Pub Date : 2026-05-01Epub Date: 2026-01-23DOI: 10.1016/j.astropartphys.2026.103215
Joong Hyun Kim , Sinchul Kang , HyeoungWoo Park , Jungho Kim , Hyeonseo Park , Young Soo Yoon , Hongjoo Kim , Yeongduk Kim , Jungho So , SungHyun Kim
We report on the measurement of neutron energy spectra at the newly established Yemi Underground Laboratory (Yemilab) in the Republic of Korea, designed to host dark matter and rare-event search experiments. A high-sensitivity neutron spectrometer was employed, consisting of ten cylindrical 3He proportional counters, eight of which were embedded in cylindrical high-density polyethylene moderators of various sizes. To quantify and mitigate contributions from internal -backgrounds, each detector underwent a dedicated background measurement using a cadmium-shielded box. These backgrounds, primarily originating from trace amounts of U and Th in the stainless-steel housings, were characterized and subtracted during data analysis. Neutron measurements were carried out at three locations within the Yemilab between March to October 2023. After waveform-based event selection and correction for -backgrounds, neutron count rates were estimated and corresponding energy spectra were reconstructed using the unfolding method. The total neutron fluence rates were measured ranged from to , with thermal and fast neutron components (1–10 ) ranging from to and to , respectively.
{"title":"Neutron spectrum measurement in the Yemi underground laboratory","authors":"Joong Hyun Kim , Sinchul Kang , HyeoungWoo Park , Jungho Kim , Hyeonseo Park , Young Soo Yoon , Hongjoo Kim , Yeongduk Kim , Jungho So , SungHyun Kim","doi":"10.1016/j.astropartphys.2026.103215","DOIUrl":"10.1016/j.astropartphys.2026.103215","url":null,"abstract":"<div><div>We report on the measurement of neutron energy spectra at the newly established Yemi Underground Laboratory (Yemilab) in the Republic of Korea, designed to host dark matter and rare-event search experiments. A high-sensitivity neutron spectrometer was employed, consisting of ten cylindrical <sup>3</sup>He proportional counters, eight of which were embedded in cylindrical high-density polyethylene moderators of various sizes. To quantify and mitigate contributions from internal <span><math><mi>α</mi></math></span>-backgrounds, each detector underwent a dedicated background measurement using a cadmium-shielded box. These backgrounds, primarily originating from trace amounts of U and Th in the stainless-steel housings, were characterized and subtracted during data analysis. Neutron measurements were carried out at three locations within the Yemilab between March to October 2023. After waveform-based event selection and correction for <span><math><mi>α</mi></math></span>-backgrounds, neutron count rates were estimated and corresponding energy spectra were reconstructed using the unfolding method. The total neutron fluence rates were measured ranged from <span><math><mrow><mo>(</mo><mn>3</mn><mo>.</mo><mn>24</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>11</mn><mo>)</mo></mrow></math></span> to <span><math><mrow><mrow><mo>(</mo><mn>4</mn><mo>.</mo><mn>01</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>10</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, with thermal and fast neutron components (1–10 <span><math><mi>MeV</mi></math></span>) ranging from <span><math><mrow><mo>(</mo><mn>1</mn><mo>.</mo><mn>32</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>05</mn><mo>)</mo></mrow></math></span> to <span><math><mrow><mrow><mo>(</mo><mn>1</mn><mo>.</mo><mn>51</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>05</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> and <span><math><mrow><mo>(</mo><mn>0</mn><mo>.</mo><mn>27</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>03</mn><mo>)</mo></mrow></math></span> to <span><math><mrow><mrow><mo>(</mo><mn>0</mn><mo>.</mo><mn>34</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>10</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, respectively.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"177 ","pages":"Article 103215"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-20DOI: 10.1016/j.astropartphys.2026.103214
Lucas M. Pasquevich , Gustavo E. Romero , Matías M. Reynoso
Ultraluminous X-ray sources (ULXs) are point-like sources that exhibit apparent X-ray luminosities exceeding the Eddington limit for stellar-mass compact objects. A widely accepted interpretation is that these systems are X-ray binaries accreting matter possibly at super-Eddington rates. In this regime, photon trapping inflates the accretion disk, making it geometrically and optically thick. Radiation-driven winds launched from the supercritical disk form funnel-shaped walls along the symmetry axis. While the apparent X-ray luminosity can exceed the Eddington limit due to geometrical beaming within this funnel, a misalignment with the observer’s line of sight strongly suppresses the X-ray emission, rendering the ULX electromagnetically obscured.
This work explores the potential for high-energy neutrino production in black hole-hosting ULXs. We model proton acceleration via magnetic reconnection in the region above the super-accreting black hole. Although electromagnetic emission is efficiently absorbed by the dense wind and radiation fields, neutrinos generated from photomeson interactions can escape. Our model self-consistently accounts for energy losses of pions and muons in this environment. The results indicate that misaligned, electromagnetically obscured Galactic ULXs could produce a neutrino flux detectable by instruments like KM3NeT and IceCube within several years of observation.
{"title":"Neutrinos from hidden ultraluminous X-ray sources in the Galaxy","authors":"Lucas M. Pasquevich , Gustavo E. Romero , Matías M. Reynoso","doi":"10.1016/j.astropartphys.2026.103214","DOIUrl":"10.1016/j.astropartphys.2026.103214","url":null,"abstract":"<div><div>Ultraluminous X-ray sources (ULXs) are point-like sources that exhibit apparent X-ray luminosities exceeding the Eddington limit for stellar-mass compact objects. A widely accepted interpretation is that these systems are X-ray binaries accreting matter possibly at super-Eddington rates. In this regime, photon trapping inflates the accretion disk, making it geometrically and optically thick. Radiation-driven winds launched from the supercritical disk form funnel-shaped walls along the symmetry axis. While the apparent X-ray luminosity can exceed the Eddington limit due to geometrical beaming within this funnel, a misalignment with the observer’s line of sight strongly suppresses the X-ray emission, rendering the ULX electromagnetically obscured.</div><div>This work explores the potential for high-energy neutrino production in black hole-hosting ULXs. We model proton acceleration via magnetic reconnection in the region above the super-accreting black hole. Although electromagnetic emission is efficiently absorbed by the dense wind and radiation fields, neutrinos generated from photomeson interactions can escape. Our model self-consistently accounts for energy losses of pions and muons in this environment. The results indicate that misaligned, electromagnetically obscured Galactic ULXs could produce a neutrino flux detectable by instruments like KM3NeT and IceCube within several years of observation.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"177 ","pages":"Article 103214"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146015540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate how the large-scale heliosphere alters the arrival directions of high-energy cosmic-ray electrons and positrons and ask if and when this “heliospheric lens” can be ignored for anisotropy and source — association studies — an especially timely topic given, for instance, the persistent cosmic-ray positron fraction and its unknown origin. Using a modular back-tracing framework, we explore a set of widely used magnetic-field descriptions—from a Parker spiral baseline to more structured configurations that include latitudinal wind contrasts, Smith–Bieber–type azimuthal strengthening, and tilted or wavy heliospheric current sheets. We model the deterministic deflections of high-energy cosmic-ray electrons and positrons (CREs) induced by large-scale heliospheric magnetic-field structures using a back-tracing approach. Our results apply to CREs above tens of GeV, where diffusion, convection, and adiabatic energy losses play a subdominant role; these processes are neglected in the present study and will be addressed in future work. Across these models the picture is consistent: most bending is accumulated within the inner tens of astronomical units and decreases rapidly with energy. Field choices and solar-cycle geometry set the overall normalization, with stronger spiral winding or a more highly tilted current sheet producing larger deflections at the same energy. Differences between electrons and positrons are most apparent at lower energies, where drift histories and current-sheet encounters diverge, and become increasingly small at multi-TeV energies. We summarize these trends with a practical threshold energy describing when heliospheric bending falls below an instrument’s angular resolution, and we verify that our conclusions are robust to numerical settings. For current instruments, heliospheric effects can usually be treated as a small correction at the highest energies, while sub-TeV analyses benefit from a calibrated envelope that accounts for plausible field configurations during the observing epoch.
{"title":"Through the heliospheric lens: Directional deflection of high-energy cosmic-ray electrons and positrons","authors":"Stefano Profumo , Aria Koul , Anika Malladi , Benjamin Schmitt","doi":"10.1016/j.astropartphys.2025.103202","DOIUrl":"10.1016/j.astropartphys.2025.103202","url":null,"abstract":"<div><div>We investigate how the large-scale heliosphere alters the arrival directions of high-energy cosmic-ray electrons and positrons and ask if and when this “heliospheric lens” can be ignored for anisotropy and source — association studies — an especially timely topic given, for instance, the persistent cosmic-ray positron fraction and its unknown origin. Using a modular back-tracing framework, we explore a set of widely used magnetic-field descriptions—from a Parker spiral baseline to more structured configurations that include latitudinal wind contrasts, Smith–Bieber–type azimuthal strengthening, and tilted or wavy heliospheric current sheets. We model the deterministic deflections of high-energy cosmic-ray electrons and positrons (CREs) induced by large-scale heliospheric magnetic-field structures using a back-tracing approach. Our results apply to CREs above tens of GeV, where diffusion, convection, and adiabatic energy losses play a subdominant role; these processes are neglected in the present study and will be addressed in future work. Across these models the picture is consistent: most bending is accumulated within the inner tens of astronomical units and decreases rapidly with energy. Field choices and solar-cycle geometry set the overall normalization, with stronger spiral winding or a more highly tilted current sheet producing larger deflections at the same energy. Differences between electrons and positrons are most apparent at lower energies, where drift histories and current-sheet encounters diverge, and become increasingly small at multi-TeV energies. We summarize these trends with a practical threshold energy describing when heliospheric bending falls below an instrument’s angular resolution, and we verify that our conclusions are robust to numerical settings. For current instruments, heliospheric effects can usually be treated as a small correction at the highest energies, while sub-TeV analyses benefit from a calibrated envelope that accounts for plausible field configurations during the observing epoch.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"176 ","pages":"Article 103202"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145790663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-11-28DOI: 10.1016/j.astropartphys.2025.103201
Francesco Nozzoli
On February 13, 2023, the KM3NeT/ARCA neutrino telescope detected the high-energy neutrino candidate KM3-230213A, characterized by a 120 PeV through-going muon with a nearly horizontal trajectory. Independently, the Yangbajing muon telescope in Tibet recorded a burst of events starting at the same UTC time, showing a excess in a direction compatible with KM3-230213A. The burst exhibits a statistically significant exponential time structure with a decay constant min and a peak flux of Hz/m, resulting in excess events over 30 min. The analysis of the time series of the event rate recorded by the Yangbajing telescope shows that the probability of a chance coincidence of this muon burst with the KM3-230213A event is less than . The agreement between the muon burst and the KM3-230213A event in both timing and direction, together with the non-detection by IceCube and the Pierre Auger Observatory, supports the hypothesis of a rapidly flaring source and highlights the relevance of combining surface muon data with neutrino telescope observations.
{"title":"Investigation of a muon burst coincident with KM3-230213A","authors":"Francesco Nozzoli","doi":"10.1016/j.astropartphys.2025.103201","DOIUrl":"10.1016/j.astropartphys.2025.103201","url":null,"abstract":"<div><div>On February 13, 2023, the KM3NeT/ARCA neutrino telescope detected the high-energy neutrino candidate KM3-230213A, characterized by a <span><math><mo>∼</mo></math></span>120<!--> <!-->PeV through-going muon with a nearly horizontal trajectory. Independently, the Yangbajing muon telescope in Tibet recorded a burst of events starting at the same UTC time, showing a <span><math><mrow><mn>5</mn><mo>.</mo><mn>7</mn><mi>σ</mi></mrow></math></span> excess in a direction compatible with KM3-230213A. The burst exhibits a statistically significant exponential time structure with a decay constant <span><math><mrow><mi>τ</mi><mo>=</mo><mn>7</mn><mo>.</mo><mn>0</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></math></span> min and a peak flux of <span><math><mrow><mn>55</mn><mo>±</mo><mn>10</mn></mrow></math></span> <!--> <!-->Hz/m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>, resulting in <span><math><mrow><mn>2300</mn><mo>±</mo><mn>400</mn></mrow></math></span> excess events over 30 min. The analysis of the time series of the event rate recorded by the Yangbajing telescope shows that the probability of a chance coincidence of this muon burst with the KM3-230213A event is less than <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></math></span>. The agreement between the muon burst and the KM3-230213A event in both timing and direction, together with the non-detection by IceCube and the Pierre Auger Observatory, supports the hypothesis of a rapidly flaring source and highlights the relevance of combining surface muon data with neutrino telescope observations.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"176 ","pages":"Article 103201"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-07DOI: 10.1016/j.astropartphys.2025.103203
M. Borchiellini , D. Maurin , M. Vecchi
Electron-capture (EC) unstable species in Galactic cosmic rays constrain the time elapsed between nucleosynthesis and acceleration. They have also been advocated as tracers of reacceleration or gas inhomogeneities during their transport. The number of EC-unstable species grows with mass, with an expected EC-decay impact more important for larger atomic number and lower energy. We revisit the modelling of EC decay and its detectability in the context of recent unmodulated low-energy (Voyager) and high-precision data for heavy (AMS-02) and very-heavy nuclei (ACE-CRIS, CALET and Super-TIGER). We solve the transport equation for a multi-level configuration (up to any number of electrons attached) in the diffusion and leaky-box models. Their decayed fractions are found to be qualitatively similar but with very different absolute fluxes. We check that the standard two-level approximation, wherein the cosmic-ray nucleus is fully ionised or with one electron attached, is sufficient for most situations. We find that the impact of EC-decay is negligible in current data, except possibly for fluxes or ratios involving 51Cr, 55Fe, and Co. These conclusions are robust against significant uncertainties in the attachment and stripping cross-sections. This first analysis calls for further investigation, as several forthcoming projects (e.g., TIGERISS) are targeting cosmic rays.
{"title":"Revisiting electron-capture decay for Galactic cosmic-ray data","authors":"M. Borchiellini , D. Maurin , M. Vecchi","doi":"10.1016/j.astropartphys.2025.103203","DOIUrl":"10.1016/j.astropartphys.2025.103203","url":null,"abstract":"<div><div>Electron-capture (EC) unstable species in Galactic cosmic rays constrain the time elapsed between nucleosynthesis and acceleration. They have also been advocated as tracers of reacceleration or gas inhomogeneities during their transport. The number of EC-unstable species grows with mass, with an expected EC-decay impact more important for larger atomic number and lower energy. We revisit the modelling of EC decay and its detectability in the context of recent unmodulated low-energy (Voyager) and high-precision data for heavy (AMS-02) and very-heavy nuclei (ACE-CRIS, CALET and Super-TIGER). We solve the transport equation for a multi-level configuration (up to any number of electrons attached) in the diffusion and leaky-box models. Their decayed fractions are found to be qualitatively similar but with very different absolute fluxes. We check that the standard two-level approximation, wherein the cosmic-ray nucleus is fully ionised or with one electron attached, is sufficient for most situations. We find that the impact of EC-decay is negligible in current data, except possibly for fluxes or ratios involving <sup>51</sup>Cr, <sup>55</sup>Fe, and Co. These conclusions are robust against significant uncertainties in the attachment and stripping cross-sections. This first analysis calls for further investigation, as several forthcoming projects (e.g., TIGERISS) are targeting <span><math><mrow><mi>Z</mi><mo>></mo><mn>30</mn></mrow></math></span> cosmic rays.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"176 ","pages":"Article 103203"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-03DOI: 10.1016/j.astropartphys.2026.103204
Rajat Shinde , Julia Djuvsland , Davide Depaoli , Jim Hinton
Heavy Weakly Interacting Massive Particles (WIMPs) remain a prominent yet less constrained dark matter (DM) candidate, with the Galactic Centre (GC) serving as a prime target for indirect detection via gamma-ray signals. Extending our previous work that highlighted the significance of secondary inverse Compton (IC) emission from annihilation-produced electrons, we expand the analysis to a broader range of WIMP masses and introduce a more realistic spatially-dependent modelling framework for the GC environment. This approach incorporates complexities such as the three-dimensional DM distribution, spatially varying radiation and magnetic fields, and electron transport mechanisms like Galactic winds and diffusion. We assess the impact of these environmental factors on both the spatial and spectral characteristics of the resulting secondary emissions. Our results demonstrate the robustness and necessity of incorporating this emission, and highlight its role in enhancing the prospects for detecting heavy WIMPs through observations of the inner Galaxy. We provide the resulting data products to the community to support future analyses and observational studies.
{"title":"A refined model of secondary photon emission from heavy WIMP annihilations in the Galactic Centre","authors":"Rajat Shinde , Julia Djuvsland , Davide Depaoli , Jim Hinton","doi":"10.1016/j.astropartphys.2026.103204","DOIUrl":"10.1016/j.astropartphys.2026.103204","url":null,"abstract":"<div><div>Heavy Weakly Interacting Massive Particles (WIMPs) remain a prominent yet less constrained dark matter (DM) candidate, with the Galactic Centre (GC) serving as a prime target for indirect detection via gamma-ray signals. Extending our previous work that highlighted the significance of secondary inverse Compton (IC) emission from annihilation-produced electrons, we expand the analysis to a broader range of WIMP masses and introduce a more realistic spatially-dependent modelling framework for the GC environment. This approach incorporates complexities such as the three-dimensional DM distribution, spatially varying radiation and magnetic fields, and electron transport mechanisms like Galactic winds and diffusion. We assess the impact of these environmental factors on both the spatial and spectral characteristics of the resulting secondary emissions. Our results demonstrate the robustness and necessity of incorporating this emission, and highlight its role in enhancing the prospects for detecting heavy WIMPs through observations of the inner Galaxy. We provide the resulting data products to the community to support future analyses and observational studies.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"176 ","pages":"Article 103204"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-11-29DOI: 10.1016/j.astropartphys.2025.103200
A A Watson
A review of several analyses is presented that forces the conclusion that the mass composition of the highest-energy cosmic rays is not proton-dominated. This deduction, combined with the use of a modern hadronic interaction model, should lead to a re-evaluation of the energy spectrum reported by the Telescope Collaboration that may well bring that measurement, and the corresponding one from the Pierre Auger Observatory, into better agreement.
{"title":"The mass of cosmic rays of ultra-high energy","authors":"A A Watson","doi":"10.1016/j.astropartphys.2025.103200","DOIUrl":"10.1016/j.astropartphys.2025.103200","url":null,"abstract":"<div><div>A review of several analyses is presented that forces the conclusion that the mass composition of the highest-energy cosmic rays is not proton-dominated. This deduction, combined with the use of a modern hadronic interaction model, should lead to a re-evaluation of the energy spectrum reported by the Telescope Collaboration that may well bring that measurement, and the corresponding one from the Pierre Auger Observatory, into better agreement.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"176 ","pages":"Article 103200"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-10-06DOI: 10.1016/j.astropartphys.2025.103186
M. Holler , M. de Naurois , S. Panny , R. Rauth
We present a new approach for calculating the IACT detector response of high-level analyses with publicly available software based on dedicated simulations of the individual observations. For each of them, a corresponding event list is exported, paralleling the event list of the actual data. The information contained in these simulated lists can be utilized flexibly, without the need for but also being able to reduce it to the standard IRF scheme. We show that standard IRFs from simulated event lists yield consistent results, illustrating the validity of the concept. To improve on the standard response generation, we then demonstrate how to calculate the final IRFs for a given analysis geometry directly from the simulated event lists. The result is a more accurate description, where the change in IRF methodology leads to considerable differences. Finally, we introduce a new method of generating background models based on simulated event lists. By properly considering observation and detector conditions, the new approach provides an accurate description of the -like background, exhibiting good stability and a moderate systematics level.
{"title":"Utilizing simulated event lists in IACT gamma-ray astronomy","authors":"M. Holler , M. de Naurois , S. Panny , R. Rauth","doi":"10.1016/j.astropartphys.2025.103186","DOIUrl":"10.1016/j.astropartphys.2025.103186","url":null,"abstract":"<div><div>We present a new approach for calculating the IACT detector response of high-level analyses with publicly available software based on dedicated simulations of the individual observations. For each of them, a corresponding event list is exported, paralleling the event list of the actual data. The information contained in these simulated lists can be utilized flexibly, without the need for but also being able to reduce it to the standard IRF scheme. We show that standard IRFs from simulated event lists yield consistent results, illustrating the validity of the concept. To improve on the standard response generation, we then demonstrate how to calculate the final IRFs for a given analysis geometry directly from the simulated event lists. The result is a more accurate description, where the change in IRF methodology leads to considerable differences. Finally, we introduce a new method of generating background models based on simulated event lists. By properly considering observation and detector conditions, the new approach provides an accurate description of the <span><math><mi>γ</mi></math></span>-like background, exhibiting good stability and a moderate systematics level.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"175 ","pages":"Article 103186"},"PeriodicalIF":2.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-12DOI: 10.1016/j.astropartphys.2025.103172
Sebastián Mendizabal , Nicolás Viaux M. , Sebastián Tapia , Raquel Pezoa R. , Barbara Gutiérrez , Constanza Valdivieso
We present a new analytical approach to the longitudinal development of electromagnetic air showers, offering improvements to the classical Greisen formalism. We introduce a modified profile for the slope function that achieves an agreement less than 0.75% with the original for shower age parameter between , where represents the stage of shower development. Our new formalism provides an improved representation of shower evolution, particularly near and beyond the shower maximum. In addition, we propose a modified Greisen profile. Our implementation includes the zenith angle dependence on the number of particles at the detector level at high altitudes, making it particularly useful for high-altitude observatories. This expression is suitable for implementing air shower simulation tool fitting procedures over a wide range of energies and geometries. Our analysis shows that the modified Greisen profile provides better agreement with the expected evolution of particle numbers compared to the Greisen formulation when we compare it with CORSIKA simulations.
{"title":"Revisiting the longitudinal development of electromagnetic air showers: Analytical improvements to the Greisen formalism with zenith angle dependence","authors":"Sebastián Mendizabal , Nicolás Viaux M. , Sebastián Tapia , Raquel Pezoa R. , Barbara Gutiérrez , Constanza Valdivieso","doi":"10.1016/j.astropartphys.2025.103172","DOIUrl":"10.1016/j.astropartphys.2025.103172","url":null,"abstract":"<div><div>We present a new analytical approach to the longitudinal development of electromagnetic air showers, offering improvements to the classical Greisen formalism. We introduce a modified profile for the slope function <span><math><mrow><msub><mrow><mi>λ</mi></mrow><mrow><mn>1</mn></mrow></msub><mrow><mo>(</mo><mi>s</mi><mo>)</mo></mrow></mrow></math></span> that achieves an agreement less than 0.75% with the original <span><math><msub><mrow><mi>λ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> for shower age parameter <span><math><mi>s</mi></math></span> between <span><math><mrow><mn>0</mn><mo>.</mo><mn>3</mn><mo><</mo><mi>s</mi><mo><</mo><mn>1</mn><mo>.</mo><mn>4</mn></mrow></math></span>, where <span><math><mi>s</mi></math></span> represents the stage of shower development. Our new formalism provides an improved representation of shower evolution, particularly near and beyond the shower maximum. In addition, we propose a modified Greisen profile. Our implementation includes the zenith angle dependence on the number of particles at the detector level at high altitudes, making it particularly useful for high-altitude observatories. This expression is suitable for implementing air shower simulation tool fitting procedures over a wide range of energies and geometries. Our analysis shows that the modified Greisen profile provides better agreement with the expected evolution of particle numbers compared to the Greisen formulation when we compare it with CORSIKA simulations.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"175 ","pages":"Article 103172"},"PeriodicalIF":2.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145061193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-22DOI: 10.1016/j.astropartphys.2025.103192
Gaetano Di Marco , Rafael Alves Batista , Miguel A. Sánchez-Conde
High center-of-mass electromagnetic (EM) interactions could produce decaying heavy leptons and hadrons, leading to neutrino generation. These processes might occur in the most extreme astrophysical scenarios, potentially altering the expected gamma-ray and neutrino fluxes in both the hadronic and the leptonic pictures. For instance, neutrinos could arise from high-redshift EM cascades, triggered by gamma rays beyond scattering background photons, from radio to ultraviolet energy bands. Such energetic gamma rays are predicted in cosmogenic models and in scenarios involving non-standard physics. On astrophysical scales, leptonic production of neutrinos could take place in active galactic nuclei cores, where several-TeV gamma rays interact with the X-ray photons from the hot corona. We explore these scenarios within the CRPropa Monte Carlo code framework, developing dedicated tools to account for leptonic production and decay of heavy leptons and hadrons. In particular, the latter are performed by interfacing with the PYTHIA event generator. With these novel tools, we characterise the spectrum and flavour composition of neutrinos emerging from cosmological EM cascades and from leptonic processes in the core of active galactic nuclei. Finally, we investigate the leptonic production of neutrinos in the context of the IceCube detection of NGC 1068.
{"title":"Gamma rays as leptonic portals to energetic neutrinos: A new Monte Carlo approach","authors":"Gaetano Di Marco , Rafael Alves Batista , Miguel A. Sánchez-Conde","doi":"10.1016/j.astropartphys.2025.103192","DOIUrl":"10.1016/j.astropartphys.2025.103192","url":null,"abstract":"<div><div>High center-of-mass electromagnetic (EM) interactions could produce decaying heavy leptons and hadrons, leading to neutrino generation. These processes might occur in the most extreme astrophysical scenarios, potentially altering the expected gamma-ray and neutrino fluxes in both the hadronic and the leptonic pictures. For instance, neutrinos could arise from high-redshift EM cascades, triggered by gamma rays beyond <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>18</mn></mrow></msup><mspace></mspace><mtext>eV</mtext></mrow></math></span> scattering background photons, from radio to ultraviolet energy bands. Such energetic gamma rays are predicted in cosmogenic models and in scenarios involving non-standard physics. On astrophysical scales, leptonic production of neutrinos could take place in active galactic nuclei cores, where several-TeV gamma rays interact with the X-ray photons from the hot corona. We explore these scenarios within the CRPropa Monte Carlo code framework, developing dedicated tools to account for leptonic production and decay of heavy leptons and hadrons. In particular, the latter are performed by interfacing with the PYTHIA event generator. With these novel tools, we characterise the spectrum and flavour composition of neutrinos emerging from cosmological EM cascades and from leptonic processes in the core of active galactic nuclei. Finally, we investigate the leptonic production of neutrinos in the context of the IceCube detection of NGC 1068.</div></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"175 ","pages":"Article 103192"},"PeriodicalIF":2.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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