Cosmic Rays and Neutrinos in the Multi-Messenger Era

9 déc. 2024, 08:00 → 13 déc. 2024, 19:00 Europe/Paris

APC Laboratory (Paris)

The 'Cosmic Rays  in the Multi-Messenger Era' conference aims to bring together the scientific communities working on high-energy cosmic rays, from an experimental point of view as well as from a theoretical and phenomenological sides. In addition to detailed presentations of theoretical models dealing with the production of cosmic rays and secondary neutrinos and gamma-rays, the conference will include reviews of the latest experimental results as well as prospects for the next decade.

Each session will end with general discussion of presented results. Additionally we organize poster session for PhD students and young researchers.

Organizing committee: 

G. de Wasseige, co-chair 
S. Gabici 
M. Kachelriess, co-chair  
A. Kouchner
M. Lemoine 
A. Neronov 
D. Semikoz, chair 
S.Vydelingum, secretary

lun. 9 décembre

08:30 → 09:00 Registration

09:00 → 09:10 Welcome

Orateur: Dmitri SEMIKOZ (APC, Paris)

09:10 → 12:00 UHECRs

09:10 Telescope Array results

Orateur: Yoshiki Tsunesada

09:40 Auger results

Orateur: Ralph Engel

10:10 Coffee

10:30 New developments in EPOS : toward a global approach from Heavy Ions to Cosmic Rays

Orateur: Tanguy Pierog

11:00 QGSJet 3.1

Orateur: Sergey Ostapchenko

11:30 Discussion UHECR

12:00 → 13:30 Lunch

13:30 → 15:30 GMF

13:30 GMF I

Orateur: Prof. JinLin Han

14:00 GMF II

Orateur: Prof. Michael Unger

14:30 GMF III

Orateur: Alexander Korochkin (ULB, Bruxelles)

15:00 Does the Local Bubble bias Galactic magnetic field models used to backtrack UHECRs?

Orateur: Vincent Pelgrims

15:30 → 16:00 Coffee

16:00 → 16:30 GMF2

16:00 Discussion GMF

16:30 → 18:30 POSTER SESSION 1

17:00 Ultra-high-energy cosmic rays from ultra-fast outflows of active galactic nuclei

We investigate ultra-fast outflows (UFOs) of active galactic nuclei (AGN) as potential sites for the production of the highest-energy cosmic rays, focusing on cosmic-ray nuclei, a previously unexplored aspect. These mildly-relativistic large-scale outflows, with velocities reaching up to half the speed of light, are ubiquitous in AGN. We numerically study the processes that affect the maximum energy of the cosmic rays with 3D CRPropa simulations of the vicinity of the AGN. We then apply our method to 87 observed UFOs. We find that the studied UFOs can accelerate iron nuclei to $\sim10^{20}\,$eV, but only a small fraction of these sources allow the nuclei to escape, owing to photonuclear interactions with the intense photon fields within the AGN. The expected flux suppression limits the viability of UFOs as the sources of the observed ultra-high-energy cosmic-ray nuclei, although an intermittent escape during low emissivity states of the associated AGN may be possible. The vast majority of the investigated outflows mainly allows protons and neutrons, which are either primary or byproducts of photodisintegration, to escape due to a lower number of interactions. We conclude that UFOs can supply the protons below the ankle of the cosmic-ray spectrum, making them intriguing source candidates for this component of the observed flux.

Orateur: Domenik Ehlert (Norwegian University of Science and Technology)

17:10 A search for neutron fluxes from Galactic candidate sources using data from the Pierre Auger Observatory

Since neutral particles are not deflected by magnetic fields, they are a valuable tool for studying the sources of ultra-high-energy cosmic rays (UHECRs). It is expected that sources of UHECRs will also produce neutrons through nuclear interactions and photo-pion production near the source. Free neutrons undergo beta decay, traveling a typical distance of $9.2\times(E/1\,\mathrm{EeV})$ kpc. As a result, neutron fluxes in the EeV energy range could potentially be detected from Galactic sources of UHECRs. Using data from the Surface Detector of the Pierre Auger Observatory, the world's largest cosmic ray detector, we search for neutron fluxes from candidate Galactic sources. Since it is not possible to distinguish between air showers caused by protons or neutrons, we would identify neutron fluxes as excess of cosmic ray events around the direction of a candidate source. We compare the observed signal to the expected background contribution to search for such excesses. Our candidate sources include different classes of astrophysical objects, such as pulsars, microquasars, magnetars, and selected $\gamma$-ray sources identified by LHAASO. We also consider two single-element target sets: the Galactic center and the Crab Nebula. We analyze observed cosmic ray events with declination between $-90^{\circ}$ and $+45^{\circ}$ and energy starting from 0.1 EeV. While we do not detect any significant excess of events indicating a neutron flux from these candidate sources, we establish upper limits for the neutron fluxes.

Orateur: Dr Danelise de Oliveira Franco (University of Hamburg)

17:20 Energy dependence of the knee in the cosmic-ray spectrum across the Milky Way

The all-particle spectrum of cosmic rays measured at Earth has a knee-like feature around 4 PeV. A priori, it is not clear if this is a local feature specific to the Solar neighbourhood in the Milky Way, or if it is a generic property of the Galactic cosmic-ray spectrum. We argue that combining gamma-ray and cosmic-ray data of LHAASO indicates that the knee is a local feature. In order to demonstrate this, we derive a model for the local cosmic-ray spectrum and composition, consistent with the recent LHAASO measurements of the all-particle spectrum and the mean logarithmic mass in the knee region. We calculate the spectrum of diffuse gamma-ray emission based on this model and find that the expected spectral shape of the diffuse gamma-ray flux disagrees with the LHAASO measurements of the diffuse gamma-ray emission in the 10-100 TeV energy range in the inner and outer Galaxy. We determine the break energy in the CR spectrum expected from these gamma-ray data and find it an energy ten times lower than obtained from local measurements.

Orateur: Clément Prévotat (IAP)

17:30 LHAASO detection of Ultra-high-energy Gamma-Ray Emissions from the Giant Molecular Clouds

Gain Molecular Clouds (GMCs) are massive reservoirs of gas and dust, with masses typically around 10$^{5}$ M$_⊙$. GMCs are critical regions for studying Cosmic Ray (CR) interactions and their effects on interstellar medium (ISM). We selected six GMCs, which are at high galactic latitude and in the field of view of LHAASO. These GMCs are within 1 kpc distance from the Sun. By using the data from the LHAASO-WCDA and KM2A, we studied the gamma-ray emissions with energy above TeV from these GMCs. We find an excess emission in the clouds by performing a stacked analysis of GMCs. The derived spectral agreed with the expected gamma-ray flux produced via pp interactions. We also try to give a limits of the CR “knee” by measuring the UHE gamma-ray emission from the GMCs.

Orateur: Yanhong Yu (University of Science and Technology of China)

17:40 Cherenkov Telescope Array Observatory sensitivity to heavy Galactic Cosmic Rays

Finding the sources responsible for accelerating Galactic Cosmic-Rays (GCRs) to energies up to PeV remains a challenging research topic. Observations of high-energy gamma-rays by the Cherenkov Telescope Array Observatory (CTAO) would help us to identify these sources, called PeVatrons. These gamma-rays emerge from the interaction of CRs with surrounding matter through the π0 process and can be traced in the spectral shape of gamma-rays. Among the galactic sources, Supernova Remnants (SNRs) are considered as potential CR accelerators up to PeV energies due to their large energy budget. Based on the results of the multiwavelength analysis (MWL) of Galactic SNRs (Sharma et al., 2023), RX J1713.7-3946 and HAWC J2227+610 were studied to assess CTAO's sensitivity to observe CRs.
To perform this study, gamma-ray spectra were simulated using Gammapy and Naima for different CR compositions including light CRs (protons) and heavy CRs (CNO, Fe). The radiative model parameters were obtained from the previous MWL study.
The simulations revealed that the sensitivity of CTAO to the spectral shape of gamma-rays, would allow us to distinguish protons from heavy CRs, in case of both sources.

Orateur: Coline Dubos (IJCLab)

17:50 Gamma-ray signatures of particle acceleration at stellar wind termination shocks up to PeV energies

Young massive stellar clusters have recently brought attention as PeVatrons candidates, to explain the knee of the cosmic ray spectrum and how protons can be accelerated to such energy scale in galactic sources. The new detector LHAASO is the first to probe well the photon detection band >0.1 PeV, that can correspond to multi-PeV hadronic cosmic rays. Thus, it enables the use of its gamma-ray data to constrain the galactic particle acceleration models and parameters, and to identify the contribution from the different categories of galactic accelerators to the observed cosmic ray flux, especially in the PeV domain.

To that extent, we model the escape and the transport of cosmic rays from their accelerator to molecular clouds, where a lot of p-p interactions producing gamma rays occur. We are focusing on the case where the source is a young massive star cluster, hence the particles are accelerated in stellar wind termination shocks before escaping. We try to determine in a semi-analytical approach the parameters needed (distance between cloud and source, time, slope of injection, number of stars, etc) to produce an excess in the gamma-ray flux corresponding to PeV cosmic rays, that could be detectable by LHAASO. This enables to constrain the subspace of the parameter space for which a detectable excess could exist, and therefore constrains the subset of systems (cluster+cloud) that could produce such an excess. Then, the goal is to find such systems and compare predictions of the models for the gamma-ray flux to LHAASO data in order to determine more precisely different acceleration parameters, such as the wind termination shock efficiency or the injection spectrum in the interstellar medium. Another goal is to try to explain some of the dark PeVatrons seen by LHAASO with systems star cluster+cloud.

Orateur: Alexandre Inventar (APC Laboratory)

18:00 The environment of pulsar halo progenitors

Since the discovery of TeV halos around the Geminga and B0656+14 pulsars by the HAWC experiment in 2017, many theoretical efforts have been dedicated to understanding this source class. Indeed, assuming that they are probing the environment outside their parent supernova remnant (SNR), the gamma-ray emission hints at a confinement of high energy particles that challenges our current understanding of the CR transport in the average interstellar medium (ISM).
Recent hypotheses, including those proposed by Fang et al. 2020, suggest that such an assumption could be erroneous for middle-aged pulsars. Instead, these pulsars may be located in the downstream of the SNR, where turbulence freshly induced by shock activity significantly alters turbulence conditions.
To settle the issue of the position of the relative position of the pulsar, we propose an evolutionary model which coherently describes the evolution of the SNR as a function of the explosion energy and the ambient gas density and take into account the observed distribution of pulsar kick velocities. These quantities being subject to large variance over the Galaxy, we rely on a Montecarlo approach which gives as a result the probability of a pulsar of a given age to remain behind the SNR.
We also investigate more physically accurate models of pulsars being born in stellar wind bubbles and superbubbles to find the probability of a pulsar being inside a turbulent medium or in the ISM. Finally, considering the pulsar progenitor properties, we give the probability of pulsars of a representative Galactic population being in a turbulent medium as a function of their age.

Orateur: Lioni-Moana Bourguinat (GSSI)

18:10 Observing Scenarios and Multi-messenger Implications for the International Gravitational- Wave Network during O4 and O5

An advanced LIGO and Virgo's third observing run brought another binary neutron star merger (BNS) and the first neutron-star black hole mergers. While no confirmed kilonovae were identified in conjunction with any of these events, continued improvements of analyses surrounding GW170817 allow us to project constraints on the Hubble Constant ($H_0$), the Galactic enrichment from $r$-process nucleosynthesis, and ultra-dense matter possible from forthcoming events. Here, we describe the expected constraints based on the latest expected event rates from the international gravitational-wave network (IGWN) and analyses of GW170817. We show the expected detection rate of gravitational waves and their counterparts, as well as how sensitive potential constraints are to the observed numbers of counterparts. We intend this analysis as support for the community when creating scientifically driven electromagnetic follow-up proposals.

18:20 Monitoring the northern sky and follow-up analysis of the multi-messenger alerts with LHAASO-WCDA

With high duty cycle, wide field of view and high sensitivity, LHAASO-WCDA is a promising facility to monitor very-high-energy transient extra-galactic sources unbiasedly. We developed an real-time monitoring system based on LHAASO-WCDA observations which will send alerts within Half a day at most if there is any detection. In the past one year of operation, the system has detected more then ten flare events from IC 310, 1ES 1959+650, BL Lac, etc., and triggered multi-band follow-up observations including VERITAS, Fermi-LAT, Swift-BAT. At the same time, we are actively following up on multi-band and multi-messenger alerts, including X-ray, GeV, neutrino, etc. In this poster, I will present the preliminary results of the sources detected by the monitoring system and the results of follow-up analysis of neutrino alerts.

Orateur: Shicong Hu (Institute of High Energy Physics, Chinese Academy of Sciences)

18:30 → 20:30 Wine and cheese

mar. 10 décembre

09:00 → 18:00 UHECR / Knee -- CRs

09:00 EGMF1

Orateur: Franco Vazza

09:30 EGMF2

Orateur: Klaus Dolag

10:00 UCR sources search and dipole anisotropies review

Orateur: Teresa Bister

10:30 Coffee

11:00 Smoking guns that UHECRs are produced by BNS mergers

Orateur: Glennys Farrar

11:30 Discussion UHECR sources

12:00 Lunch

13:30 Cosmic ray feedback and magnetic dynamos in galaxy formation

Orateur: Christoph Pfrommer

14:00 Theory propagation <-> GMF

Orateur: Gwenael Giacinti

14:30 Particle Acceleration in Highly Magnetized Turbulent Plasmas

Orateur: Luca Comisso

15:00 CR other experiments and IceTop; connection to HE

Orateur: Denis Soldin

15:30 Coffee

16:00 LHAASO CRs

Orateur: Huihai He

16:30 Galactic diffuse gamma-rays (theory)

Orateur: Andrii Neronov

17:00 Discussion

mer. 11 décembre

09:00 → 12:00 HE-gamma sources

09:00 Cherenkov telescopes new

Orateur: Jim Hinton

09:30 Leptonic/PSW nebula

Orateur: Dmitriy Khangulyan

10:00 TeV halos

Orateur: Tim Linden

10:30 Coffee

11:00 SNR acceleration

Orateur: Jacco Vink

11:30 SNR Hadronic PeVatrons observations

Orateur: Ruizhi Yang

12:00 → 13:30 Lunch

13:30 → 15:00 MM

13:30 Hadronic PeVatrons/Super-bubbles

Orateur: Thibault Vieu

14:00 High-Energy Multimessenger Emission from Supermassive Black Holes

Orateur: Kohta Murase

14:30 Discussion

15:00 → 15:30 Coffee

15:30 → 17:20 POSTER SESSION 2

17:20 → 19:20 Wine and cheese

jeu. 12 décembre

09:00 → 18:30 Neutrinos

09:00 General update neutrinos

Orateur: Francis Halzen

10:00 The ANTARES legacy results

Orateur: Antoine Kouchner

10:30 Coffee

11:00 Baikal GVD

Orateur: Rastislav Dvornicky

11:30 IceCube from MeV to PeV

Orateur: Erin O'Sullivan

12:00 KM3NeT from MeV to PeV

Orateur: Aart Heijboer

12:30 Lunch

14:00 Radio detection of neutrinos

Orateur: Kumiko Kotera

14:30 Galactic neutrino searches (combined)

Orateur: Naoko Kurahashi

15:00 High energy astrophysical neutrinos: Open questions and future prospects

The main goals of high-energy neutrino astronomy are to identify the sources of high-energy cosmic rays, particularly ultra-high-energy ones, and to provide information on the acceleration process and constraints on models of high-energy astronomical objects. The detection of high-energy astronomical neutrinos demonstrates the potential for achieving these goals. I will discuss what we have learned from current neutrino observations and the prospects for making progress on identifying the sources.

Orateur: Eli Waxman

15:30 Coffee

15:30 Discussion

16:30 MM in transients

Orateur: Walter Winter

17:00 Real-time astronomy

Orateur: Marcos Santander

17:30 Connection gamma-neutrino-CR

Orateur: Foteini Oikonomou

18:00 New physics with neutrino telescopes

Orateur: Carlos Argüelles

20:00 → 22:00 Conference dinner

ven. 13 décembre

09:00 → 12:30 Low-energy CRs -- "Escape problem"

09:00 DAMPE: B/C, heavier nuclei, e^++e^-

Orateur: Francesca Alemanno

09:30 CALET, B/C, heavier nuclei, e^++e^-

Orateur: Paolo Maestro

10:00 AMS-02: Be9/10, escape times

Orateur: Alberto Oliva

10:30 Coffee

11:00 Interpretation breaks 200GV, 10TV: source/diffusion

Orateur: Carmelo Evoli

12:00 Discussion

12:30 → 13:15 Conference summary

Orateur: Stefano Gabici