122883156
Gauge field localization on a dilatonic deformed brane
Abstract Membranes with internal structures presents several important characteristics in brane world scenarios. In this context we give new results in the study of localization of gauge vector fields in a very specific kink-like solution. We analyze, in particular, the coupling produced by the dilaton field in the space–time background. We find resonance structures in the KK spectrum revealing interesting behavior of coupling between massive states and matter localized in the membrane.
16040629
Generating mass and topological terms to the antisymmetric tensor matter field by Higgs mechanism
The interaction between the complex antisymmetric tensor matter field and a scalar field is constructed. We analyze the Higgs mechanism and show the generation of mass and topological terms by spontaneous symmetry breaking.
118334880
Resonances on deformed thick branes
In this work we investigate the issue of gravity and fermion localization and resonances in $(4,1)$-branes constructed with one scalar field coupled with gravity in deformed models. Such models give solutions for the scalar field that is the usual kink solution in the extra dimension for a parameter $p=1$ and deformations with a two-kink profile for odd $p>1$. Gravity is localized and resonant modes are found for small values of $p$. The coupling between the scalar field and spinors is a necessary condition for fermions to be localized on such branes. After performing a chiral decomposition of the five-dimensional spinor we found resonances with both chiralities for all odd $p$'s. The correspondence between the spectra for left and right chirality is guaranteed and Dirac fermions are realized on the brane. The increasing of $p$ characterizes the formation of branes with internal structure that turns the gravitational interaction more effective for fermions aside the brane, increasing their lifetime. The influence of the internal structure of the branes and the presence of resonances for gravity and fermionic modes is addressed.
123618108
TOPOLOGICAL AND EQUIVALENT MODELS ON BRANE-WORLDS
In this work we obtain topological and equivalent theories on brane-worlds in several dimensions. Our brane is a solitonic-like hypersurface embedded in a spacetime with a specific dimensionality and it appears due to the breaking of a Peccei–Quinn-like symmetry. In the first part of this work, the obtained topological theories are related to a generalization of the axion–photon anomalous interaction in D = 4 (in the Abelian case) and to the Wess–Zumino term (in the non-Abelian case). In the second part, we construct equivalent models on the brane through a mechanism of explicit Lorentz symmetry breaking. The gauge symmetries of such models are discussed within the Stuckelberg formalism.
120573076
FORM OF THE QUANTUM KINETIC-ENERGY OPERATOR WITH SPATIALLY VARYING EFFECTIVE MASS
118759367
Generalized axion-photon couplings and dual descriptions on brane-worlds
In this work we obtain topological and dual theories on brane-worlds in several dimensions. Our brane is a solitonic-like hypersurface embedded in a space-time with a specific dimensionality and it appears due to the breaking of a Peccei-Quinn-like symmetry. In the first part of this work, the obtained topological theories are related to a generalization of the axion-foton anomalous interaction in D=4 (in the Abelian case) and to the Wess-Zumino term (in the non-Abelian case). In the second part, we construct dual models on the brane through a mechanism of explicit Lorentz symmetry breaking. The gauge symmetries of such models are discussed within the Stuckelberg formalism.
73697143
Spitzer Mid-IR Spectroscopy of Powerful 2?Jy and 3CRR Radio Galaxies. I. Evidence against a Strong Starburst-AGN Connection in Radio-loud AGN
We present deep Spitzer/Infrared Spectrograph (IRS) spectra for complete samples of 46 2 Jy radio galaxies (0.05 75%) than their more extended counterparts (≈15%-25%). We discuss this result in the context of a possible bias toward the selection of compact radio sources triggered in gas-rich environments.
118465353
Testing the AGN Unification Model in the Infrared
We present near-to-mid-infrared spectral energy distributions (SEDs) for 21 Seyfert galaxies, using subarcsecond resolution imaging data. Our aim is to compare the properties Seyfert 1 (Sy1) and Seyfert 2 (Sy2) tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) nuclear SEDs. These dusty tori have physical sizes smaller than 6 pc radius, as derived from our fits. Active galactic nuclei (AGN) unification schemes account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold, and that the immediate dusty surroundings of Sy1 and Sy2 nuclei are intrinsically different. The Type 2 tori studied here are broader, have more clumps, and these clumps have lower optical depths than those of Type 1 tori. The larger the covering factor of the torus, the smaller the probability of having direct view of the AGN, and vice-versa. In our sample, Sy2 tori have larger covering factors (CT = 0.95±0.02) and smaller escape probabilities than those of Sy1 (CT = 0.5±0.1). Thus, on the basis of the results presented here, the classification of a Seyfert galaxy may depend more on the intrinsic properties of the torus rather than on its mere inclination, in contradiction with the simplest unification model.
118514386
The Mid-Infrared Emission of Seyfert Galaxies: A New Analysis of ISOCAM Data
We present mid-infrared data of a sample of 57 AGNs obtained with the instrument ISOCAM on board the Infrared Space Observatory (ISO) satellite. The images were obtained through the LW2 (6.75 μm) and LW7 (9.62 μm) filters. This is a new analysis of the Clavel et al. galaxy sample, which is divided into 26 type 1 (≤1.5) and 28 type 2 (>1.5) Seyfert galaxies, plus three QSOs. The spatial resolution of the images allows us to separate the nuclear and the extended contributions to the total emission after decomposing the brightness profiles into different morphological components. The most common components are a central point source (identified as the active nucleus) and an exponential disk. In some cases a bulge, a bar, or a ring are needed. The relative contribution of the nucleus to the total emission appears larger in Seyfert 1 than in Seyfert 2 types. This result confirms that both types of Seyfert galaxies are different in the mid-infrared wavelength range and supports the existence of a structure which produces anisotropic emission in this wavelength range. We have also explored correlations between the mid-infrared and the radio and X-ray wavelength ranges. The well-established radio/infrared correlation is maintained in our sample for the global emission of the galaxies. If only the nuclear infrared emission is considered, then a nonlinear correlation is apparent in the luminosity-luminosity scatter diagram. The ratio between the intrinsic hard X-ray and the nuclear mid-infrared emission presents large scatter and slightly larger values for type 2 Seyfert galaxies. These results seem to be consistent with the presence of a clumpy dusty torus surrounding the active nucleus.
14220887
The Narrow-Line Region of the Seyfert 2 Galaxy Mrk 78: An Infrared View
We report near-infrared spectroscopic data for the Seyfert 2 galaxy Mrk 78, taken with the LIRIS near-infrared camera/spectrometer at the William Herschel Telescope (WHT). The long-slit spectra clearly show extended emission. The resolution and depth of the near-infrared spectra allow the examination of its morphology and ionization regions, and a direct comparison with similarly deep visible spectra. The emission-line ratios obtained are used to derive the extinction toward the nucleus. The detection of strong features such as [Fe II], H2, hydrogen recombination lines, and the coronal [Si VI] λ1.962 line is used to study the kinematics and excitation mechanisms occurring in Mrk 78, revealing that despite the strong radio-jet interaction present in this object, photoionization from the active nucleus dominates the narrow-line region emission, while UV fluorescence is the source of the H2 emission. Lines with extended emission yield velocity distributions with an amplitude of about 600 km s-1, the consequence of an eastern lobe moving away from us plus a western lobe with the opposite contribution. We used the photoionization code CLOUDY to recreate a typical narrow-line region, to derive the ionization parameter, and to compare our spectral data with diagnostic diagrams.