Impact of Galactic subhalos on indirect searches with cosmic-ray antiprotons - TeVPA 2017 ·...
Transcript of Impact of Galactic subhalos on indirect searches with cosmic-ray antiprotons - TeVPA 2017 ·...
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Impact of Galactic subhalos Impact of Galactic subhalos on indirect searches on indirect searches
with cosmic-ray antiprotonswith cosmic-ray antiprotons
Martin Stref,
in collaboration with
J. Lavalle and T. Lacroix(LUPM, Montpellier, France)
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Cold Dark Matter SubhalosCold Dark Matter Subhalos
CDM structures at scales much smaller than typical galaxies
Mass of the first halos given by the kinetic decoupling of the dark matter particle
According to simulations, many small halos survive up to now :
[Bringmann 09,Berezinsky+ 14]
Aquarius simulation [Springel + 08],See also Via Lactea II [Diemand+ 08],Illustris [Vogelsberger+ 14]
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Subhalos and dark matter searches Subhalos and dark matter searches
DM annihilation
Earth position
Detection via photons, neutrinos or charged cosmic rays
Indirect searches:
Direct detection:
Xe nucleus
recoil
WIMPSensitive to the local DM density.Fraction of that density inside clumps?
If subhalos present in the galaxy, signal is boosted! [Silk & Stebbins 93]
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A dynamically constrainedA dynamically constrained model of model of
Galactic subhalosGalactic subhalos
Based on
Stref & Lavalle : arXiv:1610.02233
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A dynamically constrained GalaxyA dynamically constrained Galaxy
The Milky Way dark halo is tightly constrained by observations
Terminal velocities from McMillan 11
Mass models from McMillan 17
Sun position
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A dynamically constrained GalaxyA dynamically constrained Galaxy
The Milky Way dark halo is tightly constrained by observations
constrained modeled/predicted
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A dynamically constrained GalaxyA dynamically constrained Galaxy
The Milky Way dark halo is tightly constrained by observations
Subhalo mass function :
Aquarius simulation [Springel+ 08]
Press-Schechter type :
with mass cutoff
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A dynamically constrained GalaxyA dynamically constrained Galaxy
The Milky Way dark halo is tightly constrained by observations
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A dynamically constrained GalaxyA dynamically constrained Galaxy
The Milky Way dark halo is tightly constrained by observations
Tidal effects!
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Tidal effectsInteraction of subhalos with external gravitational fields.
Two different effects :
Halo stripping Disk shocking
Stellar diskV
z
Clump center
r
DM particles get a net velocity kick[Ostriker+ 72]
[Stref & Lavalle 17]
Subhalos are stripped by the potential of the Galaxy
[Binney & Tremaine 87]
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Number densityNumber density
Sun position
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Luminosity and boost factors
Sun position
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Indirect searches with Indirect searches with cosmic-ray antiprotonscosmic-ray antiprotons
Based on
Stref, Lacroix & Lavalle : arXiv:17xx.xxxxx
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Why antiprotons?Why antiprotons?
[Aguilar+ 16]
[Bergstrom 09]
Indirect searches :
with gamma rays[Bergstrom+ 99],
with antimatter cosmic rays [Lavalle+ 07,08]
f
AMS-02 data
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Why antiprotons?Why antiprotons?
[Cuoco+ 16, see also Cui+ 16]
[Bergstrom 09]
Indirect searches :
with gamma rays[Bergstrom+ 99],
with antimatter cosmic rays [Lavalle+ 07,08]
f
AMS-02 “hot spot”
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Cosmic-ray propagationCosmic-ray propagation[Mertsch, 2010]
Propagation eq. for cosmic rays sourced by DM
Propagation parameters fixed by B/C (secondaries/primaries) :
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Cosmic-ray propagationCosmic-ray propagation[Mertsch, 2010]
Propagation eq. for cosmic rays sourced by DM
L
Propagation parameters fixed by B/C (secondaries/primaries) :
r
Critical for DM searches
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Antiproton fluxAntiproton flux
Spectra from PPPC4DM ID[Cirelli+ 11]
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Exclusion curves : MED modelExclusion curves : MED model
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Exclusion curves : model of Kappl et al.Exclusion curves : model of Kappl et al.
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SummarySummary
● DM distribution is fondamental to make predictions on direct/indirect searches : dynamical constraints must be accounted for.
● Cold dark matter, and WIMPs in particular, forms very small-scale subhalos.
● The subhalo population can be modeled in a dynamically consistent way, including tidal disruption effects.
● Subhalos strongly impact indirect searches, e.g. with cosmic-rays antiprotons, and should be accounted for (at least as a theoretical uncertainty).
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BackupBackup
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Predicted mass density profilesPredicted mass density profiles
Sun position
Main model
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Posterior mass functionPosterior mass function
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Cored DM profileCored DM profile