1. Theoretical Astroparticle Physics
keV sterile neutrinos
Solar Axions: CAST
Axion Dark Matter
Supernova Neutrinos
Theoretical Astroparticle Physics
Georg G. Raffelt
MPI für Physik

2. Theoretical Astroparticle Group
Emeritus
(also CRESST)
G.Raffelt
H.Vogel
I.Izaguirre
E.Vitagliano
M.Berrer
L.Stodolsky
U Basel
Mondays
at MPP
A.Merle
M.Totzauer
T.Geib
J.Koenig
M.Volpp
S.Antusch
Soon gone
to Durham
for PhD
U Zaragoza
1 week/month
at MPP
(MADMAX)
F.Steffen
A.Millar
J.Stadler
J.Redondo
PhD at Yaroslavl
(Russia)
50% at MPP
TIFR Bombay
Max Planck
Partnergroup
since June 16
A.Dobrynina
B.Dasgupta

3. White Paper keV-mass sterile neutrinos
Alexander Merle
and students:
keV-mass sterile nus
models & cosmology
Susanne Mertens
MPG Research Group
Experimental search for
keV-mass sterile nus

4. Sterile Neutrinos as Dark Matter
Sterile neutrinos have non-thermal spectra (beyond hot, warm, cold!)
THERMAL
HOT
WARM/COOL
COLD
NON-THERMAL
THUS:
Important implications for cosmic structure formation!!!

5. Astroparticle Group leading in, for example,
DM production on the level of distribution functions
Consequences for cosmic structure formation
Connection to active-neutrino phenomenology
[AM, Totzauer: JCAP 1506 (2015) 011]
[König, AM, Totzauer: 1508.XXXXX]

6. Pie Chart of Dark Matter of the Universe
Dark Energy 70%
(Cosmological Constant)
Neutrinos %
Ordinary Matter 5%
(of this only about
10% luminous)
Dark Matter
25%

7. Axion and Axion-Like Particle Searches
ARIADNE
Center for Axion & Precision Physics (KAIST, Korea)
WISP
DMX
(DESY)
MAGIC
MADMAX at MPP
ADMX-HF
XXX (Yale)
Axion Dark Matter
Experiment
(UW, Seattle)
H.E.S.S.
IAXO Proposal
(CERN, DESY, …?)
CASPEr, HIM (Mainz)
Fermi LAT
CERN

8. CAST Results – Solar Axions Finished 2015
2003 – 2004
CAST phase I
vacuum in the magnet bores
2006
CAST phase II - 4He Run
axion masses explored up to eV (160 P-steps)
2007
3He Gas system implementation
CAST phase II - 3He Run
axion masses explored up to 1.17 eV
bridging the dark matter limit
2012
Revisit 4He Run with improved detecors
Revisit vacuum phase with improved detectors
Analisis ongoing.
New result soon available P
phase II-3He
phase II-4He
phase I
Dark Matter 2016, Santander
Igor G. Irastorza /
Universidad de Zaragoza

9. Javier Redondo (Mercator fellow, U Zaragoza)
Proposed CRC 1258 at TUM: Neutrinos, Dark Matter and Astro Messengers (NDM)
Axion Dark Matter
New experimental search, phenomenological
motivation and theoretical background
PIs: Allen Caldwell (MPP), Georg Raffelt (MPP), Patrick Vaudrevange (TUM)
Javier Redondo (Mercator fellow, U Zaragoza)
D05
Peccei-Quinn mechanism to relax Q-term:
– Solves CP problem of QCD
– Dark matter as axion field oscillations
– Boost in world-wide interest
– No experimental search in Europe
PQ symmetry breaking after inflation:
– Axions from re-alignment and relaxation
of cosmic axion strings and domain walls
– Expect ma in 100 meV (25 GHz) range
Questions and work packages:
A. Novel search technique in 25 GHz range
B. Phase-space distribution (mini clusters, ...)
C. Top-down model building (string axions)

10. Layered Dielectric Haloscope (MADMAX Project)
Javier Redondo’s idea
(now U Zaragoza)
May turn up axion dark matter!
Axion de Broglie wave length (ma = 100 meV)
𝝀 𝒂 ∼ 𝟐𝝅 𝒎 𝒂 𝒗 𝐠𝐚𝐥 =𝟏𝟐.𝟒 𝐦
Apparatus in B-field
∼𝟏 𝐦𝐞𝐭𝐞𝐫
Photon wave length (25 GHz Microwave)
𝝀 𝜸 ∼𝟏.𝟐𝟒 𝐜𝐦

11. Neutrino Flavor Evolution in Supernovae
Crab Nebula
Neutrino Flavor Evolution in Supernovae
• Core-collapse supernova physics driven by neutrinos
• Flavor-dependence of energy and lepton-number transport
• Flavor evolution in dense neutrino background poorly understood

12. Self-Induced Flavor Conversion
• Pair-wise flavor exchange
by n-n refraction on
forward-scattering level
• Does not necessarily require
neutrino mixing
• Self-induced flavor conversion occurs
in deep SN layers?
• “Turbulence in flavor space”
on small length scales?
• Crucial for understanding
flavor-dependent transport of
energy and lepton number in SNe

13. Inner Space – Outer Space
Inner neutrino properties:
Majorana property, mass hierarchy,
eV or keV sterile states, …
Theory and Observation of Sources:
SN Explosion, NS Mergers, Cosmology,
Nucleosynthesis, HE Nu Propagation n
3D Supernova
Simulation
(Janka et al.,
MPA Garching)

14. Getting to the Guts of Neutrinos!
Inner neutrino properties:
Majorana property, mass hierarchy,
eV or keV sterile states, …
Theory and Observation of Sources:
SN Explosion, NS Mergers, Cosmology,
Nucleosynthesis, HE Nu Propagation n
3D Supernova
Simulation
(Janka et al.,
MPA Garching)