September 25, meeting Tsunefumi Mizuno (Hiroshima Univ.)

Presentation on theme: "September 25, meeting Tsunefumi Mizuno (Hiroshima Univ.)"— Presentation transcript:

1 September 25, 2015@JPS meeting Tsunefumi Mizuno (Hiroshima Univ.)
「すざく」による広がったTeVガンマ線放射VER J のX線観測 (Suzaku Observation of the extended TeV gamma-ray source VER J ) September 25, meeting Tsunefumi Mizuno (Hiroshima Univ.) H. Takahashi, J. Katsuta (Hiroshima Univ.), K. Hayashi (ISAS/JAXA), R. Yamazaki (AGU)

2 Contents Introduction Past obs. in TeV g-rays and X-rays
Observations by Suzaku Data Analysis and Results Discussion Summary 白鳥座X方向、広がったTeVガンマ線放射のX線フォローアップ観測が主題 紹介、観測、解析、議論(Preliminary)

3 Past Obs. by Milagro & VERITAS
Milagro reported an extended TeV g-ray source MGRO J in Cygnus-X direction (s=0.7deg) It was resolved into multiple sources by VERITAS. The most luminous one, VER J , has the following properties smajor=0.34deg, positional coincidence with MGRO J , consistent spectrum in high energy => Main contributor E>1TeV E=0.6-1TeV まず最初にMilagroが報告 分解能に優れたVERITASによって分解。メインがVER J 諸元(morphology)。同じ大きさ・位置の円(座標系は異なる) Abdo+12, ApJ 753, 159 Aliu+14, ApJ 788, 78 Aliu+14, ApJ 788, 78

4 Past Obs. by Milagro & VERITAS
Milagro reported an extended TeV g-ray source MGRO J in Cygnus-X direction (s=0.7deg) It was resolved into multiple sources by VERITAS. The most luminous one, VER J , has the following properties smajor=0.34deg, positional coincidence with MGRO J , consistent spectrum in high energy => Main contributor Possible X-ray counterpart is PSR J & PWN G MGRO J E>1TeV E=0.6-1TeV まず最初にMilagroが報告 分解能に優れたVERITASによって分解。メインがVER J 諸元(morphology) 諸元(スペクトル) Milagroソースのメインとみなせる。 PSR J およびPWNが対応天体の最有力候補 VER J (G=1.75, F(1-10TeV)=6.7x10-12 erg/s/cm2) Aliu+14, ApJ 788, 78 Aliu+14, ApJ 788, 78

5 Past Obs. in X-Rays Possible X-ray counterpart is PSR J & PWN G PSR J : young and energetic (t=17 kyr, dE/dt=3.4x1036 erg/s) Chandra revealed a ~20”x10” pulsar wind nebula (PWN G ) XMM reported faint emission of 5’-10’ length in east (fainter) and west (brighter) 30” これまでのX線観測 PSR J はそもそも強力な電波パルサー Chandraにより、PWNが発見される(10-20”程度) XMMにより、数分角に広がったPWN放射が報告 10’ Hessels+04, ApJ 612, 389 Zabalza+10, J. of Mod. Phys. D. 19, 811

6 Problems of the PSR/PWN Scenario
Possible X-ray counterpart is PSR J & PWN G PSR J : t=17 kyr, dErot/dt=3.4x1036 erg/s PWN G : revealed by Chandra and found to extend out 5’-10’ in length in east (fainter) and west (brighter) Several issues of the PSR/PWN scenario have been pointed out (e.g., Abdo+09, ApJ 799, 1059; Parades+09, A&A507, 241) Large dispersion measure (370 pc/cm3) and rotation measure (524 rad/m2) indicate large distance to the source (d>10 kpc). g-ray luminosity of PSR too high compared to dErot/dt Source size (~90 pc for 0.5 deg at 10 kpc) too large for high-energy electrons to fill before cooling X-rays from only small portion of TeV emission Detailed study of the PWN properties (spectrum, morphology) and search for unknown extended emission by Suzaku-XIS PWN起源説には問題も指摘されている 距離が遠い ガンマ線高度が高い(spin down luminosityに比べて) Egamma(1-10TeV)=8x10^34 erg/s 領域が広い(電子の冷却時間) X線はTeV放射の一部からのみ 広がった放射に強い「すざく」による観測

7 Suzaku Obs. of VER J Two observations conducted in 2014 November. P2 covers region of the PSR/PWN and TeV centroid P3 covers the west part of VER J , in which no strong X-ray sources are reported Net exposure is ~35 ks each (COR>6 GV) Position RA (deg) DEC Net exp. (ks) P2 305.07 36.85 35.0 P3 304.80 36.80 35.7 P2 P3 「すざく」観測の諸元 時期、場所、積分時間 図を用いて説明

8 XIS Image (soft band) Soft band (0.7-2 keV) intensity map (XIS3, in unit of photos/s/cm2/sr) PWN clearly detected in P2 No obvious extended emission in P3 (detailed analysis to be done) Soft bandイメージ、XIS3 P2からはPWNの放射 P3からは、はっきりした放射はない(定量的な解析はこれから) P2, keV P3, keV

9 XIS Image (hard band) Hard band (2-10 keV) intensity map
PWN clearly detected in P2 No obvious extended emission in P3 Size of PWN similar to that in soft band (detailed analysis to be done) hard bandイメージ、XIS3 P2からはPWNの放射 P3からは、はっきりした放射はない PWNのサイズ・形状はsoft bandと似ている(定量的な解析はこれから) P2, 2-10 keV P3, 2-10 keV

10 PWN Spectrum (1) Source Region: 5’ x 13’ around the PWN
(unusable area of XIS0 not used) BG region: the same size, next to the source region in north Bright sources excluded BG sources (excluded) スペクトル解析 領域サイズ、位置、BGサイズ 点源の扱い PWN P2, keV

11 PWN Spectrum (2) Featureless spectrum, fitted by wabs*power-law
X0, X1, X3 chi2/dof=316.2/304 N(H)=0.82(+0.15,-0.14)x1022 G=2.21(+0.16,-0.15) I(0.5-2 keV)=5.66x10-8 erg/s/cm2/sr I(2-10 keV)=20.3x10-8 erg/s/cm2/sr f(0.5-2 keV)=31.1x10-14 erg/s/cm2 f(2-10 keV)=112x10-14 erg/s/cm2 スペクトル解析 吸収を受けたPLで再現可能(非熱的放射が卓越) 吸収量、べき 輝度および積分フラックス(hard bandの方が強い) Unabsorbed spectrum: E2F(E)=642x10-6 (E/keV)-0.21 keV2/s/cm2/keV

12 Discussion and Future Tasks
N(H) of the PWN ~0.8x1022 cm-2, similar to the absorption of the pulsar (Hessels+04) Sources in Cygnus-X (d~1.4 kpc) shows absorption of ( )x1022 cm-2 (Yoshida+11), whereas Galactic total absorption is estimated to be (2-3)x1022 cm-2 (Mizuno+15). => d~3 kpc indicated. Then the size of the TeV emission (~0.5 deg) corresponds to ~25 pc. F(2-10 keV)~1.1x10-12 erg/s/cm2 is obtained for the west part of the PWN F(1-10 TeV)/F(2-10 keV) ~6. It will be further reduced if we include the whole emission of the PWN Aliu+14 proposed an offset PSR(and PWN) scenario, born at the TeV centroid and traveled to the east Detailed study of PWN properties (energy dependence of morphology) and search for (or constraint on) unknown extended emission are important and underway. Analysis of XMM data is also crucial (point source contribution, overall emission from the PWN) 議論 吸収は8x10^21程度、距離は3kpc程度(Cygnus-Xよりは遠いかも)。サイズが小さくなるので、電子coolingの面では楽になる TeV/X線比は6程度。PWN全体を積分すればさらに2倍くらい小さくなると思われる。極端にX線darkではない。 VERITAS論文で議論されているようなoffset PWNが一つの可能性 X線の広がりの詳細、TeV中心より西側からの放射の制限が重要 XMMデータの解析も重要 これらが今後の課題。解析方法・議論について是非コメント頂きたい

13 Thank you for your Attention
Summary VER J is an extended (smajor=0.34deg) and hard (G=1.75) TeV g-ray source in Cyg-X direction PSR J /PWN G is a possible counterpart, but several issues are pointed out (distance, morphology) We conducted deep X-ray observations by Suzaku-XIS PWN clearly detected (N(H)=8x1021 cm-2, G=2.2, f(2-10 keV)=1.1x10-12 erg/s/cm2) distance is likely to be ~3 kpc, FTeV/FX~a few if we include the whole PWN emission Detailed analysis/discussion underway まとめと今後 ご静聴有難うございました。 Thank you for your Attention

14 Reference Abdo+12, ApJ 753, 159 Aliu+14, ApJ 788, 78
Hessels+04, ApJ 612, 389 Zabalza+10, J. of Mod. Phys. D. 19, 811 Parades+09, A&A 507, 241 Yoshida+11, PASJ 63, S717 Mizuno+15, ApJ 803, 74 Abdo+09, ApJ 700, 1059