Gamma- Rays from SN2014J

Transcription

1 Gamma- Rays from SN2014J Roland Diehl (MPE Garching, Germany) with Mar:n Krause, Thomas Siegert, Jochen Greiner, Xiaoling Zhang (MPE) Wolfgang Hillebrandt, Markus Kromer, Stuart Sim, Stefan Taubenberger Measuring the 56 Ni decay chain

2 Gamma- Ray Lines from SNIa» Clayton, Colgate, & Fishman

3 ESA mission Launch 2002 SN Ia γ- ray observa:ons: a science goal for INTEGRAL since its design A ToO Proposal has been in place every year: Jordi Isern et al.: If 1 Mpc < d < 8 Mpc and mb>9.5: 1+1 Ms à observa:ons proposed: Expected rate: >1/5years Roland Diehl Nuclear Astrophysics at Ringberg

4 The first best opportunity (l+9y): SN2011fe 4 Ms of observing :me late (unpublished) early (Isern+2013) Upper limit (Isern+ 2013) From early observacons only, model spectra figng à SPI deteccons unlikely even for close SN unless lines are narrow IBIS appears the more sensicve instrument for broad lines 4

5 SN2014J In M82 (Starburst Galaxy) Discovered 22 Jan 2014 Cao et al. ATel # 5786 Likely Explosion Date: 14 Jan 2014 ( /- 0.3d) Distance Mpc, l= o, b=40.56 o 5

6 SN2014J: a Unique Opportunity for INTEGRAL Observa:ons: 31 Jan 26 Jun (w gaps, but 7.1 Ms total), days aner explosion Exclude Early (He- cap) Models? Detect 56 Co γ- rays and Discriminate Among Models? SPI Narrow line 1 Ms SPI de~25 kev, 3 Ms 6

7 56 Ni Radioac:vity Decay Chain and Gamma- Rays 0+ τ =8.8 d 56 Ni e - -capture (98%) γ 750 kev (50%) γ kev (36%) γ 812 kev (86%) γ 158 kev (100%) e - - capture (81%) τ = d 3,4+ 56 β Co + - decay γ s 3.253(8%),2.598(17%), (19%,E~0.6MeV) 1.038(14%), 1.4,1.771(16%) MeV 4+ γ- rays: ~ days γ 1238 kev (68%) γ 847 kev (100%) 56 Fe 7

8 SN2014J data Jan Jun 2014: 56 Co lines Detec:on of 847 and 1238 kev lines from 56 Co decay at days Confirm SN Ia model M 56Ni es:mated from 56 Co line flux with escape.= 0.6 à 0.61±0.13 M Significantly Doppler- broadened Churazov et al., Nat, 2014 Churazov et al

9 The Challenge of Finding SN2014J Gamma- Rays Current Gamma- Ray Telescopes Have Large Intrinsic Background Cosmic Ray Ac:va:on of Spacecran and Instrument typical background intensity expected signal from SN2014J from Churazov et al.,

10 INTEGRAL Cosmic Photon Measurements: The SPI Ge γ- Spectrometer Coded Mask Telescope: Cas:ng a Shadow Roland Diehl Coded- Mask Telescope Energy Range kev Energy Resolu:on ~ kev Spa:al Precision 2.6o / ~2 arcmin Field- of- View 16x16o Nuclear Astrophysics at Ringberg

11 SPI data analysis for line spectroscopy Background modeling from detailed mission data spectroscopy à exploit physics of lines à consistent high- resolu:on model Integrate data over 3 days Fit spectra in detail (con:nuum, lines, steps ) Fix spectral- shape and detector ra:o parameters T Siegert, master thesis TUM (2013) (ß physics!) Normalize the spectral- feature template per poin:ng, and apply individual- detector responses (degradacon & annealing!) One 3- day orbit, one detector One 1/2h poin:ng, one detector 11

12 SPI data analysis for line spectroscopy Background modeling from detailed mission data spectroscopy à exploit physics of lines à consistent high- resolu:on model Integrate data over 3 days Fit spectra in detail (con:nuum, lines, steps ) Fix spectral- shape and detector ra:o parameters T Siegert, master thesis TUM (2013) (ß physics!) Normalize the spectral- feature template per poin:ng, and apply individual- detector responses (degradacon & annealing!) One 3- day orbit, one detector One 1/2h poin:ng, one detector 12

13 26 Al line studies Sky and background are clearly separated» using Single Events (No contamina:on; The SPI response is only well established for SE, not PE) preliminary, MPE Jan

14 SN2014J: Early 56 Ni Gamma- ray spectra from the SN posi:on à 158 kev 812 kev Clear detec:ons of the two strongest lines expected from 56 Ni with the INTEGRAL Spectrometer SPI 14

15 Longterm Data: Broad Lines from 56 Co! INTEGRAL Obs from 31 Jan :ll 26 Jun 2014 MPE INTEGRAL Team 847 kev 15

16 Towards publishing INTEGRAL results SN event and ToO discussion late Jan 2014 Agreement: SNIa ToO proposal PI Isern = study coordinator Feb Apr: Discussions & shared quicklook towards Co lines Isern in a difficult posi:on as a theorist; analysis in Garching,Toulouse, Paris RD report on early Ni lines broadly circulated 10 March à no comments! Atel Churazov et al. released 25 Mar: "SN2014J Co line detec:on Team- internal report SPI narrow lines from 56 Ni à SPI- only result, publish as well Discussion w E. Churazov 20 Mar: no comment Discussions at NuclAstro2014/Ringberg (Isern, Diehl, Hillebrandt, Siegert, ) 16

17 INTEGRAL/SPI Analysis for early 56 Ni gamma- rays 56 Ni- decay gamma- rays from SN2014J! Excess signal in 158 and 812 kev lines, ~3σ 158 kev SPI/INTEGRAL 158 & 812 kev 812 kev 17

18 SN2014J: Early 56 Ni Imaging in line bands, and in adjacent bands: 158 kev kev 812 kev kev Line emission from SN2014J more plausible than noise / chance coincidence 18

19 Line Uncertain:es: Search and method biases Random Search: Try to Fit a Line (Centroid,Intensity, Width) 158 kev Depending on resolu:on of the analysis method, and on fing approach, results may differ F Narrow line, ~unshined 19

20 Early 56 Ni Gamma- Rays: τ=8.8d 20

21 SN2014J: Early 56 Ni Gamma- ray spectra from the SN posi:on à 158 kev 812 kev Intensi:es: (1.14 ±0.43) 10-4 ph cm - 2 s - 1 (158 kev line) and (1.91 ±0.67) 10-4 ph cm - 2 s - 1 (812 kev line) 56 Ni mass es:mate (backscaled to explosion): ~0.06 M 21

22 SN2014J: An unusual explosion? A belt of He accreted from the companion star à He explosion, triggering the SNIa explosion of the CO white dwarf (M<M ch ) Simulating how an exploding belt of accreted He would be observed in gamma-rays: Polar viewing à unshifted lines Equatorial viewing à blue shift polar view equatorial view Markus Kromer He belt model con:nuum near 812 kev W7 model 22

23 First INTEGRAL Papers on SN2014J SN event and ToO discussion late Jan 2014 Agreement: SNIa ToO proposal PI Isern = study coordinator Feb Apr: Discussions & shared quicklook towards Co lines Isern in a difficult posi:on as a theorist; analysis in Garching,Toulouse, Paris RD report on early Ni lines broadly circulated 10 March à no comments! Atel Churazov et al. released 25 Mar: "SN2014J Co line detec:on" 2 Papers accepted in 'Science' and 'Nature'; ESA PR "coordinated" 23

24 Another analysis of SN2014J SPI data Isern et al, dran/arxiv 2016 Broad- bin analysis, convolving SN Ia model spectra (i.e. model dependent) à find a broad line Hi- res analysis shows sub- structure 158 kev line plus red/blue- shined 158 kev?? 24

25 Another analysis of SN2014J SPI data Isern et al, dran/arxiv 2016 Broad- bin analysis, convolving SN Ia model spectra (i.e. model dependent) à find a broad line Hi- res analysis shows sub- structure 158 kev line plus red/blue- shined 158 kev?? 25

26 Line Uncertain:es: Search and method biases Random Search: Try to Fit a Line (Centroid,Intensity, Width) 158 kev Depending on resolu:on of the analysis method, and on fing approach, results may differ F Narrow line, ~unshined? or? F Broad & redshined line 26

27 Line Uncertain:es: Search and method biases Random Search: Try to Fit a Line (Centroid,Intensity, Width) 158 kev Depending on resolu:on of the analysis method, and on fing approach, results may differ F Narrow line, ~unshined, is most likely (from data analysis alone; no model) F Underlying broad line cannot be excluded 27

28 SN2014J: An unusual explosion? SN2014J had significant 56 Ni near the surface A belt of He accreted from the companion star à He explosion, triggering the SNIa explosion of the CO white dwarf (M<M ch ) Possible geometries of outer 56 Ni: Isern+, arxiv (2016) Diehl+, Science (2014) 28

29 Longterm Data: Broad Lines from 56 Co! INTEGRAL Obs from 31 Jan :ll 26 Jun 2014 MPE INTEGRAL Team 847 kev 29

30 SN2014J data Jan Jun 2014: 56 Co lines The 847 kev line from 56 Co decay Different spectral binning à Structured spectrum all from the broadened 847 kev line? Diehl et al

31 SN2014J data Jan Jun 2014: 56 Co lines The 56 Co decay lines Different spectral binning Different epochs à Structured and evolving spectrum à all from broadened 56 Co decay lines? Non- radial mo:ons, or sightlines w varying depths?? Diehl et al., A&A (2015) 31

32 SN2014J data Jan Jun 2014: 56 Co lines Brightness evolu:on of the 56 Co decay lines à 847 kev Consistent brightness evolu:on of both lines Ra:o ~0.62 +/ (0.68) Plausible kinema:cs 1238 kev ~Consistent with many plausible models Choice of spectral line emission assignments may affect details 32

33 Determining the 56 Ni mass Fing :me histories of line emission from models to data 1D models for SN2014J (The & Burrows 14) Three alterna:ves to determine a 56 Co line flux 0.49 ± 0.09 M of 56 Ni (averaging among three best models) 33

34 SN2014J data Jan Jun 2014: 847 kev 56 Co line à Irregular brightness evolu:on à Compare high/low res data to models 56 Ni mass (fiƒed) = 0.49 ±0.09 M (cmp from bol. Light à 0.42 ±0.05 M Diehl et al. A&A

35 Gamma- Rays from a Supernova Ia: SN2014J First direct detec:on of 56Ni decay in a SNIa Structured 56Co gamma- ray emission à clumpy SN?

36 Line Search Random Search: Try to Fit a Line (Centroid,Intensity, Width) 158 kev 812 kev 62

37 Line Shape Analysis Velocity Constraints from 56 Ni lines Lines are not significantly Doppler- Shined Lines are not or only modestly broadened Underlying broader (>30 kev) line components possible Significance FWHM (158 kev line) [km/s (kev)] FWHM (812 kev line) [km/s (kev)] Bulk Shift (158 kev line) [km/s (kev)] Bulk Shift (812 kev line) [km/s (kev)] Best Fit 0 (1.77) 0 (2.33) (1.05) 0 1 σ 2400 (2.1) 600 (2.8) <2100 (1.1) 0 2 σ 6100 (3.7) 1400 (4.4) <2150 (1.1) <100 (0.3) 3 σ (95.4) <8250 (4.4) <2400 (6.5) 63

38 NIR spectra: Co ionisa:on states Co II and Co III Co III line does not fade as quicky as models predict» SOFIA observa:ons; Vacca