30 research outputs found
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 , a luminosity , a bulk Lorentz
factor . The mean magnetic field 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&
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 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 vertical
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
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 ()
in the Earth's core. We consider a scenario of long-lived ( s), super heavy ( GeV) dark matter that decays
via or . 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
combined with the partial decay width in
the range of s. For , GeV and GeV, the range of constraints is
s.Comment: 9 pages, 9 figure
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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 (Ï) in the Earth's core. We consider a scenario of long-lived , superheavy dark matter that decays via or . 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 Ï”Ï combined with the partial decay width in the range of . For , and , the range of constraints is
Neutrino propagation in the Earth and emerging charged leptons with
Ultra-high-energy neutrinos serve as messengers of some of the highest energy
astrophysical environments. Given that neutrinos are neutral and only interact
via weak interactions, neutrinos can emerge from sources, traverse astronomical
distances, and point back to their origins. Their weak interactions require
large target volumes for neutrino detection. Using the Earth as a neutrino
converter, terrestrial, sub-orbital, and satellite-based instruments are able
to detect signals of neutrino-induced extensive air showers. In this paper, we
describe the software code that simulates tau neutrino and
muon neutrino interactions in the Earth and predicts the spectrum of the
-lepton and muons that emerge. The outputs are lookup
tables of charged lepton exit probabilities and energies that can be used
directly or as inputs to the code designed to simulate
optical and radio signals from extensive air showers induced by the emerging
charged leptons. We describe the inputs to the code, demonstrate its
flexibility and show selected results for -lepton and muon exit
probabilities and energy distributions. The code is open
source, available on github.Comment: 42 pages, 21 figures, code available at
https://github.com/NuSpaceSim/nupypro
A la poursuite des accĂ©lĂ©rateurs cosmiques, Ă lâaide des particules de haute Ă©nergie
The advent of time-domain and multimessenger astronomy opens new perspectives to study the most energetic phenomena of our universe, and understand the mysterious origins of ultra-high-energy cosmic rays (UHECR) and high-energy (HE) neutrinos. Cosmic rays appear as key players in the production of non-thermal and, more generally, multimessenger emissions. In this thesis, we develop several analytical and numerical tools to study the acceleration and interactions of cosmic rays in the vicinity of energetic sources. As HE neutrinos are clear signatures of these processes, we study the detectability of HE neutrino flares from transient sources. We identify two interesting categories of sources, namely pulsars and tidal disruption events. We show with particle-in-cell simulations that pulsars can accelerate high-energy cosmic rays. We demonstrate that a population of millisecond pulsars located in the Galactic bulge can explain the diâ”use gamma-ray emission observed by the HESS detector. Moreover, an extragalactic population of tidal disruptions by massive black holes powering relativistic jets can reproduce the spectrum and composition of UHECRs measured by the Auger experiment, but cannot produce the HE neutrinos detected by the IceCube experiment. Finally, we participate to the development of novel techniques that aim at detecting and reconstructing the properties of very-high-energy (VHE) neutrinos and UHECRs, in the context of the POEMMA and GRAND projects.Ă lâĂšre de lâastronomie des messagers multiples et des phĂ©nomĂšnes transitoires, des perspectives nouvelles sâouvrent pour lâĂ©tude des phĂ©nomĂšnes les plus Ă©nergĂ©tiques de notre univers, et pour dĂ©voiler lâorigine mystĂ©rieuse des rayons cosmiques dâultra-haute Ă©nergie (RCUHE) et des neutrinos de haute Ă©nergie (HE). Les rayons cosmiques sont des particules clĂ©s dans la production de rayonnement non thermique et, plus gĂ©nĂ©ralement, dâĂ©missions multi-messagers. Dans cette thĂšse, nous dĂ©veloppons plusieurs outils analytiques et numĂ©riques pour Ă©tudier lâaccĂ©lĂ©ration et les interactions des rayons cosmiques au sein des sources Ă©nergĂ©tiques. Les neutrinos HE attestant que de tels phĂ©nomĂšnes sont Ă lâĆuvre, nous Ă©tudions le caractĂšre dĂ©tectable de sursauts de neutrinos provenant de sources Ă©phĂ©mĂšres. Nous identifions alors deux catĂ©gories de sources intĂ©ressantes, les pulsars et les Ă©vĂ©nements de rupture par effet de marĂ©e. Nous montrons, avec des simulations particulaires, que les pulsars peuvent accĂ©lĂ©rer des rayons cosmiques. Nous dĂ©montrons quâune population de pulsars milli-secondes situĂ©s au centre de notre Galaxie peut expliquer lâĂ©mission diffuse en rayons gamma observĂ©e par le dĂ©tecteur HESS. De plus, une population extragalactique dâĂ©vĂ©nements de rupture par effet de marĂ©e produisant des jets relativistes peut expliquer le spectre et la composition des RCUHE mesurĂ©es par lâexpĂ©rience Auger, mais ne peut pas produire les neutrinos HE dĂ©tectĂ©s pas lâexpĂ©rience IceCube. Enfin, nous participons au dĂ©veloppement de techniques nouvelles visant Ă dĂ©tecter et reconstruire les propriĂ©tĂ©s des neutrinos de trĂšs haute Ă©nergie et des RCUHE, dans le cadre des projets POEMMA et GRAND
Can we observe neutrino flares in coincidence with explosive transients?
International audienceThe new generation of powerful instruments is reaching sensitivities and temporal resolutions that will allow multi-messenger astronomy of explosive transient phenomena, with high-energy neutrinos as a central figure. We derive general criteria for the detectability of neutrinos from powerful transient sources for given instrument sensitivities. In practice, we provide the minimum photon flux necessary for neutrino detection based on two main observables: the bolometric luminosity and the time variability of the emission. This limit can be compared to the observations in specified wavelengths in order to target the most promising sources for follow-ups. Our criteria can also help distinguishing false associations of neutrino events with a flaring source. We find that relativistic transient sources such as high- and low-luminosity gamma-ray bursts (GRBs), blazar flares, tidal disruption events, and magnetar flares could be observed with IceCube, as they have a good chance to occur within a detectable distance. Of the nonrelativistic transient sources, only luminous supernovae appear as promising candidates. We caution that our criterion should not be directly applied to low-luminosity GRBs and type Ibc supernovae, as these objects could have hosted a choked GRB, leading to neutrino emission without a relevant counterpart radiation. We treat a set of concrete examples and show that several transients, some of which are being monitored by IceCube, are far from meeting the criterion for detectability (e.g., Crab flares or Swift J1644+57). Key words: astroparticle physics / neutrinos / gamma-ray burst: general / BL Lacertae objects: general / pulsars: general / supernovae: genera
Proton acceleration in pulsar magnetospheres
International audiencePulsars have been identified as good candidates for the acceleration of cosmic rays, up to ultra-high energies. However, a precise description of the acceleration processes at play is still to be established. Using 2D particle-in-cell simulations, we study proton acceleration in axisymmetric pulsar magnetospheres. Protons and electrons are extracted from the neutron star surface by the strong electric field induced by the rotation of the star, and electrons and positrons are produced in the magnetosphere through pair production process. As pair production has a crucial impact on electromagnetic fields, on gaps and thus on particle acceleration, we study its influence on the maximum energy and luminosity of protons escaping the magnetosphere. Protons are accelerated and escape in all our simulations. However, the acceleration sites are different for the protons and the pairs. As shown in previous studies, pairs are accelerated to their highest energies at the Y-point and in the equatorial current sheet, where magnetic reconnection plays an important role. In contrast, protons gain most of their kinetic energy below the light-cylinder radius within the separatrix current layers, but they are not confined within the equatorial current sheet. Their maximum Lorentz factors can reach 15% to 75% of the maximum Lorentz factor obtained by acceleration through the full vacuum potential drop from pole to equator, and increase with decreasing pair production. Their luminosity can reach 0.2% to 4% of the theoretical spin down luminosity of an aligned pulsar, and the minimum luminosity is obtained at the transition between the force-free and electrosphere regimes. These estimates support that millisecond pulsars could accelerate cosmic rays up to PeV energies and that new born millisecond pulsars could accelerate cosmic rays up to ultra-high energies.Key words: pulsars: general / acceleration of particles / methods: numerica
High-energy neutrino transients and the future of multi-messenger astronomy
International audienceThe recent discovery of high-energy astrophysical neutrinos and first hints of coincident electromagnetic and neutrino emission herald the beginning of the era of multi-messenger astronomy. Due to their high power, transient sources are expected to supply a significant fraction of the observed energetic astroparticles, through enhanced particle acceleration and interactions. Here, we review theoretical expectations of neutrino emission from transient astrophysical sources and the current and upcoming experimental landscape, highlighting the most promising channels for discovery and specifying their detectability