Introduction: Muons and Neutrinos from the SGR 1806-20 Dec 27 outburst
The main aim of this
analysis is to use AMANDA-II as a muon
detector. Muons could be produced in the
cascades from charged pions induced by the gammas produced in the extremely intense burst of the magnetar known as SGR 1806-20. The source is located
in AMANDA's upper hemisphere hence the standard muon neutrino channel is not very promising given the small
interaction probability in the atmosphere and the background of atmospheric muons.
The other channel of
interest is the neutrino induced cascade that
will be subject to another unblinding request for the
next future.
Expected event rates are
calculated in a phenomenological model in
F. Halzen, H. Landsman and T. Montaruli,
TEV
PHOTONS AND NEUTRINOS FROM GIANT SOFT-GAMMA REPEATERS FLARES, astro-ph/0503348.
Event rates strongly
depend on the assumed spectral index and on the maximum achievable photon
energies.
These are uncertainties
and arbitrary parameters in the model and the E-1.47
assumption is justified for the initial outburst given previous detailed
observations by Beppo-SAX of a similar burst from SGR1900+14.
More
recently SGR 1806-20 were measured by Konus-Wind
and Helicon, astro-ph/0502541. In the paper the spectrum of the tail of the burst (not the initial spike) is reported
in Fig 2: it exhibits a hard power-law component with E-1.8
up to 104 keV were the instruments
saturate.
Another spectral measurement
was reported by SWIFT, astro-ph/0503030: the
event unfortunately illuminated the detector from behind and the flux passed
through the spacecraft and the shielding. The good time resolution of 0.1 ms allowed the observation of the time structure of the
spike that lasted about 0.5 s. Nonetheless the energy resolution is poor and
the spectral measurement in Fig. 3 up to 10 MeV not
so reliable.
The last bin (1.5-10) MeV may well contain a power-law hard component, though the
authors fit the spectrum with an OTTB function (characteristic of em processes).
Also GEOTAIL published the
counting rate as a function of time that decreases by more than 3 orders of
magnitude in 0.6 s.
The relevant information for
the analysis are:
- coordinates
of the source: we assume the values from P.B. Cameron et al.,
astro-ph/0502428:
RA (J2000) 18h 08m 39.4s = 272.16 deg
DEC (J2000) -20deg24'39.7" = -20.41 deg
- Most of the satellites
report a spike duration of the order of < 0.6 s
- Various satellites report the trigger time,
from which, knowing the position of the satellite we have to calculate the
delay time of photons at Earth (and at AMANDA). See the method here and the
definition of the reference system.
In the table the trigger times and location
of satellites, their time resolution and the estimated time at AMANDA are
given.
|
Satellite and reference |
(X,Y,Z) of satellite (km) |
Time resolution (ms) |
Trigger time (h:m:ss)
and Estimated time at Earth (ss) (delay in ms) |
|
(-1.5997e5,97945,19671) |
5.48 |
21:30:26.35 -> 26.71 (361.884) |
|
|
(-72175.2453,-72233.5599,110158.1196) |
10-50 |
21:30:26.55 -> 26.88 (331.146) |
|
|
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1 |
|
|
|
8000 km from centre of Earth 7000 km Sunward of Earth�s centre |
|
21:30:26.124 -> 26.15 (26.68) 21:30:26.468 -> 26.49 (23.34) |
|
|
We consider this paper unreliable |
Detection of signal reflected by Moon (time not reliable since inconsistent in the paper Delay time 508.6 ms |
256 |
21:30:29.303 inconsistent with Tcoronas
= TWind + 7.69s = 21:30:28.22 by 1 sec 21:30:20.53 -> 25.62 (508.6) |
In summary: the first time at Earth
26.15 s from Cluster 4 and the last is 26.88 s for INTEGRAL so the time
difference between Times at Earth for various satellites is 0.73 s.
If we assume a spike duration of 0.6 s
and that all photons that produce the hard E^-1.47 detectable component are
emitted in the spike, then 0.73+0.6 = 1.33 s
We cannot assume a time window less than
this value and with no loss on the MDF we can safely take a 1.5 s time window
for this analysis.
More details can be found in J. Dumm's talk.
SWIFT

GEOTAIL