Santi Roca-Fàbrega

Santi Roca-Fàbrega
Universidad Nacional Autónoma de México | UNAM · Instituto de Astronomía de Ensenada

Doctor of Physics

About

47
Publications
1,770
Reads
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428
Citations
Citations since 2016
40 Research Items
396 Citations
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Skills and Expertise

Publications

Publications (47)
Preprint
Full-text available
Context: The high quality of the Gaia mission data is allowing to study the internal kinematics of the Large Magellanic Cloud (LMC) in unprecedented detail, providing insights on the non-axisymmetric structure of its disc. Aims: To define and validate an improved selection strategy to distinguish the LMC stars from the Milky Way foreground. To chec...
Preprint
A variety of new physical processes have proven to play an important role in orbital decay of a satellite galaxy embedded inside a dark matter halo but this is not fully understood. Our goal is to assess if the orbital history of a satellite remains unchanged during a concurrent sinking. For this purpose we analyze the impact that the internal stru...
Preprint
Full-text available
Most studies of highly ionized plasmas have historically assumed ions are either in photoionization equilibrium, PIE, or collisional ionization equilibrium, CIE, sometimes including multiple phases with different relevant mechanisms. Simulation analysis packages, on the other hand, tend to use precomputed ion fraction tables which include both mech...
Preprint
Context. Stellar tidal streams are the result of tidal interactions between a central galaxy and lower mass systems like satellite galaxies or globular clusters. For the Local Group, many diffuse substructures have been identified and their link to the galaxy evolution has been traced. However it cannot be assumed that the Milky Way or M31 are repr...
Preprint
Tidal ring galaxies are observed rarely in the local universe due to their intrinsically transient nature. The tidal ring structures are the result of strong interactions between gas-rich stellar disks and smaller galactic systems and do not last longer than ~500~Myr therefore, these are perfect scenarios where to find the debris of recently accret...
Preprint
We study the striking case of a blue narrow stream with a possible globular cluster-like progenitor around the Milky Way-size galaxy NGC 7241 and its foreground dwarf companion. We present a follow-up spectroscopic study of this stream based on data taken with the MEGARA instrument at the 10.4-m Gran Telescopio Canarias using the integral field spe...
Article
We study the vertical perturbations in the galactic disc of the Milky Way-size high-resolution hydrodynamical cosmological simulation named GARROTXA. We detect phase spirals in the vertical projection Z − VZ of disc’s stellar particles for the first time in this type of simulations. Qualitatively similar structures were detected in the recent Gaia...
Preprint
We study the vertical perturbations in the galactic disc of the Milky Way-size high-resolution hydrodynamical cosmological simulation named GARROTXA. We detect phase spirals in the vertical projection $Z- V_{Z}$ of disc's stellar particles for the first time in this type of simulations. Qualitatively similar structures were detected in the recent G...
Article
Context. The lithium abundance, A (Li), in stellar atmospheres suffers from various enhancement and depletion processes during the star’s lifetime. While several studies have demonstrated that these processes are linked to the physics of stellar formation and evolution, the role that Galactic-scale events play in the galactic A (Li) evolution is no...
Preprint
Full-text available
The lithium abundance, A(Li), in stellar atmospheres suffers from various enhancement and depletion processes during the star's lifetime. While several studies have demonstrated that these processes are linked to the physics of stellar formation and evolution, the role that Galactic-scale events play in the galactic A(Li) evolution is not yet well...
Article
We investigate two topics regarding solar mass FGK-type stars, the lithium-rotation connection (LRC), and the existence of the ‘lithium desert’. We determine the minimum critical rotation velocity ( v sin i ), related with the LRC separating slow from rapid stellar rotators, to be 5 km s ⁻¹ . This value also splits different stellar properties. For...
Preprint
Full-text available
We investigate two topics regarding solar mass FGK-type stars, the lithium rotation connection (LRC) and the existence of the "lithium desert". We determine the minimum critical rotation velocity ($v \sin i$) related with the LRC separating slow from rapid stellar rotators, as being 5 km s$^{-1}$. This value also split different stellar properties....
Presentation
Full-text available
This Keynote presentation gives an excellent overview of the AGORA paper III, i.e. the CosmoRun paper: arXiv:2106.09738.
Article
Full-text available
We present a suite of high-resolution cosmological zoom-in simulations to z = 4 of a 10¹² M_⊙ halo at z = 0, obtained using seven contemporary astrophysical simulation codes (Art-I, Enzo, Ramses, Changa, Gadget-3, Gear, and Gizmo) widely used in the numerical galaxy formation community. The physics prescriptions for gas cooling and heating and star...
Article
Recent evidence of extremely metal-rich stars found in the Sombrero galaxy (M104) halo suggests that this galaxy has undergone a recent major merger with a relatively massive galaxy. In this paper, we present wide-field deep images of the M104 outskirts obtained with a 18-cm amateur telescope with the purpose of detecting any coherent tidal feature...
Poster
Full-text available
AGORA is an acronym for Assembling Galaxies of Resolved Anatomy, and this project [J. Kim, et al. ApJ Supp., 210, 14 (2014) ] is approximately twelve years old and continuing strong. The CosmoRun paper is the third in this series and is a comparative set of zoom-in cosmological simulations of six codes using the same initial conditions (described i...
Preprint
Full-text available
We present a suite of high-resolution cosmological zoom-in simulations to $z=4$ of a $10^{12}\,{\rm M}_{\odot}$ halo at $z=0$, obtained using seven contemporary astrophysical simulation codes widely used in the numerical galaxy formation community. Physics prescriptions for gas cooling, heating, and star formation, are similar to the ones used in o...
Preprint
Recent evidence of extremely metal-rich stars found in the Sombrero galaxy (M104) halo suggests that this galaxy has undergone a recent major merger with a relatively massive galaxy. In this paper, we present wide-field deep images of the M104 outskirts obtained with a 18-cm amateur telescope with the purpose of detecting any coherent tidal feature...
Preprint
Mergers and tidal interactions between massive galaxies and their dwarf satellites are a fundamental prediction of the Lambda-Cold Dark Matter cosmology. These events are thought to provide important observational diagnostics of nonlinear structure formation. Stellar streams in the Milky Way and Andromeda are spectacular evidence for ongoing satell...
Article
We analyse the distribution and origin of OVI in the Circumgalactic Medium (CGM) of dark-matter haloes of ∼1012 M⊙ at z ∼ 1 in the VELA cosmological zoom-in simulations. We find that the OVI in the inflowing cold streams is primarily photoionized, while in the bulk volume it is primarily collisionally ionized. The photoionized component dominates t...
Preprint
Full-text available
We analyse the distribution and origin of OVI in the Circumgalactic Medium (CGM) of dark-matter haloes of $\sim 10^{12}$ M$_\odot$ at $z\sim1$ in the VELA cosmological zoom-in simulations. We find that the OVI in the inflowing cold streams is primarily photoionized, while in the bulk volume it is primarily collisionally ionized. The photoionized co...
Preprint
As part of the AGORA High-resolution Galaxy Simulations Comparison Project (Kim et al. 2014, 2016) we have generated a suite of isolated Milky Way-mass galaxy simulations using 9 state-of-the-art gravito-hydrodynamics codes widely used in the numerical galaxy formation community. In these simulations weadopted identical galactic disk initial condit...
Research
https://www.nature.com/articles/d41586-019-01226-2 This is a Nature Research Highlight based on the A&A letter: "Gaia DR2 reveals a star formation burst in the disc 2-3 Gyr ago" A&A 624, L1 (2019) https://doi.org/10.1051/0004-6361/201935105
Article
Full-text available
We use Gaia data release 2 (DR2) magnitudes, colours, and parallaxes for stars with G < 12 to explore a parameter space with 15 dimensions that simultaneously includes the initial mass function (IMF) and a non-parametric star formation history (SFH) for the Galactic disc. This inference is performed by combining the Besançon Galaxy Model fast appro...
Article
Full-text available
We study the components of cool and warm/hot gas in the circumgalactic medium (CGM) of simulated galaxies and address the relative production of OVI by photoionization versus collisional ionization, as a function of halo mass, redshift, and distance from the galaxy halo centre. This is done utilizing two different suites of zoom-in hydro-cosmologic...
Preprint
Full-text available
We study the components of cool and warm/hot gas in the circumgalactic medium (CGM) of simulated galaxies and address the relative production of OVI by photoionization versus collisional ionization, as a function of halo mass, redshift, and distance from the galaxy halo center. This is done utilizing two different suites of zoom-in hydro-cosmologic...
Conference Paper
Full-text available
MEGARA is the new generation IFU and MOS optical spectrograph built for the 10.4m Gran Telescopio CANARIAS (GTC). The project was developed by a consortium led by UCM (Spain) that also includes INAOE (Mexico), IAA-CSIC (Spain) and UPM (Spain). The instrument arrived to GTC on March 28 th 2017 and was successfully integrated and commissioned at the...
Article
Full-text available
We use the Gaia-TGAS data to compare the transverse velocities in Galactic longitude (coming from proper motions and parallaxes) in the Milky Way disk for negative and positive longitudes as a function of distance. The transverse velocities are strongly asymmetric and deviate significantly from the expectations for an axisymmetric Galaxy. The value...
Article
Using an isolated Milky Way-mass galaxy simulation, we compare results from 9 state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e...
Article
Full-text available
We introduce a new set of eight Milky Way-sized cosmological simulations performed using the AMR code ART + Hydrodynamics in a LCDM cosmology. The set of zoom-in simulations covers present-day virial masses in the 0.83-1.56 x 10^12 msun range and is carried out with our simple but effective deterministic star formation (SF) and ``explosive' stellar...
Article
Full-text available
We introduce a new set of simulations of Milky Way (MW)-sized galaxies using the AMR code ART + hydrodynamics in a Λ cold dark matter cosmogony. The simulation series is called GARROTXA and it follows the formation of a halo/galaxy from z = 60 to z = 0. The final virial mass of the system is ∼7.4 × 1011 M o. Our results are as follows. (a) Contrary...
Article
We model the effects of the spiral arms of the Milky Way on the disk stellar kinematics in the Gaia observable space. We also estimate the Gaia capabilities of detecting the predicted signatures. We use both controlled orbital integrations in analytic potentials and self-consistent simulations. We introduce a new strategy, which consists of compari...
Article
We present a new set of cosmological Milky Way size galaxy simulations using ART. In our simulations the main system has been evolved inside a 28 Mpc cosmological box with a spatial resolution of 109 pc. At z=0 our systems have an M vir = 6 − 8 × 10 ¹¹ M ⊙ . In several of out models we have observed how a well defined disk is formed inside the dark...
Article
Full-text available
We introduce a new set of simulations of a Milky Way like galaxy using the AMR code ART + hydrodynamics in a $\Lambda$CDM cosmogony. The simulation series is named GARROTXA and follow the formation of a late type galaxy from z=60 with a final virial mass of \sim$7.4$\times$10$^{11}$M$_{\odot}$. This system has no major mergers since z=3 and at z=0...
Article
Full-text available
We map the kinematics of stars in simulated galaxy discs with spiral arms using the velocity ellipsoid vertex deviation ($l_{\rm v}$). We use test particle simulations, and for the first time, fully self-consistent high-resolution N-body models. We compare our maps with the tight winding approximation model analytical predictions. We see that for a...
Article
In this work we shed new light in the nature of spiral arm structures in galaxies. We present a disk kinematic and dynamic study of MW like galaxies using complementary approaches: analytical models, test-particle simulations, pure N-body and cosmological N-body plus hydrodynamic simulations. Using collisionless N-body data we have found that model...
Article
N-body simulations conducted for kinematic analysis of stellar disk component -high number of disk particles, small time step and few parsecs spatial resolution - reveal two different behaviors for the spiral arm angular velocity. Whereas subdominant disk cases present transient spiral arm features corotating with particles, Milky Way like galax...
Article
Full-text available
High-resolution N-body simulations using different codes and initial condition techniques reveal two different behaviours for the rotation frequency of transient spiral arms like structures. Whereas unbarred discs present spiral arms nearly corotating with disc particles, strong barred models (bulged or bulgeless) quickly develop a bar–spiral struc...
Article
Full-text available
Test particle simulations of Milky Way type galactic disks are being conducted to map the evolution of the stellar large scale kinematic response to the bar and spiral structure. Second and third order moments of the velocity distribution function prove to be good indicators of both, the velocity ellipsoid misalignment near the arms and the bar, an...
Article
Full-text available
N-body and test particle simulations have been used to characterize the stellar streams in the galactic discs of Milky Way type galaxies. Tools such as the second and third order moments of the velocity ellipsoid and clustering methods -EM-WEKA and FoF- allow characterizing these kinematic structures and linking them to the stellar overdensities an...

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