Complex Scalar DM in a B-L Model

In this work, we implement a complex scalar Dark Matter (DM) candidate in a $U(1)_{B-L}$ gauge extension of the Standard Model. The model contains three right handed neutrinos with different quantum numbers and a rich scalar sector, with extra doublets and singlets. In principle, these extra scalars can have VEVs ($V_{\Phi}$ and $V_{\phi}$ for the extra doublets and singlets, respectively) belonging to different energy scales. In the context of $\zeta\equiv\frac{V_{\Phi}}{V_{\phi}}\ll1$, which allows to obtain naturally light active neutrino masses and mixing compatible with neutrino experiments, the DM candidate arises by imposing a $Z_{2}$ symmetry on a given complex singlet, $\phi_{2}$, in order to make it stable. After doing a study of the scalar potential and the gauge sector, we obtain all the DM dominant processes concerning the relic abundance and direct detection. Then, for a representative set of parameters, we found that a complex DM with mass around $200$ GeV, for example, is compatible with the current experimental constraints without resorting to resonances. However, additional compatible solutions with heavier masses can be found in vicinities of resonances. Finally, we address the issue of having a light CP-odd scalar in the model showing that it is safe concerning the Higgs and the $Z_{\mu}$ boson invisible decay widths, and also the energy loss in stars astrophysical constraints.Comment: 20 pages, 3 figure

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Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies

We study the spatial distribution of the physical properties and of oxygen and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS 0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate the nature of this excess and, particularly, if it is associated with Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their physical-chemical properties, using both the direct method and appropriate strong-line methods. We make a statistical analysis of the resulting distributions and we compare them with the integrated properties of the galaxies. Our results indicate that outer parts of the three galaxies are placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic diagram most likely due to a high N/O combined with the excitation structure in these regions. From the statistical analysis, it is assumed that a certain property can be considered as spatially homogeneous (or uniform) if a normal gaussian function fits its distribution in several regions of the galaxy. Moreover, a disagreement between the integrated properties and the mean values of the distribution usually appears when a gaussian does not fit the corresponding distribution. We find that for Mrk 930, the uniformity is found for all parameters, except for electron density and reddening. The rotation curve together with the H{\alpha} map and UV images, reveal a perturbed morphology and possible interacting processes. The N/O is found to be constant in the three studied objects at spatial scales of the order of several kpc so we conclude that the number of WR stars estimated from spectroscopy is not sufficient to pollute the ISM and to produce the observed N/O excess in these objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

Tracking ultrafast dynamics by sub-20-fs UV pulses generated in the lab open atmosphere

This study describes a simple method to generate sub-20 fs UV-pulses (264 nm) by third-harmonic generation, in an air-plasma filament formed after focusing the fundamental 800 nm beam directly in the lab open-atmosphere. The generated pulses are applied to track the relaxation through the conical intersection that couples the S2 and S1 states, in the benchmark molecule of naphthalene. The transients, with a resolution of about 25 fs, show two differentiate patterns of quantum beats. The assignation of these oscillations to specific modes in the lower S1 state and to electronic coherence between the two coupled states is discussed

The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey

We analysed the optical spectra of HII regions extracted from a sample of 350 galaxies of the CALIFA survey. We calculated total O/H abundances and, for the first time, N/O ratios using the semi-empirical routine HII-CHI-mistry, which, according to P\'erez-Montero (2014), is consistent with the direct method and reduces the uncertainty in the O/H derivation using [NII] lines owing to the dispersion in the O/H-N/O relation. Then we performed linear fittings to the abundances as a function of the de-projected galactocentric distances. The analysis of the radial distribution both for O/H and N/O in the non-interacting galaxies reveals that both average slopes are negative, but a non-negligible fraction of objects have a flat or even a positive gradient (at least 10\% for O/H and 4\% for N/O). The slopes normalised to the effective radius appear to have a slight dependence on the total stellar mass and the morphological type, as late low-mass objects tend to have flatter slopes. No clear relation is found, however, to explain the presence of inverted gradients in this sample, and there is no dependence between the average slopes and the presence of a bar. The relation between the resulting O/H and N/O linear fittings at the effective radius is much tighter (correlation coefficient $\rho_s$ = 0.80) than between O/H and N/O slopes ($\rho_s$ = 0.39) or for O/H and N/O in the individual \hii\ regions ($\rho_s$ = 0.37). These O/H and N/O values at the effective radius also correlate very tightly (less than 0.03 dex of dispersion) with total luminosity and stellar mass. The relation with other integrated properties, such as star formation rate, colour, or morphology, can be understood only in light of the found relation with mass.Comment: Accepted for publication in A&A. 20 pages, 19 figure

Male song variation of Green Violetear (Colibri thalassinus) in the Talamanca Mountain Range, Costa Rica

We studied variation in acoustic and temporal characteristics of the static male song of the Green Violetear (Colibri thalassinus) in a single population in Costa Rica. The static song of 19 males was extremely variable. The song has two elements: the first was delivered exclusively at the beginning of each song while the second was present once, twice, or three times in the song of different males. Low frequency (LF), song duration (ΔT), and high frequency (HF) varied significantly among most individuals. The male population of Green Violetear has four song types that differ in acoustic and temporal characteristics. The great inter-male song variation suggests this type of vocalization may be under sexual selection.Universidad de Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Eliminating Error in the Chemical Abundance Scale for Extragalactic HII Regions

In an attempt to remove the systematic errors which have plagued the calibration of the HII region abundance sequence, we have theoretically modeled the extragalactic HII region sequence. We then used the theoretical spectra so generated in a double blind experiment to recover the chemical abundances using both the classical electron temperature + ionization correction factor technique, and the technique which depends on the use of strong emission lines (SELs) in the nebular spectrum to estimate the abundance of oxygen. We find a number of systematic trends, and we provide correction formulae which should remove systematic errors in the electron temperature + ionization correction factor technique. We also provide a critical evaluation of the various semi-empirical SEL techniques. Finally, we offer a scheme which should help to eliminate systematic errors in the SEL-derived chemical abundance scale for extragalactic HII regions.Comment: 24 pages, 9 Tables, 13 figures, accepted for publication in MNRAS. Updated considering minor changes during the final edition process and some few missing reference