18,937 research outputs found

    Black Hole Monodromy and Conformal Field Theory

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    The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a non-extremal black hole, and it explains why features of the inner event horizon appear in scattering data such as greybody factors. This indicates that hidden conformal symmetry is generic within a universality class of black holes.Comment: 20 pages, v2 minor corrections, updated reference

    The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball Spectroscopy

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    On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyze this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multi-station meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute mag. -10.5) that was simultaneously imaged from three SPMN meteor ob-serving stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration, and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for 5 October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Society. Accepted for publication in MNRAS on April 28th, 2013 Manuscript Pages: 28 Tables: 5 Figures: 12. Manuscript associated: "The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth" by Trigo-Rodriguez et al. is also in press in the same journa

    Black Hole Scattering from Monodromy

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    We study scattering coefficients in black hole spacetimes using analytic properties of complexified wave equations. For a concrete example, we analyze the singularities of the Teukolsky equation and relate the corresponding monodromies to scattering data. These techniques, valid in full generality, provide insights into complex-analytic properties of greybody factors and quasinormal modes. This leads to new perturbative and numerical methods which are in good agreement with previous results.Comment: 28 pages + appendices, 2 figures. For Mathematica calculation of Stokes multipliers, download "StokesNotebook" from https://sites.google.com/site/justblackholes/techy-zon

    Permo-Carboniferous magmatism in the core of Pangaea (Southern Pyreness): a possible linkange between the Variscan and Cimmerian cycles?

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    In southern Europe and the western Mediterranean, Permo-Carboniferous magmatism is well represented in areas of Iberia, the Alps, Sardinia and the Balkan Peninsula. In Iberia, the magmatism that has been related to the Variscan orogeny is associated with syn-orogenic events at ca. 350-315 Ma and post-orogenic at ca. 310-295 Ma. In the southern Pyrenees there is Permo-Carboniferous sedimentary basins with a significant volume of rhyolitic ignimbrites and andesitic flows. The Erill Castell-Estac, Cadí and Castellar de n’Hug basins are spatially associated with the Boí, Montellá and Vielha granites and the Cardet dacitic dykes emplaced in Variscan basement rocks. U-Pb SHRIMP dating of zircons extracted from these granites, an andesitic flow, a dacitic dyke and six ignimbrites, revealed that magmatism was active from ca. 304 Ma to ca. 266 Ma. The scattering of zircon ages in each sample shows that the history of melt crystallization was prolonged and complex. The reported ages of the magmatic activity for the Southern Pyrenees in the range ca. 304-283 Ma (this study) fit in well with the time interval of magmatism related to the early North-dipping subduction of the Western Paleotethys Ocean, the subsequent development of Iberian orocline (Variscan cycle), and the large-scale bending and blocking of the Paleotethys Ocean subduction at East of Iberia.In paleogeographic reconstructions of the Permo-Carboniferous, Iberia is located in the core of Pangaea to the east of the probable Rheic Ocean suture and near the western end of the subduction zone of the Paleotethys Ocean. The emplacement in Iberia of granites with ca. 310-278 Ma age occurred after the collision of Laurussia and Gondwana, when the subduction of the Rheic Ocean was inactive. From a Variscan-cycle perspective, the Permo-Carboniferous magmatism of the Pyrenees has been considered as post-orogenic. However, global paleogeographic reconstructions put Iberia in between the Rheic Ocean suture and the still active subduction zone of the Western Paleotethys Ocean. Therefore, the Permo-Carboniferous magmatism of Iberia, from a Cimmerian-cycle perspective, may have accompanied the closing of the Paleotethys Ocean. During this stage of the evolution of Pangaea, the east of Iberia was geologically affected by the active subduction zone of the Paleotethys Ocean. The period ca. 310-285 Ma is marked by the development of an orocline that extends from Iberia to Armorica. The northwards subduction of the western corner of Paleotethys probably caused orocline formation and consequent large-scale bending and blocking of Paleotethys subduction immediately east of Iberia. The Permo-Carboniferous magmatism of Iberia, coeval with this tectonic evolution, shows a mixed imprint of subduction and delamination geochemical signatures. Although this may seem controversial, in our view the magmatic activity preserved in the Southern Pyrenees could provide the missing link between the development of the Iberian orocline and the continued subduction of easternmost segments of the Paleotethys Ocean (Cimmerian cycle) during the evolution of Pangaea

    The Infrared Astronomical Characteristics of Roque de los Muchachos Observatory: precipitable water vapor statistics

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    The atmospheric water vapor content above the Roque de los Muchachos Observatory (ORM) obtained from Global Positioning Systems (GPS) is presented. GPS measurements have been evaluated by comparison with 940nm-radiometer observations. Statistical analysis of GPS measurements points to ORM as an observing site with suitable conditions for infrared (IR) observations, with a median column of precipitable water vapor (PWV) of 3.8 mm. PWV presents a clear seasonal behavior, being Winter and Spring the best seasons for IR observations. The percentage of nighttime showing PWV values smaller than 3 mm is over 60% in February, March and April. We have also estimated the temporal variability of water vapor content at the ORM. A summary of PWV statistical results at different astronomical sites is presented, recalling that these values are not directly comparable as a result of the differences in the techniques used to recorded the data.Comment: The paper contains 10 figures and 5 tables (28 pages) Accepted by MNRA

    Fossil group origins V. The dependence of the luminosity function on the magnitude gap

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    In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (Δm12\Delta m_{12}). There are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. Fossil and non-fossil systems could have different galaxy populations that should be reflected in their luminosity functions. In this work we study, for the first time, the dependence of the luminosity function parameters on Δm12\Delta m_{12} using data obtained by the fossil group origins (FOGO) project. We constructed a hybrid luminosity function for 102 groups and clusters at z0.25z \le 0.25. We stacked all the individual luminosity functions, dividing them into bins of Δm12\Delta m_{12}, and studied their best-fit Schechter parameters. We additionally computed a relative luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differences, especially at the bright end. We find trends as a function of Δm12\Delta m_{12} at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude MM^\ast. We also find differences at the faint end. In this region, the larger the gap, the flatter the faint-end slope α\alpha. The differences found at the bright end support a dissipationless, dynamical friction-driven merging model for the growth of the central galaxy in group- and cluster-sized halos. The differences in the faint end cannot be explained by this mechanism. Other processes, such as enhanced tidal disruption due to early infall and/or prevalence of eccentric orbits, may play a role. However, a larger sample of systems with Δm12>1.5\Delta m_{12} > 1.5 is needed to establish the differences at the faint end.Comment: 11 pages, 10 figures, accepted for publication in A&
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