Searches for Dark Matter with GLAST

W. Atwood SCIPP-UCSC / Glast Sci. Lunch 1

GLAST LAT

Searches for Searches for Dark Matter with GLASTDark Matter with GLAST

Gamma-ray Large Area Gamma-ray Large Area Space TelescopeSpace Telescope

Bill AtwoodSCIPP/UCSC

Glast Science Lunch5-Aug-2004


GLAST LAT Road Map for Photons from Dark MatterRoad Map for Photons from Dark Matter

TypeLine

XX , Z0

(Small Br,Line Spectra)

InclusiveXX + Anything

(Large Br,Continuum Spectra)

Particle SourceSUSYX: 0

(LSP - many modelsparameter space large)

LIMPX: Heavy R

(Signal to weak too be observed by GLAST)

WhereGalactic CenterKnown Location

Intensity DependenceDiffuse Character

Extra GalacticAssociated with AGNPoint Like Character

Galactic Center Extra Galactic

Line

Strongest

Location & Energy

Weak

Energy smeared by

red-shift

Inclusive

Difficult to disentangle

Bkg model dependent

Very Hard

Focus on Galactic Center


GLAST LAT

EGRET to GLAST: Galactic Diffuse EGRET to GLAST: Galactic Diffuse ray ray Emission near the GC - PSF is ImportantEmission near the GC - PSF is Important

EGRET

GLAST

GC source in LAT ~ 10 arc-sec location for bright sources


GLAST LAT Gamma Ray Flux From WIMPSGamma Ray Flux From WIMPS

2

2

...

)(

2

1)(

4),(

M

ldlB

dE

dNvE

fsolf

f

The flux of gamma rays from WIMP annihilation has many terms: Cesarini et al, astro-ph/0305075

WIMP Number DensityAnnihilation Cross Section& Thermal Velocity

Branching Fraction& Photon Spectrum

: Angle away from Galactic Center: Line-of-Sight in direction l.o.s

ff

f JBdE

dN

M

GeV

scm

vE )()

50)(

10(1074.3),( 2

132610

Units: cm-2s-1GeV-1sr-1

With: sol

dlGeVcm

l

kpcJ

..

23

)()3.

)((

5.8

1)(

Recasting & Scaling in terms of nominal values


GLAST LAT

0 0.1 0.2 0.3 0.40.1

1

10

100

1 103

r

a2 2 0

r

a1 3 1

r

a2 3 .4

r

a

/ c

Isothermal

Navarro-Frenk-White

Kravtsov et al.

/)())/(1()/(

)()(

arar

rr c

Orders of Magnitude Uncertainty in J()

Density Modelsa = core halo radius / pwr. law break pt. ~ 3 kpc = Cusp. parm. (0= no cusp.) Isothermal profile 2 2 0 Navarro-Frenk-White 1 3 1Moore et al… 1.5 3 1.5Kravtsov et al.(a) 2 3 0.2Kravtsov et al.(b) 2 3 0.4

GLAST Angular Resolutionper Photon ~ .1o

above ~ 10 GeV

GOOD NEWS!Recent evidence from analysis of INTEGRAL data suggests

.4 < < .8Boehm et al, astro-ph/0309686

Phys.Rev.Lett. 92 (2004)

WIMP DensityParameterization

Largest Uncertainty in Predicted RateLargest Uncertainty in Predicted Rate


GLAST LAT Example of Predicted Gamma Ray FluxExample of Predicted Gamma Ray Flux

L. Berstrom, P.Ullio & J.Buckley 1998

1 Photon - 5 year Integrated Glast Sensitivity Limit

GLAST Sensitivity EfficencyFactorSourceOnTAAT Eff

= (.6 x 104) (5yrs x x 107) (.33) (.8)= 2.5 x 1011 cm2-s

Integrated Sensitivity

0

10

00

)1(E

ATE

NATdE

E

NN

00

01

1

EATE

NF LimitPhoton

Setting N =1

Note: Rates could be < 10x Smallerdue to (r)

use = 2.7

dAA EffVOF

Eff..

1where


GLAST LAT Experimental & Interpretation IssuesExperimental & Interpretation Issues

• Wash-up of Low Energy Events to Hi-energy

• Energy Resolution (Line Spectra)

• Astrophysical Source Pollution

• Diffuse Background

Some of what follows are PRELIMINARY Analysesand do not represent either an

Optimal or Final Analysis


GLAST LAT Wash-up of Lower Energy PhotonsWash-up of Lower Energy Photons

Prob > .25Eff = 92%

Prob > .80Eff = 75%

CAL-Hi Total Correction Factor

3.5 GeV < E RECON < 180 GeV-1 < cos() < -.3

Correction to Meas. Energy Leakage Edges

Criteria for quality of energy measurement: Classification Tree based Probability using event specific variables

All Probs.

Larg

e Hi-E

Tai

l

Mod

. Hi-E

Tai

l

Small

Hi-E

Tail

Over

Est.

Evt.

Frac.

>20% 2.3 x 10-2

>30% 5.0 x 10-3

>50% 1.5 x 10-4

Cumulative Error can be largeLow-Energy Hi-Energy

PRELIMINARY!


GLAST LAT Hi - Energy ResolutionHi - Energy Resolution

30 - 100 GeV

100 - 180 GeV

3 - 10 GeV

10 - 30 GeV

E/E

E/E

E/E

E/E

Energy Resolution Integrated over Field-of-View

Present Calc. gives 10% or Better well past 100 GeV

PRELIMINARY!


GLAST LAT Source PolutionSource Polution : Multivariate Analysis : Multivariate Analysis

The task is to take two reconstructed photons and to 1) combine them to make the covariance weight sum (optimal average location) 2) Find the "" for this association

Photon descritpion: 3 parameters - 2 angles and an energy: x = (b, l) & E

Errors on parameters x : C =

Cbb Cbl

Clb Cll

C = <(x-xmc)(x-xmc)T>

<x> = C-1(1)*x(1)+ C-1(2)*x(2)

C-1(1) + C-1(2)

and C(1+2) = (C-1(1) + C-1(2))-1

= (x(1)-<x>)T CRES(1)-1 (x(1)-<x>) + (x(2)-<x>)T CRES(2)-1 (x(2)-<x>)

where CRES(1,2) = C(1,2) - C(1+2)


GLAST LAT FastSim Data

Aeff PSF

A "quick and dirty" source to photons with which to export


GLAST LAT

-.2 < cos() < -.4 -.4 < cos() < -.6

-.6 < cos() < -.8 -.8 < cos() < -1.

FastSim Covariance

Error Ellipses for 1 GeV Photons

LAT orientation held fixed (otherwise all would smear to circular distributions)


GLAST LAT FastSim Data Samples

Mc Truth FastSim


GLAST LAT An Energy Flow StatisticAn Energy Flow Statistic

Algorithm:1) For all photons - find the closest photon (smallest angular separation)2) Form the <x> and for this pair

3) Compute: EFlow = & Log10(EFlow)2

21

EE

10 Source + Diffuse Example


GLAST LAT FastSim Data Samples (2)

Diffuse

800 Sources in 1 str.


GLAST LAT 800 Sources (Closer to Reality!)

Diffuse/Source

Diffuse Efficiency


GLAST LAT Applications

1) Dark Matter signal form Galactic Center (Show that its Diffuse)

2) Large Scale Structure (Bias data to be Sources - Study Sph. Harm.)

3) Extra-Galactic Diffuse (Is there any?)

4) Characterizing Halo's


GLAST LAT Diffuse Background at Galactic CenterDiffuse Background at Galactic Center

A.W.Strong, I.V. Moskalenko, & O. Reimerastro-ph/0406254

Galactic Center Region has excess > GeV 's compared to conventional galactic diffuse model (GALPROP)

7.2

1

E

GALPROP (local CR Spectra) GALPROP (Optimized CR Spectra)

Good News: Diffuse Background small at Hi-Energy

Bad News: Reasonable changes to CR Spectra fit the data well


GLAST LAT LHC SUSY ReachLHC SUSY Reach

Plot courtesy of Abe Seiden from HEPAP presentation, April 2004

LHC is a "SUSY Discovery Machine" Abe Seiden

LHC Turn On – 2007

Covers Most(?) of GLAST Discovery Space in a very short time

Plausible scenario: LHC Discovers SUSY and sets parameters

GLAST Measures the Role it plays in CDM


GLAST LAT Optimism: EGRET Data & SUSY ModelsOptimism: EGRET Data & SUSY Models

GLAST Data PredictionFit to EGRET Data

A.Cesarini, F.Fucito, A.Lionetto, A. Morselli, P.Ullio, astro-ph/0305075


GLAST LAT SummarySummary

• The GLAST-LAT is well along in the build of flight hardware

• Scheduled Launch in 2007

• Adequate Sensitivity for detecting a portion of SUSY Neutralino Models Space

• Detailed event-by-event description will aid in reducing energy

and unresolved-source systematics

• Given current background estimates, may be adequate

to detect line structure

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E

Searches for Dark Matter with GLAST

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