Dark Matter - II - KIT · Fermi –Large Area Telescope LAT ... 3-year data taking with FERMI...

KIT – University of the State of Baden-Württemberg and

National Research Center of the Helmholtz Association

Guido Drexlin, Institut für Experimentelle Kernphysik

www.kit.edu

Guido Drexlin, Institut für Experimentelle KernphysikGuido Drexlin, Institut für Experimentelle Kernphysik

Dark Matter - II

GRK 1694: Elementarteilchenphysik bei höchster Energie und höchster Präzision

Workshop Freudenstadt 2015

September 30, 2015

shedding (Cherenkov) light on dark matter

KIT-IEKP2 Sept. 30, 2015 G. Drexlin – DM1

WIMP candidates

log c

ross

section

(sin

t/1pb

)

neutrino cross section:

sn,EW = 10-44 … 10-40 cm2

= 10-8 … 10-4 pb

Standard Model particles:

0

-5

-10

-15

-20

-25

-30

-35

-40

supersymmetric particles:

neutralino cross section:

sc = 10-48 … 10-42 cm2

= 10-12 …10-6 pb

~ 10-2 sn,EW

suppressed relative to sn,EW

due to mixing effects-12 -6 0 6 12 18

keV GeV MGUT MPl

neutralino c

MSSM

WIM

P

sEW < 1 pb ( = 10-36 cm2 )

energy-dependent

weak interaction neutrino n

log particle mass (M / 1GeV)


WIMP candidates

0

-5

-10

-15

-20

-25

-30

-35

-40

-12 -6 0 6 12 18

keV GeV MGUT MPl

MSSM

WIM

P

sEW < 1 pb ( = 10-36 cm2 )

energy-dependent

weak interaction


log c

ross

section

(sin

t/1pb

)

neutrino n


axino

keV GeV MGUT MPl

gravitino

WIM

Pzill

a

axion

axino

axion

gravitino

WIMPzilla

0

-5

-10

-15

-20

-25

-30

-35

-40

neutrino n

-12 -6 0 6 12 18

Neutralino c

MSSM

WIM

P

light (10-6…10-3 eV) WIMP,

produced by non-thermal

processes, solves the strong

CP-problem (Peccei-Quinn)

SUSY partner of axion, from

decays of SUSY particles

SUSY partner of graviton, only

gravitational interaction

extremly massive, non-thermal

relics (curvature effects)

log c

ross

section

(sin

t/1pb

)


WIMP candidates


outline of today´s lecture

Dark Matter – 2: indirect searches for dark matter

- modelling of physics (signal)

- modelling of astrophysics (halo, background)

- messenger particles: gammas, positrons, anti-protons, neutrinos

- FERMI gamma-ray observatory

- GeV-excess @ GC: a model case for signal & background

- gammas at the TeV-scale: Atmospheric Cherenkov Telescopes

- charged messengers & neutrinos


f f

LH

C

generation of

neutralinos at

LHC

directscattering of

galactic

neutralinos

in detector

c0 c0

-

~

experimental WIMP searches

indire

ct

annihilation of

neutralinos in

CDM halos


indirect detection methods

Indirect detection of CDM: observation of secondary particles from

WIMP annihilation processes in the local group of galaxies

c0

supersymmetric

neutralinos

low-energy

photons

leptons

e,µ,t

quarks

u,d

gauge bosons

W,Z0decay

c0

positrons

electrons

electrons/positrons from:

- hadronic decays

- pair production

- direct production

antiprotons

protons

protons/antiprotons from:

- hadronisation & jets

- decays of gauge boson

gamma rays

gamma rays

gammas from:

- hadronic decays

- bremsstrahlung

neutrinosneutrinos from:

- hadronic/leptonic decays

_- gammas (g), neutrinos (n), antiprotons (p) & positrons (e+)


detection of WIMP annihilation requires precise modelling of

a) c0-signal: particle physics (decay modes)

WIMP annihilation

WIMP annihilation – modelling of signal

how: WIMP decays into quarks, leptons, bosons


annihilation into fermion pairs (quarks, Leptons)

annihilation into gauge boson pairs W± Z0

Neutralino annihilation processes

s-channel

s-channel

- Z0 boson

- pseudoscalar Higgs A

t-channel: charginos, neutralinos

c

c

Z0

fA

c

c

c

cf_

f

f_

f

f_

f_

c

c

c

W

W

c+

c

c

c

Z0

h,H

W

W

W

W

c

c

Z0

Z0

cn

cn

h,H

c

Z0

Z0

c

t-channel

t-channel

- sfermions


…an extract of further

annihilation channels…

Neutralino annihilation processes


Neutralino annihilation c0 c0 → qq : fragmentation of quarks

leads to ~30-40 gammas (GeV-energies)

~ ~ _

Spektren für m(c0) = 100 GeV

0.1 1 10 100

g-energy (GeV)

E2

·flux

(Ge

V c

m-2

s-1

sr-

1)

10-2

10-3

10-4

10-5

10-6

10-7

10-8

bb

Z0Z0

W+W-

t+t-

_

cc_

- decay channels depend on:

a) WIMP mass M(c0)

b) WIMP flavour composition

(bino, wino, higgsino)

- c0-decays to light quarks u,d,…

(and massless g´s) are

helicity suppressed

M = 100 GeV

gamma spectrum depends on annihilation channel (→ bb, ZZ)

Gammas from WIMP annihilations



a) c0-signal: particle physics (decay modes)

WIMP annihilation – modelling of signal

where: NFW halo profile (triaxial halo, sub-halos) ?

& astrophysics (halo model)


DMA-sources & halo profile

sightofline

CDMAnn dsN 2~

number NAnn of WIMP annihilations in

DM-halo (per unit time/volume):

CMD from NFW profile of the CDM halo

v WIMP velocity profile in the halo

sAnn cross section from theoretical calculations

2

2

2

v~

v~

CDM

CDMAnn

CDMAnnAnn

m

nN

s

s

WIMP annihilation rate in DM halos: GAnn ~ 2CDM

searching in areas with DM overdensities

- galactic centre

- sub-halo centres: dwarf galaxies, …


WIMP-density profile in inner DM-halo strongly model-dependent!

- DMA-signal rates

are model-dependent:

different

parameterisations of

the radial WIMP

halo profile

sightofline

CDMAnn dsN 2~

DMA-sources & halo profile

Moore

Einasto

NFW

isothermal

distance r from galactic centre (kpc)

rsun

DM,sun

DM

de

nsity

D

M(G

eV

/cm

³)


energy-dependent flux FAP,i of WIMP annihilation products (g, n)

is given by the integration along the line-of-sight:

dN/dE: energy spectrum

WIMP annihilation: line-of-sight

Fsightofline

i

CDM

AnniAP dsdE

dN

mE 2

2,4

1v~)(

s

1212

, 106.5),( F scmEiAP

: solid angle

1 pb 1 TeV

small flux of particles from DMA

KIT-IEKP16 Sept. 30, 2015

inte

gra

l alo

ng

line-o

f-sig

ht

angle q

G. Drexlin – DM2

energy-dependent flux FAP,i of WIMP annihilation products (g, n)

is given by the integration along the line-of-sight:

dN/dE: energy spectrum

WIMP annihilation: line-of-sight

Fsightofline

i

CDM

AnniAP dsdE

dN

mE 2

2,4

1v~)(

s

galactic centre d = 7.6 kpc

dominant

source

Andromeda d = 780 kpc

galactic centre

Andromeda

sub-halo

dwarf galaxy

Virgo



b) astrophysical background (sources, background mechanism)

inverse Compton effecthow: energy distribution of background, processes?

where: location of pulsars, SNRs, CR-sources ? background: pulsars, SNR…

e+

g

WIMP annihilation – modelling of background

gamma

high-energy electron

low-energy photon

http://spacefellowship.com/wp-content/uploads/2009/10/397296main_GRB_photon_race_.jpg

http://spacefellowship.com/wp-content/uploads/2009/10/397296main_GRB_photon_race_.jpg


astrophysical background processes for g´s

- are generated by the production and reactions

of the (non-thermal) cosmic radiation

- various galactic sources:

a) SN-shock waves in SNRs (SuperNova Remnant)

b) pulsar winds, ms-pulsars

c) processes in the interstellar medium (ISM),

- extragalactic

a) active galactic nuclei

WIMP annihilation: gamma background

electrons: pulsar wind

protons: SNRSN1006 in g-rays (GeV)


propagation


c) propagation of (anti-)protons & electron/positrons in galactic B-fields

super-bubbles

WIMP annihilation – modelling of transport


propagation

detection


super-bubbles

TeV-gammas

Cherenkov-

showers

telescopes

WIMP annihilation – modelling of detection

d) efficiency of detectors at GeV-TeV scale


DMA – detection: uncertainties

systematic effects from astrophysics & particle physics in detecting DMA:

DM halo profile

(sub-Halos?)

DM propagation

(energy losses, B-fields)

ASTRO SUSY

- background

sources (pulsars,

SNR,…)

WIMP-properties:

- mass

- flavour (B0, W0)

- sAnn ∙v

- decay channels

~ ~


sub-halos sum

G. Drexlin – VL11

modelling of different contributions to DMA signal

WIMP annihilation: modelling of signal

galactic centre WIMP halo


Satellit: Fermi DM annihilation

in galactic centre,

in CDM sub-halos

,...,,,0

1

0

1 ngcc ep

DMA: antiprotons, positrons

e+

ISS: AMS-02p_ antiprotons, positrons:

- deflection in galactic B-field

- energy losses (e+: local origin only)

- rather small backgroud (antiprotons) &

well-defined (e/m) signal

- atmosphere shields p and e+ :

satellites with strong B-field (GeV)


DMA: Gammas

,...,,,0

1

0

1 ngcc ep

g

- point back to their region of origin (source)

- no energy losses (no inelastic scattering)

- no deflection in galactic B-fields

- gamma energies extend up to m(c)

- but: atmosphere shields GeV-TeV g´s:

satellites (GeV) & Cherenkov-telescopes (TeV)

Gamma-rays:

DM annihilation

in galactic centre,

in CDM sub-halosg

upper

atmosphere


DMA: Gammas

galactic centre:

very good statistics

many bright sources

extra-galactic:

good statistics

diffuse background

galactic halo:

good statistics

diffuse background


GeV TeV

galaxis:

38 g/cm2

atmosphere:

1000 g/cm2

DMA: gammas

Vela

DMA?

Geminga

Crab

E > 10 GeV ~500 sources

3C454 3


Fermi-Gamma-Observatory

Fermi key parameters

data taking since mid-2008

altitude 560 km

dimensions 2.8 m(h) × 2.5 m(Ø)

weight 4.3 t

g-energy interval 20 MeV – 300 GeV

effective area 1 m2

angular resolution ~ 1´

Fermi-g-Observatory

- principle: pair conversion

- successor of Compton-GRO

with major improvements:

- larger effective area

- better angular resolution

- higher genergies

LAT


single tower

G. Drexlin – DM2

Fermi – Large Area Telescope LAT

LAT: large area covered solid angle d ~ 20% (at any time)

- 4 coverage every 3 hours

- 16 single towers

g

calorimeter (8.6 L0)

CsJ-crystals

Gamma energy

g-conversion

(16 W-foils)

anti-coincidence

Si-strips

(tracker)

gamma-direction

e-

e+


FERMI – results after 3 years

Vela

Geminga

Crab

3-year data taking with FERMI – galactic chart in multi-GeV gammas

energy spectrum shows no clear hints for DM annihilation

3C454 3

PSR J1836+5925

- ms Pulsare

- g-Pulsare

DMA?

Vela

Geminga

Crab

3C454 3

E > 10 GeV ~500 sources


Fermi – results after 3.7 years

103

102

101

1

Data taking from 8/2008 – 4/2012: gamma map from 2.6 – 541 GeV

- more than 500 point sources eliminated from dat

events

/ 1°×

1°

- definition of ROIs around galactic centre

R3 - 3° / R16 - 6° / R41 - 41°

- Likelihood analyses to search for line sources


- no significant g-line in overall dat-set

- weak hints for g-line at Eg = 133 GeV (most prominent in R3)

- signal also observed (but weaker) in direction of earth horizon!

- actual significance 1.5 – 3.2 s (depends on interval & model)

10 50 100 200 Eg (GeV)

R16-results

(3.7 Jahre)

observedexpected limit

68% CL95% CL

95%

CL lim

it

flux

Fg(c

m-2

s-1

)

10-8

10-9

10-10

Fermi – results after 3.7 years

Data taking from 8/2008 – 4/2012: gamma map from 2.6 – 541 GeV

133

GeV?


Fermi – 2014 update on results

excess of g-events in energy range 1-3 GeV, extending up to 1.5 kpc from GC

- interpreted as decay of WIMP with M = 31-40 GeV → bb quarks

(the „hooperon“: lead author Dan Hooper, Fermilab)



modelling of gamma spectra from 30 GeV WIMP-decays: bb-channel?

Eg (GeV)

0.5 1 2 5 10 20

Mc = 30 GeVE

2g·

dN

g/dE

g(G

eV

)10

7

5

3

2

1

_



Fit to FERMI data by Hooper et al. for galactic NFW profile: a hooperon?

Eg (GeV)

0.5 1 2 5 10 20

E2

g·

dN

g/dE

g(1

0-6

· G

eV

/cm

²/s/s

r) 3

2

1

0

Mc = 35.25 GeV

bb

s·v = 1.0 · 10-26 cm³/s

for local = 0.3 GeV/cm³

_



Fit to FERMI data by Hooper et al. for galactic NFW profile: centered on GC



Fit to FERMI data by Hooper et al. for galactic NFW profile: the parameters

mc (GeV)

15 20 25 30 35 40

s ·

v (

10

-26

· cm

³/s)

3

2

1

0.7

0.5


Fermi – 2014/15 update on results

excess of g-events in energy range 1-3 GeV, extending up to 1.5 kpc from GC

- could also stem from much more massive (200 GeV) neutralinos in MSSM

- annihilation cross section s v = (1.4 – 2.0) ˖ 10-26 cm³ s-1

DMA of hooperon ms-pulsars

2 GeV g

- conventional scenario based on unresolved population of ms-pulsars

(Weniger et al, arxiv:1506.05104)

ms-pulsars emit g´s with Eg ~ 2 GeV, distinct sources give a better fit


Fermi – 2015 results from KIT

DMA of hooperon no excess in de Boer et al.

excess of g-events in energy range 1-3 GeV disappears by proper modelling

- g-excess in galactic plane correlates with regions of Al-26 production (SNR)

- scenario: excess due to „old CRs“ in dense environment of GMCs

Al-26

- hard component with E-2.1 slope from „fresh CRs“ shows same morphology

- conclusion by de Boer /Gebauer: „excess at GC disappears when GMC

with high column density are correctly described“ arXiV:1509.0531 (17.9.15)


WIMP annihilation: IACTs & satellites

MeV/GeV: satellites TeV: IACTs

Fermi

IACT sensitivity is ideal for high g-energies in the multi-TeV-region g

am

ma

flux

(TeV

-1cm

-2s

-1)

gamma energy (TeV)


atmospheric Cherenkov telescopes

ground-based gamma astronomy at TeV-scale with IACTs:

Imaging Atmospheric Cherenkov Telescope

search for TeV-gammas from DMA at galactic centre (GC)

GC

- range of TeV-g´s: ~ 100 Mpc - 1Gpc (o.k. for c0-annihilation)

- telescope operation: only in clear moonless nights (~ 1000 h / year)


~10 km

Ground-based gamma astronomy at TeV-scale with IACTs:

- TeV gammas initiate airshower cascades & generate charged particles

- cascade process: g → e+e- (pair production) → g (bremsstrahlung) → …

- relativistic e+e- emit Cherenkov-photons into a narrow cone (~1°)

reflector area ~ 100 m2

air shower

TeV-gamma ray

0.066 photons

m-2 GeV-1

air shower

TeV-g

atmospheric Cherenkov telescopes


TeV – Gamma-observatoriesVeritas

H.E.S.S.

MAGIC

CANGAROO III

Milagro


H.E.S.S. – galactic centre in TeV gammas

after subtraction of this

source extended regions of

TeV-g-emission are visible:

interactions of CR protons

with giant molecular clouds

HESS observes a clear

TeV gsignal from the

galactic centre Sgr A*


search for mono-energetic DMA-line from 0.5 – 25 TeV in central 1°

around galactic centre (avoiding galactic plane) over t = 112 h

H.E.S.S. – galactic centre in TeV light

gamma energy (TeV)1 10

P(x)

G(x)

MC for 2 TeV g-line DMA

total background

in inner regions @GC

increased g-rate

due to HE cosmic rays

supernova

explosions

activity of

central SMBH

phenomenological

description G(x), P(x)

of g-energy spectrum

no signal


CTA observatory

CTA : world-wide flagship project of TeV gamma astronomy

Cherenkov Telescope Array CTA: (10 GeV – 100 TeV)

- new observatory: 1× southern, 1× northern hemisphere

- more than 100 Cherenkov telescopes of different size

- commissioning and first data-taking ~ 2020, will look for DMA


CTA observatory

search for DMA in

specific target regions:

- galactic centre

- galactic halo

- dwarf spheroidal

galaxies

- diffuse emission

focus on high

energies ~ 1-10 TeV


CTA observatory

search for DMA in

specific target regions:

- galactic centre

- galactic halo

- dwarf spheroidal

galaxies

- diffuse emission

Dark Matter - II - KIT · Fermi –Large Area Telescope LAT ... 3-year data taking with FERMI...

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Transcript of Dark Matter - II - KIT · Fermi –Large Area Telescope LAT ... 3-year data taking with FERMI...