Transcript Slide 1

Prospects for the Search for Dark
Matter with Fermi
Brian L. Winer
The Ohio State University
Fermi LAT Dark Matter and
New Physics Working Group
Novel Searches for Dark Matter with Neutrino Telescopes
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space
CCAPP DMNov
Workshop
Pageth,1
Center for Cosmology
andTelescope
Astroparticle Physics
17-18




Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 2
WIMP annihilation: gamma-ray yield
WIMP pair annihilation
gamma spectrum
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
200GeV
mass WIMP
CCAPP DM Workshop Page 3
Dark Matter in the gamma ray sky
Milky Way Halo simulated by Taylor & Babul (2005)
All-sky map of DM gamma ray emission (Baltz 2006)
Galactic center
Milky Way halo
Milky Way satellites
sub haloes/clumps
Extragalactic
Only dm annihilation radiation shown….
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 4
Several Different Search Modes
Search Technique
advantages
challenges
Galactic
center
Good
Statistics
Source
confusion/Diffuse
background
Satellites,
subhalos
Point sources
Low
background,
Good source id
Low statistics
Milky Way
halo
Large
statistics
Galactic diffuse
background
Extragalactic
Large
Statistics
Astrophysics,
galactic diffuse
background
Spectral lines
No astrophysical
uncertainties, good
source id
Low statistics
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 5
Background to all photons:
Charged Particles
-Rejection power:
~105-6
-γ efficiency:
~0.8
Total
GCR protons
GCR He
GCR electrons
albedo protons,pbar
albedo positrons
albedo electrons
albedo gammas.
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 6
Galactic Center


Advantage: Largest Source
of DM Photons
Problems:
Astrophysical Sources
 CR Accelarators
 High Energy Gamma Sources

 Behavior at Fermi Energies??

Initial Sensitivity Estimation
ROI = 0.5 deg of GC, E > 1 GeV
 Truncated NFW Profile.
 Simulate Particle-yield (DarkSUSY)
 Background:

Consider Annihilations:
bb tt
 Astrophysical Sources Subtracted

W W

 


(Done Individually)
 GALPROP Represents Diffuse Background

Simulate Detector Response.
Brian L. Winer, Ohio State University

Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 7
Dark Matter From the Galactic Center
 2 for Test Statistic.
Simple
(More sophisticated TS
under study)
5 Years of Sky-Survey

- tt similar
- WW less sensitivity
 
-   more sensitive.

5 Years of Sky-Survey

Current Efforts:
Optimize ROI (Plot)
 Understand Source Removal

 Need data.

Optimize TS.
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 8
Galactic Halo Analysis

Advantage:


Challenge:


Use the large statistics of the full sky.
Critically Dependent on Diffuse Background
Measure the sensitivity
to observing a signal.
ROI = R>10o or |b|>10o
 NFW Profile.
 Diffuse Background:


GALPROP (Conv., Opt.)
Simultaneous Fit to both
spatial and energy
distributions
 Mass vs <s v>
 1 year of running

Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 9
Galactic diffuse: conventional and
optimized GALPROP model

’conventional’ GALPROP:


calibrated with locally measured electron and
proton,helium spectra, as well as synchrotron emission
Optimized GALPROP:
Conventional
Optimized
Strong, Moskalenko, Reimer,
Strong, Moskalenko, Reimer,
ApJ 537, 736, 2000
ApJ 613, 962-976, 2004
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 10
Galactic Diffuse Background:
Brem
E 100 MeV
b

l
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 11
Galactic Diffuse Background:
Neutral Pion Decay
E 100 MeV

b
l
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 12
Galactic Diffuse Background:
Inverse Compton
E 100 MeV

b
l
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 13
Galactic Diffuse Background:
Total
E 100 MeV

b 10o
b

l
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 14
Galactic Halo Analysis

Advantage:


Challenge:


Use the large statistics of the full sky.
Critically Dependent on Diffuse Background
Measure the sensitivity
to observing a signal.
ROI = R>10o or |b|>10o
 NFW Profile.
 Diffuse Background:


GALPROP (Conv., Opt.)
Simultaneous Fit to both
spatial and energy
distributions
 Mass vs <s v>
 1 year of running

Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 15
Sensitivity for Galactic Halo Analysis
Conventional Diffuse
50
Optimized Diffuse
250
50
250
Typical DM Photon Yields (1 year) :
1.5 x 104 (100 GeV/c2)
3 x 103 (250 GeV/c2)
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 16
Halo Analysis: Mass Resolution
100
For cases where we
observer a signal at 5s,
we can determine our
mass resolution.
Warning: Statistical Uncertainty
ONLY…think of this as a “best case/Lower
Limit”
Error bars represent
the 68% CI
Current Efforts:
Work on understanding
Diffuse Background. 0
100
 Optimize ROI
 Understand Source Removal
 Optimize Fitting.
 SYSTEMATICS! SYSTEMATICS!

Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
250
CCAPP DM Workshop Page 17


Search for Sub-halos


In CDM Paradigm, expect MW to
contain potentially large number of
sub-halos.
Sensitivity:

8.9 kpc
2.7107 Mo
b= 39

Assumes Taylor&Babul (05) Distribution
 Sub-halo with Truncated NFW Profile
 MWIMP=100 GeV


s  v  2.31026 cm3s1
bb Annihilation

Background: Extragalactic,
Galactic Diffuse (GALPROP)
 Search for Msub>106 MO.
 Test Statistic:
lnLs  b  lnL(b)
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 18
Sub-halos
Most Sub-Halos are found a
high (|b|) galactic latitude.
Green: GALPOP optimized
Red: GALPROP conventional
99% CL
90% CL
68% CL
No. of satellites
<σannihv > * Astrophy Unc.
Once found an attempt can be
made to extract the DM
parameters. Below are the
error ellipses for the case on
the previous page.
Significance [ σ]
WIMP mass [GeV]
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 19
Dwarf Spheroidal Galaxies

Advantage:





Could be DM Dominated
Assumes 5 years of observations.
Disadvantage:
 DM Profile?
Initial Sensitivity


Sagittarius Dwarf
GALPROP used for
Diffuse
Test Statistic:
2
 Simple: 
 Recent: Likelihood
Likelihood TS:
Sensitivity
Improves by
2-4x
If NFW Profile, sens a
factor 
of 10 less.
Other dSph (e.g. Draco)
will also be studied.
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 20
Line Search

Advantage: ”Smoking Gun”


Simulated
detector response
to δ function in
energy
Backgrounds from data
Challenges:
Some recent
models predict
enhancements.
Small BR <10-3
 Energy Resolution.


Initial Sensitivity Estimation

ROI = Broken Annulus
Proposed by
Stoehr, et al
|b|>15o
 20o < R < 35o ;
 DM Den High but reduced
background




Example MC Sim.
Scan through energy range
Fit Background to exponential
Signal Fit Double Gaussian
Test Statistic:
2
2
 2  min
(s  b)  min
(b)
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 21
Line 5σ sensitivity
5 Years of
Fermi Data
Trials factor
included for
unknown
source.
Current Efforts:


Improved event selection and
energy reconstruction.
Optimized ROI
 Need data  Measure Diffuse Bkg.

Brian L. Winer, Ohio State University
Optimize TS.
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 22
Summary

Fermi has many targets for
the indirect DM search.




Efforts are on-going to
optimize these searches.


Some are statistics limited.
Some are sys. limited
Other Modes:
 Cosmological WIMPS
 Extra Dim: KK  HE Electrons
Real Data Helps!
The DM Working Group plans
an intense effort in the first
year of operation.

We are happy finally to be in
orbit!
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 23
WIMP annihilation: gamma-ray flux
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 24
Acknowledgements
Pre-launch Estimates for GLAST Sensitivity to Dark Matter Annihilation Signals
E. A. Baltz, et al JCAP, 07 (2008) 013, arXiv: 0806.2911v2












E Baltz, B. Berenji, E. Bloom, J. Chiang, Y. Edmonds, G. Godfrey,
P. Wang, L. Wai, J. Cohen-Tanugi(SLAC/KIPAC)
I. Moskalenko (Stanford)
A. Morselli, A. Lionetto (INFN Roma/Tor Vergata)
E. Nuss
(Montpellier)
R. Hughes, A. Sander, P. Smith, B. Winer (Ohio State)
L. Bergström, T. Bringmann, J. Conrad, J. Edsjö, A. Sellerholm
(Stockholm)
A. Moiseev (Goddard)
G. Bertone (Paris)
R. Johnson(Santa Cruz)
J. Ormes (Denver)
R. Rando (Padova)
A. Strong (Max-Planck)
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 25
Parameter Space
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 26
Cosmological WIMPS
Brian L. Winer, Ohio State University
Fermi Gamma-Ray Space Telescope
CCAPP DM Workshop Page 27