gamma$rays(from(sn2014j - max planck · pdf fileand!!(1.91!±0.67) !104!phcm 2 s 1 (812...

Gamma-‐Rays from SN2014J

Measuring the 56Ni decay chain

Roland Diehl (MPE Garching, Germany) with Mar:n Krause, Thomas Siegert, Jochen Greiner, Xiaoling Zhang (MPE) Wolfgang Hillebrandt, Markus Kromer, Stuart Sim, Stefan Taubenberger…

»  Clayton, Colgate, & Fishman 1969

Nuclear Astrophysics at Ringberg 2016

Gamma-‐Ray Lines from SNIa

Roland Diehl 2

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:

Nuclear Astrophysics at Ringberg 2016 Roland Diehl 3

ESA mission Launch 2002

Expected rate: >1/5years

The first best opportunity (l+9y): SN2011fe •  4 Ms of observing :me

•  Upper limit (Isern+ 2013) à –  From ‘early’ observaCons only, model spectra fiGng –  “SPI detecCons unlikely even for close SN

unless lines are “narrow”” –  IBIS appears the more sensiCve instrument for broad lines


“late” (unpublished)

“early” (Isern+2013)

SN2014J •  In M82

(Starburst Galaxy) •  Discovered 22 Jan 2014 Cao et al. ATel # 5786

•  Likely Explosion Date: 14 Jan 2014 (14.75 +/-‐0.3d)

•  Distance 3.3….3.53 Mpc, l=141.41o, b=40.56o


SN2014J: a Unique Opportunity for INTEGRAL

Observa:ons: 31 Jan – 26 Jun (w gaps, but 7.1 Ms total), days 17-‐139 aner explosion

•  Exclude Early (He-‐cap) Models?

•  Detect 56Co γ-‐rays and Discriminate Among Models?

SPI Narrow line 1 Ms

SPI dE~25 keV, 3 Ms


56Ni Radioac:vity Decay Chain and Gamma-‐Rays

• 

56Ni

56Fe

e--capture (98%)

γ 750 keV (50%)

τ =8.8 d

56Co

γ 847 keV (100%)

τ = 111.3 d

γ 812 keV (86%)

0+

1+

2+

4+

2+

0+

4+

γ 1238 keV (68%)

e- - capture (81%) γ 158 keV (100%)

3+

0+ γ 270+480 keV (36%)

3,4+ β+ - decay (19%,E~0.6MeV)

γ’s 3.253(8%),2.598(17%), 1.038(14%), 1.4,1.771(16%) MeV

γ-‐rays: ~50…100 days


SN2014J data Jan – Jun 2014: 56Co lines – Detec:on of 847 and 1238 keV lines from 56Co decay at days 50-‐100

–  Confirm SN Ia model

– M56Ni es:mated from 56Co line flux with escape.= 0.6 à 0.61±0.13 M¤

–  Significantly Doppler-‐broadened

•  Churazov et al., Nat, 2014


Churazov et al. 2014

The Challenge of Finding SN2014J Gamma-‐Rays –  Current Gamma-‐Ray Telescopes Have Large Intrinsic Background

•  Cosmic Ray Ac:va:on of Spacecran and Instrument

expected signal from SN2014J

typical background intensity

from Churazov et al., 2014 Nuclear Astrophysics at Ringberg 2016 Roland Diehl 9

INTEGRAL Cosmic Photon Measurements: The SPI Ge γ-‐Spectrometer

Coded-‐Mask Telescope Energy Range 15-‐8000 keV Energy Resolu:on ~2.2 keV @ 662 keV Spa:al Precision 2.6o / ~2 arcmin Field-‐of-‐View 16x16o

Coded Mask Telescope: Cas:ng a Shadow


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 (ßphysics!) •  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

T Siegert, master thesis TUM (2013)


26Al 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 2016

Roland Diehl 13

SN2014J: Early 56Ni •  Gamma-‐ray spectra from the SN posi:on à

–  Clear detec:ons of the two strongest lines expected from 56Ni with the INTEGRAL Spectrometer ‘SPI’

158 keV 812 keV


•  INTEGRAL Obs from 31 Jan :ll 26 Jun 2014

Longterm Data: Broad Lines from 56Co!

847 keV

MPE INTEGRAL Team


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 56Ni à SPI-‐only result, publish as well

Discussion w E. Churazov 20 Mar: “no comment”

Discussions at NuclAstro2014/Ringberg (Isern, Diehl, Hillebrandt, Siegert,…)

INTEGRAL/SPI Analysis for early 56Ni gamma-‐rays

•  56Ni-‐decay gamma-‐rays from SN2014J! •  Excess signal in 158 and 812 keV lines, ~3σ

158 keV

812 keV

SPI/INTEGRAL 158 & 812 keV


SN2014J: Early 56Ni •  Imaging in line bands, and in adjacent bands:

–  Line emission from SN2014J more plausible than noise / chance coincidence

158 keV

812 keV

161-‐171 keV

814-‐824 keV


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 fi�ng approach, results may differ

F Narrow line, ~unshined


Early 56Ni Gamma-‐Rays: τ=8.8d • 


SN2014J: Early 56Ni •  Gamma-‐ray spectra from the SN posi:on à

–  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)

–  56Ni mass es:mate (backscaled to explosion): ~0.06 M¤

158 keV 812 keV


SN2014J: An unusual explosion? • 

con:nuum near 812 keV

Simulating how an exploding belt of accreted He would be observed in gamma-rays: Polar viewing à unshifted lines Equatorial viewing à blue shift

W7 model

He belt model

polar view equatorial view

A belt of He accreted from the companion star à He explosion, triggering the SNIa explosion of the CO white dwarf (M<Mch)

Markus Kromer


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"


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??




158 keV


F Narrow line, ~unshined ? or ? F Broad & redshined line




158 keV


F Narrow line, ~unshined, is most likely (from data analysis alone; no model)

F Underlying broad line cannot be excluded


SN2014J: An unusual explosion? •  SN2014J had significant 56Ni 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<Mch)


Possible geometries of outer 56Ni:

Diehl+, Science (2014) Isern+, arxiv (2016) Roland Diehl 28

•  INTEGRAL Obs from 31 Jan :ll 26 Jun 2014

Longterm Data: Broad Lines from 56Co!

847 keV

MPE INTEGRAL Team


SN2014J data Jan – Jun 2014: 56Co lines –  The 847 keV line from 56Co decay – Different spectral binning

à Structured spectrum – all from the broadened 847 keV line? •  Diehl et al. 2015


SN2014J data Jan – Jun 2014: 56Co lines The 56Co decay lines Different spectral binning Different epochs

à –  Structured and evolving spectrum à all from broadened 56Co decay lines?

– Non-‐radial mo:ons, or sightlines w varying depths??

•  Diehl et al., A&A (2015)


SN2014J data Jan – Jun 2014: 56Co lines –  Brightness evolu:on of the 56Co decay lines à

–  Consistent brightness evolu:on of both lines

•  Ra:o ~0.62 +/-‐0.28 (0.68) –  Plausible kinema:cs

–  ~Consistent with many plausible models

–  Choice of spectral “line emission” assignments may affect details

“847 keV”

“1238 keV”


Determining the 56Ni mass – Fi�ng :me histories of line emission from models to data

–  1D models for SN2014J (The & Burrows’14) –  Three alterna:ves to determine a “56Co line flux”

•  0.49 ± 0.09 M¤ of 56Ni (averaging among three best models)


SN2014J data Jan – Jun 2014: 847 keV 56Co line

à Irregular brightness evolu:on

à Compare high/low res data to models

56Ni mass (fi�ed) = 0.49 ±0.09 M¤ �

(cmp from bol. Light à 0.42 ±0.05 M¤ Diehl et al. A&A 2015


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?

Line Search •  Random Search: Try to Fit a Line (Centroid,Intensity, Width)

158 keV 812 keV


Line Shape Analysis •  Velocity Constraints from 56Ni 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) +2000 (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 ∞ 32500 (95.4) <8250 (4.4) <2400 (6.5)


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+ 2015


gamma$rays(from(sn2014j - max planck · pdf fileand!!(1.91!±0.67) !104!phcm 2 s 1 (812...

Documents