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Suzaku Observation of the Fermi Cygnus Cocoon Tsunefumi Mizuno, Toshiaki Tanabe, Hiromitsu Takahashi (Hiroshima Univ.), Katsuhiro Hayashi (ISAS/JAXA),

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Presentation on theme: "Suzaku Observation of the Fermi Cygnus Cocoon Tsunefumi Mizuno, Toshiaki Tanabe, Hiromitsu Takahashi (Hiroshima Univ.), Katsuhiro Hayashi (ISAS/JAXA),"— Presentation transcript:

1 Suzaku Observation of the Fermi Cygnus Cocoon Tsunefumi Mizuno, Toshiaki Tanabe, Hiromitsu Takahashi (Hiroshima Univ.), Katsuhiro Hayashi (ISAS/JAXA), Ryo Yamazaki (Aoyama Gakuin Univ.), Isabelle Grenier (CEA Saclay) and Luigi Tibaldo (SLAC National Laboratory) 1. Introduction: Fermi Cygnus Cocoon Extended hard GeV  -ray excess [1] in Cygnus-X. Its spectrum and morphology imply an interstellar origin => CR production in star-forming region Fermi-LAT data alone cannot determine the particle type => X- ray observation by Suzaku [2] 2. Observation: Suzaku View of the Cocoon 3. Analysis: Spectra of Extended Emission 4. Discussion: Constraint on X-rays and the Cocoon MW Spectrum 5. Summary: Two source observations (positions with strong GeV  -ray excess) Two background observations to estimate the contribution from CXB (Cosmic X-ray Background) and GRXE (Galactic Ridge X-ray Emission; [3]) Employ a model to represent local emission+GRXE+CXB and search for possible non-thermal excess from the cocoon. (We used thin-thermal model vapec/apec [4] to represent local emission/GRXE) kT=0.1 keV (Local Bubble or SWCX; [5]) kT<=1 keV (soft component of GRXE) kT>=1 keV (hard component of GRXE) CXB (parameters taken from [6]) Low-energy lines at ~0.55 keV (forbidden O VII )=>significant contribution from SWCX(Solar Wind Charge eXchange) Spectra of all four regions are successfully reproduced by our model (no significant excess) High-temp plasma model might obscure the emission from the cocoon => examine latitude dependence Uncertainty of CXB and NXB taken into account Monotonic decrease with increasing latitude => most of the extended emission from GRXE Robust upper limit in source positions obtained by subtracting intensity of BG2 MW spectrum from radio[7], X-ray(this study), GeV  -ray[1] and TeV  -ray[8] Model curves of electron scenario with an amplification factor of GeV and cutoff at 1, 5, 10, 50 and 100 TeV. l=25 pc (1 o at 1.4 kpc) and B=20  G (pressure balance with gas) assumed. X-ray data requires a cutoff (in electron scenario) at <=30 TeV, independent confirmation of cutoff at <=5 TeV inferred by TeV data Positions of obs. on a  -ray excess count map (E>=10 GeV) S1 S2 BG2 BG1 soft band (0.7-2 keV) hard band (2-10 keV) Source1 Source2 Background1 Background2 We identified several point sources and small-scale structures and removed them. Unusable area excluded & non-X-ray background subtracted. => Study extended emission (sec.3) (~1/2 of point sources show absorbed hard spectrum and likely to be background AGNs) vapec1 + wabs2*apec2 + wabs3*apec3 + wabs*Power-law XIS1 of Source1 Source1 (XIS0, XIS1, XIS3) Source2 Background1Background2 (radio) (X-ray) (GeV) (TeV) We conducted a series of deep X-ray observations of Fermi Cygnus Cocoon using Suzaku-XIS Most of extended X-ray emission above 2 keV comes from GRXE. X-ray upper limit requires a cutoff (in electron scenario) at <=30 TeV, consistent with a cutoff inferred from TeV data. Paper in preparation. Reference : [1] Ackermann+11, Science 334, 1103 [2] Mitsuda+07, PASJ 59, S1 [3] Worall+82, ApJ 255, 111; Warwick+85, Nature 317, 218; Koyama+86, PASJ 38, 121 [4] Smith+01, ApJL 556, 91 [5] Fujimoto+07, PASJ 59, 133 [6] Kushino+02, PASJ 54, 327 [7] Taylor+03, ApJ 125, 3145 [8] Abdo+12, ApJ 753, 159;


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