Science Capabilities - Summary

200 bursts per year prompt emission sampled to > 20 µs

AGN flares > 2 mn time profile + E/E physics of jets and

acceleration

bursts delayed emission

all 3EG sources + 80 new in 2 days

periodicity searches (pulsars & X-ray binaries)

pulsar beam & emission vs. luminosity, age, B

104 sources in 1-yr survey AGN: logN-logS, duty cycle,

emission vs. type, redshift, aspect angle

extragalactic background light ( + IR-opt)

new sources (µQSO,external galaxies,clusters)

1 yr catalog

100 s

1 orbit

1 day

LAT 1 yr2.3 10-9 cm-2 s-1

3EG limit

0.01

0.001

Active Galactic Nuclei - Cosmic Linear Accelerator -

• Synchrotron and inverse Compton radaition emitted by ultra –relativistic flow of electron-positron plasma along the axis of the distant rotating super-massive black hole (Quasar: PKS 0637-752)

Active Galactic Nuclei: New Way to Study

• Measure the spectra above 100 MeV from AGN (based on blazar logN-logS extrapolations)

• Explore low-energy spectrum where many AGN have peak emission

• Monitor variability and notify flares

• Study of AGN evolution and history of star-forming activity

• Overlap with ground-based gamma-ray observations

Study of time correlation

Btwn X-ray and -ray.

Active Galactic Nuclei: Time Variability

GLAST monitors all-sky continuously with high sensitivity, detects many AGN flare-ups before anyone else, and records their entire history for the first time.

Active Galactic Nuclei: Spectrum GLAST will detect ~3000 AGNs, reaching to z~4-5. Thus we will detect cosmological

evolution of AGNs and their role in the galaxy formation. Extragalactic IR-UV

background light (EBL) by star-forming activity absorbs high energy gamma-

rays by > e+e-. Thus GLAST will measure history of star-formation in z~1-5.

Accelerating Shock Fronts- Cosmic Random Phase Synchrotron -

Super Nova Remnant 1006 seen by ASCA (X-ray band)

Image of synchrotron radiation by high energy (~200TeV) electrons in the

accelerating shock front in SN1006

Accelerating Shock Fronts- Cosmic Random Phase Synchrotron -

Super Nova Remnant 1006 seen by Cangaroo (TeV gamma-ray) Image of photons (CMB) scattered by high energy (~200TeV) electrons

in the accelerating shock front of SN1006.

Pulsars (Rotating Neutron Stars)- Cosmic Betatron -

• Synchrotron emission (X-ray) by high energy electrons (~100GeV) from the neutron star’s magnetosphere (Magnetic induction: Pulsed)

• Synchrotron emission (X-ray) by high energy electrons (~100TeV) from the nebula around the neutron star’s magnetosphere (Accelerating shock front: Unpulsed)

The bell-shaped synchrotron nebula around the Crab pulsar (the small dot at the center of the opening of the bell-shaped nebula). A string-like flow of electrons along its rotation axis is also visible.

Pulsars: Radio-Quite Brothers (NS)• Until recently, all pulsars have been discovered in Radio Band, with one exception of

Geminga.

• In the past 5 years several pulsars have been discovered in X-ray. They are generally very weak in Radio Band. Many radio-quiet pulsars to be discovered

• We now expect to find many radio-quiet pulsars. We can see throught the Galaxy with gamma-rays but not with radio wave. So we will study distribution of pulsars (ie. NS’s) in the Galaxy. History of star-formation activity in our Galaxy.

Geminga’s pulse profile by EGRET

GLASTRadio-quiet

Radio-loud

Gamma-ray BurstsLAT:

– Capture > 25% of GRBs in LAT FOV (2 sr or more)– Deadtime of < 100 msec per event– Spectral resolution < 20%, especially at energies above 1 GeV

GBM:– Monitor energy range: 10 keV - 20 MeV– Monitor FOV of 8 sr (shall overlap

that of the LAT)– Notify observers world-wide:

• Recognize bursts in realtime• Determine burst positions to few degree

accuracy• Transmit (within seconds) GRB

coordinates to the ground• Re-point the main instrument to GRB

positions within 10 minutes

Gamma-Ray Bursts: Wide Energy Coverage

10 keV 10 GeV10 MeV

•Cover the classical gamma-ray band where most of the burst photons are emitted by GLAST Gamma-ray Burst Monitor (GBM)•Monitor all of the sky visible from Low-Earth Orbit ( 10keV-30MeV)•Monitor 40% of the sky visible from LEO (20MeV-500GeV)•Identify when and where to re-point the spacecraft to optimize observations and notify other observers

Simulation: Spectrum of an intense GRB by GLAST

Gamma-Ray Bursts at > 20 MeV

• EGRET discovered high energy GRB afterglow

– only one burst

– dead time limited observations

• GLAST will observe many more high energy afterglows

– strong constraint to GRB models

Gamma-Ray Bursts at > 20 MeV

Spatial:

• Monitor > 2 sr of the sky at all times

• Localize sources to with > 100 photons to < 10 arcmin

Temporal:

• Perform broad band spectral studies and search for spectral structure

• Find correlation between 10 keV - 20 MeV and > 20 MeV photons

• Determine characteristics of > 20 MeV afterglow

Gamma-Ray Bursts: Correlation btwn X-ray and -ray

Standard wisdom about GRB is: the more energetic, the closer to the central energy source.GLAST measures both in X-ray/soft -ray (GBM) and high energy -ray (LAT), arrowing tostudy temporal correlation between them.

Cosmic Ray Interaction with Inster Stellar Matter (1)

Inner Galaxy (|l|<60o,|b|<10o)by EGRET. Elect. Brems., Inv. Compton, Isotr. Diff., and N-N int. (pi-zero).

SNR IC443 by EGRET andGLAST (simulation).Elect. Brems., Inv. Compton, and N-N int. (pi-zero).Note that electron contri. dominates in SNRs.

Cosmic-Ray Flux and Composition

in SNRs, GMCs, Galactic Plane/Bulge, Nearby galaxies, Nearby Clusters

Separation of electron contribution (brems. and IC) and proton contribution (pi-0)is important. Association of SNRs, history of the galaxy or the cluster

Even in galactic level, the total energy of cosmic-ray is non-negligible. It can be very important in cluster level.

Cosmic Ray Interaction with Inster Stellar Matter (2)

Radio image of Molecular H line(21cm)

EGRET image GLAST image(simulation)

Gamma Cygni SNR: Pulsar, SNR, and cosmic-ray interaction with ISM

Measurement on cosmic-ray proton and electron fluxes

Cosmic Ray Contents in Nearby Galaxies

LMC by EGRET

LMC by GLAST(simulation)

LMC in IR (IRAS)

GLAST will measure cosmic electron and proton fluxes for LMC, SMC and M31

Past SN rate, past history of galaxies, stability of galaxies

Galactic Diffuse Emission: Galaxy Simulator Project• Objectives

– Separate pi-zero and electron brems. contributions

– Determine total mass of nearby GMCs C/H ratio

– Galactic electron distribution SNR association?

– Galactic arm structure What are between arms?

– Correlation with radio, X & hard-X observations

– Galactic magnetic field: strength and large scale structure

– Determine total amount of cold dark baryonic matter

Giant Molecular Cloudsin Cygns region(galactic arm structure?)

Pi-zero flux measurement by GLAST will determine the total mass in the GMCs and their C/H.

Schedule of the GLAST Mission

2000 2001 2002 2003 2004 2005 2010

Formulation Implementation

SRR NAR M-CDR PDR I-CDR Inst. Delivery Launch

Build & TestEngineering Models

Build & TestFlight Units

Inst.I&T

ScheduleReserve

Inst.-S/CI&T

Ops.

Calendar Years

Thank you for attention. Please wait for launch in

2005