Examinando por Autor "Motta, V."
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Ítem A hybrid model of viscous and Chaplygin gas to tackle the Universe acceleration(Springer, 2021) Hernández-Almada, A.; García-Aspeitia, Miguel A.; Rodríguez-Meza, M. A.; Motta, V.Motivated by two seminal models proposed to explain the Universe acceleration, this paper is devoted to study a hybrid model which is constructed through a generalized Chaplygin gas with the addition of a bulk viscosity. We call the model a viscous generalized Chaplygin gas (VGCG) and its free parameters are constrained through several cosmological data like the Observational Hubble Parameter, Type Ia Supernovae, Baryon Acoustic Oscillations, Strong Lensing Systems, HII Galaxies and using Joint Bayesian analysis. In addition, we implement a Om-diagnostic to analyze the VGCC dynamics and its difference with the standard cosmological model. The hybrid model shows important differences when compared with the standard cosmological model. Finally, based on our Joint analysis we find that the VGCG could be an interesting candidate to alleviate the well-known Hubble constant tension.Ítem Barrow Entropy Cosmology: an observational approach with a hint of stability analysis(Iop Press, 2021) Leon, Genly; Magaña, Juan; Hernández-Almada, A.; García-Aspeitia, Miguel A.; Verdugo, Tomás; Motta, V.In this work, we use an observational approach and dynamical system analysis to study the cosmological model recently proposed by Saridakis (2020), which is based on the modification of the entropy-area black hole relation proposed by Barrow (2020). The Friedmann equations governing the dynamics of the Universe under this entropy modification can be calculated through the gravity-thermodynamics conjecture. We investigate two models, one considering only a matter component and the other including matter and radiation, which have new terms compared to the standard model sourcing the late cosmic acceleration. A Bayesian analysis is performed in which using five cosmological observations (observational Hubble data, type Ia supernovae, HII galaxies, strong lensing systems, and baryon acoustic oscillations) to constrain the free parameters of both models. From a joint analysis, we obtain constraints that are consistent with the standard cosmological paradigm within 2σ confidence level. In addition, a complementary dynamical system analysis using local and global variables is developed which allows obtaining a qualitative description of the cosmology. As expected, we found that the dynamical equations have a de Sitter solution at late times.Ítem Erratum: Is every strong lens model unhappy in its own way? Uniform modelling of a sample of 13 quadruply+ imaged quasars(Royal Astronomical Society, 2021) Shajib, A. J.; Birrer, S.; Treu, T.; Auger, M. W.; Agnello, A.; Anguita, T.; Buckley-Geer, E. J.; Chan, J. H. H.; Collett, T. E.; Courbin, F.; Fassnacht, C. D.; Frieman, J.; Kayo, I.; Lemon, C.; Lin, H.; Marshall, P. J.; Mcmahon, R.; More, A.; Morgan, N. D.; Motta, V.; Oguri, M.; Ostrovski, F.; Rusu, C. E.; Schechter, P. L.; Shanks, T.; Suyu, S. H.; Meylan, G.; Abbott, T. M. C.; Allam, S.; Annis, J.; Avila, S.; Bertin, E.; Brooks, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cunha, V; Da Costa, L. N.; De Vicente, J.; Desai, S.; Doel, P.; Flaugher, B.; Fosalba, P.; Garcia-Bellido, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hartley, W. G.; Hollowood, D. L.; Hoyle, B.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.The paper ‘Is every strong lens model unhappy in its own way? Uniform modelling of a sample of 13 quadruply+ imaged quasars’ was published in MNRAS, 483, 4, 5649–5671 (2019). The coordinate values of the image positions in table 4 were wrongly printed due to a clerical error. At a later stage of writing the manuscript, we have changed the zero-point definition of the lens coordinate systems, but the relative image positions were not accounted for this change of definition while printing out table 4. We provide the updated Table 4 below. This error does not impact any other results of the paper in any way, except for the table itself. We thank Collin Werner and Paul Schechter for helping us identify this error.Ítem First black hole mass estimation for the quadruple lensed system WGD2038-4008(European Southern Observatory (ESO), 2021) Melo, A.; Motta, V.; Godoy, N.; Mejia-Restrepo, J.; Assef, R. J.; Mediavilla, E.; Falco, E.; Ávila-Vera, F.; Jerez, R.Context. The quadruple lensed system WGD2038-4008 (zs = 0.777 ± 0.001) has recently been discovered with the help of new techniques and observations. Black hole masses have been estimated for lensed quasars, but they have mostly been calculated for one broad emission line of one image. However, the images could be affected by microlensing, which changes the results. Aims. We present black hole mass (MBH) estimations for images A and B of WGD2038-4008 using the three most prominent broad emission lines (Hα, Hβ, and Mg II) obtained in one single-epoch spectra. This is the first time the mass has been estimated in a lensed quasar in two images, allowing us to disentangle the effects of microlensing. The high S/N of our spectra allows us to get reliable results that can be compared with the existing data in the literature. Methods. We used the X-shooter instrument mounted on the Very Large Telescope at Paranal Observatory to observe this system, taking advantage of its wide spectral range (UVB, VIS, and NIR). The sky emission correction was performed using principal component analysis as the nodding was small compared to the image separation. We compared the lines profiles to identify the microlensing in the broad-line region and corrected each spectra by the image magification. Using the flux ratio of the continuum to the core of the emission lines, we analyzed whether microlensing was present in the continuum source. Results. We obtained MBH using the single-epoch method with the Hα and Hβ emission lines from the monochromatic luminosity and the velocity width. The luminosity at 3000 Å was obtained using the spectral energy distribution of image A, while the luminosity at 5100 Å was estimated directly from the spectra. The average MBH between the images obtained was log10(MBH/M⊙) = 8.27 ± 1.05, 8.25 ± 0.32, and 8.59 ± 0.35 for Mg II, Hβ, and Hα, respectively. We find Eddington ratios similar to those measured in the literature for unlensed low-luminosity quasars. Microlensing of −0.16 ± 0.06 mag in the continuum was found, but the induced error in the MBH is minor compared to that associated with the macromodel magnification. We also obtained the accretion disk size using the MBH for the three emission lines, obtaining an average value of log10(rs/cm)=15.3 ± 0.63, which is in agreement with theoretical estimates.Ítem Linear perturbations spectra for dynamical dark energy inspired by modified gravity(World Scientific Publishing, 2021) Escamilla-Rivera, Celia; Hernández-Almada, A.; García-Aspeitia, Miguel A.; Motta, V.In this paper, we study a particular modified gravity Equation of State (EoS), the so-called Jaime–Jaber–Escamilla, that emerges from the first gravity modified action principle and can reproduce three cosmological viable f(R) theories: the Starobinsky, Hu–Sawicki and Exponential models. This EoS is a suitable candidate to reproduce the dynamical dark energy behaviour already reconstructed by the current data sets. Based on the joint statistical analysis, we found that our results are still in good agreement (within 1σ) with the ΛCDM, while at perturbative level, we note that the matter power spectrum normalisation factor σ8 shows an agreement with SDSS and SNeIa+IRAS at 1-σ for the Starobinsky model and with SDSS-vec for the Hu–Sawicki and Exponential models. Furthermore, we found that for the H0 values, Starobinsky and Hu–Sawicki show the least tension in comparison with PL18 TT. All these aspects cannot be observed directly from other alternatives theories, where an equation of state is difficult to compute analytically.Ítem Microlensing of the broad emission lines in 27 gravitationally lensed quasars Broad line region structure and kinematics(European Southern Observatory (ESO), 2021) Fian, C.; Mediavilla, E.; Motta, V.; Jiménez-Vicente, J.; Muñoz, J. A.; Chelouche, D.; Hanslmeier, A.Aims. We aim to study the structure and kinematics of the broad line region (BLR) of a sample of 27 gravitationally lensed quasars with up to five different epochs of observation. This sample is composed of ∼100 spectra from the literature plus 22 unpublished spectra of 11 systems. Methods. We measure the magnitude differences in the broad emission line (BEL) wings and statistically model the distribution of microlensing magnifications to determine a maximum likelihood estimate for the sizes of the C IV, C III], and Mg II emitting regions. Results. The BELs in lensed quasars are expected to be magnified differently owing to the different sizes of the regions from which they originate. Focusing on the most common BELs in our spectra (C IV, C III], and Mg II), we find that the low-ionization line Mg II is only weakly affected by microlensing. In contrast, the high-ionization line C IV shows strong microlensing in some cases, indicating that its emission region is more compact. Thus, the BEL profiles are deformed differently depending on the geometry and kinematics of the corresponding emitting region. We detect microlensing in either the blue or the red wing (or in both wings with different amplitudes) of C IV in more than 50% of the systems and find outstanding asymmetries in the wings of QSO 0957+561, SDSS J1004+4112, SDSS J1206+4332, and SDSS J1339+1310. This observation indicates that the BLR is, in general, not spherically symmetric and supports the existence of two regions in the BLR, one insensitive to microlensing and another that only shows up when it is magnified by microlensing. Disregarding the existence of these two regions, our estimate for Mg II, R1/2 = 67.3−15.7+3.8 √(M/M⊙) light-days, is in good agreement with previous results from smaller samples, while we obtain smaller sizes for the C III] and CIV lines, R1/2 = 31.0−4.0+1.9 √(M/M⊙) light-days and R1/2 = 15.5−3.9+0.8 √(M/M⊙) light-days, respectively.Ítem Revealing the structure of the lensed quasar Q 0957+561 I. Accretion disk size(European Southern Observatory (ESO), 2021) Fian, C.; Mediavilla, E.; Jiménez-Vicente, J.; Motta, V.; Muñoz, J. A.; Chelouche, D.; Goméz-Alvarez, P.; Rojas, K.; Hanslmeier, A.Aims. We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally lensed quasar Q 0957+561. The long-term photometric monitoring of this system (which so far has provided the longest available light curves of a gravitational lens system) permits us to evaluate the impact of uncertainties on our recently developed method (controlled by the distance between the modeled and the experimental magnitude difference histograms between two lensed images), and thus to test the robustness of microlensing-based disk-size estimates. Methods. We analyzed the well-sampled 21-year GLENDAMA optical light curves of the double-lensed quasar and studied the intrinsic and extrinsic continuum variations. Using accurate measurements for the time delay between the images A and B, we modeled and removed the intrinsic quasar variability, and from the statistics of microlensing magnifications we used a Bayesian method to derive the size of the region emitting the continuum at λrest = 2558 Å. Results. Analysis of the Q 0957+561 R-band light curves show a slow but systematic increase in the brightness of the B relative to the A component during the past ten years. The relatively low strength of the magnitude differences between the images indicates that the quasar has an unusually big optical accretion disk of half-light radius: R1/2 = 17.6±6.1 √(M/0.3 M⊙) lt-days.Ítem The Universe acceleration from the Unimodular gravity view point: Background and linear perturbations(Elsevier, 2021) García-Aspeitia, Miguel A.; Hernández-Almada, A.; Magaña, Juan; Motta, V.With the goal of studying the cosmological constant (CC) problem, we present an exhaustive analysis of unimodular gravity as a possible candidate to resolve the CC origin and with this, the current Universe acceleration. In this theory, a correction constant (CC-like) in the field equations sources the late cosmic acceleration. This constant is related to a new parameter, , which is interpreted as the redshift of CC-like emergence. By comparing with the CC value obtained from Planck and Supernovaes measurements, it is possible to estimate and respectively, which is close to the reionization epoch. Moreover, we use the observational Hubble data (OHD), Type Ia Supernovae (SnIa), Baryon Acoustic Oscillations (BAO) and the Cosmic Microwave Background Radiation (CMB) distance data to constrain the UG cosmological parameters. A Joint analysis (OHD+SnIa+BAO+CMB), results in within confidence level consistent with our estimation from Planck and Supernovae measurements. We also include linear perturbations, starting with scalar and tensor perturbations and complementing with the perturbed Boltzmann equation for photons. We show that the 00 term in the UG field equations and the Boltzmann equation for photons contains corrections, meanwhile the other equations are similar as those obtained in standard cosmology.