Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions

High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies. In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system. We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields. We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations.The INTEGRALteams in the participating countries acknowledge the continuous support from their space agencies and funding organizations: the Italian Space Agency ASI (via different agreements including the latest one, 2019-35HH, and the ASIINAF agreement 2017-14-H.0), the French Centre national d’études spatiales (CNES), the Russian Foundation for Basic Research (KP, 19-02-00790), the Russian Science Foundation (ST, VD, AL; 19-12-00423), the Spanish State Research Agency (via different grants including ESP2017-85691-P, ESP2017-87676-C5-1-R and Unidad de Excelencia María de Maeztu – CAB MDM-2017-0737). IN is partially supported by the Spanish Government under grant PGC2018-093741-B-C21/C22 (MICIU/AEI/FEDER, UE). LD acknowledges grant 50 OG 1902

Detrimental Effects of Debris Dents on Rolling Contact Fatigue

Debris dents produced by solid particles in suspension in oil or grease when they travel through an EHL contact may be at the origin of rolling bearing failures. A summary of an experimental investigation carried out to identify (i) the particle entry ratio, (ii) the mechanisms of particle fragmentation or deformation, (iii) the resulting indentation features, and (iv) the initiation site of subsequent surface damage is presented first. Afterwards, numerical simulations of a dent moving through an EHL contact are performed. A critical slide-to-roll ratio is found. Results of our numerical simulations are analyzed and discussed in relation to the concept of infinite life for rolling bearing applications

De l'image brute à l'intensité absolue : calibration d'une caméra Guinier-Méring à collimation linéaire

Nous présentons la calibration d'une caméra de type Guinier-Méring couplée à une anode au molybdène (λ=0.711 Å) et à un monochromateur de quartz. Trois jeux de fentes réduisent le faisceau à 2 mm de largeur sur 15 mm de hauteur dans le plan de l'échantillon. Une chambre à vide primaire est placée entre l'échantillon et le détecteur pour réduire l'absorption des photons diffusés par l'air. La détection se fait par des plaques photosensibles et nous utilisons le numériseur "PhosphorImager" (Molecular DynamicsTM). Pour obtenir un diagramme de diffusion où l'intensite absolue en cm-1 est tracée en fonction du vecteur d'onde q en Å-1, trois problèmes doivent être resolus : la calibration de l'axe des vecteurs d'onde ; la soustraction de la cellule vide et la calibration de l'intensite en cm-1 ; la déconvolution pour se ramener au diagramme idéal qui serait obtenu avec un faisceau ponctuel dans le plan du détecteur. La procédure peut être utilisée pour toute caméra de diffusion aux petits angles associée à des plaques photostimulables.We present here the calibration of a Guinier-Méring small angle X-ray camera. A molybdenum anode source, followed by a quartz monochromator, allows a monochromatic beam with high energy (E=17 keV, (λ=0.711 Å) to be obtained. Three set of slits limit the beam size to 2 mm width and 15 mm high at the sample position. Air scattering is reduced with a primary vacuum chamber set between the sample and the detector. An image plate is used as 2D detector. The final spectrum (absolute intensity in cm-1 plotted versus the q-vector in Å-1) requires three steps in data treatment : the calibration of the q axis, the subtraction of the empty cell and calibration of the intensity and the desmearing to make the scattering pattern what it is supposed to be with a punctual source. The method described here may be applied for any small angle X-ray camera using sensitive flat image plates

Transcriptomic basis of sex loss in the pea aphid

Abstract Background Transitions from sexual to asexual reproduction are common in eukaryotes, but the underlying mechanisms remain poorly known. The pea aphid—Acyrthosiphon pisum—exhibits reproductive polymorphism, with cyclical parthenogenetic and obligate parthenogenetic lineages, offering an opportunity to decipher the genetic basis of sex loss. Previous work on this species identified a single 840 kb region controlling reproductive polymorphism and carrying 32 genes. With the aim of identifying the gene(s) responsible for sex loss and the resulting consequences on the genetic programs controlling sexual or asexual embryogenesis, we compared the transcriptomic response to photoperiod shortening—the main sex-inducing cue—of a sexual and an obligate asexual lineage of the pea aphid, focusing on heads (where the photoperiodic cue is detected) and embryos (the final target of the cue). Results Our analyses revealed that four genes (one expressed in the head, and three in the embryos) of the region responded differently to photoperiod in the two lineages. We also found that the downstream genetic programs expressed during embryonic development of a future sexual female encompass ∼1600 genes, among which miRNAs, piRNAs and histone modification pathways are overrepresented. These genes mainly co-localize in two genomic regions enriched in transposable elements (TEs). Conclusions Our results suggest that the causal polymorphism(s) in the 840 kb region somehow impair downstream epigenetic and post-transcriptional regulations in obligate asexual lineages, thereby sustaining asexual reproduction