Detection significance [s] 3 4 5

Conservative (SD, DD) [Mpc] 70, 55 60, 48 55, 45

Optimistic (SD, DD) [Mpc] 110, 85 95, 75 85, 65

mizumura@cr.scphys.kyoto-u.ac.jp14th International Symposium on Nuclei in the COSMOS, Niigata, Japan, June 19-24, 2016

Yoshitaka Mizumura1,2, Toru Tanimori2, Atsushi Takada2, on behalf of SMILE group3

1 Unit of Synergetic Studies for Space, Kyoto University, Kyoto, Japan2 Division of Physics and Astronomy, Kyoto University, Kyoto, Japan3 http://www-cr.scphys.kyoto-u.ac.jp/research/MeV-gamma/wiki/wiki.cgi

All-sky nuclear imaging spectroscopy is a promising tool for systematic study of supernova (SN) explosions. Especially, progenitor scenarios of type Ia SNe are not well-understood yet. Here, we report an nuclear imaging telescope, Electron-Tracking Compton Camera (ETCC), and its expected performance with satellite-based all-sky imaging, which enable us to observe nuclear lines from SN Ia at a distance beyond 40 Mpc (~several SNe/years).

100 days(@40-140 d), 0.7-4.0 MeV

20 40 60 Mpc

Distance distri.

in 5 yrs

56N

i ge

nIn

clin

atio

n an

gle

20 40 60

±20%

±30%

20 40 60

20 Mpc 40 Mpc 40 Mpc20 Mpc

100keV

4MeV

2MeV

200keV

500keV

812

1561keV

480270

158

56Ni

56Co 847

1038

1238 1771

2038

2598

3253keV

750

0.7 MeV

1MeV

SD

DD

56Ni (t1/2 = 6.1 d) → 56Co (77.2 d) → 56Fe

SD

DDIR-Opt.-UV

Uncertainty from inclination

angle of the orbit

SD DD

50 keV—4 MeV

Obvious diff.b/w SD and DD

©David A. Hardy/AstroArt

Mass accretion from companion star (SD)

©NASA

Violent merger of white dwarfs (DD)Which

scenario is?

1. Progenitor scenarios of Ia SNe

A. Summa, et al., A&A 554, A67 (2013)

800

Nuclear gamma-ray is a powerful tool to distinguish SD and DD.

R. Diehl, et al., Science 345, 1162 (2014)E. Churazov, et al., Nature 406, 512 (2014)

SN2014J: SN Ia@3.5Mpc (Very rare: ~1/40 SN/yr)

SPIIBIS

847keV 1238

keV1038keV

INTEGRAL successfully observed 56Ni and 56Co lines,but it is difficult to resolve

the puzzle of SD vs. DD

True nuclear imaging spectroscopy and systematic

study are required!!

MeV g

MeV g

COMPTEL type ETCC type

COMPTEL type ETCC obs.

improvement

Instruments on satellite:4 x (50 cm)3 ETCC

Effective Area:240 cm2@1 MeV

PSF: 2o @1 MeV

ΔE/E: 5%@662 keV

Field of View: 2p srEffective Exposure: 33%Assumed B.G. flux:2 times of reported flux

e- Energy: Keg Energy: Eg

Eg

Ke

KeEg

cme

=

2

1cos

Details in [23-PS2.78]T. Tanimori, et al., ApJ 810, 28 (2015)

3. Detectable nuclear gamma-ray lines

Please check also SMILE balloon experiment series.Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment

Expected performance

SN Ia rate(<60 Mpc): ~2x10-5 [yr-1 Mpc-3] Dist.[Mpc]

SN rate[yr-1]

5 yrs[SNe]

15 0.28 1.420 0.67 3.440 5.4 2760 18 90

D. Maoz, and F. Mannucci,Publ. Astron. Soc. Australia 29, 447 (2013)

56Ni gen.

Incl

inat

ion

angl

e

±20%

±3

0%

Flux uncertainty:56Ni gen. 20% (SD & DD)

Inclination 30% (only DD)

4. Averaged lightcurve of type Ia SNe

SD

3.5 Mpc

20-40 Mpc (23 SNe) 40-60 Mpc (63 SNe)10

days

20-60 Mpc (86 SNe)

SD

DD

Generated #(SD, DD)

SD ratio[%]

Best fittedSD ratio[%]

0, 86 0.0 4 ± 1120, 66 23.3 23 ± 342, 44 48.8 44 ± 364, 22 74.4 76 ± 386, 0 100 90 ± 3

Can we measure co-existence ratio of SD and DD?

A puzzle of SN Ia, SD vs. DD,

can be resolved

5. Detection limits & prospects

Obs. in 50-100 d

BG subtracted BG subtracted BG subtracted BG subtracted

DD

3.5 Mpc

56Co lines will be observed from ~several SNe/years

T. Tanimori, et al., ApJ 810, 28 (2015)

Distance[Mpc]

#[SNe]

Averageddist.[Mpc]

0-20 4 14.020-40 23 31.940-60 63 51.30-60 90 44.7

Emulation of type Ia SNe

SDDD

SDDD

Random numbers

Expectation of averaged lightcurves

orCo-existence

!?

Yes!! we can measure the ratio w/ 20-30% err.

If we achieve observations of Ia SNeup to 100 Mpc, >400 SNe/5yrs are expected.

Nuclear imaging spectroscopy with ETCC enables us to try systematic observational studies of type Ia SNe, andit will open a new era of nuclear physics in the cosmos.

SD

DD

Conservative model: 2xBG, All-sky surveyOptimistic model: 1xBG, Pointing mode

days

2. Nuclear imaging spectroscopy w/ ETCC

Mpc

1 mCrab sensitivity