Examinando por Autor "Motta, Verónica"
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Ítem Dissecting the Strong-lensing Galaxy Cluster MS 0440.5+0204. I. The Mass Density Profile(The American Astronomical Society, 2020) Foëx, Gael; Motta, VerónicaWe present a parametric strong-lensing modeling of the galaxy cluster MS 0440.5+0204 (located at z = 0.19). We have performed a strong-lensing mass reconstruction of the cluster using three different models. The first model uses the image positions of four multiply imaged systems (providing 26 constraints). The second one combines strong-lensing constraints with dynamical information (velocity dispersion) of the cluster. The third one uses the mass calculated from weak lensing as an additional constraint. Our three models reproduce equally well the image positions of the arcs, with an rms image equal to ≈0farcs5. However, in the third model, the inclusion of the velocity dispersion and the weak-lensing mass allows us to obtain better constraints in the scale radius and the line-of-sight velocity dispersion of the mass profile. For this model, we obtain rs = ${132}_{-32}^{+30}$ kpc, ${\sigma }_{s}={1203}_{-47}^{+46}$ km s−1, M200 = ${3.1}_{-0.6}^{+0.6}$ ×1014 ${M}_{\odot }$, and a high concentration c200 = ${9.9}_{-1.4}^{+2.2}$. Finally, we used our derived mass profile to calculate the mass up to 1.5 Mpc. We compare it with X-ray estimates previously reported, finding a good agreement.Ítem Dissecting the Strong-lensing Galaxy Cluster MS0440.5+0204. II. New Optical Spectroscopic Observations in a Wider Area and Cluster Dynamical State(American Astronomical Society (Aas), 2021) Carrasco, Eleazar R.; Verdugo, Tomás; Motta, Verónica; Foëx, Gael; Ellingson, E.; Gomez, Percy L.; Falco, Emilio; Limousin, MarceauWe present an optical study of the strong-lensing galaxy cluster MS 0440.5+0204 at z = 0.19593, based on CFHT/MegaCam g', r' photometry and GMOS/Gemini and CFHT/MOS/SIS spectroscopy in a broader area than previous works. We have determined new spectroscopic redshifts for the most prominent gravitational arcs surrounding the central galaxy in the cluster. The new redshifts and the information provided by the photometric catalog allow us to perform a detailed weak- and strong-lensing mass reconstruction of the cluster. The large number of member galaxies and the area covered by our observations allow us to estimate more accurately the velocity dispersion and mass of the cluster and to examine in detail the nature of the cluster and surrounding structures. The dynamical mass is in good agreement with the mass inferred from the lensing analysis and X-ray estimates. About 68% of the galaxies are located in the inner ≲0.86 ${h}_{70}^{-1}$ Mpc region of the cluster. The galaxy redshift distribution in the inner region of the cluster shows a complex structure with at least three substructures along the line of sight. Other substructures are also identified in the galaxy density map and in the weak-lensing mass map. The member galaxies in the northeast overdensity are distributed in a filament between the clusters MS 0440.5+0204 and ZwCL 0441.1+0211, suggesting that these two structures might be connected. MS 0440.5+0204 appears to be dynamically active, with a cluster core that is likely experiencing a merging process, and with other nearby groups at projected distances of ≲1 ${h}_{70}^{-1}$ Mpc that could be being accreted by the cluster.Ítem Estimación del efecto microlente cromático en los sistemas QSO2237+0305 y SDSS1226-0006(Universidad de Valparaíso, 2022-04) Jerez Nicurcar, Ramsés; Motta, VerónicaEl efecto lente gravitacional es una poderosa herramienta que permite estudiar la estructura interna de los núcleos activos de galaxias. Este proceso es posible de realizar debido a que estas fuentes lejanas son magnificadas, accediendo a una resolución angular que de otra manera no sería posible. En esta tesis de magíster, se estudiaron los siguientes objetos lentes gravitacionales: el sistema cuádruple QSO2237+0305 (cruz de Einstein) y el sistema doble SDSS1226-0006. El primero concita gran interés debido a que la galaxia lente se encuentra a un corrimiento al rojo muy cercano. En el segundo sistema se han realizado escasos estudios, los cuales están relacionado con la distribución de materia de la galaxia lente, no habiéndose hecho estimaciones de los parámetros del disco de acreción con anterioridad. Mediante el estudio del espectro de cada imagen lentificada, se han analizado las líneas de emisión y continuo bajo éstas, así como también, se ha cuestionado la existencia de extinción en las líneas de emisión del sistema QSO2237+0305 obtenida en la literatura. Junto a este análisis, se ha encontrado efecto microlente en la región de las líneas anchas. Se ha confirmado la existencia de efecto microlente cromático entre las imágenes de los sistemas, permitiendo modelar el disco de acreción con un perfil de temperatura ( p). Dado a que existe una dependencia en la longitud de onda, es posible parametrizarla, de modo que el tamaño del disco de acreción se puede escribir siguiendo una ley de potencia, mediante la relación rs ∝ λp, donde p corresponde al perfil de temperatura. Se han encontrado los tamaños de los discos medidos a λ = 1026 Å y los perfiles de temperatura.Ítem Microlensing Analysis for the Gravitational Lens Systems SDSS0924+0219, Q1355-2257, and SDSS1029+2623(The American Astronomical Society, 2020) Rojas, Karina; Motta, VerónicaWe use spectroscopic observations of the gravitationally lensed systems SDSS0924+0219(BC), Q1355-2257(AB), and SDSS1029+2623(BC) to analyze microlensing and dust extinction in the observed components. We detect chromatic microlensing effects in the continuum and microlensing in the broad emission line profiles of the systems SDSS0924+0219(BC) and Q1355-2257(AB). Using magnification maps to simulate microlensing and modeling the emitting region as a Gaussian intensity profile with size rs ∝ λp, we obtain the probability density functions for a logarithmic size prior to ‐ Å lrest frame = 3533 . In the case of SDSS0924+0219, we obtain = - r 4+ M M s 2 3 lt-d (at 1σ), which is larger than the range of other estimates, and p=0.8±0.2 (at 1σ), which is smaller than predicted by the thin disk theory, but still in agreement with previous results. In the case of Q1355- 2257 we obtain (at 1σ) = - r 3.6+ M M s 1.6 3.0 lt-d, which is also larger than the theoretical prediction, and p=2.0±0.7, which is in agreement with the theory within errors. SDSS1029+2326 spectra show evidence of extinction, probably produced by a galaxy in the vicinity of image C. Fitting an extinction curve to the data we estimate ΔE∼0.2 in agreement with previous results. We found no evidence of microlensing for this systemÍtem Stability analysis and constraints on interacting viscous cosmology(American Physical Society, 2020) Motta, VerónicaIn this work we study the evolution of a spatially flat Universe by considering a viscous dark matter and perfect fluids for dark energy and radiation, including an interaction term between dark matter and dark energy. In the first part, we analyse the general properties of the Universe by performing a stability analysis and then we constrain the free parameters of the model using the latest and cosmological-independent measurements of the Hubble parameter. We find consistency between the viscosity coefficient and the condition imposed by the second law of the Thermodynamics. The second part is dedicated to constrain the free parameter of the interacting viscous model (IVM) for three particular cases: the viscous model (VM), interacting model (IM), and the perfect fluid case (the concordance model). We report the deceleration parameter to be q0=−0.54+0.06−0.05, −0.58+0.05−0.04, −0.58+0.05−0.05, −0.63+0.02−0.02, together with the jerk parameter as j0=0.87+0.06−0.09, 0.94+0.04−0.06, 0.91+0.06−0.10, 1.0 for the IVM, VM, IM, and LCDM respectively, where the uncertainties correspond at 68\% CL. Worth mentioning that all the particular cases are in good agreement with LCDM, in some cases producing even better fits, with the advantage of eliminating some problems that afflicts the standard cosmological model.Ítem Strong gravitational lensing as a probe of structure from small to large scale(Universidad de Valparaíso, 2018-07) Rojas Olate, Karina; Motta, VerónicaThe gravitational lens effect occurs when the light is deflected by a gravitational field, generating multiple images or arcs. This powerful technique allows us to study structures at different scales in the universe that are usually related to different astrophysical problems. For instance, the characterization of dark objects in our galaxy (structure and mass distribution), the compact objects in the galaxy halos, the inner structure of quasars. Furthermore, it can be used to probe the cosmological model, for example through estimations of the Hubble constant (H0) and the mass distribution profile in galaxies, groups and cluster of galaxies. In this work I studied different structures that are affected or produced by grav- itational effect. In our galaxy at interstellar scale, I searched for microlensing effects in a region of the VISTA Variable in the V´ıa L´actea Survey (VVV). At galaxy-size scale, I studied the microlensing effect in lensed quasars to estimate the size (rs) and temperature profile (p) of their accretion disks and the effect of microlensing on time delay (∆t) measurements (related to H0). At cosmological scales, I performed a dynamical analysis for groups and clusters of galaxies to finally study the mass distribution profile in their halos. To reach these objectives I used visual and infrared images, spectroscopic data, models and simulations. The results presented in this thesis have been published in Rojas et al. (2014); Minniti et al. (2015); Verdugo et al. (2016); Motta et al. (2017); Courbin et al. (2018); Bonvin et al. (2018) among others, and part of the work is in preparation to be publish in Rojas et al. in prep(a,b), among others.Ítem Taxonomy of Dark Energy Models(MDPI, 2021) Motta, Verónica; García-Aspeitia, Miguel A.; Hernández-Almada, Alberto; Magaña, Juan; Verdugo, TomásThe accelerated expansion of the Universe is one of the main discoveries of the past decades, indicating the presence of an unknown component: the dark energy. Evidence of its presence is being gathered by a succession of observational experiments with increasing precision in its measurements. However, the most accepted model for explaining the dynamic of our Universe, the so-called Lambda cold dark matter, faces several problems related to the nature of such energy component. This has led to a growing exploration of alternative models attempting to solve those drawbacks. In this review, we briefly summarize the characteristics of a (non-exhaustive) list of dark energy models as well as some of the most used cosmological samples. Next, we discuss how to constrain each model’s parameters using observational data. Finally, we summarize the status of dark energy modeling.Ítem TDCOSMO(European Southern Observatory, 2020) Motta, VerónicaTime-delay cosmography of lensed quasars has achieved 2.4% precision on the measurement of the Hubble constant, H0. As part of an ongoing effort to uncover and control systematic uncertainties, we investigate three potential sources: 1- stellar kinematics, 2- line-of-sight effects, and 3- the deflector mass model. To meet this goal in a quantitative way, we reproduced the H0LiCOW/SHARP/STRIDES (hereafter TDCOSMO) procedures on a set of real and simulated data, and we find the following. First, stellar kinematics cannot be a dominant source of error or bias since we find that a systematic change of 10% of measured velocity dispersion leads to only a 0.7% shift on H0 from the seven lenses analyzed by TDCOSMO. Second, we find no bias to arise from incorrect estimation of the line-of-sight effects. Third, we show that elliptical composite (stars + dark matter halo), power-law, and cored power-law mass profiles have the flexibility to yield a broad range in H0 values. However, the TDCOSMO procedures that model the data with both composite and power-law mass profiles are informative. If the models agree, as we observe in real systems owing to the “bulge-halo” conspiracy, H0 is recovered precisely and accurately by both models. If the two models disagree, as in the case of some pathological models illustrated here, the TDCOSMO procedure either discriminates between them through the goodness of fit, or it accounts for the discrepancy in the final error bars provided by the analysis. This conclusion is consistent with a reanalysis of six of the TDCOSMO (real) lenses: the composite model yields H0 = 74.0−1.8+1.7 km s−1 Mpc−1, while the power-law model yields 74.2−1.6+1.6 km s−1 Mpc−1. In conclusion, we find no evidence of bias or errors larger than the current statistical uncertainties reported by TDCOSMO.Ítem TDCOSMO(European Southern Observatory, 2020) Motta, Verónica; Melo, AlejandraWe present six new time-delay measurements obtained from Rc-band monitoring data acquired at the Max Planck Institute for Astrophysics (MPIA) 2.2 m telescope at La Silla observatory between October 2016 and February 2020. The lensed quasars HE 0047−1756, WG 0214−2105, DES 0407−5006, 2M 1134−2103, PSJ 1606−2333, and DES 2325−5229 were observed almost daily at high signal-to-noise ratio to obtain high-quality light curves where we can record fast and small-amplitude variations of the quasars. We measured time delays between all pairs of multiple images with only one or two seasons of monitoring with the exception of the time delays relative to image D of PSJ 1606−2333. The most precise estimate was obtained for the delay between image A and image B of DES 0407−5006, where τAB = −128.4−3.8+3.5 d (2.8% precision) including systematics due to extrinsic variability in the light curves. For HE 0047−1756, we combined our high-cadence data with measurements from decade-long light curves from previous COSMOGRAIL campaigns, and reach a precision of 0.9 d on the final measurement. The present work demonstrates the feasibility of measuring time delays in lensed quasars in only one or two seasons, provided high signal-to-noise ratio data are obtained at a cadence close to daily.