Dark Radiation & Superheavy Dark Matter from Black Hole - - PowerPoint PPT Presentation

Dark Radiation & Superheavy Dark Matter from Black Hole Domination

Sam McDermott Utah, Aug 7 2019

1905.01301 (with Dan Hooper and Gordan Krnjaic) (+ongoing…)

can a population of black holes that evaporate early have an observable impact on the universe?

Basic Question:

Excluded by BBN, LSS

Dark Radiation

MPl

Thermal Relic

Dark Matter

ΩΧ > ΩCDM

∼ 1 eV

∼ 1 MeV

∼ 105 GeV

The Origin of (Matter) Species

Excluded by BBN, LSS

Dark Radiation

ΩΧ > ΩCDM

Dark Matter

∼ 10 MeV

∼ 109 GeV

MPl

Hawking Radiation

Dark Radiation

MPl

Thermal Relic

Dark Matter

ΩΧ > ΩCDM

∼ 1 eV

∼ 1 MeV

∼ 105 GeV

The Origin of (Matter) Species

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

https://xkcd.com/2035/

https://xkcd.com/2035/

Black Hole Temperature

• Every black hole emits like a blackbody at a

temperature (Bekenstein 1973; Hawking 1974):

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Every black hole emits like a blackbody at a

temperature (Bekenstein 1973; Hawking 1974):

• For MBH ~ M⊙, TBH ~ 10-20 GeV

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Every black hole emits like a blackbody at a

temperature (Bekenstein 1973; Hawking 1974):

• For MBH ~ M⊙, TBH ~ 10-20 GeV
• For MBH ~ 108 gram, TBH ≫ TeV

TBH = M 2

Pl

8πMBH

Black Hole Evaporation

• Evaporation rate formula (Hawking 1974):

dMBH dt = G g?,H(TBH) M 4

Pl

30720 π M 2

BH

' 7.6 ⇥ 1024 g s−1 g?,H(TBH) ✓ g MBH ◆2

Black Hole Evaporation

• Evaporation rate formula (Hawking 1974):
• For g★,H constant with MBH, this integrates:

dMBH dt = G g?,H(TBH) M 4

Pl

30720 π M 2

BH

' 7.6 ⇥ 1024 g s−1 g?,H(TBH) ✓ g MBH ◆2

MBH(t) = Mi ✓ 1 − t τ ◆1/3

τ ≈ 0.4 s ✓ Mi 109 g ◆3✓ 108 g?,H(TBH) ◆

Evaporation Timescales

• Since τ ~ s × (Mi/109g)3:

Evaporation Timescales

• Since τ ~ s × (Mi/109g)3:
• tuniv ~ 1018 s ⟹ black holes as (component
• f) stable relic DM must have Mi ≳ 1015 g

Evaporation Timescales

• Since τ ~ s × (Mi/109g)3:
• tuniv ~ 1018 s ⟹ black holes as (component
• f) stable relic DM must have Mi ≳ 1015 g
• intermediate mass black holes constrained by

CMB (Poulin et al. 1610.10051 & JCAP; Stöcker et al. 1801.01871 & JCAP) and BBN (Kohri and Yokoyama astro-ph/9908160 & PRD; Carr et al. 0912.5297 & PRD)

Evaporation Timescales

• Since τ ~ s × (Mi/109g)3:
• tuniv ~ 1018 s ⟹ black holes as (component
• f) stable relic DM must have Mi ≳ 1015 g
• intermediate mass black holes constrained by

CMB (Poulin et al. 1610.10051 & JCAP; Stöcker et al. 1801.01871 & JCAP) and BBN (Kohri and Yokoyama astro-ph/9908160 & PRD; Carr et al. 0912.5297 & PRD)

• black holes with Mi ≲ 109 g evaporate pre-BBN

• Since τ ~ s × (Mi/109g)3:
• tuniv ~ 1018 s ⟹ black holes as (component
• f) stable relic DM must have Mi ≳ 1015 g
• intermediate mass black holes constrained by

CMB (Poulin et al. 1610.10051 & JCAP; Stöcker et al. 1801.01871 & JCAP) and BBN (Kohri and Yokoyama astro-ph/9908160 & PRD; Carr et al. 0912.5297 & PRD)

• black holes with Mi ≲ 109 g evaporate pre-BBN
• Can Mi ≲ 109 g black holes impact our universe?

Evaporation Timescales

10−10 10−7 10−4 10−1 102 105 108

T (GeV)

10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101

ρi/ρtotal

Radiation B l a c k H

• l

e s D a r k M a t t e r BBN Matter-Radiation Equality

Black Hole Energy Density

ρ(SM) rad ~ a-4, ρDM ~ a-3 no domination

10−10 10−7 10−4 10−1 102 105 108

T (GeV)

10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101

ρi/ρtotal

Radiation B l a c k H

• l

e s D a r k M a t t e r BBN Matter-Radiation Equality 10−10 10−7 10−4 10−1 102 105 108

T (GeV)

10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101

ρi/ρtotal

Radiation Black Holes D a r k M a t t e r BBN Matter-Radiation Equality

Black Hole Energy Density

ρ(SM) rad ~ a-4, ρDM ~ a-3 no domination black hole domination

• It’s possible that black holes are the dominant

source of the stuff in the universe

Black Hole Reheating

T⌧ ' 40[50] MeV ✓108 g Mi ◆3/2 ✓g?,H(TBH) 108 ◆1/2 ✓ 14 g?(T⌧) ◆1/4

• It’s possible that black holes are the dominant

source of the stuff in the universe

• Doesn’t matter for the Standard Model —

thermal equilibrium established before BBN

Black Hole Reheating

T⌧ ' 40[50] MeV ✓108 g Mi ◆3/2 ✓g?,H(TBH) 108 ◆1/2 ✓ 14 g?(T⌧) ◆1/4

• It’s possible that black holes are the dominant

source of the stuff in the universe

• Doesn’t matter for the Standard Model —

thermal equilibrium established before BBN

• Implications for dark sector?

Black Hole Reheating

T⌧ ' 40[50] MeV ✓108 g Mi ◆3/2 ✓g?,H(TBH) 108 ◆1/2 ✓ 14 g?(T⌧) ◆1/4

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

Dark Radiation, I

• Number of degrees of freedom in radiation at

CMB is conventionally parameterized by ΔNeff:

∆Neff ≡ 8 7 ✓11 4 ◆4/3 ρX(TCMB) ργ(TCMB)

Dark Radiation, I

• Number of degrees of freedom in radiation at

CMB is conventionally parameterized by ΔNeff:

• Conservation of entropy and equipartition of

energy (modulo graybody factors) gives:

∆Neff ≡ 8 7 ✓11 4 ◆4/3 ρX(TCMB) ργ(TCMB)

∆Neff ≡ 8 7 ✓11 4 ◆4/3 gH,X P

i∈SM gH,i

g∗,SM(TRH) 2 ✓gCMB

∗S

gRH

∗S

◆4/3

Dark Radiation, I

• Number of degrees of freedom in radiation at

CMB is conventionally parameterized by ΔNeff:

• Conservation of entropy and equipartition of

energy (modulo graybody factors) gives:

∆Neff ≡ 8 7 ✓11 4 ◆4/3 ρX(TCMB) ργ(TCMB)

∆Neff ≈ 0.10 ✓gDR,H 4 ◆✓ 106 g?(TRH) ◆1/3

• Number of degrees of freedom in radiation at

CMB is conventionally parameterized by ΔNeff:

• Conservation of entropy and equipartition of

energy (modulo graybody factors) gives:

∆Neff ≡ 8 7 ✓11 4 ◆4/3 ρX(TCMB) ργ(TCMB)

∆Neff ≈ 0.10 ✓gDR,H 4 ◆✓ 106 g?(TRH) ◆1/3

Dark Radiation, I

Dark Radiation, II

• How light must such a state be to be radiation?

hEDRi

• EQ

' α TBH,i ⇥ TEQ TRH ✓g?(TEQ) g?(TRH) ◆1/3 ' 3.9 MeV ✓ α 3.15 ◆✓ Mi 108 g ◆1/2✓ 108 g?,H(TBH) ◆1/2✓ 14 g?(TRH) ◆1/12

Dark Radiation, II

• How light must such a state be to be radiation?
• Slight thermal distortion ⟹ mDR ≲ 5 MeV

hEDRi

• EQ

' α TBH,i ⇥ TEQ TRH ✓g?(TEQ) g?(TRH) ◆1/3 ' 3.9 MeV ✓ α 3.15 ◆✓ Mi 108 g ◆1/2✓ 108 g?,H(TBH) ◆1/2✓ 14 g?(TRH) ◆1/12

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases
• Continues until TBH ~ MPl (at which point

Hawking’s calculation breaks down)

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases
• Continues until TBH ~ MPl (at which point

Hawking’s calculation breaks down)

TBH = M 2

Pl

8πMBH

Eventually, particles of any sub-Planck scale mass can be produced in Hawking evaporation!

10−10 10−7 10−4 10−1 102 105 108

T (GeV)

10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101

ρi/ρtotal

Radiation B l a c k H

• l

e s D a r k M a t t e r BBN Matter-Radiation Equality 10−10 10−7 10−4 10−1 102 105 108

T (GeV)

10−7 10−6 10−5 10−4 10−3 10−2 10−1 100 101

ρi/ρtotal

Radiation Black Holes D a r k M a t t e r BBN Matter-Radiation Equality

Heavy Dark Matter

Two different regimes: “freeze-in like” “freeze-out like”

(see also Morrison et al., 1812.10606) (see also Lennon et al., 1712.07664)

Heavy Dark Matter

Two different regimes:

102 103 104 105 106 107 108 109

Mi (grams)

10−14 10−12 10−10 10−8 10−6

ρBH/ρR (T = 1010 GeV)

Excluded by BBN mDM = 1017 GeV mDM = 1015 GeV mDM = 1013 GeV mDM = 1011 GeV mDM = 109 GeV

Heavy Dark Matter

Two different regimes:

102 103 104 105 106 107 108 109

Mi (grams)

10−14 10−12 10−10 10−8 10−6

ρBH/ρR (T = 1010 GeV)

Excluded by BBN mDM = 1017 GeV mDM = 1015 GeV mDM = 1013 GeV mDM = 1011 GeV mDM = 109 GeV

“freeze-in like”

Heavy Dark Matter

Two different regimes:

102 103 104 105 106 107 108 109

Mi (grams)

10−14 10−12 10−10 10−8 10−6

ρBH/ρR (T = 1010 GeV)

Excluded by BBN mDM = 1017 GeV mDM = 1015 GeV mDM = 1013 GeV mDM = 1011 GeV mDM = 109 GeV

“freeze-in like” “freeze-out like”

Heavy Dark Matter

Two different regimes:

102 103 104 105 106 107 108 109

Mi (grams)

10−14 10−12 10−10 10−8 10−6

ρBH/ρR (T = 1010 GeV)

Excluded by BBN mDM = 1017 GeV mDM = 1015 GeV mDM = 1013 GeV mDM = 1011 GeV mDM = 109 GeV

“freeze-in like” “freeze-out like” ηb can be set by initial conditions / very early universe ηb needs to be accounted for by black hole evap. as well

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases
• Continues until TBH ~ MPl (at which point

Hawking’s calculation breaks down)

TBH = M 2

Pl

8πMBH

Black Hole Temperature

• Black hole has a temperature (Bekenstein 1973; Hawking 1974):
• As MBH decreases, TBH increases
• Continues until TBH ~ MPl (at which point

Hawking’s calculation breaks down)

TBH = M 2

Pl

8πMBH

High energy particles (strongly interacting or not) can impact n/p freezeout, break up nuclei, etc.!

Results

Carr, Kohri, Sendouda, Yokoyama, 0912.5297 & PRD

ρBH/ρSM at ti

Results

Stöcker, Krämer, Lesgourgues, Poulin, 1801.01871 & JCAP

Next Steps

• Updated observations and nuclear rates

Next Steps

• Updated observations and nuclear rates
• Effects on CMB spectral distortions

Next Steps

• Updated observations and nuclear rates
• Effects on CMB spectral distortions
• Large number of extra sectors (N-naturalness)
• will change the mass / lifetime relation
• smaller fraction of energy going to SM stuff

Outline

• 1. The Mass Range of Primordial Black Holes
• 2. Dark Radiation
• 3. Superheavy Dark Matter
• 4. Effects on BBN and CMB
• 5. Concluding Comments

Some Things You Might Worry About

(Very) early universe conditions:

Some Things You Might Worry About

(Very) early universe conditions:

• formation of binaries

Some Things You Might Worry About

(Very) early universe conditions:

• formation of binaries
• gravitational wave inspiral

Some Things You Might Worry About

(Very) early universe conditions:

• formation of binaries
• gravitational wave inspiral
• accretion of SM stuff

Some Things You Might Worry About

(Very) early universe conditions:

• formation of binaries
• gravitational wave inspiral
• accretion of SM stuff
• initial mass function?

Black hole mergers

Binary capture in the early universe…

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Quinlan and Shapiro, 1989 ApJ

Binary Formation During Black Hole Domination

Binary capture in the early universe… Black hole domination:

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Quinlan and Shapiro, 1989 ApJ

Γ H ∼ ρBHMBH M 4

Pl

MPl √ρBH ∼ r ρBH M 4

Pl

MBH MPl

Binary Formation During Black Hole Domination

Binary capture in the early universe… Black hole domination:

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Quinlan and Shapiro, 1989 ApJ

Γ H ∼ ρBHMBH M 4

Pl

MPl √ρBH ∼ r ρBH M 4

Pl

MBH MPl

can be ~1

Binary Formation During Black Hole Domination

Binary capture in the early universe… Black hole domination:

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Quinlan and Shapiro, 1989 ApJ

Γ H ∼ ρBHMBH M 4

Pl

MPl √ρBH ∼ r ρBH M 4

Pl

MBH MPl

always ≫1

Binary Formation During Radiation Domination

Binary capture in the early universe…

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Γbc H ≈ 0.02 × ✓MBH 108 g ◆ ✓ Teff 107 GeV ◆2 ✓ v 10−5 ◆−11/7 ✓ρBH ρtot ◆

Quinlan and Shapiro, 1989 ApJ

Inspiral

Binary capture in the early universe… …leading to mergers?

σbc = π ✓85π 3 ◆2/7 r2

Schwv−18/7

Γbc H ≈ 0.02 × ✓MBH 108 g ◆ ✓ Teff 107 GeV ◆2 ✓ v 10−5 ◆−11/7 ✓ρBH ρtot ◆

tinsp = 5a4 512G3M 3

BH

tinsp τ ' 10 ⇥ ζ4 ✓108GeV Teff ◆8 ✓ 108g MBH ◆6

Quinlan and Shapiro, 1989 ApJ Peters, 1964 Phys Rev

Accretion

Bondi-Hoyle accretion…

dMBH dt

• Accretion

= 4πλM 2

BHρR

M 4

Pl(1 + c2 s)3/2

Bondi, 1952 MNRAS

Accretion

Bondi-Hoyle accretion… …slowing / halting the evaporation process?

dMBH dt

• Accretion

= 4πλM 2

BHρR

M 4

Pl(1 + c2 s)3/2

dMBH dt = πGg∗,H(TBH)T 2

BH

480 " λg∗(TR) Gg∗,H(TBH)(1 + c2

s)3/2

✓ TR TBH ◆4 − 1 #

Bondi, 1952 MNRAS

Future Directions

• Interesting possibility for a “nightmare-scenario”

decoupled dark sector

• Potentially observable in CMBS4
• Early-universe physics can be treated in greater

depth in UV-complete scenarios

• Possibilities for more extended hidden sectors?

Thanks!