Research Articles (Physics)

Permanent URI for this collectionhttp://hdl.handle.net/2263/1725

A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from
the Department of Physics

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Visible-light driven photocatalytic degradation of tartrazine using Co@ZIF-8 monoliths
Tshuma, Piwai; Phiri, Arnold; Chaparadza, Mercy; Seimela, Thapelo Ephraim; Diale, M. (Mmantsae Moche); Poshayi, Nicola Vimbainashe; Marazani, Linia Gedi; Mehlana, Gift (Royal Society of Chemistry, 2026-08-12)
Please read abstract in the article.
Objective clustering protocol for single-molecule data : a lifetime vs. intensity study
Lovemore, Michael Andrew Charles; Van Heerden, Bertus; Botha, Joshua Leon; Kruger, T.P.J. (Tjaart) (Elsevier, 2026-06-10)
Single-molecule spectroscopy (SMS) is an exceptionally sensitive technique, but its inherently limited photon budget produces noisy data that can readily lead to subjective analyses, fitting errors, and reduced statistical power, obscuring true subpopulations and their dynamics. Here, we present an unbiased, objective method to cluster two-dimensional single-molecule data and demonstrate it on fluorescence lifetime-intensity correlations. The clustering method is based on Gaussian mixture modeling, with the optimal number of clusters determined through information criteria (the Akaike and Bayesian information criteria and integrated completed likelihood) and supplemented by cluster-quality metrics such as average cluster tightness and the fraction of points outside confidence ellipses, which guide the selection of statistically robust and physically meaningful clusters. The protocol was benchmarked on simulated datasets spanning clean, smeared, and noisy overlap-limited regimes and applied to experimental data from Alexa Fluor 647 and QD605. This approach reliably recovers relevant subpopulations even in the presence of noise and overlapping distributions, providing an objective framework for analyzing single-molecule heterogeneity, with limitations arising primarily under severe geometric overlap or extreme state-occupancy imbalance where distinct populations are no longer separable.
Size-dependent fluorescence kinetics reveal contributions of intrinsic quenching and singlet–triplet annihilation during LHCII aggregation
Conradie, Francois; Van Heerden, Bertus; Gwizdala, Michal; Kruger, T.P.J. (Tjaart) (Elsevier, 2026-11-01)
Aggregation of the main antenna complex of higher plants, Light-Harvesting Complex II (LHCII), is widely used as an in-vitro model for energy-dependent quenching (qE), yet fluorescence reduction in aggregates is frequently interpreted without a quantitative separation of intrinsic quenching from excitation-induced annihilation. Here, we address this ambiguity by directly correlating aggregate size, concentration, steady-state fluorescence intensity, and decay kinetics during controlled, incremental aggregation of isolated LHCII. By combining fluorescence correlation spectroscopy (FCS) with time-correlated single-photon counting (TCSPC) in a unified experimental framework, we monitored structural and photophysical changes in real time as detergent removal drives biphasic aggregation. We quantified the aggregate composition from the particle concentrations, enabling direct scaling of the absorption cross-section with aggregate size. The average fluorescence lifetime decreased semi-logarithmically with increases in hydrodynamic radius, whereas steady-state fluorescence intensities deviated strongly from this trend. Intensity-dependent measurements and steady-state kinetic modeling reveal that singlet-triplet annihilation (STA) emerges at moderate excitation intensities and rapidly becomes the dominant contributor to fluorescence quenching, even for relatively small aggregates. In contrast, intrinsic quenching increases more gradually with aggregate size. By quantitatively disentangling intrinsic excitation quenching from annihilation processes, this work demonstrates that STA can govern the apparent photophysical response of aggregated LHCII across excitation regimes commonly considered non-annihilating. The size-dependent mechanistic framework presented here provides a basis for distinguishing intrinsic quenching from annihilation effects in aggregation-based studies of photosynthetic antenna complexes. HIGHLIGHTS • TCSPC-FCS uncovers biphasic LHCII aggregation during detergent removal. • Average LHCII aggregate compositions can be estimated from relative particle concentrations. • Excitation quenching depends logarithmically on LHCII aggregate size. • LHCII aggregation dramatically increases singlet-triplet annihilation. • Quenching and annihilation in LHCII aggregates can be disentangled by incremental aggregation.
Synergetic properties of advanced materials for high-power and high-temperature applications
Mengesha, Wubshet Getachew; Nagessar, Kaveer (Springer Nature, 2026-04-10)
This paper explores the advancements, applications, and challenges of advanced thermal and magnetic materials in high-power and high-temperature environments. These materials, including high-temperature superconductors, ferromagnetic materials, and magnetic alloys, are crucial for industries such as energy, aerospace, automotive, and electronics. They are crucial for managing heat, converting energy, and storing it, which boosts the efficiency and dependability of renewable energy systems, electric vehicles, and aerospace technologies. Nonetheless, they encounter major obstacles, such as material breakdown under harsh conditions, expensive production, and sustain- ability issues. The study explores essential thermal properties like heat capacity, thermal conductivity, thermal expansion, and thermal stress, highlighting the significance of ceramics, composites, metals, carbon nanotubes, and phase-change materials. It also investigates magnetic properties like permeability, coercivity, and remanence, essential for high-power applications. Emerging technologies such as nanotechnology, additive manufacturing, and machine learning offer promising solutions to overcome existing limitations. The review highlights the need for interdisciplinary research to develop sustainable and cost-effective materials capable of withstanding extreme conditions while maintaining performance. It underscores the importance of continuing research and development to address global energy and environmental challenges, paving the way for next-generation technologies. In summary, cutting-edge thermal and magnetic materials are set to transform industries, paving the way for more efficient and dependable technological advancements.
Enhanced performance of PTB7-Th:PCBM-based organic solar cells via broadening of localized surface plasmon resonance
Mulat, Simenew A.; Hamed, Mohamed S.G.; Hone, Fekadu G.; Nchinda, Leonato Tambua; Gelderblom, Elizabeth M.; Diale, M. (Mmantsae Moche); Kruger, T.P.J. (Tjaart); Bekri, Nika; Tegegne, Newayemedhin A. (Royal Society of Chemistry, 2026-07)
Please read abstract in the article.
Dual plasmonic effects for performance enhancementof PBDD4T-based organic solar cells
Mulat, Simenew A.; Nchinda, Leonato Tambua; Hamed, Mohamed S.G.; Seimela, Thapelo Ephraim; Hone, Fekadu G.; Diale, M. (Mmantsae Moche); Kruger, T.P.J. (Tjaart); Bekri, Nika; Tegegne, Newayemedhin A. (American Chemical Society, 2026-07)
Limited light absorption constrains the power conversion efficiency of thin-film organic solar cells (OSCs). Plasmonic nanoparticles offer an effective strategy for enhancing light trapping without increasing absorber thickness. In this work, mixed cubic and ellipsoidal colloidal Cu nanoparticles (c-Cu NPs) were incorporated into the ZnO electron transport layer (ETL) of inverted PBDD4T:PC71BM-based OSCs at volume ratios of 0, 0.25, 0.5, and 1% to exploit their dual plasmonic response. An optimal loading of 0.5% c-Cu NPs increased the PCE from 5.05% in the pristine device to 9.11%, representing an improvement of over 80% through simultaneous enhancements in the open-circuit voltage, short-circuit current density, and fill factor. The external quantum efficiency was enhanced by more than 50%, which is attributed to the broadband localized surface plasmon resonance of mixed-shaped Cu nanoparticles, resulting from near-field enhancement and forward scattering effects. The overall performance improvement is ascribed to the synergistic enhancement of charge generation, carrier mobility, and charge collection. Furthermore, the reduced defect density and smoother morphology of the c-Cu NPs–embedded ZnO ETL facilitate more efficient charge transfer and collection in the devices.
Assessment of nuclear energy potential of South Africa's uranium production and resources
Kenan, A.O.; Hlatshwayo, Thulani Thokozani; Hlatshwayo, S.M. (Elsevier, 2026-10)
The degree to which uranium resources and production in South Africa can support nuclear power generation under practical fuel-cycle circumstances is discussed in this work. Through enrichment level, tails assay, discharge burnup, thermal efficiency, and capacity factor, a stochastic modelling framework is created to link uranium availability to reactor-level fuel requirements. To capture parameter uncertainty for representative production years (1980, 2007, 2020, 2023) and resource years (2014, 2016, 2023), Monte Carlo simulations using Latin hypercube sampling were run with 4000 realisations per scenario, which convergence diagnostics revealed that increasing the sample size beyond 4000 realisations resulted in negligible changes to correlation estimates and output distributions. Using bootstrap resampling and Spearman and partial-rank correlation coefficients, sensitivity was assessed. According to the results, over 200 small modular reactors (~0.15 GWe each) or about thirty Koeberg-scale pressurized-water reactors (~1 GWe each) could have maintained about 33 GWe of continuous generating capacity at the 1980 production output peak. On the other hand, just 1.3 GWe can be produced at the 2023 production level. The theoretical nuclear-electric capacity supported by reported uranium resources decreased from approximately 2400 GWe in 2014 and 2016 to approximately 878 GWe in 2023. This decline is the result of economic reclassification driven by low uranium prices and deeper mining costs, and not because of depletion of uranium in-situ tonnages. The specific enrichment requirement remained relatively constant at approximately 142 t SWU per GWe across all scenarios. These results show that uranium resource in South Africa is still sufficient to support nuclear growth even with decreased production, provided that market, policy, and infrastructure conditions improve. Restoring specific front-end fuel-cycle capabilities (fuel manufacturing, enrichment partnerships, and conversion) could improve national energy security and mitigate energy shortages in South Africa. Unlike prior OECD-NEA and IAEA Red Book assessments that use static consumption ratios, this study provides a probabilistic, physics-based linkage of uranium production and resources to potential GWe output, identifying SWU invariance as a key planning insight. HIGHLIGHTS • South Africa's uranium resources could theoretically support 878 GWe-years of operation. • Current production (233 t U in 2023) would fuel only ~1.3 GWe, a > 95% decline since 1980. • SWU requirement per GWe is invariant (~142 t SWU/GWe), independent of production scale. • Fuel burnup is the most sensitive parameter controlling uranium utilisation efficiency. • Re-establishing fuel-cycle localisation could capture ~90% of current value lost to exports.
Design of bimetallic NiCo-MOFs via dual-ligand strategy for enhanced supercapacitor performance
Diop, Ndeye Fatou; Otun, Kabir Opeyemi; Sylla, Ndeye Fatou; Maphiri, Vusani Muswa; Thior, Souleymane; Kitenge, Vianney Ngoyi; Rutavi, Gift; Ndiaye, Ndeye Maty; Ngom, Balla D.; Manyala, Ncholu I. (Elsevier, 2026-10-10)
In electrochemical capacitors, metal-organic frameworks (MOFs) have attracted increasing attention due to their fascinating organic-inorganic structures and remarkable properties, including high specific surface area, tunable porosity, and variable chemical functionality. In this study, two bimetallic nickel-cobalt metal-organic frameworks (NiCo-MOFs) were synthesized via a one-step precipitation method using different ligand strategies: A single-ligand approach employing only 2-methylimidazole (1L-NiCo-MOF), and a dual-ligand approach combining 2-methylimidazole with 1,3,5-benzene tricarboxylic acid (2L-NiCo-MOF). The incorporation of both ligands provides abundant active redox nickel and cobalt metal centers that are accessible for an efficient supercapacitor. Moreover, Raman, XRD, FTIR, BET, AFM and SEM were used to study the functional groups, crystallinity, porosity, and morphology present in the single and double-ligand NiCo-MOF. Electrochemically, the 2L-NiCo-MOF delivered along with fast kinetics, high reversibility, and excellent specific capacity of 137 mAh g⁻¹ at 1 A g⁻¹ and exhibited a good capacity retention of 86.8 % over 5,000 cycles. An asymmetric supercapacitor device (2L-NiCo-MOF//AC) fabricated using dual-ligand NiCo-MOF as the positive electrode and peanut shell activated carbon (AC) as the negative electrode achieved a specific capacity of 61.3 mAh g⁻¹ at 0.5 A g⁻¹, corresponding to a specific energy and specific power of 38.1 Wh kg⁻¹ and 612 W kg⁻¹, respectively, and a maximum power density of 401 kW kg⁻¹. These results demonstrate that the dual-ligand strategy effectively engineers pore architecture and surface morphology compared to the one ligand, yielding promising electrode materials for high-performance asymmetric supercapacitors. HIGHLIGHTS • Mixed metal ions revealed synergistic enhancement effects. • NiCo-MOFs single and dual-ligands were synthesis at room temperature via precipitation methods. • Bimetallic rhombohedral change to polyhedral-like structures. • Dual-ligand NiCo metal-organic framework exhibited a high specific capacity and high stability for better energy storage.
The persistent shadow of the supermassive black hole of M87 : II. Model comparisons and theoretical interpretations
Akiyama, Kazunori; Albentosa-Ruíz, Ezequiel; Alberdi, Antxon; Alef, Walter; Algaba, Juan Carlos; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Bach, Uwe; Baczko, Anne-Kathrin; Ball, David; Balokovic, Mislav; Bandyopadhyay, Bidisha; Barrett, John; Bauböck, Michi; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Bouman, Katherine L.; Bower, Geoffrey C.; Bremer, Michael; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Bustamante, Sandra; Carlstrom, John E.; Chael, Andrew; Chan, Chi-kwan; Chang, Dominic O.; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-Tang; Chen, Yongjun; Cheng, Xiaopeng; Cho, Ilje; Christian, Pierre; Conroy, Nicholas S.; Conway, John E.; Crawford1, Thomas M.; Crew, Geoffrey B.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Curd, Brandon; Dahale, Rohan; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Dhruv, Vedant; Dihingia, Indu K.; Doeleman, Sheperd S.; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Edward; Ford, H. Alyson; Foschi, Marianna; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Goddi, Ciriaco; Gold, Roman; Gómez-Ruiz, Arturo I.; Gómez, José L.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hesper, Ronald; Heumann, Dirk; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Impellizzeri, C.M. Violette; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jiménez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jones, Adam C.; Joshi, Abhishek V.; Jung, Taehyun; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kocherlakota, Prashant; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Carsten; Kramer, Joana A.; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; La Bella, Noemi; Lee, Sang-Sung; Levis, Aviad; Li, Zhiyuan; Lico, Rocco; Lindahl, Greg; Lindqvist, Michael; Lisakov, Mikhail; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Marko, Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Montgomery, Joshua Montgomery; Moran, James M.; Moriyama, Kotaro; Moscibrodzka, Monika; Mulaudzi, Wanga; Müller, Cornelia; Müller, Hendrik; Mus, Alejandro; Musoke, Gibwa; Myserlis, Ioannis; Nagai, Hiroshi; Nagar, Neil M.; Nair, Dhanya G.; Nakamura, Masanori; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Navarro Fuentes, Santiago; Neilsen, Joey; Ni, Chunchong; Nowak, Michael A.; Oh, Junghwan; Okino, Hiroki; Olivares Sánchez, Héctor Raúl; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C.M.; Paraschos, Georgios Filippos; Park, Jongho; Parsons, Harriet; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; PopStefanija, Aleksandar; Porth, Oliver; Prather, Ben; Principe, Giacomo; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Rezzolla, Luciano; Ricarte, Angelo; Ripperda, Bart; Roelofs, Freek; Romero-Cañizales, Cristina; Ros, Eduardo; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Rygl, Kazi L.J.; Sánchez, Salvador; Sánchez-Argüelles, David; Sánchez-Portal, Miguel; Sasada, Mahito; Satapathy, Kaushik; Savolainen, Tuomas; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Small, Des; Sohn, Bong Won; SooHoo, Jason; Salas, León D.S.; Souccar, Kamal; Stanway, Joshua S.; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus, Remo P.J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Toscano, Teresa; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; Turk, Matthew; Van Bemmel, Ilse; Van Langevelde, Huib Jan; Van Rossum, Daniel R.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Washington, Jasmin E.; Weintroub, Jonathan; Wharton, Robert; Wielgus, Maciek; Witzel, Gunther; Wiik, Kaj; Wondrak, Michael F.; Wong, George N.; Wu, Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis, Aristomenis; Yoon, Doosoo; Young, André; Younsi, Ziri; Yu, Wei; Yuan, Feng; Yuan, Ye-Fei; Zensus, J. Anton; Zhang, Shuo; Zhao, Guang-Yao; Zhao, Shan-Shan (EDP Sciences, 2025-01)
The Event Horizon Telescope (EHT) observation of M87 in 2018 has revealed a ring with a diameter that is consistent with the 2017 observation. The brightest part of the ring is shifted to the southwest from the southeast. In this paper, we provide theoretical interpretations for the multi-epoch EHT observations for M87 by comparing a new general relativistic magnetohydrodynamics model image library with the EHT observations for M87 in both 2017 and 2018. The model images include aligned and tilted accretion with parameterized thermal and nonthermal synchrotron emission properties. The 2018 observation again shows that the spin vector of the M87 supermassive black hole is pointed away from Earth. A shift of the brightest part of the ring during the multi-epoch observations can naturally be explained by the turbulent nature of black hole accretion, which is supported by the fact that the more turbulent retrograde models can explain the multi-epoch observations better than the prograde models. The EHT data are inconsistent with the tilted models in our model image library. Assuming that the black hole spin axis and its large-scale jet direction are roughly aligned, we expect the brightest part of the ring to be most commonly observed 90 deg clockwise from the forward jet. This prediction can be statistically tested through future observations.
Origin of the ring ellipticity in the black hole images of M87*
Dahale , Rohan; Cho, Ilje; Moriyama, Kotaro; Wiik, Kaj; Tiede, Paul; Gómez, José L.; Chan, Chi-kwan; Gold, Roman; Bernshteyn , Vadim Y.; Foschi, Marianna; Jeter, Britton; Pu, Hung-Yi; Georgiev, Boris; Joshi, Abhishek V.; Cruz-Osorio, Alejandro; Natarajan, Iniyan; Broderick, Avery E.; Salas, León D.S.; Chatterjee, Koushik; Akiyama, Kazunori; Albentosa-Ruíz, Ezequiel; Alberdi , Antxon; Alef, Walter; Algaba, Juan Carlos; Anantua, Richard; Asada, Keiichi; Azulay , Rebecca; Bach, Uwe; Baczko, Anne-Kathrin; David , Ball; Balokovi´c, Mislav; Bandyopadhyay, Bidisha; Barrett, John; Bauböck, Michi; Benson , Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Bouman, Katherine L.; Bower, Geoffrey C.; Bremer, Michael; Brissenden, Roger; Britzen, Silke; Broguiere, Dominique; Bronzwaer, Thomas; Bustamante, Sandra; Carlos, Douglas Ferreira; Carlstrom, John E.; Chael, Andrew; Chang, Dominic O.; Chatterjee, Shami; Chen, Ming-Tang; Chen, Yongjun; Cheng, Xiaopeng; Christian, Pierre; Conroy, Nicholas S.; Conway, John E.; Crawford , Thomas M.; Crew, Geoffrey B.; Cui, Yuzhu; Curd, Brandon; Davelaar, Jordy; De Laurentis , Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Vedant Dhruv, Vedant; Dihingia, Indu K.; Doeleman , Sheperd S.; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Edward; Ford , H. Alyson; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz , Olivier; Geertsema, Gertie; Goddi , Ciriaco; Gómez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hesper, Ronald; Heumann , Dirk; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda , Shiro; Impellizzeri, C.M. Violette; Inoue, Makoto; Issaoun , Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jiang, Wu; Jiménez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jones, Adam C.; Jung, Taehyun; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis , Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Junhan; Kim, Jongsoo; Kino, Motoki; Koay , Jun Yi; Kocherlakota, Prashant; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Carsten; Kramer, Joana A.; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; La Bella , Noemi; Lee, Sang-Sung; Levis, Aviad; Li, Zhiyuan; Lico, Rocco; Lindahl, Greg; Lindqvist, Michael; Lisakov, Mikhail; Liu, Jun; Liu , Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Markoff , Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Montgomery , Joshua; Moran, James M.; Moscibrodzka, Monika; Mulaudzi, Wanga; Müller, Cornelia; Müller , Hendrik; Mus, Alejandro; Musoke , Gibwa; Myserlis, Ioannis; Nagai , Hiroshi; Nagar, Neil M.; Nair, Dhanya G.; Nakamura, Masanori; Narayanan, Gopal; Nathanail, Antonios; Navarro Fuentes, Santiago; Neilsen, Joey; Ni, Chunchong; Nowak, Michael A.; Oh , Junghwan; Okino, Hiroki; Olivares Sánchez, Héctor Raúl; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C.M.; Paraschos, Georgios Filippos; Park, Jongho; Parsons, Harriet; Nimesh, Patel; Pen , Ue-Li; Pesce, Dominic W.; Piétu, Vincent; PopStefanija, Aleksandar; Porth , Oliver; Prather, Ben; Principe, Giacomo; Psaltis, Dimitrios; Ramakrishnan, Venkatessh; Rao , Ramprasad; Rawlings, Mark G.; Rezzolla, Luciano; Ricarte, Angelo; Ripperda, Bart; Röder, Jan; Roelofs, Freek; Romero-Cañizales , Cristina; Ros, Eduardo; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Rygl, Kazi L.J.; Sánchez, Salvador; Sánchez-Argüelles, David; Sánchez-Portal, Miguel; Sasada, Mahito; Satapathy , Kaushik; Saurabh; Savolainen, Tuomas; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Silpa, Sasikumar; Small, Des; Sohn, Bong Won; SooHoo, Jason; Souccar, Kamal; Stanway, Joshua S.; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tilanus, Remo P.J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Toscano, Teresa; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; Turk, Matthew; Van Bemmel , Ilse; Van Langevelde, Huib Jan; Van Rossum , Daniel R.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Washington, Jasmin E.; Weintroub, Jonathan; Wharton, Robert; Wielgus, Maciek; Witzel, Gunther; Wondrak, Michael F.; Wong, George N.; Wu, Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis , Aristomenis; Yoon, Doosoo; Young, André; Younsi, Ziri; Yu, Wei; Yuan, Feng (EDP Sciences, 2025-07)
We investigate the origin of the elliptical ring structure observed in the images of the supermassive black hole M87*, aiming to disentangle contributions from gravitational, astrophysical, and imaging effects. Leveraging the enhanced capabilities of the Event Horizon Telescope (EHT)'s 2018 array, including improved (u,v)-coverage from the Greenland Telescope, we measured the ring's ellipticity using five independent imaging methods, obtaining a consistent average value of τ = 0.08−0.02+0.03 with a position angle of ξ = 50.1−7.6+6.2 degrees. To interpret this measurement, we compared it to general relativistic magnetohydrodynamic (GRMHD) simulations spanning a wide range of physical parameters including the thermal or nonthermal electron distribution function, spins, and ion-to-electron temperature ratios in both low- and high-density regions. We find no statistically significant correlation between spin and ellipticity in GRMHD images. Instead, we identify a correlation between ellipticity and the fraction of non-ring emission, particularly in nonthermal models and models with higher jet emission. These results indicate that the ellipticity measured from the M87* emission structure is consistent with that expected from simulations of turbulent accretion flows around black holes, where it is dominated by astrophysical effects rather than gravitational ones. Future high-resolution imaging, including space very long baseline interferometry and long-term monitoring, will be essential to isolate gravitational signatures from astrophysical effects.
Horizon-scale variability of M87* from 2017–2021 EHT observations
Akiyama, Kazunori; Albentosa-Ruíz, Ezequiel; Alberdi, Antxon; Alef, Walter; Algaba, Juan Carlos; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Bach, Uwe; Baczko, Anne-Kathrin; Ball, David; Balokovi´c, Mislav; Bandyopadhyay, Bidisha; Barrett, John; Bauböck, Michi; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Bouman, Katherine L.; Bower, Geffrey C.; Bremer, Michael; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Bustamante, Sandra; Carlos, Douglas F.; Carlstrom, John E.; Chael, Andrew; Chan, Chi-kwan; Chang, Dominic O.; Chavez, Erandi; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-Tang; Chen (陈永军), Yongjun; Cheng, Xiaopeng; Chichura, Paul; Cho, Ilje; Christian, Pierre; Conroy, Nicholas S.; Conway, John E.; Crawford, Thomas M.; Crew, Geffrey B.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Curd, Brandon; Dahale, Rohan; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Desvignes, Gregory; Dexter, Jason; Dhruv, Vedant; Dihingia, Indu K.; Doeleman, Sheperd S.; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Edward; Ford, H. Alyson; Foschi, Marianna; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Goddi, Ciriaco; Gold, Roman; Gómez-Ruiz, Arturo I.; Gómez, José L.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Hesper, Ronald; Heumann, Dirk; Ho, Luis C.; Ho, Paul; Hoak, Dan; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Impellizzeri, C.M. Violette; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang, Wu; Jiménez-Rosales, Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jones, Adam C.; Joshi, Abhishek V.; Jung, Taehyun; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kocherlakota, Prashant; Kofuji, Yutaro; Koch, Patrick M.; Koyama, Shoko; Kramer, Carsten; Kramer, Joana A.; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; La Bella, Noemi; Lee, Deokhyeong; Lee, Sang-Sung; Levis, Aviad; Li, Zhiyuan; Lico, Rocco; Lindahl, Greg; Lindqvist, Michael; Lisakov, Mikhail; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; Lu, Ru-Sen; MacDonald, Nicholas R.; Mao, Jirong; Marchili , Nicola; Marko, Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Montgomery, Joshua; Moran, James M.; Moriyama, Kotaro; Moscibrodzka, Monika; Mulaudzi, Wanga; Müller, Cornelia; Müller, Hendrik; Mus, Alejandro; Musoke, Gibwa; Myserlis, Ioannis; Ni, Chunchong; Nowak, Michael A.; Oh, Junghwan; Okino, Hiroki; Olivares Sánchez, Héctor Raúl; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C.M.; Paraschos, Georgios Filippos; Park, Jongho; Parsons, Harriet; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; Plavin, Alexander; PopStefanija, Aleksandar; Porth, Oliver; Prather, Ben; Principe, Giacomo; Psaltis, Dimitrios; Pu, Hung-Yi; Rahlin, Alexandra; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Rezzolla, Luciano; Ricarte, Angelo; Ricci, Luca; Ripperda, Bart; Röder , Jan; Roelofs, Freek; Romero-Cañizales, Cristina; Ros, Eduardo; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Rygl, Kazi L.J.; Salas, León D.S.; Sánchez, Salvador; Sánchez-Argüelles, David; Sánchez-Portal, Miguel; Sasada, Mahito; Satapathy, Kaushik; Saurabh; Savolainen, Tuomas; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Silpa, Sasikumar; Small, Des; Smith, Randall; Sohn, Bong Won; SooHoo, Jason; Souccar, Kamal; Stanway, Joshua S.; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus, Remo P.J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Toscano, Teresa; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; Turk, Matthew; Van Bemmel, Ilse; Van Langevelde, Huib Jan; Van Rossum, Daniel R.; Von Fellenberg, Sebastiano D.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Washington, Jasmin E.; Weintroub, Jonathan; West, Andrew T.; Wharton, Robert; Wielgus, Maciek; Wiik, Kaj; Witzel, Gunther; Wondrak, Michael F.; Wong, George N.; Wongphexhauxsorn, Jompoj; Wu, Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis, Aristomenis; Yoon, Doosoo; Young, André; Younsi, Ziri; Yu, Wei; Yuan, Feng; Yuan, Ye-Fei; Zeng, Ai-Ling; Zensus, J. Anton; Zhang, Shuo; Zhao, Guang-Yao; Zhao, Shan-Shan; Berthold, Ryan; Chang, Shu-Hao; Chilson, Ryan; Han, Chih-Chiang; Gale, David M.; Geertsema, Gertie; Hernández-Rebollar, José Luis; Huang, Yau-De; Keenan, Ryan P.; Kubo, Derek; Liu, Kuan-Yu (EDP Sciences, 2025-12-16)
We report three epochs of polarized images of M87* at 230 GHz using data from the Event Horizon Telescope (EHT) taken in 2017, 2018, and 2021. The baseline coverage of the 2021 observations is significantly improved through the addition of two new EHT stations: the 12m Kitt Peak Telescope and the Northern Extended Millimetre Array (NOEMA). All observations result in images dominated by a bright, asymmetric ring with a persistent diameter of 43:9 0:6 as, consistent with expectations for lensed synchrotron emission encircling the apparent shadow of a supermassive black hole. We find that the total intensity and linear polarization of M87* vary significantly across the three epochs. Specifically, the azimuthal brightness distribution of the total intensity images varies from year to year, as expected for a stochastic accretion flow. However, despite a gamma-ray flare erupting in M87 quasi-contemporaneously to the 2018 observations, the 2018 and 2021 images look remarkably similar. The resolved linear polarization fractions in 2018 and 2021 peak at 5%, compared to 15% in 2017. The spiral polarization pattern on the ring also varies from year to year, including a change in the electric vector position angle helicity in 2021 that could reflect changes in the magnetized accretion flow or an external Faraday screen. The improved 2021 coverage also provides the first EHT constraints on jet emission outside the ring, on scales of .1 mas. Overall, these observations provide strong proof of the reliability of the EHT images and probe the dynamic properties of the horizon-scale accretion flow surrounding M87*.
Schottky diodes based on polyaniline-graphene nanocomposites : tuning barrier characteristics through swift heavy ion irradiation
Chilukusha, Daniel C.; Mboukam, Jean J.; Maphiri, Vusani M.; Manyala, Ncholu I.; Msimanga, Mandla (Elsevier, 2026-04-01)
Current chemical and electrochemical methods lack the nanoscale control required to optimize polymer–metal interfaces for electronic applications. In this work, swift heavy ion (SHI) irradiation is employed to tune the barrier characteristics of Schottky diodes based on polyaniline–graphene nanocomposites (PANI-G NCs) and aluminum. Current density–voltage (J–V) measurements confirmed rectifying behavior in all devices. Key parameters including ideality factor (n), barrier height (Φb), and rectification ratio (γ) were extracted from semi-logarithmic J–V plots. The unirradiated PANI device showed the lowest n (3.8) and the highest γ (98.6). Incorporation of graphene and SHI exposure led to decreased γ and Φb, and increased n, attributed to interfacial inhomogeneities and oxide formation. Differential resistance (dV/dI vs. V) analysis revealed a decline in shunt resistance with fluence, making series resistance (Rs) dominant in charge transport. Cheung’s and Norde’s methods further showed that Rs decreased with fluence, indicating enhanced charge injection. The energy distribution of interface states shifted exponentially toward the valence band edge with increasing bias and dose. At higher voltages, irradiated devices transitioned from trap-limited to trap-free space-charge-limited conduction, suggesting SHI exposure promotes carrier detrapping. These results highlight the tunability of PANI-G SBDs via SHI irradiation and their potential for applications such as Schottky-type photodetectors and low-power rectifying elements in flexible optoelectronic systems. HIGHLIGHTS • Swift heavy ion (SHI) irradiation tunes Schottky diode properties in PANI-graphene nano composites. • SHI exposure reduces rectification ratio and barrier height, and increases ideality factor. • SHI lowers shunt resistance, enhances charge injection via reduced series resistance. • Irradiated devices transition from trap-limited to trap-free conduction at higher voltages. • Work demonstrates SHI-tailored PANI-G diodes for next-generation flexible optoelectronics
First polarization study of the M87 jet and active galactic nuclei at submillimeter wavelengths with ALMA
Goddi , Ciriaco; Carlos, Douglas F.; Crew, Geoffrey B.; Matthews, Lynn D.; Messias, Hugo; Mus, Alejandro; Martí-Vidal, Iván; Albentosa-Ruíz, Ezequiel; De Laurentis, Mariafelicia; Liuzzo, Elisabetta; Marchili , Nicola; Rygl, Kazi L.J.; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Algaba, Juan Carlos; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Bach , Uwe; Backzo, Anne-Kathrin; Ball, David; Balokovi´c, Mislav; Bandyopadhyay , Bidisha; Barrett, John; Bauböck, Michi; Benson, Bradford A.; Bintley, Dan; Blackburn, Lindy; Blundell, Raymond; Bouman, Katherine L.; Bower, Geoffrey C.; Bremer, Michael; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Bustamante, Sandra; Carlstrom, John E.; Chael , Andrew; Chan, Chi-kwan; Chang, Dominic O.; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-Tang; Chen (陈永军), Yongjun; Cheng, Xiaopeng; Cho, Ilje; Christian , Pierre; Conroy, Nicholas S.; Conway, John E.; Crawford, Thomas M.; Cruz-Osorio, Alejandro; Cui (崔玉竹), Yuzhu; Curd, Brandon; Dahale, Rohan; Davelaar, Jordy; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Dhruv, Vedant; Dihingia, Indu K.; Doeleman, Sheperd S.; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fish, Vincent L.; Fomalont, Edward; Ford, H. Alyson; Foschi, Marianna; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes , Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Gold, Roman; Gómez-Ruiz, Arturo I.; Gómez, José L.; Gu (顾敏峰), Minfeng; Gurwell , Mark; Hada, Kazuhiro; Haggard, Daryl; Hesper, Ronald; Heumann, Dirk; Ho (何子山), Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang (黄磊), Lei; Hughes , David H.; Ikeda, Shiro; Impellizzeri, C.M. Violette; Inoue, Makoto; Issaoun, Sara; James, David J.; Jannuzi, Buell T.; Janssen, Michael; Jeter, Britton; Jiang (江悟), Wu; Jiménez-Rosales , Alejandra; Johnson, Michael D.; Jorstad, Svetlana; Jones, Adam C.; Joshi , Abhishek V.; Jung, Taehyun; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim , Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kocherlakota , Prashant; Kofuji, Yutaro; Koyama, Shoko; Kramer , Carsten; Kramer, Joana A.; Kramer, Michael; Krichbaum, Thomas P.; Kuo, Cheng-Yu; La Bella, Noemi; Lee, Sang-Sung; Levis , Aviad; Li (李志远), Zhiyuan; Lico, Rocco; Lindahl; Lindahl, Greg; Lisakov, Mikhail; Liu (刘俊), Jun; Liu, Kuo; Lo, Wen-Ping; Lobanov, Andrei P.; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; Lu (路如森), Ru-Sen; MacDonald, Nicholas R.; Mao (毛基荣) , Jirong; Markoff, Sera; Marrone, Daniel P.; Marscher, Alan P.; Matsushita, Satoki; Medeiros, Lia; Menten, Karl M.; Mizuno, Izumi; Mizuno, Yosuke; Montgomery, Joshua; Moran, James M.; Moriyama , Kotaro; Moscibrodzka, Monika; Mulaudzi, Wanga; Müller, Cornelia; Müller, Hendrik; Musoke, Gibwa; Myserlis, Ioannis; Nagai, Hiroshi; Nagar, Neil M.; Nair, Dhanya G.; Nakamura, Masanori; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Fuentes, Santiago Navarro; Neilsen, Joey; Ni, Chunchong; Nowak, Michael A.; Oh , Junghwan; Okino , Hiroki; Olivares Sánchez, Héctor Raúl; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C.M.; Paraschos, Georgios Filippos; Park , Jongho; Parsons, Harriet; Patel, Nimesh; Pen, Ue-Li; Pesce , Dominic W.; Piétu, Vincent; PopStefanija, Aleksandar; Porth, Oliver; Prather, Ben; Principe, Giacomo; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Rezzolla, Luciano; Ricarte , Angelo; Ripperda, Bart; Roelofs , Freek; Romero-Cañizales, Cristina; Ros, Eduardo; Roshaninesha, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Sánchez, Salvador; Sánchez-Argüelles, David; Sánchez-Portal , Miguel; Sasada, Mahito; Satapathy, Kaushik; Saurabh; Savolainen, Tuomas; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen (沈志强), Zhiqiang; Sasikumar, Silpa; Small , Des; Sohn, Bong Won; SooHoo, Jason; Salas, León D.S.; Souccar , Kamal; Stanway, Joshua S.; Sun (孙赫), He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Tilanus , Remo P.J.; Titus, Michael; Toma, Kenji; Torne, Pablo; Toscano, Teresa; Traianou, Efthalia; Trent, Tyler; Trippe, Sascha; Turk, Matthew; Van Bemmel, Ilse; Van Langevelde , Huib Jan; Van Rossum, Daniel R.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Washington, Jasmin E.; Weintroub , Jonathan; Wharton, Robert; Wielgus, Maciek; Wiik, Kaj; Witzel, Gunther; Wondrak, Michael F.; Wong, George N.; Wu (吴庆文) , Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis , Aristomenis; Yoon, Doosoo; Young, André; Younsi, Ziri; Yu (于威), Wei; Yuan (袁峰), Feng; Yuan (袁业飞) , Ye-Fei; Zensus, J. Anton; Zhang, Shuo; Zhao, Guang-Yao; Zhao (赵杉杉), Shan-Shan (EDP Sciences, 2025-06-25)
AIMS : We investigated the polarization and Faraday properties of Messier 87 (M87) and seven other radio-loud active galactic nuclei (AGNs) at λ0.87 mm (345 GHz) using the Atacama Large Millimeter/submillimeter Array (ALMA). Our goal was to characterize the linear polarization (LP) fractions, measure Faraday rotation measures (RMs), and examine the magnetic field structures in the emission regions of these AGNs. METHODS : We conducted full-polarization observations as part of the ALMA Band 7 very long baseline interferometry (VLBI) commissioning during the April 2021 Event Horizon Telescope (EHT) campaign. We analyzed the LP fractions and RMs to assess the nature of Faraday screens and magnetic fields in the submillimeter emission regions. RESULTS : We find LP fractions between 1% and 17% and RMs exceeding 105 rad m−2, which are 1–2 orders of magnitude higher than typically observed at longer wavelengths (λ >3 mm). This suggests denser Faraday screens or stronger magnetic fields. Additionally, we present the first submillimeter polarized images of the M87 jet and the observed AGNs, revealing RM gradients and sign reversals in the M87 jet indicative of a kiloparsec-scale helical magnetic field structure. CONCLUSIONS : Our results provide essential constraints for calibrating, analyzing, and interpreting VLBI data from the EHT at 345 GHz, representing a critical step toward submillimeter VLBI imaging.
A multifrequency study of sub-parsec jets with the Event Horizon Telescope
Röder, Jan; Wielgus, Maciek; Lobanov, Andrei P.; Krichbaum, Thomas P.; Nair, Dhanya G.; Lee, Sang-Sung; Ros, Eduardo; Fish, Vincent L.; Blackburn, Lindy; Chan, Chi-kwan; Issaoun, Sara; Janssen, Michael; Johnson, Michael D.; Doeleman, Sheperd S.; Bower, Geffrey C.; Crew, Geffrey B.; Remo P. J. Tilanus, Remo P.J.; Savolainen, Tuomas; Impellizzeri, C.M. Violette; Alberdi, Antxon; Baczko, Anne-Kathrin; Gómez, José L.; Lu, Ru-Sen; Paraschos, Georgios F.; Traianou, Efthalia; Goddi, Ciriaco; Kim, Daewon; Lisakov, Mikhail; Kovalev, Yuri Y.; Voitsik, Petr A.; Kirill V. Sokolovsky, Kirill V.; Akiyama, Kazunori; Albentosa-Ruíz, Ezequiel; Alef, Walter; Carlos Algaba, Juan; Anantua, Richard; Asada, Keiichi; Azulay, Rebecca; Bach, Uwe; Ball, David; Balokovi´c, Mislav; Bandyopadhyay, Bidisha; Barrett, John; Bauböck, Michi; Benson, Bradford A.; Bintley, Dan; Blundell, Raymond; Bouman, Katherine L.; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broderick, Avery E.; Broguiere, Dominique; Bronzwaer, Thomas; Bustamante, Sandra; Byun, Do-Young; Carlstrom, John E.; Ceccobello, Chiara; Chael, Andrew; Chang, Dominic O.; Chatterjee, Koushik; Chatterjee, Shami; Chen, Ming-Tang; Chen, Yongjun; Cheng, Xiaopeng; Cho, Ilje; Christian, Pierre; Conroy, Nicholas S.; Conway, John E.; Cordes, James M.; Crawford, Thomas M.; Cruz-Osorio, Alejandro; Cui, Yuzhu; Curd, Brandon; Dahale, Rohan; Davelaar, Jordy; De Laurentis, Mariafelicia; Deane, Roger; Dempsey, Jessica; Desvignes, Gregory; Dexter, Jason; Dhruv, Vedant; Dihingia, Indu K.; Dougall, Sean Taylor; Dzib, Sergio A.; Eatough, Ralph P.; Emami, Razieh; Falcke, Heino; Farah, Joseph; Fomalont, Edward; Ford, H. Alyson; Foschi, Marianna; Fraga-Encinas, Raquel; Freeman, William T.; Friberg, Per; Fromm, Christian M.; Fuentes, Antonio; Galison, Peter; Gammie, Charles F.; García, Roberto; Gentaz, Olivier; Georgiev, Boris; Gold, Roman; Gómez-Ruiz, Arturo I.; Gu, Minfeng; Gurwell, Mark; Hada, Kazuhiro; Haggard, Daryl; Haworth, Kari; Hecht, Michael H.; Hesper, Ronald; Heumann, Dirk; Ho, Luis C.; Ho, Paul; Honma, Mareki; Huang, Chih-Wei L.; Huang, Lei; Hughes, David H.; Ikeda, Shiro; Inoue, Makoto; James, David J.; Jannuzi, Buell T.; Jeter, Britton; Jiang, Wu; Jiménez-Rosales, Alejandra; Jorstad, Svetlana; Joshi, Abhishek V.; Jung, Taehyun; Karami, Mansour; Karuppusamy, Ramesh; Kawashima, Tomohisa; Keating, Garrett K.; Kettenis, Mark; Kim, Dong-Jin; Kim, Jae-Young; Kim, Jongsoo; Kim, Junhan; Kino, Motoki; Koay, Jun Yi; Kocherlakota, Prashant; Kofuji, Yutaro; Koyama, Shoko; Kramer, Carsten; Kramer, Joana A.; Kramer, Michael; Kuo, Cheng-Yu; La Bella, Noemi; Lauer, Tod R.; Lee, Daeyoung; Leung, Po Kin; Levis, Aviad; Li, Zhiyuan; Lico, Rocco; Lindahl, Greg; Lindqvist, Michael; Liu, Jun; Liu, Kuo; Liuzzo, Elisabetta; Lo, Wen-Ping; Loinard, Laurent; Lonsdale, Colin J.; Lowitz, Amy E.; MacDonald, Nicholas R.; Mao, Jirong; Marchili, Nicola; Marko, Sera; Marrone, Daniel P.; Marscher, Alan P.; Martí-Vidal, Iván; Matsushita, Satoki; Matthews, Lynn D.; Medeiros, Lia; Menten, Karl M.; Michalik, Daniel; Mizuno, Izumi; Mizuno, Yosuke; Moriyama, Kotaro; Moscibrodzka, Monika; Mulaudzi, Wanga; Müller, Cornelia; Müller, Hendrik; Mus, Alejandro; Musoke, Gibwa; Myserlis, Ioannis; Nadolski, Andrew; Nagai, Hiroshi; Nagar, Neil M.; Nakamura, Masanori; Narayanan, Gopal; Natarajan, Iniyan; Nathanail, Antonios; Fuentes, Santiago Navarro; Neilsen, Joey; Neri, Roberto; Ni, Chunchong; Noutsos, Aristeidis; Nowak, Michael A.; Oh, Junghwan; Okino, Hiroki; Olivares Sánchez, Héctor R.; Ortiz-León, Gisela N.; Oyama, Tomoaki; Özel, Feryal; Palumbo, Daniel C.M.; Park, Jongho; Parsons, Harriet; Patel, Nimesh; Pen, Ue-Li; Pesce, Dominic W.; Piétu, Vincent; Plambeck, Richard; PopStefanija, Aleksandar; Porth, Oliver; Pötzl, Felix M.; Prather, Ben; Preciado-López, Jorge A.; Principe, Giacomo; Psaltis, Dimitrios; Pu, Hung-Yi; Ramakrishnan, Venkatessh; Rao, Ramprasad; Rawlings, Mark G.; Ricarte, Angelo; Ripperda, Bart; Roelofs, Freek; Rogers, Alan; Romero-Cañizales, Cristina; Roshanineshat, Arash; Rottmann, Helge; Roy, Alan L.; Ruiz, Ignacio; Ruszczyk, Chet; Rygl, Kazi L. J.; Sánchez, Salvador; Sánchez-Argüelles, David; Sánchez-Portal, Miguel; Sasada, Mahito; Satapathy, Kaushik; Schloerb, F. Peter; Schonfeld, Jonathan; Schuster, Karl-Friedrich; Shao, Lijing; Shen, Zhiqiang; Small, Des; Sohn, Bong Won; SooHoo, Jason; Sosapanta Salas, León David; Souccar, Kamal; Stanway, Joshua S.; Sun, He; Tazaki, Fumie; Tetarenko, Alexandra J.; Tiede, Paul; Titus, Michael; Torne, Pablo; Toscano, Teresa; Trent, Tyler; Trippe, Sascha; Turk, Matthew; Van Bemmel, Ilse; Van Langevelde, Huib J.; Van Rossum, Daniel R.; Vos, Jesse; Wagner, Jan; Ward-Thompson, Derek; Wardle, John; Washington, Jasmin E.; Weintroub, Jonathan; Wharton, Robert; Wiik, Kaj; Witzel, Gunther; Wondrak, Michael F.; Wong, George N.; Wu, Qingwen; Yadlapalli, Nitika; Yamaguchi, Paul; Yfantis, Aristomenis; Yoon, Doosoo; Young, André; Young, Ken; Younsi, Ziri; Yu, Wei; Yuan, Feng; Yuan, Ye-Fei; Zensus, J. Anton; Zhang, Shuo; Zhao, Guang-Yao; Zhao, Shan-Shan (EDP Sciences, 2025-03)
CONTEXT : The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed, including the main science targets, Sgr A* and M 87, and various calibrators. Sixteen sources were AGN. AIMS : We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-Königl (BK) jet model. In particular, we aimed to study the signatures of jet acceleration and magnetic energy conversion. METHODS : We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components (1749+096, 1055+018, BL Lac, J0132–1654, J0006–0623, CTA 102, and 3C 454.3) and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2–86 GHz range. Combining these data into a multifrequency EHT+ data set, we studied the dependences of the VLBI core component flux density, size, and brightness temperature on the frequency measured in the AGN host frame (and hence on the distance from the central black hole), characterizing them with power law fits. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole. RESULTS : Our observations spanning event horizon to parsec scales indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Only some of the discrepancies may be alleviated by tweaking the model parameters or the jet collimation profile. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations. For our sample, we estimate a general radial dependence of the Doppler factor δ ∝ r≤0.5. This interpretation is consistent with a magnetically accelerated sub-parsec jet. We also estimate a steep decrease of the magnetic field strength with radius B ∝ r−3, hinting at jet acceleration or efficient magnetic energy dissipation.
Investigation of the structural stability, electronic properties, and thermoelectric performance of graphene enhanced (BA)₂SnI₄ two-dimensional halide perovskite for advanced thermoelectric applications
Elegbeleye, Ife; Fwalo, Chewe; Mapasha, Edwin; Maluta, Eric; Maphanga, Regina (Springer, 2026-04-28)
The toxicity of lead and instability remain primary obstacles limiting the widespread application of perovskite materials. Two-dimensional (2D) perovskites have demonstrated significantly improved stability compared to their three-dimensional (3D) counterparts due to enhanced hydrophobicity and resistance to degradation. However, studies investigating the thermoelectric potential of 2D perovskites remain limited, underscoring the need for a deeper understanding of their behavior and scalability for electronic and thermoelectric applications. In this study, density functional theory (DFT) is employed to investigate the structural stability, electronic properties, and thermoelectric performance of graphene-enhanced 2D (BA)₂SnI₄ perovskites. Graphene is of particular interest due to its large surface area, flexibility, transparency, and high charge-carrier mobility. Our results indicate that pristine (BA)₂SnI₄ exhibit semiconducting characteristics with well defined band gap, making it suitable as a light-absorbing layer in optoelectronic devices. It also exhibits excellent thermoelectric performance, with a high Seebeck coefficient, peak power factor of 1.6×10⁻² W·m⁻¹·K⁻², and maximum figure of merit (ZT) of 3.5 at 100 K, making it ideal for low-temperature thermoelectric applications. Moreover, incorporating graphene improves electrical conductivity and stabilizes the power factor at 200–800 K, increases thermal conductivity while lowering the Seebeck coefficient and ZT to <0.3. These results reveal an offset between stability and thermoelectric efficiency, pristine (BA)₂SnI₄ is optimal for low-temperature thermoelectrics, whereas graphene-modified systems, despite having lower ZT, are promising for moderate-to-high temperature applications wherein enhanced conductivity and thermal stability are crucial.
Characterization of 3D/2D Sn-based perovskite heterostructure thin films prepared by sequential physical vapor deposition
Sembito, Alex; Mwabora, Julius M.; Nyongesa, Francis W.; Diale, M. (Mmantsae Moche) (Elsevier, 2026-04-01)
Please read abstract in the article. HIGHLIGHTS • A thick two-dimensional layer lowers the quality of the films. • Crystallinity and film morphology improves with annealing time. • Two-dimensional layer slows down the nucleation rate of the three-dimensional-perovskite. • Annealing suppresses the defect density and improves electron mobility of the films.
Structural evolution of polycrystalline SiC and migration behavior of silver (Ag) following sequential implantation of silver and helium and subsequent annealing at 1200 °C and 1300 °C
Mtsi, Sive Zizo; Abdalla, Zaki Adam Yousif; Abdelbagi, Hesham Abdelbagi Ali; Mlambo, Mbuso; Sohatsky, A.; Skuratov, Vladimir Alexeevich; Nguyen, T.; Njoroge, Eric Gitau; Hlatshwayo, Thulani Thokozani (Elsevier, 2026-04)
This study reports on the effects of sequential silver (Ag) and helium (He) ion implantation, followed by heat treatment, on the structural evolution of silicon carbide (SiC) and the migration behavior of Ag. Polycrystalline SiC samples were implanted with 360 keV Ag ions at 350 °C to a fluence of 2 × 10 ¹ ⁶ cm⁻². A subset of these Ag-implanted samples was subsequently implanted with He ions at the same temperature to a fluence of 1 × 10 ¹ ⁷ cm⁻². Both Ag-only and Ag+He sequentially implanted samples underwent isochronal annealing at 1200 °C and 1300 °C for 5 h. Ag implantation introduced and retained structural defects in SiC. In contrast, sequential He implantation resulted in the formation of helium bubbles in the implanted region, along with surface blistering and the development of holes. These surface features acted as diffusion pathways for Ag during He implantation, leading to approximately 8% Ag migration in the sequentially implanted samples. Graphite crystals were detected in sequentially implanted samples both before and after annealing; at high temperatures, these structures inhibited recrystallization, while Ag-only samples exhibited greater recovery. Limited recrystallization at high temperatures was also associated with the growth of He-induced cavities, which promoted the formation of larger Ag precipitates. At 1300 °C, enhanced atomic mobility, helium release, and cavity shrinkage produced a denser population of smaller and more uniform cavities that act as effective Ag trapping sites. This behavior is linked to the high stress fields present in the sequentially implanted samples following annealing. At 1300 °C, Ag in both sample types shifted further toward the SiC bulk, again due to elevated stress levels. While no Ag loss was observed in Ag-only samples, sequentially implanted samples exhibited significant Ag loss, reaching ∼13% at 1200 °C and ∼23% at 1300 °C. These findings highlight the critical influence of helium on defect evolution, cavity morphology, Ag redistribution, and the thermal stability of SiC under extreme high-temperature conditions, with direct relevance to fission-product retention and TRISO fuel integrity.
The impact of project-based learning in the physics first-year module
Thabethe, Thabsile Theodora; Mwambakana, Jeanine (Common Ground Research Networks, 2025-03-25)
This study investigated the impact of project-based learning (PBL) on academics and personal development in a first-year physics module within an extended curriculum program. The primary objectives included assessing how PBL enhanced students’ conceptual understanding of physics, fostering the acquisition of transferable skills and promoting self-discovery. A mixed-methods approach was employed, analyzing survey responses from 338 participants across 2021 and 2022 cohorts, using qualitative and quantitative tools to evaluate their experiences. Students collaborated in groups to design and construct physics-based models utilizing everyday materials, with an emphasis on practical applications of theoretical knowledge. The findings reveal that 94% of students reported an enhanced understanding of physics concepts post project. Notable skill gains included communication, collaboration, leadership, and time management. While many students appreciated the collaborative environment, challenges such as unequal contributions and communication issues were highlighted, particularly in randomly assigned groups. Beyond academics, the project facilitated personal growth, fostering patience, adaptability, and self-reflection, while emphasizing the relevance of physics in daily life. However, constraints related to resources and group dynamics necessitate institutional support and diversified pedagogical approaches. The results show PBL’s transformative potential, positioning it as an effective strategy for bridging theoretical knowledge with practical skill development.
Enhanced titanium carbide MXene structure with CuO quantum dots as an electrode for advanced supercapacitor applications
Rantsotlhe, Mpho; Otun, Kabir Opeyemi; Adam, Rashed Ali Mohamed; Rutavi, Gift; Chigome, Samuel; Manyala, Ncholu I. (Royal Society of Chemistry, 2026-05-12)
Please read abstract in the article.
Discovery of a nearby radio relic in the low-mass, merging cluster Abell 4067
Magolego, Isaac S.; Deane, Roger; Thorat, Kshitij; Heywood, Ian; Spilker, Justin; Somboonpanyakul, Taweewat; Zhou, Dazhi; Aravena, Manuel; Vieira, Joaquin D.; Phadke, Kedar A.; Bleem, Lindsey E.; Chapman, Scott C. (Oxford University Press, 2026-05)
Please read abstract in the article.

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