1. Combined fit of spectrum and composition for FR0 radio-galaxy-emitted ultra–high energy cosmic rays with resulting secondary photons and neutrinosJon Paul Lundquist, Serguei Vorobiov, Lukas Merten, Anita Reimer, Margot Boughelilba, Paolo Da Vela, Fabrizio Tavecchio, Giacomo Bonnoli, Chiara Righi, 2025, original scientific article Abstract: This study comprehensively investigates the gamma-ray dim population of Fanaroff–Riley
Type 0 (FR0) radio galaxies as potentially significant sources of ultra–high energy cosmic rays
(UHECRs, E > 10[sup]18 eV) detected on Earth. While individual FR0 luminosities are relatively
low compared to the more powerful Fanaroff–Riley Type 1 and Type 2 galaxies, FR0s are
substantially more prevalent in the local universe, outnumbering the more energetic galaxies
by a factor of ∼5 within a redshift of z ≤ 0.05. Employing CRPropa3 simulations, we estimate
the mass composition and energy spectra of UHECRs originating from FR0 galaxies for energies
above 10[sup]18.6 eV. This estimation fits data from the Pierre Auger Observatory (Auger)
using three extensive air shower models; both constant and energy-dependent observed
elemental fractions are considered. The simulation integrates an approximately isotropic
distribution of FR0 galaxies, extrapolated from observed characteristics, with UHECR
propagation in the intergalactic medium, incorporating various plausible configurations of
extragalactic magnetic fields, both random and structured. We then compare the resulting
emission spectral indices, rigidity cutoffs, and elemental fractions with recent Auger results.
In total, 25 combined energy-spectrum and mass-composition fits are considered. Beyond
the cosmic-ray fluxes emitted by FR0 galaxies, this study predicts the secondary photon and
neutrino fluxes from UHECR interactions with intergalactic cosmic photon backgrounds.
The multimessenger approach, encompassing observational data and theoretical models,
helps elucidate the contribution of low-luminosity FR0 radio galaxies to the total cosmic-ray
energy density. Keywords: ultra-high-energy cosmic rays, UHECRs, UHECR energy spectrum, Pierre Auger Observatory, UHECR mass composition, UHECR sources, extragalactic magnetic fields, UHECR propagation, CRPropa tool Published in RUNG: 06.01.2025; Views: 323; Downloads: 6
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2. Chemical interactions at the interface of Au on ▫$Bi_2 Se_3$▫ topological insulatorMatjaž Valant, Sandra Gardonio, Saul Estandia, Mattia Fanetti, Andrey Vladimirovich Matetskiy, Polina M. Sheverdyaeva, Paolo Moras, Vasiliki Tileli, 2024, original scientific article Published in RUNG: 01.10.2024; Views: 650; Downloads: 4
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3. Single crystal synthesis and surface electronic structure of Bi_{1.993}Cr_{0.007}Se_{3}Sandra Gardonio, Zipporah Rini Benher, Mattia Fanetti, Paolo Moras, Polina M. Sheverdyaeva, Matjaž Valant, 2024, original scientific article Keywords: topological insulators, magnetic atoms, crystal synthesis, formation of clusters, surface electronic structure Published in RUNG: 21.08.2024; Views: 997; Downloads: 8
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4. Tunable emissive ▫$CsPbBr_3 /Cs_4PbBr_6$▫ quantum dots engineered by discrete phase transformation for enhanced photogating in field-effect phototransistorsHan Xiao, Siyuan Wan, Lin He, Junlong Zou, Andraž Mavrič, Yixi Wang, Marek Piotrowski, Anil Kumar Bandela, Paolo Samorì, Zhiming M. Wang, 2024, original scientific article Abstract: Precise control of quantum structures in hybrid nanocrystals requires advancements in scientific methodologies. Here, on the design of tunable CsPbBr3/Cs4PbBr6 quantum dots are reported by developing a unique discrete phase transformation approach in Cs4PbBr6 nanocrystals. Unlike conventional hybrid systems that emit solely in the green region, this current strategy produces adjustable luminescence in the blue (450 nm), cyan (480 nm), and green (510 nm) regions with high photoluminescence quantum yields up to 45%, 60%, and 85%, respectively. Concentration‐dependent studies reveal that phase transformation mechanisms and the factors that drive CsBr removal occur at lower dilutions while the dissolution–recrystallization process dominates at higher dilutions. When the polymer‐CsPbBr3/Cs4PbBr6 integrated into a field‐effected transistor the resulting phototransistors featured enhanced photosensitivity exceeding 105, being the highest reported for an n‐type phototransistor, while maintaining good transistor performances as compared to devices consisting of polymer‐CsPbBr3 NCs. Keywords: crystallization mechanisms, dilution-induced kinetic trapping, photogating effect, phototransistors, quantum dots Published in RUNG: 26.06.2024; Views: 1182; Downloads: 11
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5. Changes in black carbon emissions over Europe due to COVID-19 lockdownsNikolaos Evangeliou, Stephen M. Platt, Sabine Eckhardt, Cathrine Lund Myhre, Paolo Laj, Lucas Alados-Arboledas, John Backman, Benjamin T. Brem, Markus Fiebig, Jesús Yus-Díez, 2021, original scientific article Abstract: Abstract. Following the emergence of the severe acute respiratory syndrome coronavirus
2 (SARS-CoV-2) responsible for COVID-19 in December 2019 in Wuhan (China)
and its spread to the rest of the world, the World Health Organization
declared a global pandemic in March 2020. Without effective treatment in the
initial pandemic phase, social distancing and mandatory quarantines were
introduced as the only available preventative measure. In contrast to the
detrimental societal impacts, air quality improved in all countries in which
strict lockdowns were applied, due to lower pollutant emissions. Here we
investigate the effects of the COVID-19 lockdowns in Europe on ambient black
carbon (BC), which affects climate and damages health, using in situ
observations from 17 European stations in a Bayesian inversion framework. BC
emissions declined by 23 kt in Europe (20 % in Italy, 40 % in Germany,
34 % in Spain, 22 % in France) during lockdowns compared to the same
period in the previous 5 years, which is partially attributed to COVID-19
measures. BC temporal variation in the countries enduring the most drastic
restrictions showed the most distinct lockdown impacts. Increased particle
light absorption in the beginning of the lockdown, confirmed by assimilated
satellite and remote sensing data, suggests residential combustion was the
dominant BC source. Accordingly, in central and Eastern Europe, which
experienced lower than average temperatures, BC was elevated compared to the
previous 5 years. Nevertheless, an average decrease of 11 % was seen
for the whole of Europe compared to the start of the lockdown period, with
the highest peaks in France (42 %), Germany (21 %), UK (13 %), Spain
(11 %) and Italy (8 %). Such a decrease was not seen in the previous
years, which also confirms the impact of COVID-19 on the European emissions
of BC. Keywords: black carbon, covid-19, emissions, Europe Published in RUNG: 13.05.2024; Views: 2034; Downloads: 6
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6. Applicability of benchtop multi-wavelength polar photometers to off-line measurements of the Multi-Angle Absorption Photometer (MAAP) samplesSara Valentini, Vera Bernardoni, Ezio Bolzacchini, Davide Ciniglia, Luca Ferrero, Alice Corina Forello, Dario Massabò, Marco Pandolfi, Paolo Prati, Jesús Yus-Díez, 2021, original scientific article Keywords: aerosol absorption coefficient, equivalent black carbon, MAAP, polar photometer, multi-wavelength Published in RUNG: 13.05.2024; Views: 1149; Downloads: 2
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7. Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observationsMarjan Savadkoohi, Marco Pandolfi, Olivier Favez, Jean-Philippe Putaud, Konstantinos Eleftheriadis, Markus Fiebig, Philip Hopke, Paolo Laj, A. Wiedensohler, Griša Močnik, 2024, original scientific article Abstract: A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial–temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling regression MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2/g from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2/g from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasizes the necessity of incorporating EC observations to constrain the uncertainty associated with eBC. Keywords: equivalent black carbon, mass absorption cross-section, filter absorption photometers, elemental carbon, absorption, site specific MAC, rolling MAC Published in RUNG: 04.03.2024; Views: 1820; Downloads: 10
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8. Investigation of multi-messenger properties of FR0 radio galaxy emitted ultra-high energy cosmic raysJon Paul Lundquist, Lukas Merten, Serguei Vorobiov, Margot Boughelilba, Albert Reimer, Paolo Da Vela, F. Tavecchio, G. Bonnoli, C. Righi, 2023, published scientific conference contribution Abstract: Low luminosity Fanaroff-Riley type 0 (FR0) radio galaxies are amongst potential contributors to the observed flux of ultra-high energy cosmic rays (UHECRs). Due to FR0s’ much higher abundance in the local universe than more powerful radio galaxies (e.g., about five times more ubiquitous at redshifts z≤0.05 than FR1s), they could provide a substantial fraction of the total UHECR energy density.
In the presented work, we determine the mass composition and energy spectrum of UHECRs emitted by FR0 sources by fitting simulation results from the CRPropa3 framework to the recently published Pierre Auger Observatory data. The resulting emission spectral characteristics (spectral indices, rigidity cutoffs) and elemental group fractions are compared to the Auger results. The FR0 simulations include the approximately isotropic distribution of FR0s extrapolated from the measured FR0 galaxy properties and various extragalactic magnetic field configurations, including random and large-scale structured fields. We predict the fluxes of secondary photons and neutrinos produced during UHECR propagation through cosmic photon backgrounds. The presented results allow for probing the properties of the FR0 radio galaxies as cosmic-ray sources using observational high-energy multi-messenger data. Keywords: ultra-high energy cosmic rays, UHECRs, Pierre Auger Observatory, UHECR propagation, UHECR interactions, UHECR energy spectrum, UHECR mass composition, UHECR sources, Fanaroff-Riley (FR) radio galaxies, FR0 galaxies Published in RUNG: 24.01.2024; Views: 1835; Downloads: 46
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9. Low-luminosity jetted AGN as particle multi-messenger sourcesAnita Reimer, Margot Boughelilba, Lukas Merten, Paolo Da Vela, Jon Paul Lundquist, Serguei Vorobiov, 2023, published scientific conference contribution abstract Abstract: The detection of cosmic gamma rays, high-energy neutrinos and cosmic rays (CRs) signal the existence of environments in the Universe that allow particle acceleration to extremely high energies. These observable signatures from putative CR sources are the result of in-source acceleration of particles, their energy and time-dependent transport including interactions in an evolving environment and their escape from source, in addition to source-to-Earth propagation.
Low-luminosity AGN jets constitute the most abundant persistent jet source population in the local Universe. The dominant subset of these, Fanaroff-Riley 0 (FR0) galaxies, have recently been proposed as sources contributing to the ultra-high-energy cosmic ray (UHECR) flux observed on Earth. This presentation assesses the survival, workings and multi-messenger signatures of UHECRs in low-luminosity jet environments, with focus on FR0 galaxies. For this purpose we use our recently developed, fully time-dependent CR particle and photon propagation framework which takes into account all relevant secondary production and energy loss processes, allows for an evolving source environment and efficient treatment of transport non-linearities due to the produced particles/photons being fed back into the simulation chain.
Finally, we propagate UHE cosmic-ray nuclei and secondary cosmogenic photons and neutrinos from FR0 galaxies to Earth for several extragalactic magnetic field scenarios using the CRPropa3 framework, and confront the resulting energy spectra and composition on Earth with the current observational situation. Keywords: multi-messenger astrophysics, ultra-high-energy cosmic rays, very-high-energy gamma-rays Published in RUNG: 13.09.2023; Views: 2214; Downloads: 8
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10. The UHECR-FR0 radio galaxy connection : a multi-messenger study of energy spectra/composition emission and intergalactic magnetic field propagationJon Paul Lundquist, Lukas Merten, Serguei Vorobiov, Margot Boughelilba, Anita Reimer, Paolo Da Vela, Fabrizio Tavecchio, Giacomo Bonnoli, Chiara Righi, 2023, published scientific conference contribution Abstract: This study investigates low luminosity Fanaroff-Riley Type 0 (FR0) radio galaxies as a potentially
significant source of ultra-high energy cosmic rays (UHECRs). Due to their much higher prevalence
in the local universe compared to more powerful radio galaxies (about five times more than
FR-1s), FR0s may provide a substantial fraction of the total UHECR energy density. To determine
the nucleon composition and energy spectrum of UHECRs emitted by FR0 sources, simulation
results from CRPropa3 are fit to Pierre Auger Observatory data. The resulting emission spectral
indices, rigidity cutoffs, and nucleon fractions are compared to recent Auger results. The FR0 simulations
include the approximately isotropic distribution of FR0 galaxies and various intergalactic
magnetic field configurations (including random and structured fields) and predict the fluxes of
secondary photons and neutrinos produced during UHECR propagation through cosmic photon
backgrounds. This comprehensive simulation allows for investigating the properties of the FR0
sources using observational multi-messenger data. Keywords: ultra-high energy cosmic rays, UHECR propagation, CRPropa, active galactic nuclei, jetted AGN, FR0 radio galaxies, Pierre Auger Observatory, UHECR energy spectrum Published in RUNG: 24.08.2023; Views: 2102; Downloads: 5
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