Probing Dark Matter–Neutrino Interactions through High Energy Neutrino Observations from AGN

Probing Dark Matter–Neutrino Interactions through High Energy Neutrino Observations from AGN Khushboo Dixit ([email protected]) with Soebur Razzaque (CAPP, University of Johannesburg) Gopolang Mohlabeng (Simon Fraser University, Canada) XXI Workshop on Neutrino Telescopes, Padua - Italy 2 Oct 2025 2 Dark Matter Rotational curves of galaxies Weak lensing effect in Bullet Clusters Anisotropies in CMB Khushboo Dixit University of Johannesburg Earlier Dark Matter Searches 3 Essig et al., PRL 2012 Khushboo Dixit University of Johannesburg 𝜈-DM interaction: Z’ model interpretation 4 ●A simple particle physics framework is a new 𝑈 1 ′gauge boson (𝑍′) that couples to all lepton flavors and to dark matter χ. ●If DM of mass mχis a complex scalar with coupling 𝑔𝜒, neutrinos couple with 𝑔𝜈, the scattering cross section mediated by 𝑍′has two limits (Cline & Puel, 2023) ●Provides theoretical motivation for studying both (i) energy-independent and (ii) linear energy-dependent ν-DM cross sections in astrophysical analyses. Khushboo Dixit University of Johannesburg Bounds on 𝜈-DM interaction 5 Basic idea: Infer ν-DM scattering properties by studying how the neutrino flux from a source gets attenuated along its journey (Choi et al., PRD 2019) We need: ●High energy neutrino sources, whose neutrinos are already detected ●Theoretical understanding of the initial ν-spectrum at the source ●Knowledge of the possible DM distribution along the path of neutrino journey How can we put model independent bounds on neutrino-dark matter interactions? Khushboo Dixit University of Johannesburg Searches for Point-like Neutrino Sources at IceCube IceCube Collaboration, 2022 6 Credit: IceCube/NASA Khushboo Dixit University of Johannesburg High Energy Astrophysical Neutrino Data from IceCube 7 Point sources detected by IceCube with high significance ➔IceCube has performed several all-sky searches for point-like neutrino sources using track-like events induced by and . ➔PSTracks event selection : IceCube public data from its IC86 configuration ◆Designed for point-source studies with the good angular resolution of tracks ◆Can tolerate larger atmospheric background contributions compared to diffuse neutrino analyses. ➔Cumulative excess of events has been observed, mostly determined by four sources with significance of 3.3𝜎(Abbasi, et al., 2021) Khushboo Dixit University of Johannesburg High Energy Astrophysical Neutrino Data from IceCube Also included NGC 4151, 2.9𝜎significance (Abbasi et al., 2024) 7 Point sources detected by IceCube with high significance ➔IceCube has performed several all-sky searches for point-like neutrino sources using track-like events induced by and . ➔PSTracks event selection : IceCube public data from its IC86 configuration ◆Designed for point-source studies with the good angular resolution of tracks ◆Can tolerate larger atmospheric background contributions compared to diffuse neutrino analyses. ➔Cumulative excess of events has been observed, mostly determined by four sources with significance of 3.3𝜎(Abbasi, et al., 2021) Khushboo Dixit University of Johannesburg Statistical Analysis ●Typical pion-decay neutrino flux from astrophysical sources: ●Events from the source: ●Number of signal events: ●Test statistics (Braun et al. 2008) Likelihood function 8 Table: Best-fit values with corresponding 1σintervals of number of events and the spectral index (K.D., Miranda, Razzaque, 2024) Khushboo Dixit University of Johannesburg Constraint on DM-neutrino Cross-Section 13 K.D., Mohlabeng, Razzaque, in prep. Constant : For benchmark models where = 0 ; NGC 1068 dominates the stacking analysis. for SMBH with lighter mass peaks at smaller distance with higher amplitude, hence larger Khushboo Dixit University of Johannesburg Constraint on DM-neutrino Cross-Section 14 K.D., Mohlabeng, Razzaque, in prep. Constant : For benchmark profiles with ≠ 0, , PKS 1424+240 dominates the stacking analysis. The denser the dark matter spike, the stronger the depletion due to self-annihilations. Khushboo Dixit University of Johannesburg Constraint on DM-neutrino Cross-Section 15 K.D., Mohlabeng, Razzaque, in prep. Energy-dependent : Linear energy dependence, i.e., where, and, Khushboo Dixit University of Johannesburg Constraint on DM-neutrino Cross-Section 16 K.D., Mohlabeng, Razzaque, in prep. Energy-dependent : ❑For BM1-like models (No DM-annihilation): NGC 4151 gives the tightest constraint, due to harder spectrum ❑For BM2-like models : Again, PKS 1424+240 dominates the stacking analysis Khushboo Dixit University of Johannesburg Summary 17 ●Astrophysical neutrinos provide an enormous platform to probe dark matter. ●IceCube has provided its data publicly and allows to put significant constraints on neutrinodark matter interaction ●We obtain bound on the DM-𝜈cross-section from recently observed four neutrino point sources, also provided an overall bound through stacking analysis ○In no DM-annihilation scenarios: tightest constraint from NGC 1068 (lightest SMBH mass) ○For energy dependent DM-𝜈cross section, event distribution also plays important role ○In case of DM-annihilation, tightest constraint from PKS 1424+240 (heaviest SMBH mass) ●Future experiments viz, KM3Net, IceCube Gen-2, P-ONE and so on can improve results in this line. Khushboo Dixit University of Johannesburg Summary 17 Thank you for attention! ●Astrophysical neutrinos provide an enormous platform to probe dark matter. ●IceCube has provided its data publicly and allows to put significant constraints on neutrinodark matter interaction ●We obtain bound on the DM-𝜈cross-section from recently observed four neutrino point sources, also provided an overall bound through stacking analysis ○In no DM-annihilation scenarios: tightest constraint from NGC 1068 (lightest SMBH mass) ○For energy dependent DM-𝜈cross section, event distribution also plays important role ○In case of DM-annihilation, tightest constraint from PKS 1424+240 (heaviest SMBH mass) ●Future experiments viz, KM3Net, IceCube Gen-2, P-ONE and so on can improve results in this line. Khushboo Dixit University of Johannesburg BACKUP: Dark Matter Column Density Profile 18 NGC 1068 K.D., Mohlabeng, Razzaque, in prep. 𝑚ꭓ= 1 𝐺𝑒𝑉 𝑚ꭓ= 0.001 𝑀𝑒𝑉 Khushboo Dixit University of Johannesburg BACKUP: Previous bounds 19 Cline et al., 2023 Khushboo Dixit University of Johannesburg 20 Dark Matter Profile ➢𝑹𝑺Schwarzschild Radius ➢𝟒𝑹𝑺=𝒓𝒊inner radius of spike ➢𝑹𝒆𝒎 Point where neutrino emission is supposed to happen ➢𝒓𝒉=G* 𝑴𝑩𝑯 /𝝈𝟐influence radius of SMBH (within which gravitational effects of the SMBH directly affect the motion of the surrounding stars.) ➢𝑹𝑺𝑷 spike radius ➢𝒓𝑺scale radius Khushboo Dixit University of Johannesburg