X-ray Spectroscopy of Classical Novae

Transcription

1 X-ray Spectroscopy of Classical Novae Harvard-Smithsonian CfA Seminar, Dai Takei Rikkyo University

2 2/58 謝辞 (Acknowledgement) セミナーにご招待戴き... for inviting me to the seminar!! ありがとうございます!! Thank you very much...

3 Classical Novae late-type dwarf or giant (IR ~ Optical) white dwarf (X-rays) accretion disc (Optical ~ UV) 3/58

4 4/58

5 5/58 photosphere (Optical (Optical) ~ UV)

6 6/ photosphere (super-soft (Optical ~X-ray) UV)? dust? (Near-IR)

7 1 photosphere (super-soft X-ray) 2 shock (thermal X-ray) 7/58 3 acc. particles? (non-thermal X-ray)

8 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 8/58

9 9/58 Primary Star (White Dwarf) Degenerate star (electron degenerate) - Mass limit : M ch ~ 1.4 M. (Chandrasekhar 1931) Mass-Radius relation - More massive WDs are smaller (Nauenberg 1972) (Light) (Heavy) CO ONe

10 Mechanisms of Classical Novae accretion (H-rich material) accretion (H-rich material) high pressure & temperature at white dwarf surface Mixing? TNR TNR (Light) (Heavy) CO ONe Mixing? 10/58 TNR : Thermo Nuclear Runaway

11 Mechanisms of Classical Novae Hard X-rays Ejecta ( nuclear products + WD material ) O C N Super-Soft X-rays C Nuclear fuel O N Mg Ne Si (Light) (Heavy) CO ONe Mixing...? 11/58

12 12/58 Bode, M. F. 2009, Astronomische Nachrichten, in press. (arxiv: ) Example of Light Curve IR 2 thermal X-ray Radio?? 1 super-soft X-ray 3 Duration non-thermal of the X-ray photospheric? emission is a function of WD mass!!

13 13/58 Point of Views : Classical Novae Hard X-rays (from shock of the ejecta?) - Fast evolution - Weak source - Emission lines in the spectra...? Photospheric Super-Soft X-rays - SSX time scale depends on WD mass - Absorption lines by WD atmosphere Behavior unpredictable - Observations difficult to schedule!!

14 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 14/58

15 A. Road to Super-Novae Quiescent Type Ia Super-Novae? Outburst Mass Increase... 15/58 Mass Loss... WD mass is important!! Increase or Decrease...? Novae (only CO-type) may be Type Ia SN progenitors...? ;

16 16/58 B. Chemical Evolution CNe have a large population in the Universe An outburst scatters heavy elements The composition is derived by X-ray spectra A systematic observation of CNe is the key!! CNe Internal shock with velocity variations X-ray X-rays from Ejecta

17 17/ C. Origin of Cosmic-rays SNR is a major source of galactic cosmic-rays CNe are similar to SNe in many properties Accelerated particles are expected...? SNR (SN 1006) Shock Wave Up Down Diffusive Shock Acceleration

18 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 18/58

19 Observations of CNe 1. Discovery by amateur astronomers - Optical magnitudes and spectra 2. ToO observations with Swift 19/58

20 Swift Multi-wavelength observatory (2004, Nov. 20) High maneuverability Follow-up observations of unpredictable sources Burst Alert Telescope (BAT) X-Ray Telescope (XRT) UltraViolet and Optical Telescope (UVOT) 20/58

21 21/ X-Ray Telescope (XRT)

22 22/58 Page, K. L., et al. 2009, MNRAS, 1602 Example of Swift Pre-Outburst Day 1~12 Day 14~16 Day 21~25 Day 39 Day 53 Day 80~109 Day 112~168

23 Observations of CNe 1. Discovery by amateur astronomers - Optical magnitudes and spectra 2. ToO observations with Swift - X-ray behavior with snapshots 3. Deep spectroscopic study 23/58

24 Chandra X-ray observatory (1999, Jul. 23) The third of NASA Great Observatories Extremely high spatial resolution CCD Imaging Spectrometer (ACIS-I, ACIS-S) Transmission Grating (LETG, METG, HETG) High Resolution Camera (HRC)

25 XMM-Newton X-ray observatory (1999, Dec. 10) Large effective area Photon Imaging Camera (EPIC-MOS, EPIC-PN) Reflection Grating Spectrometer (RGS) Optical Monitor (OM)

26 26/58 Page, K. L., et al. 2009, MNRAS, 1602 Ness, J.-W., 2007 ( Advantages of Grating Swift spectra NVII But, only for bright sources NVI OVIII

27 27/ X-ray Satellite Suzaku ( すざく )

28 28/ Suzaku Detectors of Suzaku XRS XIS HXD (0,1, 2,3) (PIN,GSO) Bandpass 0.2 ~ 12 kev 15 ~ 600 kev Spatial Resolution Not-Working... ~2 arcm. (HPD) N/A Energy Resolution ~130 6 kev ~4.0 kev (PIN) Time Resolution 8 sec 61μsec

29 29/58 Point of Views: Suzaku Advantages of Suzaku... - Wide energy range (0.2 ~ 600 kev) - High sensitivity above 10 kev - Moderately good energy resolution Suzaku is a well-suited tool... - To study line emission of hard X-ray - To examine non-thermal emission We conducted some ToO observations of classical novae using Suzaku!!

30 Observations of CNe 1. Discovery by amateur astronomers - Optical magnitudes and spectra 2. ToO observations with Swift - X-ray behavior with snapshots 3. Deep spectroscopic study - I will show you the results of Suzaku!! 30/58

31 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 31/58

32 32/58 ROSAT ALL-Sky X-ray Background Survey ( kev) Suzaku View : Classical Novae V2491 Cyg ( ) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2010), AN, 331, Takei et al., in prep. U Sco ( ) - Takei et al., in prep. V458 Vul ( ) - Tsujimoto et al. (2009), PASJ, 61, S69 V2672 Oph ( ) - Takei et al., in prep. Suzaku J ( ) - Takei et al. (2008), PASJ, 60, S231

33 33/58 Takei et al. 2008, PASJ, 60, S231 Discovery of Suzaku J Serendipitous discovery of a transient source during a series of routine calibration observations of 1E Position reconstructed; Outside of the XIS FoV.

34 34/58 Takei et al. 2008, PASJ, 60, S231 Suzaku J : Position X-ray Source Optical Source (B0) Error

35 35/58 Takei et al. 2008, PASJ, 60, S231 Suzaku J : Light Curve Decline of the brightness... Suzaku (XIS) Chandra (ACIS) x10 3 Duration is a function of white dwarf mass.

36 36/58 Takei et al. 2008, PASJ, 60, S231 Suzaku J : Spectrum Continuum - Blackbody ( kt ~ 72±2 ev ) WD Atmosphere - O VII Absorption Edge (τ ~ 1.2 ) Small Magellanic Cloud : 60 kpc - L bol ~ erg s -1 - R WD ~ 10 8 cm All these properties indicate that this is a super-soft source. The temperature and duration are functions of the WD mass. - WD Mass ~ 1.2 M.

37 37/58 ROSAT ALL-Sky X-ray Background Survey ( kev) Suzaku View : Classical Novae V2491 Cyg ( ) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2010), AN, 331, Takei et al., in prep. U Sco ( ) - Takei et al., in prep. V458 Vul ( ) - Tsujimoto et al. (2009), PASJ, 61, S69 V2672 Oph ( ) - Takei et al., in prep. Suzaku J ( ) - Takei et al. (2008), PASJ, 60, S231

38 38/58 Classical Nova V458 Vulpeculae - Discovery on 2007 August 8.54 (UT) (Nakano et al. 2007, IAUC, 8861, 2) - Swift detected X-rays on day 70 (Ness et al. 2009, AJ, 137, 4160)

39 39/58 Tsujimoto et al, 2009, PASJ, 61, S69 V458 Vul : Light Curve Day 88

40 40/58 Tsujimoto et al, 2009, PASJ, 61, S69 V458 Vul : Spectrum

41 41/58 ROSAT ALL-Sky X-ray Background Survey ( kev) Suzaku View : Classical Novae V2491 Cyg ( ) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2010), AN, 331, Takei et al., in prep. U Sco ( ) - Takei et al., in prep. V458 Vul ( ) - Tsujimoto et al. (2009), PASJ, 61, S69 V2672 Oph ( ) - Takei et al., in prep. Suzaku J ( ) - Takei et al. (2008), PASJ, 60, S231

42 42/58 Classical Nova V2491 Cygni - Discovery on 2008 April (UT) (Nakano et al. 2008, IAUC, 8934, 1) - Swift detected X-rays on day 5 (Page et al. 2009, MNRAS, submitted.) - XMM-Newton observed on day 40 and 50 (Ness et al. 2009, in prep.; Takei et al. 2009, in prep.) - X-rays were detected in the pre-nova phase (Ibarra et al. 2009, A&A, 497, L5)

43 43/58 The optical data were provided by the variable star observations from the AAVSO International Database and the VSOLJ Observation Database contributed by observers worldwide and used in this research. V2491 Cygni : Light Curve Day 9 Day 29

44 Flux (photons cm -2 s -1 kev -1 ) V2491 Cygni : Spectrum (Day 9) XIS HXD Power-Law (Γ = 0.1) The highest energy Thin-thermal X-rays up Plasma to 70 kev ever detected from a nova!! (Takei et al. 2009, ApJL, 697, 54) 44/58 Energy (kev) Takei et al.,2009, ApJL, 697, 54

45 Discussion Photon X-ray 45/58 Non-thermal particle - Theoretical works (e.g., Tatischeff & Hernanz 2007) - Radio observations (e.g., Rupen et al. 2008) Flat power-law spectrum - Photon Index : Γ= Flux : I(E) E -Γ Electron population - 1 IC or 2 Synchrotron -> Number Index : P Bremsstrahlung -> Number Index : P 1.1 Magnetic Field + Proton - Electron - Electron Electron - X-ray X-ray 1 2 3

46 46/ Standard Acceleration Model Diffusive Shock Acceleration model (P 2.0) (e.g., Blandford & Ostriker 1980, ApJ, 237, 793) Flat population (P 1.1) cannot be explained (Takei et al. 2009, ApJL, 697, L54) SNR (SN 1006) Shock Wave Upstream Downstream Diffusive Shock Acceleration

47 47/58 ROSAT ALL-Sky X-ray Background Survey ( kev) Suzaku View : Classical Novae V2491 Cyg ( ) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2010), AN, 331, Takei et al., in prep. U Sco ( ) - Takei et al., in prep. V458 Vul ( ) - Tsujimoto et al. (2009), PASJ, 61, S69 V2672 Oph ( ) - Takei et al., in prep. Suzaku J ( ) - Takei et al. (2008), PASJ, 60, S231

48 48/58 Classical Nova V2672 Ophiuchi - Discovery on 2009 August (UT) (Nakano et al. 2008, CBET, 1910, 1) - Swift detected X-rays on day 1 (Schwarz et al. 2009, ATel, 2173, 1) - Suzaku observed on days 12 and 22 (Takei et al., in prep.)

49 49/58 The optical data were provided by the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. V2672 Oph : Light Curve Day 12 Day 22

50 50/58 V2672 Oph : X-ray Spectra Spectral Intensive evolution Si emission in the line flare!!!!

51 51/58 ROSAT ALL-Sky X-ray Background Survey ( kev) Suzaku View : Classical Novae V2491 Cyg ( ) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2010), AN, 331, Takei et al., in prep. U Sco ( ) - Takei et al., in prep. V458 Vul ( ) - Tsujimoto et al. (2009), PASJ, 61, S69 V2672 Oph ( ) - Takei et al., in prep. Suzaku J ( ) - Takei et al. (2008), PASJ, 60, S231

52 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 52/58

53 1. MAXI Monitor of All-sky X-ray Image (MAXI) It monitors all-sky the once every 96 minutes Wide energy range (0.5 ~ 30 kev) Gas Slit Camera (GSC) Solid-state Slit Camera (SSC) 53/58

54 54/58 MAXI X-ray Image

55 2. ASTRO-H X-ray observatory (planned for launch in 2013) Future X-ray mission in Japan and US Soft X-ray Spectrometer (SXS) Soft X-ray Imager (SXI) Hard X-ray Imager (HXI) Soft Gamma-ray Detector (SGD) 55/58

56 56/58 Detectors of ASTRO-H SXS SXI HXI SGD Bandpass 0.3 ~ 10 kev 0.5 ~ 12 kev 5 ~ 80 kev 10 ~ 600 kev PSF (FPD) 1.7 arcm. 1.7 arcm. 1.7 arcm. - Energy Res. ~ 7 ev ~ 150 ev 2 kev 2 kev Time Res.????

57 Talk Plan 1. Classical Novae 1. Introduction 2. Science Strategy 2. Observations a. Observatories b. Results with the Suzaku satellite 3. Future works 4. Summary 57/58

58 58/58 Summary Five recent classical novae were observed WD mass was estimated (Suzaku J ) Plasma abundances were constrained (V458 Vul) Non-thermal X-rays were discovered (V2491 Cyg) X-ray flare was confirmed (V2672 Oph) Data is coming soon... (U Sco) My Ph.D thesis will be bright, like these Roof of SAO