Characterization of the astrophysical diffuse neutrino flux using starting track events in IceCube
(2024) Physical review D — Vol. 110 (2024)
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- Authors
Lamoureux, Mathieu 
- et. al.
- Abstract
- A measurement of the diffuse astrophysical neutrino spectrum is presented using IceCube data collected from 2011–2022 (10.3 years). We developed novel detection techniques to search for events with a contained vertex and exiting track induced by muon neutrinos undergoing a charged-current interaction. Searching for these starting track events allows us to not only more effectively reject atmospheric muons but also atmospheric neutrino backgrounds in the southern sky, opening a new window to the sub-100 TeV astrophysical neutrino sky. The event selection is constructed using a dynamic starting track veto and machine learning algorithms. We use this data to measure the astrophysical diffuse flux as a single power law flux (SPL) with a best-fit spectral index of <math display="inline"><mi>γ</mi><mo>=</mo><mn>2.5</mn><msubsup><mn>8</mn><mrow><mo>-</mo><mn>0.09</mn></mrow><mrow><mo>+</mo><mn>0.10</mn></mrow></msubsup></math> and per-flavor normalization of <math display="inline"><mrow><msubsup><mrow><mi>ϕ</mi></mrow><mrow><mi>per</mi><mo>-</mo><mtext>flavor</mtext></mrow><mrow><mtext>Astro</mtext></mrow></msubsup><mo>=</mo><mn>1.6</mn><msubsup><mrow><mn>8</mn></mrow><mrow><mo>-</mo><mn>0.22</mn></mrow><mrow><mo>+</mo><mn>0.19</mn></mrow></msubsup><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>-</mo><mn>18</mn></mrow></msup><mo>×</mo><msup><mrow><mi>GeV</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mo>-</mo><mn>2</mn></mrow></msup><mtext> </mtext><msup><mrow><mi mathvariant="normal">s</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup><mtext> </mtext><msup><mrow><mi>sr</mi></mrow><mrow><mo>-</mo><mn>1</mn></mrow></msup></mrow></math> (at 100 TeV). The sensitive energy range for this dataset is 3–550 TeV under the SPL assumption. This data was also used to measure the flux under a broken power law, however we did not find any evidence of a low energy cutoff.
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Citations
de Wasseige, G., Genton, E., Kruiswijk, K., Lamoureux, M., Lazar, J., Raab, C., Myhr, P., Vereecken, M., IceCube, & et al. (2024). Characterization of the astrophysical diffuse neutrino flux using starting track events in IceCube. Physical review D, 110. https://doi.org/10.1103/PhysRevD.110.022001 (Original work published 2024)