Browsing by Author "Barrientos Parra, Luis Felipe"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A compact group lens modeled with GIGA-Lens: Enhanced inference for complex systems
    (EDP SCIENCES S A, 2025) Urcelay Solis De Ovando, Felipe José; Jullo, Eric; Barrientos Parra, Luis Felipe; Huang, Xiaosheng; Hernández Guajardo, Joaquín Alexis
    Context. In the era of large-scale astronomical surveys, the fast modeling of strong lens systems has become increasingly vital. While significant progress has been made for galaxy-scale lenses, the development of automated methods for modeling larger systems, such as groups and clusters, is not as extensive., Aims. Our study aims to extend the capabilities of the GIGA-Lens code, enhancing its efficiency in modeling multi-galaxy strong lens systems. We focus on demonstrating the potential of GPU-accelerated Bayesian inference in handling complex lensing scenarios with a high number of free parameters., Methods. We employed an improved inference approach that combines image position and pixelated data with an annealing sampling technique to obtain the posterior distribution of complex models. This method allowed us to overcome the challenges of limited prior information, a high number of parameters, and memory usage. We validated our process through the analysis of the compact group lens system DES J0248-3955 and we present the relevant VLT/X-shooter spectra., Results. We measured a redshift of z = 0.69 +/- 0.04 for the group, and z = 1.2722 +/- 0.0005 for one of the extended arcs. Our enhanced method successfully constrained a lens model with 29 free parameters and lax priors in a remarkably short time. The mass of the lens is well described by a single dark-matter halo with a velocity dispersion of sigma(v) = (690 +/- 30) km s(-1). The model predicts the presence of a second source at the same redshift and a third source at approximately z similar to 2.7., Conclusions. Our study demonstrates the effectiveness of our lens modeling technique for dealing with a complex system in a short time using ground-based data. This presents a considerable prospect within the context of large surveys, such as LSST, in the future.
  • Thumbnail Image
    Item
    A resolved Lyman α profile with doubly peaked emission at z∼7
    (EDP Sciences, 2024) Moya Sierralta, Cristobal; González López, Jorge; Infante Lira Leopoldo; Barrientos Parra, Luis Felipe; Hu, W.; Malhotra, S.; Rhoads, J.; Wang, J.; Wold, I.; Zheng, Z.
    © The Authors 2024.Context. The epoch of reionization is a landmark in structure formation and galaxy evolution. How it happened is still not clear, especially regarding which population of objects was responsible for contributing the bulk of ionizing photons to this process. Doubly peaked Lyman-alpha profiles in this epoch are of particular interest since they hold information about the escape of ionizing radiation and the environment surrounding the source. Aims. We wish to understand the escape mechanisms of ionizing radiation in Lyα emitters during this time and the origin of a doubly peaked Lyman-alpha profile. We also wish to estimate the size of a potential ionized bubble. Methods. Using radiative transfer models, we fit the line profile of a bright Lyα emitter at z-≈-6.9 using various gas geometries. The line modeling reveals significant radiation escape from this system. Results. The studied source shows significant escape (fesc(Lyα) ≈ 0.8, as predicted by the best fitting radiative transfer model) and appears to inhabit an ionized bubble of radius Rb-0.8-0.3+0.5-pMpc(tage/108)1/3. Radiative transfer modeling predicts the line to be completely redward of the systemic redshift. We suggest the line morphology is produced by inflows, by multiple components emitting Lyα, or by an absorbing component in the red wing. Conclusions. We propose that CDFS-1-s profile has two red peaks produced by winds within the system. Its high fesc(Lyα) and the low-velocity offset from the systemic redshift suggest that the source is an active ionizing agent. Future observations will reveal whether a peak is present blueward of the systemic redshift or if multiple components produce the profile.
  • Thumbnail Image
    Item
    Directly constraining the spatial coherence of the z ∼ 1 circumgalactic medium
    (2023) Afruni, A.; Lopez, S.; Anshul, P.; Tejos, N.; Noterdaeme, P.; Berg, T. A. M.; Ledoux, C.; Solimano, M.; Gonzalez-Lopez, J.; Gronke, M.; Barrientos Parra, Luis Felipe; Johnston, E. J.
    One of the biggest puzzles regarding the circumgalactic medium (CGM) is the structure of its cool (T ∼ 104 K) gas phase. While the kinematics of quasar absorption systems suggests the CGM is composed of a population of different clouds, constraining their extent and spatial distribution has proven challenging, both from theoretical and observational points of view. In this work, we study the spatial structure of the z ∼ 1 CGM with unprecedented detail via resolved spectroscopy of giant gravitational arcs. We put together a sample of Mg IIλλ2796, 2803 detections obtained with VLT/MUSE in 91 spatially independent and contiguous sight lines toward 3 arcs, each probing an isolated star-forming galaxy believed to be detected in absorption. We constrain the coherence scale of this gas (Clength) - which represents the spatial scale over which the Mg II equivalent width (EW) remains constant - by comparing EW variations measured across all sight lines with empirical models. We find 1.4 < Clength/kpc < 7.8 (95% confidence). This measurement, of unprecedented accuracy, represents the scale over which the cool gas tends to cluster in separate structures. We argue that, if Clength is a universal property of the CGM, it needs to be reproduced by current and future theoretical models in order for us to understand the exact role of this medium in galaxy evolution....