The Diffuse Supernova Neutrino Background

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The Diffuse Supernova Neutrino Background
Louie Strigari The Ohio State
University
Collaborators John Beacom, Manoj Kaplinghat,
Gary Steigman, Terry Walker, Pengjie Zhang
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The Plan

• Diffuse Supernova Neutrino Background
• Theoretical Prediction
• Experimental Limits and Detection Prospects
• Sampling Flavors of the DSNB
• MeV Neutrino and Gamma-Ray Astronomy
• Return to the Crime Scene SN 1987A

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DSNB The Big Picture
Core Collapse of Massive Star
Gives Burst of 1058 Neutrinos

Massive Star Formation Since z 6

The Diffuse Supernova Neutrino Background (DSNB)
Cosmological background of neutrinos from all
supernovae that have occurred
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Evolution of Massive Stars (gt 8
Solar Mass)
Optical SNII
or
Black Hole
Main Sequence Burning 10-100 Myr
Core Collapse 3 x 1053 ergs
released in 10 seconds
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Evolution of Intermediate Mass Stars
(3-8 Solar Mass)
SNIa (Fe)
Main Sequence, Binary
Accreting White Dwarf
t Gyr
t Gyr
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Cosmic Star Formation Rate

• UV luminosity density ß 2.5
• Galaxy Surveys ß 2-4 SDSS, 2df

zp 1 a 0-2
D. Schiminovich et al. (2005)
supernova rate stellar mass function x star
formation rate
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DSNB Flux Theoretical Predictions
Increase in High Redshift Star Formation
Best Estimate Model
Lower bound from Astronomy Data
Supernova Neutrino Spectrum
Impact of Oscillations
Dighe Smirnov 2003, Minakata et al. 2002
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DSNB Detection
Event Rate of targets x cross section
x flux
Largest Yield from Inverse Beta
Super-Kamiokande (22.5 kton)
1.5 x 1033
Invisible
Visible
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Backgrounds to Detection
Atmosphere
Below 50 MeV, Muon is Invisible
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DSNB Event Rate Predictions

• 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 Reduction
• Beacom Vagins 2004

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Super-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
  years
• Strigari, Kaplinghat, Steigman, Walker 2004

Super-Kamiokande Collaboration, PRL 90, 061101
(2003)
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Gadolinium Enhanced Super-K (GADZOOKS!)
The Idea
Addition of Gadolinium Trichloride to Water
Cerenkov Detectors
The Benefits
Flux

• Neutron Tagging
• Reduction of Invisible Muon Background
• Lower Energy Threshold for DSNB Detection

Threshold Energy
Strigari, Kaplinghat, Steigman, Walker 2004
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DSNB Scorecard
Detector Channel Energy Window Flux Limit
Super-K 19 - 83 1.2
KamLAND 8 - 14 102
Mont Blanc 25 - 50 104
SNO 21 - 31 10
Neutrino Energies in MeV Fluxes in cm-2 s-1
Beacom Strigari (in prep.) Predicted Liquid
Argon flux limit 1.6 cm-2 s-1
(Cocco,
Ereditato, Fiorillo, Mangano, Pettorino 2004)
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DSNB Detection Channels
Super-K (H20)
SNO (D2O)
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DSNB Constrains from SNO

• Solar background lt 20 MeV

• Invisible Muon Background

• DSNB Electron Neutrino Flux Limit at SNO

Beacom Strigari (in prep)
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MeV Neutrino and Gamma-Ray
Astronomy
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Constraining the Cosmic Star Formation Rate

• Shaded Region- SDSS, 2dF
• Curves- models based on UV, IR luminsity
• DSNB is the strongest constraint on the massive
  Star Formation Rate
• Fukugita Kawasaki 2003
• Ando 2004

Concordance Region
Strigari, Beacom, Walker, Zhang, JCAP04(2005)017
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Cosmic Supernova Rates

• 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?

Strigari, Beacom, Walker, Zhang, JCAP04(2005)017
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Cosmic Gamma-Ray Background(CGB)

• CGB Sources
• lt 1 MeV Seyferts
• gt 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?

Strigari, Beacom, Walker, Zhang, JCAP04(2005)017
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Additional Physics with the DSNB

• Constraints on Neutrino Properties
• Neutrino Decay
  Ando 2003
  
  Fogli, Lisi, Mirizzi, Montanino
  2004
• Mini Z Burst Goldberg, Perez,
  Sarcevic 2005

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Supernova Neutrinos from Nearby Galaxies?

• Detection potential with megaton detectors
• Correlate with optical SNII for the detection of
  1 event
• 2 event detection essentially background free

Ando, Beacom, and Yuksel 2005
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Return to the Crime Scene Supernova 1987A
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Historical Supernovae
You can observe a lot just by watching

Yogi Berra
Supernova Rate in the Milky Way 1 per
century One identified nearby supernova in
telescopic era SN 1987A
Stephenson and Green (2002)
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A Blast from the PastSupernova 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?

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Constraining Flavor Emission

• DSNB flux limit at SNO can constrain electron
  neutrino flux from SN 1987A
• Was the electron neutrino flux larger than
  expected? e.g. Costantini, Ianni,
  Vissani 2004
• SNO limit more sensitive to higher electron
  neutrino temperatures

Beacom Strigari (in prep)
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Conclusions

• 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