Elba XIV, June 27th – July 1st, 2016
Supernova neutrino: predic on and detec on
Shunsaku Horiuchi (Center for Neutrino Physics, Virginia Tech)
Image credit: NASA/ESA Neutrinos as cosmic messengers
Only neutrinos, with their extremely small interac on cross sec ons, can enable us to see into the interior of a star... John N. Bahcall, Phys. Rev. Le . 12, 303 (1964)
• allow us to see op cally thick (to photons) regions Neutrinos: • experience li le a enua on through cosmic space • probes unrivaled extreme environments • direct hadronic indicator Neutrino detec on is difficult; has been addressed by detectors, e.g., IceCube, Super- Kamiokande, and many others
Neutrinos
photons Source
Cosmic rays Cosmic rays Elba XIV Horiuchi (Virginia Tech) Magne c field 2 Massive stars core collapse
Massive (>8Msun) star structure Core collapse (implosion)
H He C O Si Fe
~8000 km
Elba XIV Horiuchi (Virginia Tech) Adapted from slides by G. Raffelt 3 Core-collapse supernovae
Newborn neutron star Explosion Core collapse (implosion) Explosion
Neutrino Cooling
Energy budget ~ 3 x 1053 erg R: 8000 km à ~20 km 99% into neutrinos ρ: ~109 g cm-3 à ~1014 g cm-3 (0.01% into photons) T: ~1010 K à ~30 MeV
Elba XIV Horiuchi (Virginia Tech) Adapted from slides by G. Raffelt 4 SN1987A as an example Observa on: massive star progenitor, Observa on: MeV neutrino burst Type II supernova, nuclear decay lines, etc las ng ~10s
A few hours
Great insights! Ø Importance of weak interac ons Ø Total binding energy Theory: core collapse emits Ø Direct evidence of Ni neutrinos and launches synthesis supernova shock, causes Ø Limits on axions and explosive nucleosynthesis similar new par cles Ø Elba XIV Horiuchi (Virginia Tech) Many others 5 The explosion mechanism
Stalled shock: The shock stalls, pressure è inside balanced by ram pressure outside: Cri cal curve 2 Cri cal curve p = ⇢ v Explosions The neutrino mechanism: deposit a frac on of the energy in neutrinos via capture on free neutrons & protons Bethe & Wilson (1985), Colgate et al (1966), …
VS ! Neutrino luminosity Explosion failure and black hole forma on
Mass accre on rate
To be tested with simula on & observa ons!
Elba XIV Horiuchi (Virginia Tech) 6 Importance of asphericity
Failure in spherical symmetry: long problem since the 1980, confirmed in 2000s e.g., Liebendoerfer et al (2001, 2004) SASI:
Entropy @200ms 2D 2D 3D 3D Mixing! Convec on:
1D 1D
Takiwaki et al (2014) Lentz et al (2015) 1000 km
Elba XIV Horiuchi (Virginia Tech) 7 Systema c core-collapse simula ons Sophis cated simula ons [no systema c studies yet] • 3D with neutrino transport • Few progenitor models • Address: explosibility, neutrino and gravita onal wave signals Hanke et al (2013, 2014), Melson et al (2015), Lentz et al (2015), Takiwaki et al (2016) … First systema c studies in spherically symmetry • Spherically symmetric with parameterized neutrino hea ng • ~700 progenitor models • GR gravity • Address: progenitor dependence, black hole forma on Ugliano et al (2012), O’Connor & O (2011, 2013), Ertl et al (2015)
Recent systema c study in axis-symmetry • Axis-symmetric with simplified neutrino transport (IDSA) • ~400 progenitor models • Newtonian gravity
• Address: progenitor dependence, SASI, other observables (MNi, etc) Nakamura et al (2014) Elba XIV Horiuchi (Virginia Tech) 8 Explodability and compactness
Compactness: is a useful indicator to discuss the eventual outcome of core collapse
Black hole forma on occurs more readily for Successful / failed explosion threshold occurs larger compactness. approximately ξ2.5 ~ 0.45
explosions
O’Connor & O (2011), Ugliano et al (2012); see also BH forma on for ξ2.5 > 0.35 Pejcha & Thompson (2015), Ertl et al (2015) Other are close: Elba XIV Horiuchi (Virginia Tech) (and explosions for ξ2.5 < 0.15) 9 Results in 2D
Two-dimensional systema c study • 2D with IDSA spectral transport • Newtonian • LS(K=220) EOS • 378 progenitor models (101 solar, 247 Z = 10-4, 30 zero metal)
Elba XIV Horiuchi (Virginia Tech) 10 Results in 2D
2. Higher Mdot à later revival 5. More neutrino à energe c explosion
1. Higher compactness à higher Mdot 3. Later revival à more massive NS
4. More massive NS à more neutrinos 6. Energe c explosion à More Nickel
Nakamura et al 2014 Elba XIV Horiuchi (Virginia Tech) 11 Cri cal compactness in 2D
Limita on: • 2D setup is conducive to Failed explosions e.g., Hanke et al (2012) BH • Remnants above 2.4 Msun baryonic mass not realis c and may not explode in reality.
à Cri cal ξ2.5 < ~0.4 – 0.5
Cri cal compactness ξ2.5 In 1D: 0.35 – 0.45 In 2D: < 0.4 – 0.5
Horiuchi et al (2014)
Elba XIV Horiuchi (Virginia Tech) 12 Neutrino emission in black hole forma on
Neutrino emission: Black hole necessarily goes through rapid mass accre on à ν emission is Black hole case more luminous and ho er (EOS (40Msun) dependent) NS case (13Msun) Sumiyoshi et al 2006, 2007, 2008, 2009 Fischer et al 2009 Nakazato et al 2008, 2010, 2012 Sekiguchi & Shibata 2011 O’Connor & O 2011 Plus various others
Neutrino termina on: Neutrino detectors can directly detect the moment of black hole forma on (if it occurs during the first O(10) seconds) Beacom et al (2001) Liebendoerfer et al (2004)
Elba XIV Horiuchi (Virginia Tech) 13 What is the failed collapse rate? O’Connor & O (2011)
Expected to be low (<7%) among solar metallicity stars.
But it may be higher: many recent hints suggest the rate could be higher O’Connor & O (2011)
Red supergiant problem Black hole mass func on Supernova rate Survey about nothing
10 ] -3 Birthrate of massive stars Mpc -1 yr -4 Rate of bright collapse 1
Li et al. (2010b) Cappellaro et al. (1999) Botticella et al. (2008) rate density [10 Cappellaro et al. (2005) Bazin et al. (2009) Dahlen et al. (2004) 0.1 0 0.2 0.4 0.6 0.8 1.0 Redshift z ~20-30% ~20-30% ~10-30% ~10-40% Smar et al (2009) Kochanek et al (2014) Horiuchi et al (2010) Gerke et al (2014) Elba XIV Horiuchi (Virginia Tech) 14 1. Red supergiant problem
Some stars don’t explode? Observa onally, the red supergiants with This is ~20% of massive stars.
mass 16 – 25 Msun are not exploding The mass range in ques on is an island of high compactness à theore cally more
likely to form black holes.
Assuming all explode
With Mcut 16.5 Msun
Horiuchi et al (2014); see also Kochanek (2014)
Requires low cri cal ξ2.5 ~ 0.2 Smar (2015) à Needs tes ng by 3D simula ons Elba XIV Horiuchi (Virginia Tech) 15 2. Black hole mass func on
Compact object mass func on:
There are hints of a dearth of compact black A cri cal compactness ξ2.5~0.2 predicts a holes just above the NS mass range black hole mass func on with a cutoff
e.g., Kreidberg et al. (2012), Kizeltan et al. (2013) Lovegrove & Woosley 2013, Kochanek (2014) Elba XIV Horiuchi (Virginia Tech) 16 3. Cosmic core-collapse rate Birth rate of massive stars From many observa ons
10 (hundreds) ] -3 Birthrate of massive stars Observed supernova rate Derived from observa ons Mpc
-1 of luminous supernovae
yr (many recent updates) -4 Rate of bright collapse (Core-collapse rate) – 1 (supernova rate) = DIM or DARK collapse rate Li et al. (2010b) Cappellaro et al. (1999) Approximately 30 – 50 % Botticella et al. (2008) • Some of this can be due to rate density [10 Cappellaro et al. (2005) Bazin et al. (2009) collapse to black holes. Dahlen et al. (2004) • Other possibili es include 0.1 0 0.2 0.4 0.6 0.8 1.0 ONeMg collapse, dust Redshift z (especially from mass loss), Horiuchi et al (2011) fall back intense collapse,
Elba XIV Horiuchi (Virginia Tech) etc 17 Correc on due to dim supernovae
Dust ex nc on distribu on Large uncertainty from dust a enua on à be er model raises CCSN rate 30-50%
Observed
model Two more (2002hh & 2009hd) at 3.7 & 4.1 Number of supernovae
Less ß Dust ex nc on à more Ma la et al (2012)
à Failed collapse frac on reduced to 10-30% Dahlen et al, ApJ (2012) Elba XIV Horiuchi (Virginia Tech) 18 4. Searching for failed explosions: Survey about nothing
Survey About Nothing • Look for the disappearance of red- supergiants in nearby galaxies • Monitor 27 galaxies with the Large Binocular Telescope à ~106 red supergiants with luminosity > 104 Lsun à expect ~1 core collapse /yr à In 10 years, sensi ve to 20 – 30% failed frac on at 90%CL
Kochanek et al. (2008)
Gerke et al. (2015) Elba XIV Horiuchi (Virginia Tech) 19 SN2011dh deficit
V-band
R-band
Results so far: In 4 years running, • 3 luminous CC supernovae: SN2009dh, SN2011dh, SN2012 With the candidate • 1 Type Ia (SN2011fe) • 1 candidate failed supernova: NGC6946-BH1 (@~6Mpc)
à Peak failed collapse rate 10 – 40% Note: the candidate’s mass es mate is 18–25 Msun (!) Gerke et al. (2015)
Elba XIV Horiuchi (Virginia Tech) 20 NEUTRINO PROBES
Elba XIV Horiuchi (Virginia Tech) 21 Modern neutrino detectors
MiniBooNE (800 ton LqSc) Nova (15 kton LqSc) [RENO (~18 kton LqSc)] Super-Kamiokande (32 kton H2O) SNO+ (800 ton LqSc) EGADS (200 ton H2O + Gd) HALO (76 ton Pb) KamLAND (1 kton LqSc) ~ [DUNE (~34 kton LAr)] [Hyper-Kamiokande ( 0.6 Mton H2O)]
LVD (1 kton LqSc) Daya Bay (300 ton LqSc) Borexino (300 ton LqSc) [JUNO (~20 kton LqSc) ] [km3Net (Gton water)] IceCube (Gton Ice) [LENA (50 kton LqSc)]
Elba XIV Horiuchi (Virginia Tech) 22 Neutrino detec on: Cherenkov
Super-Kamiokande IceCube E > 10 GeV Eν > few MeV ν
ν
e lepton • Each OM has intrinsic noise of ~300 Hz • Supernova at 10 kpc yields ~200 (L/1052 erg/s) Hz hits per OM • Supernova appears as correlated noise in 5000 OMs e.g., Halzen et al (1995)
Elba XIV Horiuchi (Virginia Tech) 23 Distance scales and physics outcomes
Nν >> 1 : BURST Nν ~ 1 : MINI-BURST Nν << 1 : DIFFUSE
SN rate ~ 0.01 /yr SN rate ~ 0.5 /yr SN rate ~ 108 /yr
~kpc ~Mpc ~Gpc Adapted from Beacom (2012) Galac c burst Mini-bursts Diffuse signal Physics Explosion supernova variety Average emission, mul -popula ons reach mechanism, with individual ID astronomy Required Basics are Next genera on Upcoming upgrades detector covered
Elba XIV Horiuchi (Virginia Tech) 24 Supernova neutrino detec on
High number sta s cs expected from a Galac c core collapse (at 10 kpc distance)
Mirizzi et al (2015) Elba XIV Horiuchi (Virginia Tech) 25 Observing the SASI mechanism
SASI signatures: SASI’s me varia ons (~10-20 ms) in the neutrino luminosity and energy can be measured, if we have excellent sta s cs.
Tamborra et al (2013), see also Lund et al (2010, 2012), based on Hanke et al (2013)
Elba XIV Horiuchi (Virginia Tech) 26 Measuring the compactness
Events light curve at SK: The ra o of events: See a clear dependence on the ξ, which is useful in light of systema c uncertain es. drives the accre on history Many choices of me bins for specific ξ 12 8 D
10
0-50ms 6 @SK
bins @SK /N 8 4 ms
1 2 ê 6 200-250ms
N 0 4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 events @ 2 8 n
N @HK
0-50ms 6 0 0.0 0.2 0.4 0.6 0.8 1.0 /N t s 4 2 200-250ms
N 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Compactness ξ1.75 ξ2.5 0.005 0.42 @ D
Elba XIV Horiuchi (Virginia Tech) 27 Distance scales and physics outcomes
Nν >> 1 : BURST Nν ~ 1 : MINI-BURST Nν << 1 : DIFFUSE
SN rate ~ 0.01 /yr SN rate ~ 0.5 /yr SN rate ~ 108 /yr
~kpc ~Mpc ~Gpc Adapted from Beacom (2012) Galac c burst Mini-bursts Diffuse signal Physics Explosion supernova variety Average emission, mul -popula ons reach mechanism, with individual ID astronomy Required Basics are Next genera on Upcoming upgrades detector covered
Elba XIV Horiuchi (Virginia Tech) 28 Diffuse Supernova Neutrino Background
Observed positron Input 1: supernova neutrino spectrum (intensely studied, spectrum quan ty of interest)
dN cdt dN e (E )=N (E ) R (z) (1 + z) ⌫ [E (1 + z)] dz dE e p ⌫ CCSN dz dE ⌫ e Z ⌫ See, e.g., reviews by Beacom (2010), Lunardini (2010)
Input 2: core-collapse rate (intensely studied by astronomers using photons, rapidly improving)
Input 3: neutrino detector capabili es (well understood for H2O) ⌫¯ + p e+ + n e ! Elba XIV Horiuchi (Virginia Tech) 29 Input 1: Time-integrated neutrino signal
Neutrino emission: Black hole cuts off the neutrino emission, but it necessarily goes through rapid mass accre on à ν emission is more luminous and ho er (EOS dependent)
Liebendoerfer et al 2004, Fischer et al 2009, Sumiyoshi et al 06, 07, 08, 09, Nakazato et al 2008, 2010, O’Connor & O 2011, …
Elba XIV Horiuchi (Virginia Tech) 30 Input 2: cosmic core-collapse rate Core-collapse rate From the birth rate of
10 massive stars ]
-3 Observed supernova rate Birthrate of massive stars Derived from observa ons Mpc
-1 of luminous supernovae
yr (many recent updates) -4 Rate of bright collapse (Core-collapse rate) – 1 (supernova rate) = DIM or DARK collapse rate Li et al. (2010b) Cappellaro et al. (1999) Approximately 30 – 50 % Botticella et al. (2008) • Some of this can be due to rate density [10 Cappellaro et al. (2005) Bazin et al. (2009) collapse to black holes. Dahlen et al. (2004) • Other possibili es include 0.1 0 0.2 0.4 0.6 0.8 1.0 ONeMg collapse, dust Redshift z (especially from mass loss), Horiuchi et al (2011) fall back intense collapse,
Elba XIV Horiuchi (Virginia Tech) etc 31 Predic ons Diffuse neutrino fluxes: Event spectra with uncertain es: Assuming 30% collapse to black holes
Black holes
Neutron stars à
Lunardini (2009); Lien et al (2010),Keehn & Lunardini (2010), Nakazato (2013), Yuksel & Kistler (2014) Event rate at SK (22.5 kton FV): Spectrum 18 MeV threshold [/yr] 4 MeV 0.4 +/- 0.1
4 MeV+BH < 1.8 Adapted from Horiuchi et al (2009) SN1987A 0.5 +/- 0.1
Elba XIV Horiuchi (Virginia Tech) 32 Searches and forecast
Background-limited: R&D towards a signal-limited regime Significant backgrounds at present: Use dissolved Gadolinium (Gd) for effec ve neutron-tagging Beacom & Vagins (2004) ⌫¯ + p e+ + n e ! current with Gd Capture on Capture on Gd, protons, signal provides a coincidence lost signal à Opens an event limited search à Increases energy window
Spectrum 18 MeV 10 MeV threshold [/yr] threshold [/yr] 4 MeV 0.4 +/- 0.1 1.8+/- 0.5 4 MeV+BH < 1.8 < 4.5 Beacom 2010, from SK limits (Malek et al 2003, for update see Bays et al 2012) SN1987A 0.5 +/- 0.1 1.5 +/- 0.5 Elba XIV Horiuchi (Virginia Tech) 33 Summary
Take away messages:
1. Simula ons are exploding! Systema c simula ons are revealing that compactness is a useful parameter to characterize the diversity of core- collapse simula ons.
2. Observa onally, the frac on of collapse to black holes may be as high as ~ 30% of core collapse. This would explain: • The red supergiant problem • The black hole mass func on • The supernova rate discrepancy • Recent results from Survey about Nothing
3. Neutrinos provide a valuable test, both via the next Galac c supernova, and via the diffuse supernova neutrino background. (Survey About Nothing will provide important informa on also)
Thank you!
Elba XIV Horiuchi (Virginia Tech) 34