POLARIZATION MEASUREMENTS FOR GRBs. Content 1. Introduction: processes of gamma-ray generation 2. Astrophysical sources (BBH, NS&magnetars, AGN, GRBs

POLARIZATION MEASUREMENTS FOR GRBs

Content

1. Introduction: processes of gamma-ray generation2. Astrophysical sources (BBH, NS&magnetars, AGN, GRBs etc)3. Polarimetry technique and instruments4. Wide-field gamma-ray telescope for polarisation measurements.

E HEe2

E E0Ee2

bremstrahlung Synchrotron radiation

Compton scatteringElectron-positron annihilation

p + 3He + n + p.

n + p 2D + (2.23 МэВ).

Pion production in proton-antiproton annihilation

Nuclei excitation by the collisions with fast neutrons

Nuclei excitation

Neutral pion decay

Non-linear Electrodynamics effects in vicinity of pulsars and magnetars

Electrodynamics in vacuum in very strong fields is really

non linear

The typical magnetic field value

Bq = m2c3/e = 4.41 1013 Gs

Gamma-Ray pulsar magnetic field B 1012 - 1014 Gs. For magnetar B 1015 Gs.

The list of astrophysical objects and phenomena, for which polarizationmeasurements are actual

Binary black holes

Cyg X-1

2-10 keV ~3%>10 keV >10%

370-850 keV >75%

OSO-8 2.4-2.8 keV ~2.4% 4.8-5.6 keV ~5.3%

SEPARATION OF TWO CONTRIBUTIONS TO THE HIGHENERGY EMISSION OF CYGNUS X-1: POLARIZATIONMEASUREMENTS WITH INTEGRAL SPI 1E. Jourdain1, J. P. Roques1, M. Chauvin1 and D. J. Clark1,2

Neutron Stars, Pulsars, Pulsar Wind Nebulae, and Magnetars

Crab Nebula

OSO-8 P = 19.2% ± 1.0%

Measuring x-ray polarization in the presence of systematic effects: Known background Ronald F. Elsner*, Stephen L. O’Dell, and Martin C. Weisskopf

Active Galactic Nuclei

Jets from Active Galactic Nuclei

X-Ray and Gamma-Ray Polarization in Leptonic and HadronicJet Models of BlazarsH. Zhang1 and M. BЁottcher2,1

Gamma-Ray Bursts

Application of Jitter Radiation: Gamma-ray Burst PromptPolarizationJirong Mao1,2,3 and Jiancheng Wang2,3

Davide LazzatiNew Journal of Physics 8 (2006) 131

Prompt Emission



Afterglow



Application of Jitter Radiation: Gamma-ray Burst PromptPolarizationJirong Mao1,2,3 and Jiancheng Wang2,3

Non-linear electrodynamics effects.

Geisenberg-Euler

Born-Infeld

,48

1 222

2221

22qBL BEBEBE

Generally

GE: 1 = 5.110-5, 2 = 9.010-5, BI: 1 = 2 = а2Bq2/4, 1/а = 9.81015 Gs

.2

1 240

22022

2,12,1

qq

BkBk

ck BBk

Dispersion equation for Geometry optics approximation and weak flatEM waves in constant dipole neutron star magnetic field .

Non-linear Electrodynamics effects in strong magnetic fields of pulsars andmagnetars:- EM beam bending;- Birefringence;- Splitting

Bending angle for X-Ray source near neutron star (distance l1) for b < l1 (b – impact factor)

BI non-linear electrodynamics (curves 1, а - B0/Bq = 102, б - B0/Bq = 1)Gravitational bending, (curves 2, а – rg/l1 = 0.1, б - rg/l1 = 10-5)

GE non-linear electrodynamics (curves 1, 2 correspond two polarization modes, а - B0/Bq = 0.25, б - B0/Bq = 10-2)

Birefringence: it is following from the dispersion relation that EM waves linearly-polarized in mutually orthogonal planes will delayed to each other.

Non-linear EM signal delay due to birefringence for NS rotation axis directed normally to the magneticdipole plane ~1 mks if GE electrodynamics is valid ( EM signal polarized normally to the magneticmeridian will be delayed relatively signal polarized in this plane).

Signal to noise ratio () for polarization measutements

)(2 NI

PI

N – full number of background counts, P – polarization degree, - modulation factor

For P = 1, = 1 and neglecting the background, it could be obtained fo 3 significance level that to detect100%- polarization at each bin should be detected no less than 20 counts.

tSJmksT эфф120

Then. If pulsation componnet intensity J, cm-2s-1

(T – pu;sation period, t – exposition time, Sэфф – effective area)

For Crab:J(E = 20-100 keV) = 4.610-2 phot/cm2s,J(E = 0.1-1.0 МeV) = 1.210-2 phot/cm2s,J(E = 0.05-1.0 GeV) = 610-6 phot/cm2s.

20-100 keV:1 Crab – S = 103 cm2, t 100 кs,1 mCrab - S = 104 cm2, t 3 Мs

0.1-1.0 МeV:1 Crab - S = 104 cm2, t 100 кs,1 мCrab - S = 104 cm2, t 10 Мs

0.05-1.0 GeV – no real areas ans exposition times allow detect effect

Polarisation measurement problems:- geometry effects (electron beam, disk shape etc)- physical effects (synchrotron emission in ordered magnetic field)- birefringence

What is needing to measure?- polarisation degree & polarisation angle- in different energy bands- with timing

d/d = r02/2(E’/E0)

2(E0/E’ + E’/E0 – 2sin2 cos2),

Klein-Nishina-Tamm cross-section:

Тоmson cross-section:

d/d = r02(1 – sin2 cos2). d = r0

2sin2dd,.

2cos

123

1

minmax

minmax

i

i

kji

ii

iiизм

N

NNN

NNNN

P

Compton polarimeter

dI/d = I/2(1 - Pcos(2( - 0)),

Q = (Nmax – Nmin)/(Nmax + Nmin) = A/B.

Four Detector Assemblies for Hard X-Ray Polarimetry

RHESSI instrument: а – detector assembly on satellite board, б – gamma-quantumdetectors, в – satellite general view.

Fabio Muleri and Riccardo CampanaINAF/IAPS, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy




X-Ray polarimeter based on pixelized microchannel detector

Track imaging detector.

Tracker: double sided Si strip detectors

Calorimeter: 3D resolving LaBr 3 / Si drift diode

Images Classical Tracked Pairs Compton Compton

Principe of GROM-S gamma-calorimeter

The GRIPS-GRM Simulation Model

Tracker: Double-sided Si-strip detectors

50 kg Silicon, 64 layers with 8x8 wafers (10x10x0.05 cm3), 500 μm pitch, 2.5 keV FWHM energy resolution, 10 keV trigger threshold

Calorimeter: LaBr3

500 kg, 0.5x0.5x2/4/8 cm, 4.4% energy resolution (FWHM) @ 662 keV, 0.5 cm depth resolution in 8 cm crystals, 30 keV trigger threshold

ACS: Plastic scintillator

120 kg BC408, 50 keV average veto threshold

166 cm

8. J an ua r 2008 N uc lea r L ine Scien ce w ith G R I P S 6

General view of GROM-S, red are the anti-coincidence shield elements, blue are theSilicon-strip detectors for angular measurements, green are the active shield andLaBr3:Ce calorimeter viewed by Si-photodiods or Si PMTs. просматриваемыйкремниевыми фотодиодами или кремниевыми фотоумножителями

The view of “Gammascope” instrumentThe view of “Gammascope” instrument

The comparison of “Gammascope” sensitivity with other experiments

Compton polarimeter: a – position-sensitive detector pixels, top view, b – PSD pixels, side view.

02cos1

2

P

I

d

dI

Позиционно-чувствительный детектор широкоапртурного гамма-телескопа. Оси координат: X - красная, Y - зеленая, Z - синяя.Зеленый с желтыми точками отрезок --- трек γ-кванта (300кэВ).

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POLARIZATION MEASUREMENTS FOR GRBs. Content 1. Introduction: processes of gamma-ray generation 2. Astrophysical sources (BBH, NS&magnetars, AGN, GRBs