In this study, we investigate the gravitational collapses of rotating stellar systems accounting for gamma-ray burst jet progenitors. Based on the virial theorem of hadron collisional relaxations and Newtonian slow-rotating approximation, we analyze the conversion of gravitational binding energy into kinetic energy of hadrons, whose collisions produce photons and electron-positron pairs forming fireballs. Our qualitative analysis implies that rotation effects collimated and spinning fireballs with nontrivial angular momenta along the propagating direction, thus making ultra-relativistic jets. Results reveal the possible trends that the fireball becomes more collimated and the jet angle decreases as the total angular momentum and mass ratio $\textit{J}$/$\textit{M}$ of the slow-rotating collapsing core increases. Discussing the extrapolation of these trends to fast-rotating collapsing systems, we speculate that the ratio $\textit{J}$/$\textit{M}$ should be a key quantity for differentiating long bursts (massive core collapses) from short bursts (binary coalescence). We derive the intrinsic correlations of collimated fireball quantities that should be imprinted on a large sample of observed GRB data as empirical correlations.

Italy

China

She-Sheng Xue

Collimated and spinning fireballs for ultra-relativistic jets: long vs short gamma-ray bursts by angular momentum and mass ratio

In this paper, we investigate a <math altimg='si1.svg'><mo stretchy='false'>(</mo><mn>1</mn><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mn>3</mn><mo stretchy='false'>)</mo></math>-dimensional static Friedmann-Robertson-Walker (FRW) space-time, pierced by a cosmic string. Our analysis begins with a detail study of the geodesic motion of photon rays in this curved background, focusing on the behavior of the associated effective potential. This allows us to understand how the cosmic string and curvature of space-time influence the trajectories of light rays. Moving beyond ray optics, we explore wave optics by solving the covariant Helmholtz equation in this gravitational setting. By transforming the resulting radial equation into a Schr&#246;dinger-like form, we extract an effective potential and derive a frequency-dependent refractive index. This refractive index shows the combined effects of the cosmic string and the curvature parameter, showing their influence on the wave propagation. Furthermore, we extend our study to a <math altimg='si2.svg'><mo stretchy='false'>(</mo><mn>1</mn><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mn>2</mn><mo stretchy='false'>)</mo></math>-dimensional space-time with disclinations, where we analyze the wave optics phenomena. Through the Helmholtz equation in this lower-dimensional case, we determine the refractive index and discuss how it is affected by the geometric parameters of this lower-dimensional space-time. Through both geometric and wave optics approaches, our work provides a comprehensive understanding of how topological defects and curvature impact geometric and physical optics in curved space-time of three- and four-dimensions.

India

Faizuddin Ahmed

Algeria

Abdelmalek Bouzenada

Ray and wave dynamics in a static FRW spacetime with conical singularity

Detection of sub-GeV dark matter (DM) particles in direct detection experiments is inherently difficult, as their low kinetic energies in the galactic halo are insufficient to produce observable recoils of the heavy nuclei in the detectors. On the other hand, whenever DM particles interact with nucleons, they can be accelerated by scattering with galactic cosmic rays. These cosmic-ray-boosted DM particles can then interact not only through coherent elastic scattering with nuclei, but also through scattering with individual nucleons in the detectors and produce outgoing particles at MeV to GeV kinetic energies. The resulting signal spectrum overlaps with the detection capabilities of modern neutrino experiments. One future experiment is the Deep Underground Neutrino Experiment (DUNE) at the Sanford Underground Research Facility. Our study shows that DUNE has a unique ability to search for cosmic-ray boosted DM with sensitivity comparable to dedicated direct detection experiments in the case of spin-independent interactions. Importantly, DUNE’s sensitivity reaches similar values of DM-nucleon cross sections also in the case of spin-dependent interactions, offering a key advantage over traditional direct detection experiments.

Switzerland

Richard Diurba

Norway

Helena Kolešová

Prospects of detecting cosmic ray up-scattered dark matter with DUNE

Dark photons that are sufficiently light and/or weakly interacting represent a compelling vision of dark matter. Dark photon decay into three photons, which we call the dark photon trident, can be the dominant channel when the dark photon mass falls below the electron pair threshold and can produce a significant flux of x rays. We use 16 years of data from Interrnational Gamma-Ray Astro Physics Laboratory (INTEGRAL)/Spectrometer of INTEGRAL (SPI) to constrain sub-MeV dark photon decay, producing new worlds-best constraints on the kinetic mixing parameter for dark photon masses between 90 and 1022 keV, and comment on the potential for future x-ray observatories to discover the trident decay process.

Sweden

Tim Linden

Thong T.Q. Nguyen

United States

Tim M.P. Tait

X-ray constraints on dark photon tridents

This study investigates ray trajectories and wave propagation in a static, <math altimg='si1.svg'><mo stretchy='false'>(</mo><mn>2</mn><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mn>1</mn><mo stretchy='false'>)</mo></math>-dimensional, radially symmetric traversable wormhole (TWH) spacetime with a constant redshift function and a radial shape function proportional to <math altimg='si2.svg'><mn>1</mn><mo stretchy='false'>/</mo><mi>&#961;</mi></math>. The spatial geometry forms a minimal surface (a catenoid bridge), enabling a geometric-optical interpretation. An analysis of the ray trajectories reveals how the curvature-induced structure of the wormhole (WH) governs the ray paths, depending on the relative sizes of the radial coordinate <italic>&#961;</italic> and the throat radius <math altimg='si26.svg'><msub><mrow><mi>&#8467;</mi></mrow><mrow><mo>&#8728;</mo></mrow></msub></math>. Extending the study to wave dynamics, we derive a refractive index <math altimg='si4.svg'><mi>n</mi><mo stretchy='false'>(</mo><mi>&#961;</mi><mo>,</mo><mi>&#969;</mi><mo stretchy='false'>)</mo></math> that explicitly depends on both <italic>&#961;</italic> and the wave frequency <italic>&#969;</italic>, identifying a critical frequency that marks the transition between propagation and attenuation. These results demonstrate how the WH's topology distinctly influences wave propagation and may inform future developments in analogue gravity models and advanced optical media.

Türkiye

Semra Gurtas Dogan

Abdullah Guvendi

Omar Mustafa

Ray trajectories and wave optics in a traversable wormhole: Optics of a minimal surface

We present a novel way to probe inelastic dark matter using cosmic-ray (CR) cooling in active galactic nuclei (AGNs). Dark matter (DM) in the vicinity of supermassive black holes may scatter off CRs, resulting in the rapid cooling of CRs for sufficiently large cross sections. This in turn can alter the high-energy neutrino and gamma-ray fluxes detected from these sources. We show that AGN cooling bounds obtained through the multimessenger data of NGC 1068 and TXS <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0506</mn><mo>+</mo><mn>056</mn></mrow></math> allows us to reach unprecedently large mass splittings for inelastic DM (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>≳</mo><mi>TeV</mi></math>), orders of magnitude larger than those probed by direct detection experiments and DM capture in neutron stars. Furthermore, we demonstrate that cooling bounds from AGNs can probe thermal light DM with small mass splittings. This provides novel and complementary constraints in parts of a parameter space accessible solely by colliders and beam-dump experiments.

Japan

R. Andrew Gustafson

Gonzalo Herrera

Mainak Mukhopadhyay

Kohta Murase

Ian M. Shoemaker

Cosmic-ray cooling in active galactic nuclei as a new probe of inelastic dark matter

While dual-phase xenon time projection chambers have driven the sensitivity toward weakly interacting massive particles at the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>TeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> mass scale, the scope for sub-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> dark matter particles is hindered by a limited nuclear recoil energy detection threshold. One approach to probe for lighter candidates is to consider cases where they have been boosted by collisions with cosmic rays in the Milky Way, such that the additional kinetic energy lifts their induced signatures above the nominal threshold. In this Letter, we report first results of a search for cosmic ray-boosted dark matter (CRDM) with a combined <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>4.2</mn><mtext> </mtext><mtext> </mtext><mi>metric</mi><mtext> </mtext><mi>ton</mi><mo>/</mo><mi>yr</mi></mrow></math> exposure from the LUX-ZEPLIN experiment. We observe no excess above the expected backgrounds and establish world-leading constraints on the spin-independent CRDM-nucleon cross section as small as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.9</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>33</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> at 90% confidence level for sub-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> masses.

J. Aalbers

D.S. Akerib

United Kingdom

A.K. Al Musalhi

F. Alder

C.S. Amarasinghe

A. Ames

T.J. Anderson

N. Angelides

H.M. Araújo

J.E. Armstrong

M. Arthurs

A. Baker

S. Balashov

J. Bang

J.W. Bargemann

E.E. Barillier

K. Beattie

T. Benson

A. Bhatti

A. Biekert

T.P. Biesiadzinski

H.J. Birch

E. Bishop

G.M. Blockinger

B. Boxer

C.A.J. Brew

Portugal

P. Brás

S. Burdin

M. Buuck

M.C. Carmona-Benitez

M. Carter

A. Chawla

H. Chen

J.J. Cherwinka

Y.T. Chin

N.I. Chott

M.V. Converse

R. Coronel

A. Cottle

G. Cox

D. Curran

C.E. Dahl

I. Darlington

S. Dave

A. David

J. Delgaudio

S. Dey

L. de Viveiros

L. Di Felice

C. Ding

J.E.Y. Dobson

E. Druszkiewicz

S. Dubey

S.R. Eriksen

A. Fan

N.M. Fearon

N. Fieldhouse

S. Fiorucci

H. Flaecher

E.D. Fraser

Australia

T.M.A. Fruth

R.J. Gaitskell

A. Geffre

J. Genovesi

C. Ghag

R. Gibbons

S. Gokhale

J. Green

M.G.D. van der Grinten

J.J. Haiston

C.R. Hall

T. Hall

S. Han

E. Hartigan-O’Connor

S.J. Haselschwardt

M.A. Hernandez

S.A. Hertel

G. Heuermann

G.J. Homenides

M. Horn

D.Q. Huang

D. Hunt

E. Jacquet

R.S. James

M.K. Kannichankandy

A.C. Kaboth

A.C. Kamaha

D. Khaitan

A. Khazov

J. Kim

South Korea

Y.D. Kim

J. Kingston

R. Kirk

D. Kodroff

L. Korley

E.V. Korolkova

H. Kraus

S. Kravitz

L. Kreczko

V.A. Kudryavtsev

New Constraints on Cosmic Ray-Boosted Dark Matter from the LUX-ZEPLIN Experiment

This paper explores the application of Compton scattering imaging for the active detection of space debris at long distances and through dense metallic shielding. Unlike conventional short-range applications in security screening, space-based scenarios present unique challenges such as severe geometric attenuation, low signal-to-noise ratios, and multi-layer scattering interference. To address these issues, we developed a high-precision, single-sided X-ray scattering imaging system capable of long-range detection. By integrating optimized scattering models, advanced noise suppression algorithms, and a carefully designed experimental setup, the system successfully imaged targets behind 3-mm aluminum shielding at a testing distance of 1.76 meters—equivalent to 10 km in a space environment—with a spatial resolution of 0.63 cm. The results validate the feasibility of Compton scattering imaging for active space debris monitoring and mark significant progress in long-range imaging under complex electromagnetic conditions.

Yun Li

Tong Su

Lizhi Sheng

Ruili Zhang

Pengfei Qiang

Rengzhou Zheng

Bo Wang

Yongqing Yan

Yue Li

Yalong Zhang

Compton scattering X-ray imaging system for material detection through 3 mm aluminum shielding for potential future space application

We study multi-component dark matter scenarios and the Galactic 511 keV $\textit{γ}$-ray emission line signal in the framework of a local, dark U(1) extension of the Standard Model. A light vector dark matter particle associated with the dark U(1) may decay and annihilate to electron-positron pairs. The produced positrons may in turn form positroniums that subsequently annihilate to two photons, accounting for the observed line signal of the Galactic 511 keV $\textit{γ}$-ray emission. Three scenarios are investigated. First, we consider the minimal U(1) extension where a dark gauge boson and a dark Higgs boson are newly introduced to the particle content. As a second scenario, we consider WIMP-type dark matter with the introduction of an extra dark fermion which, in addition to the dark gauge boson, may contribute to the dark matter relic abundance. It is thus a multi-component dark matter scenario with a UV-complete dark U(1) symmetry. In particular, the vector dark matter may account for a small fraction of the total dark matter relic abundance. Finally, we consider the scenario where the dark matter particles are of the FIMP-type. In this case, both the light vector and fermion dark matter particles may be produced via the freeze-in and super-WIMP mechanisms. Considering theoretical and observational constraints, we explore the allowed parameter space where the Galactic 511 keV $\textit{γ}$-ray line signal and the dark matter relic can both be explained. We also discuss possible observational signatures.

Germany

Sarif Khan

Jinsu Kim

Jongkuk Kim

Pyungwon Ko

Multi-component dark matter and Galactic 511 keV $\textit{γ}$-ray emission

Interesting data on Gamma Ray Burts (GRBs) and Cosmic Rays (CRs) have recently been made public. GRB221009A has a record “peak energy”. The CR electron spectrum has been measured to unprecedented high energies and exhibits a “knee” akin to the ones in all-particle or individual-element CR nuclei. IceCube has not seen high-energy neutrinos associated with GRBs. AMS has published a CR positron spectrum conducive to much speculation. We examine these data in the light of the “CannonBall Model” of GRBs and CRs, in which they are intimately related and which they do strongly validate.

Spain

A. De Rújula

A revamped understanding of Cosmic Rays and Gamma-Ray Bursts