The Diffuse Supernova

Neutrino Background

Louie Strigari The Ohio State

UniversityCollaborators: John Beacom, Manoj Kaplinghat, Gary Steigman, Terry Walker, Pengjie Zhang

The PlanThe Plan

Diffuse Supernova Neutrino Diffuse Supernova Neutrino BackgroundBackground Theoretical PredictionTheoretical Prediction Experimental Limits and Detection Experimental Limits and Detection

ProspectsProspects Sampling Flavors of the DSNBSampling Flavors of the DSNB MeV Neutrino and Gamma-Ray MeV Neutrino and Gamma-Ray

AstronomyAstronomy Return to the Crime Scene: SN 1987AReturn to the Crime Scene: SN 1987A

DSNB: The Big PictureDSNB: The Big Picture

Core Collapse of Massive Star Core Collapse of Massive Star Gives Burst of Gives Burst of

~ 10~ 105858 Neutrinos Neutrinos

Massive Star Formation Since z Massive Star Formation Since z ≤ 6≤ 6

==

++

The Diffuse Supernova Neutrino Background (DSNB) – Cosmological background of neutrinos from all supernovae that have occurred

Evolution of Massive Stars Evolution of Massive Stars (> 8 Solar Mass) (> 8 Solar Mass)

Main Sequence Main Sequence Burning: 10-Burning: 10-

100 Myr100 Myr

Core Collapse: Core Collapse: 3 x 10 3 x 105353

ergs released in ergs released in ~10 seconds~10 seconds

Optical Optical SNIISNII

oror

Black Black HoleHole

Main Sequence, Binaryt ~ Gyr

Accreting White Dwarft ~

Gyr

SNIa (+Fe)

Evolution of Intermediate Evolution of Intermediate Mass Stars (3-8 Mass Stars (3-8

Solar Mass)Solar Mass)

Cosmic Star Formation Cosmic Star Formation RateRate

D. Schiminovich et al. (2005)

• UV luminosity density β ~ 2.5

• Galaxy Surveys β ~ 2-4 SDSS, 2df

zp ~ 1

α ~ 0-2

supernova rate = [stellar mass function] x [star formation rate]

DSNB Flux Theoretical DSNB Flux Theoretical PredictionsPredictions

Increase in High Redshift Star Formation

Best Estimate ModelLower bound from Astronomy Data

Supernova Neutrino Spectrum

Impact of Oscillations:Dighe & Smirnov 2003, Minakata et al. 2002

DSNB DetectionDSNB Detection

Event Rate = [ # of targets ] x [ cross section ] x [ flux ]

Largest Yield from Inverse Beta

1.5 x 1033

Visible

Invisible

Super-Kamiokande (22.5 kton)

Backgrounds to Backgrounds to DetectionDetection

Below ~ 50 MeV, Muon is InvisibleBelow ~ 50 MeV, Muon is Invisible

AtmosphereAtmosphere

DSNB Event Rate DSNB Event Rate PredictionsPredictions

• Modern predictions for Super-K: ~ 3 events/yr above 18 MeV ~ 6 events/yr above 10 MeV

Ando, Sato & Totani 2003

Fukugita & Kawasaki 2003

Strigari, Kaplinghat, Steigman & Walker 2004

• Atmospheric Background ReductionBeacom & Vagins 2004

Super-Kamiokande Collaboration, PRL 90, 061101 (2003)

Super-K Upper LimitSuper-K Upper Limit

• 4+ years of data gives flux limit: 1.2 cm-2 s-1

• Detection signature is an excess of events

• Detection timescale with fiducial model is ≈ 9 yearsStrigari, Kaplinghat, Steigman, Walker 2004

Gadolinium Enhanced Gadolinium Enhanced Super-K (GADZOOKS!)Super-K (GADZOOKS!)

• Neutron TaggingNeutron Tagging

• Reduction of Invisible Muon Reduction of Invisible Muon BackgroundBackground

• Lower Energy Threshold for Lower Energy Threshold for DSNB Detection DSNB Detection

Flu

xF

lux

Threshold Threshold EnergyEnergyStrigari, Kaplinghat, Steigman,

Walker 2004

The Idea:Addition of Gadolinium Trichloride

to Water Cerenkov Detectors

The Benefits:

DSNB ScorecardDSNB Scorecard

DetectorDetector ChannChannelel

Energy Energy WindowWindow††

Flux Flux LimitLimit‡‡

Super-KSuper-K 19 - 8319 - 83 1.21.2

KamLANDKamLAND 8 - 14 8 - 14 ~10~1022

Mont Mont BlancBlanc

25 - 50 25 - 50 ~10~1044

SNOSNO## 21 - 3121 - 31 ~10~10† † Neutrino Energies in MeVNeutrino Energies in MeV

‡ ‡ Fluxes in cmFluxes in cm-2-2 s s-1-1

## Beacom & Strigari (in prep.) Beacom & Strigari (in prep.)

## Predicted Liquid Argon flux limit: 1.6 cm Predicted Liquid Argon flux limit: 1.6 cm-2-2 s s-1-1 (Cocco, Ereditato, Fiorillo, (Cocco, Ereditato, Fiorillo, Mangano, Pettorino 2004) Mangano, Pettorino 2004)

DSNB Detection ChannelsDSNB Detection Channels

Super-K (H20)

SNO (D2O)

DSNB Constrains from DSNB Constrains from SNOSNO

Beacom & Strigari (in prep)

• Solar background < 20 MeV

• Invisible Muon Background

• DSNB Electron Neutrino Flux Limit at SNO

MeV Neutrino and MeV Neutrino and Gamma-Ray Astronomy Gamma-Ray Astronomy

• Shaded Region- SDSS, 2dF

• Curves- models based on UV, IR luminsity

• DSNB is the strongest constraint on the massive Star Formation Rate Fukugita & Kawasaki 2003Ando 2004

Concordance Region

Strigari, Beacom, Walker, Zhang, JCAP04(2005)017

Constraining the Cosmic Constraining the Cosmic Star Formation RateStar Formation Rate

• Test supernova progenitor models

• What fraction of core-collapse SNII fail?

• What is the average delay time between the formation of a binary star system and a SNIa event?

Cosmic Supernova RatesCosmic Supernova Rates

Strigari, Beacom, Walker, Zhang, JCAP04(2005)017

• CGB Sources

< 1 MeV: Seyferts

> 10 MeV: Blazars

1-3 MeV: SNIa

• Concordance model constrains SNIa contribution to the CGB

• What are the sources of the 1-3 MeV CGB?

Cosmic Gamma-Ray BackgroundCosmic Gamma-Ray Background(CGB)(CGB)

Strigari, Beacom, Walker, Zhang, JCAP04(2005)017

Additional Physics with the Additional Physics with the DSNBDSNB

Constraints on Neutrino PropertiesConstraints on Neutrino Properties Neutrino Decay Neutrino Decay

Ando 2003 Ando 2003 Fogli, Lisi, Mirizzi, Montanino Fogli, Lisi, Mirizzi, Montanino 20042004

Mini Z Burst Mini Z Burst Goldberg, Perez, Sarcevic 2005Goldberg, Perez, Sarcevic 2005

Supernova Neutrinos from Supernova Neutrinos from Nearby Galaxies? Nearby Galaxies?

Ando, Beacom, and Yuksel 2005

• Detection potential with megaton detectors

• Correlate with optical SNII for the detection of 1 event

• 2 event detection essentially background free

Return to the Crime Scene: Return to the Crime Scene: Supernova 1987ASupernova 1987A

Historical SupernovaeHistorical Supernovae

Supernova Rate in the Milky Way ≈ 1 per centurySupernova Rate in the Milky Way ≈ 1 per century

One identified nearby supernova in telescopic era: One identified nearby supernova in telescopic era: SN 1987ASN 1987A

Stephenson and Green Stephenson and Green (2002)(2002)

“You can observe a lot just by watching’ –Yogi Berra

A Blast from the Past:A Blast from the Past:Supernova 1987ASupernova 1987A

• 19 neutrinos detected by IMB and Kamiokande

• Consistent with core collapse energy budget

• What was the flavor content of the flux?

• Why were a majority of the events forward?

Constraining Flavor Constraining Flavor EmissionEmission

• DSNB flux limit at DSNB flux limit at SNO can constrain SNO can constrain electron neutrino flux electron neutrino flux from SN 1987Afrom SN 1987A

• Was the electron Was the electron neutrino flux larger than neutrino flux larger than expected? expected? e.g. e.g. Costantini, Ianni, Vissani 2004 Costantini, Ianni, Vissani 2004

• SNO limit more sensitive SNO limit more sensitive to higher electron neutrino to higher electron neutrino temperaturestemperatures

Beacom & Strigari (in prep)

ConclusionsConclusions

DSNB: First Detection of Neutrinos Beyond SN1987A?

Current DSNB Limits Constrain the Cosmic Star Formation Rate (CSFR)

Measurements of the CSFR in Agreement with Supernova Rates

DSNB + SN1987A can constrain supernova neutrino emission