1. GeV Gamma-ray Astronomy with GLAST

2. Outline GLAST Instruments Overview GeV Gamma-ray Science with GLAST
TeV charged particle to produce GeV gamma-rays.
Particle acceleration: origin of cosmic rays?
Gamma-ray emission mechanisms.
AGN
GRB
SNR
Galaxy clusters
Gamma-ray emission from WIMP interactions.
GLAST Status
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

3. GLAST LAT Collaboration
France
IN2P3, CEA/Saclay
Italy
INFN, ASI
Japan
Hiroshima University
ISAS, RIKEN
United States
California State University at Sonoma
University of California at Santa Cruz - SCIPP
Goddard Space Flight Center – Lab. for High Energy Astrophysics
Naval Research Laboratory
Ohio State University
Stanford University (SLAC and HEPL/Physics)
University of Washington
Washington University, St. Louis
Sweden
Royal Institute of Technology (KTH)
Stockholm University
Principal Investigator:
Peter Michelson (Stanford & SLAC)
~225 Members
(~80 Affiliated Scientists, 23 Postdocs,
and 32 Graduate Students)
All countries are still alive at World Cup™ soccer (as of 6/21)
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

4. GLAST LAT Instrument g e- e+ Tracker: conversion, tracking.
Angular resolution is dominated by scattering.
Converter thickness optimization.
Calorimeter: energy measurement.
8.4 radiation length.
Use shower development to compensate for the leak.
Anti-coincidence detector:
Efficiency > 99.97%.
Si Tracker
90 m2 , 228 µm pitch
~0.9 million channels g e- e+
Anti-coincidence Detector
Segmented scintillator tiles
99.97% efficiency
CsI Calorimeter
8.4 radiation length
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

5. GLAST/LAT Performance
PSF
Energy Resolution: ~10% (~5% off-axis)
PSF (68%) at 100 MeV ~ 5o
PSF (68%) at 10 GeV ~ 0.1o
Field Of View: 2.4 sr
Point Source sens. (>100 MeV): 3x10-9 cm-2 s-1 (>30 times better than EGRET)
Dead time: < 30 µs
Thin
Thick
EGRET
Effective area
Thin
converters
(3%)
Thick
(18%) No
FOV
Thin
Thick
Full Tkr
EGRET
EGRET
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

6. Active Galactic Nuclei (Blazar)
(Buckley, Science, 1998)
AGN Science Key Issues.
Energetics of the source
Jet formation and collimation
Particle acceleration
Photon emission processes
Leptonic
Synchrotron self Compton
External Compton
Hadronic
Proton-induced cascades (pp→π0→γγ)
Proton Synchrotron
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

7. AGN Variability Studies
Size and location of the -ray emission region
Connection to BH, accretion disk
GLAST play key role.
All sky survey.
Large FOV
Large effective area
Trigger simultaneous multi-wavelength observation.
Shorter time scale.
PKS
1996 EGRET flare
GLAST simulation
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

8. AGN Population Studies
EGRET
Pointing
GLAST/LAT
All sky
EGRET detected 70–90 AGNs.
GLAST will find thousands of AGNs.
More diversity than EGRET.
Blazar sequence.
AGN evolution.
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

9. AGN as Cosmological Candle
Use thousands of AGNs found by GLAST as cosmological probes.
-rays can be absorbed by interactions with background photons.
GeV photons sensitive to intergalactic UV photons.
Strong dependence on the distance from the source.
History of star formation, large scale structure of universe.
No EBL
Salamon & Stecker
Primack & Bullock
Chen, Reyes & Ritz APJ (2004)
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006
Chen, Reyes, and Ritz, ApJ 2004

10. Gamma Ray Bursts Gamma-ray Bursts. Key Questions.
Cosmological distance
Relativistic beaming
Supernovae connection
2 or more types?
Key Questions.
Origin?
Hypernovae (long GRB)
Binary system merger (short GRB)
Jet formation
Particle acceleration
Photon emission mechanism
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

11. GBM and LAT for GRB Observation
Huge field of view (8sr)
Measure spectra for bursts from 10 keV to 25 MeV
LAT
Wide field of view (>2sr)
Extends spectral coverage to higher energies
GLAST can be re-pointed to catch exceptionally bright bursts that occur outside the LAT FOV.
BGO
NaI
Broadband observation by GLAST.
6 order of magnitude.
-ray emission mechanisms.
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

12. GRB Delayed Gamma-ray Emission
Gonzalez, Nature , 749
Delayed gamma-ray emission from GRB is observed by EGRET.
It is hard to explain by conventional electron synchrotron models.
Proton acceleration?
More samples required to understand further.
Systematic analysis of EGRET data in progress.
GLAST will add much more samples.
GLAST extend the energy reach to ~200 GeV.
Broadband spectra constrain emission models. s
EGRET/TASC
BATSE s s s
Total
Absorption
Shower
Counter s
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

13. TeV Gamma-ray from SNR HESS TeV gamma-ray observation of RX J1713-3946
Evidence for particle acceleration > 100 TeV.
Azimuth profile does not match very well with molecular clouds.
Detailed 3D molecular cloud map
Angular distribution from new particle interaction model.
Aharonian et al. 2005
HESS/ASCA
Aharonian et al. 2005
TeV gamma-ray
Molecular clouds
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

14. Gamma-ray Spectrum for RX J1713
HESS spectrum may prefer hadronic origin.
Not conclusive.
GLAST can positively identify hadronic contribution.
Gamm-rays from π0 decays due to hadronic interaction with molecular clouds.
Berezhko 2006 & Aharonian et al. 2005
Bd = 126 µG
Kep = 10-4
ESN = 1.8 x1051 erg
age = 1600 year
GLAST
Model independent
(π0 production and decay kinematics)
— pp→π0→,
— Inverse Compton (B=9µG)
— Inverse Compton (B=7µG)
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

15. TeV Gamma-ray SNR Candidates
25% Crab
19% Crab
5% Crab
6% Crab
8% Crab
13% Crab
HESS ApJ 636 (2006) 777
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

16. -rays from Merging Galaxy Cluster
Strong shock due minor merger of galaxy clusters.
Model parameters are tuned to be consistent with existing measurements.
Particle acceleration up to 1019 eV. (Origin of UHE-CR?)
Secondary e+e- following proton interaction with CMB photon are dominant origin of gamma-rays.
Inoue 2005 ApJ 628, L9
GLAST
GLAST can detect IC
from secondary e+e-
merging galaxy group
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

17. Merging Galaxy Clusters
Large scale shock by merging galaxy clusters.
Origin of Ultra High Energy Cosmic-ray (UHECR)?
XMM temperature map (U.G. Briel et al)
Abell 3667
Turbulent gas flow
Radio emission: Remnant of large scale (>1 Mpc) particle acceleration site
X-ray surface brightness
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

18. Dark Matter Search with GLAST
Neutralino can be a good dark matter candidate if its mass is in Electro-Weak scale (~100 GeV).
GLAST can be sensitive to the photons from neutralino annihilations. q c c g
Continuum energy spectrum from π0 decays.
Higher statistics…
but higher background
knowledge of galactic diffuse background is critical
Distinct signature
A “peak” in the energy spectrum !!
Lower background…
but lower statistics too
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

19. Dark Matter Search around GC
EGRET data shows a hint of neutralino signal around Galactic center.
Improved angular/energy resolution, sensitivity and wider energy coverage by GLAST may reveal neutralino signal at Galactic center.
Precise measurement of energy cut-off provide definitive signal ofparticle dark matter and its mass.
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

20. Observable Dark Matter Satellite?
Molecular cloud spectrum
Dark matter spectrum
Diffuse background
GLAST
High Galactic latitude
Lower backgrounds.
A few clumps may be observable.
LSP WIMP (SUSY)
GLAST 5-yrs
LCC2
LCC4
Wai
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

21. System Commissioning/ System Test
LAT Test Status
System Commissioning/ System Test
5/11/06
Shipment
5 days
5/16/06
You Are Here
Install Radiators
Offload &
Set-up LAT
CPT
Sine Vibe
EMI/EMC Test
Acoustic Test
5 days
5 days
9 days
11 days
7 days
2 days
PER 5/25/06
7/10/06
Remove
Radiators
Pre TV
T- Bal
T- Cycle
CPT
Weight & CG
Pack and Ship
8 days
3 days
2 days
2 days
2 days
9/15/06
40 days
PSR 9/13/06
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

22. LAT Before Installing the ACD
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

23. LAT on Shipping Container Base
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

24. LAT Data from Tests at SLAC
From A. Borgland
Muon candidates
Most of the 500 Hz of triggers recorded are muons
Photon Candidates
~20% of cosmic ray showers are not muons
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

25. Data Challenges Data Challenges
Originated from particle physics experiment at SLAC (1980’s)
End-to-end test of the data analysis system
Full detector simulation and reconstruction
Two months with celestial sources and instrument backgrounds.
Transient sources.
Merging HEP software and Astro FTOOLS
“Blind “ Analysis
Details of physics not revealed to the collaboration until closeout
Engage the collaboration
to start thinking science
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

26. Summary GLAST will address questions on the origin of gamma-rays.
Observation of thousands of AGNs and hundreds of GRBs.
Models of particle acceleration and -ray emission.
Conclusive proof on the origin of gamma-rays from SNR, RX J
More TeV SNRs will be observed by GLAST.
Constraints on models of particle acceleration in merging galaxies and galaxy clusters.
Severe constraints on particle dark matter models.
GLAST is on schedule for September 2007 launch.
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

27. More DC2 Slides H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

28. Pulsars Goal: blind periodicity searches on candidate DC2 pulsars
Goal: Pulsar population studies: the ratio of radio-loud to radio-quiet pulsars.
Marcus Ziegler – lightcurves of pulsars withut radio data.
Epoch_MET =
F0=
F1= e-012
F2= e-021
Epoch_MET =
F0 =
F1 = e-013
F2 = e-022
Epoch_MET =
F0 =
F1 = e-013
F2 = e-021
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

29. Source detection algorithms
Requirement: That these algorithms are tested and compared with one another in a systematic way using the DC2 data.
Many source detection methods developed – Stephens, Tosti, Burnett, Casandjian, Ballet, Romeo/Cillis
Compared with one another by Seth Digel
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

30. Gamma-ray bursts
This was one of the “rejected” fits due to the strange spectrum. The cause is likely to be because this GRB was simulated with an additional “hard” extended component lasting for 400s.
GRB – Nukri Komin
132 generated in 4p
64 bursts seen in GBM
25 in LAT; 16 with > 4 g
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

31. Spectral Studies
Goal: Study spectra of pulsars to determine the shape of spectral cutoffs
Goal: EBL attenuation studies (redshift dependent cutoffs)
Goal: Search for spectral signatures of dark matter
Luis Reyes
residual
background
bright blazar
(BPL+EBL)
Jennifer Carson
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

32. Variable Sources flux (1day bin) flux (8h bin)
Gino Tosti – Taking lightcurves to the next level…
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

33. Image Deconvolution for Diffuse
Poor GLAST PSF make it difficult to resolve RX J
Model independent image deconvolution required.
Image deconvolution is essential for extended sources.
Galactic diffuse, dark matter search, galaxy clusters.
Deconvolved image gives better representation of input image.
Overall shape recovered.
Toy MC demonstration
GLAST 3.2x1011 s•cm2 observation
@ erg/cm2/s, ∝E-2, E > 1GeV, PSF = 2.5–27’
Generated image for RX J
After smearing by PSF
After deconvolution
GLAST PSF
@1 GeV
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

34. Demonstration with Realistic MC
GLAST Data Challenge II
More realistic Monte Carlo with full detector simulation and reconstruction for 2 months observation.
Event-by-event PSF with tail.
Depends on energy and incident angle.
Before deconvolution
After deconvolution
Input Vela Jr. profile
Strong point source can be removed cleanly to observe faint extended sources.
(263.55, -2.80)
(263.55, -2.79): Vela Pulsar
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006

35. RX J1713 in DC2 Sample (347.86, 0.51) (347.86, 0.51): Pulsar
Before deconvolution
After deconvolution
Generated
RX-J1713 profile
H. Tajima, GeV Gamma-ray Astronomy with GLAST
High Energy Astrophysics in the Next decade, JUN 21-23, 2006