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1,307 results on '"Meintjes, P."'

1. GRB 240529A: A Tale of Two Shocks

Author

Sun, Tian-Rui, Geng, Jin-Jun, Yan, Jing-Zhi, Hu, You-Dong, Wu, Xue-Feng, Castro-Tirado, Alberto J., Yang, Chao, Ping, Yi-Ding, Hu, Chen-Ran, Xu, Fan, Gao, Hao-Xuan, Jiang, Ji-An, Zhu, Yan-Tian, Xue, Yongquan, Pérez-García, Ignacio, Wu, Si-Yu, Fernández-García, Emilio, Caballero-García, María D., Sánchez-Ramírez, Rubén, Guziy, Sergiy, Olivares, Ignacio, del Pulgar, Carlos Jesus Pérez, Castellón, A., Castillo, Sebastián, Xiong, Ding-Rong, Pandey, Shashi B., Hiriart, David, García-Segura, Guillermo, Lee, William H., Carrasco-García, I. M., Park, Il H., Meintjes, Petrus J., van Heerden, Hendrik J., Martín-Carrillo, Antonio, Hanlon, Lorraine, Zhang, Bin-Bin, Maury, Alain, Hernández-García, L., Gritsevich, Maria, Rossi, Andrea, Maiorano, Elisabetta, Cusano, Felice, D'Avanzo, Paolo, Ferro, Matteo, Melandri, Andrea, De Pasquale, Massimiliano, Brivio, Riccardo, Fang, Min, Fan, Lu-Lu, Hu, Wei-Da, Wan, Zhen, Hu, Lei, Zuo, Ying-Xi, Tang, Jin-Long, Zhang, Xiao-Ling, Zheng, Xian-Zhong, Li, Bin, Luo, Wen-Tao, Liu, Wei, Wang, Jian, Zhang, Hong-Fei, Liu, Hao, Gao, Jie, Liang, Ming, Wang, Hai-Ren, Yao, Da-Zhi, Cheng, Jing-Quan, Zhao, Wen, and Dai, Zi-Gao

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Thanks to the rapidly increasing time-domain facilities, we are entering a golden era of research on gamma-ray bursts (GRBs). In this Letter, we report our observations of GRB 240529A with the Burst Optical Observer and Transient Exploring System, the 1.5-meter telescope at Observatorio Sierra Nevada, the 2.5-meter Wide Field Survey Telescope of China, the Large Binocular Telescope, and the Telescopio Nazionale Galileo. The prompt emission of GRB 240529A shows two comparable energetic episodes separated by a quiescence time of roughly 400 s. Combining all available data on the GRB Coordinates Network, we reveal the simultaneous apparent X-ray plateau and optical re-brightening around $10^3-10^4$ s after the burst. Rather than the energy injection from the magnetar as widely invoked for similar GRBs, the multi-wavelength emissions could be better explained as two shocks launched from the central engine separately. The optical peak time and our numerical modeling suggest that the initial bulk Lorentz factor of the later shock is roughly 50, which indicates that the later jet should be accretion-driven and have a higher mass loading than a typical one. The quiescence time between the two prompt emission episodes may be caused by the transition between different accretion states of a central magnetar or black hole, or the fall-back accretion process. A sample of similar bursts with multiple emission episodes in the prompt phase and sufficient follow-up could help to probe the underlying physics of GRB central engines., Comment: Resubmitted to ApJL after addressing the referee's comments; comments are welcome

Published
2024

2. Millinovae: a new class of transient supersoft X-ray sources

Author

Mróz, Przemek, Król, Krzysztof, Szegedi, Hélène, Charles, Philip, Page, Kim L., Udalski, Andrzej, Buckley, David A. H., Dewangan, Gulab, Meintjes, Pieter, Szymański, Michał K., Soszyński, Igor, Pietrukowicz, Paweł, Kozłowski, Szymon, Poleski, Radosław, Skowron, Jan, Ulaczyk, Krzysztof, Gromadzki, Mariusz, Rybicki, Krzysztof, Iwanek, Patryk, Wrona, Marcin, and Mróz, Mateusz J.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Some accreting binary systems containing a white dwarf (such as classical novae or persistent supersoft sources) are seen to emit low energy X-rays with temperatures of ~10^6 K and luminosities exceeding 10^35 erg/s. These X-rays are thought to originate from nuclear burning on the white dwarf surface, either caused by a thermonuclear runaway (classical novae) or a high mass accretion rate that sustains steady nuclear burning (persistent sources). The discovery of transient supersoft X-rays from ASASSN-16oh challenged these ideas, as no signatures of nuclear fusion were detected, and the origin of these X-rays remains controversial. It was unclear whether this star was one of a kind or representative of a larger, as yet undiscovered, group. Here we present the discovery of 29 stars located in the direction of the Magellanic Clouds exhibiting long-duration, symmetrical optical outbursts similar to that seen in ASASSN-16oh. We observed one of these objects during an optical outburst and found it to be emitting transient supersoft X-rays, while no signatures of mass ejection (indicative of a classical nova eruption) were detected. We therefore propose that these objects form a homogeneous group of transient supersoft X-ray sources, which we dub `millinovae' because their optical luminosities are approximately a thousand times fainter than those of ordinary classical novae., Comment: submitted to AAS Journals

Published
2024

3. H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883

Author

Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Borowska, J., Bouyahiaoui, M., Brose, R., Brown, A., Brun, F., Bruno, B., Bulik, T., Burger-Scheidlin, C., Caroff, S., Casanova, S., Celic, J., Cerruti, M., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djuvsland, J., Dmytriiev, A., Egberts, K., Einecke, S., Ernenwein, J. -P., Fontaine, G., Funk, S., Gabici, S., Gallant, Y. A., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Haerer, L., Heß, B., Hofmann, W., Holch, T. L., Holler, M., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khangulyan, D., Khatoon, R., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kundu, A., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Mackey, J., Malyshev, D., Martí-Devesa, G., Marx, R., Mehta, A., Meintjes, P. J., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Murach, T., de Naurois, M., Niemiec, J., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Pensec, U., Peron, G., Prokhorov, D. A., Pühlhofer, G., Punch, M., Quirrenbach, A., Regeard, M., Reimer, A., Reimer, O., Reis, I., Ren, H., Rieger, F., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Shapopi, J. N. S., Spencer, S., Stawarz, Ł., Steenkamp, R., Steinmassl, S., Steppa, C., Streil, K., Sushch, I., Takahashi, T., Tanaka, T., Taylor, A. M., Terrier, R., Thorpe-Morgan, C., Tluczykont, M., Unbehaun, T., van Eldik, C., van Soelen, B., Vecchi, M., Venter, C., Vink, J., Wach, T., Wagner, S. J., Werner, F., Wierzcholska, A., Zacharias, M., Zdziarski, A. A., Zech, A., and Żywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

PSR B1259-63 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 year period, around an O9.5Ve star. At orbital phases close to periastron passages, the system radiates bright and variable non-thermal emission. We report on an extensive VHE observation campaign conducted with the High Energy Stereoscopic System, comprised of ~100 hours of data taken from $t_p-24$ days to $t_p+127$ days around the system's 2021 periastron passage. We also present the timing and spectral analyses of the source. The VHE light curve in 2021 is consistent with the stacked light curve of all previous observations. Within the light curve, we report a VHE maximum at times coincident with the third X-ray peak first detected in the 2021 X-ray light curve. In the light curve -- although sparsely sampled in this time period -- we see no VHE enhancement during the second disc crossing. In addition, we see no correspondence to the 2021 GeV flare in the VHE light curve. The VHE spectrum obtained from the analysis of the 2021 dataset is best described by a power law of spectral index $\Gamma = 2.65 \pm 0.04_{\text{stat}}$ $\pm 0.04_{\text{sys}}$, a value consistent with the previous H.E.S.S. observations of the source. We report spectral variability with a difference of $\Delta \Gamma = 0.56 ~\pm~ 0.18_{\text{stat}}$ $~\pm~0.10_{\text{sys}}$ at 95% c.l., between sub-periods of the 2021 dataset. We also find a linear correlation between contemporaneous flux values of X-ray and TeV datasets, detected mainly after $t_p+25$ days, suggesting a change in the available energy for non-thermal radiation processes. We detect no significant correlation between GeV and TeV flux points, within the uncertainties of the measurements, from $\sim t_p-23$ days to $\sim t_p+126$ days. This suggests that the GeV and TeV emission originate from different electron populations., Comment: accepted to A&A

Published
2024

4. Fires in the deep: The luminosity distribution of early-time gamma-ray-burst afterglows in light of the Gamow Explorer sensitivity requirements

Author

Kann, D. A., White, N. E., Ghirlanda, G., Oates, S. R., Melandri, A., Jelinek, M., Postigo, A. de Ugarte, Levan, A. J., Martin-Carrillo, A., Paek, G. S. -H., Izzo, L., Blazek, M., Thone, C., Fernandez, J. F. Agui, Salvaterra, R., Tanvir, N. R., Chang, T. -C., O'Brien, P., Rossi, A., Perley, D. A., Im, M., Malesani, D. B., Antonelli, A., Covino, S., Choi, C., D'Avanzo, P., D'Elia, V., Dichiara, S., Fausey, H. M., Fugazza, D., Gomboc, A., Gorski, K. M., Granot, J., Guidorzi, C., Hanlon, L., Hartmann, D. H., Hudec, R., Jun, H. D., Kim, J., Kim, Y., Klose, S., Kluzniak, W., Kobayashi, S., Kouveliotou, C., Lidz, A., Marongiu, M., Martone, R., Meintjes, P., Mundell, C. G., Murphy, D., Nalewajko, K., Park, W. -K., Sz'ecsi, D., Smith, R. J., Stecklum, B., Steele, I. A., Strobl, J., Sung, H. -I, Updike, A., Urata, Y., and van der Horst, A. J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (z > 5), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights that can be used to spectrally fingerprint the intergalactic medium and host galaxy during the period of reionization. Future missions such as Gamow Explorer are being proposed to unlock this potential by increasing the rate of identification of high-z GRBs to rapidly trigger observations from 6-10 m ground telescopes, JWST, and the Extremely Large Telescopes. Gamow was proposed to the NASA 2021 Medium-Class Explorer (MIDEX) program as a fast-slewing satellite featuring a wide-field lobster-eye X-ray telescope (LEXT) to detect and localize GRBs, and a 30 cm narrow-field multi-channel photo-z infrared telescope (PIRT) to measure their photometric redshifts using the Lyman-alpha dropout technique. To derive the PIRT sensitivity requirement we compiled a complete sample of GRB optical-near-infrared afterglows from 2008 to 2021, adding a total of 66 new afterglows to our earlier sample, including all known high-z GRB afterglows. We performed full light-curve and spectral-energy-distribution analyses of these afterglows to derive their true luminosity at very early times. For all the light curves, where possible, we determined the brightness at the time of the initial finding chart of Gamow, at different high redshifts and in different NIR bands. We then followed the evolution of the luminosity to predict requirements for ground and space-based follow-up. We find that a PIRT sensitivity of 15 micro-Jy (21 mag AB) in a 500 s exposure simultaneously in five NIR bands within 1000s of the GRB trigger will meet the Gamow mission requirement to recover > 80% of all redshifts at z > 5., Comment: 44 pages, 10 figures, 1 table. Accepted for publication in Astronomy and Astrophysics 15 Feb 2024. Abstract abridged for arXiv

Published
2024
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6. Testing novel strategies for patients hospitalised with HIV-associated disseminated tuberculosis (NewStrat-TB): protocol for a randomised controlled trial

Author

Namale, Phiona E., Boloko, Linda, Vermeulen, Marcia, Haigh, Kate A., Bagula, Fortuna, Maseko, Alexis, Sossen, Bianca, Lee-Jones, Scott, Msomi, Yoliswa, McIlleron, Helen, Mnguni, Ayanda Trevor, Crede, Thomas, Szymanski, Patryk, Naude, Jonathan, Ebrahim, Sakeena, Vallie, Yakoob, Moosa, Muhammed Shiraz, Bandeker, Ismail, Hoosain, Shakeel, Nicol, Mark P., Samodien, Nazlee, Centner, Chad, Dowling, Wentzel, Denti, Paolo, Gumedze, Freedom, Little, Francesca, Parker, Arifa, Price, Brendon, Schietekat, Denzil, Simmons, Bryony, Hill, Andrew, Wilkinson, Robert J., Oliphant, Ida, Hlungulu, Siphokazi, Apolisi, Ivy, Toleni, Monica, Asare, Zimkhitha, Mpalali, Mkanyiseli Kenneth, Boshoff, Erica, Prinsloo, Denise, Lakay, Francisco, Bekiswa, Abulele, Jackson, Amanda, Barnes, Ashleigh, Johnson, Ryan, Wasserman, Sean, Maartens, Gary, Barr, David, Schutz, Charlotte, and Meintjes, Graeme

Published
2024
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9. Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S

Author

Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Aschersleben, J., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., Borowska, J., Bouyahiaoui, M., Bradascio, F., Brose, R., Brun, F., Bruno, B., Bulik, T., Scheidlin, C. Burger, Cangemi, F., Caroff, S., Casanova, S., Celic, J., Cerruti, M., Chambery, P., Chand, T., Chandra, S., Chen, A., Chibueze, J., Chibueze, O., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Ataï, A., Dmytriiev, A., Egberts, K., Einecke, S., Ernenwein, J. P., Feijen, K., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Füssling, M., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Goswami, P., Grolleron, G., Grondin, M. -H., Haerer, L., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Khélifi, B., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lang, R. G., Stum, S. Le, Leitl, F., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marinos, P., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Prokhorov, D. A., Pühlhofer, G., Quirrenbach, A., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Salzmann, H., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Sinha, A., Sol, H., Specovius, A., Spencer, S., Stawarz, Ł., Steinmassl, S., Sushch, I., Suzuki, H., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Vecchi, M., Venter, C., Vink, J., Wagner, S. J., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zouari, S., and Żywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of gamma-ray emission on angular scales > 2 deg poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended gamma-ray emission around the Geminga pulsar with a radius of at least 3 deg in the energy range 0.5-40 TeV. We find no indications for statistically significant asymmetries or energy-dependent morphology. A flux normalisation of $(2.8\pm0.7)\times10^{-12}$ cm$^{-2}$s$^{-1}$TeV$^{-1}$ at 1 TeV is obtained within a 1 deg radius region around the pulsar. To investigate the particle transport within the halo of energetic leptons around the pulsar, we fitted an electron diffusion model to the data. The normalisation of the diffusion coefficient obtained of $D_0 = 7.6^{+1.5}_{-1.2} \times 10^{27}$ cm$^2$s$^{-1}$, at an electron energy of 100 TeV, is compatible with values previously reported for the pulsar halo around Geminga, which is considerably below the Galactic average., Comment: 16 pages, 15 figures, 7 tables. Accepted for publication in Astronomy & Astrophysics

Published
2023
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10. Testing novel strategies for patients hospitalised with HIV-associated disseminated tuberculosis (NewStrat-TB): protocol for a randomised controlled trial

Author

Phiona E. Namale, Linda Boloko, Marcia Vermeulen, Kate A. Haigh, Fortuna Bagula, Alexis Maseko, Bianca Sossen, Scott Lee-Jones, Yoliswa Msomi, Helen McIlleron, Ayanda Trevor Mnguni, Thomas Crede, Patryk Szymanski, Jonathan Naude, Sakeena Ebrahim, Yakoob Vallie, Muhammed Shiraz Moosa, Ismail Bandeker, Shakeel Hoosain, Mark P. Nicol, Nazlee Samodien, Chad Centner, Wentzel Dowling, Paolo Denti, Freedom Gumedze, Francesca Little, Arifa Parker, Brendon Price, Denzil Schietekat, Bryony Simmons, Andrew Hill, Robert J. Wilkinson, Ida Oliphant, Siphokazi Hlungulu, Ivy Apolisi, Monica Toleni, Zimkhitha Asare, Mkanyiseli Kenneth Mpalali, Erica Boshoff, Denise Prinsloo, Francisco Lakay, Abulele Bekiswa, Amanda Jackson, Ashleigh Barnes, Ryan Johnson, Sean Wasserman, Gary Maartens, David Barr, Charlotte Schutz, and Graeme Meintjes

Subjects
HIV, Disseminated tuberculosis, High dose rifampicin, Levofloxacin, Prednisone, Randomised controlled trial, Medicine (General), R5-920
Abstract

Abstract Background HIV-associated tuberculosis (TB) contributes disproportionately to global tuberculosis mortality. Patients hospitalised at the time of the diagnosis of HIV-associated disseminated TB are typically severely ill and have a high mortality risk despite initiation of tuberculosis treatment. The objective of the study is to assess the safety and efficacy of both intensified TB treatment (high dose rifampicin plus levofloxacin) and immunomodulation with corticosteroids as interventions to reduce early mortality in hospitalised patients with HIV-associated disseminated TB. Methods This is a phase III randomised controlled superiority trial, evaluating two interventions in a 2 × 2 factorial design: (1) high dose rifampicin (35 mg/kg/day) plus levofloxacin added to standard TB treatment for the first 14 days versus standard tuberculosis treatment and (2) adjunctive corticosteroids (prednisone 1.5 mg/kg/day) versus identical placebo for the first 14 days of TB treatment. The study population is HIV-positive patients diagnosed with disseminated TB (defined as being positive by at least one of the following assays: urine Alere LAM, urine Xpert MTB/RIF Ultra or blood Xpert MTB/RIF Ultra) during a hospital admission. The primary endpoint is all-cause mortality at 12 weeks comparing, first, patients receiving intensified TB treatment to standard of care and, second, patients receiving corticosteroids to those receiving placebo. Analysis of the primary endpoint will be by intention to treat. Secondary endpoints include all-cause mortality at 2 and 24 weeks. Safety and tolerability endpoints include hepatoxicity evaluations and corticosteroid-related adverse events. Discussion Disseminated TB is characterised by a high mycobacterial load and patients are often critically ill at presentation, with features of sepsis, which carries a high mortality risk. Interventions that reduce this high mycobacterial load or modulate associated immune activation could potentially reduce mortality. If found to be safe and effective, the interventions being evaluated in this trial could be easily implemented in clinical practice. Trial registration ClinicalTrials.gov NCT04951986. Registered on 7 July 2021 https://clinicaltrials.gov/study/NCT04951986

Published
2024
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11. Phase 2 Safety and Antiviral Activity of SAB-185, a Novel Polyclonal Antibody Therapy for Nonhospitalized Adults With COVID-19

Author

Taiwo, Babafemi O, Chew, Kara W, Moser, Carlee, Wohl, David Alain, Daar, Eric S, Li, Jonathan Z, Greninger, Alexander L, Bausch, Christoph, Luke, Thomas, Hoover, Keila, Neytman, Gene, Giganti, Mark J, Olefsky, Maxine, Javan, Arzhang Cyrus, Fletcher, Courtney V, Eron, Joseph J, Currier, Judith S, Hughes, Michael D, Smith, Davey M, Hosey, Lara, Roa, Jhoanna, Patel, Nilam, Coombs, Robert, Degli-Angeli, Emily, Goecker, Erin, Daza, Glenda, Harb, Socorro, Dragavon, Joan, Aldrovandi, Grace, Murtaugh, William, Cooper, Marlene, Gutzman, Howard, Knowles, Kevin, Erhardt, Bill, Waring, Lorraine, Hessinger, Diane, Meintjes, Graeme A, Murray, Barbara E, Ray, Stuart Campbell, Rolla, Valeria Cavalcanti, Saloojee, Haroon, Tsiatis, Anastasios A, Volberding, Paul A, Kimmelman, Jonathan, Glidden, David, and Hunsberger, Sally

Subjects
Biomedical and Clinical Sciences, Clinical Sciences, Coronaviruses, Clinical Research, Infectious Diseases, Emerging Infectious Diseases, Clinical Trials and Supportive Activities, 6.1 Pharmaceuticals, Evaluation of treatments and therapeutic interventions, Good Health and Well Being, Adult, Humans, COVID-19, SARS-CoV-2, Antiviral Agents, RNA, Viral, Immunoglobulin G, Double-Blind Method, SAB-185, antibody, polyclonal, transchromosomic, treatment, ACTIV-2/A5401 Study Team, Biological Sciences, Medical and Health Sciences, Microbiology, Biological sciences, Biomedical and clinical sciences, Health sciences
Abstract

BackgroundSAB-185, a novel fully human IgG polyclonal immunoglobulin product, underwent phase 2 evaluation for nonhospitalized adults with mild-moderate coronavirus disease 2019 (COVID-19).MethodsParticipants received intravenous SAB-185 3840 units/kg (low-dose) or placebo, or 10 240 units/kg (high-dose) or placebo. Primary outcome measures were nasopharyngeal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA < lower limit of quantification (LLOQ) at study days 3, 7, and 14, time to symptomatic improvement, and safety through day 28.ResultsTwo-hundred thirteen participants received low-dose SAB-185/placebo (n = 107/106) and 215 high-dose SAB-185/placebo (n = 110/105). The proportions with SARS-CoV-2 RNA < LLOQ were higher for SAB-185 versus placebo at days 3 and 7 and similar at day 14, and significantly higher at day 7 for high-dose SAB-185 versus placebo only, relative risk 1.23 (95% confidence interval, 1.01-1.49). At day 3, SARS-CoV-2 RNA levels were lower with low-dose and high-dose SAB-185 versus placebo: differences in medians of -0.78 log10 copies/mL (P = .08) and -0.71 log10 copies/mL (P = .10), respectively. No difference was observed in time to symptom improvement: median 11/10 days (P = .24) for low-dose SAB-185/placebo and 8/10 days (P = .50) for high-dose SAB-185/placebo. Grade ≥3 adverse events occurred in 5%/13% of low-dose SAB-185/placebo and 9%/12% of high-dose SAB-185/placebo.ConclusionsSAB-185 was safe and generally well tolerated and demonstrated modest antiviral activity in predominantly low-risk nonhospitalized adults with COVID-19. Clinical Trials Registration. NCT04518410.

Published
2023

12. Clinical utility of WHO-recommended screening tools and development and validation of novel clinical prediction models for pulmonary tuberculosis screening among outpatients living with HIV: an individual participant data meta-analysis

Author

Dhana, Ashar, Gupta, Rishi K, Hamada, Yohhei, Kengne, Andre P, Kerkhoff, Andrew D, Yoon, Christina, Cattamanchi, Adithya, Reeve, Byron WP, Theron, Grant, Ndlangalavu, Gcobisa, Wood, Robin, Drain, Paul K, Calderwood, Claire J, Noursadeghi, Mahdad, Boyles, Tom, Meintjes, Graeme, Maartens, Gary, and Barr, David A

Subjects
Tuberculosis, HIV/AIDS, Clinical Research, Rare Diseases, Infectious Diseases, Infection, Good Health and Well Being, Adult, Humans, Outpatients, Models, Statistical, Sensitivity and Specificity, HIV Infections, Prognosis, Tuberculosis, Pulmonary, C-Reactive Protein, Medical Physiology, Respiratory System
Abstract

BackgroundThe World Health Organization (WHO) recommends that outpatient people living with HIV (PLHIV) undergo tuberculosis screening with the WHO four-symptom screen (W4SS) or C-reactive protein (CRP) (5 mg·L-1 cut-off) followed by confirmatory testing if screen positive. We conducted an individual participant data meta-analysis to determine the performance of WHO-recommended screening tools and two newly developed clinical prediction models (CPMs).MethodsFollowing a systematic review, we identified studies that recruited adult outpatient PLHIV irrespective of tuberculosis signs and symptoms or with a positive W4SS, evaluated CRP and collected sputum for culture. We used logistic regression to develop an extended CPM (which included CRP and other predictors) and a CRP-only CPM. We used internal-external cross-validation to evaluate performance.ResultsWe pooled data from eight cohorts (n=4315 participants). The extended CPM had excellent discrimination (C-statistic 0.81); the CRP-only CPM had similar discrimination. The C-statistics for WHO-recommended tools were lower. Both CPMs had equivalent or higher net benefit compared with the WHO-recommended tools. Compared with both CPMs, CRP (5 mg·L-1 cut-off) had equivalent net benefit across a clinically useful range of threshold probabilities, while the W4SS had a lower net benefit. The W4SS would capture 91% of tuberculosis cases and require confirmatory testing for 78% of participants. CRP (5 mg·L-1 cut-off), the extended CPM (4.2% threshold) and the CRP-only CPM (3.6% threshold) would capture similar percentages of cases but reduce confirmatory tests required by 24, 27 and 36%, respectively.ConclusionsCRP sets the standard for tuberculosis screening among outpatient PLHIV. The choice between using CRP at 5 mg·L-1 cut-off or in a CPM depends on available resources.

Published
2023

13. Scramble number and tree-cut decompositions

Author

Cenek, Lisa, Ferguson, Lizzie, Gebre, Eyobel, Marcussen, Cassandra, Meintjes, Jason, Morrison, Ralph, Ostermeyer, Liz, Ramakrishna, Shefali, and Weber, Ben

Subjects
Mathematics - Combinatorics, Mathematics - Algebraic Geometry, 05C57, 14T05
Abstract

The scramble number of a graph is an invariant recently developed to study chip-firing games and divisorial gonality. In this paper we introduce the screewidth of a graph, based on a variation of the existing literature on tree-cut decompositions. We prove that this invariant serves as an upper bound on scramble number, though they are not always equal. We study properties of screewidth, and present results and conjectures on its connection to divisorial gonality., Comment: 22 pages, 24 figures

Published
2022

14. Distinct alterations in white matter properties and organization related to maternal treatment initiation in neonates exposed to HIV but uninfected

Author

Ndivhuwo Magondo, Ernesta M. Meintjes, Fleur L. Warton, Francesca Little, Andre J. W. van der Kouwe, Barbara Laughton, Marcin Jankiewicz, and Martha J. Holmes

Subjects
Medicine, Science
Abstract

Abstract HIV exposed-uninfected (HEU) infants and children are at risk of developmental delays as compared to HIV uninfected unexposed (HUU) populations. The effects of exposure to in utero HIV and ART regimens on the HEU the developing brain are not well understood. In a cohort of 2-week-old newborns, we used diffusion tensor imaging (DTI) tractography and graph theory to examine the influence of HIV and ART exposure in utero on neonate white matter integrity and organisation. The cohort included HEU infants born to mothers who started ART before conception (HEUpre) and after conception (HEUpost), as well as HUU infants from the same community. We investigated HIV exposure and ART duration group differences in DTI metrics (fractional anisotropy (FA) and mean diffusivity (MD)) and graph measures across white matter. We found increased MD in white matter connections involving the thalamus and limbic system in the HEUpre group compared to HUU. We further identified reduced nodal efficiency in the basal ganglia. Within the HEUpost group, we observed reduced FA in cortical-subcortical and cerebellar connections as well as decreased transitivity in the hindbrain area compared to HUU. Overall, our analysis demonstrated distinct alterations in white matter integrity related to the timing of maternal ART initiation that influence regional brain network properties.

Published
2024
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15. Prenatal alcohol exposure is associated with changes in placental gene co-expression networks

Author

Maya A. Deyssenroth, Randy P. Williams, Corina Lesseur, Sandra W. Jacobson, Joseph L. Jacobson, Haoxiang Cheng, Promita Bose, Qian Li, Helen Wainwright, Ernesta M. Meintjes, Ke Hao, Jia Chen, and R. Colin Carter

Subjects
Medicine, Science
Abstract

Abstract Alcohol consumption during pregnancy can result in a range of adverse postnatal outcomes among exposed children. However, identifying at-risk children is challenging given the difficulty to confirm prenatal alcohol exposure and the lack of early diagnostic tools. Placental surveys present an important opportunity to uncover early biomarkers to identify those at risk. Here, we report the first transcriptome-wide evaluation to comprehensively evaluate human placental pathways altered by fetal alcohol exposure. In a prospective longitudinal birth cohort in Cape Town, South Africa, we performed bulk tissue RNAseq in placenta samples from 32 women reporting heavy drinking during pregnancy and 30 abstainers/light drinkers. Weighted gene co-expression network analysis (WGCNA) and differential gene expression analysis were performed to assess associations between fetal alcohol exposure and placental gene expression patterns at a network-wide and single gene level, respectively. The results revealed altered expression in genes related to erythropoiesis and angiogenesis, which are implicated in established postnatal phenotypes related to alcohol exposure, including disruptions in iron homeostasis, growth, and neurodevelopment. The reported findings provide insights into the molecular pathways affected by prenatal alcohol exposure and highlight the potential of placental biomarkers for detecting and understanding the effects of alcohol on fetal development.

Published
2024
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16. Bounds on higher graph gonality

Author

Cenek, Lisa, Ferguson, Lizzie, Gebre, Eyobel, Marcussen, Cassandra, Meintjes, Jason, Morrison, Ralph, Ostermeyer, Liz, and Ramakrishna, Shefali

Subjects
Mathematics - Combinatorics, Mathematics - Algebraic Geometry, 05C57, 14T99
Abstract

We prove new lower and upper bounds on the higher gonalities of finite graphs. These bounds are generalizations of known upper and lower bounds for first gonality to higher gonalities, including upper bounds on gonality involving independence number, and lower bounds on gonality by scramble number. We apply our bounds to study the computational complexity of computing higher gonalities, proving that it is NP-hard to compute the second gonality of a graph when restricting to multiplicity-free divisors., Comment: 14 pages, 5 figures

Published
2022

17. Transient behavior of three SU UMa-type dwarf novae; AR Pic, QW Ser and V521 Peg

Author

Szegedi, Hélène, Charles, Philip A., Meintjes, Pieter J., and Odendaal, Alida

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

Changes in the supercycle lengths of some SU UMa-type dwarf novae have been detected by other studies, and indicate that the mass transfer rates noticeably decrease over time. We investigated the supercycle lengths of three SU UMa-type dwarf novae: AR Pic, QW Ser and V521 Peg, to determine if they have detectable changes in their supercycles. We present the results of optical spectroscopic and photometric observations of these sources. Our observations were conducted in 2016 and 2017 at the Boyden Observatory and the Sutherland station of the South African Astronomical Observatory. The quiescent results indicated that all three sources are typical SU UMa-type dwarf novae. We also present results of AR Pic and QW Ser in outburst and of V521 Peg during a precursor outburst and superoutburst. Light curves were supplemented by the Catalina Real-Time Transient Survey, the ASAS-3 and ASAS-SN archives, and the AAVSO International database in order to investigate the long-term behavior of these sources. Our results combined with catalogued properties for all short-period dwarf novae, shows a possible relationship between the supercycle time in SU UMa systems and their orbital periods, which is interpreted as the decline in the mass transfer rate as systems evolve toward and away from the 'period minimum'. At the shortest orbital periods, SU UMa systems are almost indistinguishable from WZ Sge systems. However, we propose that the scaleheight between the secondary's photosphere and L1 may be a factor that distinguish the SU UMa subclasses., Comment: 14 pages, 19 figures, accepted for publication in MNRAS

Published
2022
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18. Evidence for gamma-ray emission from the remnant of Kepler's supernova based on deep H.E.S.S. observations

Author

Collaboration, H. E. S. S., Aharonian, F., Benkhali, F. Ait, Anguner, E. O., Ashkar, H., Backes, M., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernloehr, K., Boettcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Cerruti, M., Chand, T., Chen, A., Chibueze, O., Cotter, G., Cristofari, P., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Atai, A., Dmytriiev, A., Egberts, K., Einecke, S., Ernenwein, J. -P., Feijen, K., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Gabici, S., Gallant, Y. A., Ghafourizadeh, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hoerbe, M., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Huang, Zhiqiu, Jamrozy, M., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzynski, K., Katz, U., Khelifi, B., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Lemiere, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marti-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Nakashima, K., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Poireau, V., Prokhorov, D. A., Puehlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Reville, B., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schafer, J., Schussler, F., Schutte, H. M., Schwanke, U., Shapopi, J. N. S., Simoni, R., Sol, H., Specovius, A., Spencer, S., Stawarz, L., Steinmassl, S., Steppa, C., Sushch, I., Takahashi, T., Tanaka, T., Taylor, A. M., Terrier, R., Tsirou, M., Uchiyama, Y., Unbehaun, T., van Eldik, C., Veh, J., Vink, J., Voelk, H. J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., and Zywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Observations with imaging atmospheric Cherenkov telescopes (IACTs) have enhanced our knowledge of nearby supernova (SN) remnants with ages younger than 500 years by establishing Cassiopeia A and the remnant of Tycho's SN as very-high-energy (VHE) gamma-ray sources. The remnant of Kepler's SN, which is the product of the most recent naked-eye supernova in our Galaxy, is comparable in age to the other two, but is significantly more distant. If the gamma-ray luminosities of the remnants of Tycho's and Kepler's SNe are similar, then the latter is expected to be one of the faintest gamma-ray sources within reach of the current generation IACT arrays. Here we report evidence at a statistical level of 4.6 sigma for a VHE signal from the remnant of Kepler's SN based on deep observations by the High Energy Stereoscopic System (H.E.S.S.) with an exposure of 152 hours. The measured integral flux above an energy of 226 GeV is ~0.3% of the flux of the Crab Nebula. The spectral energy distribution (SED) reveals a gamma-ray emitting component connecting the VHE emission observed with H.E.S.S. to the emission observed at GeV energies with Fermi-LAT. The overall SED is similar to that of the remnant of Tycho's SN, possibly indicating the same non-thermal emission processes acting in both these young remnants of thermonuclear SNe., Comment: Published in Astronomy and Astrophysics. A typo in the normalization constant in Sect. 4 was corrected

Published
2022
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19. Risk Factors Associated with HIV Acquisition in Males Participating in HIV Vaccine Efficacy Trials in South Africa

Author

Malahleha, Mookho, Laher, Fatima, Dilraj, Athmanundh, Smith, Philip, Gray, Glenda E., Grove, Doug, Odhiambo, Jackline A., Andrasik, Michele P., Grunenberg, Nicole A., Moodie, Zoe, Huang, Yunda, Borate, Bhavesh R., Gillespie, Kevin M., Allen, Mary, Atujuna, Millicent, Singh, Nishanta, Kalonji, Dishiki, Meintjes, Graeme, Kotze, Phillip, Bekker, Linda-Gail, and Janes, Holly

Published
2023
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20. Standard of care in advanced HIV disease: review of HIV treatment guidelines in six sub-Saharan African countries

Author

Thomas C. Scheier, Nabila Youssouf, Mosepele Mosepele, Cecilia Kanyama, Olukemi Adekanmbi, Sulaiman Lakoh, Conrad K. Muzoora, Graeme Meintjes, Dominik Mertz, John W. Eikelboom, and Sean Wasserman

Subjects
Advanced HIV disease, Standard of care, Sub-Saharan Africa, REVIVE trial, WHO, Immunologic diseases. Allergy, RC581-607
Abstract

Abstract Background The World Health Organization (WHO) recommends an evidence-based package of care to reduce mortality and morbidity among people with advanced HIV disease (AHD). Adoption of these recommendations by national guidelines in sub-Saharan Africa is poorly documented. We aimed to review national guidelines for AHD management across six selected countries in sub-Saharan Africa for benchmarking against the 2021 WHO recommendations. Methods We reviewed national guidelines from six countries participating in an ongoing randomized controlled trial recruiting people with AHD. We extracted information addressing 18 items of AHD diagnosis and management across the following domains: [1] Definition of AHD, [2] Screening, [3] Prophylaxis, [4] Supportive care, and [5] HIV treatment. Data from national guideline documents were compared to the 2021 WHO consolidated guidelines on HIV and an agreement score was produced to evaluate extent of guideline adoption. Results The distribution of categories of agreement varied for the national documents. Four of the six countries addressed all 18 items (Malawi, Nigeria, Sierra Leone, Uganda). Overall agreement with the WHO 2021 guidelines ranged from 9 to 15.5 out of 18 possible points: Malawi 15.5 points, Nigeria, and Sierra Leone 14.5 points, South Africa 13.5 points, Uganda 13.0 points and Botswana with 9.0 points. Most inconsistencies were reported for the delay of antiretroviral therapy (ART) in presence of opportunistic diseases. None of the six national guidelines aligned with WHO recommendations around ART timing in patients with tuberculosis. Agreement correlated with the year of publication of the national guideline. Conclusion National guidelines addressing the care of advanced HIV disease in sub-Saharan Africa are available. Besides optimal timing for start of ART in presence of tuberculosis, most national recommendations are in line with the 2021 WHO standards.

Published
2023
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21. Probing the Non-thermal Emission Geometry of AR Sco via Optical Phase-Resolved Polarimetry

Author

Plessis, Louis du, Venter, Christo, Wadiasingh, Zorawar, Harding, Alice K., Buckley, David A. H., Potter, Stephen B., and Meintjes, P. J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

AR Sco is a binary system that contains a white and red dwarf. The rotation rate of the white dwarf has been observed to slow down, analogous to rotation-powered radio pulsars; it has thus been dubbed a "white dwarf pulsar". We previously fit the traditional radio pulsar rotating vector model to the linearly polarised optical data from this source, constraining the system geometry as well as the white dwarf mass. Using a much more extensive dataset, we now explore the application of the same model to binary phase-resolved optical polarimetric data, thought to be the result of non-thermal synchrotron radiation, and derive the magnetic inclination angle $\alpha$ and the observer angle $\zeta$ at different orbital phases. We obtain a $\sim 10^{\circ}$ variation in $\alpha$ and $\sim 30^{\circ}$ variation in $\zeta$ over the orbital period. The variation patterns in these two parameters is robust, regardless of the binning and epoch of data used. We speculate that the observer is detecting radiation from an asymmetric emission region that is a stable structure over several orbital periods. The success of this simple model lastly implies that the pitch angles of the particles are small and the pulsed, non-thermal emission originates relatively close to the white dwarf surface., Comment: 13 pages, 14 figures, accepted by MNRAS

Published
2021
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22. H.E.S.S. follow-up observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo

Author

collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Batzofin, R., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-AtaÏ, A., Egberts, K., Ernenwein, J. -P., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Gabici, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hinton, J. A., Hörbe, M., Hofmann, W., Holch, T. L., Holler, M., Huang, Zhiqiu, Huber, D., Jamrozy, M., Jankowsky, F., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khélifi, B., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kundu, A., Lamanna, G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A. Priyana, O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Parsons, R. D., Peron, G., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Renaud, M., Rieger, F., Rowell, G., Rudak, B., Ricarte, H. Rueda, Velasco, E. Ruiz, Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Shapopi, J. N. S., Sinha, A., Sol, H., Specovius, A., Spencer, S., Stawarz, L., Steinmassl, S., Steppa, C., Sun, L., Takahashi, T., Tanaka, T., Terrier, R., Thorpe-Morgan, C., Tsirou, M., Tsuji, N., Uchiyama, Y., van Eldik, C., Veh, J., Vink, J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Zacharias, M., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zouari, S., and Zywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the observations of four well-localized binary black hole (BBH) mergers by the High Energy Stereoscopic System (H.E.S.S.) during the second and third observing runs of Advanced LIGO and Advanced Virgo, O2 and O3. H.E.S.S. can observe $\mathrm{20\,deg^2}$ of the sky at a time and follows up gravitational-wave (GW) events by ``tiling'' localization regions to maximize the covered localization probability. During O2 and O3, H.E.S.S. observed large portions of the localization regions, between 35\% and 75\%, for four BBH mergers (GW170814, GW190512\_180714, GW190728\_064510, and S200224ca). For these four GW events, we find no significant signal from a pointlike source in any of the observations, and set upper limits on the very high energy ($>$100 GeV) $\gamma$-ray emission. The 1-10 TeV isotropic luminosity of these GW events is below $10^{45}$ erg s$^{-1}$ at the times of the H.E.S.S. observations, around the level of the low-luminosity GRB 190829A. Assuming no changes are made to how follow-up observations are conducted, H.E.S.S. can expect to observe over 60 GW events per year in the fourth GW observing run, O4, of which eight would be observable with minimal latency.

Published
2021
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23. A crowd of BashTheBug volunteers reproducibly and accurately measure the minimum inhibitory concentrations of 13 antitubercular drugs from photographs of 96-well broth microdilution plates

Author

Fowler, Philip W, Wright, Carla, Spiers, Helen, Zhu, Tingting, Baeten, Elisabeth ML, Hoosdally, Sarah W, Cruz, Ana L Gibertoni, Roohi, Aysha, Kouchaki, Samaneh, Walker, Timothy M, Peto, Timothy EA, Miller, Grant, Lintott, Chris, Clifton, David, Crook, Derrick W, Walker, A Sarah, Barilar, Ivan, Battaglia, Simone, Borroni, Emanuele, Brandao, Angela Pires, Brankin, Alice, Cabibbe, Andrea Maurizio, Carter, Joshua, Cirillo, Daniela Maria, Claxton, Pauline, Clifton, David A, Cohen, Ted, Coronel, Jorge, Earle, Sarah G, Escuyer, Vincent, Ferrazoli, Lucilaine, Gao, George F, Gardy, Jennifer, Gharbia, Saheer, Ghisi, Kelen Teixeira, Ghodousi, Arash, Cruz, Ana Luıza Gibertoni, Grazian, Clara, Guthrie, Jennifer L, He, Wencong, Hoffmann, Harald, Hoosdally, Sarah J, Hunt, Martin, Iqbal, Zamin, Ismail, Nazir Ahmed, Jarrett, Lisa, Joseph, Lavania, Jou, Ruwen, Kambli, Priti, Knaggs, Jeff, Koch, Anastasia, Kohlerschmidt, Donna, Lachapelle, Alexander S, Lalvani, Ajit, Lapierre, Simon Grandjean, Laurenson, Ian F, Letcher, Brice, Lin, Wan-Hsuan, Liu, Chunfa, Liu, Dongxin, Malone, Kerri M, Mandal, Ayan, Matias, Daniela, Meintjes, Graeme, Mendes, Flavia Freitas, Merker, Matthias, Mihalic, Marina, Millard, James, Miotto, Paolo, Mistry, Nerges, Moore, David, Dreyer, Viola, Chetty, Darren, Musser, Kimberlee A, Ngcamu, Dumisani, Nhung, Hoang Ngoc, Grandjean, Louis, Nilgiriwala, Kayzad Soli, Nimmo, Camus, Okozi, Nana, Oliveira, Rosangela Siqueira, Omar, Shaheed Vally, Paton, Nicholas, Pinhata, Juliana Maira Watanabe, Plesnik, Sara, Puyen, Zully M, Rabodoarivelo, Marie Sylvianne, Rakotosamimanana, Niaina, Rancoita, Paola MV, Rathod, Priti, Robinson, Esther, Rodger, Gillian, Rodrigues, Camilla, Rodwell, Timothy C, and Santos-Lazaro, David

Subjects
Biological Sciences, Biomedical and Clinical Sciences, Clinical Sciences, Emerging Infectious Diseases, Infectious Diseases, Prevention, Antimicrobial Resistance, 5.1 Pharmaceuticals, Development of treatments and therapeutic interventions, Infection, Good Health and Well Being, Antitubercular Agents, Humans, Microbial Sensitivity Tests, Mycobacterium tuberculosis, Tuberculosis, Volunteers, Zooniverse Volunteer Community, CRyPTIC Consortium, M. tuberculosis, antibiotics, citizen science, clinical microbiology, infectious disease, microbiology, tuberculosis, Biochemistry and Cell Biology, Biological sciences, Biomedical and clinical sciences, Health sciences
Abstract

Tuberculosis is a respiratory disease that is treatable with antibiotics. An increasing prevalence of resistance means that to ensure a good treatment outcome it is desirable to test the susceptibility of each infection to different antibiotics. Conventionally, this is done by culturing a clinical sample and then exposing aliquots to a panel of antibiotics, each being present at a pre-determined concentration, thereby determining if the sample isresistant or susceptible to each sample. The minimum inhibitory concentration (MIC) of a drug is the lowestconcentration that inhibits growth and is a more useful quantity but requires each sample to be tested at a range ofconcentrations for each drug. Using 96-well broth micro dilution plates with each well containing a lyophilised pre-determined amount of an antibiotic is a convenient and cost-effective way to measure the MICs of several drugs at once for a clinical sample. Although accurate, this is still an expensive and slow process that requires highly-skilled and experienced laboratory scientists. Here we show that, through the BashTheBug project hosted on the Zooniverse citizen science platform, a crowd of volunteers can reproducibly and accurately determine the MICs for 13 drugs and that simply taking the median or mode of 11-17 independent classifications is sufficient. There is therefore a potential role for crowds to support (but not supplant) the role of experts in antibiotic susceptibility testing.

Published
2022

24. Searching for TeV gamma-ray emission from SGR\,1935+2154 during its 2020 X-ray and radio bursting phase

Author

Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Anguner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlohr, K., Bi, B., Bottcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Brun, P., Bryan, M., Buchele, M., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Carosi, A., Casanova, S., Chambery, P., Chand, T., Chandra, S., Chen, A., Cotter, G., lo, M. Cury, Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Plessis, L. Du, Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Ghafourizade, S., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hattingh, S., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horbe, M., Horns, D., Huang, Z., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Mezek, G. Kukec, Kundu, A., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Stum, S. Le, Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Reville, B., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spackman, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Thorpe-Morgan, C., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., deWilt, P., Wong, Yu Wun, Yassin, H., Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., and Żywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Magnetar hyperflares are the most plausible explanation for fast radio bursts (FRB) -- enigmatic powerful radio pulses with durations of several milliseconds and high brightness temperatures. The first observational evidence for this scenario was obtained in 2020 April when a FRB was detected from the direction of the Galactic magnetar and soft gamma-ray repeater SGR\,1935+2154. The FRB was preceded by two gamma-ray outburst alerts by the BAT instrument aboard the Swift satellite, which triggered follow-up observations by the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. has observed SGR\,1935+2154 for 2 hr on 2020 April 28. The observations are coincident with X-ray bursts from the magnetar detected by INTEGRAL and Fermi-GBM, thus providing the first very high energy (VHE) gamma-ray observations of a magnetar in a flaring state. High-quality data acquired during these follow-up observations allow us to perform a search for short-time transients. No significant signal at energies $E>0.6$~TeV is found and upper limits on the persistent and transient emission are derived. We here present the analysis of these observations and discuss the obtained results and prospects of the H.E.S.S. follow-up program for soft gamma-ray repeaters., Comment: Received 2021 June 13; accepted 2021 June 28; published 2021 September 29

Published
2021
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25. Observation of the gamma-ray binary HESS J0632+057 with the H.E.S.S., MAGIC, and VERITAS telescopes

Author

Adams, C. B., Benbow, W., Brill, A., Buckley, J. H., Capasso, M., Chromey, A. J., Errando, M., Falcone, A., Farrell, K. A., Feng, Q., Finley, J P., Foote, G., Fortson, L., Furniss, A., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hona, B., Humensky, T. B., Jin, W., Kaaret, P., Kertzman, M., Kieda, D., Kleiner, T. K., Krennrich, F., Kumar, S., Lang, M. J., Lundy, M., Maier, G., McGrath, C. E., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Patel, S., Pfrang, K., Pichel, A., Pohl, M., Prado, R. R., Quinn, J., Ragan, K., Reynolds, P. T., Ribeiro, D., Roache, E., Rovero, A. C., Ryan, J. L., Santander, M., Schlenstedt, S., Sembroski, G. H., Shang, R., Tak, D., Vassiliev, V. V., Weinstein, A., Williams, D. A., Williamson, T. J., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., Batković, I., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bökenkamp, H., Bonnol, G., Bošnjak, Ž., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Espiñeira, E. Do Souto, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Fukazawa, Y., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Ishio, K., Iwamura, Y., Martínez, I. Jiménez, Jormanainen, J., Jouvin, L., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Linhoff, L., Lombardi, S., Longo, F., López-Coto, R., López-Moya, M., López-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Menchiari, S., Mender, S., Mićanović, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Nakamori, T., Nava, L., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Nozaki, K. Noda S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., Peñil, P., Persic, M., Pihet, M., Moroni, P. G. Prada, Prandini, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Spolon, D. Sobczynska A., Stamerra, A., Strišković, J., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Takeishi, R., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Yamamoto, T., Zarić, D., Abdalla, H., Aharonian, F., Ait-Benkhali, F., Anguener, O., Arcaro, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Batzofin, R., Becherini, Y., Berge, D., Bernloehr, K., Bi, B., Boettcher, M., Boisson, C., Bolmont, J., de Bony, M., Breuhaus, M., Brose, R., Brun, F., Bulik, T., Caroff, S., Casanova, S., Chand, T., Chen, A., Cotter, G., Mbarubucyeye, J. Damascene, Devin, J., Djannati-Atai, A., Egberts, K., Ernenwein, J., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Fuessling, M., Funk, S., Gabici, S., Giavitto, G., Glawion, D., Glicenstein, J., Grondin, M., Hinton, J., Hofmann, W., Holch, T., Holler, M., Horns, D., Huang, Z., Jamrozy, M., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzynski, K., Khelifi, B., Komin, N., Kosack, K., Kostunin, D., Stum, S. Le, Lemiere, A., Lenain, J., Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Marti'i-Devesa, G., Marx, R., Maurin, G., Meintjes, P., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moulin, E., Muller, J., Murach, T., de Naurois, M., Nayerhoda, A., Niemiec, J., Noel, A., O'Brien, P., Ohm, S., Olivera-Nieto, L., de Ona-Wilhelmi, E., Ostrowski, M., Panny, S., Panter, M., Parsons, D., Peron, G., Poireau, V., Prokhorov, D., Prokoph, H., Puehlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Velasco, E. Ruiz, Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D., Santangelo, A., Sasaki, M., Schuessler, F., Schutte, H., Schwanke, U., Senniappan, M., Shapopi, J., Simoni, R., Sol, H., Specovius, A., Spencer, S., Steenkamp, R., Steinmassl, S., Sun, L., Takahashi, T., Tanaka, T., Terrier, R., Tsuji, N., Uchiyama, Y., van Eldik, C., van Soelen, B., Veh, J., Venter, C., Vink, J., Wagner, S., White, R., Wierzcholska, A., Wong, Y. W., Zacharias, M., Zargaryan, D., Zdziarski, A., Zech, A., Zhu, S., Zouari, S., Zywucka, N., Moritani, Y., and Torres, D. F.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The results of gamma-ray observations of the binary system HESS J0632+057 collected during 450 hours over 15 years, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the H{\alpha} emission line. A significant detection of the modulation of the VHE gamma-ray fluxes with a period of 316.7+-4.4 days is reported, consistent with the period of 317.3+-0.7 days obtained with a refined analysis of X-ray data. The analysis of data of four orbital cycles with dense observational coverage reveals short timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over the time scale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but can not find any correlation of optical H{\alpha} parameters with X-ray or gamma-ray energy fluxes in simultaneous observations. The key finding is that the emission of HESS J0632+057 in the X-ray and gamma-ray energy bands is highly variable on different time scales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems., Comment: Accepted for publication by The Astrophysical Journal

Published
2021
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26. Artificial Neural Networks for cosmic gamma-ray propagation in the Universe

Author

Singh, K K, Dhar, V K, and Meintjes, P J

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We explore the potential of an artificial neural network (ANN) based method intelligence to probe the propagation of cosmic $\gamma$-ray photons in the extragalactic Universe. The journey of $\gamma$-rays emitted from a distant source like blazar to the observer at the Earth is impeded by the absorption through the interaction with the extragalactic background light (EBL), leading to an electron-positron pair production. This process dominates for gamma ray photons with energy above 10 GeV propagating over the cosmological distances. The effect of $\gamma$-ray attenuation is characterized by a physical quantity called \emph{optical depth}, which strongly depends on the $\gamma$-ray photon energy, redshift of the source, and density of the EBL photons. We estimate the optical depth values for $\gamma$-ray energies above 10 GeV emitted from the sources at redshifts in the range 0.01 to 1 using three different and most promising EBL models. These optical depth estimates are randomly divided into two data sets for training and testing of the ANN using energy, redshift as inputs and optical depth as output. The optimization of ANN-performance for each EBL model employs standard back-propagation (BP) and radial-basis function (RBF) algorithms. The performance of the ANN model using the RBF is found to be superior to the BP method. In particular, the RBF-ANN with 40 neurons in the hidden layer corresponding to the EBL model proposed by Finke et al. (2010) shows the best performance for the propagation of $\gamma$-rays in the Universe., Comment: 23 Pages, 6 Tables, 6 Figures, Accepted for Publication in New Astronomy Journal

Published
2021
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27. Uniform scrambles on graphs

Author

Cenek, Lisa, Ferguson, Lizzie, Gebre, Eyobel, Marcussen, Cassandra, Meintjes, Jason, Morrison, Ralph, Ostermeyer, Liz, and Ramakrishna, Shefali

Subjects
Mathematics - Combinatorics, Mathematics - Algebraic Geometry, 05C57, 14T99
Abstract

A scramble on a connected multigraph is a collection of connected subgraphs that generalizes the notion of a bramble. The maximum order of a scramble, called the scramble number of a graph, was recently developed as a tool for lower bounding divisorial gonality. We present results on the scramble of all connected subgraphs with a fixed number of vertices, using these to calculate scramble number and gonality both for large families of graphs, and for specific examples like the $4$- and $5$-dimensional hypercube graphs. We also study the computational complexity of the egg-cut number of a scramble., Comment: 13 pages, 9 figures

Published
2021

28. LMC N132D: A mature supernova remnant with a power-law gamma-ray spectrum extending beyond 8 TeV

Author

Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzynski, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., and Żywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We analyzed 252 hours of High Energy Stereoscopic System (H.E.S.S.) observations towards the supernova remnant (SNR) LMC N132D that were accumulated between December 2004 and March 2016 during a deep survey of the Large Magellanic Cloud, adding 104 hours of observations to the previously published data set to ensure a > 5 sigma detection. To broaden the gamma-ray spectral coverage required for modeling the spectral energy distribution, an analysis of Fermi-LAT Pass 8 data was also included. We unambiguously detect N132D at very high energies (VHE) with a significance of 5.7 sigma. We report the results of a detailed analysis of its spectrum and localization based on the extended H.E.S.S. data set. The joint analysis of the extended H.E.S.S and Fermi-LAT data results in a spectral energy distribution in the energy range from 1.7 GeV to 14.8 TeV, which suggests a high luminosity of N132D at GeV and TeV energies. We set a lower limit on a gamma-ray cutoff energy of 8 TeV with a confidence level of 95%. The new gamma-ray spectrum as well as multiwavelength observations of N132D when compared to physical models suggests a hadronic origin of the VHE gamma-ray emission. SNR N132D is a VHE gamma-ray source that shows a spectrum extending to the VHE domain without a spectral cutoff at a few TeV, unlike the younger oxygen-rich SNR Cassiopeia A. The gamma-ray properties of N132D may be affected by an interaction with a nearby molecular cloud that partially lies inside the 95% confidence region of the source position. [Abridged], Comment: Accepted for publication in Astronomy & Astrophysics

Published
2021
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33. Virologic outcomes with tenofovir-lamivudine-dolutegravir in adults failing PI-based second-line ART

Author

Ying Zhao, Jacqueline Voget, Isaac Singini, Zaayid Omar, Vanessa Mudaly, Andrew Boulle, Gary Maartens, and Graeme Meintjes

Subjects
antiretroviral therapy, dolutegravir, hiv, virologic failure, third-line., Public aspects of medicine, RA1-1270, Infectious and parasitic diseases, RC109-216
Abstract

Background: In South African antiretroviral guidelines, selected patients failing second-line protease inhibitor (PI)-based therapy qualify for genotypic resistance testing – those with PI resistance receive darunavir-based third-line regimens; those without PI resistance continue current regimen with adherence support. The Western Cape province, from September 2020, implemented a strategy of tenofovir-lamivudine-dolutegravir (TLD) for patients, provided there was no tenofovir resistance, irrespective of PI resistance. Objectives: To evaluate virologic outcomes with TLD among adults failing second-line PI regimens with no tenofovir resistance. Method: An observational cohort study comparing outcomes in patients switched to TLD with those continuing the same PI or switched to darunavir-based regimens. Follow-up was until virologic suppression (HIV-1 RNA 400 copies/mL), or at the point of censoring. Results: One hundred and thirty-three patients switched to TLD, 101 to darunavir-based regimens, and 121 continued with the same PI. By 12 months, among patients with PI resistance, 42/47 (89%) in the TLD group had HIV-1 RNA 400 copies/mL compared to 91/99 (92%) in the darunavir group (hazard ratio, 1.11; 95% confidence interval, 0.77–1.60). In patients without PI resistance, 66/86 (77%) in the TLD group had HIV-1 RNA 400 copies/mL compared to 42/120 (35%) in those continuing with the same PI (hazard ratio, 4.03; 95% confidence interval, 2.71–5.98). Two patients receiving TLD developed virologic failure with high-level dolutegravir resistance. Conclusion: Amongst patients failing second-line PI with no PI resistance, switching to TLD was associated with higher virologic suppression, likely due to improved adherence. Virologic outcomes were similar in patients with PI resistance switched to darunavir-based regimens or TLD.

Published
2024
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34. Reduced white matter maturation in the central auditory system of children living with HIV

Author

Joanah Madzime, Marcin Jankiewicz, Ernesta M. Meintjes, Peter Torre, Barbara Laughton, Andre J. W. van der Kouwe, and Martha Holmes

Subjects
central auditory system, HIV, diffusion tensor imaging, auditory working memory, graph theory, Neurology. Diseases of the nervous system, RC346-429
Abstract

IntroductionSchool-aged children experience crucial developmental changes in white matter (WM) in adolescence. The human immunodeficiency virus (HIV) affects neurodevelopment. Children living with perinatally acquired HIV (CPHIVs) demonstrate hearing and neurocognitive impairments when compared to their uninfected peers (CHUUs), but investigations into the central auditory system (CAS) WM integrity are lacking. The integration of the CAS and other brain areas is facilitated by WM fibers whose integrity may be affected in the presence of HIV, contributing to neurocognitive impairments.MethodsWe used diffusion tensor imaging (DTI) tractography to map the microstructural integrity of WM between CAS regions, including the lateral lemniscus and acoustic radiation, as well as between CAS regions and non-auditory regions of 11-year-old CPHIVs. We further employed a DTI-based graph theoretical framework to investigate the nodal strength and efficiency of the CAS and other brain regions in the structural brain network of the same population. Finally, we investigated associations between WM microstructural integrity outcomes and neurocognitive outcomes related to auditory and language processing. We hypothesized that compared to the CHUU group, the CPHIV group would have lower microstructural in the CAS and related regions.ResultsOur analyses showed higher mean diffusivity (MD), a marker of axonal maturation, in the lateral lemniscus and acoustic radiations, as well as WM between the CAS and non-auditory regions predominantly in frontotemporal areas. Most affected WM connections also showed higher axial and radial diffusivity (AD and RD, respectively). There were no differences in the nodal properties of the CAS regions between groups. The MD of frontotemporal and subcortical WM-connected CAS regions, including the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and internal capsule showed negative associations with sequential processing in the CPHIV group but not in the CHUU group.DiscussionThe current results point to reduced axonal maturation in WM, marked by higher MD, AD, and RD, within and from the CAS. Furthermore, alterations in WM integrity were associated with sequential processing, a neurocognitive marker of auditory working memory. Our results provide insights into the microstructural integrity of the CAS and related WM in the presence of HIV and link these alterations to auditory working memory.

Published
2024
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35. Pharmacokinetics of antitubercular drugs in patients hospitalized with HIV-associated tuberculosis: a population modeling analysis [version 3; peer review: 1 approved, 2 approved with reservations]

Author

Helen McIlleron, Lubbe Wiesner, Charlotte Schutz, Robert J. Wilkinson, Graeme Meintjes, Noha Abdelgawad, David Barr, Maxwell Chirehwa, Saskia Janssen, Amy Ward, Muki Shey, Rosie Burton, Gary Maartens, and Paolo Denti

Subjects
rifampicin, isoniazid, pyrazinamide, hospitalization, tuberculosis, eng, Medicine, Science
Abstract

Background Early mortality among hospitalized HIV-associated tuberculosis (TB/HIV) patients is high despite treatment. The pharmacokinetics of rifampicin, isoniazid, and pyrazinamide were investigated in hospitalized TB/HIV patients and a cohort of outpatients with TB (with or without HIV) to determine whether drug exposures differed between groups. Methods Standard first-line TB treatment was given daily as per national guidelines, which consisted of oral 4-drug fixed-dose combination tablets containing 150 mg rifampicin, 75 mg isoniazid, 400 mg pyrazinamide, and 275 mg ethambutol. Plasma samples were drawn on the 3rd day of treatment over eight hours post-dose. Rifampicin, isoniazid, and pyrazinamide in plasma were quantified and NONMEM® was used to analyze the data. Results Data from 60 hospitalized patients (11 of whom died within 12 weeks of starting treatment) and 48 outpatients were available. Median (range) weight and age were 56 (35 - 88) kg, and 37 (19 - 77) years, respectively. Bioavailability and clearance of the three drugs were similar between TB/HIV hospitalized and TB outpatients. However, rifampicin’s absorption was slower in hospitalized patients than in outpatients; mean absorption time was 49.9% and 154% more in hospitalized survivors and hospitalized deaths, respectively, than in outpatients. Higher levels of conjugated bilirubin correlated with lower rifampicin clearance. Isoniazid’s clearance estimates were 25.5 L/h for fast metabolizers and 9.76 L/h for slow metabolizers. Pyrazinamide’s clearance was more variable among hospitalized patients. The variability in clearance among patients was 1.70 and 3.56 times more for hospitalized survivors and hospitalized deaths, respectively, than outpatients. Conclusions We showed that the pharmacokinetics of first-line TB drugs are not substantially different between hospitalized TB/HIV patients and TB (with or without HIV) outpatients. Hospitalized patients do not seem to be underexposed compared to their outpatient counterparts, as well as hospitalized patients who survived vs who died within 12 weeks of hospitalization.

Published
2024
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36. Montreal Cognitive Assessment test: Psychometric analysis of a South African workplace sample

Author

Charles H. van Wijk, Willem A.J. Meintjes, and Chris J.B. Muller

Subjects
cognition, dimensionality, grey-zone thresholds, language, measurement invariance, screening, validity, Psychology, BF1-990
Abstract

The Montreal Cognitive Assessment (MoCA) test is a widely used tool to screen for mild neurocognitive impairment. However, its structural validity has not been fully described in South Africa. The study aimed to replicate and extend earlier work with South African samples, to provide an expanded description of the psychometric properties of the MoCA. The study examined the MoCA in a sample of neurocognitively healthy working adults (N = 402) and individuals diagnosed with mild neurocognitive disorders (N = 42); both groups reported good English proficiency. Analysis included general scale descriptions, and structural and discriminant validity. Age and language, but not gender, influenced MoCA scores, with mean total scores of healthy individuals falling below the universal cut-off. Structural analysis showed that a multidimensional model with a higher-order general factor fit the data well, and measurement invariance for gender and language was confirmed. Discriminant validity was supported, and receiver operating characteristics curve analysis illustrated the potential for grey-zone lower and upper thresholds to identify risk. Contribution: This study replicated previous findings on the effects of age, language and gender, and challenged the universal application of ≤ 26 as cut-off for cognitive impairment indiscriminately across groups or contexts. It emphasised the need for context-specific adaptation in cognitive assessments, especially for non-English first language speakers, to enhance practical utility. Novel to this study, it extended knowledge on the structural validity of the test and introduced grey-zone scores as a potential guide to the identification of risk in resource-restricted settings.

Published
2024
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37. The 2021 WHO catalogue of Mycobacterium tuberculosis complex mutations associated with drug resistance: a genotypic analysis

Author

Walker, Timothy M, Miotto, Paolo, Köser, Claudio U, Fowler, Philip W, Knaggs, Jeff, Iqbal, Zamin, Hunt, Martin, Chindelevitch, Leonid, Farhat, Maha R, Cirillo, Daniela Maria, Comas, Iñaki, Posey, James, Omar, Shaheed V, Peto, Timothy EA, Suresh, Anita, Uplekar, Swapna, Laurent, Sacha, Colman, Rebecca E, Nathanson, Carl-Michael, Zignol, Matteo, Walker, Ann Sarah, Crook, Derrick W, Ismail, Nazir, Rodwell, Timothy C, Consortium, the SeqTreat Consortium CRyPTIC, Walker, A Sarah, Steyn, Adrie JC, Lalvani, Ajit, Baulard, Alain, Christoffels, Alan, Mendoza-Ticona, Alberto, Trovato, Alberto, Skrahina, Alena, Lachapelle, Alexander S, Brankin, Alice, Piatek, Amy, Cruz, Ana Gibertoni, Koch, Anastasia, Cabibbe, Andrea Maurizio, Spitaleri, Andrea, Brandao, Angela P, Chaiprasert, Angkana, Barbova, Anna, Van Rie, Annelies, Ghodousi, Arash, Bainomugisa, Arnold, Mandal, Ayan, Roohi, Aysha, Javid, Babak, Zhu, Baoli, Letcher, Brice, Rodrigues, Camilla, Nimmo, Camus, NATHANSON, Carl-Michael, Duncan, Carla, Coulter, Christopher, Utpatel, Christian, Liu, Chunfa, Grazian, Clara, Kong, Clare, Wilson, Daniel J, Matias, Daniela, Jorgensen, Danielle, Zimenkov, Danila, Chetty, Darren, Moore, David AJ, Clifton, David A, van Soolingen, Dick, Liu, Dongxin, Kohlerschmidt, Donna, Barreira, Draurio, Ngcamu, Dumisani, Lazaro, Elias David Santos, Kelly, Ellis, Borroni, Emanuele, Roycroft, Emma, Andre, Emmanuel, Böttger, Erik C, Robinson, Esther, Menardo, Fabrizio, Mendes, Flavia F, Jamieson, Frances B, Coll, Francesc, Gao, George Fu, Kasule, George W, Rossolini, Gian Maria, Rodger, Gillian, Smith, E Grace, Meintjes, Graeme, Thwaites, Guy, Hoffmann, Harald, Albert, Heidi, Cox, Helen, Laurenson, Ian F, and Arandjelovic, Irena

Subjects
Biological Sciences, Biomedical and Clinical Sciences, Genetics, Microbiology, Clinical Sciences, Tuberculosis, Infectious Diseases, Rare Diseases, Antimicrobial Resistance, Orphan Drug, Development of treatments and therapeutic interventions, 5.1 Pharmaceuticals, Infection, Good Health and Well Being, Antitubercular Agents, Drug Resistance, Ethambutol, Microbial Sensitivity Tests, Mutation, Mycobacterium tuberculosis, World Health Organization, CRyPTIC Consortium, Seq&Treat Consortium, Immunology, Medical microbiology
Abstract

BackgroundMolecular diagnostics are considered the most promising route to achieving rapid, universal drug susceptibility testing for Mycobacterium tuberculosiscomplex (MTBC). We aimed to generate a WHO endorsed catalogue of mutations to serve as a global standard for interpreting molecular information for drug resistance prediction.MethodsA candidate gene approach was used to identify mutations as associated with resistance, or consistent with susceptibility, for 13 WHO endorsed anti-tuberculosis drugs. 38,215 MTBC isolates with paired whole-genome sequencing and phenotypic drug susceptibility testing data were amassed from 45 countries. For each mutation, a contingency table of binary phenotypes and presence or absence of the mutation computed positive predictive value, and Fisher's exact tests generated odds ratios and Benjamini-Hochberg corrected p-values. Mutations were graded as Associated with Resistance if present in at least 5 isolates, if the odds ratio was >1 with a statistically significant corrected p-value, and if the lower bound of the 95% confidence interval on the positive predictive value for phenotypic resistance was >25%. A series of expert rules were applied for final confidence grading of each mutation.Findings15,667 associations were computed for 13,211 unique mutations linked to one or more drugs. 1,149/15,667 (7·3%) mutations were classified as associated with phenotypic resistance and 107/15,667 (0·7%) were deemed consistent with susceptibility. For rifampicin, isoniazid, ethambutol, fluoroquinolones, and streptomycin, the mutations' pooled sensitivity was >80%. Specificity was over 95% for all drugs except ethionamide (91·4%), moxifloxacin (91·6%) and ethambutol (93·3%). Only two resistance mutations were classified for bedaquiline, delamanid, clofazimine, and linezolid as prevalence of phenotypic resistance was low for these drugs.InterpretationThis first WHO endorsed catalogue of molecular targets for MTBC drug susceptibility testing provides a global standard for resistance interpretation. Its existence should encourage the implementation of molecular diagnostics by National Tuberculosis Programmes.FundingUNITAID, Wellcome, MRC, BMGF.

Published
2022

38. Tuberculosis screening among ambulatory people living with HIV: a systematic review and individual participant data meta-analysis

Author

Dhana, Ashar, Hamada, Yohhei, Kengne, Andre P, Kerkhoff, Andrew D, Rangaka, Molebogeng X, Kredo, Tamara, Baddeley, Annabel, Miller, Cecily, Singh, Satvinder, Hanifa, Yasmeen, Grant, Alison D, Fielding, Katherine, Affolabi, Dissou, Merle, Corinne S, Wachinou, Ablo Prudence, Yoon, Christina, Cattamanchi, Adithya, Hoffmann, Christopher J, Martinson, Neil, Mbu, Eyongetah Tabenyang, Sander, Melissa S, Balcha, Taye T, Skogmar, Sten, Reeve, Byron WP, Theron, Grant, Ndlangalavu, Gcobisa, Modi, Surbhi, Cavanaugh, Joseph, Swindells, Susan, Chaisson, Richard E, Khan, Faiz Ahmad, Howard, Andrea A, Wood, Robin, Thit, Swe Swe, Kyi, Mar Mar, Hanson, Josh, Drain, Paul K, Shapiro, Adrienne E, Kufa, Tendesayi, Churchyard, Gavin, Nguyen, Duc T, Graviss, Edward A, Bjerrum, Stephanie, Johansen, Isik S, Gersh, Jill K, Horne, David J, LaCourse, Sylvia M, Al-Darraji, Haider Abdulrazzaq Abed, Kamarulzaman, Adeeba, Kempker, Russell R, Tukvadze, Nestani, Barr, David A, Meintjes, Graeme, and Maartens, Gary

Subjects
Biomedical and Clinical Sciences, Clinical Sciences, Health Sciences, Clinical Research, Rare Diseases, Tuberculosis, Infectious Diseases, HIV/AIDS, 4.2 Evaluation of markers and technologies, Evaluation of treatments and therapeutic interventions, Detection, screening and diagnosis, 6.1 Pharmaceuticals, Infection, Good Health and Well Being, Adolescent, Adult, Antibiotics, Antitubercular, Child, Cross-Sectional Studies, HIV Infections, Humans, Mycobacterium tuberculosis, Prospective Studies, Rifampin, Sensitivity and Specificity, Tuberculosis, Pulmonary, Medical Microbiology, Public Health and Health Services, Microbiology, Clinical sciences, Medical microbiology, Epidemiology
Abstract

BackgroundThe WHO-recommended tuberculosis screening and diagnostic algorithm in ambulatory people living with HIV is a four-symptom screen (known as the WHO-recommended four symptom screen [W4SS]) followed by a WHO-recommended molecular rapid diagnostic test (eg Xpert MTB/RIF [hereafter referred to as Xpert]) if W4SS is positive. To inform updated WHO guidelines, we aimed to assess the diagnostic accuracy of alternative screening tests and strategies for tuberculosis in this population.MethodsIn this systematic review and individual participant data meta-analysis, we updated a search of PubMed (MEDLINE), Embase, the Cochrane Library, and conference abstracts for publications from Jan 1, 2011, to March 12, 2018, done in a previous systematic review to include the period up to Aug 2, 2019. We screened the reference lists of identified pieces and contacted experts in the field. We included prospective cross-sectional, observational studies and randomised trials among adult and adolescent (age ≥10 years) ambulatory people living with HIV, irrespective of signs and symptoms of tuberculosis. We extracted study-level data using a standardised data extraction form, and we requested individual participant data from study authors. We aimed to compare the W4SS with alternative screening tests and strategies and the WHO-recommended algorithm (ie, W4SS followed by Xpert) with Xpert for all in terms of diagnostic accuracy (sensitivity and specificity), overall and in key subgroups (eg, by antiretroviral therapy [ART] status). The reference standard was culture. This study is registered with PROSPERO, CRD42020155895.FindingsWe identified 25 studies, and obtained data from 22 studies (including 15 666 participants; 4347 [27·7%] of 15 663 participants with data were on ART). W4SS sensitivity was 82% (95% CI 72-89) and specificity was 42% (29-57). C-reactive protein (≥10 mg/L) had similar sensitivity to (77% [61-88]), but higher specificity (74% [61-83]; n=3571) than, W4SS. Cough (lasting ≥2 weeks), haemoglobin (

Published
2022

39. TeV emission of Galactic plane sources with HAWC and H.E.S.S

Author

Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., Brien, P. O, Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zmija, A., Zorn, J., Zouari, S., Żywucka, N., Albert, A., Alfaro, R., Alvarez, C., Arteaga-Velázquez, J. C., Arunbabu, K. P., Rojas, D. Avila, Belmont-Moreno, E., BenZvi, S. Y., Brisbois, C., Caballero-Mora, K. S., Capistrán, T., Carramiñana, A., Casanova, S., Cotti, U., Cotzomi, J., de León, S. Coutiño, De la Fuente, E., de León, C., Hernandez, R. Diaz, Díaz-Vélez, J. C., Dingus, B. L., DuVernois, M. A., Durocher, M., Ellsworth, R. W., Engel, K., Espinoza, C., Fan, K. L., Alonso, M. Fernández, Fraija, N., Galván-Gámez, A., Garcia, D., García-González, J. A., Garfias, F., Giacinti, G., González, M. M., Goodman, J. A., Harding, J. P., Hernandez, S., Hona, B., Huang, D., Hueyotl-Zahuantitla, F., Hüntemeyer, P., Iriarte, A., Jardin-Blicq, A., Joshi, V., Kieda, D., Lee, W. H., Vargas, H. León, Linnemann, J. T., Longinotti, A. L., Luis-Raya, G., López-Coto, R., Malone, K., Martinez, O., Martinez-Castellanos, I., Martínez-Castro, J., Matthews, J. A., Miranda-Romagnoli, P., Morales-Soto, J. A., Moreno, E., Mostafá, M., Nellen, L., Newbold, M., Nisa, M. U., Noriega-Papaqui, R., Omodei, N., Peisker, A., Araujo, Y. Pérez, Pérez-Pérez, E. G., Rho, C. D., Rosa-González, D., Ruiz-Velasco, E., Greus, F. Salesa, Sandoval, A., Schneider, M., Schoorlemmer, H., Serna-Franco, J., Smith, A. J., Springer, R. W., Surajbali, P., Tollefson, K., Torres, I., Torres-Escobedo, R., Turner, R., Ureña-Mena, F., Villaseñor, L., Weisgarber, T., Willox, E., and Zhou, H.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The High Altitude Water Cherenkov (HAWC) observatory and the High Energy Stereoscopic System (H.E.S.S.) are two leading instruments in the ground-based very-high-energy gamma-ray domain. HAWC employs the water Cherenkov detection (WCD) technique, while H.E.S.S. is an array of Imaging Atmospheric Cherenkov Telescopes (IACTs). The two facilities therefore differ in multiple aspects, including their observation strategy, the size of their field of view and their angular resolution, leading to different analysis approaches. Until now, it has been unclear if the results of observations by both types of instruments are consistent: several of the recently discovered HAWC sources have been followed up by IACTs, resulting in a confirmed detection only in a minority of cases. With this paper, we go further and try to resolve the tensions between previous results by performing a new analysis of the H.E.S.S. Galactic plane survey data, applying an analysis technique comparable between H.E.S.S. and HAWC. Events above 1 TeV are selected for both datasets, the point spread function of H.E.S.S. is broadened to approach that of HAWC, and a similar background estimation method is used. This is the first detailed comparison of the Galactic plane observed by both instruments. H.E.S.S. can confirm the gamma-ray emission of four HAWC sources among seven previously undetected by IACTs, while the three others have measured fluxes below the sensitivity of the H.E.S.S. dataset. Remaining differences in the overall gamma-ray flux can be explained by the systematic uncertainties. Therefore, we confirm a consistent view of the gamma-ray sky between WCD and IACT techniques.

Published
2021
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40. Evidence of 100 TeV $\gamma$-ray emission from HESS J1702-420: A new PeVatron candidate

Author

Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzynski, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panny, S., Panter, M., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schäfer, J., Schüssler, F., Schutte, H. M., Schwanke, U., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Thiersen, J. H. E., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., Żywucka, N., and Acero, F.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The identification of PeVatrons, hadronic particle accelerators reaching the knee of the cosmic ray spectrum (few $10^{15}$ eV), is crucial to understand the origin of cosmic rays in the Galaxy. We provide an update on the unidentified source HESS J1702-420, a promising PeVatron candidate. We present new observations of HESS J1702-420 made with the High Energy Stereoscopic System (H.E.S.S.), and processed using improved analysis techniques. The analysis configuration was optimized to enhance the collection area at the highest energies. We applied a three-dimensional (3D) likelihood analysis to model the source region and adjust non thermal radiative spectral models to the $\gamma$-ray data. We also analyzed archival data from the Fermi Large Area Telescope (LAT) to constrain the source spectrum at $\gamma$-ray energies >10 GeV. We report the detection of a new source component called HESS J1702-420A, that was separated from the bulk of TeV emission at a $5.4\sigma$ confidence level. The power law $\gamma$-ray spectrum of HESS J1702-420A extends with an index of $\Gamma=1.53\pm0.19_\text{stat}\pm0.20_\text{sys}$ and without curvature up to the energy band 64-113 TeV, in which it was detected by H.E.S.S. at a $4.0\sigma$ confidence level. This brings evidence for the source emission up to $100\,\text{TeV}$, which makes HESS J1702-420A a compelling candidate site for the presence of extremely high energy cosmic rays. Remarkably, in a hadronic scenario, the cut-off energy of the proton distribution powering HESS J1702-420A is found to be higher than 0.5 PeV at a 95% confidence level. HESS J1702-420A becomes therefore one of the most solid PeVatron candidates detected so far in H.E.S.S. data, altough a leptonic origin of its emission could not be ruled out either., Comment: Accepted for publication in the 2. Astrophysical processes section of Astronomy & Astrophysics

Published
2021
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41. Search for dark matter annihilation signals from unidentified Fermi-LAT objects with H.E.S.S

Author

Collaboration, H. E. S. S., Abdallah, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brose, R., Brun, F., Bulik, T., Bylund, T., Cangemi, F., Caroff, S., Casanova, S., Chambery, P., Chand, J. Catalano T., Chen, A., Cotter, G., Curylo, M., Dalgleish, H., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Devin, J., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dreyer, L., Plessis, L. Du, Duffy, C., Egberts, K., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Grondin, M. -H., Hattingh, S., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huang, Z., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Joshi, V., Jung-Richardt, I., Kasai, E., Katarzyński, K., Katz, U., Khangulyan, D., Khèlifi, B., Klepser, S., Kluzniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Mezek, G. Kukec, Kundu, A., Lamanna, G., Stum, S. Le, Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leuschner, F., Levy, C., Lohse, T., Luashvili, A., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martì-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A., Moderski, R., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niemiec, J., Noel, A., Oberholzer, L., O'Brien, P., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Pita, S., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Romoli, C., Rowell, G., Rudak, B., Ricarte, H. Rueda, Ruiz-Velasco, E., Sahakian, V., Sailer, S., Salzmann, H., Sanchez, D. A., Santangelo, A., Sasaki, M., Schüssler, F., Schutte, H. M., Schwanke, U., Senniappan, M., Seyffert, A. S., Shapopi, J. N. S., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spackman, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tanaka, T., Tavernier, T., Taylor, A. M., Terrier, R., Morgan, C. Thorpe, Thiersen, J. H. E., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tsuji, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Völk, H. J., Wagner, S. J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yassin, H., Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S., Zmija, A., Zorn, J., Zouari, S., and Zywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Cosmological $N$-body simulations show that Milky Way-sized galaxies harbor a population of unmerged dark matter subhalos. These subhalos could shine in gamma-rays and be eventually detected in gamma-ray surveys as unidentified sources. We performed a thorough selection among unidentified Fermi-LAT Objects (UFOs) to identify them as possible TeV-scale dark matter subhalo candidates. We search for very-high-energy (E $\gtrsim$ 100 GeV) gamma-ray emissions using H.E.S.S. observations towards four selected UFOs. Since no significant very-high-energy gamma-ray emission is detected in any dataset of the four observed UFOs nor in the combined UFO dataset, strong constraints are derived on the product of the velocity-weighted annihilation cross section $\langle \sigma v \rangle$ by the $J$-factor for the dark matter models. The 95% C.L. observed upper limits derived from combined H.E.S.S. observations reach $\langle \sigma v \rangle J$ values of 3.7$\times$10$^{-5}$ and 8.1$\times$10$^{-6}$ GeV$^2$cm$^{-2}$s$^{-1}$ in the $W^+W^-$ and $\tau^+\tau^-$ channels, respectively, for a 1 TeV dark matter mass. Focusing on thermal WIMPs, the H.E.S.S. constraints restrict the $J$-factors to lie in the range 6.1$\times$10$^{19}$ - 2.0$\times$10$^{21}$ GeV$^2$cm$^{-5}$, and the masses to lie between 0.2 and 6 TeV in the $W^+W^-$ channel. For the $\tau^+\tau^-$ channel, the $J$-factors lie in the range 7.0$\times$10$^{19}$ - 7.1$\times$10$^{20}$ GeV$^2$cm$^{-5}$ and the masses lie between 0.2 and 0.5 TeV. Assuming model-dependent predictions from cosmological N-body simulations on the $J$-factor distribution for Milky Way-sized galaxies, the dark matter models with masses greater than 0.3 TeV for the UFO emissions can be ruled out at high confidence level., Comment: 11 pages, 7 figures, matches accepted version in The Astrophysical Journal

Published
2021
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42. Probing the evolution of the EBL photon density out to $z~\sim 1$ via $\gamma$-ray propagation measurements with Fermi

Author

Singh, K. K., Yadav, K. K., and Meintjes, P. J.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The redshift ($z$) evolution of the Extragalactic Background Light (EBL) photon density is very important to understand the history of cosmological structure formation of galaxies and stars since the epoch of recombination. The EBL photons with the characteristic spectral energy distribution ranging from ultraviolet/optical to far-infrared provide a major source of opacity of the Universe to the GeV-TeV $\gamma$-rays travelling over cosmological distances. The effect of the EBL is very significant through $\gamma \gamma \rightarrow e^- e^+$ absorption process on the propagation of the $\gamma$-ray photons with energy $E >$ 50 GeV emitted from the sources at $z \sim 1$. This effect is characterized by the optical depth ($\tau$) which strongly depends on $E$, $z$ and density of the EBL photons. The proper density of the EBL photons increases with $z$ due to expansion of the Universe whereas evolution of radiation sources contributing to the EBL leads to a decrease in the density with increasing $z$. Therefore, the resultant volumetric evolution of the EBL photon density is approximated by a modified redshift dependence. In this work, we probe evolution of the EBL photon density predicted by two prominent models using cosmic gamma-ray horizon ($\tau (E,z)=$ 1) determined by the measurements from the \emph{Fermi}-Large Area Telescope (LAT) observations. The modified redshift dependence of the EBL photon density is optimized for a given EBL model by estimating the same gamma-ray horizon as predicted by the \emph{Fermi}-LAT observations. We further compare the optical depth estimates in the energy range $E =$ 4 GeV-1 TeV and redshift range $z =0.01-1$ from the \emph{Fermi}-LAT observations with the values derived from the two EBL models to further constrain the evolution of the EBL photon density in the $z~\sim 1$ Universe., Comment: 9 Pages, 6 Figures: Accepted for Publication in Astrophysics and Space Science

Published
2021
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43. Search for dark matter annihilation in the dwarf irregular galaxy WLM with H.E.S.S

Author

Collaboration, H. E. S. S., Abdallah, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Armand, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., de Lavergne, M. de Bony, Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Chand, T., Chandra, S., Chen, A., Cotter, G., Curylo, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Duffy, C., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kasai, E., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khèlifi, B., Klepser, S., Kluzniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marchegiani, P., Marcowith, A., Mares, A., Martì-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, L., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S., Zorn, J., Zouari, S., and Zywucka, N.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract

We search for an indirect signal of dark matter through very high-energy gamma rays from the Wolf-Lundmark-Melotte (WLM) dwarf irregular galaxy. The pair annihilation of dark matter particles would produce Standard Model particles in the final state such as gamma rays, which might be detected by ground-based Cherenkov telescopes. Dwarf irregular galaxies represent promising targets as they are dark matter dominated objects with well measured kinematics and small uncertainties on their dark matter distribution profiles. In 2018, the H.E.S.S. five-telescope array observed the dwarf irregular galaxy WLM for 18 hours. We present the first analysis based on data obtained from an imaging atmospheric Cherenkov telescope for this subclass of dwarf galaxy. As we do not observe any significant excess in the direction of WLM, we interpret the result in terms of constraints on the velocity-weighted cross section for dark matter pair annihilation as a function of the dark matter particle mass for various continuum channels as well as the prompt gamma-gamma emission. For the $\tau^+\tau^-$ channel the limits reach a $\langle \sigma v \rangle$ value of about $4\times 10^{-22}$ cm3s-1 for a dark matter particle mass of 1 TeV. For the prompt gamma-gamma channel, the upper limit reaches a $\langle \sigma v \rangle$ value of about $5 \times10^{-24}$ cm3s-1 for a mass of 370 GeV. These limits represent an improvement of up to a factor 200 with respect to previous results for the dwarf irregular galaxies for TeV dark matter search., Comment: 13 pages, 5 figures

Published
2021
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44. Pulmonary hypertension in adults completing tuberculosis treatment

Author

B W Allwood, S Manie, M Stolbrink, L Hunter, S Mathee, G Meintjes, S L Amosun, A Pecoraro, G Walzl, and E Irusen

Subjects
post-tuberculosis, pulmonary hypertension, echocardiography, tuberculosis, cor pulmonale, Diseases of the respiratory system, RC705-779, Medical emergencies. Critical care. Intensive care. First aid, RC86-88.9
Abstract

Background. Pulmonary hypertension (PH) after tuberculosis (TB) is typically not included among the chronic lung diseases causing PH (group 3 PH), with few data available to support the inclusion. Objectives. To determine the prevalence of PH in an adult population completing TB treatment. Methods. This single-centre, cross-sectional study only included patients with their first documented episode of TB, and who were in the second half of treatment or had recently completed treatment. PH was assessed using transthoracic echocardiography. Questionnaires were also completed and spirometry and a 6-minute walk test were performed. Results. One hundred patients were enrolled, with a mean age of 37.1 years, of whom 58% were male and 46% HIV positive. The median time since initiation of TB treatment was 22 weeks. The mean (standard deviation) measured right ventricular systolic pressure (RVSP) was 23.6 (6.24) mmHg. One participant had PH (defined as RVSP ≥40 mmHg; 95% confidence interval (CI) 0.0 - 3.0) and a further 3 had possible PH (RVSP ≥35 and

Published
2023
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45. A point-prevalence study of body mass indices in HIV-positive and HIV-negative patients admitted to hospital with COVID-19 in South Africa

Author

A Parker, A G B Broadhurst, M S Moolla, L Amien, R Ahmed, J J Taljaard, G Meintjes, P Nyasulu, and C F N Koegelenberg

Subjects
hiv, obesity, multimorbidity, covid-19, Diseases of the respiratory system, RC705-779, Medical emergencies. Critical care. Intensive care. First aid, RC86-88.9
Abstract

Background. Obesity is now well recognised as a risk factor for severe COVID‐19, but the true prevalence of obesity in hospitalised adults with COVID‐19 remains unclear because formal body mass indices (BMIs) are not routinely measured on admission. Objectives. To describe the true prevalence of obesity measured by the BMI, and associated comorbidities, in patients hospitalised with severe COVID‐19, including people with HIV (PWH). Methods. We conducted a point‐prevalence study of measured BMI in consecutive patients with severe COVID‐19 admitted to the medical COVID‐19 wards in a tertiary academic hospital in Cape Town, South Africa (SA). Patients were enrolled over a 2‐week period during the peak of the first COVID‐19 wave in SA. Results. We were able to measure the BMI in 122 of the 146 patients admitted during the study period. The prevalence of HIV was 20% (n=24/122). Most of the participants were overweight or obese (n=104; 85%), and 84 (68.9%) met criteria for obesity. The mean (standard deviation) BMI was 33 (7.5), and 34.5 (9.1) in PWH. Of PWH, 83% (n=20/24) were overweight or obese and 75% (n=18) met criteria for obesity. Multimorbidity was present in 22 (92%) of PWH. Conclusion. We found that most patients, including PWH, met criteria for being overweight or obese. The high prevalence of obesity in PWH and severe COVID‐19 reinforces the need for targeted management of non‐communicable diseases, including obesity, in PWH.

Published
2023
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46. Properties of white dwarf in the binary system AR Scorpii and its observed features

Author

Singh, K. K., Meintjes, P. J., and Yadav, K. K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The binary system AR Scorpii hosts an M-type main sequence cool star orbiting around a magnetic white dwarf in the Milky Way Galaxy. The broadband non-thermal emission over radio, optical and X-ray wavebands observed from AR Scorpii indicates strong modulations on the spin frequency of the white dwarf as well as the spin-orbit beat frequency of the system. Therefore, AR Scorpii is also referred to as a white dwarf pulsar wherein a fast spinning white dwarf star plays very crucial role in the broadband non-thermal emission. Several interpretations for the observed features of AR Scorpii appear in the literature without firm conclusions. In this work, we investigate connection between some of the important physical properties like spin-down power, surface magnetic field, equation of state, temperature and gravity associated with the white dwarf in the binary system AR Scorpii and its observational characteristics. We explore the plausible effects of white dwarf surface magentic field on the absence of substantial accretion in this binary system and also discuss the gravitational wave emission due to magnetic deformation mechanism., Comment: 8 Pages, 1 Figure, Accepted for Publication in Modern Physics Letters A (MPLA)

Published
2021
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47. Progenitor, environment, and modelling of the interacting transient, AT 2016jbu (Gaia16cfr)

Author

Brennan, S. J., Fraser, M., Johansson, J., Pastorello, A., Kotak, R., Stevance, H. F., Chen, T. -W., Eldridge, J. J., Bose, S., Brown, P. J., Callis, E., Cartier, R., Dennefeld, M., Dong, Subo, Duffy, P., Elias-Rosa, N., Hosseinzadeh, G., Hsiao, E., Kuncarayakti, H., Martin-Carrillo, A., Monard, B., Pignata, G., Sand, D., Shappee, B. J., Smartt, S. J., Tucker, B. E., Wyrzykowski, L., Abbot, H., Benetti, S., Blondin, S., Chen, Ping, Bento, J., Delgado, A., Galbany, L., Gromadzki, M., Gutiérrez, C. P., Hanlon, L., Harrison, D. L., Hiramatsu, D., Hodgkin, S. T., Holoien, T. W. -S., Howell, D. A., Inserra, C., Kankare, E., Kozlowski, S., Maguire, K., Müller-Bravo, T. E., McCully, C., Meintjes, P., Morrell, N., Nicholl, M., O'Neill, D., Pietrukowicz, P., Poleski, R., Prieto, J. L., Rau, A., Reichart, D. E., Schweyer, T., Shahbandeh, M., Skowron, J., Sollerman, J., Soszńyski, I., Stritzinger, M. D., Szymański, M., Tartaglia, L., Udalski, A., Ulaczyk, K., Young, D. R., van Leeuwen, M., and van Soelen, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the bolometric lightcurve, identification and analysis of the progenitor candidate, and preliminary modelling of AT2016jbu (Gaia16cfr). We find a progenitor consistent with a $\sim$22--25~$M_{\odot}$ yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong H$\alpha$ emission consistent with pre-existing circumstellar material. The age of the environment as well as the resolved stellar population surrounding AT2016jbu, support a progenitor age of $>$10 Myr, consistent with a progenitor mass of $\sim$22~$M_{\odot}$. A joint analysis of the velocity evolution of AT2016jbu, and the photospheric radius inferred from the bolometric lightcurve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity $\sim$650$kms^{-1}$, while the second, more energetic event, ejected material at $\sim$4500$kms^{-1}$. Whether the latter is the core-collapse of the progenitor remains uncertain. We place a limit on the ejected $^{56}$Ni mass of $<$0.016$M_{\odot}$. Using the BPASS code, we explore a wide range of possible progenitor systems, and find that the majority of these are in binaries, some of which are undergoing mass transfer or common envelope evolution immediately prior to explosion. Finally, we use the SNEC code to demonstrate that the low-energy explosion within some of these binary systems, together with sufficient CSM, can reproduce the overall morphology of the lightcurve of AT2016jbu., Comment: 23 pages, 15 figures, accepted for publication in MNRAS

Published
2021
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48. Photometric and spectroscopic evolution of the interacting transient AT 2016jbu (Gaia16cfr)

Author

Brennan, S. J., Fraser, M., Johansson, J., Pastorello, A., Kotak, R., Stevance, H. F., Chen, T. -W., Eldridge, J. J., Bose, S., Brown, P. J., Callis, E., Cartier, R., Dennefeld, M., Dong, Subo, Duffy, P., Elias-Rosa, N., Hosseinzadeh, G., Hsiao, E., Kuncarayakti, H., Martin-Carrillo, A., Monard, B., Nyholm, A., Pignata, G., Sand, D., Shappee, B. J., Smartt, S. J., Tucker, B. E., Wyrzykowski, L., Abbot, H., Benetti, S., Blondin, S., Chen, Ping, Bento, J., Delgado, A., Galbany, L., Gromadzki, M., Gutiérrez, C. P., Hanlon, L., Harrison, D. L., Hiramatsu, D., Hodgkin, S. T., Holoien, T. W. -S., Howell, D. A., Inserra, C., Kankare, E., Kozlowski, S., Maguire, K., Müller-Bravo, T. E., McCully, C., Meintjes, P., Morrell, N., Nicholl, M., O'Neill, D., Pietrukowicz, P., Poleski, R., Prieto, J. L., Rau, A., Reichart, D. E., Schweyer, T., Shahbandeh, M., Skowron, J., Sollerman, J., Soszńyski, I., Stritzinger, M. D., Szymański, M., Tartaglia, L., Udalski, A., Ulaczyk, K., Young, D. R., van Leeuwen, M., and van Soelen, B.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results from a high cadence, multi-wavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This dataset complements the current literature by adding higher cadence as well as extended coverage of the lightcurve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of M$_V\sim$-18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500km$s^{-1}$ seen in narrow emission features from a slow moving CSM, and up to 10,000km$s^{-1}$ seen in broad absorption from some high velocity material. Late-time spectra ($\sim$+1 year) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He i and Ca ii. Strong asymmetric emission features, a bumpy lightcurve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H$\alpha$ among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients., Comment: 27 pages, 21 figures, accepted for publication in MNRAS

Published
2021
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49. Global guideline for the diagnosis and management of the endemic mycoses: an initiative of the European Confederation of Medical Mycology in cooperation with the International Society for Human and Animal Mycology

Author

Thompson, George R, Le, Thuy, Chindamporn, Ariya, Kauffman, Carol A, Alastruey-Izquierdo, Ana, Ampel, Neil M, Andes, David R, Armstrong-James, Darius, Ayanlowo, Olusola, Baddley, John W, Barker, Bridget M, Lopes Bezerra, Leila, Buitrago, Maria J, Chamani-Tabriz, Leili, Chan, Jasper FW, Chayakulkeeree, Methee, Cornely, Oliver A, Cunwei, Cao, Gangneux, Jean-Pierre, Govender, Nelesh P, Hagen, Ferry, Hedayati, Mohammad T, Hohl, Tobias M, Jouvion, Grégory, Kenyon, Chris, Kibbler, Christopher C, Klimko, Nikolai, Kong, David CM, Krause, Robert, Lee Lee, Low, Meintjes, Graeme, Miceli, Marisa H, Rath, Peter-Michael, Spec, Andrej, Queiroz-Telles, Flavio, Variava, Ebrahim, Verweij, Paul E, Schwartz, Ilan S, and Pasqualotto, Alessandro C

Subjects
Infectious Diseases, Prevention, Emerging Infectious Diseases, Vaccine Related, Biodefense, Infection, Good Health and Well Being, Animals, Clinical Decision-Making, Consensus, Endemic Diseases, Europe, Global Health, Guidelines as Topic, Humans, International Cooperation, Mycoses, Risk Factors, Clinical Sciences, Medical Microbiology, Public Health and Health Services, Microbiology
Abstract

The global burden of the endemic mycoses (blastomycosis, coccidioidomycosis, emergomycosis, histoplasmosis, paracoccidioidomycosis, sporotrichosis, and talaromycosis) continues to rise yearly and these infectious diseases remain a leading cause of patient morbidity and mortality worldwide. Management of the associated pathogens requires a thorough understanding of the epidemiology, risk factors, diagnostic methods and performance characteristics in different patient populations, and treatment options unique to each infection. Guidance on the management of these infections has the potential to improve prognosis. The recommendations outlined in this Review are part of the "One World, One Guideline" initiative of the European Confederation of Medical Mycology. Experts from 23 countries contributed to the development of these guidelines. The aim of this Review is to provide an up-to-date consensus and practical guidance in clinical decision making, by engaging physicians and scientists involved in various aspects of clinical management.

Published
2021

50. Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016

Author

Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arcaro, C., Arm, C., Armstrong, T., Ashkar, H., Backes, M., Baghmanyan, V., Martins, V. Barbosa, Barnacka, A., Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Bi, B., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., de Lavergne, M. de Bony, Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Caroff, S., Carosi, A., Casanova, S., Ch, T., Ch, S., Chen, A., Cotter, G., Curyło, M., Mbarubucyeye, J. Damascene, Davids, I. D., Davies, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Dyks, J., Egberts, K., Eichhorn, F., Einecke, S., Emery, G., Ernenwein, J. -P., Feijen, K., Fegan, S., Fiasson, A., de Clairfontaine, G. Fichet, Filipovic, M., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Giavitto, G., Giunti, L., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Hörbe, M., Horns, D., Huber, D., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Joshi, V., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katz, U., Khangulyan, D., Khélifi, B., Klepser, S., Kluźniak, W., Komin, Nu., Konno, R., Kosack, K., Kostunin, D., Kreter, M., Lamanna, G., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Mar, V., Marchegiani, P., Marcowith, A., Mares, A., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Montanari, A., Moore, C., Morris, P., Moulin, E., Muller, J., Murach, T., Nakashima, K., Nayerhoda, A., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Olivera-Nieto, L., Wilhelmi, E. de Ona, Ostrowski, M., Panter, M., Panny, S., Parsons, R. D., Peron, G., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reichherzer, P., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Sailer, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Scalici, M., Schüssler, F., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spencer, S., Spir-Jacob, M., Stawarz, Ł., Sun, L., Steenkamp, R., Stegmann, C., Steinmassl, S., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Tomankova, L., Trichard, C., Tsirou, M., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Watson, J., Werner, F., White, R., Wierzcholska, A., Wong, Yu Wun, Yusafzai, A., Zacharias, M., Zanin, R., Zargaryan, D., Zdziarski, A. A., Zech, A., Zhu, S. J., Zorn, J., Zouari, S., Żywucka, N., Collaboration, MAGIC, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Bil, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Depaoli, D., Di Pierro, F., Di Venere, L., neira, E. Do Souto Espi\, Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Ferrara, G., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinović, N., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Loporchio, S., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Mender, S., Mićanović, S., Miceli, D., Miener, T., Minev, M., Mir, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletić, L., nil, P. Pe\, Perennes, C., Persic, M., Moroni, P. G. Prada, Pr, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tosti, L., Truzzi, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zarić, D., Jorstad, S. G., Marscher, A. P., Boccardi, B., Casadio, C., Hodgson, J., Kim, J. -Y., Krichbaum, T. P., Lähteenmäki, A., Tornikoski, M., Traianou, E., and Weaver, Z. R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, $E>100\,$GeV) $\gamma$-rays. VHE $\gamma$-ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE $\gamma$-ray intranight variability in this source. While a common variability timescale of $1.5\,$hr is found, there is a significant deviation near the end of the flare with a timescale of $\sim 20\,$min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE $\gamma$-ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the $\gamma$-ray flare, even though the detailed flux evolution differs from the VHE ightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, $E>100\,$MeV) $\gamma$-ray band only a moderate flux increase is observed with Fermi-LAT, while the HE $\gamma$-ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the $\gamma$-ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located $\sim 50\,$pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE $\gamma$ rays have been produced far down the jet where turbulent plasma crosses a standing shock., Comment: 25 pages, 17 figures. Accepted for publication by Astronomy & Astrophysics. Corresponding authors: M. Zacharias, J. Sitarek, D. Sanchez, T. Terzic

Published
2020
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