Probing the nature of Dark matter with radio astronomy. Céline Boehm

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1 Probing the nature of Dark matter with radio astronomy Céline Boehm IPPP, Durham LAPTH, Annecy SKA, Flic en Flac, May 2017

2 The DM Physics scale strong or weak / stable or decaying strong and stable Electromagnetic eg. e γ e γ σv! 6 25 cm 2 (< MeV) Supersymmetry Kaluza-Klein new interactions so new mediators Weak eg. e ν e ν σv 44 cm 2 (@MeV)

3 The good-old relic density argument Thermal dark matter annihilations are everything Hut, Lee&Weinberg 77 dn dt 2 2 3Hn v( n n0 ) Ωh cm 3 /s σv dm dm f f m v Ω DM h 2 m 2 m 2 dm 4 w σv! 3 26 cm 3 /s DM Dark Matter needs to be heavier than a proton to not over close the Universe

4 Supersymmetry Before 1998 We were going to discover the neutralino at LHC mdm <200 GeV

5 Three exceptions in the calculation of the relic abundances P. Salati Nucl.Phys. B237 (1984) hep-ph/98360 hep-ph/ χ τ X X χχ Y Ȳ τ τ Y Ȳ mdm > 200 GeV mdm > TeV Co-annihilations SUSY spectrum is either excluded or too heavy to be seen at LHC

6 SUSY survival mode Thermal dark matter who cares? actua!y does it have to annihilate into visible stuff? no! (FIMPs)

7 Particle DM: moving on from WIMPs

8 Going back to basics astro-ph/ , astro-ph/04591 t NR t dec t eq collisions decoupling Collisional Damping Free-streaming A3 2 ( l 2 id! 2 π 2 3 tdec(dm i) 0 ρ i v 2 i ρ t a 2 Γ i dt l fs = t0 t dec v a(t) dt

9 Free-streaming excludes < kev particles Thermal dark matter even when they are interacting!!! no dwarf galaxy Γ Region III self-interacting DM Region I sterile neutrino m DM 1/Γ dec = t eq Region II WIMPs-like t nr = t eq kev MeV astro-ph/ , astro-ph/04591

10 Light dark matter can have interactions and essentially suppress structure formation Thermal dark matter Γ Region III self-interacting DM Region I sterile neutrino m DM kev 1/Γ dec = t eq Region II WIMPs-like t nr = t eq MeV DM can be light, interacting and behave almost like WDM

11 Questioning the relic density argument Thermal dark matter does it have to be? no but! Hut, Lee&Weinberg 77 can DM be lighter than GeV? no but! astro-ph/ v3 hep-ph/ σv! 1 m 4 F σv! (( C 2 l + C 2 r ) mf +2C l C r m F ) 2 1 m 2 F vector-like fermions DM can be light! σv! v 2 m2 DM m 4 Z m DM m Z g 2 DM g 2 e dark photons/z DM can be light!

12 Introducing New Physics in general strong or weak / stable or decaying Electromagnetic eg. e γ e γ σv! 6 25 cm 2 (< MeV) new mediators new DM candidates Weak eg. e ν e ν σv 44 cm 2 (@MeV)

13 Gamma-ray constraints from our Milky Way astro-ph/ Courtesy T. Jubb INTEGRAL COMPTEL EGRET DM DM e e Fermi LAT 23 Σv cm 3 s Σv cm 3 s Prompt dsph CMB m DM GeV m DM GeV σv! v 2 m2 DM OK cm 3 s m 4 gdm 2 ge 2 σv! Z 24 INTEGRAL COMPTEL EGRET Fermi LAT 1 m 2 F DM DM b b OK but has to be suppressed

14 Combined constraints

15 Radio constraints from our Milky Way astro-ph/ arxiv: MHz excluded Sgr A* Excludes up to GeV particles for normal B field values

16 DM simplified models the couplings are free ; the masses too Modern version new!!!

17 Simplified models arxiv:

18 New DM-nuclei interactions new models ===> new couplings to nuclei! SI SD SD SD SI SD SD SI SD SD O1 NR O4 NR O6 NR O7 NR O8 NR O9 NR O NR O11 NR O13 NR O14 NR 1/2-S g f,s g χ,s g f,p g χ,p g f,p g χ,s g f,s g χ,p g f,s g χ,p 1/2*-V g f,v g χ,v g f,a g χ,a g f,a g χ,v g f,v g χ,a g f,a g χ,v 1/2-V g f,a g χ,a g f,v g χ,a 1/2-S ± gs 2 gp 2 gs 2 + gp 2 1/2*-S ± gs ± g 2 p 2 gs 2 + gp 2 1/2-V ± gv 2 ga 2 gv 2 + ga 2 1/2*-V ± gv ± g 2 a 2 gv 2 + ga 2 0-S g χ g f,s g χ g f,p 0-V g χ g f,v g χ g f,a g χ g f,a 0-F ± g s 2 ± g p 2 g p g s g s g p 0-F ± g s 2 ± g p 2 g p g s ± g s g p 1-S g χ g f,s g χ g f,p 1-V (V 1 ) Im(g χ )g v Im(g χ )g v Im(g χ )g a Re(g χ )g a Re(g χ )g v 1-V (V 2 ) Im(g χ )g v Im(g χ )g a Re(g χ )g a 1-V (V 3 ) Re(g χ )g a Re(g χ )g a Re(g χ )g v Re(g χ )g v Im(g χ )g v Im(g χ )g a 1-F ± g s 2 ± g p 2 g v g a + g a g v g v g a + g a g v g v g a g a g v 1*-F ± g s 2 ± g p 2 g v g a + g a g v g v g a g a g v g v g a + g a g v main operators new operators

19 Sebastian Wild s thesis Combining all

20 Indirect detection σv (cm 3 s 1 ) DES J DES J DES J DES J DES J DES J DES J DES J Combined DES Candidate dsphs Combined Known dsphs 26 Thermal Relic Cross Section (Steigman et al. 2012) faint objects which are DM dominated 27 τ + τ DM Mass (GeV/c 2 )

21 Where are we heading to? The role of radio astronomy

22 Annihilation signals in our Milky Way arxiv: Low frequency Astrophysical sources DM Low frequency Sum of the contributions 40 GeV DM High frequency High frequency Figure 2. Synchrotron maps for 40 GeV dark matter particles, B =3µG. We use the MED parameter set and assume annihilating particles. see prospects for SKA: arxiv:

23 Centaurus A arxiv:

24 Reticulum II Excess of gamma-rays (GeV range) but also 511 kev and radio arxiv: background in black Integral/SPI exposure map Figure1: Exposuremap after ten years(1258 orbits) of INTEGRAL/ SPI observations, in unitsof cm 2 s. The effect ive area of SPI at phot on energies around 511 kev is about! 75 cm 2. Ret II is located at (l/ b)= ( / " )withanexposureof250ks.fromsiegertetal.(2016a)[2]. Courtesy: T. Siegert Samet h et al. (2015) [] report ed a 2.3 t o 3.7! excess in 2- GeV gamma-rays which may eit her be interpreted as due to annihilation of DM particles or could be associated with cosmic-ray/gas interactions. The visible detection of Ret II was a result of analysing dat a from t he DES [1]. T he DES intends to study the accelerated expansion of the Universe as discovered by Riess, Perlmutter, and Schmidt [11, 12], which is subst ant iat ing t he st andard cosmological model ΛCDM. Here, the Universe consists of about 70% dark energy (Λ), and about 30% mat t er. T he lat t er ingredient is believed to be about 80% DM, which may have decoupled Flux [ 5 ph cm 2 s 1 (0.5 kev) 1 ] kev Energy [kev]

25 Spikes in the DM density distribution ( ) Conservation of momentum in adiabatic growth from initial to final state rv(r) =cst } ular momentum of eac 9 2γ v(r) =(GM(r)/r) 1/2 γ sp =!! i (r)r 2 r f 4 γ. dr =! f (r)r 2 dr, m of the masses of the D! r i 0 profile, assumed to follow a po 0 ge of slopes expect NFW: 7/3 inner slope ρ sat = m DM σv t BH ch is conservatively gure 9.1: DM energy density as a function of the distance from the center, for a DM sp + spikes can be destroyed by galaxy dynamics. stellar heating (+ mergers, non adiabatic contraction)

26 Implication of a DM spike for the MW while the NFW case is shown in the right panel. synchrotron emission of electrons and positrons Chapter 7. Figure 7.1: 30 GHz maps of the synchrotron intensity induced by GeV DM particles, for σv =3 26 cm 3 s 1, B =3µG, and the MED set of propagation parameters. The DM profiles used are a spiky profile with γ sp =7/3, R sp =1pc,withr sat = rsat ann (left panel), and Chapter 7. Probing a DM spike at the GC in the presence of spatial electron diffusion1 the NFW profile (right panel). Probing a DM spike at the GC in the presence of spatial electron diffusion121

27 Black Hole shadow with EHT arxiv: synchrotron emission of electrons and positrons GeV DM annihilating into bb G spike no spike EHT will access angular scales as small as 26 µas at 230 GHz and 17 µas at 345 GHz.

28 arxiv: arxiv: C.B., J. Schewtschenko et al (factor 0 better than CMB) (same with neutrinos) The local Universe constrains Particle Physics interactions!!!

29 Conclusion Radio astronomy can probe the parameter space heading toward higher masses and/or weaker interactions (unless the DM only interacts in the dark sector) Still anomalies : will SKA help? Cen A, Ret II DM annihilations near BH MW, M87, BH shadow will SKA help? Power Spectrum new models & H0