

mp

T 2

r ∼ m3 σ

mp

Duration of matter phase determines maximal mass

PBH Mass Range from an Early Matter Phase

Mmax ∼ ✓Mcmb mp ◆ n−1

n+3 ✓ mp

mσ ◆

12 n+3

mp

T 2

r ∼ m3 σ

mp

Duration of matter phase determines maximal mass

Mmin = 3 m2

p

mσ

Mass range depends on two parameters.

mσ n

Tilt of primordial power spectrum Moduli mass

PBH Mass Range from an Early Matter Phase

Mmax ∼ ✓Mcmb mp ◆ n−1

n+3 ✓ mp

mσ ◆

12 n+3

mp

T 2

r ∼ m3 σ

mp

Duration of matter phase determines maximal mass

Mmin = 3 m2

p

mσ

Mass range depends on two parameters.

mσ n

Tilt of primordial power spectrum Moduli mass

Key point #1

Not a free parameter:
 Connected to underlying theory (We were trying to restrict theory)

mσ ∼ m3/2 ∼ 10 − 100 TeV

PBH Mass Range from an Early Matter Phase

Mass range depends on one parameter.

n

Tilt of primordial power spectrum

Key point #1

Not a free parameter:


Connected to underlying theory (We were trying to restrict theory)

mσ ∼ m3/2 ∼ 10 − 100 TeV

Key point #2

Entropy production from scalar decay will dilute PBHs (Last PBHs to form are least diluted)

Mmax ∼ ✓Mcmb mp ◆ n−1

n+3 ✓ mp

mσ ◆

12 n+3

mp

Lighter PBHs will still form (although diluted) and we 
 can use observations to restrict the spectral index

n

Tilt of primordial power spectrum

Key point #3

0912.5297 Carr, et. al.

Strongest constraints come from evaporating PBHs

Planck Constraint on Relic PHBs

with Steven Clark, Bhaskar Dutta, Yu Gao, and Louis Strigari (arXiv:1612.07738)

PBH Dark Matter from Moduli Decay

n . 1.6 Mpbh ' 30 M mσ ' 50 TeV

Can this be all of the dark matter?

Did LIGO see PBH Dark Matter?

Dark Matter Interpretation

LIGO detected a gravity wave signal consistent with the merger of two Black holes at around a 1.3 billion Lyr away

∼ 30 M

Lensing
 (improved) Disrupt Wide Binaries
 (perhaps CMB as well)

Constraints weaken if PBHs are not all of the dark matter. 1603.08338 Sasaki, et. al.;

“GW150914”

LIGO observation lies in the window where 
 MACHOs are still viable to be all of the dark matter.

20 M . M . 100 M

defense

Bird, et. al. PRL 116 [arXiv: 1603.00464]

See talk by Stefano

Relic Density in PBH Dark Matter

Allowing for uncertainties in formation process Optimistically

log (Ωpbh)

Ωpbh ' 10−6

Relic Density in PBH Dark Matter

Uncertainties in formation process Optimistically

log (Ωpbh)

Ωpbh ' 10−6

Range of PBH masses (duration of matter domination) is too wide in the expected models. Unique feature: Matter phase gives range of masses.

PBHs from Co-Decay

Matter phase much shorter lived 
 (e.g. constraints on SU(2) model imply)

PBHs from Co-Decay

Matter phase much shorter lived

ψ(M) = aeq adecay ✓βdecay M ◆

fPBH ≡ ΩPBH ΩDM = Z Mmax

Mmin

ψ(M) dM

Minimal mass ~ Horizon size at start Maximal mass

Data set courtesy of B. V. Lehmann, 


• S. Profumo, and J. Yant

Allowed fraction of DM in PBHs Produced from Co-Decay

“Primordial Blackholes and Co-decaying Dark matter” 
 with J. Georg (RPI) and B. Melcher (Syracuse) — arXiv: 1902.04082
 (dashed lines are 10 times 
 the decay rate)

See talk by Stefano

log ✓fPBH fA ◆

m2

DM

ΓB

Relative fraction of DM to PBHs

“Primordial Blackholes and Co-decaying Dark matter” 
 with J. Georg (RPI) and B. Melcher (Syracuse) — arXiv: 1902.04082


Here we fix DM mass to be 100 GeV

Ruled out

Conclusions

Co-Decay leads to a novel way to populate dark matter. Dark matter decouples from the Standard Model early, and collider and direct detection is hopeless. The matter phase leads to Concentrated Dark Matter mini-halos and possible boosted signals for indirect detection. The matter phase may also explain the abundance of near solar mass black holes seen by LIGO — which could also be part of the DM.