Jacques Paul

Jacques Paul

Soft Gamma-Ray AstronomySoft Gamma-Ray Astronomy

23 January2001

Rencontres de MoriondLes Arcs

Expected Impact on VHE PhenomenaExpected Impact on VHE PhenomenaPanorama in the Coming YearsPanorama in the Coming Years

INTEGRAL Mission Scientist

CEA/DSM/DAPNIA/Service d'AstrophysiqueCEA-Saclay, France

ForewordForeword

Jacques Paul Rencontres de Moriond23 January 2001

Contrarily to the great majority of celestial bodies which radiate mostly in a narrow spectral band (thermal emission), cosmic sites of high-energy phenomena generate non-thermal radiation in a wide spectral domain.

Cosmic sites of high-energy phenomena should then be observed not only in the very high-energy photon band but also over a very large spectral domain.

Simultaneous observations performed in both X-ray and gamma-ray spectral domains remain however the privileged means – sometimes the only one – to study the profound mechanisms of cosmic high-energy phenomena.

Extreme sources active in the soft-gamma ray band

Major points of the presentation

Observational status in the soft-gamma ray band

Because of the huge amount of mechanical energy released by SN explosions (~ 1051 ergs), it has long been thought that shock waves induced by supernova explosions are responsible for the acceleration of cosmic rays up to energies ~ 100 TeV. Observational clues?

Supernova RemnantsSupernova Remnants

SN 10060.4-8 keV composite ASCA image

Brightest X-ray zones of SN 1006 feature non-thermal spectra. Likely origin: synchrotron emission of relativistic e- up to ~ 100 TeV in a ~ 10-5 G magnetic field. In agreement with TeV gamma-ray observations.

Primordial role of SNR observations in the hard X rays / soft gamma rays to characterize non-thermal emission.


PulsarsPulsars

The wind of relativistic electrons released by the pulsar produces a strong relativistic shock when interacting with the surrounding medium site of particle re- acceleration up to 1015 eV.

The magnetosphere of a pulsar (highly magnetized neutron star) includes efficient sites of electron acceleration taking advantage of the neutron star spinning down.

X-ray image (Chandra)

Crab pulsar

Acceleration sites


MicroquasarsMicroquasars

0 3564

0

4

1E 1740.7-2942

Galactic longitude

Ga

lact

ic la

titu

de


SIGMA image of the central region of the Galaxy recorded in the 75-150 keV band. Bright sources are accreting stellar mass black holes.

Radio observations of the source 1E 1740.7-2942 have revealed that accreting black holes can generate powerful bipolar jets of relativistic particles microquasars.

Plasma moving close to the light velocity

Strong radio emission

Jet of subatomic particlesHard X rays

Jacques Paul Rencontres de Moriond

23 January 2001

Gamma-Ray Bursts Gamma-Ray Bursts

An initial event leads to a stellar BH surrounded by a thick debris torus. A fraction of the energy from the disk and/or the rotating BH is injected into a relativistic wind. Internal relativistic shocks are produced when a “rapid” wind layer catches up with a slower one. Gamma rays are radiated by highly relativistic electrons accelerated behind the shocks simultaneous low-energy / high energy observations.

1. BH disk system

3. Internal shocks

2. Relativistic wind (Γ > 100)

BeppoSAX

CAT

BlazarsBlazars

16/04

07/04

Mrk 501 April 1997

Jet models, such as the synchrotron-self-Compton process, require Compton scattering of soft photons by relativistic electrons in the jet. The low-energy photons can originate as synchrotron emission from within the jet simultaneous low-energy / high energy observations.


Observation Status (50 keV-5 MeV)Observation Status (50 keV-5 MeV)

PAST

CGRO (including the three low-energy gamma-ray detectors OSSE, BATSE and COMPTEL) has been de-orbited on June 3rd, 2000, because of failure of gyro # 3.


PRESENT

BeppoSAX to stop soon because of financial issues...

HETE-2 to operate up to 2003.

FUTURE

INTEGRAL to be launched in 2002. Lifetime: 5 years.

AGILE to be launched in 2002. Lifetime: 2 years.

SWIFT to be launched in 2003. Lifetime: 2-3 years.

Gamma-Ray Burst MissionsGamma-Ray Burst Missions

HETE-2

Non imaging 6-400 keV GRB monitor, 2-25 keV and 0.5-14 keV X-ray wide field cameras. Was successfully launched in October 2000.

SWIFT

Imaging 10-150 keV GRB detector (GRB location < 4’). Survey of the GRB field in X-ray (0.2-10 keV) and UV-visible (170-650 nm) bands. To be launched in 2003.


Spectrometer SPI

Imager IBIS

TheThe INTEGRAL INTEGRAL MissionMission

Spectroscopy and imaging of sources in the 15 keV-10 MeV band with source monitoring in the X-ray (3-35 keV) and visible (550 nm) bands. Worldwide collaboration including ESA (satellite), European scientific institutes (payload), Russia (launcher) and US (TM station).


To be launched on April 22, 2002, from Baikonur by a Proton rocket.

Coded Mask Telescope: It Works !Coded Mask Telescope: It Works !Crab Nebula the standard

calibration source for

gamma-ray astronomy

SIGMA, first coded-mask telescope to

operate in the 30-1300

keV band

Sky image built in the 40-75 keV band with a 13’ angular resolution

Raw image recorded by the SIGMA position sensitive detector

Observation Déconvolution


The Imaging Telescope IBISThe Imaging Telescope IBISDistinct detection layers located 3.2 m below a coded mask.

ISGRI, an array of 16384 CdTe pixels.

PICsIT, an array of 4096 CsI pixels.

Both detectors shielded by BGO scintillators.

Energy range 20 keV-10 MeVField of view 9° x 9° (fully coded)

Source location determination < 1’Energy resolution 7% at 100 keV

100 keV sensitivity (3,106 s) 4 10-7 photon cm-2 s-1 keV-1


A polycell

First light

The IBIS Upper Detector PlaneThe IBIS Upper Detector Plane

One of the eight modules of the IBIS low energy detector plane, made of 128 polycells, each being an array of 4 x 4 CdTe semi-conductors.


IBIS Continuum SensitivityIBIS Continuum Sensitivity10-5

10-6

10-7

10-8

10-9

100 1000

Energy (keV)

10000

3σ, 106 s, ΔE = E

Se

nsiti

vity

(p

hot

on

cm

-2 s

-1 k

eV

-1)


Observing ProgramObserving Program

Obs

ervi

ng t

ime

0%

100%

50%

Com

mis

sion

ing

phas

e (2

mon

ths)

Open time (65%) Open time (70%) 75%

Core program (35%) Core program (30%) 25%

Launch Nominal Mission Phase ExtendedPhase

12 months 36 m12 months


Access to Access to INTEGRALINTEGRAL

INTEGRAL is a real observatory, fully open to a very wide Scientific Community of astronomers, particle physicists, nuclear physicists…

In spite of the special nature of the scientific devices (coded aperture), non-specialists should have an easy access to the physical parameters of the target sources.

The Announcement of Opportunity includes necessary tools and documentation to allow non-specialists to prepare competitive proposals.

Proposal material available via the Internet at:http://astro.estec.esa.nl/Integral/isoc


AO-1 has been released last November and the due date for proposals is 16 February 2001 (14h GMT).

Jacques Paul

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