1 / 25

The Diffuse Flux of Supernova Neutrinos

F n. The Diffuse Flux of Supernova Neutrinos. Cecilia Lunardini Institute for Nuclear Theory University of Washington - Seattle. Colliders to Cosmic Rays 2007 , Lake Tahoe, CA. Abstract. Diffuse neutrinos from supernovae O(1) question: Seen? Not yet BUT: will be seen

sora
Download Presentation

The Diffuse Flux of Supernova Neutrinos

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fn The Diffuse Flux of Supernova Neutrinos Cecilia Lunardini Institute for Nuclear Theory University of Washington - Seattle Colliders to Cosmic Rays 2007 , Lake Tahoe, CA

  2. Abstract • Diffuse neutrinos from supernovae • O(1) question: Seen? • Not yet • BUT: will be seen • O(e) question: What can we learn? • original n spectrum (at emission)

  3. How do stars die? Supernovae • Massive stars (M>8Msun) gravitational instability • Collapse to nuclear density core • Shock and explosion http://chandra.harvard.edu/resources/animations/

  4. A neutrino phenomenon • 99% of the gravitational energy in neutrinos • GN M2f/rf - GN M2i/rI ~ 1053 ergs • Diffusion from thermal surface • e, , , anti-e, anti-, anti- • Time : (size2)/(mean free path) ~ 10 s • h E i : ~9 – 22 MeV, h Eei < h Eanti-ei < h Exi x=,

  5. The diffuse flux • Cosmological SN rate: RSN(0) ~ 10-4 Mpc-3yr-1

  6. Fit to core collapse SN data only, C.L., astro-ph/0509233 Star Formation fit, Beacom & Hopkins, astro-ph/0601463 Data: Cappellaro et al., A&A 430, 2005; Dahlen et al., APJ 613 2004 (3 extinction-corrected, 1 not corrected) Confidence levels: 68.3,90,95.4%

  7. “Effective” neutrino spectrum after oscillations: • a (“pinching”)~ 2-4 , E0~ 12 - 20 MeV SN1987A-motivated, Mirizzi & Raffelt, PRD72, 2005

  8. Predictions SK limit Ando & Sato F(E>19.3 MeV)/(cm-2 s-1) Kaplinghat et al. Hartmann & Woosley Strigarietal. Lunardini

  9. Seen? Not yet! Limits: anti-ne, ne KamLAND SNO SK+oscillations, Lunardini, PRD73, 2006 F(E)/(MeV-1cm-2 s-1) SuperKamiokande Atmospheric n, invisible m Zhang et al. (Kamiokande) PRL61, 1988; Eguchi et al. (KamLAND),PRL92, 2004; Malek et al. (SK), PRL90, 2003; Aharmim et al., (SNO), PRD70, 2004; Aglietta et al. (LSD), Astrop. Phys. 1, 1992, Aharmim et al., (SNO), hep-ex/0607010, 2006

  10. BUT: will be seen at Mton detectors Anti-e + p  n + e+ Beacom & Vagins, PRL93, 2004 Fogli et al., hep-ph/0412046

  11. Most conservative, C.L., astro-ph/0509233 See also Ando & Sato, New J. Phys., 2004; Fogli et al., JCAP, 2005; Marrodan Undagoitia et al., Prog. Part. Nucl. Phys. 57, 2006 ; Cocco et al. JCAP 0412:002,2004

  12. What can we learn? • Spectrum of e+: • E0 , a (“pinching”), b (SNR power) • Number of e+ events: • Le , RSN(0), E0, a , b

  13. Spectral sensitivity Water only • Original  spectrum? • Yes! • Useful observable: (bin 1)/(rest) • Supernova Rate? • No/difficult Normalized to 60 events C.L., astro-ph/0612701

  14. Water+Gd Normalized to 150 events C.L., astro-ph/0612701

  15. To understand: analytics • Approximations: dominated by z<1 at high energy (redshift): • RSN=0 z>1 • z<<1 & Wm + WL = 1:

  16. Result: h = a + b - (3/2)Wm , zmax=1 • Cruder : neglect upper integration limit • e = E0/(1+a), b only in the polynomial part! • Crudest: “fitted” exponential: F = F0 e-E/<E>

  17. R(0)=10-4 Mpc-1yr-1 , Le=5 1052 ergs, b = 3.28 , a=2.6 E0 =15 MeV • Exact • Result • Cruder (20% accuracy above 20 MeV) • neglect upper integration limit • Crudest • “fitted” exponential

  18. Numbers of events add information • events/4 year • (bin 1)/(rest) R(0)=10-4 Mpc-1yr-1 , Le=5 1052 ergs, 0.4 Mt, 4 yr

  19. Conclusions: likely scenario • Gadzooks and/or LENA and/or HyperK/UNO/MEMPHYS will see the DF • b known from SN surveys (SNAP, JWST) • DF spectrum -> E0 , a • Test of SN numerical models • DF number of events -> break degeneracy between E0, a, Ln, RSN(0) http://snap.lbl.gov/ http://www.jwst.nasa.gov/,

  20. Backup slides

  21. Original n spectrum? YES! C.L., astro-ph/0612701 Normalized to 60 events, b=3.28 Total error, no Gd Total error, with Gd

  22. e/MeV=2 (E0/MeV=12, a=5) e/MeV=4.2 (E0/MeV=15, a=2.6) e/MeV=6.7 (E0/MeV=20, a=2) Original n spectrum? YES! Normalized to 60 events, b=3.28 • Depends on e = E0/(1+a)

  23. Original n spectrum? YES! Normalized to 60 events, b=3.28 • Useful observable: first bin/rest of data

  24. SN population? ..no.. Normalized to 60 events, E0/MeV=15, a=2.6 b=5 b=3.28 b=2

  25. e~ 7 Number of events add information R(0)=10-4 Mpc-1yr-1 , Le=5 1052 ergs, 0.4 Mt, 4 yr, Eth=18 MeV

More Related