The X-ray outburst of the Galactic Centre magnetar SGR J1745−2900 during the first 1.5 year

In 2013 April a new magnetar, SGR 1745−2900, was discovered as it entered an outburst, at only 2.4 arcsec angular distance from the supermassive black hole at the centre of the Milky Way, Sagittarius A*. SGR 1745−2900 has a surface dipolar magnetic field of ∼2 × 1014 G, and it is the neutron star closest to a black hole ever observed. The new source was detected both in the radio and X-ray bands, with a peak X-ray luminosity LX ∼ 5 × 1035 erg s−1. Here we report on the long-term Chandra (25 observations) and XMM–Newton (eight observations) X-ray monitoring campaign of SGR 1745−2900 from the onset of the outburst in 2013 April until 2014 September. This unprecedented data set allows us to refine the timing properties of the source, as well as to study the outburst spectral evolution as a function of time and rotational phase. Our timing analysis confirms the increase in the spin period derivative by a factor of ∼2 around 2013 June, and reveals that a further increase occurred between 2013 October 30 and 2014 February 21. We find that the period derivative changed from 6.6 × 10−12 to 3.3 × 10−11 s s−1 in 1.5 yr. On the other hand, this magnetar shows a slow flux decay compared to other magnetars and a rather inefficient surface cooling. In particular, starquake-induced crustal cooling models alone have difficulty in explaining the high luminosity of the source for the first ∼200 d of its outburst, and additional heating of the star surface from currents flowing in a twisted magnetic bundle is probably playing an important role in the outburst evolution.

París, destino privilegiado del exilio español (1813-1851): a propósito de varias aportaciones historiográficas recientes

París es una ciudad mítica que siempre ha despertado un especial poder de atracción entre las élites políticas y culturales. Solo un reducido número de afrancesados y liberales españoles que en el siglo XIX se vieron forzados al exilio, tuvieron la posibilidad legal de buscar refugio político –en ocasiones una nueva patria– en la capital francesa. En la última década, se ha producido un extraordinario avance historiográfico en el conocimiento de las características y particularidades del exilio español en París, gracias a la publicación de varias monografías, artículos y biografías sobre el tema. Este artículo pretende dar a conocer una selección de estos trabajos y conectar algunas de sus principales aportaciones.

A highly resistive layer within the crust of X-ray pulsars limits their spin periods

The lack of isolated X-ray pulsars with spin periods longer than 12 s raises the question of where the population of evolved high-magnetic-field neutron stars has gone. Unlike canonical radiopulsars, X-ray pulsars are not subject to physical limits to the emission mechanism nor observational biases against the detection of sources with longer periods. Here we show that a highly resistive layer in the innermost part of the crust of neutron stars naturally limits the spin period to a maximum value of about 10–20 s. This highly resistive layer is expected if the inner crust is amorphous and heterogeneous in nuclear charge, possibly owing to the existence of a nuclear ‘pasta’ phase. Our findings suggest that the maximum period of isolated X-ray pulsars may be the first observational evidence for an amorphous inner crust, whose properties can be further constrained by future X-ray timing missions combined with more detailed models.

The European Resonance of Napoleon’s Defeat in Spain

The military event that sealed the defeat of Napoleon in Spain was the Battle of Vitoria on 21st June 1813, which saw the allied British, Spanish and Portuguese troops led by Wellington gain victory over Joseph Bonaparte's forces. It was the last great battle of what is known in Spain as the Guerra de la Independencia, in the United Kingdom as the Peninsular War and in France as the Guerre d'Espagne. While a sliver of Spanish territory remained under French control and the war itself went on for a few more months, it was the Battle of Vitoria that marked the end of Napoleon's rule on the Iberian Peninsula, as symbolised by the departure from Spain of Joseph Bonaparte, the monarch who had been imposed five years earlier to remove the Bourbons from the Spanish throne.

Sites of Chemistry in the Nineteenth Century

The three articles in this special issue of Ambix were among the twenty-one papers presented at the conference “Sites of Chemistry in the Nineteenth Century,” held in Valencia at the Institute for the History of Medicine and Science ‘López Piñero’ in July 2012. This meeting was the second of the series of conferences organised as part of the project Sites of Chemistry, 1600–2000, the aim of which was to investigate the wide and diverse range of physical spaces and places where chemistry has been practised from the early modern period to the twentieth century.