1. Cosmic Explosions in the Universe Poonam Chandra Royal Military College of Canada 13 th Sept 2011 Poonam Chandra Page # 1

2.  Universe is 14 billion years old.  Our sun is 5 billion years old.  Universe is 14 billion years old.  Our sun is 5 billion years old. Supernovae and Gamma ray bursts explosions lasting fraction of a second to few seconds. 11-09-13Poonam Chandra2

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4. Supernovae & Gamma Ray Bursts: Most powerful explosions Energy 10 51 ergs. This is 10 29 times more than an atmospheric nuclear bomb explosion. One supernova can shine brighter than the whole galaxy consisting of 200 billion stars. As much energy as the Sun will emit in 5 billion years. Gamma ray bursts are 100 times more powerful than the supernovae. Energy 10 51 ergs. This is 10 29 times more than an atmospheric nuclear bomb explosion. One supernova can shine brighter than the whole galaxy consisting of 200 billion stars. As much energy as the Sun will emit in 5 billion years. Gamma ray bursts are 100 times more powerful than the supernovae. 11-09-13Poonam Chandra4

5. In universe 8 new supernovae explode every second. 11-09-13

6. On our Earth, roughly 1 GRB is detected everyday. 11-09-13

7. DEATH OF MASSIVE STARS 11-09-13Poonam Chandra7

8. Evolution of stars 11-09-13Poonam Chandra8

9. Nuclear reactions inside a heavy star 11-09-13Poonam Chandra9

10. M >8 M sun : core collapse supernovae Burns until Iron core is form at the center Gravitational collapse First implosion (increasing density and temperature at the center) Implosion turns into explosion Neutron star remnant at the centre. Explosion with 10 53 ergs energy 99% in neutrinos and 1 % in Electromagnetic Burns until Iron core is form at the center Gravitational collapse First implosion (increasing density and temperature at the center) Implosion turns into explosion Neutron star remnant at the centre. Explosion with 10 53 ergs energy 99% in neutrinos and 1 % in Electromagnetic 11-09-13Poonam Chandra10

11. M > 30 M sun : Gamma Ray Bursts Forms black hole at the center Rapidly rotating massive star collapses into the black hole. Accretion disk around the black hole creates jets Some GRBs associated with supernovae (GRB980425/SN1998bw, GRB030329/SN2003dh etc.) These GRBs last for few seconds Afterglow lasts for longer duration in lower energy bands. Forms black hole at the center Rapidly rotating massive star collapses into the black hole. Accretion disk around the black hole creates jets Some GRBs associated with supernovae (GRB980425/SN1998bw, GRB030329/SN2003dh etc.) These GRBs last for few seconds Afterglow lasts for longer duration in lower energy bands. 11-09-13Poonam Chandra11

12. 8M Θ ≤ M ≤ 30M Θ Supernova M ≥ 30M Θ Gamma Ray Burst 11-09-13Poonam Chandra12

13. Gravitational Collapse Supernovae/ GRBs 11-09-13Poonam Chandra13

14. On our Earth, roughly 1 GRB is detected everyday. 11-09-13

15. 4-8 M sun : Thermonuclear supernovae 4-8 Massive star: Burning until Carbon Makes Carbon-Oxygen white dwarf White Dwarf in binary companion accretes mass Mass reaches Chandrashekhar mass Core reaches ignition temperature for Carbon Merges with the binary, exceed Chandrasekhar mass Begins to collapse. Nuclear fusion sets Explosion by runaway reaction – Carbon detonation Nothing remains at the center Energy of 10 51 ergs comes out Standard candles, geometry of the Universe 4-8 Massive star: Burning until Carbon Makes Carbon-Oxygen white dwarf White Dwarf in binary companion accretes mass Mass reaches Chandrashekhar mass Core reaches ignition temperature for Carbon Merges with the binary, exceed Chandrasekhar mass Begins to collapse. Nuclear fusion sets Explosion by runaway reaction – Carbon detonation Nothing remains at the center Energy of 10 51 ergs comes out Standard candles, geometry of the Universe 11-09-13Poonam Chandra15

16. Short Hard Bursts Neutron stars or black holes formed during end stages of massive stars Merger of two neutron stars or a black hole and a neutron star colliding Less energetic than collapsar GRBs Duration less than < 2 seconds. Neutron stars or black holes formed during end stages of massive stars Merger of two neutron stars or a black hole and a neutron star colliding Less energetic than collapsar GRBs Duration less than < 2 seconds. 11-09-13Poonam Chandra16

17. WHY SUPERNOVAE???????? 11-09-13Poonam Chandra17

18. 11-09-13 BIG BANG 75% HYDROGEN25% HELIUM HEAVY ELEMENTS???? Poonam Chandra18

19. Nuclear reactions inside a heavy star 11-09-13Poonam Chandra19

20. Supernovae: seeds of life Calcium in our bones Oxygen we breathe Iron, Aluminium in our cars 11-09-13Poonam Chandra20

21. Environment around massive stars Interaction of the ejected material from the supernvae and GRBs with their surrounding circumstellar medium and study them in multiwavebands. 11-09-13Poonam Chandra21 CIRCUMSTELLAR INTERACTION

22. The Sun 11-09-13Poonam Chandra22

23. Shock Formation in Supernovae: Blast wave shock : Ejecta expansion speed is much higher than sound speed. Shocked Circumstellar Medium: Interaction of blast wave with CSM. CSM is accelerated, compressed, heated and shocked. Reverse Shock Formation: Due to deceleration of shocked ejecta around contact discontinuity as shocked CSM pushes back on the ejecta. 11-09-13Poonam Chandra23

24. Circumstellar interaction CS wind Explosion center Reverse Shock Forward Shock Ejecta 11-09-13Poonam Chandra24

25. ELECTROMAGNETIC SPECTRUM 11-09-13Poonam Chandra25

26. Multiwaveband Study Radio: circumstellar medium characteristics X-ray: Shock temperature, ejecta structure. Optical: Temporal evolution, chemical composition, explosion, distance Infrared: circumstellar dust nebula surrounding SN. 11-09-13Poonam Chandra26

27. Radio emission from Supernovae: Synchrotron non- thermal emission of relativistic electrons in the presence of high magnetic field. X-ray emission from Supernovae: Both thermal and non-thermal emission from the region lying between optical and radio photospheres. Interaction of Supernova ejecta with CSM gives rise to radio and X-ray emission 11-09-13Poonam Chandra27

28. RADIO TELESCOPES (Expanded) Very Large Array Giant Metrewave Radio Telescope 11-09-13

29. ROSAT Swift ASCA Chandra XMM 11-09-13Poonam Chandra29

30. X-ray telescopes XMM 11-09-13Poonam Chandra30

31. Various types of supernovae Classification H (Type II) No H (Type I) Si (Type Ia) No Si (6150A o ) He (Type Ib) No He (Type Ic) IIPIILIIN 11-09-13Poonam Chandra31

32. Suggested by Schlegel 1990. Most diverse class of supernovae. Unusual optical characteristics: – Very high bolometric and Ha luminosities – Ha emission, a narrow peak sitting atop of broad emission – Slow evolution and blue spectral continuum Late infrared excess Indicative of dense circumstellar medium. 11-09-13Poonam Chandra32

33. Peak radio and X-ray luminosities 11-09-13Poonam Chandra33

34. Multiwaveband campaign to understand Type IIn supernovae Observe all the Type IIN supernovae with the Very Large Array within 150 Mpc distance (PI: Chandra). If bright enough, do spectroscopy with XMM- Newton (PI: Chandra). Follow radio bright and/or Swift detected Type IIN supernova with ChandraXO. Get spectroscopy, separate from nearby contamination (PI: Chandra). If detected in radio, follow with Swift-XRT (PI: Soderberg). NIR photometry with PAIRITEL (PI: Soderberg). Observe all the Type IIN supernovae with the Very Large Array within 150 Mpc distance (PI: Chandra). If bright enough, do spectroscopy with XMM- Newton (PI: Chandra). Follow radio bright and/or Swift detected Type IIN supernova with ChandraXO. Get spectroscopy, separate from nearby contamination (PI: Chandra). If detected in radio, follow with Swift-XRT (PI: Soderberg). NIR photometry with PAIRITEL (PI: Soderberg). Chandra, Soderberg, Chevalier, Fransson, Chugai, Nymark 11-09-13Poonam Chandra34

35. VLA observations of Type IIn supernovae 11-09-13Poonam Chandra35

36. Chandra et al. 2011 11-09-13Poonam Chandra36

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38. Radio absorption process. Synchrotron self absorption (SSA): magnetic field, size of the shell. Free-free absorption (FFA): Mass loss rate of the progenitor star. FFA SSA 11-09-13Poonam Chandra38

39. Chandra et al. 2011 11-09-13Poonam Chandra39 Synchrotron Self Absorption Free-free Absorption

40. Chandra et al. 2011 11-09-13Poonam Chandra40

41. Gamma Ray Bursts Meszaros and Rees 1997 11-09-13Poonam Chandra41

42. GRB Missions BATSE BeppoSAX 11-09-13Poonam Chandra42

43. SWIFT AVERAGE REDSHIFT = 2.7 11-09-13Poonam Chandra43

44. 11-09-13Poonam Chandra44 FERMI AGILE

45. Gamma Ray Bursts A big challenge when discovered in 1960s. Gamma-ray signals for just a fraction of seconds to at most few minutes. 11-09-13Poonam Chandra45

46. Gamma Ray Bursts Afterglow Meszaros and Rees 1997 11-09-13Poonam Chandra46

47. Major breakthrough BeppoSAX: first detection of X-ray counterpart of GRB 970228. Optical detection after 20 hours. 11-09-13Poonam Chandra47

48. SWIFT AVERAGE REDSHIFT = 2.7 11-09-13Poonam Chandra48

49. Radio Observations of Gamma Ray Burst afterglows 11-09-13Poonam Chandra49 Very Large Array program to observe Gamma Ray Bursts in radio bands since 1997 Total observed 304 bursts since then Detected 95 bursts i.e. 30% detection rate Detection rate much higher in X-ray band (90%) and optical band (80%) Detecting very far away bursts in radio bands. With Expanded VLA detection rate is increasing See Chandra et al. 2011b for details

50. Multiwaveband modeling Long lived afterglow with powerlaw decays Spectrum broadly consistent with the synchrotron. Measure F m, m, a, c and obtain E k (Kinetic energy), n (density),  e,  b (micro parameters), theta (jet break), p (electron spectral index). 11-09-13Poonam Chandra50

51. Determination of Kinetic Energy for GRB 070125 (Chandra et al. 2008) 11-09-13Poonam Chandra51

52. GRB 090423 X-ray observtions: 73 s after detection Optical observations: 109 s after detection No optical transient. Detection in J band onwards. Photo-z=8.06+/-0.25 Spectral-z=8.23+/-0.08 11-09-13Poonam Chandra52

53. Multiwaveband modeling: (Chandra et al. 2010) 11-09-13Poonam Chandra53

54. Broadband modeling 54 High energy burst exploded in constant density medium. No jet break occurred until day 50. 11-09-13Poonam Chandra

55. Previous high redshift GRB 050904 z=6.26 Afterglow Properties – – GRB 050904 (z=6.26). Both are hyper-energetic (>10 51 erg) but they exploded in very different environments. (in situ n=600 cm -3 for GRB 050904) – Large energy predicted for Pop III. Not unique. – Low, constant density predicted for Pop III. Not unique. – No predictions for θ j, ε B, ε e & p –Reverse shock detection in both GRBs 11-09-13Poonam Chandra55

56. A seismic shift in radio afterglow studies The VLA got a makeover! More bandwidth, better receivers, frequency coverage 20-fold increase in sensitivity Capabilities started in 2010 11-09-13Poonam Chandra56

57. Future of GRB Physics 11-09-13Poonam Chandra57

58. Atacama Large Millimeter Array 58 11-09-13Poonam Chandra

59. Future: Atacama Large Millimeter Array (ALMA) Accurate determination of kinetic energy 11-09-13Poonam Chandra59

60. Collaborators: Dale Frail (NRAO) Roger Chevalier (Univ. Virginia) Shri Kulkarni (Caltech) Alicia Soderberg (Princeton) Brad Cenko (Berkeley) Claes Fransson (Stockholm Observatory) Nikolai Chugai (Moscow University) 11-09-13Poonam Chandra60