Signatures of secondary acceleration in neutrino flares

High-energy neutrino flares are interesting prospective counterparts to photon flares, as their detection would guarantee the presence of accelerated hadrons within a source, provide precious information about cosmic-ray acceleration and interactions, and thus impact the subsequent modeling of non-thermal emissions in explosive transients. In these sources, photomeson production can be efficient, producing a large amount of secondary particles, such as charged pions and muons, that decay and produce high-energy neutrinos. Before their decay, secondary particles can experience energy losses and acceleration, which can impact high-energy neutrino spectra and thus affect their detectability. In this work, we focus on the impact of secondary acceleration. We consider a one zone model, characterized mainly by a variability timescale $t_{\rm var}$, a luminosity $L_{\rm bol}$, a bulk Lorentz factor $\Gamma$. The mean magnetic field $B$ is deduced from these parameters. The photon field is modeled by a broken power-law. This generic model allows to evaluate systematically the maximum energy of high-energy neutrinos in the parameter space of explosive transients, and shows that it could be strongly affected by secondary acceleration for a large number of source categories. In order to determine the impact of secondary acceleration on the high-energy neutrino spectrum and in particular on its peak energy and flux, we complement these estimates by several case studies. We show that secondary acceleration can increase the maximum neutrino flux, and produce a secondary peak at the maximum energy in the case of efficient acceleration. Secondary acceleration could therefore enhance the detectability of very-high-energy neutrinos, that will be the target of next generation neutrino detectors such as KM3NeT, IceCube-Gen2, POEMMA or GRAND.Comment: 12 pages, 4 figues, submitted to A&

Synthetic is all you need: removing the auxiliary data assumption for membership inference attacks against synthetic data

Synthetic data is emerging as the most promising solution to share individual-level data while safeguarding privacy. Membership inference attacks (MIAs), based on shadow modeling, have become the standard to evaluate the privacy of synthetic data. These attacks, however, currently assume the attacker to have access to an auxiliary dataset sampled from a similar distribution as the training dataset. This often is a very strong assumption that would make an attack unlikely to happen in practice. We here show how this assumption can be removed and how MIAs can be performed using only the synthetic data. More specifically, in three different attack scenarios using only synthetic data, our results demonstrate that MIAs are still successful, across two real-world datasets and two synthetic data generators. These results show how the strong hypothesis made when auditing synthetic data releases - access to an auxiliary dataset - can be relaxed to perform an actual attack

Neutrino Target-of-Opportunity Sky Coverage and Scheduler for EUSO-SPB2

Very-high-energy neutrinos can be observed by detecting air shower signals. Detection of transient target of opportunity (ToO) neutrino sources is part of a broader multimessenger program. The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) Mission, launched on May 12, 2023, was equipped with an optical Cherenkov Telescope (CT) designed to detect up-going air showers sourced by Earth-skimming neutrinos that interact near the Earth's limb. Presented here is an overview of the sky coverage and ToO scheduler software for EUSO-SPB2. By using the balloon trajectory coordinates and setting constraints on the positions of the Sun and Moon to ensure dark skies, we can determine if and when a source direction is slightly below the Earth's limb. From a source catalog, CT scheduling and pointing is performed to optimize the search for high-energy neutrinos coming from astrophysical sources. Some sample results for EUSO-SPB2 are shown.Comment: 10 pages, 6 figures, ICRC2023 Conference Proceeding

Overview of the EUSO-SPB2 Target of Opportunity program using the Cherenkov Telescope

During the Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) mission, we planned Target of Opportunity (ToO) operations to follow up on possible sources of $\gtrsim 10 \, {\rm PeV}$ neutrinos. The original plan before flight was to point the onboard Cherenkov Telescope (CT) to catch the source's path on the sky just below Earth's horizon. By using the Earth as a tau-neutrino to tau-lepton converter, the CT would then be able to look for optical extensive air shower signals induced by tau-lepton decays in the atmosphere. The CT had a field of view of $6.4^\circ$ vertical $\times$ $12.8^\circ$ horizontal. Possible neutrino source candidates include gamma ray bursts, tidal disruption events and other bursting or flaring sources. In addition, follow-ups of binary neutron star mergers would have been possible after the start of the O4 observation run from LIGO-Virgo-KAGRA. The resulting exposure is modeled using the NuSpaceSim framework in ToO mode. With the launch of the EUSO-SPB2 payload on the 13th May 2023, this summarizes the ToO program status and preliminary data, as available

Indirect dark matter searches at ultrahigh energy neutrino detectors

High to ultrahigh energy neutrino detectors can uniquely probe the properties of dark matter $$ by searching for the secondary neutrinos produced through annihilation and/or decay processes. We evaluate the sensitivities to dark matter thermally averaged annihilation cross section $⟨⁢⟩$ and partial decay width $Γ_{→\overline{}}⁢$ (in the mass scale $10^7≤_/GeV≤10^{15})$ for next generation observatories like POEMMA (Probe of Extreme Multi-Messenger Astrophysics) and GRAND (Giant Radio Array for Neutrino Detection). We show that in the range $10^7≤/GeV≤10^{11}$, space-based Cherenkov detectors like POEMMA have the advantage of full-sky coverage and rapid slewing, enabling an optimized dark matter observation strategy focusing on the Galactic Center. We also show that ground-based radio detectors such as GRAND can achieve high sensitivities and high duty cycles in radio quiet areas. We compare the sensitivities of next generation neutrino experiments with existing constraints from IceCube and updated 90% C.L. upper limits on $⟨⁢⟩$ and $Γ_{→⁢\overline{}}$ using results from the Pierre Auger Collaboration and Antarctic Impulsive Transient Antenna. We show that in the range $10^7≤_/GeV≤10^{11}$, POEMMA and GRAND10k will improve the neutrino sensitivity to particle dark matter by factors of 2 to 10 over existing limits, whereas GRAND200k will improve this sensitivity by 2 orders of magnitude. In the range $10^{11}≤/GeV≤10^{15}$, POEMMA’s fluorescence observation mode will achieve an unprecedented sensitivity to dark matter properties. Finally, we highlight the importance of the uncertainties related to the dark matter distribution in the galactic halo, using the latest fit and estimates of the galactic parameters

Neutrino constraints on long-lived heavy dark sector particle decays in the Earth

Recent theoretical work has explored dark matter accumulation in the Earth and its drift towards the center of the Earth that, for the current age of the Earth, does not necessarily result in a concentration of dark matter ($\chi$) in the Earth's core. We consider a scenario of long-lived ($\tau_\chi\sim 10^{28}$ s), super heavy ($m_\chi=10^7-10^{10}$ GeV) dark matter that decays via $\chi\to \nu_\tau H$ or $\chi\to \nu_\mu H$. We show that an IceCube-like detector over 10 years can constrain a dark matter density that mirrors the Earth's density or has a uniform density with density fraction $\epsilon_\rho$ combined with the partial decay width $B_{\chi\to \nu_\tau H}\Gamma_\chi$ in the range of $(\epsilon_\rho/10^{-10}) B_{\chi\to \nu_\tau}\Gamma_\chi \lesssim 3\times 10^{-29}-3\times 10^{-28}$ s$^{-1}$. For $\chi\to \nu_\mu H$, $m_\chi = 10^8-10^{10}$ GeV and $E_\mu>10^7$ GeV, the range of constraints is $(\epsilon_\rho/10^{-10}) B_{\chi\to \nu_\mu}\Gamma_\chi \lesssim 6\times 10^{-29}-1.4\times 10^{-27}$ s$^{-1}$.Comment: 9 pages, 9 figure

Neutrino constraints on long-lived heavy dark sector particle decays in the Earth

Recent theoretical work has explored dark matter accumulation in the Earth and its drift toward the center of the Earth that, for the current age of the Earth, does not necessarily result in a concentration of dark matter (χ) in the Earth's core. We consider a scenario of long-lived $(τ_χ∼10^{28}s)$, superheavy $(m_χ=10^7-10^{10} GeV)$ dark matter that decays via $χ→ν_τ\overline{ν}_τ$ or $χ→ν_μ\overline{ν}_μ$. We show that an IceCube-like detector over 10 years can constrain a dark matter density that mirrors the Earth's density or has a uniform density with density fraction ϵρ combined with the partial decay width $B_{χ→ντ\overline{ν}_τΓ_χ}$ in the range of $(ϵρ/10^{-10})B_{χ→ν_τ}Γ_χ≲1.5×10^{-29}-1.5×10^{-28} s^{-1}$. For $χ→ν_μ\overline{ν}_μ, m_χ=10^8-10^{10} GeV$, and $E_μ>10^7 GeV$, the range of constraints is $(ϵρ/10_{-10})B_{χ→ν_μ}Γ_χ≲3×10^{-29}-7×10^{-28} s^{-1}$

POEMMA: Probe Of Extreme Multi-Messenger Astrophysics

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of UHECRs and CTNs from space will yield orders-of-magnitude increase in statistics of observed UHECRs at the highest energies, and the observation of the cosmogenic flux of neutrinos for a range of UHECR models. These observations should solve the long-standing puzzle of the origin of the highest energy particles ever observed, providing a new window onto the most energetic environments and events in the Universe, while studying particle interactions well beyond accelerator energies. The discovery of CTNs will help solve the puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics with the study of neutrino properties at ultra-high energies.Comment: 8 pages, in the Proceedings of the 35th International Cosmic Ray Conference, ICRC217, Busan, Kore