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Bounds on evolution histories of the early Universe from indirect dark matter searches Riccardo Catena Istitut fr Theoretische Physik (ITP), Heidelberg 22.07.10 R. C., N. Fornengo, M. Pato, L. Pieri and A. Masiero, Phys. Rev. D 81 (2010) M.

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SLIDE 1

Bounds on evolution histories of the early Universe from indirect dark matter searches Riccardo Catena

Istitut für Theoretische Physik (ITP), Heidelberg

22.07.10

  • R. C., N. Fornengo, M. Pato, L. Pieri and A. Masiero, Phys. Rev. D 81 (2010)
  • M. Schelke, R. C., N. Fornengo, A. Masiero and M. Pietroni, Phys. Rev. D 74 (2006)
  • R. C., N. Fornengo, A. Masiero, M. Pietroni and F. Rosati, Phys. Rev. D 70 (2004)

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 1 / 17

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SLIDE 2

Overview

  • Can the early Universe expand faster than in General Relativity?
  • If yes, thermal dark matter has larger annihilation cross section:

ΩDMh2 ∝ Hf σannvf = ⇒ “Cosmological boost factor”

  • In Scalar-Tensor theories it is possibile to realize H/HGR >> 1

. C., N. Fornengo, A. Masiero, M. Pietroni and F. Rosati, Phys. Rev. D 70 (2004)

  • 17.5
  • 15
  • 12.5
  • 10
  • 7.5
  • 5
  • 2.5

log10 T

  • T0

1 10 100 1000

HJF

2

  • HGR

2

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 2 / 17

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SLIDE 3

Overview: theories with H = HGR H2

GR =

1 3M2

p

ρtot ≃ 2.76 g∗ T 4 M2

p

1

Change the number of relativistic d.o.f.’s, g∗ ;

2

Consider a ρtot not dominated by relativistic d.o.f.’s;

  • Kination

P . Salati, Phys. Lett. B 571 (2003) 121 3 Consider theories where the effective Planck mass is different from the

constant Mp:

  • Scalar-Tensor theories
  • R. C., N. Fornengo, A. Masiero, M. Pietroni and F. Rosati, Phys. Rev. D 70 (2004) 063519
  • Extradimensions
  • L. Randall and R. Sundrum, Phys. Rev. Lett. 83 (1999) 4690
  • . . .

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 3 / 17

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SLIDE 4

Overview

  • Can we set an upper bound for such cosmological boosts? Yes
  • Main assumption: Thermal dark matter production
  • Method: The Boltzmann equation

˙ n + 3Hn = −σannv(n2 − n2

eq)

ΩDMh2 ∝ Hf σannvf ΩDMh2 = ⇒ from WMAP σannvf = ⇒ bounds from indirect dark matter detection 9 > > = > > ; = ⇒ Constraints on Hf

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 4 / 17

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SLIDE 5

Outline

1

The dark matter decoupling

2

Bounds on σannvf from indirect dark matter searches

3

Bounds on the Hubble expansion

4

Conclusions

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 5 / 17

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SLIDE 6

Outline

1

The dark matter decoupling

2

Bounds on σannvf from indirect dark matter searches

3

Bounds on the Hubble expansion

4

Conclusions

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 5 / 17

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SLIDE 7

Outline

1

The dark matter decoupling

2

Bounds on σannvf from indirect dark matter searches

3

Bounds on the Hubble expansion

4

Conclusions

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 5 / 17

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SLIDE 8

Outline

1

The dark matter decoupling

2

Bounds on σannvf from indirect dark matter searches

3

Bounds on the Hubble expansion

4

Conclusions

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 5 / 17

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SLIDE 9

The dark matter decoupling

  • The Boltzmann equation:

˙ n + 3Hn = −σannv(n2 − n2

eq)

  • Two rates:

1) Hubble rate H 2) Annihilation rate Γ = nσannv

  • When H/Γ > 1 =

⇒ dark matter decoupling

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 6 / 17

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SLIDE 10

The dark matter decoupling: a window on the early Universe

  • From the Boltzmann equation:

ΩDMh2 ∝ Hf σannvf

  • The ratio Hf/σannvf is fixed by CMB observations

= ⇒ A bound on σannvf can constrain Hf

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 7 / 17

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SLIDE 11

Bounds on σannv from indirect dark matter searches: data Charged particles:

  • Antiprotons (PAMELA)
  • Positron fraction (PAMELA)
  • Electron+positron flux (FERMI,HESS)

γ-rays:

  • Diffuse emission (Fermi,EGRET)
  • From the galactic center (HESS)

Radio photons:

  • Radio observations from the galactic center

R.D.Davies, D.Walsh, R.S.Booth, MNRAS 177, 319-333 (1976)

Optical depth of CMB photons (WMAP)

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 8 / 17

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SLIDE 12

Bounds on σannv from indirect dark matter searches: assumptions

  • s-wave annihiations
  • Dark matter profile:

1) Via Lactea II simulation 2) Aquarius simulation 3) Cored profile with ρlocal ≃ 0.4 GeV cm−3

  • R. Catena and P

. Ullio, arXiv:0907.0018 [astro-ph.CO]. To be published in JCAP

  • Diffusion model:
  • F. Donato, N. Fornengo, D. Maurin and P

. Salati, Phys. Rev. D 69 (2004) 063501

  • J. Lavalle, Q. Yuan, D. Maurin and X. J. Bi, arXiv:0709.3634 [astro-ph]
  • Annihilation channels:

DM+DM → e+ + e−, τ + + τ −, µ+ + µ−, W + + W −, b + ¯ b

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 9 / 17

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SLIDE 13

Bounds on σannv from indirect dark matter searches: DM+DM → e+ + e−

VL2

DMDMee

MED propagation

Γe3.3

Γ from GC

  • ptical depth

radio band ICS

EGRET 5x30 EGRET 10x60 EGRET 1020 FERMI 1020

e e e e e e bestfit unitarity bound ee 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 10 / 17

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SLIDE 14

Bounds on σannv from indirect dark matter searches: DM+DM → e+ + e−

VL2 DMDMee

MED propagation Γe3.3 Γ from GC

  • ptical depth

radio band ICS EGRET 5x30 EGRET 10x60 EGRET 1020 FERMI 1020 e e e e e e bestfit unitarity bound ee 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

AQU DMDMee

MED propagation Γe3.3 Γ from GC

  • ptical depth

radio band ICS EGRET 5x30 EGRET 10x60 EGRET 1020 FERMI 1020 e e e e e e bestfit unitarity bound ee 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

ISO DMDMee

MED propagation Γe3.3 Γ from GC

  • ptical depth

radio band ICS EGRET 5x30 EGRET 10x60 EGRET 1020 FERMI 1020 e e e e e e bestfit unitarity bound ee 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 11 / 17

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SLIDE 15

Bounds on σannv from indirect dark matter searches: DM+DM → W + + W −

VL2

DMDMWW

MED propagation

Γe3.3

Γ from GC

  • ptical depth

radio band ICS

EGRET 5x30 EGRET 10x60 EGRET 1020 FERMI 1020

e e e e e e bestfit antiprotons unitarity bound ee 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 12 / 17

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SLIDE 16

Bounds on σannv from indirect dark matter searches: DM+DM → All

VL2

MED propagation

Γe3.3 ee ΜΜ ΤΤ WW bb

unitarity bound 10 50 100 500 1000 5000 1104 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020 1.1028 1.1027 1.1026 1.1025 1.1024 1.1023 1.1022 1.1021 1.1020

mDM GeV Σannv cm3s1

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 13 / 17

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SLIDE 17

Bounds on H from indirect dark matter searches

  • A naive bound comes from:

ΩDMh2 ∝ Hf σannvf

  • The correct calculation (Boltzmann equation):

˙ n + 3Hn = −σannv(n2 − n2

eq)

where H is a function of the temperature

  • In the following:
  • Parametric approach

H2 H2

GR

= 1 + η „ T Tf «ν tanh „T − Tre Tre «

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 14 / 17

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SLIDE 18

Bounds on H: Parametric approach

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 15 / 17

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SLIDE 19

Bounds on H: Parametric approach

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 16 / 17

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SLIDE 20

Conclusions

  • If dark matter is a thermal relic, the Hubble expansion can be constrained at

T ≫ TBBN

  • Indeed, present bounds on σannvf can be translated in bounds on Hf
  • These bounds depends on the assumed dark matter profiles and diffusion

model

  • However, for a 100 GeV WIMP

, large departures from GR (H/HGR > 100) are unlikely

Riccardo Catena (ITP) Paris (TeVPA 2010 22/07/2010) 17 / 17