Diffuse supernova neutrinos at underground laboratories Cecilia Lunardini Arizona State University And RIKEN BNL Research Center INT workshop “Long-Baseline Neutrino Physics and Astrophysics”

Motivations Current status The future: –Detection potential –What can we learn? Extras: what else? C. Lunardini, arXiv: (review)

Diffuse neutrinos from all SNe Sum over the whole universe: Supernovae S. Ando and K. Sato, New J.Phys.6:170,2004.

Motivations Clip art from M. Vagins

Sooner and more Faster progress –Alternative to a galactic SN! ~20 events/yr/Mt  everyday physics! New science –What’s typical ? –New/rare SN types –Cosmological Sne Physics in the MeV window?

Current status

The “ingredients” Cosmological rate of supernovae Neutrino flux at production + Propagation effects: Oscillations Redshift …. Neutrino flux at production + Propagation effects: Oscillations Redshift …. Cosmology

Supernova rate R SN (z) ~R SN (0) (1+z) β, z<1 normalization uncertain This work: β=3.28, R SN (0) = Mpc -3 yr -1 Beacom & Hopkins, astro-ph/ From Star Formation Rate From SN data

Original spectra Models: –Lawrence Livermore –Thompson, Burrows, Pinto (Arizona) –Keil, Raffelt, Janka (Garching) ergs, equipartitioned between 6 species Keil,, Raffelt,Janka, 2003 Astrophys. J x=μ, τ

Flavor oscillations Self-interaction + MSW (H) + MSW (L) –Spectral swap Depend on θ 13 and hierarchy –Normal (inverted): ∆m 2 31 >0 (∆m 2 31 <0) Jumping probability, P H Duan, Fuller, Quian, PRD 74, 2006 C.L. & A. Y. Smirnov, JCAP 0306, 2003

p= 0 – 0.32, p = 0 – 0.68 Chakraborty et al., hep-ph/ Higher energy tail

DSNnF spectrum Exponential decay with E LL TBPKRJ C.L., in preparation

Upper limits and backgrounds Energy window SuperKamiokande (Malek et al., PRL, 2003): Red dashed: Homestake Solid, grey: Kamioka

anti- e flux: predictions C.L., Astropart.Phys.26: ,2006

The future: detection potential

Detection technologymassReactionEnergy window Events/( 5 yrs) Water Cherenkov 0.4 MtAnti-nue, inverse beta, (90% eff.) 19 – 40 MeV Water + Gadolinium (GADZOOKS) MtAnti-nue, inverse beta (90% eff.) 11 – 40 MeV Liquid Argon0.1 Mtnue + Ar, CC (100% eff.) 19 – 40 MeV6 – 28 Liquid Scintillator (LENA) 50 ktAnti-nue, inverse beta (100% eff.) 11 – 40 MeVO(10)

Water Energy window Background/signal ~ 5 -6 (at Kamioka) Fogli et al., JCAP 0504, 002, 2005 Background/signal ~ 5 -6 (at Kamioka) Fogli et al., JCAP 0504, 002, 2005 Bulk of events missed Large statistics: ~ 1- 2 events/MeV/yr

GADZOOKS Energy window Background/signal<1 Invisible muons reduced to 1/5 Beacom & Vagins, PRL93, 2004 Background/signal<1 Invisible muons reduced to 1/5 Beacom & Vagins, PRL93, 2004 Larger energy window: Bulk of events captured! Larger energy window: Bulk of events captured! Modest statistics… Scaling to Mt??

LAr Energy window Background/signal ~ Bulk of events may be captured! Statistics modest: ~0.2 events/yr/MeV Scaling? Statistics modest: ~0.2 events/yr/MeV Scaling? C.L., in preparation

What can we learn?

Water+Gd: effective spectrum Normalized to 150 events,  =3.28 C.L., Phys.Rev.D75:073022,2007

A step beyond SN1987A! Test SN codes of spectra formation, some oscillation effects, etc. 0.1 Mt yr : –Tests part of parameter space –May not reach SN1987A region 0.1 Mt yr Yuksel, Ando and Beacom, Phys.Rev.C74:015803,2006

Chance to test  r ~ 0.6 – 0.9 Normalized to 150 events C.L., Phys.Rev.D75:073022,2007

New SN types: failed SNe M > 40 Msun, 9-22% of all collapses Direct BH-forming collapse (no explosion): –Higher energies: E 0 ~ 20 – 24 MeV For all flavors Due to rapid contraction of protoneutron star before BH formation –Electron flavors especially luminous (e - and e + captures) Liebendörfer et al., ApJS, 150, 263, K. Sumiyoshi et al., PRL97, (2006), T. Fischer et al., (2008), , K. Nakazato et al., PRD78, (2008)

–Progenitor: M=40 M sun, from Woosley & Weaver, 1995 –“stiffer” eq. of state (EoS)  more energetic neutrinos Shen et al. (S) EoS BH NS K. Nakazato et al., PRD78, (2008)

Number of events: water.. Best case scenario: 22% failed, S EoS Total Normal Failed C.L., arXiv: , Phys. Rev. Lett., 2009, J. G. Keehn and C.L., in preparation

LAr Bulk of events from failed SNe captured Failed SN at least a 10% effect in energy window J. Keehn & C.L., in preparation Failed Normal Total

Reducing uncertainties Precise SN rates coming soon from astronomy Neutrino uncertainties more serious –SN modeling? –Galactic SN?

C.L., Astropart.Phys.26: ,2006

Extras What else is there?

Neutrinos from solar flares? LSD: 27 flares examined in 3 years Mt-size advocated for detection Relic SN, 1 year Flare, best Flare,conservative Erofeeva et al., 1988; Bahcall PRL 1988 Kocharov et al., 1990, Fargion et al., 2008 Aglietta et al., 1990 Miroshnichenko et al., Space Science Reviews 91: 615–715, 2000

Solar antineutrinos Spin-flavor oscillations –ν e  anti-ν e Rashba & Raffelt, Phys.Atom.Nucl.73: ,2010

Neutrinos from relic decay/annihilation χ  ν + anti-ν χ+ χ  ν + anti-ν Gamma rays Yuksel & Kistler, PRD, 2007 Palomares Ruiz & Pascoli, Phys.Rev.D77, 2008 Palomares Ruiz, Phys.Lett.B,2008

MeV Dark Matter absorption Kile and Soni, Phys.Rev.D80:115017,2009

Summary DSNnF may be seen with few years running! –100 kt LAr : O(10) events –0.4 Mt water : O(10 2 ) events New science: –Typical neutrino emission –Sensitive to failed Sne –Other physics in energy window? To advance further: –Resolve parameter degeneracies (theory) –reduce background at low E