Search for neutrino emission from the Fermi Bubbles with the ANTARES telescope

Vladimir Kulikovskiy

Overview

• Last updates of the analysis– sparking events cut– energy shift of the MC– limits calculation

• Short overview of analysis

Sparking events cut

• Two possibilities were studied– EventDisplay-like cut “tχ2 < bχ2”– Cut on the distance to the OMs

• 3/10 events with the highest EANN (5.3, 4.6, 4.6) are identified as Bright Point events on event display

• EventDisplay has a selection tχ2 < bχ2 to decide which fit to show

• Additional tχ2 < bχ2 reduces the data, while MC stays on the same level -> the data/MC comparison improves.

• This means that cut is efficient against events which are not present in the MC.

• sparking run 38347• Bbbfit bright point (standalone)

• Seatray production• Distance to the closest OM• Black – events in the sparking spot• Blue – outside.

• density of the events from the distance to the closest OM for the events inside the spot.

Conclusion 1

• tχ2 < bχ2 is efficient against sparking events• distance to the OM cut is interesting, but

more study is needed.

• reconstructed energy of the MC events seems to be lower than of the data events• in log scale it may be interpreted as a shift• The reason may be overestimated water properties. An absorption length increase from 55 to

63 m produces a shift of logE=0.2The proper tests was done by Dimitris in his thesis work. • MC1: ang. acc. dic08 and a maximum

absorption length of 55 m at 470 nm. • MC2: ang. acc. jun09 and scaled

absorption length with a maximum of 63m at 470nm.

• MC was scaled by 23% (obtained by λ distribution fit)• shift was fitted with a chi2 and Kolmogorov-Smirnov test by

shifting on a bin size (logE=0.03)• The best shift obtained was logE=0.1 by both fits• Kolmogorov-Smirnov probability is 0.3 after the scale and shift

MRF optimization

Limits calculation

• Black - Bayesian approach (Nbg = 33)

• Red - Feldman & Cousins approach with b = 11

• Blue - Conrad's approach with b = 11±2

Limits calculatedas a flux for 100 TeV cut • without 30% systematics (black) • including it (red).

Short overview of the analysis• 12 line data 2008-2011• prod 2012-04 and MC v2+v2.2• runs

– QB≥1– no SCAN no sparking runs– good data/MC ratio

• precut– λ>-6– β<1o

– nhits>10– up-going– tχ2 < bχ2

• Difference between number of events in the zones study – 1% syst. error.• Data/MC comparison:

– Scale of MC (atmospheric nu,mu)– Energy shift of MC (atmospheric nu,mu,signal)

• Limits calculations using the Bayesian approach (check with F&C, Conrad)

Summary

• Study of the weak points of the first analysis was done.

• Questions from referees were answered (some of them are reported on the wiki).

• An analysis note is written and distributed 5 days before today.

• Wiki page with a lot of supporting information is written.