Twinlike Models for Self-Dual Maxwell-Higgs Theories

In this work we present a theoretical framework that allows for the existence of coherent twinlike models in the context of self-dual Maxwell-Higgs theories. We verify the consistence of this framework by using it to develop some twinlike self-dual Maxwell-Higgs models. We use a combination of theoretical and numerical techniques to show that these models exhibit the very same topological BPS structures, including their field configurations and total energy. The study shows that it is possible to develop a completely consistent prescription, which extends the idea of twinlike models to the case of vortices in Maxwell-Higgs theories.Comment: 7 pages, 3 figures; version to appear in PR

Identification of a high-velocity compact nebular filament 2.2 arcsec south of the Galactic Centre

The central parsec of the Milky Way is a very special region of our Galaxy; it contains the supermassive black hole associated with Sgr A* as well as a significant number of early-type stars and a complex structure of streamers of neutral and ionized gas, within two parsecs from the centre, representing a unique laboratory. We report the identification of a high velocity compact nebular filament 2.2 arcsec south of Sgr A*. The structure extends over ~1 arcsec and presents a strong velocity gradient of ~200 km s^{-1} arcsec^{-1}. The peak of maximum emission, seen in [Fe III] and He I lines, is located at d{\alpha} = +0.20 +/- 0.06 arcsec and d{\delta} = -2.20 +/- 0.06 arcsec with respect to Sgr A*. This position is near the star IRS 33N. The velocity at the emission peak is Vr = -267 km s^{-1}. The filament has a position angle of PA = 115{\degr} +/- 10{\degr}, similar to that of the Bar and of the Eastern Arm at that position. The peak position is located 0.7 arcsec north of the binary X-ray and radio transient CXOGX J174540.0-290031, a low-mass X-ray binary with an orbital period of 7.9 hr. The [Fe III] line emission is strong in the filament and its vicinity. These lines are probably produced by shock heating but we cannot exclude some X-ray photoionization from the low-mass X-ray binary. Although we cannot rule out the idea of a compact nebular jet, we interpret this filament as a possible shock between the Northern and the Eastern Arm or between the Northern Arm and the mini-spiral "Bar".Comment: 7 pages, 4 figures, published online in MNRA

NGC 7097: the AGN and its mirror, revealed by PCA Tomography

Three-dimensional (3D) spectroscopy techniques are becoming more and more popular, producing an increasing number of large data cubes. The challenge of extracting information from these cubes requires the development of new techniques for data processing and analysis. We apply the recently developed technique of Principal Component Analysis (PCA) Tomography to a data cube from the center of the elliptical galaxy NGC 7097 and show that this technique is effective in decomposing the data into physically interpretable information. We find that the first five principal components of our data are associated with distinct physical characteristics. In particular, we detect a LINER with a weak broad component in the Balmer lines. Two images of the LINER are present in our data, one seen through a disk of gas and dust, and the other after scattering by free electrons and/or dust particles in the ionization cone. Furthermore, we extract the spectrum of the LINER, decontaminated from stellar and extended nebular emission, using only the technique of PCA Tomography. We anticipate that the scattered image has polarized light, due to its scattered nature.Comment: 12 pages, 5 figures, accepted for publication in ApJ Letter

Thermal Radiation from a Fluctuating Event Horizon

We consider a pointlike two-level system undergoing uniformly accelerated motion. We evaluate the transition probability for a finite time interval of this system coupled to a massless scalar field near a fluctuating event horizon. Horizon fluctuations are modeled using a random noise which generates light-cone fluctuations. We study the case of centered, stationary and Gaussian random processes. The transition probability of the system is obtained from the positive-frequency Wightman function calculated to one loop order in the noise averaging process. Our results show that the fluctuating horizon modifies the thermal radiation but leaves unchanged the temperature associated with the acceleration.Comment: 8 pages, 3 figure

IFU spectroscopy of 10 early type galactic nuclei: II - Nuclear emission line properties

Although it is well known that massive galaxies have central black holes, most of them accreting at low Eddington ratios, many important questions still remain open. Among them, are the nature of the ionizing source, the characteristics and frequencies of the broad line region and of the dusty torus. We report observations of 10 early-type galactic nuclei, observed with the IFU/GMOS spectrograph on the Gemini South telescope, analysed with standard techniques for spectral treatment and compared with results obtained with principal component analysis Tomography (Paper I). We performed spectral synthesis of each spaxel of the data cubes and subtracted the stellar component from the original cube, leaving a data cube with emission lines only. The emission lines were decomposed in multi-Gaussian components. We show here that, for eight galaxies previously known to have emission lines, the narrow line region can be decomposed in two components with distinct line widths. In addition to this, broad H$\alpha$ emission was detected in six galaxies. The two galaxies not previously known to have emission lines show weak H$\alpha$+[N II] lines. All 10 galaxies may be classified as low-ionization nuclear emission regions in diagnostic diagrams and seven of them have bona fide active galactic nuclei with luminosities between 10$^{40}$ and 10$^{43}$ erg s$^{-1}$. Eddington ratios are always < 10$^{-3}$.Comment: 16 pages, 9 figures, accepted for publication in MNRA