PoGOandGlast_2005-11-25.ppt Hard X-ray Polarimeter PoGO and GLAST mission ( 硬 X 線偏光観測 PoGO 計画と GLAST との連携 ) November 25, 2005, GLAST Science Workshop at Titech Tsunefumi Mizuno (Hiroshima University) for the PoGO Collaboration mizuno@hirax6.hepl.hiroshima-u.ac.jp Outline: • Introduction • PoGO mission • Hardware Developments • Scientific Targets 1
PoGOandGlast_2005-11-25.ppt Progress of X- -ray Astrophysics ray Astrophysics Progress of X Energy Resolution at 5.9 keV Point Spread Funciton Einstein Uhuru Tenma (IPC) (SPC) ASCA (SIS) Einstein ROSAT Chandra (IPC) Chandra (PSPC) (ACIS) Suzaku (HEG) (XRS) Sensitivity • In X-ray Astrophysics, the Uhuru imaging capability, spectral resolving power and point Einstein source sensitivity have (IPC) Chandra improved by orders of (ACIS) magnitude. However, … 2
PoGOandGlast_2005-11-25.ppt (Little) Progress of Polarization Measurement (Little) Progress of Polarization Measurement Crab Nebula Polarization measurement with OSO-8 (1976) Modulation curve for 2.6 keV Crab Nebula signal+BG BG Intensity of the source from which pol. was detected • Two carbon Bragg diffraction polarimeters @2.6 keV and 5.2 keV • 19.2+-1.0 % polarization from Crab Nebula (Weisskopf et al. 1976) • Signal/BG ratio was ~9(2.6 keV)/2(5.2 keV) Results has not been surpassed • No significant (3 σ ) pol. detection from Crab for ~30 years, but PoGO (Polarized pulsar Gamma-ray Observer) can do! 3
PoGOandGlast_2005-11-25.ppt What can polarization tell us about HE objects? What can polarization tell us about HE objects? --- Processes known to polarize hard X-rays --- • Synchrotron emission: pol. vector is perpendicular to magnetic field and can tell us the direction of the field. • SNRs, Pulsars, AGN jets, micro-quasars and GRBs • Compton Scattering: pol. vector is perpendicular to the plane of scattering and can tell us the geometry of the photon source and the scatterer (e.g., accretion disk) • BH binaries, Seyfert AGNs • Propagation of photons in strong magnetic field: photons with pol. vector perpendicular to magnetic field are highly absorbed. Good for the test of quantum electrodynamics and reconstruction of the direction of the magnetic field. • Isolated pulsars, NS binaries with a strong cyclotron line. • Polarization is a powerful tool for the direct measurement of source geometry. 4
PoGOandGlast_2005-11-25.ppt Concept of the Compton Polarimeter Polarimeter Concept of the Compton Utilize azimuthal angle asymmetry of Compton Scattering to measure hard X-ray polarization Klein-Nishina cross section pol. vector σ 2 2 d r k k k = + − θ φ 2 2 0 0 2 sin cos Ω 2 d 2 k k k 0 0 φ Azimuthal angle distribution 90degree scattering is the best for the polarization measurement 0 degree 45 degree Modulation Factor is defined as 135 degree − N N ⊥ ll + N N 90 degree ⊥ ll 5
PoGOandGlast_2005-11-25.ppt Polarized larized G Gamma amma- -ray ray O Observer ( bserver (PoGO PoGO) ) Po • Utilize well-type phoswich counter design: plastic scintillators (main detector) shielded by slow scintillators (active collimator) and side/bottom BGO. Similar to Suzaku HXD-II. • Energy band is 30-100 keV: Non-thermal process is dominant and photons are expected to be polarized in many objects. • Low background (~10 mCrab) and large effective area (240 cm 2 ): very high sensitivity for polarization. plastic passive/active scintillator collimator side BGO bottom BGO PMT 6
PoGOandGlast_2005-11-25.ppt Uniqueness of PoGO PoGO Uniqueness of Extremely high sensitivity • Ultra-low BG: only 10-20 mCrab minimum detectable pol. degree is • Large Effective Area: 230 cm 2 @40 keV ~3 % for 100 mCrab (1 σ ) by a single, 6 • Narrow FOV: 1.25 msr hours balloon flight Modulation Curve for 100 mCrab source Expected source and BG spectra 1 Crab 100 mCrab Signal/BG=5 MF=23.79+-0.72 % BG BG total (CXB/ atmospheric downward/upward) Balloon-borne mission: • very low cost • possible observation of flaring events (alerted by, e.g., GLAST) 7
PoGOandGlast_2005-11-25.ppt Collaboration/Schedule of the Mission Collaboration/Schedule of the Mission • United States: NASA/GSFC, SLAC and Princeton Univ. Balloon Flight, DAQ, Beam Test and plastic scintillators • Japan: Tokyo Institute of Technology, Hiroshima Univ., Yamagata Univ. and JAXA/ISAS • PMTs, Beam Test and MC Simulation • Sweden and France: Royal Institute of Technology, Stockholm Univ. and Ecole Polytechnique PMTs, BGO scintillators and Reflectors 2003 2004 2005 2006 2007 2008 Proposal Proton Beam to NASA Test (Osaka) PoGO Balloon Flight Spring8/Argonne KEK KEK/Argonne Beam Test Beam Test Beam Test 1 st prototype 2 nd prototype (fast scinti. 7 units) Flight Instrument (fast/slow 19 units+anti) Integration and Test GLAST Launch & Obs. 8
PoGOandGlast_2005-11-25.ppt Argonne Beam Test (2003) Argonne Beam Test (2003) • 60,73 and 83 keV synchrotron beam Modulation Curve for 73 keV beam • Tested prototype detector (7 units fast scintillators) as well as Geant4 simulaiton Modulation Factor: 42+-1 %(data) vs. ~47 %(simulation) beam direction • Validated prototype on 10 % level. • Bugs in Geant4 (pol. processes in Rayleigh scattering and Compton Scattering) were found and reported. (more than a year ago….) • Details are in Mizuno et al. (NIMA, 2005). 9
PoGOandGlast_2005-11-25.ppt KEK Beam Test (2004) KEK Beam Test (2004) • 30,50 and 70 keV synchrotron beam • Tested prototype detector with flight-design PMTs Beam Injection • Flight configuration scintillators and PMTs were tested. • Lowest energy X-rays for PoGO were tested and validated. • Details are in Kataoka et al. (SPIE, 2005). 10
PoGOandGlast_2005-11-25.ppt Laboratory Test of prototype (2005) Laboratory Test of prototype (2005) • 2 nd prototype with a long hexagonal slow tube and BGO is now being tested. • Used a strong Am source and Compton Scattering technique to generate polarized X-rays in laboratory: very low cost and high flexibility. • M. Ueno (Titech), K. Yamamoto (Hiroshima Univ), T.P. Ylinen and B.G. Kiss (KTH) 3 days data for 0 degree run Pulse Shape Discrimination slow shaper out technique to select fast scint. events. MF = 22+-6 % (taking BG into account) consistent with G4 sim. fast shaper out This new prototype will be tested at KEK next month. 11
PoGOandGlast_2005-11-25.ppt Possible Targets for PoGO(1) Possible Targets for PoGO(1) Crab Pulsar obs. by PoGO can distinguish among pulsar emission models Modulation Curve for the 1 st peak Dyks and Rudak, ApJ, 2003 polar cap model caustic model outer gap model Polar cap Caustic Outer gap GeV gamma-ray spectrum from Vela pulsar Outer gap model E 2 *Flux Polar cap model GLAST + PoGO will provide a very strong restriction on the pulsar emission mechanism. 0.1 1 10 100 GeV 12
PoGOandGlast_2005-11-25.ppt Possible Target for PoGO PoGO (2) (2) Possible Target for Geometry of Astrophysical Jets Multi-band spectrum of Mrk 501 • High Frequency-Peaked BL Lac Objects (HBL) • observe in flaring state notified by, e.g., GLAST. • Multi-wavelength spectrum by GLAST and PoGO can also constrain the jet mechanism. • Galactic microquasars 20 MeV-300 GeV • GRS 1915+105/GRO J1655-40 (GLAST) 30-100 keV (PoGO) Other Possible Targets • Galactic BHBs in hard state: accretion disk geometry • Cyg X-1, GX339-4, etc. • Binary pulsars with cyclotron line: propagation of photons in magnetic field • Her X-1, Cen X-3, Vela X-1, etc. ~10 Galactic/extragalactic high energy object could be observed by PoGO 13
PoGOandGlast_2005-11-25.ppt Summary Summary • PoGO is a balloon-borne instrument scheduled to be launched in 2008 and will open an new window in high energy astrophysics, i.e., polarization. • It is based on a well-type phoswich counter design and has a very high sensitivity down to 10 % polarization from 100 mCrab source. ~10 Galactic/extragalactic objects could be observed. • Test of the 2 nd prototype started. • Collaboration of GLAST and PoGO will provide a strong constrain on the emission mechanism of pulsars, AGN/micro-quasar jets, etc. 14
PoGOandGlast_2005-11-25.ppt Backup Slides Backup Slides Backup Slides for discussion 15
PoGOandGlast_2005-11-25.ppt Galactic Black Hole Binaries Galactic Black Hole Binaries 16
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