Light-Echo Spectrum revealed types of Tycho Brahes’s 1572 & Cas A SNe

1. Light-Echo Spectrum revealed types of Tycho Brahes’s 1572 & Cas A SNe Tomonori Usuda (SUBARU) Oliver Krause, Stephan M. Birkmann, Miwa Goto (MPIA), Takashi Hattori (Subaru Telescope), Masaomi Tanaka, Ken’ichi Nomoto (Univ. of Tokyo), George H. Rieke, Karl A. Misselt (Steward Observatory) Cas A Blue：X-ray (CXO) Green：Optical (HST) Red：Mid-IR (SST) Tycho BGY：X-ray (CXO) Red：Mid-IR (SST) White: Near-IR

2. Outline • Review Galactic Supernova Remnants (SNRs) & Historical Supernovae (SNe) • Cassiopeia A (Cas A) • Tycho Brahe’s SN 1572 • Special Observation Tool: Light echo • Case 1: Cas A – Observation / Results • Case 2: Tycho – Observation / Results • Future plans & Conclusion

3. Review Galactic Supernova? Tycho Brahe RCW86 Crab G11.2 Cassiopeia A Kepler G1.9

4. Cassiopeia A • Second youngest SNR known in our Galaxy (cf. G1.9+0.3 discovered by CXO in 05/13/2008) • Well known & studied SNR • It might be appeared around 1680, however no historic records (e.g., SN1054: Crab by Teika Fujiwara『Meigetsuki』) Q1: What kind of supernova explosion? Q2: Why it was not witnessed in 17th century?

5. Tycho Brahes’s 1572 Supernova • Well known & studied SNR • Danish astronomer Tycho Brahe found very bright `new star’ in the constellation of Cassiopeia on the evening of 11th of November in 1572. He had observed its brightness, color, and proper motion until March in 1574. • In 20th century, the `new star’ = A supernova • Brightness & Color light curve ←→ Theoretical Model of SN • X-ray observations → Spherical symmetry of metal abundance • Radio etc. → No pulser • Optical → Candidate of surviving binary companion of SN 1572 Q: Is SN 1572 really type Ia Supernova? → Classified by only optical spectrum ``Astronomie Populaire” by Camille Flammarion (Paris, 1884)

6. How we can solve the mysteries on the past?! Light Echo can go back to the past rewind time

7. Light echoes – Rewinding time to historic SN explosions 5 seconds 2800 ft (850m) Echo (sound)

8. Light echoes – Rewinding time to historic SN explosions Blue: Light of SN explosion arrived at Earth in 1572. Red : Scattered-light echo by dust arrives now.

9. Light echoes – Rewinding time to historic SN explosions "As Professor J.H. Oort has pointed out to us, the illumination of surrounding clouds might become a spectacular phenomenon in the case of galactic supernovae. The search for the illumination of galactic clouds by past suspected supernovae such as Tycho's star and the stars which gave rise to the Crab Nebula and perhaps other nebulosities presents an interesting problem”. By Zwicky Rev. Mod. Phys. 12, 66 (1940) SN 1987A Suntzeff

10. Light echoes – Rewinding time to historic SN explosions • However… Observation of Light echo is very difficult. • Very Faint (Light echo became fainter and fainter day by day) • → Even though can detect light echo, difficult to take its spectrum • When? Where? How bright? • → Just wait and Searching Dust cloud SN 1987A SN Echo geometry Suntzeff

11. Observations • When? Where? How bright? → Monitoring and ToO (Target of Opportunity) → International collaborations with MPIA • Calar Alto 2.2m & 3.5m + Wide Optical Camera PI: Oliver Krause (MPIA) → Monitoring & Looking for optical light echo • Subaru Telescope 8.3m + FOCAS PI: Tomonori Usuda (Subaru/NAOJ) →Imaging: Re-confirmation of light echo Spectroscopy: Take its optical spectrum

12. Case 1: Cassiopeia A

13. Associated scattered light echo by Calar Alto 2.2m & SUBARU 8.2m October 9, 2007 Spectro-scopy SUBARU + FOCAS Detect optical light echo! R = 23.4 mag / arcsec2

14. Results: Spectroscopy Went back in time to detect light that originally arrived at Earth more than 330 years ago. He I Hα He I • dl=2.4nm (ll=476~989 nm) / Av=3.1 mag • Exp time=5.5 hours • Spectral features of Supernovae • Broad line width (17,000 km/s) / P-Cygni profile • Strong H & He emission lines

15. Results

16. Comparison with the proto-typicaltype IIb SN 1993J

17. Results

18. Comparison with the proto-typicaltype IIb SN 1993J Cas A was a type IIb SN & Red Supergiant (13-20 Solar Mass) as progenitor star

19. Case 2: Tycho

20. Results: Imaging N E Shift Slit position 30” Center of SNR Center of SNR a: Calar Alto 2.2m b: Subaru＋FOCAS Back box: Previous light echo position in 2006 Red+ mark: Brightest position (R=23.5 mag) → Slit position (2.8”x2.0”) for spectroscopy by FOCAS → Subtraction of sky & nebulosity lines

21. Results: Spectroscopy He Hα Si Optical spectrum of the light that originally arrived at Earth in 1572 • dl=2.4nm (ll=380~920 nm) / Av=2.4 mag • Exp time=2.5 hours (Red) + 1.5 hours (Blue) • Remarkable spectral features of Supernovae • Broad line width (9,000~12,000 km/s) • No H & He lines • Strong absorption lines of Si and Fe

22. Results

23. Results: Spectroscopy He Hα Si • Spectral features of Supernovae • Broad line width (9,000~12,000 km/s) • No H & He lines • Strong absorption lines of Si and Fe • → Type Ia Supernova

24. Results

25. Various type Ia Supernova Type Ia SN = Cosmological distance indicator → Discovery of the accelerated expansion of Universe Luminosity is NOT uniform! Normal Type Ia SN Subluminous Overluminous Si Si Ca Fe Ni Si Ca Fe Ni Si Ca Fe Ni Reason why its variety of luminosity? → Accurate cosmological distance indicator?

26. Results: Spectroscopy Overluminous type Ia Normal type Ia Subluminous type Ia Tycho was normal type Ia SN

27. Unique opportunity to test theories of SN Explosion mechanism d=100 Mpc 10 arcmin Point source SNe in extra-galaxies Tycho’s SNR d = 3.8 kpc

28. Spatial Resolved Investigation HighVelocity Ca II

29. For the first time, spectra of historical Galactic supernovae (Cas A & Tycho) have been secured. Cas A: Type IIb SN & Red Supergiant (13~20 Mo) Why Cas A was not witnessed in 17th century Type IIb SN fade away quickly, poor weather of several days, higher extinction (Av~8), peak brightness (~3 mag) Tycho: Normal type Ia SN & d=3.4kpc (cf. 2.3~2.8 kpc) Light echoesat different position angles from the source →3D aspect → Spatial structure of SN outburst mechanism Conclusions

30. Mahalo !