arXiv subjects

Gustavo F. Gonçalves

Publications and source records attributed to Gustavo F. Gonçalves.

4 recordsLinked to original sources

arXiv2026

SAMI and TNG-Cluster: tracing galaxy spin and environmental transformation across cluster phase-space and cosmic time

The dense environment of galaxy clusters suppresses star formation and alters the kinematic properties of infalling satellites through gas stripping, tidal interactions, gravitational harassment and starvation. Projected phase-space diagrams connect the present-day distribution of cluster galaxies to their accretion histories. We combine SAMI Galaxy Survey integral field spectroscopy with the TNG-Cluster simulation to investigate how the stellar spin parameter ($λ_R$), $(g-i)$ colour, and sSFR vary across projected phase-space infall regions. At $z = 0$, TNG-Cluster reproduces the direction and broad strength of the phase-space trends observed in SAMI, including the weak yet significant $λ_R$-clustercentric distance correlation. Leveraging this agreement, we extend the analysis across the last 8 Gyr, tracing the statistical evolution of galaxy properties within each infall region, and complement this with individual orbital histories of representative satellites. While colour and sSFR show clear monotonic gradients with both phase-space position and cosmic time, $λ_R$ behaves differently: it remains largely uniform across the outer infall regions, with only the virialised core exhibiting systematically lower values, and displays a slow monotonic decline toward the present day across all regions. We find that angular momentum suppression driven by the cluster environment is a slow, cumulative process requiring several Gyr of exposure to the cluster core, modulated by orbital history and stellar mass. This gradual nature explains why the $λ_R$-environment correlation appears weak across phase-space regions in statistical samples; the effect emerges when individual satellite histories are tracked, revealing a sustained dynamical response to prolonged cluster residence.

astro-ph.GA↗

arXiv2026

The detectability of bars at high redshift: a case study using Euclid-like mock observations of TNG50 simulated galaxies

Modern surveys such as Euclid report a decline in the fraction of barred galaxies from the local Universe to $z \sim 1$, whereas the TNG50 simulation predicts higher bar fractions, in tension with observations. This discrepancy may be due to observational biases in bar detectability when comparing simulations with observations. We present a proof-of-concept study quantifying how Euclid-like observational conditions affect bar detectability in TNG50. We analysed the entire galaxy sample at $z = 0.5$ and highlight one borderline case with a bar length of 2.1 kpc and bar strength $A_2 = 0.4$. Synthetic images were produced with Monte Carlo radiative transfer and realistic post-processing, and analysed with ellipse fitting and Fourier decomposition, as well as the recently constructed Zoobot analysis. Results were compared to idealised, noise-free stellar mass maps. In the illustrative case the bar is clearly detected in the mass map and remains visible in the Euclid VIS $I_{\rm E}$ filter, where Zoobot also classifies it as barred, but becomes undetectable in $Y_{\rm E}$ and in the VIS-NISP RGB composite, with all methods failing outside VIS. Extending to the full $z = 0.5$ sample, Zoobot recovers only 31/141 galaxies, while $A_2$ and ellipse fitting perform better (80/141 and 67/141) but still miss many short or weak bars. When non-detections are counted as unbarred, the bar fraction of 44 percent falls to $12\!-\!33$ percent depending on the method. These results demonstrate the strong impact of observational effects on bar detectability and motivate bar-fraction estimates which incorporate realistic instrumental conditions across redshift in cosmological simulations.

astro-ph.GA↗

arXiv2025

Bar properties as a function of wavelength in TNG50: analysis of mock images

Recent studies used TNG50 galaxies to study bar formation, evolution, and properties like length, strength, and pattern speed. In simulations, these are typically derived from particle positions and mass distribution, neglecting stellar light and extinction effects. However, observational studies indicate that bar appearance depends on wavelength. To test whether this dependence exists in TNG50 at $z \sim 0$, we analysed 50 strongly barred galaxies using mock images from SKIRT radiative transfer simulations covering infrared to ultraviolet filters (Spitzer 3.6 um, SDSS i, r, g, S-PLUS J0378, GALEX NUV, and GALEX FUV). Bar ellipticity and length were measured via ellipse fitting. Ellipticity generally increases by 6 percent from 3.6 um to g band, and by 9 percent to J0378 band. On average, TNG50 bars cannot be said to be longer in bluer filters when the entire sample is used. However, the trend is detected when only star-forming galaxies are considered. In this star-forming subsample, bar length increases by 10 percent from 3.6 um to g band, and by 17 percent to J0378 band; moreover, the bar can appear up to 20${-}$30 percent longer in bluer mocks than in the mass map. Over 90 percent of bars vanish in UV due to minimal emission by dominant stellar populations. We reproduced the bar properties morphological dependence phenomenon using age-filtered mass maps, where older stars form shorter, rounder bars, and younger stars generate longer, more elliptical ones. TNG50 bars exhibit a wavelength-dependent trend similar to observations: bars appear more elliptical and longer in bluer filters, with this effect being stronger in star-forming galaxies.

astro-ph.GA↗

arXiv2024

The rotation of classical bulges in barred galaxies in the presence of gas

Barred galaxies often develop a box/peanut pseudobulge, but they can also host a nearly spherical classical bulge, which is known to gain rotation due to the bar. We aim to explore how the presence of gas impacts the rotation of classical bulges. We carried out a comprehensive set of hydrodynamical N-body simulations with different combinations of bulge masses and gas fractions. In these models, both massive bulges and high gas content tend to inhibit the formation of strong bars. For low-mass bulges, the resulting bar is stronger in cases of low gas content. In the stronger bar models, bulges acquire more angular momentum and thus display considerable rotational velocity. Such bulges also develop anisotropic velocity dispersions and become triaxial in shape. We found that the rotation of the bulge becomes less pronounced as the gas fraction is increased from 0 to 30%. These results indicate that the gas content has a significant effect on the dynamics of the classical bulge, because it influences bar strength. Particularly in the case of the low-mass bulges (10% bulge mass fraction), all of the measured rotational and structural properties of the classical bulge depend strongly and systematically on the gas content of the galaxy.

astro-ph.GA↗