Polarimetry with the Soft Gamma Polarimetry with the Soft Gamma- - - - PowerPoint PPT Presentation

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Polarimetry with the Soft Gamma Polarimetry with the Soft Gamma- - - - PowerPoint PPT Presentation

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Polarimetry with the Soft Gamma Polarimetry with the Soft Gamma- - ray Detector onboard ASTRO ray Detector onboard ASTRO-H ray Detector onboard ASTRO ray Detector onboard ASTRO H August 15, 2012 ASTRO-H (2014~) ASTRO H (2014~) COSPAR 2012

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SLIDE 1

Polarimetry Polarimetry with the Soft Gamma with the Soft Gamma-

  • ray Detector onboard ASTRO

ray Detector onboard ASTRO-H

August 15, 2012

ray Detector onboard ASTRO ray Detector onboard ASTRO H

ASTRO H (2014~)

COSPAR 2012

  • T. Mizuno, H. Tajima, Y. Fukazawa, S.

Watanabe, R. Blanford, P. Coppi, T. Enoto, J.

ASTRO-H (2014~) SGD

Watanabe, R. Blanford, P. Coppi, T. Enoto, J. Kataoka, M. Kawaharada, M. Kokubun, P. Laurent, F. Lebrun, O. Limousin, G. Madejski,

  • K. Makishima, K. Mori, T. Nakamori, K.

D

, , , Nakazawa, H. Odaka, M. Ohno, M. Ohta, G. Sato, H. Takahashi, T. Takahashi, S. Takeda, T. Tanaka, M. Tashiro, Y. Terada, H. Uchiyama, Y.

1

Uchiyama, S. Yamada, K. Yamaoka, Y. Yatsu,

  • D. Yonetoku, T. Yuasa and SGD team
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SLIDE 2

Introduction: Introduction: Polarimetry Polarimetry of

  • f Cyg

Cyg X X-1 (1) 1 (1)

  • VLBA/LVA reveal a radio-emitting jet from

Cyg X-1. PA is -21~-24 deg.

Radio

  • Polarization is a powerful probe to study

geometries of astrophysical sources (and break model degeneracy)

  • How about the X-ray/γ-ray polarimetry of the
  • bject?

Radio Jet C t i ti Stirling+01 (PA: -21~-24 deg.) Disk reflection Comptonization Pjet=1036-1037 erg/s (Gallo+05) (Gallo+05) 3%-50% of LX

2

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SLIDE 3

Introduction: Introduction: Polarimetry Polarimetry of

  • f Cyg

Cyg X X-1 (2) 1 (2)

  • How about the X-ray/γ-ray polarimetry of the
  • bject?

Radio

  • Previous X-ray and γ-ray polarimetry suffers

large uncertainty. Interpretation (w.r.t. radio jet) not so straightforward.

  • We need better sensitivity in polarization.

Radio Jet C t i ti

X

Stirling+01 (PA: -21~-24 deg.) Disk reflection Comptonization

γ-ray X-ray

Laurent+11

γ y

3

Long+80 hint of pol.@2.6/5.2 keV (disk?) PA: 162+/-13 deg. pol.@E>=400 keV (jet?) PA: 140+/-15 deg.

slide-4
SLIDE 4

Polarization Sensitivity Polarization Sensitivity

  • Minimum Detectable Polarization (pol. degree

distinguishable from statistical fluctuation) distinguishable from statistical fluctuation) R R MDP

B S

29 . 4 + =

99% Confidence

T R M MDP

S

× =

99% Confidence

M: Modulation Factor R : Source rate RS: Source rate RB: Background rate T: Obs. time

  • Larger M
  • Larger RS (Larger Aeff)

S ll R better sensitivity (smaller MDP)

4

  • Smaller RB

(smaller MDP)

A-H (2014~) SGD achieves large M and small RB

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SLIDE 5

ASTRO ASTRO-

  • H

H (2014~) SGD (2014~) SGD

  • Si-CdTe Compton Camera + BGO shiled
  • Constrain incident angle using Compton kinematics
  • Constrain incident angle using Compton kinematics

– efficient background suppression (θ-cut)

2 2

Background Level

cosθ = 1+ mec2 E1 + E2 − mec2 E2

Suzaku HXD-GSO (Data)

Background Level

Tajima+ 10

Compton Scat.

0.1 Crab

  • Proc. SPIE

Photo-abs.

Astro-H SGD

5

BG<=100 mCrab

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SLIDE 6

ASTRO ASTRO-

  • H SGD as a

H SGD as a Polarimeter Polarimeter

  • Si-CdTe Compton Camera + BGO shiled
  • Constrain incident angle using Compton kinematics
  • Constrain incident angle using Compton kinematics

– efficient background suppression (θ-cut) – polarization measurement (φ-measurement) 2

2

p (φ )

cosθ = 1+ mec2 E1 + E2 − mec2 E2

Tajima+ 10

  • Proc. SPIE

Compton Scat.

  • pol. vector

Photo-abs. φ

6

Lei+97 (Concept of Compton polarimeter)

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SLIDE 7

Performance Verification (1) Performance Verification (1)

  • Beam test at Spring-8 (Synchrotron facility in Japan)
  • Use 90-degree scattered photons to reduce the beam
  • Use 90-degree scattered photons to reduce the beam

intensity (~170 keV, 92.5% polarized)

  • Detectors were rotated to study systematic effects

SGD prototype 1 layer DSSD 250 keV (>99.9%) 1 layer DSSD 4 layers CdTe (Btm) 4-sides CdTe 170 keV (92.5%)

  • pol. vector

Takeda+ 10, NIMA

7

Takeda 10, NIMA

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SLIDE 8

Performance Verification (2) Performance Verification (2)

  • Beam test at Spring-8 (Synchrotron facility in Japan)

SGD prototype

  • Data

■ Simulation

A: polarized beam

Modulation Curve = A/B

SGD prototype

M=0 82 is consistent with the expectation

B: non-polarized beam

(Data=0deg+90deg runs)

M=0.82 is consistent with the expectation (0.855) within systematic uncertainty of 3% => verifying the detector concept and simulation

(Data=0deg+90deg runs)

M100~0.58 and efficiency~10% w/ flight configuration

8

Takeda+ 10, NIMA

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SLIDE 9

Background Simulation (1) Background Simulation (1)

  • Background estimation and reduction is a key for the SGD

polarimetry

  • SAA protons (radioactivation) and albedo neutrons (elastic

scattering) are dominant sources of the BG

  • We develop Monte-Carlo simulator to study BG

p y

  • rbit-average flux

SAA protons p Albedo neutrons

9

Yamada

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SLIDE 10

Background Simulation (2) Background Simulation (2)

  • Background estimation and reduction is a key for

the SGD polarimetry. the SGD polarimetry.

150 MeV protons (typical for SGD)

CdTe: data vs. simulation

(active material w/ large Z)

( yp f ) cooling time: 3-5 d cooling time: 18-40 d CdTe or FC

(Murakami+03) Mizuno+ 10, proc SPIE

10

  • Identify several lines (radioisotopes) in bth data and sim.
  • Verify Simulation through a comparison with the beam test data
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SLIDE 11

Background Simulation (3) Background Simulation (3)

  • Background estimation and reduction is a key for

the SGD polarimetry. the SGD polarimetry.

150 MeV protons (typical for SGD)

Fine Collimator: data vs. simulation

(material inside FOV)

( yp f ) cooling time: 10 h cooling time: 2 d cooling time: 13 d

(Murakami+03)

CdTe or FC

Mizuno, Nakajima+

11

  • Identify several lines (radioisotopes) in both data and sim.
  • Verify Simulation through a comparison with the beam test data
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SLIDE 12

Crab Nebula Crab Nebula Polarimetry Polarimetry (Current Status) (Current Status)

N

OSO-8 (Weisskopf+78) PA @2 6/5 2 keV PA @2.6/5.2 keV PD=20%

E

INTEGRAL (Dean+08, Forot+08)

2’

PA@ >100 keV PD=50% aligned with pulsar rot. axis

  • Great success by INTEGRAL SPI/IBIS, but

2

12

large error (~10 deg in PA) prevents unambiguous interpretation

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SLIDE 13

SGD SGD Polarimetry Polarimetry of the Crab Nebula

  • f the Crab Nebula
  • Precise measurement of pol. angle

– comparison with a pulsar rot. axis within a few degree comparison with a pulsar rot. axis within a few degree accuracy

INTEGRAL IBIS SGD Simulation, 100 ks SGD Simulation, 100 ks obs. 50% polarization @80-300keV assumed INTEGRAL IBIS Modulation Curve@200-800 keV (pol. deg.>88% PA=122+-7deg.) g )

13

Tanaka Forot+08

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SLIDE 14

Cyg Cyg X X-

  • 1

1 Polarimetry Polarimetry (Current Status) (Current Status)

  • How about the X-ray/γ-ray polarimetry of the
  • bject?

Radio

  • Previous X-ray and γ-ray polarimetry suffers

large uncertainty. Interpretation (w.r.t. radio jet) not so straightforward.

Radio Jet C t i ti

X

Stirling+01 (PA: -21~-24 deg.) Disk reflection Comptonization

γ-ray X-ray

Laurent+11

γ y

14

Long+80 hint of pol.@2.6/5.2 keV (disk?) PA: 162+/-13 deg. pol.@E>=400 keV (jet?) PA: 140+/-15 deg.

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SLIDE 15

SGD SGD Polarimetry Polarimetry of

  • f Cyg

Cyg X X-1

  • Assume jet component is contaminated by disk Comptonization

in the SGD band (PD<=20%) – still able to disclose weak polarization hidden in Comptonization down to 100 keV

INTEGRAL IBIS SGD Simulation, 300 ks 10% polarization @100-180keV INTEGRAL IBIS Modulation Curve@250-400 keV (PD<=20%) p 17% polarization @180-330keV ΔPA~2 deg 17% polarization @180 330keV

15

Tanaka Laurent+11

ΔPA~3 deg

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SLIDE 16

Summary Summary

  • Polarization measurement can place constraints on

source geometry (qualitatively new information) source geometry (qualitatively new information)

  • Astro-H SGD is a Compton polarimeter. It is well

validated through experimental test and simulation.

  • The SGD is able to precisely measure polarization from

Crab Nebula and Cyg X-1. Can constrain magnetic field (and disk) direction within a few degree. (and disk) direction within a few degree.

Thank you for your Attention

16

Thank you for your Attention

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SLIDE 17

Backup Slides Backup Slides Backup Slides Backup Slides

17

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SLIDE 18

A Jet A Jet-

  • blowing Ring

blowing Ring

  • Large scale ring-like structure inflated by the inner jet

G ll 05 Gallo+05

~5 pc ring @ 1.4 GHz Pjet=1036-1037 erg/s milliarcsec-scale radio jet

18

radio jet

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SLIDE 19

X-

  • ray/Gamma

ray/Gamma-

  • ray

ray Polarimetry Polarimetry

  • Why polarization? (1) place constraints on source

geometries (2) break model degeneracy geometries (2) break model degeneracy

– Synchrotron emission (magnetic field) – Compton up-scattering radiation (see photons, disk) P l d t QED l l ti it ( t i t – Pol. due to QED or general relativity (constraints on fundamental physics and compact object)

PWN Pulsar BHB, AGN

19

Magnetic field, Accelerated electrons Pulsar emission model, QED Accretion disk, Jet X/γ-ray pol. not subject to Faraday rotation/depolarization

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SLIDE 20

X-

  • ray/Gamma

ray/Gamma-

  • ray

ray SpectroPolarimetry SpectroPolarimetry

  • Measuring energy dependent polarization is crucial to

disentangle emission mechanisms disentangle emission mechanisms

– transition from one pol. generation process to another may

  • ccur over broad energy range

disk reflection model (Matt+93) Blazar model (Poutanen94) 10% disk reflection model (Matt+93)

  • pol. vector disk

Blazar model (Poutanen94)

  • n flux

1% degree h t e photo 1%

  • pol. d

synchrotron IC total

  • l. degree

20

3 10 keV 50 0.1% IC po ** pol. may be low in EC **