Supernova 1987A at 25 years

1. Supernova 1987A at 25 years

2. TOPICS • Highlights of the past 25 years • Outstanding mysteries and surprises • What we can expect to learn, sooner and later

3. Supernova Energy Sources • Core collapse: E ~ GM2/R ~ 0.1 Mc2 ~ 1053 ergsNeutrinos: t ~ 10s • Radioactivity: 0.07 M8[56Ni g56Co g56Fe] ~ 1049 ergs.Light: t ~ 3 months • Kinetic energy: ~ 10 M8, Vexpansion ~ 3000 km/s ~ 1051 ergs ~ 1% core collapse. X-rays: t ~ decades - centuries.

4. Neutrino signal (1053 ergs) a a neutron star formed (I think!)

5. 56Co 57Co 44Ti Optical Light (1049 ergs): driven by radioactivity

6. X-rays (1051 ergs): from kinetic energy (crash)

7. What we have learned: the interior

9. RADIOACTIVE DEBRIS

11. IR nebular spectrum: • CO bands a interior T < 3000 K @ 260 days; now < 300 K • Strong, optically thick FIR lines of [FeII], [CoII] a newly synthesized Fe must occupy ~ 50% of volume of glowing interior: “nickel bubbles” due to foaming action driven by radioactive heating Fe, Co, Ni Dust C, O, Si, S H, He

12. Interior Dust Formation • 400 – 700 d: bolometric luminosity shifted from optical to FIR; • Red sides of nebular emission lines vanished • Visible glow of interior comes mostly from near side. • Morphology determined largely by dust distribution. • Dust obscures central object. • Southern extension is in equatorial plane

13. What we have learned: the exterior

14. Crash: birth of SNR1987A Time-lapse movie of HST images 1994 - 2006

15. HST - Optical March 2011 ATCA 9 GHz 2009 Chandra 0.5 – 2 keV 2009

16. Light Curves of CS Ring Optical (HST) Radio, IR, X-ray

17. RADIOACTIVE DEBRIS

19. Motion of optical (HST) hotspots

20. Expansion of X-ray ring (Racusin et al) and radio shell (Ng et al)

21. Heating of debris by external X-rays

22. Hubble observations of the reverse shock: an adventure in spectroscopy

23. Ha

24. Line emission and impact ionization at reverse shock surface H +pg2p +e H*gH +hn Ha, Lya Dn/n=v;/c H +pgH*+p

25. Luminosities of Ha and Lya Each hydrogen atom crossing RS will produce, on average: Rexc(2p)/Rion = 1 Lya Rexc(Ha)/Rion = 0.2 Ha Integrated luminosity of Haamass flux of H atoms across RS.

26. z To observer Surfaces of constant Doppler shift are planar sections of the supernova debris Dl/lo = v/c where v = H0z and H0 = 1/t Dl

27. STIS Ha Observations Jan 30, 2010

28. Doppler Mapping of Ha Emission from RS Surface

29. Lyman-a

30. Ha 2010/2004

31. Lya vs. Ha • Reverse shock: photon emission ratio Lya/Ha should be 5/1 • Ratio should be independent of Doppler velocity • But actual ratio varies from 10/1 to 200/1 ! • Line profiles completely different: unlike Ha, Lya is not confined to surface; appears to come from interior • (We should have realized this in 2004): There must be another mechanism to account for most Lyaemission! • Two possiblities (maybe both): • 1. Resonant scattering of narrow Lya from the ring by HI in debris • 2. Heating of HI in debris by external X-rays

32. Resonance Scattering of Lya by Supernova Debris Source of Lya is nearly stationary emission from hotspots in circumstellar ring Model requires: aSufficient luminosity of Lya photons from hotspots to account for broad Lya; aSufficient optical depth of SN envelope in damping wings of Lya @ 5000 km/s.

33. New (March 2011) results from • Cosmic Origins Spectrograph • COS compared to STIS: • UV only • Much (60x) better sensitivity & S/N • But poor spatial resolution

36. Ly a CIV1550 He II 1640 NV 1240 H (2S a 1S) continuum from hotspots

37. Broad NV1239,1242 Emission from Reverse Shock NV Borkowski, Blondin, & McCray 1997 Reverse shock excitation: Ha/H = [Rexc(Ha) (12.1 eV)]/Rion(H) (13.6 eV) = 0.2 NV1240/N = [Rexc(1240) (10.1 eV)]/Rion(N+4) (98 eV) = 500!

38. Carbon/Nitrogen Ratio • Standard cosmic abundance ratio: C/N = 4.1 • Narrow UV emission lines from ring a C/N = 0.11 • Broad UV emission lines from RSa C/N = 0.05 • Interpretation: • nuclear burning (CNO bi-cycle) converts C, O into N. This explains decreased C/N ratio in ring. • Further decrease of C/N ratio seen in RS a either: (a) stratification of C/N ratio in outer envelope of progenitor; or (b) continued nucleosynthesis subsequent to ejection of ring.

39. The Future: what can we hope to learn? • What is the compact object? • What made the triple ring system? • How (where) are the relativistic electrons accelerated? • What is the distribution of newly-synthesized elements in the SN interior

40. Compact object? – not a clue! Bolometric luminosity < few hundred L8 < 10-3 Crab pulsar The best hope: image compact FIR source with JWST (2018?)

41. Mysteries How (where) are the relativistic electrons accelerated? Image non-thermal radio emission. ALMAwilldo these things: Angular resolution <0.1 arcsec Cycle 0 observations: April 2012

42. New Far Infrared Results from Herschel Telescope 250mm emission has been interpreted as continuum emission from interior dust grains (Matsuura et al 2011). This requires ~ 0.6 solar masses of dust at 18K !!??. Even if CO (2.6 mm) line emission is 1% of dust emission, ALMA will see it. If so, ALMA will provide a 3-d map of the interior CO emitting region.

43. Simulated ALMA Cycle 0 images @ 0.8 mm L: 10 mJY central, 10 mJy ring; R: 3 mJy central, 17 mJy ring

44. HST Cycle 20 (we hope!) STIS: 3-d map of interior debris + RS WFC3 + filters: 2-d images of high-velocity Lya and Ha

45. Thanks to: • Bob Kirshner and SAINTS team • Kevin France • ClaesFransson • Remy Indebetouw • Sangwook Park • and many others

46. Inner debris Reverse Shock VLT broad Ha profile: Fransson et al 2011

48. HeII 1640: analogue of Ha: 1640/Ha = [XHe/XH][Rexc/Rion(He)]/[Rexc/Rion(H)] = [XHe/XH] = 0.21 ✔ But line profiles are different, because He+ can be accelerated in shocked gas.