Interpretation of astrophysical neutrinos observed by IceCube experiment by setting Galactic and extra-Galactic spectral components

Marinelli, A.; Gaggero, Daniele; Grasso, Dario; Urbano, Alfredo; Valli, Mauro

doi:10.1051/epjconf/201611604009

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…An alternative method to scans is to use information about the shape of the Galaxy and information about specific Galactic sources to avoid penalty factors. Some approaches have been to consider contributions from Galactic cosmic rays, constraints from gamma rays measured by Fermi, neutrinos from the Galactic center, various Galactic catalogs such as pulsars, pulsar wind nebulae, supernova remnants, decay/absorption from the dark matter JCAP08(2017)033 halo, the Cygnus-X region, bright nearby stars, and even exoplanets [8,12,13,20,22,[26][27][28][29][30][31][32][33]. In all cases it was found that a single Galactic component cannot explain the entirety of the astrophysical flux.…”

Section: Jcap08(2017)033mentioning

confidence: 99%

The galactic contribution to IceCube's astrophysical neutrino flux

Denton

Marfatia

Weiler

2017

J. Cosmol. Astropart. Phys.

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Abstract. High energy neutrinos have been detected by IceCube, but their origin remains a mystery. Determining the sources of this flux is a crucial first step towards multi-messenger studies. In this work we systematically compare two classes of sources with the data: Galactic and extragalactic. We assume that the neutrino sources are distributed according to a class of Galactic models. We build a likelihood function on an event by event basis including energy, event topology, absorption, and direction information. We present the probability that each high energy event with deposited energy E dep > 60 TeV in the HESE sample is Galactic, extragalactic, or background. For Galactic models considered the Galactic fraction of the astrophysical flux has a best fit value of 1.3% and is < 9.5% at 90% CL. A zero Galactic flux is allowed at < 1σ.

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Section: Jcap08(2017)033mentioning

confidence: 99%

The galactic contribution to IceCube's astrophysical neutrino flux

Denton

Marfatia

Weiler

2017

J. Cosmol. Astropart. Phys.

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“…Another one comes from the position of the Milky Way. As its central region is at negative declinations, the sum of a Galactic and an extragalactic component [20,21] can result in different spectral behaviours in the two hemispheres. From a statistical point of view, 50% of the observed IceCube cosmic neutrino signal events are compatible with a Galactic plane origin [22].…”

Section: Introductionmentioning

confidence: 99%

New constraints on all flavor Galactic diffuse neutrino emission with the ANTARES telescope

Albert¹,

André²,

Anghinolfi³

et al. 2017

Phys. Rev. D

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The flux of very high-energy neutrinos produced in our Galaxy by the interaction of accelerated cosmic rays with the interstellar medium is not yet determined. The characterization of this flux will shed light on Galactic accelerator features, gas distribution morphology and Galactic cosmic ray transport. The central Galactic plane can be the site of an enhanced neutrino production, thus leading to anisotropies in the extraterrestrial neutrino signal as measured by the IceCube Collaboration. The ANTARES neutrino telescope, located in the Mediterranean Sea, offers a favorable view of this part of the sky, thereby allowing for a contribution to the determination of this flux. The expected diffuse Galactic neutrino emission can be obtained, linking a model of generation and propagation of cosmic rays with the morphology of the gas distribution in the Milky Way. In this paper, the so-called “gamma model” introduced recently to explain the high-energy gamma-ray diffuse Galactic emission is assumed as reference. The neutrino flux predicted by the “gamma model” depends on the assumed primary cosmic ray spectrum cutoff. Considering a radially dependent diffusion coefficient, this proposed scenario is able to account for the local cosmic ray measurements, as well as for the Galactic gamma-ray observations. Nine years of ANTARES data are used in this work to search for a possible Galactic contribution according to this scenario. All flavor neutrino interactions are considered. No excess of events is observed, and an upper limit is set on the neutrino flux of 1.1 (1.2) times the prediction of the “gamma model,” assuming the primary cosmic ray spectrum cutoff at 5 (50) PeV. This limit excludes the diffuse Galactic neutrino emission as the major cause of the “spectral anomaly” between the two hemispheres measured by IceCube.Postprint (author's final draft

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“…These issues have led us to question the single power-law hypothesis (1.1) and instead entertain the possibility of a break in the neutrino spectrum [32][33][34][35][36][37][38][39], analogous to (and may be corresponding to [39][40][41][42][43]) the break in the CR spectrum [44]. A two-component flux can arise either from (a) purely astrophysical sources, such as one galactic and one extragalactic component [12,33,39,45,46], or (b) due to a some beyond Standard Model (SM) contribution to the astrophysical neutrino flux, e.g. from heavy dark matter (DM) decay [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63].…”

Section: Introductionmentioning

confidence: 99%

A combined astrophysical and dark matter interpretation of the IceCube HESE and throughgoing muon events

Sui¹,

Dev²

2018

J. Cosmol. Astropart. Phys.

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We perform a combined likelihood analysis for the IceCube 6-year high-energy starting events (HESE) above 60 TeV and 8-year throughgoing muon events above 10 TeV using a two-component neutrino flux model. The two-component flux can be motivated either from purely astrophysical sources or due to a beyond Standard Model contribution, such as decaying heavy dark matter. As for the astrophysical neutrinos, we consider two different source flavor compositions corresponding to the standard pion decay and muon-damped pion decay sources. We find that the latter is slightly preferred over the former as the high-energy component, while the low-energy component does not show any such preference. We also take into account the multi-messenger gamma-ray constraints and find that our two-component fit is compatible with these constraints, whereas the single-component power-law bestfit to the HESE data is ruled out. The astrophysical plus dark matter interpretation of the twocomponent flux is found to be mildly preferred by the current data and the gamma-ray constraints over the purely astrophysical explanation.

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Interpretation of astrophysical neutrinos observed by IceCube experiment by setting Galactic and extra-Galactic spectral components

Cited by 7 publications

References 19 publications

The galactic contribution to IceCube's astrophysical neutrino flux

The galactic contribution to IceCube's astrophysical neutrino flux

New constraints on all flavor Galactic diffuse neutrino emission with the ANTARES telescope

A combined astrophysical and dark matter interpretation of the IceCube HESE and throughgoing muon events

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