超新星遺跡和相關聯(lián)天體的21厘米中性氫觀測-北京大學

1、超新星遺跡的射電巡天觀測和甚高能伽瑪射線源研究,田文武 2008年6月5日在北京大學的報告,射電天文的重大發(fā)現(xiàn),1951年，星際HI譜線1965年，3K微波背景1967年，脈沖星, VLBI1968年，星際分子1971年，視超光速運動1974年，脈沖雙星/引力波….,概要,21厘米中

2、性氫原子(HI)譜線銀道面巡天簡介及建立新方法(Tian & Leahy方法)獲得可信賴的超新星遺跡和相關聯(lián)天體的距離(或范圍)超新星遺跡和分子云的相互作用導致很多天體物理現(xiàn)象,如加速帶電粒子到相對論能量, 產(chǎn)生可以觀測到的TeV伽瑪射線. 測定天體的距離可以直接檢驗超新星遺跡是河內宇宙線粒子起源處的合理性實例: 四個超新星遺跡和TeV源相關聯(lián)系統(tǒng):G29.7-0.3/PSR J1846-0258/HESS J1846-0

3、29, G21.5-0.9 /PSR J1833-1034/HESS J1833-105, G23.3-0.3/HESS 1834-087,G353.6-0.7/HESS J1731-347; 一個含異常X-光線脈沖的年青超新星遺跡 G27.4+0.0 /AXP 1E1841+045;一個正與臨近大CO分子云相互作用的超新星遺跡 G18.8+0.3; 及一個產(chǎn)生1720兆赫茲OH脈澤輻射的年青超新星遺跡 G21.8-0.6.,21-c

4、m HI observations in the Milky Way disk,,,,,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=-40d),1420 MHz

5、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 channelShort-spa

6、cing information for the H I line emission from observations with the 100m Green Bank Telescope,1420MHz and 13CO data ( + X-ray data),,T,An example to build absorption spectra to Kes 75 (a TeV source),1420 MHz map from V

7、LA D-array observations.,21 cm HI map from VLA+GBT observations with contours (28 40 60 100 k) overlaid,Ton (v)-Toff(v)=(Ts-Tbg)(1-e^{-tau})solid-line box ---> Ton(v) Annulus background Toff(v),,,,HI+CO13 spectra sho

8、w 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,,,,,Rotation curve of Milky Way stays flat with distance,,,,,,Calculated ra

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

10、city,The long-standing puzzle on Kes 75/PSR J1846-0258 is resolved (Leahy & Tian, 2008, A&A, 480, L25. 已7次獨立引用, 改寫了前面的結果:Becker & Helfand, 1984, ApJ, 283, 154,被引用36次),1. Significant distance revision from ~1

11、9 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)

12、 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

13、, much higher ratio of the pulsar-plus-nebula luminosity to spin-down luminosity.,,,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 i

14、nhomogeneous.3.The HI feature at 84 km/s is at the far distanceConclusion: Kes 73 is in front of the HI at 84 km/s, but beyond the tangent point.,,HI+CO spectra confirm the above conclusion.The CO cloud (~89 km/s

15、) 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

16、500 to 1000yr, the AXP has a larger 50% X-ray luminosity.Tian & Leahy, ApJ, 2008, 677, 692,,~84 km/s,,~110 km/s tangent point,,~89 km/s,,SNR/Cloud interaction,1. Detection of high energy gamma ray and non-thermal X-

17、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

18、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

19、 system by HI+CO obs.,Schematic of an expanding SNR interacting with an adjacent molecular cloud (Wardle & Yusef-Zadeh 2002),Emit TeV gamma-rays,,The distance to Kes 69 and G21.5-0.9,New VLA 14

20、20 MHz map,,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.,,,X-ray (contour --ROSAT PSPC)+radio (grey from NVSS) image from Yusef-Zad

21、eh et al. (2003, ApJ, 585, 319),Old OH maser at69.3km/sNew OHMaser at~84km/s,,,1,G21.5-0.9,pwn,Kes 69,HI spectrum: max velocity of absorption ~86 km/s; HI emission feature at 113 km/s with no respective absorption.C

22、O 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.Conclu

23、sions: distance of ~5.5 kpc to Kes 69, and physical interaction between Kes 69 and adjoining cloud.,,,,,,y,GBT map,,(from Jack Hewitt),VLA D-Array,Integrated1720 MHz line intensity,OH maser Vo=84 km/s,Spitzer image,,,G21

24、.5-0.9 and PMN J1832-1035,,,,1. The highest absorption velocity~66 km/s, no absorption at~71 and 86 km/s2. 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

25、/s),http://www.mppmu.mpg.de/~rwagner.sources,The thick-solid line shows the total non- thermal flux. Hadronic emissions are Pion-decay gamma- rays (thin-solid), synchrotron (dot-dashed) and bremsstrahlung emi

26、ssion (short-and- long dashed) from secondary electrons produced by charged pion. Leptonic emissions are synchrotron (long- dashed), inverse-Compton (dotted) and bremsstrahlung (short-dashed

27、) emission by primary electrons.,vFv spectrum of a young SNR with an age 10^3 yrs,an old SNR case,an old SNR-a GMC,an illuminated GMC,,,,,,,,,The HESS J1731-347 image ( Aharonian et al. 2008, A&A, 477, 353); C

28、ontours 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

29、^{-Г}),Г=2.26±0.10,,Two SNR and TeV HESS source Systems,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)

30、 (2007, ApJL, 657, 25. 已13次引用, 其中9次獨立引用):,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

31、1, ApJL, 679, 85) 1. National Astronomical Observatories of China, CAS, China2. Department of Physics & Astronomy, Uni. of Calgary, Canada3. Astronomy Department, Uni. of California-Berkeley, USA4. Department

32、of Astronomy, Uni. of Massachusetts, USA,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 o

33、f < 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),X-ray and

34、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 ~ 5Right: 8 micro mid-infrared image, centred at l=353.5, b=-0.65 from the

35、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!,,,,,,Spectral Index of G353.6-0.7,Azim

36、uthally averaged flux over the low half of G353.6-0.7 as a function of radius from the center of the remnant.,Total flux density estimayes of 2.2±0.9 Jy at 1420 MHz and 1.4±0.3 Jy at 5 GHz (Parkes observations,

37、 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 reli

38、able flux density.,ACTA+Parkes image. The ring shows the boundary of SNR G353.6-0.7.,,Distance to G353.6-0.7Too faint to obtain HI absorption spectrum of the new SNR. HII region G353.42-0.37 is adjacent to the SNR. The

39、 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

40、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

41、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.,Overlapping Radio (grey)+X-ray (red)+gamma-ray (green) images of G353.6-0.

42、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

43、revealed by the 12CO column density increasing towards the Galactic plane.,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

44、 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),

45、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 expecte

46、d to emit few thermal X-rays from the high T gas heated by the fast-enough shock,W41/HESS J1834-087,XMM-Newton observations show diffuse X-ray emission within the HESS source J1834-087--- this suggests an association bet

47、ween 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 encounte

48、rs 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.,,Radio Images of W41

49、/molecular cloud:,1420 MHz continuum map36'x30' in size, F1420=60+/-8 JyAlpha>=0.43 (330 -1420 MHz)(Fv ~ v^(-alpha),,13CO map from Galactic Ring Survey: a GMC at the center of W41: MH2~10^5 M0 NH2 ~10^22

50、(cm^-2), no ~ 10^3 (cm^-3),XMM-NEWTON Observations of W41,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 regi

51、on for x-ray spectrum.,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

52、.,W41/CO cloud physical interaction,The maximum velocity of HI absorption:~78 km/s. No absorption at ~95 km/s.,Two nearby CO features: at ~77 km/s and ~95 km/s,,,,一個正與臨近大CO分子云相互作用的超新星遺跡 G18.8+0.3 Tian, Leahy & Wan

53、g, 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

54、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,HI+13CO observations: constrain distance to Kes 67; a GMC at 20km/s is physically adj

55、oining 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; broad

56、ened profile seen in the 13CO emission spectrum.There likely exists a physical interaction!,Radio and X-ray images of Kes 67,,,1420 MHz image,HI Image at 18.3 km/s,CO image at 19.8 km/s,ROSAT PSPC image (0.5-2.4 kev),HI

57、 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 pr

58、ofile at ~20 km/s in the 13CO spectrum indicates a likely SNR/CO cloud interaction and gives a distance of ~12 kpc.,,~20 km/s,Tangent point,,Summary,Using HI+13CO spectra determine distances to seven SNR/PSR/HESS syst

59、ems: 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 metho

60、ds 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 CR