arXiv subjects

Elizabeth Moreno-Hilario

Publications and source records attributed to Elizabeth Moreno-Hilario.

5 recordsLinked to original sources

arXiv2026

Reconstructing the Globular Cluster Initial Mass Function from Present-Day Globular Cluster Systems

The near-universal turnover mass of the present-day globular cluster mass function (GCMF), $M_{\rm TO} \sim 2 \times 10^5\ {\rm M_\odot}$, is a well established observational feature across galaxies of different types and masses, providing an important empirical benchmark for understanding the globular cluster initial mass function (GCIMF). Competing explanations of this property invoke either dynamical evolution from an initial power-law distribution or an imprint of cluster formation physics. We address this problem by reconstructing the high-mass regime of the GCIMF by inverting the mass loss due to dynamical evolution of present-day globular cluster systems across a wide range of host galaxy masses. Our method is based on an environment-dependent mass-loss model calibrated by direct $N$-body simulations in time-dependent tidal fields, enabling a mapping between observed cluster masses and their progenitor values without assuming a priori a functional form for the GCIMF. We apply our method to galaxies spanning halo masses of $\sim10^{9}$ - $10^{12}\ {\rm M_\odot}$, combining systems with individually measured globular cluster masses as well as large statistical samples constructed from observed global properties. The recovered GCIMFs are systematically shifted towards higher masses and exhibit a power-law behavior at the high-mass end. The inferred slopes vary across galaxies and show a strong correlation with host halo mass, with more massive galaxies exhibiting steeper high-mass slopes. Our results suggest that the slope of the GCIMF depends on the galactic properties and provides a direct empirical link between present-day globular cluster systems and their high-redshift progenitors.

astro-ph.GA↗

arXiv2025

Metal-rich stellar counterpart of the Radcliffe Wave and the 3D chemical footprints of the Milky Way spiral arms

Mapping the Milky Way spiral arms in the vertical direction remains a challenging task that has received little attention. Taking advantage of recent results that link the position of the Galactic spiral arms to metal-rich regions in the disc, we analyse a sample of young giant stars from {\it Gaia} DR3 and use their metallicity distribution to produce a 3D metallicity excess map. The map shows signatures of the spiral arms, whose vertical height vary across the Galactic disc, reaching up to 400 pc in amplitude and exhibiting vertical asymmetries with respect to the mid-plane. Specifically, the Perseus arm displays a high vertical asymmetry consistent with the Galactic warp. Moreover, we find evidence of a metal-rich stellar structure that undulates vertically, nearly in phase with the arrangement of star-forming regions named the Radcliffe Wave. This new structure is larger and extends beyond the Radcliffe Wave, reaching vertical amplitudes of $\sim$ 270 pc and extending for at least 4 kpc in length. We confirm that for at least half of its length this Extended Radcliffe Wave is the inner edge of the Local Arm. The finding of a metal-rich stellar counterpart of the Radcliffe Wave shows that mapping the three-dimensional metallicity distribution of young stellar populations reveals key information about the structures and chemical enrichment in the Galactic disc.

astro-ph.GA↗

arXiv2024

The Brown Dwarf Kinematics Project (BDKP). VI. Ultracool Dwarf Radial and Rotational Velocities from SDSS/APOGEE High-resolution Spectroscopy

We present precise measurements of radial (RV) and projected rotational ($v\sin{i}$) velocities, effective temperatures, and surface gravities of a sample of 258 M6 to L2 dwarfs with multi-epoch, high-resolution ($λ/Δλ$ = 22500), near-infrared (1.514-1.696 $μ$m) spectroscopic observations reported in the Apache Point Observatory Galactic Evolution Experiment (APOGEE) Data Release 17. The spectra were modeled using a Markov Chain Monte Carlo forward-modeling method which achieved median precisions of $σ_\text{RV}$ = 0.4 km s$^{-1}$ and $σ_{v\sin{i}}$ = 1.1 km s$^{-1}$. One-half of our sample (138 sources) are previously known members of nearby young clusters and moving groups, and we identified three new kinematic members of the Argus or Carina Near moving groups, 2MASS J05402570+2448090, 2MASS J14093200+4138080, and 2MASS J21272531+5553150. Excluding these sources, we find that the majority of our sample has kinematics consistent with the Galactic thin disk, and eleven sources are associated with the intermediate thin/thick disk. The field sample has a velocity dispersion of 38.2$\pm$0.3 km s$^{-1}$, equivalent to an age of 3.30$\pm$0.19 Gyr based on empirical age-velocity dispersion relations; and a median $v\sin{i}$ of 17 km s$^{-1}$. For 172 sources with multi-epoch observations, we identified 37 as having significant radial velocity variations, and determined preliminary orbit parameters for 26 sources with four or more epochs. For 40 sources with photometric variability periods from the literature less than 5 days and $v\sin{i}$ $>$ 20 km s$^{-1}$, we find a decline in projected radii $R\sin{i}$ with age congruent with evolutionary models. Finally, we also present multi-epoch RV and vsini measurements for additional 444 candidate ultracool dwarfs.

astro-ph.SR↗

arXiv2023

The influence of globular cluster evolution on the specific frequency in dwarf galaxies

Dwarf galaxies are known to exhibit an unusual richness in numbers of globular clusters (GCs), property quantified by the specific frequency ($S_N$), which is high for dwarf and giant elliptical galaxies, but with a minimum for intermediate-mass galaxies. In this work we study the role that GC evolution has in setting this trend, for which we use ${\it N}$-body simulations to evolve GCs in dwarf galaxies and quantify their disruption efficiency. We selected five individual dwarf galaxies from a high-resolution cosmological simulation, which includes GC formation and follow-up of their paths inside the host galaxy. Then, the tidal history of each GC is coupled to NBODY6++GPU to produce ${\it N}$-body models that account for both, the interaction of GCs with their galactic environment and their internal dynamics. This results in a GC mass loss parameterization to estimate dissolution times and mass loss rates after a Hubble time. GC evolution is sensitive to the particular orbital histories within each galaxy, but the overall result is that the amount of mass that GC systems lose scales with the mass (and density) of the host galaxy, i.e., the GC mass loss efficiency is lowest in low-mass dwarfs. After a 12 Gyr evolution all simulated GC systems retain an important fraction of their initial mass (up to 25%), in agreement with the high GC to field star ratios observed in some dwarfs, and supports the scenario in which GC disruption mechanisms play an important role in shaping the GC specific frequency in dwarf galaxies.

astro-ph.GA↗

arXiv2017

Microcanonical-ensemble computer simulation of the high-temperature expansion coefficients of the Helmholtz free-energy of a Square-well fluid

The Microcanonical Ensemble computer simulation method (MCE) is used to evaluate the perturbation terms $A_i$ of the Helmholtz free energy of a Square-Well (SW) fluid. The MCE method offers a very efficient and accurate procedure for the determination of perturbation terms of discrete-potential systems such as the SW fluid and surpass the standard NVT Canonical Ensemble Monte Carlo method, allowing the calculation of the first six expansion terms. Results are presented for the case of a SW potential with attractive ranges $1.1 \le λ\le 1.8$. Using semiempirical representation of the MCE values for $A_i$, we also discuss the accuracy in the determination of the phase diagram of this system.

cond-mat.stat-mech↗