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Search for dark matter towards the Galactic Centre with 11 years of ANTARES data

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 Publication date 2019
  fields Physics
and research's language is English




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Neutrino detectors participate in the indirect search for the fundamental constituents of dark matter (DM) in form of weakly interacting massive particles (WIMPs). In WIMP scenarios, candidate DM particles can pair-annihilate into Standard Model products, yielding considerable fluxes of high-energy neutrinos. A detector like ANTARES, located in the Northern Hemisphere, is able to perform a competitive search looking towards the Galactic Centre, where a high density of dark matter is thought to accumulate. Both this directional information and the spectral features of annihilating DM pairs are entered into an unbinned likelihood method to scan the data set in search for DM-like signals in ANTARES data. Results obtained upon unblinding 11 years of data are presented. A non-observation of dark matter is converted into limits on the velocity-averaged cross section for WIMP pair annihilation.



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A search for high-energy neutrinos coming from the direction of the Galactic Centre is performed using the data recorded by the ANTARES neutrino telescope from 2007 to 2012. The event selection criteria are chosen to maximise the sensitivity to possible signals produced by the self-annihilation of weakly interacting massive particles accumulated around the centre of the Milky Way with respect to the atmospheric background. After data unblinding, the number of neutrinos observed in the line of sight of the Galactic Centre is found to be compatible with background expectations. The 90% C.L. upper limits in terms of the neutrino+anti-neutrino flux, $rm Phi_{ u_{mu}+bar{ u}_mu}$, and the velocity averaged annihilation cross-section, $rm <sigma_{A}v>$, are derived for the WIMP self-annihilation channels into $rm bbar{b},W^{+}W^{-},tau^{+}tau^{-},mu^{+}mu^{-}, ubar{ u}$. The ANTARES limits for $rm <sigma_{A}v>$ are shown to be the most stringent for a neutrino telescope over the WIMP masses $rm 25,GeV < M_{WIMP} < 10,TeV$.
We present the results of the first combined dark matter search targeting the Galactic Centre using the ANTARES and IceCube neutrino telescopes. For dark matter particles with masses from 50 to 1000 GeV, the sensitivities on the self-annihilation cross section set by ANTARES and IceCube are comparable, making this mass range particularly interesting for a joint analysis. Dark matter self-annihilation through the $tau^+tau^-$, $mu^+mu^-$, $bbar{b}$ and $W^+W^-$ channels is considered for both the Navarro-Frenk-White and Burkert halo profiles. In the combination of 2,101.6 days of ANTARES data and 1,007 days of IceCube data, no excess over the expected background is observed. Limits on the thermally-averaged dark matter annihilation cross section $langlesigma_Aupsilonrangle$ are set. These limits present an improvement of up to a factor of two in the studied dark matter mass range with respect to the individual limits published by both collaborations. When considering dark matter particles with a mass of 200 GeV annihilating through the $tau^+tau^-$ channel, the value obtained for the limit is $7.44 times 10^{-24} text{cm}^{3}text{s}^{-1}$ for the Navarro-Frenk-White halo profile. For the purpose of this joint analysis, the model parameters and the likelihood are unified, providing a benchmark for forthcoming dark matter searches performed by neutrino telescopes.
The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using $gamma$-ray observations towards the inner 300 parsecs of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant $gamma$-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section $langle sigma vrangle$. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach $langle sigma vrangle$ values of $rm 6times10^{-26} cm^3s^{-1}$ in the $W^+W^-$ channel for a DM particle mass of 1.5 TeV, and $rm 2times10^{-26} cm^3s^{-1}$ in the $tau^+tau^-$ channel for 1 TeV mass. For the first time, ground-based $gamma$-ray observations have reached sufficient sensitivity to probe $langle sigma vrangle$ values expected from the thermal relic density for TeV DM particles.
Using data recorded with the ANTARES telescope from 2007 to 2015, a new search for dark matter annihilation in the Milky Way has been performed. Three halo models and five annihilation channels, $rm WIMP + WIMP to b bar b, W^+ W^-, tau^+ tau^-, mu^{+} mu^{-}$ and $ u bar{ u}$, with WIMP masses ranging from 50 $frac{text{GeV}}{text{c}^2}$ to 100 $frac{text{TeV}}{text{c}^2}$, were considered. No excess over the expected background was found, and limits on the thermally averaged annihilation cross--section were set.
The main goal of the ANTARES neutrino telescope is the identification of neutrinos from cosmic accelerators. The good visibility towards the Southern sky for neutrino energies below 100 TeV and the good angular resolution for reconstructed events make the telescope excellent to test for the presence of point-like sources, especially of Galactic origin. The median angular resolution for track-like events (mainly from $ u_{mu}$ CC interactions) is $0.4^{circ}$ while the median angular resolution for contained shower-like events (mainly from $ u_{e}$ CC and all-flavour NC interactions) is $3^{circ}$. Recently the ANTARES Collaboration published the result of the search for cosmic point-like neutrino sources using track-like and shower-like events collected during nine years of data taking. In this contribution, an update to this analysis using eleven years of data recorded between early 2007 and the end of 2017, for a total livetime of 3136 days, is presented. Moreover, the results of a search for time and space correlation between the ANTARES events and 54 IceCube tracks and those of the searches for neutrino candidates associated with the IceCube-170922A event or from the direction of the TXS 0506+056 blazar are reported.
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