On the nature of some SGRs and AXPs as rotation-powered neutron stars

We investigate the possibility that some SGRs/AXPs could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, $L_X/\dot{E}_{\rm rot}$, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for $L_X$ computed in the soft (2--10~keV) X-ray band. We compute the range of NS masses for which $L_X/\dot{E}_{\rm rot}<1$. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to $L_X/\dot{E}_{\rm rot}>1$ in two of them. We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2--10~keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with $L_X/\dot{E}_{\rm rot}<1$ becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.Comment: 11 pages, 14 figures, to appear in A&

Una aproximación sintaxonómica sobre la vegetación del Perú. Clases, órdenes y alianzas

RESUMEN. Una aproximación sintaxonómica sobre la vegetación del Perú. Clases, órdenes y alianzas. En el presente trabajo damos a conocer una primera aproximación al esquema sintaxonómico de la vegetación peruana hasta el nivel de alianza. Se describen dos nuevas clases (Nicotiano- Ambrosietea y Mayaceteaf luviatilis), 12 órdenes (Adiantetalia raddiani, Alnetalia, Cestro-Prunetalia, Commelinetalia, Cryptocarpo-Prosopidetalia, Mutisio-Baccharidetalia, Nicotianetalia, Oryzo- Hymenachnetalia, Polylepidetalia racemosae, Polypodio-Puyetalia, Salicetalia caroliniano- humbolchianae ySaxifragetalia magellanicae), 14 alianzas (Adiantion subvolubilis, Aristido-Chloridion, Bursero-Prosopidion, Espostoo-Neoraimondion, Loasion, Mutisio-Ophryosporidion, Myrcianthion quinquelobae, Myrico-Alnion, Peperomio-Puyion, Ribesido-Polylepidion, Saxifragion magellanicae, Sicyo-Urficion„Siegesbeckio-Commelinion y Tecomion arequipensis) y 10 asociaciones (Adiantetum subvolubilis, Bartiadesio-Ophryosporidetum, Cercidio-Prosopidetum, Haageocereo-Neoraimondietum, Peperomio-Tillculdsietum, Philoglosso-Uroccopidetum,Schino-Acacietum,Tristerido-Myrcianthetum, Valeriano-Saxifragetum y Valleo-Alnetutn). Además se establece un estado nuevo (Chusqueetalia tessellatae stat.nov.)que permite sistematizar los matorrales andinos con bambusoideas ("chuscales").Palabras clave. Vegetación, Fitosociología, Sintaxonomfa, Perú.ABSTRACT. A syntaxonomic approximation about the vegetation of Peru. Classes, orders and alliances. In this paper, a first syntaxonomic approximation to the syntaxonomic scheme of the Peruvian vegetation down to the alliance level is presented. Two new classes (Nicoticmo-Ambrosietea and Mayacetea f hiviatilis), 12 orders (Adiantetalia raddiani, Alnetalia, Cestro-Prunetalia, Commelinetalia, Cryptocarpo-Prosopidetalia, Mutisio-Baccharidetalia, Nicotianetalia, Oryzo- Hymenachnetalia, Polylepidetalia racemosae, Polypodio-Puyetalia, Salicetalia caroliniano- humboldnanae and Saxifragetalia magellanicae), 14 alliances (Adicional subvolubilis, Aristido- Chloridion, Bursero-Prosopidion, Espostoo-Neoraimondion, Loasion, Munsio-Ophryosporidion, Myrciamhion quinquelobae, Myrico-Alnion, Peperomio-Puyion, Ribesido-Polylepidion, Saxifragion magellanicae, Sicyo-Urticion„Siegesbeckio-Commelinion and Tecomion arequipensis) and 10 associations (Adiametum subvolubilis, Bartiadesio-Ophryosporidetum, Cercidio-Prosopidetum, Haageocereo-Neoraimondietum, Peperomio-Tillandsiencm, Philoglosso-Urocarpidetutn, Schino- Acacietum, Tristerido-Myrcianthetum, Valeriano-Saxifragetunt and Valleo-Alnetum) are described. Also, a new status is stablished (Chusqueetalia tessellatae stat. nov. ) to systematize the Andean bamboo-scrubs ("chuscales").Key words. Vegetation, Phytosociology, Syntaxonomy, Peru

Smooth kinematic and metallicity gradients between the Milky Way's nuclear star cluster and nuclear stellar disc. Different components of the same structure?

The innermost regions of most galaxies are characterised by the presence of extremely dense nuclear star clusters. Nevertheless, these clusters are not the only stellar component present in galactic nuclei, where larger stellar structures known as nuclear stellar discs, have also been found. Understanding the relation between nuclear star clusters and nuclear stellar discs is challenging due to the large distance towards other galaxies which limits their analysis to integrated light. The Milky Way's centre, at only 8 kpc, hosts a nuclear star cluster and a nuclear stellar disc, constituting a unique template to understand their relation and formation scenario. We aim to study the kinematics and stellar metallicity of stars from the Milky Way's nuclear star cluster and disc to shed light on the relation between these two Galactic centre components. We used publicly available photometric, proper motions, and spectroscopic catalogues to analyse a region of $\sim2.8'\times4.9'$ centred on the Milky Way's nuclear star cluster. We built colour magnitude diagrams, and applied colour cuts to analyse the kinematic and metallicity distributions of Milky Way's nuclear star cluster and disc stars with different extinction along the line of sight. We detect kinematics and metallicity gradients for the analysed stars along the line of sight towards the Milky Way's nuclear star cluster, suggesting a smooth transition between the nuclear stellar disc and cluster. We also find a bi-modal metallicity distribution for all the analysed colour bins, which is compatible with previous work on the bulk population of the nuclear stellar disc and cluster. Our results suggest that these two Galactic centre components might be part of the same structure with the Milky Way's nuclear stellar disc being the grown edge of the nuclear star cluster.Comment: Submitted to A&A. 13 pages, 9 figure