Search for point sources with first year of IC86 data

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Introduction

IceCube performed a search for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86-string detector, taken between May 2011 and May 2012.

The search did not identify a single source, but the sensitivity was significantly improved from both the additional year of data and the introduction of improved reconstructions compared to previous publications. These results included the first all-sky search for extended sources of neutrinos, updated searches for neutrino emission from stacked catalogs of sources, and tests of five new catalogs. In all cases, the data were found to be compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos were reported for the sources considered.

This release includes data from only the first year of data taking with the full IC86 configuration, which consists of 138,322 neutrino candidates with reconstructed incoming directions from anywhere in the sky.

“Searches for Extended and Point-like Neutrino Sources with Four Years of IceCube Data,” IceCube Collaboration: M.G. Aartsen et al. Published in The Astrophysical Journal 796 (2014) 109, doi: 10.1088/0004-637X/796/2/109

See paper on the IOP site or on arXiv.

Data release

Suggested citation for this dataset:

IceCube Collaboration (2016): Search for point sources with first year of IC86 data. IceCube Neutrino Observatory. Dataset. DOI:10.21234/B4159R

Click here to download (.zip, 1.6MB)

Included in the download are the following files:

Data files

  • downgoing_events.txt and upgoing_events.txt – Included in these files are all 138,322 neutrino candidate events. The first column is the day in which the event was observed in modified Julian date. The second column gives the energy proxy, which roughly scales as the log10 of the energy deposit seen in the detector. Although the statistical distribution of this parameter matches what is expected from simulations, for individual events, this energy proxy has large errors that were not studied for the purpose of this analysis (see Discussion of the data set below). The next column is the estimated angular error of each event in degrees. The last two columns are the reconstructed event direction in right ascension and declination, given in degrees and obtained using the J2000 reference frame.

Monte Carlo files

  • TabulatedAeff.pdf– Neutrino effective area of this analysis in zenith and energy (Fig. 2 left in paper, in finer binning)
  • TabulatedAeff.txt– Tabulated numbers of tabulatedaeff.pdf
  • AngRes.pdf– Solid line corresponds to median angular resolution of E-2 scaled signal events (Fig. 1 in the paper)
  • AngRes.txt– Tabulated numbers of AngRes.eps

Discussion of the data set

This data sample should be used for the purpose of point source searches. It differs from a previous release of astrophysical neutrinos from the Northern Hemisphere. This data set includes both Northern and Southern Hemispheres, and has a looser event selection since atmospheric muon and neutrino backgrounds are expected to be relatively isotropic. Therefore, the statistical benefits gained by including more events outweigh the inclusion of more background. This data sample should not be used for a diffuse spectral analysis. The energy proxy is not studied in detail—the error for individual events was not estimated—and is only provided to be able to sort events by order of magnitude interest. The total data rate is statistically compatible with all events being of atmospheric neutrino (muon) origin in the northern (southern) atmosphere.

A note on time precision:
The observed times of events in the data files are the modified Julian date at UTC. At the conclusion of the last internal time-dependent analysis, more precise times will be released. This is expected to occur in early 2017.

For any questions about this data release, please write to data@icecube.wisc.edu.