1. Determining the neutrino hierarchy from a galactic supernova using a next-generation detector David M. Webber APS April Meeting May 3, 2011 SN 1572 “Tycho’s Nova” 7,500 light years (2.3 kPc) SN 1604 “Kepler’s Nova” ~20,000 light years (6 kPc) http://www.spitzer.caltech.edu/search/image_set/20?search=sig08-016http://chandra.harvard.edu/photo/printgallery/2004/ Cassiopeia A ~300 years ago 11,000 light years (3.4 kPc) http://www.spitzer.caltech.edu/search/image_set/20?search=ssc2005-14c 1

2. Adapted from Fuller, NDM09 Neutrino emission: 10% gravitational binding energy L ~ 10 51 -10 53 erg s -1 10-30 seconds Neutrino spectral swaps 2D. M. Webber

3. Initial neutrino spectra “Pinched thermal” distribution 1 e “freeze-out” later than , , at lower temp Initial Spectrum will be modified by – Spectral (flavor) swaps – Turbulence and shockwave – Detector resolution 1 Keil, Raffelt, Janka. Astrophys. J. 590,971(2003) Ignore 3 Fig adapted from: Duan and Friedland, Phys. Rev. Lett. 106, 091101 (2011) 060 MeV D. M. Webber

4. The initial flux is modified by spectral swaps ● Near the Supernova, at high neutrino densities, neutrinos self-interact ● Self-interaction will introduce a collective flavor swap e>e> x>x>  x >+  e >  e >+  x > 060 MeV0 Normal Hierarchy Fig adapted from: Duan and Friedland, Phys. Rev. Lett. 106, 091101 (2011)

5. The features of the flavor swap depend on the neutrino hierarchy http://www.lbl.gov/Science-Articles/Archive/sabl/2006/Jul/03.html The energy shape gives a handle on the hierarchy       5 060 MeV Normal Hierarchy “Normal”“Inverted” Inverted Hierarchy Energy spectra figs adapted from: Duan and Friedland, Phys. Rev. Lett. 106, 091101 (2011)

6. Next-generation detectors will see lots of (anti)neutrinos from a galactic SN Fig: S. Kettell Fig: Steve Hentschel Via Bruce Baller LBNE Water-Cherenkov 100 kT 10 kPc to supernova ~20000 events LBNE Liquid Argon 17 kT 10 kPc to supernova ~1500 events SN 1987A 160,000 LY (50 kPc) (galactic SN 5-15 kPc) Kamiokande II (1 kton) detected 11 IMB (3.3 kton) detected 8 Baksan (0.2 kton) detected 5 http://hubblesite.org/newscenter/archive/releases/1995/49/image/a/ How many events are needed to distinguish the neutrino hierarchy? 6D. M. Webber

7. reaction cross-sections Dominant reaction: WaterArgon Dominant reaction: 7 Cross-section (10 -38 cm 2 ) 10 2 10 -7 10 2 Neutrino Energy (MeV) 10 -7 10010 10010 inverse beta decay elastic scattering e 16 0 elastic scattering Cross-section (10 -38 cm 2 ) NC 16 0 e 40 Ar D. M. Webber http://www.int.washington.edu/PROGRAMS/10-2b/LBNEPhysicsReport.pdf SNOwGLoBES K. Scholberg L11 6

8. Observed spectral shapes Larger detector, more eventsSharper, nonthermal features Normal Hierarchy Inverted Hierarchy Water 100kT Argon 17kT 8 Normal Hierarchy Inverted Hierarchy Events/0.5 MeV/s* Energy (MeV) * one-second late-time slice D. M. Webber

9. A log-likelihood ratio discriminates between neutrino hierarchies 10% 12.6  9 log likelihood NH – log likelihood IH 1000 events “Normal” 1000 events “Inverted” 1000 simulated spectral fits Define “significance (  )” as hierarchy distinguishability *fit assuming known spectrum D. M. Webber

10. 10 Finding the required number of events to distinguish the neutrino hierarchy *fit assuming known spectrum Significance (  ) D. M. Webber

11. 189 events in argon 11D. M. Webber Normal HierarchyInverted Hierarchy

12. 12 Finding the required number of events to distinguish the neutrino hierarchy *fit assuming known spectrum Significance (  ) D. M. Webber

13. 1645 events in water 13D. M. Webber Normal HierarchyInverted Hierarchy

14. 14 Finding the required number of events to distinguish the neutrino hierarchy *fit assuming known spectrum Significance (  ) D. M. Webber

15. 15 1014 events in water, 76 events in argon water normal hierarchy water inverted hierarchy argon normal hierarchy argon inverted hierarchy

16. Fitting simultaneously is better than fitting separately 16 *fit assuming known spectrum Significance (  ) D. M. Webber SN Distance from Earth, O(10’s kPc)

17. Summary Core-collapse supernovae emit a lot of neutrinos Spectra will not be known ab-initio ~40% chance to observe a galactic supernova in next-gen detectors Non-thermal features in the observed energy-spectrum will distinguish hierarchy Water and argon detectors, fit simultaneously, will give the most information Further study – More neutrino flux models – Time-evolution of neutrino flux – Parameterize uncertainty 17 http://chandra.harvard.edu/photo/2008/g19/ G1.9+0.3 circa 1870* 25,000 light years away (7.7 kPc) *City of Anaheim, CA incorporated Feb 10, 1870. D. M. Webber

18. Backup

19. Fitting simultaneously is better than fitting separately 19 *fit assuming known spectrum Crab Nebula (SN1054)galactic centerMilky Way diameter SN1987A most probable distance Significance (  ) D. M. Webber SN Distance from Earth, O(10’s kPc)

20. To study different SNB spectra, need “effective” spectra generator ● Use basis: ( e, e, x, x, y, y ) ● x =cos(  23 )  -sin(  23 )  ● y =cos(  23 )  +sin(  23 )  ● Tunable Knobs: ● Relative flavor luminosity, eg. L( e )/L( e ), L( x ) /L( e ) ● Average Energies, Luminosity: (1.0, 1.0, 1.5, 1.5, 1.5, 1.5) (MeV): (12, 15, 20, 20, 20, 20) 20D. M. Webber

21. Miscellaneous Supernova – 10% of rest energy emitted – 99% of energy emitted as neutrinos Caveats – Neglected Turbulence – Assumed energy spectrum known exactly – Have not explored time-dependence Distances – Milky Way is 30 kPc across – Sun is 8.5 kPc from center of Milky Way Energy resolution – 10-12% for water from 10-100 MeV (docDB 2687) – 15% PMT coverage 21D. M. Webber

22. A more robust estimator uses log likelihood Water Detector 30% PMT coverage HQE tubes IBD reaction 10% 14.5  22D. M. Webber

23. Slide created by: Fuller, NDM09 23D. M. Webber

24. Galactic supernovae occur roughly twice per century YEAR AD CONSTELLATION name VISIBILITY period BRIGHTNESS magnitude REMNANT feature DISTANCE (l.y.) 185Centaurus20 months-6?G315.4-2.37500 386Sagittarius3 months?G11.2 -0.3?15000 393Scorpius8 months?G348.7 +0.3?? 1006LupusFew years-9P 1459 -417000 1054Taurus24 months-5Crab Nebula6500 1181Cassiopeia6 months+1?3C5810500 1572Cassiopeia18 months<-1 Tycho's SN 3C10 8000 1604Ophiuchus12 months-3Kepler's SN9500 1667CassiopeiaNot seen>4?Cass-A11000 1870SagittariusNot seen>5?G1.9+0.328000 http://www.spaceacademy.net.au/watch/snova/galactic.htm http://chandra.harvard.edu/photo/2008/g19/ G1.9+0.3 ~1870* 25,000 light years (7.7 kPc) Known galactic supernovae in the last 2000 years *City of Anaheim, CA incorporated Feb 10, 1870. Core-Collapse Supernova rate From 26 Al abundance: 1.9 +/- 1.1 per century Diehl et. al., Nature 439 ~40% chance to see SN with next-gen detector, even if optically invisible. 24D. M. Webber

25. 25 Fig 4 from Duan and Friedland, Phys. Rev. Lett. 106, 091101 (2011) D. M. Webber