Supernova Analysis

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We summarize here the analyses of HitSpool data related to supernova candidate triggers. We furthermore show the 2 ms fast analysis data stream of SNDAQ.

Supernova Hitspool Data Sets

The displayed significance values ξ are calculated from hitspool data after subtreshold muon correction using the entire available data range [-30s, +90s] around the trigger time. The size of the data point indicates the binning size in which the candidate triggered (small = 500ms, middle = 1.5 s , large = 4.0 s) .

Entire list of completely processed datasets

Motivation

By identifying all hits possibly caused by atmospheric muons (triggering ones and sub-threshold) and also cutting out the correlated (bursty) noise hits, we retrieve a data set of hits that represents the Poissonian part of the noise in the detector. This is the basis for a corrected significance statement for any supernova candidate trigger as well as a chance to improve our supernova detection capabilities beyond the Milky Way.

Processing Chain

The diagram illustrates the processing steps involved to derive the subthreshold muon hit identification in hitspool data.

HitSpool Data Groups for Supernova

In summary, we have four levels of hit identification starting at considering all possible hits up to hits cleaned from triggering and subtrigger muons. In order to account for the bursty noise in IceCube we add a non paralyzing deadtime to all hits just as done in SNDAQ.

The hits that survive all of the below mentioned criteria are considered to be our noise hits sample that we investigate. The idea is that the supernova signal will present itself via an enhancement of that noise rate. By subtracting all possible atmospheric background hits due to muons we hope to improve / reduce the false positive alerts and to detect even at lower significances.

Significance Calculation

Performed on a sliding time window as done in the online sndaq analysis. Since in hitspool data we usually have only [-30s,+60s] around the trigger time recorded, we perform two significance calculations: once considering a symmetrical time-window [-30s,+30s] and once the full data range i.e. an asymmetrical time-window [-30s,+60s]. Both analyses are done with all four data types (see above) but only in the binsize in which the original sndaq scaler online analys triggered.

Fast Flux Analysis

The Supernova flux parameterization by Pagliaroli et al (here and here) is a minimum multi-parameter model than can be fit to the lightcurve in order to obtain valuable insight in the underlying process such a signal onset time, the rise-time τ_r, the accreting tie constant τ_a and cooling time constant τ_c

Since the parameterization mentioned above is not needed in order to determine the signal onset and the rise-time τ;_r, we fit a simplier expression to the rising edge of the signal, following the model of Halzen & Raffelt for the signal onset (read more here)

Here is a test page

Lightcurves

Lightcurves are produced from all 4 data gorps mentioned above each in 6 panel plots representing the 6 binnings in which the data is grouped: 1 ms, 2ms, 500ms, 1.5s 4 s and 10 second wide bins. The bin size in which the candidate triggered SNDAQ is underlayed in red.

Hit Maps

The inice detector (without deepcore string) grouped in sets of 100 DOMs with binsize of 500 ms displayed in a sequence to illustrate the local hits distribution during the given time window. All hits refers to all hitspool hits whereas cleaned hits are thos hits surviving deadtime, trigger correction and subtrigger subtraction.

Supernova SNDAQ 2ms Data Sets

The SNDAQ 2 ms datastream is transfered North for supernova candidate triggers with ξ orig > 7.30 or orig > 4.00 and corr > 7.30

Lightcurves for these alerts will also be resented here. If a HitSpool data sets is available for the snalarm as well, we provide both on the same page for convenience.

HESE Data Sets

Motivation

In hadronic cascades - in contrast to electromagnetic showers - a multitude of neutrons is produced. These neutrons subsequently scatter down to thermal energies and can get captured by hydrogen atoms in the ice. The disexcitation of hydrogen leads to a delayed photon signal which follows an exponential decay with a decay time of approximately 200 microseconds. Taking Hitsspool data around every HESE event will allow us to record the delayed signal and thus provide the possibility to determine the hadronic and electromagnetic fraction of cascade events. Based on this, e.g. interaction types can be distinguished and energy reconstruction can be refined.

Solar Flares Data Sets

Motivation

A neutrino signal is expected to arise from hadron acceleration in solar flares. These flare neutrinos would confirm the hadronic nature of solar flares. In combination with photons this process would give insight into the acceleration mechanism(s). Neutrino observatories could help to constrain current parameters in solar flare physics..

HitSpool Monitoring