arXiv subjects

Rosa Dominguez-Tenreiro

Publications and source records attributed to Rosa Dominguez-Tenreiro.

11 recordsLinked to original sources

arXiv2026

The properties of central stellar knots embedded in galactic bulges of CIELO simulations

Deeply bound stellar substructures of about 1 kpc at the center of bulges are found in a subset of galaxies from the cosmological chemo-hydrodynamical zoom-in CIELO simulation suite. They were identified as stellar overdensities at the lowest binding energies in each galaxy's circularity-energy $(ε, E)$ plane. We refer to these overdensities as stellar knots. We aim to characterize their properties in the context of bulge assembly using CIELO simulated galaxies spanning a wide range of stellar masses ($10^{8.0}$-$10^{10.7}\,\mathrm{M}_{\odot}$), with diverse formation histories. We inspect 54 galactic bulges. Within them, we isolate stellar knot candidates in $(ε, E)$ space, and identify 28 robust knots satisfying successive selection criteria: kinematic, concentration, and morphology. We characterize their chemical enrichment, formation timescales, formation sites, progenitor gas origin, and spatial distributions. Across all galaxy masses, knots are systematically alpha-element enhanced, having assembled the bulk of their stellar mass at earlier epochs and on shorter timescales than other bulge populations, with a median of $\sim$2$\,$Gyr versus $\sim$5$\,$Gyr. Regarding their origin, knots are predominantly in-situ ($5\%$ accreted mass fraction, roughly half that of the rest of the bulge), with negligible disk-born stars contribution and the largest gas fractions originating from a primordial central spheroid ($21\%$ versus 16--17$\%$ for the surrounding populations), consistent with being the primary gas fuel for the alpha-element enhancement. In terms of structure, knots exhibit a variety of morphologies, with spheroidal shapes predominating. Dynamical selection in $(ε, E)$ space of CIELO galaxies demonstrates its effectiveness in recovering coeval stellar populations, pointing to stellar knots as plausible fossil signatures of early in-situ bulge assembly.

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arXiv2026

The heartbeat of stellar halos: Insights from the stellar halo mass-metallicity relation

This work investigates the presence and evolution of the MZhR from redshift z=3.5 to z=0, and identifies when galaxies settle on the present-day MZhR. We used central galaxies with log10(Mgal/Msun)=[9,11] from CIELO simulations. We identified stellar halos, from z=3.5 to z=0, using the AM-E method, focusing on the region between the 1.5 optical radius and the virial radius. We presented halo cardiograms, a novel approach to studying the assembly history of stellar halos. Using them, we defined a stability time (tst) as the first time that the median halo metallicity does not change more than \pm 0.1 dex with respect to its value at z=0. CIELO stellar halos reproduce the present-day observed MZhR. At z=3.5, stellar halos already define an MZhR whose slope is similar to the slope at z=0. For a fixed stellar halo mass, the metallicity increases ~0.21 dex from z=3.5 to z=0, reflecting the progressive chemical enrichment provided by the accretion of satellites with diverse masses and different levels of enrichment. When the first stellar halo main contributor (SHMC1) provides a mass fraction at least 20% higher than the remaining contributors, the stellar halo metallicity is set once SHMC1 is fully disrupted (tmerger). This yields a clear correlation between tst and tmerger, with a scatter of 2.2 Gyr driven by the relative importance of the second and third main contributing satellites. We provide two observational tracers for tst: t90 and a stability time from the age-metallicity relation. Our results suggest that estimating tst could serve as a proxy for dating the moment at which the stellar halo reaches the present-day MZhR, as well as for dating the last major merger that builds them. Combined with an estimation of the merger time of the main contributing satellite, it can provide insights into the relative importance of the second and third contributing satellites. (abridged)

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arXiv2025

The CIELO Project: The Chemo-dynamical properties of gaLaxies and the cosmic web

The CIELO project introduces a novel set of chemo-dynamical zoom-in simulations designed to simultaneously resolve galaxies and their nearby environments. The initial conditions include a diverse range of cosmic structures, such as local groups, filaments, voids, and walls, allowing for a detailed exploration of galaxies within the broader context of the cosmic web. This study presents the initial conditions and characterizes the global properties of CIELO galaxies and their environments. It focuses on galaxies with stellar masses ranging from log [8,11] solar masses and examines key scaling relations, including the mass-size relation, the Tully-Fisher relation, and the mass-metallicity relation for both stars and star-forming gas. The DisPerSe algorithm was used to determine the positions of CIELO galaxies within the cosmic web, with a specific focus on the Pehuen haloes. The selection of local group volumes was guided by criteria based on the relative positions and velocities of the two primary galaxies. The Pehuen regions were chosen to map walls, filaments, and voids. Synthetic images in the SDSS i, r, and g bands were generated using the SKIRT radiative transfer code. Additionally, a dynamical decomposition was performed to classify galaxy morphologies into bulge, disc, and stellar halo components (abridged).

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arXiv2023

Redshift evolution of the dark matter haloes shapes

In this work, we aim at investigating the morphology evolution of Milky Way mass-like dark matter haloes selected from the CIELO and IllustrisTNG Projects. The connection between halo shapes and their environment has been studied in previous works at z=0 but their connection remains yet to be fully understood. We focus on the evolution across cosmic time of the halo shapes and the relation with the infalling material, using hydrodynamical simulations. Our findings show that haloes tend to be more triaxial at earlier times as a consequence of stronger accretion in the direction of the filaments. As the haloes evolve towards a dominant isotropic accretion mode and relaxation, their shape at 20 percent of the virial mass becomes more spherical. In agreement with previous results, baryons have an important effect within the inner regions of the haloes, driving them from triaxial to rounder shapes. We also find a correlation between the strength of the quadrupole infalling mode and the degree of ellipticity of the haloes: as the filament strength decreases steadily with redshift, the haloes became more spherical and less elliptical.

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arXiv2022

Milky Way-like galaxies: stellar population properties of dynamically defined disks, bulges and stellar halos

The formation of galaxies can be understood in terms of the assembly patterns of each type of galactic component. To perform this kind of analysis, is necessary to define some criteria to separate those components. Decomposition methods based on dynamical properties are more physically motivated than photometry-based ones. We use the unsupervised Gaussian Mixture model of \texttt{galactic structure finder} to extract the components of a sub-sample of galaxies with Milky Way-like masses from the EAGLE simulations. A clustering in the space of first and second order dynamical moments of all identified substructures reveals five types of galaxy components: thin and thick disks, stellar halos, bulges and spheroids. We analyse the dynamical, morphological and stellar population properties of these five component types, exploring to what extent these properties correlate with each other, and how much they depend on the total galaxy stellar and dark matter halo masses. All galaxies contain a bulge, a stellar halo and a disk. 60% of objects host two disks (thin and thick), and 68% host also a spheroid. The dynamical disk-to-total ratio does not depend on stellar mass, but the median rotational velocities of the two disks do. Thin disks are well separated in stellar ages, [Fe/H] and $α$-enhancement from the three dispersion-dominated components, while thick disks are in between. Except for thin disks, all components show correlations among their stellar population properties: older ages mean lower metallicities and larger $α$-enhancement. Finally, we quantify the weak dependence of stellar population properties on each component's dynamics.

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arXiv2020

An updated detailed characterization of planes of satellites in the MW and M31

We present a detailed characterization of planes of satellite galaxies in the Milky Way (MW) and M31. For a positional analysis, we introduce an extension to the `4-galaxy-normal density plot' method \citep[][P13]{Pawlowski13}. It finds the normal directions to the predominant planar configurations of satellites of a system, yielding for each a \textit{collection} of planes of increasing member satellites. This allows to quantify the quality of planes in terms of population ($N_{\rm sat}$) and spatial flattening ($c/a$). We apply this method to the latest data for confirmed MW and M31 satellite samples, with 46 and 34 satellites, respectively. New MW satellites form part of planes previously identified from the sample with $N_{\rm sat}=27$ studied in P13: we identify a new plane with $N_{\rm sat}=39$ as thin as the VPOS-3 ($c/a\sim 0.2$), and with roughly the same normal direction; so far the most populated plane that thin reported in the Local Group. We introduce a new method to determine, using kinematic data, the axis of maximum co-orbitation of MW satellites. Interestingly, this axis approximately coincides with the normal to the former plane: $\geq45\pm5\%$ of satellites co-orbit. In M31 we discover a plane with $N_{\rm sat}=18$ and $c/a\sim0.15$, i.e., quality comparable to the GPoA, and perpendicular to it. This structure is viewed face-on from the Sun making it susceptible to M31 satellite distance uncertainties. An estimation of the perpendicular velocity dispersion suggests it is dynamically unstable. Finally we find that mass is not a property determining a satellite's membership to good quality planes.

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arXiv2020

Planes of satellites around simulated disc galaxies: I.- Finding high-quality planar configurations from positional information and their comparison to MW/M31 data

We address the 'plane of satellites problem' by studying planar configurations around two disc galaxies with no late major mergers, formed in zoom-in hydro-simulations. Due to the current lack of good quality kinematic data for M31 satellites, we use only positional information. So far, positional analyses of simulations are unable to find planes as thin and populated as the observed ones. Moreover, they miss systematicity and detail in the plane-searching techniques, as well as in the study of the properties and quality of planes, both in simulations or real data. To fill this gap, i) we extend the 4-galaxy-normal density plot method (Pawlowski et al. 2013) in a way designed to efficiently identify the best quality planes (i.e., thin and populated) without imposing extra constraints on their properties, and ii), we apply it for the first time to simulations. Using zoom-in simulations allows us to mimic MW/M31-like systems regarding the number of satellites involved as well as the galactic disc mass and morphology, in view of possible disc effects. At all timesteps analyzed in both simulations we find satellite planar configurations that are compatible, along given time intervals, with all the spatial characteristics of observed planes identified using the same methodology. However, the fraction of co-orbiting satellites within them is in general low, suggesting time-varying satellite membership. We conclude that high-quality positional planes of satellites are not infrequent in LCDM-formed disc galaxies with a quiet assembly history. Detecting kinematically-coherent, time-persistent planes demands considering the full six-dimensional phase-space information of satellites.

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arXiv2015

The early phases of galaxy clusters formation in IR: coupling hydrodynamical simulations with GRASIL3D

We compute and study the infrared and sub-mm properties of high redshift ($z \gtrsim 1$) simulated clusters and proto-clusters. The results of a large set of hydro-dynamical zoom-in simulations including active galactic nuclei (AGN) feedback, have been treated with the recently developed radiative transfer code GRASIL-3D, which accounts for the effect of dust reprocessing in an arbitrary geometry. Here, we have slightly generalized the code to adapt it to the present purpose. Then we have post-processed boxes of physical size 2 Mpc encompassing each of the 24 most massive clusters identified at z=0, at several redshifts between 0.5 and 3, producing IR and sub-mm mock images of these regions and SEDs of the radiation coming out from them. While this field is in its infancy from the observational point of view, rapid development is expected in the near future thanks to observations performed in the far IR and sub-mm bands. Notably, we find that in this spectral regime our prediction are little affected by the assumption required by this post-processing, and the emission is mostly powered by star formation rather than accretion onto super massive black hole (SMBH). The comparison with the little observational information currently available, highlights that the simulated cluster regions never attain the impressive star formation rates suggested by these observations. This problem becomes more intriguing taking into account that the brightest cluster galaxies (BCGs) in the same simulations turn out to be too massive. It seems that the interplay between the feedback schemes and the star formation model should be revised, possibly incorporating a positive feedback mode.

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arXiv2013

Galaxies going MAD: The Galaxy-Finder Comparison Project

With the ever increasing size and complexity of fully self-consistent simulations of galaxy formation within the framework of the cosmic web, the demands upon object finders for these simulations has simultaneously grown. To this extent we initiated the Halo Finder Comparison Project that gathered together all the experts in the field and has so far led to two comparison papers, one for dark matter field haloes (Knebe et al. 2011), and one for dark matter subhaloes (Onions et al. 2012). However, as state-of-the-art simulation codes are perfectly capable of not only following the formation and evolution of dark matter but also account for baryonic physics (e.g. hydrodynamics, star formation, feedback) object finders should also be capable of taking these additional processes into consideration. Here we report on a comparison of codes as applied to the Constrained Local UniversE Simulation (CLUES) of the formation of the Local Group which incorporates much of the physics relevant for galaxy formation. We compare both the properties of the three main galaxies in the simulation (representing the MW, M31, and M33) as well as their satellite populations for a variety of halo finders ranging from phase-space to velocity-space to spherical overdensity based codes, including also a mere baryonic object finder. We obtain agreement amongst codes comparable to (if not better than) our previous comparisons, at least for the total, dark, and stellar components of the objects. However, the diffuse gas content of the haloes shows great disparity, especially for low-mass satellite galaxies. This is primarily due to differences in the treatment of the thermal energy during the unbinding procedure. We acknowledge that the handling of gas in halo finders is something that needs to be dealt with carefully, and the precise treatment may depend sensitively upon the scientific problem being studied.

astro-ph.CO↗

arXiv2013

Structure Finding in Cosmological Simulations: The State of Affairs

The ever increasing size and complexity of data coming from simulations of cosmic structure formation demands equally sophisticated tools for their analysis. During the past decade, the art of object finding in these simulations has hence developed into an important discipline itself. A multitude of codes based upon a huge variety of methods and techniques have been spawned yet the question remained as to whether or not they will provide the same (physical) information about the structures of interest. Here we summarize and extent previous work of the "halo finder comparison project": we investigate in detail the (possible) origin of any deviations across finders. To this extent we decipher and discuss differences in halo finding methods, clearly separating them from the disparity in definitions of halo properties. We observe that different codes not only find different numbers of objects leading to a scatter of up to 20 per cent in the halo mass and Vmax function, but also that the particulars of those objects that are identified by all finders differ. The strength of the variation, however, depends on the property studied, e.g. the scatter in position, bulk velocity, mass, and the peak value of the rotation curve is practically below a few per cent, whereas derived quantities such as spin and shape show larger deviations. Our study indicates that the prime contribution to differences in halo properties across codes stems from the distinct particle collection methods and -- to a minor extent -- the particular aspects of how the procedure for removing unbound particles is implemented. We close with a discussion of the relevance and implications of the scatter across different codes for other fields such as semi-analytical galaxy formation models, gravitational lensing, and observables in general.

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arXiv2006

Hydrodynamic Approach to the Evolution of Cosmic Structures II: Study of N-body Simulations at z=0

We present a series of cosmological N-body simulations which make use of the hydrodynamic approach to the evolution of structures (Dominguez 2000). This approach addresses explicitly the existence of a finite spatial resolution and the dynamical effect of subresolution degrees of freedom. We adapt this method to cosmological simulations of the standard LCDM structure formation scenario and study the effects induced at redshift z=0 by this novel approach on the large-scale clustering patterns as well as (individual) dark matter halos. Comparing these simulations to usual N-body simulations, we find that (i) the new (hydrodynamic) model entails a proliferation of low--mass halos, and (ii) dark matter halos have a higher degree of rotational support. These results agree with the theoretical expectation about the qualitative behaviour of the "correction terms" introduced by the hydrodynamic approach: these terms act as a drain of inflow kinetic energy and a source of vorticity by the small-scale tidal torques and shear stresses.

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