Prospects of neutrino observations of the Central Molecular Zone and Cygnus OB2 with KM3NeT/ARCA

Prospects of neutrino observations of the Central Molecular Zone and Cygnus OB2 with KM3NeT/ARCA Marouane Benhassi*, Riccardo M. Bozza, Aart Heijboer, Walid Idrissi Ibnsalih, Antonio Ambrosone, Antonio Marinelli, Pasquale Migliozzi on behalf of KM3NeT Collaboration XXI International Workshop on Neutrino Telescopes September 29, 2025 to October 3, 2025 * Department of Mathematics and Physics of the University of Campania Luigi Vanvitelli - Italy * INFN - sezione di Napoli Outline ● KM3NeT experiment ● Galactic extended sources: Central Molecular Zone and Cygnus OB2 ● Unblinded results ● Source map smearing technique Marouane Benhassi [email protected] 2 KM3NeT experiment KM3NeT experiment ARCA: ● Main goal: High energy astrophysics; ● TeV-PeV energy range; ● 230 strings (115 for each block); ● 18 Digital Optical Modules (DOMs) per string with 36 m vertical spacing; ● Depth ~3500 m, about 100 km off-shore the small town of Portopalo di Passero on Sicily, Italy. ORCA: ● Main goal: Neutrino oscillations; ● 1-100 GeV energy range; ● 115 strings; ● 18 DOMs per string with 9 m vertical spacing ; ● Depth ~2500 m about 40 km off-shore Toulon, France. Both detectors share same technology. Marouane Benhassi [email protected] 4 KM3NeT experiment Detection principle Cherenkov light induced by the relativistic particle resulting from the interaction of an incoming neutrino with water medium. Although the detectors are under construction, KM3NeT is already taking data. This analysis uses ARCA6-21 data, representing the data collected by ARCA6, ARCA8, ARCA19, and ARCA21 setups, accounting for a total lifetime of 640 days. For the expectations with the completed detector, ARCA230, Monte Carlo (MC) simulation is used corresponding to a lifetime of 10 years. Marouane Benhassi [email protected] 5 Galactic extended sources: Central Molecular Zone and Cygnus OB2 Galactic extended neutrino sources emission Galactic extended neutrino sources are astrophysical sources within our Galaxy which have an angular size from hundred of parsecs up to kiloparsec depending on their position on the sky. We are particularly interested in those made by clouds of molecular gas, which eventually have a nearby candidate accelerator. Neutrinos are produced through the interaction of relativistic protons from the cosmic rays and the molecular gas. CRs Neutrinos Marouane Benhassi [email protected] 7 Central Molecular Zone: Motivations The Central Molecular Zone (CMZ): ● is a region of few hundred parsecs in the center of our Galaxy with an angular extensions |l|<1° and |b|<0.3° ; ● has an estimated gas density two orders of magnitude larger than the gas density in the galaxy; ● contains some of the most massive Galactic molecular clouds such as Sgr A, Sgr B, and Sgr C. Marouane Benhassi [email protected] 8 Central Molecular Zone: Motivations CMZ location with respect to the KM3NeT detector visibility, its gas distribution, and the mechanism of neutrino production. HAWC hadro-nuclear interactions https://arxiv.org/pdf/2407.03682 Marouane Benhassi [email protected] 9 Analysis method Method: The test statistic is given by: The likelihood can be written as: Where 𝜇 is the signal strength and ˆ𝜇 is the value that maximizes the 𝑙𝑜𝑔𝐿. Si and Bi represent the signal and the background PDFs. Sensitivity is defined as: Median upper limit of the signal strength Neutrino flux Marouane Benhassi [email protected] 16 Central Molecular Zone: Sensitivity of KM3NeT/ARCA The sensitivities of ARCA6-21 and ARCA230 are shown. A gaussian smearing was used to take into account the extension of this source with a σ = 0.6°. We used track like events and all flavours with 0.5 PeV as neutrino cut-off. Marouane Benhassi [email protected] 17 Cygnus OB2: Sensitivity of KM3NeT/ARCA The sensitivities of ARCA6-21 and ARCA230 are shown. A gaussian smearing was used to take into account the extension of this source with a σ = 0.7°. We used track like events and all flavours. In future, we will combine track and shower events, which will be crucial for studying this source. Marouane Benhassi [email protected] 18 Source map smearing results: CMZ as an example Source-map smearing: CMZ as an example Left: CMZ map extracted from HAWC paper. Right: smearing of the CMZ map. The smearing is based on an intensity map Marouane Benhassi [email protected] 20 Smearing New detector Point Spread Function (PSF) Left: the new detector PSF based on the source map smearing compared with the gaussian PSF. Right: sensitivity of ARCA6-21 using both source map smearing and gaussian smearing. Due to the CMZ's size, sensitivity improved by less than 1%. Marouane Benhassi [email protected] 21 Conclusions KM3NeT/ARCA is a key experiment to understand the extended and point-like emission from our Galaxy ● No significance has been seen neither from the CMZ nor the Cygnus OB2 with ARCA6-21 data. ● Upper limits were set for both CMZ and Cygnus OB2. ● We expect to constrain the neutrino emission predicted for the two sources with the full ARCA230. ● A new realistic smearing technique was developed to study the morphologies of the sources, providing an alternative to the simple Gaussian approximation. Thank you for your attention