Scalar Field Dark Matter: non-spherical collapse and late time behavior

We show the evolution of non-spherically symmetric balls of a self-gravitating scalar field in the Newtonian regime or equivalently an ideal self-gravitating condensed Bose gas. In order to do so, we use a finite differencing approximation of the Shcr\"odinger-Poisson (SP) system of equations with axial symmetry in cylindrical coordinates. Our results indicate: 1) that spherically symmetric ground state equilibrium configurations are stable against non-spherical perturbations and 2) that such configurations of the SP system are late-time attractors for non-spherically symmetric initial profiles of the scalar field, which is a generalization of such behavior for spherically symmetric initial profiles. Our system and the boundary conditions used, work as a model of scalar field dark matter collapse after the turnaround point. In such case, we have found that the scalar field overdensities tolerate non-spherical contributions to the profile of the initial fluctuation.Comment: 8 revtex pages, 10 eps figures. Accepted for publication in PR

Evolution of a mass-less test scalar field on Boson Stars space-times

We numerically solve the mass-less test scalar field equation on the space-time background of boson stars and black holes. In order to do so, we use a numerical domain that contains future null infinity. We achieve this construction using a scri-fixing conformal compactification technique based on hyperboloidal constant mean curvature foliations of the space-time and solve the conformally invariant wave equation. We present two results: the scalar field shows oscillations of the quasi- normal-mode type found for black holes only for boson star configurations that are compact, and no signs of tail decay is found in the parameter space we explored. Even though our results do not correspond to the master equation of perturbations of boson star solutions, they indicate that the parameter space of boson stars as black hole mimickers is restricted to compact configurations.Comment: 9 pages, 15 eps figures, revtex

A close look into an intermediate redshift galaxy using STIS

We present a detailed view of a galaxy at z=0.4 which is part of a large database of intermediate redshifts using high resolution images. We used the STIS parallel images and spectra to identify the object and obtain the redshift. The high resolution STIS image (0.05'') enabled us to analyse the internal structures of this galaxy. A bar along the major axis and hot-spots of star formation separated by 0.37'' (1.6 kpc) are found along the inner region of the galaxy. The analysis of the morphology of faint galaxies like this one is an important step towards estimating the epoch of formation of the Hubble classification sequence.Comment: Astronomy and Astrophysics Letter - accepte

Scalar Field Dark Matter: head-on interaction between two structures

In this manuscript we track the evolution of a system consisting of two self-gravitating virialized objects made of a scalar field in the newtonian limit. The Schr\"odinger-Poisson system contains a potential with self-interaction of the Gross-Pitaevskii type for Bose Condensates. Our results indicate that solitonic behavior is allowed in the scalar field dark matter model when the total energy of the system is positive, that is, the two blobs pass through each other as should happen for solitons; on the other hand, there is a true collision of the two blobs when the total energy is negative.Comment: 8 revtex pages, 11 eps figures. v2 matches the published version. v2=v1+ref+minor_change

On the Nature of the Strong Emission-Line Galaxies in Cluster Cl 0024+1654: Are Some the Progenitors of Low Mass Spheroidals?

We present new size, line ratio, and velocity width measurements for six strong emission-line galaxies in the galaxy cluster, Cl 0024+1654, at redshift z~0.4. The velocity widths from Keck spectra are all narrow (30<sigma<120 km/s), with three profiles showing double peaks. Four galaxies have low masses (M<10^{10} Mo). Whereas three galaxies were previously reported to be possible AGNs, none exhibit AGN-like emission line ratios or velocity widths. Two or three appear as very blue spirals with the remainder more akin to luminous H-II galaxies undergoing a strong burst of star formation. We propose that after the burst subsides, these galaxies will transform into quiescent dwarfs, and are thus progenitors of some cluster spheroidals (We adopt the nomenclature suggested by Kormendy & Bender (1994), i.e., low-density, dwarf ellipsoidal galaxies like NGC 205 are called `spheroidals' instead of `dwarf ellipticals') seen today.Comment: 14 pages + 2 figures + 1 table, LaTeX, Acc. for publ. in ApJL also available at http://www.ucolick.org/~deep/papers/papers.htm

Shape coexistence in Lead isotopes in the interacting boson model with Gogny energy density functional

We investigate the emergence and evolution of shape coexistence in the neutron-deficient Lead isotopes within the interacting boson model (IBM) plus configuration mixing with microscopic input based on the Gogny energy density functional (EDF). The microscopic potential energy surface obtained from the constrained self-consistent Hartree-Fock-Bogoliubov method employing the Gogny-D1M EDF is mapped onto the coherent-state expectation value of the configuration-mixing IBM Hamiltonian. In this way, the parameters of the IBM Hamiltonian are fixed for each of the three relevant configurations (spherical, prolate and oblate) associated to the mean field minima. Subsequent diagonalization of the Hamiltonian provides the excitation energy of the low-lying states and transition strengths among them. The model predictions for the $0^{+}$ level energies and evolving shape coexistence in the considered Lead chain are consistent both with experiment and with the indications of the Gogny-EDF energy surfaces.Comment: 12 pages, 6 figures, 1 tabl

Analysis Of The Cyclability Of Lithium-polymer Batteries

Comunicación y póster en congresoLithium ion batteries and similar energy storage devices have an increasing importance for the modern society as they are present in many portable electronic devices and have perspectives in the fields of electric vehicles and renewable energy accumulation. Herein, we present results from charge and discharge cycles on batteries under controlled conditions. The cyclability of commercial lithium-polymer pouch batteries under different charge/discharge rates and temperatures was studied. Based on the results, the relationship between the state of charge and the cell voltage was obtained, as well as degradation of the cells, i.e., the decrease of the energy capacity after a number of cycles. The experimental results were compared with simulations based on Newman's model for Lithium Ion Batteries, carried out using the COMSOL Multiphysics® software. The batteries and fuel cell and the heat transfer modules were use to couple between the temperature and the electrochemical interactions. The results show the correlation between temperature, C-rate and degradation in lithium ion batteries. It is specially remarkable the decrease of the apparent capacity of batteries at low temperatures, and the increase of the degradation at higher temperatures. These results are essential for the design of mechanisms that could prevent battery failure.The authors acknowledge the financial support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045, and the "Plan Propio de Investigación y Transferencia de la Universidad de Málaga", code: PPIT.UMA.B5.2018/17

Diffusion of fluorine adatoms on doped graphene

We calculate the diffusion barrier of fluorine adatoms on doped graphene in the diluted limit using Density Functional Theory. We found that the barrier $\Delta$ strongly depends on the magnitude and character of the graphene's doping ($\delta n$): it increases for hole doping ($\delta n<0$) and decreases for electron doping ($\delta n>0$). Near the neutrality point the functional dependence can be approximately by $\Delta=\Delta_0-\alpha\, \delta n$ where $\alpha\simeq6\times10^{-12}$ meVcm$^2$. This effect leads to significant changes of the diffusion constant with doping even at room temperature and could also affect the low temperature diffusion dynamics due to the presence of substrate induced charge puddles. In addition, this might open up the possibility to engineer the F dynamics on graphene by using local gates.Comment: 4 pages, 4 figure

Gate induced enhancement of spin-orbit coupling in dilute fluorinated graphene

We analyze the origin of spin-orbit coupling (SOC) in fluorinated graphene using Density Functional Theory (DFT) and a tight-binding model for the relevant orbitals. As it turns out, the dominant source of SOC is the atomic spin-orbit of fluorine adatoms and not the impurity induced SOC based on the distortion of the graphene plane as in hydrogenated graphene. More interestingly, our DFT calculations show that SOC is strongly affected by both the type and concentrations of the graphene's carriers, being enhanced by electron doping and reduced by hole doping. This effect is due to the charge transfer to the fluorine adatom and the consequent change in the fluorine-carbon bonding. Our simple tight-binding model, that includes the SOC of the $2p$ orbitals of F and effective parameters based on maximally localized Wannier functions, is able to account for the effect. The strong enhancement of the SOC induced by graphene doping opens the possibility to tune the spin relaxation in this material.Comment: 9 pages, 8 figure