[PPT] - INDIRECT DARK MATTER SEARCHES IN ICECUBE WIN2017, UC IRVINE 2 DM PowerPoint Presentation

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INDIRECT DARK MATTER SEARCHES IN ICECUBE

MORTEN MEDICI

WIN2017, UC IRVINE

Photo: NSF/Hans Boenish

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DM SEARCHES IN ICECUBE MORTEN MEDICI

INDIRECT DETECTION WITH NEUTRINOS

ν ν

low concentration high concentration

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Indirect

dark matter b, W, τ dark matter b, W, τ ν’s ν’s

Stars: C. Beckett, S. Meneguolo, Royal Astronomical Society of Canada,   Milky Way: Trevor Jones, Earth: NASA

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DM SEARCHES IN ICECUBE MORTEN MEDICI

INDIRECT DETECTION WITH NEUTRINOS

Indirect

dark matter b, W, τ dark matter b, W, τ ν’s ν’s

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ν ν

low concentration high concentration

Stars: C. Beckett, S. Meneguolo, Royal Astronomical Society of Canada,   Milky Way: Trevor Jones, Sun: NOAA/CosmicQuest

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DM SEARCHES IN ICECUBE MORTEN MEDICI

NEUTRINO PHYSICS WITH ICECUBE

▸ 1 km3 instrumented ice below  

the South Pole (finished 2010)

▸ 5160 light sensors for detecting 

Cherenkov radiation

▸ Measuring neutrino-initiated 

events

▸ Energies down to 10s GeV ▸ Stable operation and reliable  

hardware (> 99% livetime) neutrino charged particle

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DM SEARCHES IN ICECUBE MORTEN MEDICI

SIGNAL AND BACKGROUND

▸ Background at trigger level ▸ Atm. muons: 1011/year ▸ Atm. neutrinos: 105/year ▸ Dark matter searches ▸ Sun: +/- 23o above horizon ▸ Galactic center: 29o above horizon

neutrino IceCube muon

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cosmic rays

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ICECUBE EVENTS

▸ Two topologies: ▸ Tracks (best pointing) ▸ Cascades (contain all energy) ▸ Reconstruct neutrino:

Charge, time, geometry Direction, energy, position

Science 342, (2013)

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GALACTIC HALO

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DM SEARCHES IN ICECUBE MORTEN MEDICI

TARGETED SIGNAL FROM GALACTIC HALO

▸ Spectrum model dependent ▸ Signal sensitive to 

assumed halo profile

102 101 100 101 102 Radius [kpc] 103 102 101 100 101 102 103 104 Density [107M/kpc3]

Burkert NFW

20 40 60 80 100 120 Eν [GeV] 10−6 10−5 10−4 10−3 10−2 10−1 100 101 dN/dEν Spectrum of νµ mDM = 100 GeV

b¯ b W +W − µ+µ− τ +τ − ν¯ ν

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ANALYSIS TECHNIQUE

▸ Likelihood approach with a mixture of: ▸ Signal: Modelled from simulated neutrino events

weighted to correspond to dark matter annihilation

▸ Background: Estimated from exp. data ▸ Signal contamination in background is subtracted ▸ Same approach used across all presented galactic halo

analyses

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LATEST UPDATE ON ANALYSES

▸ Covering dark matter masses  

from 10 GeV to 300 TeV

▸ Exploiting three different event selections, each optimised

for a specific class of events

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IC 3yr GC tracks IC 4yr PS+3yr MESE IC 2yr cascades

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DM SEARCHES IN ICECUBE MORTEN MEDICI

LOW ENERGY ANALYSIS

▸ Dark matter masses between 10-1000 GeV ▸ Using the finished IceCube with 86 strings ▸ Exploiting good pointing resolution of the muon tracks ▸ Implementation of new event reconstruction important

below neutrinos energies of 100s of GeV

▸ 3 years of data: 1007 days of livetime ▸ Results submitted and public  

[arXiv:1705.08103]

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IC 3yr GC tracks IC 4yr PS+3yr MESE IC 2yr cascades

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DM SEARCHES IN ICECUBE MORTEN MEDICI

HIGH ENERGY TRACK ANALYSIS

▸ Dark matter masses between 0.3-1000 TeV ▸ Using tracks from IceCube dataset designed for point  

source searches (PS)

▸ Focus on galactic halo makes it less effected by the dark matter

halo profile assumptions

▸ Includes an IceCube dataset dedicated to the southern

hemisphere (MESE)

▸ Inclusion of energy in likelihood analysis  

provides extra sensitivity above 10s TeV

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IC 3yr GC tracks IC 4yr PS+3yr MESE IC 2yr cascades

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DM SEARCHES IN ICECUBE MORTEN MEDICI

HIGH ENERGY CASCADE ANALYSIS

▸ Dark matter masses between 3-300 TeV ▸ Exploiting the good energy resolution from contained

cascades

▸ Inclusion of energy provides extra sensitivity above 10s TeV ▸ Using an IceCube dataset designed for an unfolding

analysis of the neutrino spectrum

▸ Implementing a progressively larger veto  

for lower energy events

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IC 3yr GC tracks IC 4yr PS+3yr MESE IC 2yr cascades

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▸ No excess above the expected background was seen

DM SEARCHES IN ICECUBE MORTEN MEDICI

GENERAL SUMMARY: GALACTIC HALO WIMPS

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▸ Assuming Burkert dark matter halo profile

DM SEARCHES IN ICECUBE MORTEN MEDICI

GENERAL SUMMARY: GALACTIC HALO WIMPS

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SOLAR SEARCH

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TARGETED SIGNAL FROM THE SUN

▸ Accumulation of WIMP in the sun, assumed to 

be in equilibrium with the annihilation rate

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SOLAR WIMP STUDIES

▸ New results using the finished IceCube 

with 86 strings

▸ Results published:  

EPJC 77 146 (2017) [arXiv:1612.05949]

▸ 3 years of data: 532 days of livetime ▸ Two independent analyses focusing on high and low dark

matter mass

▸ No excess above the expected background

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SOLAR WIMP STUDIES

▸ Presents very competitive bounds on the  

spin-dependent nucleon-dark matter interaction cross-section

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SOLAR WIMP STUDIES

▸ pMSSM model scans, indicating the fraction of  

hard and soft final states

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DECAYING  DARK MATTER

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DM SEARCHES IN ICECUBE MORTEN MEDICI

DECAYING DARK MATTER STUDIES

▸ Dark matter signal: Galactic halo and isotropic extragalactic component ▸ Background: Atmospheric muons/neutrinos and astrophysical neutrinos ▸ Analysis fit: Dark matter mass/lifetime, isotropic astrophysical flux/index ▸ Two independent analyses using event selections designed for unfolding the

neutrino spectrum:

▸ 1) Using dataset with 6 years of northern hemisphere tracks ▸ 2) Using dataset with 2 years of full sky cascades ▸ Focusing on the Hν- or Zν-channel which has a significant peak in energy from the

neutrino line spectrum

▸ No excess above the expected background

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EXPERIMENTAL LIMITS ON DECAYING DARK MATTER

▸ Adding limits on dark matter lifetime for dark matter masses

above 10 TeV for high mass dark matter

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SUMMARY

▸ No observation of a neutrino signal in IceCube  

compatible with dark matter annihilation

▸ More sensitive analyses and longer reach in dark matter masses

provides very competitive limits on the annihilation cross section

▸ IceCube is less sensitive to the exact distribution of dark matter

in the galactic halo.

▸ Solar dark matter searches result in world strongest bound on

the spin-dependent dark matter-nucleon interaction cross section

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THANKS FOR YOUR ATTENTION!

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SOLAR WIMP STUDIES

▸ Spin-independent dm-nucleon cross section

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DECAYING DARK MATTER

▸ Significant excess of 

high energy neutrinos   above backgrounds

▸ Used to look for decaying 

heavy dark matter

2.0 PeV 1.1 PeV 1.0 PeV

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