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Newsletter February 2026

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Dear all,

This is February’s edition of the newsletter of the COST action. The aim is to keep you updated on recent and upcoming conferences and postdoc positions on subjects related to WISPs.

 

Cosmic Wispers preprints

The gravitational wave landscape of cosmic string networks with varying tension

Luca Brunelli, Filippo Revello, Gonzalo Villa

https://arxiv.org/abs/2601.10790

We fully classify the phenomenology of gravitational wave emission from scaling cosmic string networks with varying tension and compute the spectral indices of the resulting stochastic backgrounds. In string compactifications, periods of varying tension occur when moduli acquire a time-dependence. We present concrete examples in type IIB string theory as D3- and NS5- branes wrapping internal cycles, which become dynamical due to the effect of moduli potentials. Moreover, we use Swampland constraints to derive general bounds on the allowed time-variation of the effective string tension in FLRW backgrounds and on the resulting spectral indices



Resonant Axion-Photon Conversion in the Early Inspiral of Neutron Star Binaries

D. Suárez-Fontanella, M. Ángeles Pérez-García, C. Albertus

https://arxiv.org/abs/2602.15065

We consider the early binary neutron star inspiral phase as a scenario to probe environmental axion--photon resonant conversion. For this we approximately model the merger site electromagnetic fields as the superposition of two rotating dipolar stellar magnetic fields at the thousand--km scale when both magnetospheres are not largely distorted. We capture the time-sliced near-zone magnetospheric geometry relevant for axion--photon mixing. Plasma effects are incorporated through an effective Goldreich--Julian charge density, used to determine the effective plasma frequency and the location of resonant conversion surfaces. Our results show that axion--photon resonant conversion in binary magnetospheres mostly occurs on extended peanut-shaped surfaces whose global geometry evolves as the binary inspiral evolves. As a consequence, the total electromagnetic power emitted through axion--photon conversion exhibits a characteristic dependence on axion mass and a slow temporal modulation correlated with the gravitational wave frequency emission. This feature is potentially detectable for ma∈[50,170]μeV and set gaγ≲10−11 GeV−1 as it lies within the sensitivity limits of current or planned radio observation missions. In light of our results we discuss the opportunity of binary neutron star inspirals as time-dependent, multimessenger probes of axion physics, and motivate coordinated searches combining gravitational wave observations with radio and millimeter wavelength electromagnetic measurements



Gravitational-Wave Signals for Supernova Explosions of Three-Dimensional Progenitors

Alessandro Lella, Giuseppe Lucente, Daniel Kresse, Robert Glas, H.-Thomas Janka, Alessandro Mirizzi

https://arxiv.org/abs/2602.02651

Core-collapse supernovae (SNe) are sources of gravitational waves (GWs) produced by hydrodynamical instabilities and highly time-dependent anisotropies of the neutrino radiation. In this work we analyze both contributions to the GW signal for two state-of-the-art three-dimensional (3D) SN models computed with the Prometheus-Vertex neutrino-hydrodynamics code. In contrast to the far majority of models analyzed for GWs so far, our core-collapse simulations were started with 12.28 M_sun (18.88 M_sun) progenitors, whose final hour (7 min) of convective oxygen-shell burning was computed in 3D and featured a vigorous oxygen-neon shell merger. The corresponding large-scale asymmetries in the oxygen layer are conducive to buoyancy-aided neutrino-driven explosions. The models were continuously evolved in 3D from the pre-collapse evolution until 5.11 s (1.68 s) after the core bounce. The GW signals result from the well-known dynamical phenomena in the SN core such as prompt postshock convection, neutrino-driven convection, the standing accretion shock instability, proto-neutron star oscillations, and anisotropic ejecta expansion. They do not exhibit any new or specific features that can be unambiguously connected to the powerful pre-collapse activity in the progenitors, but we identify interesting differences compared to results in the literature. We also discuss measurement prospects by interferometers, confirming that GW signals from future Galactic SNe will be detectable with existing and next-generation experiments working in the frequency range f ~ 1-2000 Hz.



Stochastic galactic supernova flux of semi-relativistic particles

David Alonso-González, David Cerdeño, Marina Cermeño, Andres D. Perez

https://arxiv.org/abs/2602.17597

This work studies the flux of semi-relativistic particles from past galactic core-collapse supernovae reaching terrestrial detectors. We derive a numerical simulation of the full galactic supernova history and show that the resulting flux at Earth is intrinsically stochastic rather than smooth, as it is shaped by the narrow energy contributions of individual events. This leads to important consequences for the expected spectral features in terrestrial experiments and for interpreting constraints on light exotic particles. The code used to generate our simulation is shared open access.

We encourage participants in the COST action to send us a small summary, typically smaller than the abstract, of their own articles that will appear in the arXiv (after they appear, with their arXiv numbers). The summary will be disseminated in the newsletter.

Send email to 

Alessandro Lella alessandro.lella@ba.infn.it

Damiano Fiorillo damianofg@gmail.com

with subject: preprint summary for Cosmic WISPers newsletter.



PhD/Postdoc/Junior Positions

  • February

    • Postdoctoral positions in particle physics phenomenology, astroparticle physics and cosmology, Chungnam Natl. U. (CNU) link

    • Junior research fellows on theoretical nuclear physics, nuclear astrophysics, astroparticle physics and cosmology, Institute of Physics, Academia Sinica, Taiwan link

  • March

    • Postdoctoral positions, University of Minnesota, Minneapolis link

    • Postdoctoral position, Max Planck Institute, Garching link

  • April

    • Postdoctoral positions in supernova neutrino physics, Beijing link

    • Postdoctoral positions for cosmic exotic particle search, USTC, Hefei link

  • May

    • PhD positions in Astrophysics, Cosmology and Gravitation, Espirito Santo Univeristy, South America. link




Conferences

  • March

    • GGI PhD School on "Theoretical Aspects of Astroparticle Physics, Cosmology and Gravitation" link

    • 60th Rencontres de Moriond on Very High Energy Phenomena in the Universe: Moriond VHEPU 2026 link

    • 2nd UNDARK School link

  • April

    • 7th Edition of the international conference Progress on Old and New Themes in cosmology (PONT 2026) link

  • May

    • UniVersum VII -- Naples 2026 link

    • SCALE 2026: Strings & Cosmology – All Lengths Explored (SCALE) link

    • Planck2026 & 6th EuCAPT Symposium link

  • June

    • 16th International Workshop on the Identification of Dark Matter 2026 (IDM 2026) link

    • 32nd International Conference on Neutrino Physics and Astrophysics (Neutrino 2026) link

    • PASCOS 2026: The 31st International Symposium on Particles, Strings, and Cosmology (PASCOS2026) link

    • Black Holes & Cosmology 2026 (BHCos26) link

    • 4th Training School of the COST Action CA21106: Cosmic WISPers link

    • 4th General Meeting of the COST Action: Cosmic WISPers (CA21106) link

    • Primordial Cosmology: Novel Perspectives from Scattering Amplitudes, Holography and the Bootstrap link

  • July

    • Exploring New Frontiers in Cosmology: GGI Workshop link

    • Dark Matter and Stars: Multi-Messenger Probes of Dark Matter and Modified Gravity (icdms2026) link

    • Axions in Seoul 2026: Frontiers in Theory, Cosmology, and Experiment (AiS 2026) link

  • August

    • XVI International Conference on Gravitation, Astrophysics and Cosmology (ICGAC16) link

    • Invisibles 26 link

    • Listening to the Cosmos: New Frontiers in Gravitational Wave Physics link

    • COSMO-26: 29th International Conference on Particle Physics & Cosmology link

  • September

    • Erice International School/Workshop of Nuclear Physics, 47th course on 'Neutrinos in Cosmology,in Astro-, Particle- and Nuclear Physics' link

  • November

    • 21st Patras Workshop on Axions, WIMPs and WISPs link