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超新星遗迹的射电巡天观测和甚高能伽玛射线源研究

超新星遗迹的射电巡天观测和甚高能伽玛射线源研究. 田文武 2008 年 6 月 5 日在北京大学的报告. 射电天文的重大发现. 1951 年，星际 HI 谱线 1965 年， 3K 微波背景 1967 年， 脉冲星 , VLBI 1968 年，星际分子 1971 年，视超光速运动 1974 年， 脉冲双星 / 引力波 …. 概要. 21 厘米中性氢原子 (HI) 谱线银道面巡天简介及建立新方法 (Tian & Leahy 方法 ) 获得可信赖的超新星遗迹和相关联天体的距离 ( 或范围 )

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超新星遗迹的射电巡天观测和甚高能伽玛射线源研究

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  1. 超新星遗迹的射电巡天观测和甚高能伽玛射线源研究超新星遗迹的射电巡天观测和甚高能伽玛射线源研究 田文武 2008年6月5日在北京大学的报告

  2. 射电天文的重大发现 1951年，星际HI谱线 1965年，3K微波背景 1967年，脉冲星, VLBI 1968年，星际分子 1971年，视超光速运动 1974年，脉冲双星/引力波 ….

  3. 概要 • 21厘米中性氢原子(HI)谱线银道面巡天简介及建立新方法(Tian & Leahy方法)获得可信赖的超新星遗迹和相关联天体的距离(或范围) • 超新星遗迹和分子云的相互作用导致很多天体物理现象,如加速带电粒子到相对论能量, 产生可以观测到的TeV伽玛射线. 测定天体的距离可以直接检验超新星遗迹是河内宇宙线粒子起源处的合理性 • 实例: 四个超新星遗迹和TeV源相关联系统:G29.7-0.3/PSR J1846-0258/HESS J1846-029, G21.5-0.9 /PSR J1833-1034/HESS J1833-105, G23.3-0.3/HESS 1834-087,G353.6-0.7/HESS J1731-347; 一个含异常X-光线脉冲的年青超新星遗迹 G27.4+0.0 /AXP 1E1841+045;一个正与临近大CO分子云相互作用的超新星遗迹 G18.8+0.3; 及一个产生1720兆赫兹OH脉泽辐射的年青超新星遗迹 G21.8-0.6.

  4. 21-cm HI observations in the Milky Way disk

  5. 1420MHz and 13CO data ( + X-ray data) 1420 MHz data from the VLA Galactic Plane Survey (Still et al. 2006, AJ, 132, 1158): Range:18<l<67d, -1.3<b<2.3d FWHM: 1'×1'×1.56 km/s Velocity range:-113– 165 km/s rms :2 K per channel Short-spacing information for the H I line emission from observations with the 100m Green Bank Telescope • 13CO(J=1-0) data from the Galactic ring survey (Jackson et al.2006, ApJS, 163, 145) by the Five College Radio Astronomy Observatory 14m telescope: • Range:18<l<56d, -1<b<1d • FWHM:46"x46"x0.21 km/s • rms:~ 0.13 K per channel. • Velocity range: -5-- 135 km/s • (<=40d), -5-- 85km/s(>=-40d)

  6. An example to build absorption spectra to Kes 75 (a TeV source) T 21 cm HI map from VLA+GBT observations with contours (28 40 60 100 k) overlaid 1420 MHz map from VLA D-array observations. Ton (v)-Toff(v)=(Ts-Tbg)(1-e^{-tau}) solid-line box ---> Ton(v) Annulus background Toff(v)

  7. HI+CO13 spectra show that the highest absorption velocity~95 km/s, absence of absorption at ~102 km/s, the tangent point velocity ~110 km/s. So d ~ 5.1 to 7.5 kpc

  8. Rotation curve of Milky Way stays flat with distance

  9. Calculated radial velocity as a function of distance along a line of sight in the Galactic plane at l = 29.7 degree Formula: Vr= Ro sin l (V(R)/R – Vo/Ro). V(R):circular orbit speed of a star; R:Galactocentric radius; Vr:radial velocity

  10. The long-standing puzzle on Kes 75/PSR J1846-0258 is resolved (Leahy & Tian, 2008, A&A, 480, L25. 已7次独立引用, 改写了前面的结果:Becker & Helfand, 1984, ApJ, 283, 154,被引用36次) 1. Significant distance revision from ~19 kpc to ~ 6 kpc for Kes 75 gives a normal explosion energy (~2x10E51 erg) from a core collapse, contrary to the highly implausible value (~10E53 erg) for an extremely high X-ray luminosity for Kes 75 (~4x10E37 ergs /s) obtained previously due to d ~ 19 kpc. 2. Small radius ~ 3 pc (1.6') for Kes 75 argues that it harbors a Crab-like rotation powered young pulsar J1846-0258 and PWN (723--884 yr) , rather than the previous inferred, much higher ratio of the pulsar-plus-nebula luminosity to spin-down luminosity.

  11. Kes 73 new results: 1.Absorption features appear up to tangent point velocity (~110 km/s) 2.At 114 km/s, the HI distribution is quite inhomogeneous. 3.The HI feature at 84 km/s is at the far distance Conclusion: Kes 73 is in front of the HI at 84 km/s, but beyond the tangent point.

  12. ~110 km/s tangent point ~84 km/s • HI+CO spectra confirm the above conclusion. • The CO cloud (~89 km/s) is behind Kes 73. Limits to distance of Kes 73/AXP 1E1841-045 between the far distance (9.4 kpc) of 89 km/s and the tangent point (7.5 kpc) which was used as an upper limit in past 20 yrs. • Kes 73 has a refined age of 500 to 1000yr, the AXP has a larger 50% X-ray luminosity. • Tian & Leahy, ApJ, 2008, 677, 692 ~89 km/s

  13. SNR/Cloud interaction • 1. Detection of high energy gamma ray and non-thermal X-ray emission • 2. Detection of 1720 MHz shock-excited OH masers ---"signposts" of SNR-molecular cloud interactions. • 3. Detection of high line rates CO(2-1)/CO(1-0) and broad wings of 10–20 km/s in CO and other molecular spectra (Moriguch et al. 2005, ApJ, 631, 947). • 4. Detection of shocked H2 emission from the system at near-infrared band (Reach et al. 2005, ApJ, 618, 297). • Direct method: Determine distance to a SNR/CO Cloud system by HI+CO obs. Emit TeV gamma-rays Schematic of an expanding SNR interacting with an adjacent molecular cloud (Wardle & Yusef-Zadeh 2002)

  14. The distance to Kes 69 and G21.5-0.9 Green A.J. et al. (1997, AJ, 114, 2058) suggested a far distance (11.2 kpc) of the 1720 MHz OH maser velocity 69.3 km/s by HI+OH obs. New VLA 1420 MHz map 1 Old OH maser at 69.3km/s New OH Maser at ~84km/s pwn G21.5-0.9 X-ray (contour --ROSAT PSPC)+radio (grey from NVSS) image from Yusef-Zadeh et al. (2003, ApJ, 585, 319)

  15. Kes 69 • HI spectrum: max velocity of absorption ~86 km/s; HI emission feature at 113 km/s with no respective absorption. • CO image + spectrum: adjoining cloud at ~ 85 km/s, no prominent cloud around 70 km/s towards the bright southern shell. • New detected 1720 MHz OH maser at velocity 80-86km/s from within the southern shell of Kes 69. • Conclusions: distance of ~5.5 kpc to Kes 69, and physical interaction between Kes 69 and adjoining cloud.

  16. y (from Jack Hewitt) Spitzer image GBT map VLA D-Array Integrated1720 MHz line intensity OH maser Vo=84 km/s

  17. G21.5-0.9 and PMN J1832-1035 1. The highest absorption velocity~66 km/s, no absorption at~71 and 86 km/s 2. G21.5-0.9 is likely at 4.4 – 4.8 kpc (near side of ~ 71 km/s) or possibly at 4.4 – 8 kpc (far side of ~86 km/s)

  18. http://www.mppmu.mpg.de/~rwagner.sources

  19. vFv spectrum of a young SNR with an age 10^3 yrs The thick-solid line shows the total non- thermal flux. Hadronic emissions are Pion-decay gamma- rays (thin-solid), synchrotron (dot-dashed) and bremsstrahlung emission (short-and- long dashed) from secondary electrons produced by charged pion. Leptonic emissions are synchrotron (long- dashed), inverse-Compton (dotted) and bremsstrahlung (short-dashed) emission by primary electrons. an old SNR case an illuminated GMC an old SNR-a GMC

  20. The HESS J1731-347 image ( Aharonian et al. 2008, A&A, 477, 353); Contours start at 4 sigma in 1 sigma steps, which is of gamma-ray excess counts smoothed with a Gaussian filter with standard deviation 0.1 degree. Energy range:0.50 to 80 TeV. A power-law fit to the spectral data (E=N0E^{-Г}),Г=2.26±0.10

  21. Two SNR and TeV HESS source Systems 1. Discovery of the Radio and X-ray counterpart of TeV gamma-ray Source HESS J1731-347 W.W. Tian(1,2), D.A. Leahy(2), M. Haverkorn(3), B. Jiang(4) (2008 June 1, ApJL, 679, 85) • 1. National Astronomical Observatories of China, CAS, China • 2. Department of Physics & Astronomy, Uni. of Calgary, Canada • 3. Astronomy Department, Uni. of California-Berkeley, USA • 4. Department of Astronomy, Uni. of Massachusetts, USA 2.First evidence: an old SNR encounters a GMC to emit TeV gamma-rays in the cloud: W41/HESS J1834-087 W.W. Tian(1,2), Z, Li(4), D. Leahy(2), Q.D. Wang(4) (2007, ApJL, 657, 25. 已13次引用, 其中9次独立引用):

  22. SNR G363.6-0.7? Left: the continuum image of G353.6-0.7 at 1420 MHz from the Southern Galactic Plane Survey (SGPS, ATCA data) with a beamsize of 100 arcsec and a sensitivity of < 1 mJy/beam (Haverkorn et al. 2006, ApJS, 167, 230) Right: the 843 MHz image from the Molonglo GPS with a beamsize of 43 arcsec and a sensitivity of 1~ 2 mJy/beam (Green et al. 1999, ApJS, 122, 207)

  23. X-ray and IR Images: a likely SNR Left: ROSAT PSPC image (0.1-2.4 kev), centred at l=353.55, b=-0.6 integration time of 300 s, Signal-to-Noise ratio ~ 5 Right: 8 micro mid-infrared image, centred at l=353.5, b=-0.65 from the GLIMPSE Legacy survey with resolution of ~2 arcsec (Benjamin et al. 2003, PASP, 115, 953). No thermal emission down to a limit of 0.4 mJy (5 sigma), G353.6-0.7 is not an HII region!

  24. Spectral Index of G353.6-0.7 Total flux density estimayes of 2.2±0.9 Jy at 1420 MHz and 1.4±0.3 Jy at 5 GHz (Parkes observations, Haynes et al. 1978, Austr. J. of Phys. Suppl. 45, 1) by same method, give = 0.4(- 0.6/+0.5), favour a non-thermal feature. The 843 MHz data misses too many low spatial frequency components to be used to obtain a reliable flux density. ACTA+Parkes image. The ring shows the boundary of SNR G353.6-0.7. Azimuthally averaged flux over the low half of G353.6-0.7 as a function of radius from the center of the remnant.

  25. Distance to G353.6-0.7 Too faint to obtain HI absorption spectrum of the new SNR. HII region G353.42-0.37 is adjacent to the SNR. The HI absorption spectrum features in the range of 9 to -24 km/s show G353.42-0.37 is at the distance (~ 3.2 kpc) of its recombination line velocity (~ -16 km/s). A number of HESS sources are detected where high-energy particle accelerators are located near H II regions, and other such accelerators without proximate sources of low-energy photons are weak or undetected at TeV energies, Helfand et al. (2007) suggested that TeV emissions of HESS sources could originate from inverse Compton scattering of the starlight from the nearby H II regions. SNR G353.6-0.7 may be at ~3.2 kpc.

  26. Overlapping Radio (grey)+X-ray (red)+gamma-ray (green) images of G353.6-0.7 1. The radio and X-ray morphologies of G353.6-0.7 near-perfectly march the outline of HESS J1731-347. 2. The low half seen in X-rays and upper half not seen in X-rays is likely due to clouds' absorption, which is revealed by the 12CO column density increasing towards the Galactic plane.

  27. How old is G353.6-0.7? 1. An old SNR: a large angular size of 0.5 degree and a physical size of ~28 pc in diameter (assuming a distance of ~ 3.2 kpc); faint radio and X-rays. 2. Ambient density n0 ~5 cm-3, estimated by known flux (~1.2E-11 cm-2 s-1, assuming a conversion efficiency ~ 0.1 and explosion energy 10E51 ergs, Aharronian et al. 2006 ApJ, 636, 777), 3. An age of ~27,000 yr, based on a Sedov model (Cox 1972, ApJ,178, 159), it is entering a radiation phase. 4. It is not too old < 100000 yrs, because the X-rays are visible in G353.6-0.7 and an old SNR is expected to emit few thermal X-rays from the high T gas heated by the fast-enough shock

  28. W41/HESS J1834-087 • XMM-Newton observations show diffuse X-ray emission within the HESS source J1834-087--- this suggests an association between the X-ray and TeV gamma-ray emissions. • High-resolution 13CO images reveal a giant molecular cloud (~ 78 km/s) at the center of W41--likely associated with W41. • Probably, the first evidence that an old SNR encounters a GMC to produce TeV gamma-rays • New results (Leahy &Tian 2008, AJ): determining distances to the W41/cloud system support that such interaction is physical by analyzing HI and 13CO spectra.

  29. Radio Images of W41/molecular cloud: 13CO map from Galactic Ring Survey: a GMC at the center of W41: MH2~10^5 M0NH2 ~10^22 (cm^-2), no ~ 10^3 (cm^-3) 1420 MHz continuum map 36'x30' in size, F1420=60+/-8 Jy Alpha>=0.43 (330 -1420 MHz) (Fv ~ v^(-alpha)

  30. XMM-NEWTON Observations of W41 The central part of W41 in 1.5-7 keV. A region of enhanced intensity is clearly present coincident with the HESS source, apparently diffuse. Contours of 13CO emissions at 1.2, 1.4, 1.8 and 2.1k. An EPIC-pn intensity image in 0.3-1.5 keV. 15 point-like sources are detected also. Red circle represents HESS J1834-087; small green circle illustrates the region for x-ray spectrum.

  31. W41/CO cloud physical interaction Two nearby CO features: at ~77 km/s and ~95 km/s • The maximum velocity of HI absorption:~78 km/s. No absorption at ~95 km/s.

  32. HI+13CO observations: constrain distance to Kes 67; a GMC at 20km/s is physically adjoining with the SNR. ROSAT PSPC: a diffuse X-ray feature apparently associated with part of the radio shell of the SNR. New 13CO observation: clear morphological agreement between the SNR and an adjoining cloud; broadened profile seen in the 13CO emission spectrum. There likely exists a physical interaction! 一个正与临近大CO分子云相互作用的超新星遗迹 G18.8+0.3 Tian, Leahy & Wang, 2007, A&A, 474, 541 • Previous observations (12CO + HI + OH, Dubner et al. 1996, AJ, 111, 1304; 2004 A&A, 426, 201): • 1. Morphological agreement between one 12CO clump and the SNR shock front. • 2. Detection of high line rates 12CO(2-1)/12CO(1-0) in a clump. • A conclusion: a possible interaction between SN shock and an adjoining molecular cloud

  33. Radio and X-ray images of Kes 67 HI Image at 18.3 km/s 1420 MHz image ROSAT PSPC image (0.5-2.4 kev) CO image at 19.8 km/s

  34. HI and 13CO spectra 1.The largest velocity absorption feature at the tangent point gives a lower distance limit of 7.6 kpc. 2. Absence of absorption at negative velocities gives upper limit of 15.2 kpc. 3. The broadened profile at ~20 km/s in the 13CO spectrum indicates a likely SNR/CO cloud interaction and gives a distance of ~12 kpc. Tangent point ~20 km/s

  35. Summary • Using HI+13CO spectra determine distances to seven SNR/PSR/HESS systems: Kes 75~ 6 kpc; Kes 69 ~5.5 kpc, Kes 7--7.5-9.4 kpc, W41--3.9-4.5 kpc, Kes 67~12 kpc, G21.5-0.9--4.4-4.8 kpc, G353.6-0.7~3.2 kpc • Some values differ greatly from previously published values, partly because our methods resolve the near/far distance ambiguity, partly due to better discrimination against HI emission differences in background spectra. • Determining distances to SNR/Cloud/TeV HESS source systems help to trace Galactic CRs origin.

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