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David Morales-Zapien

Publications and source records attributed to David Morales-Zapien.

2 recordsLinked to original sources

G objects as Primordial Black Hole-Neutron Star Remnants: Population Modeling and Multi-Wavelength Observables

The nature of the so-called G objects orbiting the Galactic Center remains unresolved. These sources exhibit compact Br$γ$ emission, extreme infrared colors, and remarkable dynamical stability through close passages to the central supermassive black hole, challenging conventional interpretations as stars or unbound gas clouds. We investigate the hypothesis that G objects are the remnants of neutron stars that have been converted into low-mass black holes through the capture of primordial black holes, a viable dark-matter candidate. We construct a population-level framework linking the abundance and spatial distribution of these remnants to the neutron-star population, the inner dark-matter density profile, and the primordial black-hole mass and abundance. Within this framework, the observed G-object population and the long-standing deficit of ordinary radio pulsars in the Galactic Center emerge as complementary consequences of the same conversion process. We further identify a suite of observational signatures-across infrared, radio, X-ray, and microlensing channels-that render this scenario empirically testable and distinguishable from stellar-envelope models. Our results show that G objects can act as sensitive probes of compact-object capture physics and of dark matter on sub-galactic scales.

astro-ph.HE

Finite temperature effects on g-modes of inviscid neutron stars

We study the effect of temperature on secular, compositional $g$-modes in the core of inviscid neutron stars. Using a chiral $SU(2)_f$ sigma model, we construct isentropic temperature profiles for hot and dense matter and find that the frequency of the global core $g$-mode's dependence on temperature is governed by the nuclear symmetry energy slope parameter $L$. As a result, the $g$-mode frequency of a warm neutron star can be either higher or lower than that of its cold counterpart, depending on $L$. Our results highlight the interplay of thermal effects and composition gradients, and demonstrate the potential of neutron star $g$-mode observations to constrain the density dependence of the symmetry energy.

astro-ph.HE