Constraining Dark Matter with Background Light Sam McDermott Dec 5, LANL from 1309.4091, with Rouven Essig, Eric Kuflik, Tomer Volansky, and Kathryn Zurek and 1312.0608 with Ilias Cholis and Dan Hooper
Prelude LUX sees nothing Is this really a big problem? See e.g.: Cirigliano, Graesser, Ovanesyan, and Shoemaker 1311. 5886; Gresham and Zurek 1311.2082
Motivation • More and more of our favorite DM parameter space seems to be getting ruled out • (Infinitely) large swaths of well-motivated DM parameter space are currently up for grabs • We need complementary probes to • test assumptions of bounds • explore different parameter space • This talk will focus on indirect detection
Motivation • Photons (produced directly, from FSR, from cascades, etc.) are generic in DM annihilation and decay • Data are “just sitting there” ready to use This talk two very different methods of approaching this problem
Outline • Light decaying dark matter: • models • statistical methodology • results • “Light” annihilating dark matter: • isotropic gamma rays from DM • astrophysical backgrounds • results
Part I: Light (MeV-ish) Decaying DM
“Light” Dark Matter • still cold • not warm, not an ALP that forms a galactic scale BEC, etc. • few keV to few GeV mass • we assume that all (model-dependent) observables of standard cosmology are taken care of (i.e., asymmetric or thermal production where appropriate)
Data • “Diffuse” X-Rays and Gamma-Rays • HEAO-1 (1977) • INTEGRAL (2008) • COMPTEL (1998) • EGRET (2003) • Fermi (2012) (21 months) • Some observations near the galactic poles, some near the galactic center
Data HEAO - 1: { Œ H 58,109 L‹H 238,289 L , » b » Œ H 20,90 L INTEGRAL: » { » Œ H 0,30 L , » b » Œ H 0,15 L E g 2 d F ê dE g @ MeV cm - 2 s - 1 sr - 1 D COMPTEL: » { » Œ H 0,60 L , » b » Œ H 0,20 L EGRET: { Œ H 0,360 L , » b » Œ H 20,60 L FERMI: { Œ H 0,360 L , » b » Œ H 8,90 L 0.01 10 - 3 0.01 0.1 1 10 10 2 10 3 10 4 E g @ MeV D
Analysis methods • There are many different methods: • spectral fit plus power law in sliding energy window (cf. Weniger) • precise background modeling (cf. Siegal-Gaskins; newer work here; others) • “on-off” or template analyses (cf. Koushiappas + Geringer-Sameth; Finkbeiner + Slatyer; Hooper + Slatyer; Tempel, Hektor, + Raidal; others)
Analysis methods • There are many different methods: requires • spectral fit plus power law in sliding exceptional energy energy window (cf. Weniger) resolution • precise background modeling (cf. Siegal-Gaskins; newer work here; others) • “on-off” or template analyses (cf. Koushiappas + Geringer-Sameth; Finkbeiner + Slatyer; Hooper + Slatyer; Tempel, Hektor, + Raidal; others)
Analysis methods • There are many different methods: • spectral fit plus power law in sliding requires energy window (cf. Weniger) detailed • precise background modeling knowledge of astrophysics (cf. Siegal-Gaskins; newer work here; others) over very wide • “on-off” or template analyses ranges of (cf. Koushiappas + Geringer-Sameth; Finkbeiner + position and Slatyer; Hooper + Slatyer; Tempel, Hektor, + energy space Raidal; others)
Analysis methods • There are many different methods: • spectral fit plus power law in sliding energy window (cf. Weniger) • precise background modeling (cf. Siegal-Gaskins; newer work here; others) • “on-off” or template analyses requires exceptional (cf. Koushiappas + Geringer-Sameth; Finkbeiner + Slatyer; Hooper + Slatyer; Tempel, Hektor, + angular Raidal; others) resolution
Analysis methods • There are many different methods: • spectral fit plus power law in sliding energy window (cf. Weniger) • precise background modeling (cf. Siegal-Gaskins; newer work here; others) • “on-off” or template analyses (cf. Koushiappas + Geringer-Sameth; Finkbeiner + Slatyer; Hooper + Slatyer; Tempel, Hektor, + Raidal; others)
Our analysis (1309.4091) • Only direct photon production and primary FSR; no ICS, synchrotron, etc. • We simply require (for every energy bin): Flux predicted ≤ Flux observed + 2 × Error Bar observed • Robust results!
Our analysis (1309.4091) • Only direct photon production and primary FSR; no ICS, synchrotron, etc. • We simply require (for every energy bin): Flux predicted ≤ Flux observed + 2 × Error Bar observed • Robust results!
Can we exclude this? 20.0 15.0 Flux Γ @ arb. units D 10.0 7.0 5.0 3.0 2.0 1.5 1.0 3.0 5.0 7.0 10.0 E Γ @ arb. units D
With background model, sure Power law 20.0 background 15.0 Flux Γ @ arb. units D 10.0 7.0 5.0 3.0 2.0 1.5 1.0 3.0 5.0 7.0 10.0 E Γ @ arb. units D Signal
With background model, sure Power law 20.0 background 15.0 Flux Γ @ arb. units D 10.0 But what if the 7.0 background does 5.0 3.0 something crazy? 2.0 1.5 1.0 3.0 5.0 7.0 10.0 E Γ @ arb. units D Signal
Being conservative: Not ruled out! 20.0 15.0 Flux Γ @ arb. units D 10.0 “Conspiracy” 7.0 background 5.0 3.0 2.0 1.5 1.0 3.0 5.0 7.0 10.0 E Γ @ arb. units D Signal
Being conservative: Not ruled out! 20.0 15.0 We are being Flux Γ @ arb. units D 10.0 “Conspiracy” 7.0 robust at the cost background 5.0 of ruling out less 3.0 parameter space 2.0 1.5 1.0 3.0 5.0 7.0 10.0 E Γ @ arb. units D Signal
Photons from DM decays d Φ γ , G = r � Γ dN γ ρ � Galactic: dE J ( Ω ) 4 π dE m DM vs. extragalactic: Z ∞ 1 d Φ γ ,EG = Ω ΓΩ DM ρ c dN dz p 4 π dE ( z ) dE m DM a 0 H 0 Ω Λ + Ω m (1 + z ) 3 0 Galactic dominates, marginally: ρ � r � J ( Ω ) ' O (10 � 5 GeV 3 ) vs . ρ DM /H 0 ' 5 ⇥ 10 � 6 GeV 3 but same order of magnitude
Models of decaying DM • Hidden Photino – SUSY + hidden U(1). [Higgs a hidden U(1); break SUSY with messengers from SM; hidden photon/photino with small mass splitting; kinetically mix hidden photon and photon of U(1)EM. Decays involving SM possible if there is a light gravitino. Topology depends on relative masses of hidden photon/photino.] • Sterile Neutrino – long-lived sterile neutrino • RPV Gravitino – neutrino/photino mixing. [Planck-scale suppression gives a naturally small rate for gravitino decays. Fastest decay is gravitino > photon + neutrino.] • Plus dipole DM, dark scalar, dark pseudoscalar
So the name of the game is... Ignore the astro/cosmology stuff (be conservative) Particle physics enters through and only: dN/dE γ Γ dN/dE γ is fixed by decay topology is fixed by the model Γ
Dark photino model MeV scale comes out naturally: ! 2 ⌘ ⇣ g d ⌘ p h D Y i γ d = ✏ · g d h D Y i ' (5 MeV) 2 ⇣ ✏ m 2 e 10 − 8 0 . 2 50 GeV Two different decays, depending on whether the dark photon or dark photino is more massive: p ! 4 ◆ 5 ◆ 2 ✓ 10 MeV ✓ 10 − 8 F G ' 3 ⇥ 10 23 sec ⌧ e γ d → γ e m e 100 TeV ✏ γ d p ! 4 ! − 4 ◆ 5 1 � m 2 ✓ 1 MeV F G ' 3 ⇥ 10 20 sec γ d τ e γ d → γ d e 10 4 TeV m 2 m e DM γ d
Dark photino DM, m e γ d < m γ d p ! 4 ◆ 5 ◆ 2 ✓ 10 MeV ✓ 10 − 8 F G ' 3 ⇥ 10 23 sec ⌧ e γ d → γ e m e 100 TeV é ✏ é γ d d Æg G g 0.01 Short - Lived 10 - 4 10 - 6 e 10 - 8 F = 10 4 TeV √ HEAO - 1 INTEGRAL 10 - 10 COMPTEL EGRET 10 - 12 FERMI 0.1 1 10 10 2 10 3 10 4 m g d @ MeV D é
Dark photino DM, m e γ d > m γ d p ! 4 ! − 4 ◆ 5 1 � m 2 ✓ 1 MeV F G ' 3 ⇥ 10 20 sec γ d τ e γ d → γ d e 10 4 TeV m 2 m e DM γ d é Æ f + f - G é é d Æg d G g HEAO - 1 10 6 m g d < m G é + m g d é INTEGRAL COMPTEL EGRET F @ TeV D 10 5 Short - 10 4 Lived 1 10 10 2 m g d @ MeV D é
Sterile neutrino DM Three-body and radiative decays contribute to photon background at similar levels: mixing angle between and ν e ν s ◆ 5 ✓ sin 2 2 θ ◆ − 1 ✓ 10 MeV τ ν s → νγ ' 7 . 2 ⇥ 10 17 sec 10 − 8 m χ ◆ 5 ✓ sin 2 2 θ ◆ − 1 ✓ 10 MeV τ ν s → ν α e + e − ' 9 . 6 ⇥ 10 15 sec 10 − 8 m χ
Sterile neutrino DM Relic abundance is model-dependent, but a UV-insensitive contribution comes from late-time oscillations (Dodelson-Widrow mechanism) Bounds are different depending on whether or . Ω ν s = Ω DW Ω ν s ≥ Ω DW
Sterile neutrino DM n s H radiative and three - body decays L W n s ≥W DW 10 - 8 W s >W DM 10 - 10 SN1987A 10 - 12 Short - CMB 10 - 14 Lived n s H radiative and three - body decays L 10 - 16 W n s =W DW BBN 10 - 18 sin 2 2 q 10 - 8 10 - 20 Ly -a Ly -a W s >W DM 10 - 22 SN1987A 10 - 10 10 - 24 HEAO - 1 10 - 12 10 - 26 Short - INTEGRAL CMB Lived 10 - 28 10 - 14 COMPTEL sin 2 2 q 10 - 30 EGRET 10 - 16 10 - 32 BBN 10 - 18 0.01 0.1 1 10 10 2 HEAO - 1 10 - 20 m n s @ MeV D INTEGRAL 10 - 22 COMPTEL 10 - 24 EGRET very strong! 0.01 0.1 1 10 10 2 m n s @ MeV D
RPV gravitino DM ! − 1 γν | 2 m 3 ◆ 2 ◆ 3 ✓ 10 − 4 ✓ 10 MeV 1 ' 3 . 8 ⇥ 10 28 sec 3 / 2 32 π | U e G → νγ = τ e m 2 m 3 / 2 U e Pl é Æng γν G 1 Short - 0.1 ν Lived 0.01 × � 10 - 3 G � γ é n 10 - 4 U g 10 - 5 10 - 5 HEAO - 1 INTEGRAL 10 - 6 10 - 6 γ COMPTEL 10 - 7 10 - 7 EGRET FERMI 10 - 8 10 - 8 0.1 1 10 10 2 10 3 10 4 m 3 ê 2 @ MeV D
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