Core-collapse supernovae are thermonuclear explosions

Transcription

1 Core-collapse supernovae are thermonuclear explosions Doron Kushnir Collaborators: Boaz Katz (WIS), Kfir Blum (WIS), Roni Waldman (HUJI)

2

3

4 The progenitors are massive stars SN2008bk - Red Super Giant, M=8.5±1 M sun pre-explosion Mattila et al. (2008)

5 The progenitors are massive stars SN2008bk - Red Super Giant, M=8.5±1 M sun pre-explosion explosion Mattila et al. (2008)

6 The explosion is triggered by core-collapse SN1987A: ~10 53 erg ~ 0.1 GeV/m p M sun released as neutrinos Kamiokande IMB Baksan E [MeV] t [sec]

7 The energy scale of the ejecta is thermonuclear s v = c c 104 km s 1 ) MeV m p Danziger et al. (1987)

8 Wide range of kinetic energy and 56 Ni mass Kinetic energy of the ejecta : erg Ejected 56 Ni mass: M bw 10-1 M Ni [M ] Type IIP 87A like Type IIb Type Ibc E kin [erg]

9 The main challenge - Why collapse leads to an explosion?

10 The popular ν model fails

11 The popular ν model fails if 1% of their energy is deposited in ejecta erg

12 The popular ν model fails if 1% of their energy is deposited in ejecta erg Bounce shock stalls and accretes mass, ν emission heats downstream and revives the shock.

13 The popular ν model fails if 1% of their energy is deposited in ejecta erg Bounce shock stalls and accretes mass, ν emission heats downstream and revives the shock. Problem: Fails in 1D calculations.

14 if 1% of their energy is deposited in ejecta erg Bounce shock stalls and accretes mass, ν emission heats downstream and revives the shock. Problem: Fails in 1D calculations. Maybe multi-d effects? The popular ν model fails

15 if 1% of their energy is deposited in ejecta erg Bounce shock stalls and accretes mass, ν emission heats downstream and revives the shock. Problem: Fails in 1D calculations. Maybe multi-d effects? The popular ν model fails So far, in 3D simulations the neutrinos either failed to explode the star or produce weak (<10 50 erg) explosions.

16 Hans-Thomas Janka view (arxiv ) The neutrino-driven mechanism also satisfies a number of fundamental requirements that any viable scenario should fulfill (for a detailed discussion, see Janka (2017b)). First, the mechanism is not robust, because it should allow for the formation of stellar-mass black holes (BHs), whose abundent existence has been confirmed by the recent measurements of gravitional waves from binary BH mergers (Abbott et al. (2016)). Second, it must be ine cient, because it should explain why SN explosion energies are so much lower than the gigantic amount of gravitational binding energy that is available during NS or BH formation. Third, it should be self-regulated, because the energy transferred to the ejecta does not largely exceed the binding energy of the progenitor shells outside of the degenerate core, i.e., it is as low as several erg to about erg near the lowmass side of SN progenitors and may be (1 2) erg for energetic explosions of stars around 20 M. This clearly separates such normal SNe from the significantly more powerful but much rarer hypernovae (with a rate of less than roughly one out of thousand core-collapse events), whose energies and explosion properties point to another mechanism, probably invoking the formation of BHs or magnetars and of jet-driven outflows caused by extreme amplification of magnetic fields during the collapse of rapidly rotating progenitors (see, e.g., Woosley & Bloom (2006)). The latter are the final outcome of very special and uncommon single and binary star evolution scenarios of massive stars (e.g., Levan et al. (2016)). Although first 3D simulations with energy-dependent neutrino transport have mean-

17 But the model is not abandoned

18 But the model is not abandoned simulations that neutrino-driven explosions can yield energies around 10 erg or more (e.g., Soker (2017a) and references therein). Such missing pieces in the puzzle are very likely to fall into place once longer and better resolved 3D simulations are performed,

19 Unreliable numerics But the model is not abandoned simulations that neutrino-driven explosions can yield energies around 10 erg or more (e.g., Soker (2017a) and references therein). Such missing pieces in the puzzle are very likely to fall into place once longer and better resolved 3D simulations are performed, internal ν & kinetic numerical gravitational Liebendorfer et al. (1987)

20 Thermonuclear explosion of B 2 FH

21 Thermonuclear explosion of B 2 FH The collapsing outer shells (He,C,O) are thermonuclear explosives.

22 Thermonuclear explosion of B 2 FH The collapsing outer shells (He,C,O) are thermonuclear explosives. Collapsing rotating star launches an accretion shock that cam ignite the explosive.

23 Thermonuclear explosion of B 2 FH The collapsing outer shells (He,C,O) are thermonuclear explosives. Collapsing rotating star launches an accretion shock that cam ignite the explosive citations.

24 Thermonuclear explosion of B 2 FH The collapsing outer shells (He,C,O) are thermonuclear explosives. Collapsing rotating star launches an accretion shock that cam ignite the explosive citations. Only 3 follow-up works: (Colgate & White 66, Woosley & Weaver 82, Bodenheimer & Woosley 83) conclude the scenario fails.

25 Thermonuclear explosion of B 2 FH The collapsing outer shells (He,C,O) are thermonuclear explosives. Collapsing rotating star launches an accretion shock that cam ignite the explosive citations. Only 3 follow-up works: (Colgate & White 66, Woosley & Weaver 82, Bodenheimer & Woosley 83) conclude the scenario fails. But in fact

26 Some initial condition do explode!

27 Some initial condition do explode! He-O explosive shell with

28 Some initial condition do explode! He-O explosive shell with Ø initial burning time 10 3 s

29 Some initial condition do explode! He-O explosive shell with Ø initial burning time 10 3 s Ø 5% of breakup rotation

30 Some initial condition do explode! He-O explosive shell with Ø initial burning time 10 3 s Ø 5% of breakup rotation Simple physics: Hydrodynamics + gravity + nuclear burning

31 Some initial condition do explode! He-O explosive shell with Ø initial burning time 10 3 s Ø 5% of breakup rotation Simple physics: Hydrodynamics + gravity + nuclear burning FLASH 4.0, Δx 30 km

32 Kinetic energy of the ejecta ~ erg Ejected 56 Ni mass: ~0.08 M bw 10-1 M Ni [M ] 10-2 Model 10-3 Type IIP 87A like Type IIb Type Ibc E kin [erg] Possible!

33 What sets the kinetic energy?

34 What sets the kinetic energy? E kin E dep +E bin

35 What sets the kinetic energy? Thermonuclear E kin E dep +E bin E dep MeV/m p M shell

36 What sets the kinetic energy? Thermonuclear E kin E dep +E bin E dep MeV/m p M shell E bin -GM/r M shell MeV/m p M shell

37 What sets the kinetic energy? Thermonuclear E kin E dep +E bin E dep MeV/m p M shell E bin -GM/r M shell MeV/m p M shell E kin -E bin

38 What sets the kinetic energy? Thermonuclear E kin E dep +E bin E dep MeV/m p M shell E bin -GM/r M shell MeV/m p M shell E kin -E bin Thermonuclear E kin [erg] Kushnir 2015 E kin = E bin E bin [erg]

39 What sets the kinetic energy? Thermonuclear E dep MeV/m p M shell E kin E dep +E bin ν-mechanism E dep constant E bin -GM/r M shell MeV/m p M shell E kin -E bin Thermonuclear E kin [erg] Kushnir 2015 E kin = E bin E bin [erg]

40 What sets the kinetic energy? Thermonuclear E dep MeV/m p M shell E bin -GM/r M shell MeV/m p M shell E kin -E bin E kin E dep +E bin ν-mechanism E dep constant E bin : decreases significantly with increasing mass Thermonuclear E kin [erg] Kushnir 2015 E kin = E bin E bin [erg]

41 What sets the kinetic energy? Thermonuclear E dep MeV/m p M shell E bin -GM/r M shell MeV/m p M shell E kin -E bin E kin E dep +E bin ν-mechanism E dep constant E bin : decreases significantly with increasing mass Thermonuclear ν mechanism constant E kin E dep E kin [erg] E kin [erg] complex threshold behavior no explosion E dep < E bin Kushnir 2015 E kin = E bin E bin [erg] Ugliano et al E kin = E bin E bin [erg]

42 For some CCSNe the massive star progenitors were observed SN2008bk - Red Super Giant, log 10 (L/L )=4.8±0.2 pre-explosion explosion Mattila et al. (2008)

43 More massive progenitors lead to -0.5 stronger explosions -1 log 10 (M Ni [M ]) Type IIP 87A Type IIb log 10 (L/L )

44 More massive progenitors lead to -0.5 stronger explosions -1 Stronger explosions log 10 (M Ni [M ]) Type IIP 87A Type IIb log 10 (L/L ) More massive progenitors

45 More massive progenitors lead to -0.5 stronger explosions -1 Stronger explosions log 10 (M Ni [M ]) Type IIP 87A Type IIb log 10 (L/L ) More massive progenitors In agreement with thermonuclear explosions In a possible disagreement with the ν-mechanism

46 Strong explosions leave BH remnants NSs only for weak (<10 51 erg) explosions. Strong (>10 51 erg) explosions leave BH remnants. Predicts a BH for SN1987A.

47 The ν signal from SN 1987A A luminosity drop at ~2 sec? 10 1 Luminosity per bin [10 52 erg/sec] t [sec] Blum & DK (2016)

48 Blum & DK (2016) The ν signal from SN 1987A ν-mechanism PNS accretion cooling NS

49 Blum & DK (2016) The ν signal from SN 1987A Thermonuclear ν-mechanism PNS accretion rotationinduced accretion shock PNS accretion cooling NS BH forms

50 A possible smoking gun for a thermonuclear explosion. Blum & DK (2016) The ν signal from SN 1987A Thermonuclear ν-mechanism PNS accretion rotationinduced accretion shock PNS accretion cooling NS BH forms PNS accretion for ~2 s until BH formation + rotation induced accretion shock at ~2.5 s favored by the data.

51 ν - detection implications Fraction of CCSNe with prompt BH may be as high as ~50%

52 ν - detection implications Fraction of CCSNe with prompt BH may be as high as ~50% 10 Mton detector should comfortably allow a few detections per year with Nν 5

53 ν - detection implications Fraction of CCSNe with prompt BH may be as high as ~50% 10 Mton detector should comfortably allow a few detections per year with Nν 5 Detection of BH formation will Ø solve CCSNe problem

54 ν - detection implications Fraction of CCSNe with prompt BH may be as high as ~50% 10 Mton detector should comfortably allow a few detections per year with Nν 5 Detection of BH formation will Ø solve CCSNe problem Ø Allow access to near event horizon phenomena

55 ν - detection implications Fraction of CCSNe with prompt BH may be as high as ~50% 10 Mton detector should comfortably allow a few detections per year with Nν 5 Detection of BH formation will Ø solve CCSNe problem Ø Allow access to near event horizon phenomena Unexpected discoveries (accretion induced collapse, etc.)

56 A better reaction net may allow simpler initial conditions The special required initial conditions (He-O) might have been the result of the simplified reaction network (α-net). A better reaction network may allow explosions for pure 4 He. Internal energy [MeV/mp] ρ 0 = 10 5 g/cc T 0 = 10 9 K Constant-pressure 4 He burning 21 isotopes error < 3.5% 444 isotopes α-net error 30% Time [sec]

57 Conclusions CC SNe may be thermonuclear explosions.

58 Conclusions CC SNe may be thermonuclear explosions. Demonstrated for rotating He-O shells.

59 Conclusions CC SNe may be thermonuclear explosions. Demonstrated for rotating He-O shells. Straight forward problem, solved from first principles.

60 Conclusions CC SNe may be thermonuclear explosions. Demonstrated for rotating He-O shells. Straight forward problem, solved from first principles. Preliminary agreement of kinetic energy - 56 Ni mass.

61 Conclusions CC SNe may be thermonuclear explosions. Demonstrated for rotating He-O shells. Straight forward problem, solved from first principles. Preliminary agreement of kinetic energy - 56 Ni mass. Predicts that more massive progenitors lead to stronger explosions, in agreement with observations.

62 Conclusions CC SNe may be thermonuclear explosions. Demonstrated for rotating He-O shells. Straight forward problem, solved from first principles. Preliminary agreement of kinetic energy - 56 Ni mass. Predicts that more massive progenitors lead to stronger explosions, in agreement with observations. Preliminary prediction: NS only for weak explosions, otherwise BH.

63 Resolved ignition of a detonation. Ignition scale km 500 km Infall direction

64 Resolved ignition of a detonation. Ignition scale km 500 km Infall direction

65 Resolved ignition of a detonation. Ignition scale km 500 km Runaway! Δr=500 km Δr/c s 0.1 s Infall direction

66 Resolved ignition of a detonation. Ignition scale km Ignition takes place at a subsonic region 500 km Runaway! Δr=500 km Δr/c s 0.1 s Infall direction