18,937 research outputs found
Black Hole Monodromy and Conformal Field Theory
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
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
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?
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
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
In nature we observe galaxy aggregations that span a wide range of magnitude
gaps between the two first-ranked galaxies of a system (). 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 using data obtained by the fossil group origins
(FOGO) project. We constructed a hybrid luminosity function for 102 groups and
clusters at . We stacked all the individual luminosity functions,
dividing them into bins of , 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 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 . We also find
differences at the faint end. In this region, the larger the gap, the flatter
the faint-end slope . 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 is
needed to establish the differences at the faint end.Comment: 11 pages, 10 figures, accepted for publication in A&
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