Not So Weakly Interacting Dark Matter Bonding with Sterile Neutrinos Jörn Kersten Based on Torsten Bringmann, Jasper Hasenkamp, JK, JCAP 07 (2014) [arXiv:1312.4947]
Outline Introduction 1 Self-Interacting Dark Matter 2 Dark Matter Interacting with Neutrinos 3 3 / 21
Introduction 1 Self-Interacting Dark Matter 2 Dark Matter Interacting with Neutrinos 3 4 / 21
The Universe after Planck Flat Λ CDM cosmology fits data perfectly Planck, arXiv:1303.5062 5 / 21
The Universe after Planck Flat Λ CDM cosmology fits data perfectly Planck, arXiv:1303.5062 Or does it? Tensions in Λ CDM cosmology 5 / 21
Hints for Dark Radiation Dark radiation: relativistic particles � = γ, ν SM Parameterized via radiation energy density � � 4 � 7 � T ν ρ rad ≡ 1 + N eff ρ γ 8 T T ≡ T γ N eff : effective number of neutrino species Standard Model: N eff = 3 . 046 Existence of dark radiation ⇔ ∆ N eff ≡ N eff − 3 . 046 > 0 6 / 21
Hints for Dark Radiation Dark radiation: relativistic particles � = γ, ν SM Parameterized via radiation energy density � � 4 � 7 � T ν ρ rad ≡ 1 + N eff ρ γ 8 T T ≡ T γ N eff : effective number of neutrino species Standard Model: N eff = 3 . 046 Existence of dark radiation ⇔ ∆ N eff ≡ N eff − 3 . 046 > 0 Measurements of Cosmic Microwave Background (CMB): ∆ N eff = 1 . 51 ± 0 . 75 at 68 % CL ACT, ApJ 739 (2011) ∆ N eff = 0 . 81 ± 0 . 42 at 68 % CL SPT, ApJ 743 (2011) ∆ N eff = 0 . 31 + 0 . 68 − 0 . 64 at 95 % CL Planck, arXiv:1303.5076 6 / 21
Hints for Hot Dark Matter 2 . . . 3 σ tension: CMB ( z > 1000) vs. local ( z < 10) observations Expansion rate Planck: H 0 = ( 67 . 3 ± 1 . 2 ) km s Mpc arXiv:1303.5076 Hubble: H 0 = ( 73 . 8 ± 2 . 4 ) km s Mpc Riess et al., ApJ 730 (2011) Magnitude of matter density fluctuations ( σ 8 ) 7 / 21
Hints for Hot Dark Matter 2 . . . 3 σ tension: CMB ( z > 1000) vs. local ( z < 10) observations Expansion rate Planck: H 0 = ( 67 . 3 ± 1 . 2 ) km s Mpc arXiv:1303.5076 Hubble: H 0 = ( 73 . 8 ± 2 . 4 ) km s Mpc Riess et al., ApJ 730 (2011) Magnitude of matter density fluctuations ( σ 8 ) Resolved by hot dark matter component ≃ dark radiation Best fit: ∆ N eff = 0 . 61 � 3 � m eff T s s ≡ m s = 0 . 41 eV T ν Hamann, Hasenkamp, JCAP 10 (2013) Wyman, Rudd, Vanderveld, Hu, PRL 112 (2014) Battye, Moss, PRL 112 (2014) Gariazzo, Giunti, Laveder, JHEP 11 (2013) 7 / 21
Small-Scale Problems of Structure Formation Numerical simulations of structure formation with cold dark matter Springel, Frenk, White, Nature 440 (2006) � Excellent agreement with observations 8 / 21
Small-Scale Problems of Structure Formation Numerical simulations of structure formation with cold dark matter Springel, Frenk, White, Nature 440 (2006) � Excellent agreement with observations on large scales 8 / 21
Small-Scale Problems of Structure Formation Missing satellites Cusp-core Too big to fail Kravtsov, Adv. Astron. (2010) Boylan-Kolchin et al., De Blok et al., ApJ 552 (2001) Klypin et al., ApJ 522 (1999) MNRAS 422 (2011) More cuspy density More galactic Most massive profiles predicted satellites predicted satellites predicted than observed than observed denser than observed 8 / 21
Small-Scale Problems of Structure Formation Missing satellites Cusp-core Too big to fail Kravtsov, Adv. Astron. (2010) Boylan-Kolchin et al., De Blok et al., ApJ 552 (2001) Klypin et al., ApJ 522 (1999) MNRAS 422 (2011) More cuspy density More galactic Most massive profiles predicted satellites predicted satellites predicted than observed than observed denser than observed Astrophysics solutions or new particle physics? 8 / 21
Introduction 1 Self-Interacting Dark Matter 2 Dark Matter Interacting with Neutrinos 3 9 / 21
Not-so-WIMPy Dark Matter Dark matter χ Standard Model singlet Charged under U ( 1 ) X gauge interaction Mass m χ ∼ TeV χ χ Light gauge boson V , m V ∼ MeV � Long-range, velocity-dependent interaction . . . V � Less cuspy density profiles χ χ ¯ ¯ � Cusp-core and too big to fail solved Feng, Kaplinghat, Yu, PRL 104 (2010) Loeb, Weiner, PRL 106 (2011) Vogelsberger, Zavala, Loeb, MNRAS 423 (2012) 10 / 21
Velocity-Dependent Self-Interactions Described by Yukawa potential V ( r ) = ± α X r e − m V r Desired scattering cross section σ T : Large in dwarf galaxies Small on larger scales to satisfy experimental limits Very different behavior depending on model parameters 100 Σ T � m X � cm 2 � g � � attractive only � dwarf Milky Way cluster 10 7 �������������������� Classical Resonant Born 10 Σ T � m X � cm 2 � g � 1 10 4 0.1 10 10 � 2 0.01 10 � 3 Born m X � 200 GeV 10 � 5 r e Α X � 10 � 2 classical s o 10 � 4 n a n v � 10 km � s t 10 � 8 10 � 5 0.001 0.01 0.1 1 10 100 1000 m Φ � GeV � v � km � s � Tulin, Yu, Zurek, PRL 110 , PRD 87 (2013) 11 / 21
Velocity-Dependent Self-Interactions Described by Yukawa potential V ( r ) = ± α X r e − m V r Desired scattering cross section σ T : Large in dwarf galaxies Small on larger scales to satisfy experimental limits Very different behavior depending on model parameters 100 Σ T � m X � cm 2 � g � � attractive only � dwarf Milky Way cluster 10 7 �������������������� Classical Resonant Born 10 Σ T � m X � cm 2 � g � 1 10 4 0.1 10 10 � 2 0.01 10 � 3 Born m X � 200 GeV 10 � 5 r e Α X � 10 � 2 classical s o 10 � 4 n a n v � 10 km � s t 10 � 8 10 � 5 0.001 0.01 0.1 1 10 100 1000 m Φ � GeV � v � km � s � Tulin, Yu, Zurek, PRL 110 , PRD 87 (2013) Here: m χ v ∼ TeV 10 km / s 3 · 10 5 km / s ∼ 30 ≫ 1 m V MeV � classical regime � analytical approximations exist 11 / 21
Simulating Self-Interacting Dark Matter Simulation: formation of dwarf galaxy with dark matter + baryons 10 9 dA: SIDM10 DM:CDM-B stars:CDM-B DM:SIDM1-B stars:SIDM1-B DM:SIDM10-B stars:SIDM10-B DM:vdSIDMa-B stars:vdSIDMa-B DM:vdSIDMb-B stars:vdSIDMb-B ρ [M ⊙ kpc − 3 ] 10 8 10 7 dA 10 6 1 0 1 2 200 400 600 1000 3000 log[ ρ/ (M ⊙ kpc − 3 )] r [ pc ] Vogelsberger, Zavala, Simpson, Jenkins, MNRAS 444 (2014) � Core, size depends on strength of self-interactions 12 / 21
Introduction 1 Self-Interacting Dark Matter 2 Dark Matter Interacting with Neutrinos 3 13 / 21
Late Kinetic Decoupling Standard Model neutrinos coupled to V χ χ Dark matter scatters off neutrinos � T χ = T ν until kinetic decoupling at T ∼ 100 eV V � Formation of smaller structures suppressed ν ν � Missing satellites solved Van den Aarssen, Bringmann, Pfrommer, PRL 109 (2012) van den Aarssen, Bringmann & Pfrommer � 2012 � van den Aarssen, Bringmann & Pfrommer � 2012 � 5 5 5 5 m Χ � 10 TeV 70 not enough flattening m Χ � 500 GeV M � 60 7 0 1 of cuspy profiles 50 cutoff too small to M � 8 40 0 1 address abundance 1 1 1 1 M � m V � MeV � 30 m V � MeV � 9 0 1 problem � M 0.5 10 � 0.5 0.5 20 0 1 1 M � ruled out by 11 2 0 1 astrophysics 5 10 10 Ly �Α � 0.1 0.1 20 Σ max � m Χ � cm 2 g � 1 � excluded Υ max � km s � 1 � 0.05 0.05 1 10 10 � 5 10 � 4 10 � 3 10 � 2 10 � 1 m Χ � TeV � g Ν 14 / 21
Late Kinetic Decoupling Standard Model neutrinos coupled to V χ χ Dark matter scatters off neutrinos � T χ = T ν until kinetic decoupling at T ∼ 100 eV V � Formation of smaller structures suppressed ν ν � Missing satellites solved Van den Aarssen, Bringmann, Pfrommer, PRL 109 (2012) Problem: explicit breaking of SU ( 2 ) L van den Aarssen, Bringmann & Pfrommer � 2012 � van den Aarssen, Bringmann & Pfrommer � 2012 � 5 5 5 5 m Χ � 10 TeV 70 not enough flattening m Χ � 500 GeV M � 60 7 0 1 of cuspy profiles 50 cutoff too small to M � 8 40 0 1 address abundance 1 1 1 1 M � m V � MeV � 30 m V � MeV � 9 0 1 problem � M 0.5 10 � 0.5 0.5 20 0 1 1 M � ruled out by 11 2 0 1 astrophysics 5 10 10 Ly �Α � 0.1 0.1 20 Σ max � m Χ � cm 2 g � 1 � excluded Υ max � km s � 1 � 0.05 0.05 1 10 10 � 5 10 � 4 10 � 3 10 � 2 10 � 1 m Χ � TeV � g Ν 14 / 21
Enter the Sterile Neutrino Sterile neutrino N Mass m N ∼ eV χ χ Standard Model singlet Charged under U ( 1 ) X V Forms hot dark matter N N Dark matter scatters off sterile neutrinos 15 / 21
Enter the Sterile Neutrino Sterile neutrino N Mass m N ∼ eV χ χ Standard Model singlet Charged under U ( 1 ) X V Forms hot dark matter N N Dark matter scatters off sterile neutrinos � Everything solved All small-scale problems of structure formation Hot dark matter hint (CMB-local tension) Neutrino oscillation anomalies Bringmann, Hasenkamp, JK, JCAP 07 (2014) 15 / 21
Dark Matter Production High temperatures: U ( 1 ) X sector thermalized via Higgs portal L Higgs ⊃ κ | H | 2 | Θ | 2 � Θ � ∼ MeV breaks U ( 1 ) X 16 / 21
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