1. Pair-instability supernovae From Woosley et al. (2002, 2007) Woosley Lecture 19

2. Most distant explosion smashes previous record NASA NEWS RELEASE Posted: September 12, 2005 http://www.spaceflightnow.com/news/n0509/12swift/ http://www.spaceflightnow.com/news/n0509/12swift/ This powerful burst was detected September 4. It marks the death of a massive star and the birth of a black hole. It comes from an era soon after stars and galaxies first formed, about 500 million to 1 billion years after the Big Bang. The September 4 burst, named GRB 050904, has a redshift of 6.29, which translates to a distance of about 13 billion light-years from Earth. The Universe is thought to be 13.7 billion years old. The previous most distant gamma-ray burst had a redshift of 4.5. The most distant quasar known is at a redshift of 6.4. This burst was also very long, lasting more than 200 seconds, whereas most bursts last only about 10 seconds. The detection of this burst confirms that massive stars mingled with the oldest quasars.

3. På fredag kommer Troels Haugbølle på besøg fra København. Nogle af jer kender ham sikkert allerede som PhD studerende hos Aake. Han har arbejdet med simuleringer af gamma-ray bursts o.l. I forbindelse med vores "astropartikel" frokostmøde (12-13 i 520-731) holder han et 15-20 minutters foredrag om sine simuleringer, hvis nogle af jer skulle være interesserede. Alle er naturligvis også mere end velkomne til at komme til møderne under alle omstændigheder. De er meget uformelle, og består normalt i, at en eller to medbringer en ny artikel, som de synes ser spændende ud.

10. (Fryer & Kalogera 2001; see also: Burrows 1999)

14. Ejected “metals”

27. Mass Loss in Very Massive Primordial Stars Negligible line-driven winds (mass loss ~ metallicity 1/2 ) (Kudritzki 2002) No opacity-driven pulsations (no metals) Continuum-driven winds likely small contribution Epsilon mechanism inefficient in metal-free stars below ~1000 M  (Baraffe, Heger & Woosley 2000) from pulsational analysis we estimate upper limits: –120solar masses: <0.2 % –300solar masses: <3.0 % –500solar masses: <5.0 % –1000solar masses: <12.0 % during central hydrogen burning Red Super Giant pulsations could lead to significant mass loss during helium burning for stars above ~500 M 

29. 8 – 11 M ¯ : uncertain situation ? M < M 1 ' 8 M ¯ : No C ignition M > M 2 ' 12 M ¯ : Full nondegenerate burning In between: ???? Degenerate off-centre ignition Possibly O-Ne-(Mg?) white dwarfs (after some additional mass loss) With sufficient O-Ne core mass: continued burning and core collapse

30. Pair-instability supernovae He burning collapse and energy release  +  ! e + + e - :  1 < 4/3 Dynamical collapse, bounce, explosive burning (for M < 260 M ¯ ) Dynamical collapse directly to black hole (for M > 260 M ¯ ) Pop. III stars, no mass loss

31. Possibly observed: SN 2006gy Smith et al. (2007; ApJ 666, 1116)

32. Can very massive stars retain their mass even today? The Pistol Star Galactic star Extremely high mass loss rate Initial mass: 150 (?) Will die as much less massive object

33. Pair instability  Helium core mostly convective and radiation a large part of the total pressure.  ~ 4/3. Contracts and heats up after helium burning. Ignites carbon burning radiatively  Above 1 x 10 9 K, pair neutrinos accelerate evolution. Contraction continues. Pair concentration increases. Energy goes into rest mass of pairs rather than increasing pressure,  < 4/3. Contraction accelerates.  Oxygen and (off-center) carbon burn explosively liberating a large amount of energy. At higher mass silicon burns to 56 Ni  The star completely, or partially explodes Barkat, Rakavy and Sack (1967) (M  > 40 solar masses)

34. Helium stars, M He = 2.2 – 8 Nomoto and Hasimoto (1986; Prog. Part. Nucl. Phys. 17, 267)

35. Pair-Instability Supernovae Many studies in literature since more than 3 decades, e.g., Rakavey, Shaviv, & Zinamon (1967) Bond, Anett, & Carr (1984) Glatzel, Fricke, & El Eid (1985) Woosley (1986) Some recent calculations: Umeda & Nomoto 2001 Heger & Woosley 2002 Pulsational Pair Supernovae Pair instability Supernovae Black holes Rotation reduces these mass limits! Mass loss alters them. ¯ ¯ ¯ ¯ ¯ ¯

37. Light curves of pair instability supernovae in their restframe

38. Compared with a typical SN Ia (red SN 2001el), a Type Iip (blue. SN 1999em) and the hypernova SN 2006gy (green)

39. Red-shifted light curve of a bright pair-instability SN

40. Pulsational Pair Instability Supernovae

42. Pulsations Woosley et al. (2007; Nature 450, 390)

43. 238 million light years away Smith et al. (2007; ApJ 666, 1116)

45. Onset of instability Woosley et al. (2007; Nature 450, 390)

46. At end of first pulse Woosley et al. (2007; Nature 450, 390)

47. After 2 nd pulse Woosley et al. (2007; Nature 450, 390)

48. At final point Woosley et al. (2007; Nature 450, 390)

49. Velocity and enclosed mass after second mass ejection - 110 solar mass model (74.6 at explosion) Shock heating Woosley et al. (2007; Nature 450, 390)

50. Light curves of the two outbursts (110 solar mass model) Woosley et al. (2007; Nature 450, 390) 200619992012

51. Absolute R-band magnitudes of the 110 solar mass model compared with obsevations of “hypernova” SN 2006gy. Instabilities will smooth these 1 D calculations. The brighter curve assumed twice the velocity for all ejecta. (7.2 x 10 50 erg becomes 2.9 x 10 51 erg) Woosley et al. (2007; Nature 450, 390)