Astroparticles and pulsars: connections from low to ultrahigh energies – APACHE

Theoretical and numerical modeling of propagation and interaction of high-energy astroparticles. Particle-In-Cell simulations.
Hadronic simulations of air-showers and radio emission (for the GRAND project and for the interaction of pulsar winds with companion atmospheres).

>>We have presented the first individual and stacking systematic search for gamma-ray emission in the GeV band in the directions of 45 superluminous supernovae (SLSNe) with the Fermi Large Area Telescope (LAT). No excess of gamma-rays from the SLSN positions was found. We report gamma-ray luminosity upper limits and discuss the implication of these results on the origin of SLSNe and, in particular, the scenario of central compact object-aided SNe. We provide upper limits on the gamma-ray flux from these objects either stacked or individual. We find that these limits already constrain the parameters of the possible central pulsar.

>>We have provided a simple and robust criterion to asses the detectability of neutrino flares associated with photon flares, considering a broad range of explosive transients. In this analytical work, we derived a simple estimate of the minimal photon flux necessary for neutrino detection based on two main observables, the bolometric luminosity and the time variability of the emission. It allows to point the most promising sources for transient neutrino emission and thus for multi-messenger studies.

>> We have obtained strong results with the PIC simulation code ZELTRON, applied to pulsar magnetospheres. We show for the first time that ion acceleration is possible, up to ultra-high energies, in the pulsar magnetospheres. A publication is in preparation (Guépin, Cerutti & Kotera, in prep.)

>> The study of pulsar winds via binary systems has also kept its promises. We were able to conclude that in certain systems, the illumination of one side of the companion due to heating by the pulsar wind, implies that particles are accelerated beyond 100 TeV in the wind, at the companion distance. This is a constraining and robust result, which should have an important impact on the community. A publication has been submitted. (Zilles, Kotera, Rohrmann, & Althaus)

With the advent of multi-messenger astronomy, the prospects are bright for this ANR. We are currently exploring neutron star mergers as sources of the highest energy astroparticles using the models developed in this ANR. The prospects for the GRAND project are also promising, with the End-to-End simulation chain converging, and a White Paper published.

C. Guépin, K. Kotera, Can we observe neutrino flares in coincidence with explosive transients?, 2017, A&A, 603, A76, arXiv:1701.07038

N. Renault-Tinacci, K. Kotera, A. Neronov, S. Ando, Search for gamma-ray emission from super- luminous supernovae with the Fermi-LAT, 2017, A&A, 611, A45, arXiv:1708.08971

C. Guépin, K. Kotera, E. Barausse, K. Fang, K. Murase, Ultra-High Energy Cosmic Rays and Neu- trinos from Tidal Disruptions by Massive Black Holes, 2017, accepted by A&A, arXiv:1711.11274

C. Guépin, L. Rinchiuso, K. Kotera, E. Moulin, T. Pierog, J. Silk, Pevatron at the Galactic Center: Multi-Wavelength Signatures from Millisecond Pulsars, 2018, JCAP, Issue 07, 042, arXiv:1806.03307

A. Zilles, O. Martineau, K. Kotera, M. Tueros, K. de Vries, W. Jr. Carvalho, V. Niess, N. Renault- Tinacci, V. Decoene, Radio Morphing: towards a fast computation of the radio signal from air showers, 2018, accepted by Astroparticle Physics, arXiv:1811.01750

The GRAND Collaboration: The Giant Radio Array for Neutrino Detection (GRAND): Science and Design, 2018, to be published in Science China Physics arXiv:1810.09994

Since their discovery more than a hundred years ago, cosmic rays have provided a well of excitement and enigma for particle physicists and astrophysicists, with their colossal energies, and their mysterious extra-solar origins. A connection between cosmic rays and pulsars was suggested in the decades following the discovery of the first pulsar, but was never deeply investigated, in particular at the highest energies. The recent multi-messenger data related to cosmic-rays and the boom in pulsar observations make it timely to dig into this matter now. In this project, we propose to explore the links between astroparticles and pulsars at high and ultrahigh energies. Our recent works have shown that the production of high and ultrahigh energy cosmic rays in these objects could give a picture that is surprisingly consistent with the latest observational data. We will explore the signatures associated to such a source model in terms of multi-messengers (cosmic rays, neutrinos, photons at different wavelengths and gravitational waves). Some of these signatures reveal how astroparticles interact with the neutron star surrounding medium. Our novel approach is to use them as tools to diagnose the nature of pulsars and their winds, and to provide solutions to the latest observational enigmas such as Fast Radio Bursts, Crab flares, and puzzling light curves from millisecond pulsar binary systems. These subjects are being treated in the literature from the classical radio, optical or gamma-ray points of view. We propose to tackle these issues from the high-energy multi-messenger direction. This direction is natural as all these objects are connected to non-thermal emissions.

The theoretical bulk of this proposal is complemented by a significant experimental involvement in the nascent GRAND project. We will apply this work on pulsars specifically to the GRAND experiment, to build and consolidate its science case and orient its technological development and design.

The team gathers most of the (junior) key actors in France in this field, and unites the complementary worldwide recognized expertise of 9 junior and 3 senior researchers from French laboratories, and 4 international collaborators. The success of the project relies on the contract extension of 1 year of an existing postdoc, and the hiring of one postdoc for 2 years. The proposal involves the training of one Ph.D student already supported by a Lagrange Institute Fellowship. The timing would be perfect to consolidate a blossoming team, and start a new thematic at the host institute.

The current proposal has been funded by the Programme National des Hautes Energies and for the year 2015 by Sorbonne Universités (67.7 kE). This allowed us to hire a postdoctoral scholar last year and to already make good progress on this investigation.

This project will be important to achieve the goals of the high-energy astrophysics oriented scientific enterprise conducted in France and in Europe. International workshops will be organized that will constitute milestones to evaluate the progress and establish a tight connection between the different astrophysics communities linked to this original and timely thematic.