1. Detecting a Galactic Supernova with H2 or GEO
P.H. for the LSC-Virgo Burst Group
Expected rate for SN (type 2) events:
~ 2 / century in the Milky Way
Expected signals:
- GW
- neutrinos
- photons
Chronology:
- collapse
- bounce
- GW emission (~ coincident with the bounce)
- neutrino flash ( slightly delayed wrt GW)
- thermal neutrinos
- photons (delayed by hours) => useless
Scenario: detection of neutrinos (SK, SNO …) from a Galactic SN and search
for a coincident event in a GW detector.
=> How neutrinos can improve a SN event detection

2. Timing GW-bounce
Average over the Zwerger&Mueller catalogue (78 waveforms):
Dt GW-bounce ~ 0.1 +/- 0.4 ms
Accuracy penalized by “type 3” waveforms (type 3 disappeared in recent work)
Type 3
Zwerger and Mueller, 1997.
Dimmelmeir, Ott et al., 2007.

3. Neutrino emission Neutronization flash (electron neutrinos)
- release ~ a few 1044 J
- duration sflash ~ 2.3+/-0.3 ms.
- => luminosity ~1048 W
Thermal emission (n`n pairs)
- 99% energy, up to 5x1045 J / neutrino type
- En ~10-20 MeV

4. (if GW peak detected par Gaussian templates exp(-t 2 / 2t 2) )
Delay GW-neutrinos (I)
Statistical errors on arrival times
Neutrinos: For a 10 kpc, Ne ~10 (SK or SNO)
- Gravitational waves:
(if GW peak detected par Gaussian templates exp(-t 2 / 2t 2) )
Assuming Ne =10, t = 2ms and SNR=5:

5. Delay GW-neutrinos (II)
Systematic error on arrival time:
Supernova models :
Dt GW-bounce ~ /- 0.4 ms (Z&M)
Dt nflash-bounce ~ /- 0.5 ms (Z&M and DFM)
Get rid of the bounce time reference -> relative delay between GW and n flash:
Dt nflash-GW ~ /- 0.5 ms
This is the delay at the source, still correct on the Earth if ne is massless.
If ne is massive -> additional delay due to propagation:
Current upper limits on ne mass:

6. Strategy Neutrino flash detected by n-detector on Earth
Expected delay between GW and n (GW arrive first):
Syst Stat.
(Very conservative)
Look for GW only into a small window around the neutrino event.
Allow for decreasing search threshold inside such a small window
Choice of the coincidence window ?
Dt ~10 ms aggressive choice !
Dt ~50 ms safer choice !
Let’s go with Dt ~50 ms.
Set the False Alarm probability to ~1% inside the time window.
This sets the FAR to be ~0.2 Hz.
Tune the pipeline threshold accordingly

7. H2 detection range HW injection of SN signal in LIGO:
Waveform: ZM A3B3G1
Pipeline: KW
FAR: 0.2 Hz
H2 90% efficiency for hrss ~7x10-22 Hz-1/2.
This converts to a distance d90 ~ 7 kpc

8. Extrapolation to GEO Ratio H2/GEO sensitivities ~ 8 @ 300Hz.
ZM a3b3g1 spectrum
h(f) (Hz-1)
~300 Hz
freq. (Hz)
Ratio H2/GEO sensitivities ~ 8 @ 300Hz.
Assuming same glitchiness for GEO as for H2,
d90 ~ 0.9 kpc
Optimistic range since glitchiness of H2 seems better than GEO’s
Slightly improved if shift towards higher frequencies …

9. Conclusion Scenario of SN search triggered by a neutrino flash.
Coincidence with neutrino allows for a low threshold in a small coincidence window
(few 10s of ms)
H2 detection range ~ 7 kpc for ZM signal a3b3g1.
GEO detection range < 1 kpc for the same signal.
(Virgo [may 2007] similar to H2 and L1/H1 should cover the entire Galaxy).
Issues:
+ beam pattern effect
More efficient pipeline ?
More recent waveform (Dimmelmeir, Ott et al., higher frequencies …) ?