Probing large-scale wind structures in Vela X–1 using off-states with INTEGRAL

Vela X–1 is the prototype of the class of wind-fed accreting pulsars in high-mass X-ray binaries hosting a supergiant donor. We have analysed in a systematic way 10 years of INTEGRAL data of Vela X–1 (22–50 keV) and we found that when outside the X-ray eclipse, the source undergoes several luminosity drops where the hard X-rays luminosity goes below ∼3 × 1035 erg s−1, becoming undetected by INTEGRAL. These drops in the X-ray flux are usually referred to as ‘off-states’ in the literature. We have investigated the distribution of these off-states along the Vela X–1 ∼ 8.9 d orbit, finding that their orbital occurrence displays an asymmetric distribution, with a higher probability to observe an off-state near the pre-eclipse than during the post-eclipse. This asymmetry can be explained by scattering of hard X-rays in a region of ionized wind, able to reduce the source hard X-ray brightness preferentially near eclipse ingress. We associate this ionized large-scale wind structure with the photoionization wake produced by the interaction of the supergiant wind with the X-ray emission from the neutron star. We emphasize that this observational result could be obtained thanks to the accumulation of a decade of INTEGRAL data, with observations covering the whole orbit several times, allowing us to detect an asymmetric pattern in the orbital distribution of off-states in Vela X–1.

Relaciones entre conducta agresiva y metas académicas: estudio con una muestra de estudiantes españoles de Educación Secundaria Obligatoria

Este estudio analizó la relación entre la conducta agresiva y las metas académicas en una muestra de 2.022 estudiantes españoles de Educación Secundaria Obligatoria (ESO ). La conducta agresiva fue evaluada con el Teenage Inventory of Social Skills (TISS) y las metas académicas mediante el Achievement Goal Tendencies Questionnaire (AGTQ). Los resultados revelaron que los estudiantes con alta conducta agresiva, de ambos sexos y de todos los cursos académicos de ESO , presentaron puntuaciones significativamente más altas en metas de reforzamiento social que sus iguales con baja conducta agresiva. Los análisis de regresión logística mostraron que la conducta agresiva fue un predictor positivo y estadísticamente significativo de las metas de reforzamiento social en ambos sexos y en todos los cursos de ESO.