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Mathematics and Astronomy in the Ancient World: An East-Asian Perspective
No full textInternational audienceThis book contains an edited selection of the papers presented at the Second International Conference on the History of Ancient Mathematics and Astronomy (ICHAMA), organized by Tang Quan and Qu Anjing and held in Xi’an, 2–8 December 2018, commemorating the foundation. This collection, consisting of papers that have been refined and edited into scientific articles, provides an overview of how the history of science can be international, stepping beyond area studies, without being Euro-centric. Containing chapters written by East Asia scholars who do not publish widely in English, the volume opens an important window into their projects and the state of scholarship in their respective countries in relation to the history of mathematics and astronomy. As the contributions span a spectrum of senior and junior scholars, they are of great interest to an academic audience of researchers and post-graduate students in the history of science and the history of mathematics and astronomy in particular
NGC 3259: A signal for an untapped population of slowly accreting intermediate-mass black holes
No full textInternational audienceLow-mass active galactic nuclei (AGNs) can provide important constraints on the formation and evolution of supermassive black holes (SMBHs), which stands as a central challenge in modern cosmology. To date, only small samples of intermediate-mass black holes (IMBHs, MBH < 10 M⊙) and “lesser” SMBHs (LSMBHs, MBH < 10 M⊙) have been identified. Our present study of NGC 3259 at D = 27 Mpc with the Binospec integral field unit (IFU) spectrograph complemented with Keck Echelle Spectrograph and Imager observations demonstrates the strong capability and necessity for spectroscopic follow-up studies. NGC 3259 hosts a black hole (BH) with a mass of MBH = (2.0 − 4.9)×10 M⊙, inferred from multi-epoch spectroscopic data, which is accreting at 1% of the Eddington limit, as suggested by the analysis of archival XMM-Newton observations. It is the second-nearest broad-line low-mass AGN after the archetypal galaxy NGC 4395. The spectroscopic data reveal a variable broad Hα profile likely resulting from asymmetrically distributed broad-line region (BLR) clouds or BLR outflow events. X-ray observations and the absence of an optical power-law continuum suggest partial obscuration of the accretion disk and hot corona by a dust torus. We estimated that Sloan Digital Sky Survey (SDSS) observations would only have the capacity to detect similar objects up to D = 35 Mpc. A detailed photometric analysis of NGC 3259 using HST images provides a central spheroid stellar mass estimate that is 20 times lower than expected, based on the MBH − Msph* relation, making this galaxy a significant outlier. This discrepancy suggests divergent growth pathways for the central BH and spheroid, potentially influenced by the potential presence of a bar in the galaxy. Finally, we demonstrate that the DESI and 4MOST surveys will detect low-accretion-rate IMBHs and LSMBHs, while the sensitivity of future X-ray instruments (such as AXIS and Athena) will secure their classification
Towards a Coq-verified Chain of Esterel Semantics
No full textInternational audienceThis article focuses on formally specifying and verifying the chain of formal semantics of the Esterel synchronous programming language using the Coq proof assistant. In particular, in addition to the standard logical (LBS) semantics, constructive semantics (CBS) and constructive state semantics (CSS), we introduce a novel microstep semantics that gets rid of the Must/Can potential function pair of the constructive semantics and can be viewed as an abstract version of Esterel’s circuit semantics used by compilers to generate software code and hardware designs. The article also comes with formal proofs in Coq of the equivalence between the CBS and CSS semantics and of the refinement of the CSS by the microstep semantics, except for the loop construct of Esterel
Гривны с драконами: о престижном женском костюме постгуннского времени в степи.
No full textInternational audienceВ статье предпринята попытка выявления восточныхэлементов в престижном женском костюме степного населения пост-гуннского времени (середина V – середина VI в.). К их числу, вероят-нее всего, относится случайная находка фрагментов гривны с оконча-ниями, украшенными изображением головы дракона, обнаруженныху с. Татарка (балка Каряжка), около Ставрополя. Гривна имеет анало-гии в женском уборе V в. из курганного погребения Кара-Агач, в Цен-тральном Казахстане. Кроме того, полихромный декор на изделии изТатарки также имеет восточные параллели и редко представлен навещах эпохи Великого переселения народов к западу от Днепра. Да-тировка находки из Татарки постуннским временем основывается нахронологии так называемых средиземноморских пряжек, одна из ко-торых обнаружена также в Татарке
AIKON : A Modular Computer Vision Platform for Historical Corpora
No full textWe present AIKON, a modular platform designed to foster historians’ collaborations on custom document corpora, and support their workflow by leveraging computer vision processes. Among the many tools that have emerged in recent years to empower historians with AI tools, AIKON stands out by: (i) providing a comprehensive environment, supporting the historians’ workflow from corpus construction to results validation and visualization; (ii) following a modular and scalable design, that makes it easy to customize the platform and to develop new modules
Millimeter emission from supermassive black hole coronae
No full textInternational audienceActive Galactic Nuclei (AGN) host accreting supermassive black holes (SMBHs). The accretion can lead to the formation of a hot, X-ray emitting corona close to the SMBH capable of accelerating relativistic electrons. Observations in the millimetre (mm) band can probe its synchrotron emission. We provide a framework to derive physical information of SMBH coronae by modelling their spectral energy distribution (SED) from radio to far infrared frequencies. We also explore the possibilities of deriving additional information from mm observations, such as the SMBH mass, and studying high-redshift lensed sources. We introduce a corona emission model based on a one-zone spherical region with a hybrid thermal and non-thermal plasma. We investigate in detail how the corona SED depends on different parameters such as size, opacity, and magnetic field strength. Other galactic emission components from dust, ionised gas and diffuse relativistic electrons are also included in the SED fitting scheme. We apply our code consistently to a sample of radio-quiet AGN with strong indications of a coronal component in the mm. The detected mm emission from SMBH coronae is consistent with having a non-thermal relativistic particle population with an energy density that is ~0.5-10% of that in the thermal plasma. This requires magnetic energy densities close to equipartition with the thermal gas, and corona sizes of 60-250 gravitational radii. The model can also reproduce the observed correlation between mm emission and SMBH mass when accounting for uncertainties in the corona size. The mm band offers a unique window into the physics of SMBH coronae, enabling the study of highly dust-obscured sources and high-redshift lensed quasars. Gaining a deeper understanding of the relativistic particle population in SMBH coronae can provide key insights into their potential multiwavelength and neutrino emission
Fermi Unassociated Sources in the MeerKAT Absorption Line Survey
No full textInternational audienceOver 2000 Gamma ray sources identified by the Large Area Telescope (LAT) on NASA's Fermi Gamma-ray Space Telescope are considered unassociated, meaning that they have no known counterparts in any other frequency regime. We have carried out an image-based search for steep spectrum radio sources, with in-band spectral index less than -1.4, within the error regions of Fermi unassociated sources using 1 to 1.4 GHz radio data from the MeerKAT Absorption Line Survey (MALS) Data Release. MALS DR1 with a median rms noise of 22 to 25 microJy and 735,649 sources is a significant advance over past image-based searches with improvements in sensitivity, resolution and bandwidth. Steep spectrum candidates were identified using a combination of in-band spectral indices from MALS and existing radio surveys. We developed an optical and infrared source classification scheme in order to distinguish between galactic pulsars and radio galaxies. In total, we identify nine pulsar candidates towards six Fermi sources that are worthy of follow-up for pulsation searches. We also report 41 steep spectrum radio galaxy candidates that may be of interest in searches for high-redshift radio galaxies. We show that MALS due to its excellent continuum sensitivity can detect 80 percent of the known pulsar population. This exhibits the promise of identifying exotic pulsar candidates with future image-based surveys with the Square Kilometre and its precursors
Finbarr Barry Flood, Beate Frick Tales Things Tell: Material Histories of Early Globalisms Princeton - Oxford, Princeton University Press 2024, 304 p., 190 fig. coul., 22 fig. n&b, 6 cartes ISBN : 9780691215150
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Diamètres et dignités : remarques sur le rapport entre les dimensions des sceaux ecclésiastiques byzantins et l’importance hiérarchique de leurs propriétaires
No full textWas the diameter of a Byzantine seal proportional to the hierarchical importance of its owner? The article proposes an answer to this long-standing question through the quantitative analysis of 2,300 ecclesiastical seals. Within the Church, the dimensions of the blanks do not appear to be directly and unambiguously related to the personal hierarchical status of the sealer. Nevertheless, several factors coexist in the practice of sealing: on the one hand, modularity; on the other, in certain cases, a pursuit of personal expression.Est-ce que dans le monde byzantin le diamètre des sceaux en plomb était directement proportionnel à l’importance hiérarchique de son propriétaire ? Cet article propose une réponse à cette question désormais séculaire à travers l’analyse quantitative de 2300 sceaux ecclésiastiques. Au sein de l’Eglise, les dimensions des flans ne semblent pas liées directement et de manière évidente au statut hiérarchique personnel du sigillant. Néanmoins, plusieurs instances coexistent dans les pratiques de scellement : d’un côté modularité, et de l’autre, chez certains, la recherche d’une touche personnelle.Le document présente dans le détail la méthodologie et le corpus de données utilisés dans le cadre de l’étude "Diamètres et dignités : remarques sur le rapport entre les dimensions des sceaux ecclésiastiques byzantins et l’importance hiérarchique de leurs propriétaires", publié dans le volume no. 182, 2025 de la Revue Numismatique, qui contient aussi les références bibliographiques cités en bas de page