Observation of Gamma-Rays from Relativistic Electron Precipitation with Balloon Experiment around the Polar regions

Transcription

1 Observation of Gamma-Rays from Relativistic Electron Precipitation with Balloon Experiment around the Polar regions Yoshitaka Mizumura (Kyoto Univ.) T. Tanimori, H. Kubo, A. Takada, J. D. Parker, T. Mizumoto, S. Sonoda, D. Tomono, T. Sawano, K. Nakamura, Y. Matsuoka, S. Komura, S. Nakamura, M. Oda, S. Iwaki (Kyoto Univ.), K. Miuchi (Kobe Univ.), E. Trunen (Sodankylä Geophys. Obs.), and M. Yamauchi (Swedish Institute of Space Physics)

2 Science targets of SMILE Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment Nucleosynthesis Supernova remnants (SNR), Galactic plane mapping of 26 Al, 60 Fe Strong gravitational potential Black hole candidates Cosmic ray acceleration Active galactic nuclei, SNR, etc. Evolution of universe Gamma-ray bursts from early universe Geophysics Terrestrial Gamma-ray bursts (Relativistic Electron Precipitation) MeV gamma-ray Astrophysics Crab GRB AGN Circumpolar flights with balloon 2

3 Gamma rays from REP 3 Proton kev electron 15 min. Simulation by E. Turunen et al (2009) K. R. Lorentzen et al., (2000) sec scale MeV REP Auroral electrons

4 Status of MeV Astronomy MeV gamma-ray sky CGRO/COMPTEL (1-30 MeV map) GeV gamma-ray sky Fermi/LAT (> 1 GeV map) Two big problems in MeV 1. Imaging is not easy 2. Huge background ~30 sources V. Schönfelder+ (A&AS, 2000) P. L. Nolan+ (ApJS, 2012) MeV gamma-ray window is one of unopened frontier!! SMILE has potential of clearing the problems ~2000 sources 4

5 5 Difficulties of MeV gammas gamma GRB J. M. Ryan (NewAR, 2004) φ event circle E 1 (Recoil Electron) E 2 (Scattered Gamma) G. Weidenspointner+ (A&A, 2001) V.Schönfelder (2004) Suggestion Low background is most artifact important for next MeV detector R. van Dijk (Ph.D thesis, 1996) 1. Good angular res. = good Energy res. 2. Redundancies (TOF, Kinematics, de/dx) 3. Measurement of electron direction 4. Low-z material and light weight 5. Short timing gate

6 Electron Tracking Compton Camera gas muon track electron track Advanced Imaging Photon by photon direction BG rejection Kinematics (alpha angle) Particle ID by de/dx Large FoV ~3 sr Light weight (Reduce of BG source) no use Electron track use Electron track p + n 0.74 MBq 0.85 MBq stopped e - Particle ID by de/dx 3.2 MBq Three 137 Cs sources ~ 4 times better contrast!! 6

7 SMILE-I SMILE-II Event Selection Diffuse Cosmic g 1 m SMILE-II SMILE-I (10cm) 3 size detector Operation test at balloon altitude Diffuse cosmic + atmospheric gamma-ray spectra 8 hours success Japan (Sep. 1, 2006) (30cm) 3 size detector Gamma-ray Imaging test Observation of Crab and/or Cyg X-1 Requirements for detection effective area >0.5 cm 2 angular resolution <10 o Takada et al. ApJ (2011) 1 m one day Fort Sumner ( ) 7

8 Performance test in Lab. 137 Cs (662 kev) gamma-ray source at 15 deg. 30 deg. 60 deg. Wide Field of View (> 3 sr) Angular Resolution Measure 5.3 o 662 kev Imaging test of Low intensity source 22 Na (511 kev) 31 kbq (Requirement < 10 o ) same order of S/N with expectation of Crab obs. 10.8σ (5.4 h) 8

9 Efficiency & Effective Area SMILE-II (30cm FM) without side PSAs SMILE-II (10cm proto.) SMILE-I (10cm) Current Effective Area ~1 cm 2 (Requirement > 0.5 cm 2 ) Compton electrons in TPC ~100% detection!! Simulated Effective Area Further Improvements CF 4 gas + 3 atm. ~10 cm 2 + double scintillator ~20 cm 2 Similar effective area to COMPTEL But 3 sr FoV, Low background, Clear Imaging in SMILE 9

10 Test in high BG environment 10 Continuum MeV gamma rays & Neutrons from water target 140 MeV Protons ~5 times higher than Balloon flight (~2 times of circumpolar flight) checking source is clearly appeared!! ~1 order suppression of BG using de/dx & fiducial cut 662 kev

11 Sensitivity & SMILE-III 10 6 sec, 3σ detection Preliminary Expected Detection Significance of Crab SMILE-II Kiruna SMILE-III (10cm 2 ) Japan SMILE-satellite SMILE-II (in USA) Collaboration with Goddard ( now planning) 30cm ETCC with 1~4 cm 2 Imaging of Crab and/or Cyg X-1 above 5σ level SMILE-III (in Polar region) Upgrade to cm 2 ETCC Survey of Galactic Plane Anisotropy of diffuse MeV radiation Gamma rays from REP bursts 11

12 Feature of SMILE for REP bursts Wide FoV (>3 sr, about 300 km radius) and Energy range (0.1 several MeV) is suitable for REP bursts monitoring 100 REP events / 1 day Measurement of position and spectrum of REP Measuring vertical and lateral spreads of far distant REP & Micro bursts Detecting Proton precipitation (> 10 MeV) by secondary neutrons Micro bursts 12

13 Summary SMILE has both of efficient BG rejection ability and high contrast imaging using electron direction SMILE-II (1 4 cm 2 effective 0.3 MeV) will be planned one day balloon flight(s) in USA in 2014, 15 for the observation of Crab/Cyg X-1 SMILE-II will be upgraded to SMILE-III (> 10 cm 2 effective area) in 2016 In the long duration balloon flight (~1 month) around the polar region, SMILE-III will measure ~10 celestial objects, extragalactic diffuse gamma-ray radiation, Galactic Plane survey, and > 1000 REP events. 13

14 Measuring of Polarization No polarization (Detector Response) 0 deg., 100% 45 deg., 100% Response Correction Modulation factor 200 kev Polarization of the Crab can be measured by SMILE-III ETCC 14

15 15 Poster OS-P23