Characterisation of a candidate dual AGN

We present Chandra and optical observations of a candidate dual AGN discovered serendipitously while searching for recoiling black holes via a cross-correlation between the serendipitous XMM source catalog (2XMMi) and SDSS-DR7 galaxies with a separation no larger than ten times the sum of their Petrosian radii. The system has a stellar mass ratio M$_{1}$/M$_{2}\approx 0.7$. One of the galaxies (Source 1) shows clear evidence for AGN activity in the form of hard X-ray emission and optical emission-line diagnostics typical of AGN ionisation. The nucleus of the other galaxy (Source 2) has a soft X-ray spectrum, bluer colours, and optical emission line ratios dominated by stellar photoionisation with a "composite" signature, which might indicate the presence of a weak AGN. When plotted on a diagram with X-ray luminosity vs [OIII] luminosity both nuclei fall within the locus defined by local Seyfert galaxies. From the optical spectrum we estimate the electron densities finding n$_{1} < 27$ e$^{-}$ cm$^{-3}$ and n$_{2} \approx 200$ e$^{-}$ cm$^{-3}$. From a 2D decomposition of the surface brightness distribution we infer that both galaxies host rotationally supported bulges (Sersic index $< 1$). While the active nature of Source 1 can be established with confidence, whether the nucleus of Source 2 is active remains a matter of debate. Evidence that a faint AGN might reside in its nucleus is, however, tantalising.Comment: 16 pages, 9 figures. Accepted for publication on MNRAS. Comments welcom

Sinopsis de las Asteraceae de la Provincia de Catamarca

Fil: Freire, Susana Edith. Instituto de Botánica Darwinion. Buenos Aires; ArgentinaFil: Bayón, Néstor D.. Área de Botánica, Departamento de Ciencias Biológica Facultad de Ciencias Agrarias y Forestales. Universidad Nacional de La Plata; ArgentinaFil: Monti, Claudia. Área de Botánica. Departamento de Ciencias Biológica. Facultad de Ciencias Agrarias y Forestales. Universidad Nacional de La Plata; ArgentinaFil: Giuliano, Daniel A.. Área de Botánica. Departamento de Ciencias Biológica. Facultad de Ciencias Agrarias y Forestales. Universidad Nacional de La Plata; ArgentinaFil: Ariza Espinar, Luis. Museo Botánico. Facultad de Ciencias Exactas, Físicas y Naturales. Universidad Nacional de Córdoba; ArgentinaFil: Sáenz, Alcides A.. División Plantas Vasculares. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Perea, Mario V.. Facultad de Ciencias Exactas y Naturales (UNCA). San Fernando del Valle de Catamarca; ArgentinaFil: Delucchi, Gustavo. División Plantas Vasculares. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Parabolic stable surfaces with constant mean curvature

We prove that if u is a bounded smooth function in the kernel of a nonnegative Schrodinger operator $-L=-(\Delta +q)$ on a parabolic Riemannian manifold M, then u is either identically zero or it has no zeros on M, and the linear space of such functions is 1-dimensional. We obtain consequences for orientable, complete stable surfaces with constant mean curvature $H\in\mathbb{R}$ in homogeneous spaces $\mathbb{E}(\kappa,\tau)$ with four dimensional isometry group. For instance, if M is an orientable, parabolic, complete immersed surface with constant mean curvature H in $\mathbb{H}^2\times\mathbb{R}$, then $|H|\leq 1/2$ and if equality holds, then M is either an entire graph or a vertical horocylinder.Comment: 15 pages, 1 figure. Minor changes have been incorporated (exchange finite capacity by parabolicity, and simplify the proof of Theorem 1)

Experimental analysis of optimization techniques on the road passenger transportation problem

Analyzing the state of the art in a given field in order to tackle a new problem is always a mandatory task. Literature provides surveys based on summaries of previous studies, which are often based on theoretical descriptions of the methods. An engineer, however, requires some evidence from experimental evaluations in order to make the appropriate decision when selecting a technique for a problem. This is what we have done in this paper: experimentally analyzed a set of representative state-of-the-art techniques in the problem we are dealing with, namely, the road passenger transportation problem. This is an optimization problem in which drivers should be assigned to transport services, fulfilling some constraints and minimizing some function cost. The experimental results have provided us with good knowledge of the properties of several methods, such as modeling expressiveness, anytime behavior, computational time, memory requirements, parameters, and free downloadable tools. Based on our experience, we are able to choose a technique to solve our problem. We hope that this analysis is also helpful for other engineers facing a similar proble

An overdetermined eigenvalue problem and the Critical Catenoid conjecture

We consider the eigenvalue problem $\Delta^{\mathbb{S}^2} \xi + 2 \xi=0$ in $\Omega$ and $\xi = 0$ along $\partial \Omega$, being $\Omega$ the complement of a disjoint and finite union of smooth and bounded simply connected regions in the two-sphere $\mathbb{S}^2$. Imposing that $|\nabla \xi|$ is locally constant along $\partial \Omega$ and that $\xi$ has infinitely many maximum points, we are able to classify positive solutions as the rotationally symmetric ones. As a consequence, we obtain a characterization of the critical catenoid as the only embedded free boundary minimal annulus in the unit ball whose support function has infinitely many critical points