Departamento de Física
URI permanente para esta comunidadhttps://hdl.handle.net/10953/33
En esta Comunidad se recogen los documentos generados por el Departamento de Física y que cumplen los requisitos de Copyright para su difusión en acceso abierto.
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Examinando Departamento de Física por Autor "Battaner, Eduardo"
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Ítem Magnetic fields as an alternative explanation for the rotation curves of spiral galaxies(Springer Nature, 1992-12) Battaner, Eduardo; Garrido, J.L.; Membrado, Manuel; Florido, EstrellaThe flat rotation curves of spiral galaxies are usually regarded as the most convincing evidence for dark matter. The assumption that gravity alone is responsible for the motion of gas beyond the visible disks of galaxies leads directly to the conclusion that there must be perhaps 10 times as much dark matter as visible matter. Other forces besides gravity are usually neglected, as order-of-magnitude arguments seem to suggest they cannot be important. The existence of dark matter is, however, so important an issue that we believe it is wise to consider other possibilities. Here we argue that an azimuthal magnetic field can carry slightly ionized gas with the general galactic rotation, rendering dark matter unnecessary (a related idea was first proposed by Nelson1). For the illustrative case of M31, a magnetic field of 6 μG is required, and the synchrotron emission of relativistic electrons in this field is compatible with the observations.Ítem Magnetic fields in the Milky Way neighbouhood as deduced from WARPS in inspiral galaxies(EDP Sciences, 1991-11) Battaner, Eduardo; Garrido, J.L.; Sánchez-Saavedra, Maria Luisa; Florido, EstrellaIt is shown that warps of spiral galaxies are not randomly oriented in the Milky Way neighbourhood. By adopting a previous model, in which warps are produced by intergalactic magnetic fields, and considering all northern hemisphere warped edge-on NGC spiral galaxies, an analysis of the intergalactic magnetic field in the 100 Mpc neighbourhood of our Galaxy is carried out. At the 100 Mpc scale the magnetic field is still rather homogeneous, having a direction given by (alpha = 289 degrees, delta = 8 degrees), but a characteristic scale of about 25 Mpc is found, inside which the dispersion is very low. The region containing the Virgo Cluster has a direction of the magnetic field different from the direction found in adjacent regions.Ítem On the coherent orientation of spins of spiral galaxies(EDP Sciences, 1993-04) Garrido, J.L.; Battaner, Eduardo; Sánchez-Saavedra, Maria Luisa; Florido, EstrellaThe method of convergence of planes developed by Battaner et al. (1991, hereafter BGSF) has been used for investigating coherent alignments of rotation axes of spiral galaxies in the Milky Way neighbourhood. Results are contrasted with previous analyses carried out by other means, taking into account that they were not conclusive either to confirm or to reject coherent alignments. Some improvements of the method are described. No evidence for coherent alignments has been found here, with the exception of some zones, in particular that around the Coma supercluster in which the angular momentum vectors tend to be perpendicular to the axis of the Coma supercluster.