arXiv subjects

Enrique Moreno Mendez

Publications and source records attributed to Enrique Moreno Mendez.

7 recordsLinked to original sources

arXiv2025

Three-dimensional simulations of accretion disks in pre-CE systems

Before a binary system enters into a common envelope (CE) phase, accretion from the primary star onto the companion star through Roche Lobe overflow (RLOF) will lead to the formation of an accretion disk, which may generate jets. Accretion before and during the CE may alter the outcome of the interaction. Previous studies have considered different aspects of this physical mechanism. Here we study the properties of an accretion disk formed via 3D hydrodynamic simulations of the RLOF mass transfer between a 7 M$_\odot$, red supergiant star and a 1.4 M$_\odot$, neutron star companion. We simulate only the volume around the companion for improved resolution. We use a 1D implicit MESA simulation of the evolution of the system during 30,000 years between the on-set of the RLOF and the CE to guide the binary parameters and the mass-transfer rate, while we simulate only 21 years of the last part of the RLOF in 3D using an ideal gas isothermal equation of state. We expect that a pre-CE disk under these parameters will have a mass of $\sim 5\times 10^{-3}$ M$_\odot$ and a radius of $\sim$40 R$_\odot$ with a scale height of $\sim$5 R$_\odot$. The temperature profile of the disk is shallower than that predicted by the formalism of Shakura and Sunyaev, but more reasonable cooling physics would need to be included. We stress test these results with respect to a number of physical and numerical parameters, as well as simulation choices, and we expect them to be reasonable within a factor of a few for the mass and 15% for the radius. We also contextualize our results within those presented in the literature, in particular with respect to the dimensionality of simulations and the adiabatic index. We discuss the measured accretion rate in the context of the Shakura and Sunyaev formalism and debate the viscous mechanisms at play, finishing with a list of prospects for future work.

astro-ph.SR↗

arXiv2022

Jets in Common Envelopes: a low mass main sequence star in a red giant

We present small-scale three-dimensional hydrodynamical simulations of the evolution of a 0.3Msun main sequence star which launches two perpendicular jets within the envelope of a 0.88Msun red giant. Based on previous large-scale simulations, we study the dynamics of the jets either when the secondary star is grazing, when it has plunged-in, or when it is well-within the envelope of the red giant (in each stage for ~11 days). The dynamics of the jets through the common envelope (CE) depend on the conditions of the environment as well as on their powering. In the grazing stage and the commencement of the plunge self-regulated jets need higher efficiencies to break out of the envelope of the RG. Deep inside the CE, on the timescales simulated, jets are choked independently of whether they are self-regulated or constantly powered. Jets able to break out of the envelope of the RG in large-scale simulations, are choked in our small-scale simulations. The accreted angular momentum onto the secondary star is not large enough to form a disk. The mass accretion onto the MS star is 1-10% of the Bondi-Hoyle-Littleton rate (~1e-3 - 1e-1 Msun yr/s). High luminosity emission, from X-rays to UV and optical, is expected if the jets break out of the CE. Our simulations illustrate the need for inclusion of more realistic accretion and jet models in the dynamical evolution of the CEs.

astro-ph.HE↗

arXiv2020

Disk formation and jet inclination effects in Common Envelopes

The evolution and physics of the common envelope (CE) phase are still not well understood. Jets launched from a compact object during this stage may define the evolutionary outcome of the binary system. We focus on the case in which jets are launched from a neutron star (NS) engulfed in the outer layers of a red giant (RG). We run a set of three-dimensional hydrodynamical simulations of jets with different luminosities and inclinations. The luminosity of the jet is self-regulated by the mass accretion rate and an efficiency $η$. Depending on the value of $η$ the jet can break out of the BHL bulge ("successful jet") and aligns against the incoming wind, in turn, it will realign in favour of the direction of the wind. The jet varies in size and orientation and may present quiescent and active epochs. The inclination of the jet and the Coriolis and centrifugal forces, only slightly affect the global evolution. As the accretion is hypercritical, and the specific angular momentum is above the critical value for the formation of a disk, we infer the formation of a disk and launching of jets. The disks' mass and size would be $\sim$10$^{-2}$~M$_\odot$ and $\gtrsim 10^{10}$ cm, and it may have rings with different rotation directions. In order to have a successful jet from a white dwarf, the ejection process needs to be very efficient ($η\sim$0.5). For main sequence stars, there is not enough energy reservoir to launch a successful jet.

astro-ph.HE↗

arXiv2018

Self-regulating jets during the Common Envelope phase

Jets launched from a compact object (CO) during a common envelope (CE) may play a key role in the evolution of the system, and may also be an efficient removal channel for its material. In this work we study, through a large set of three-dimensional hydrodynamic simulations, the effects that jets launched from either a black hole (BH) or a neutron star (NS) have during a CE phase. The jet is self-consistently powered by a fraction ($η$) of the mass accretion rate that reaches the CO. For low mass accretion efficiencies ($η$<0.1\%), the jet is not able to drill through the material accreting onto the CO and forms a bulge around it. For higher efficiencies, the jet is able to drill through the bulge and in intermediate efficiencies ($η\sim$1-5\%) may produce an oscillating mass accretion rate behavior. We find that the jet may deposit enough energy to unbind the outer layers of the CE. The self-regulated jets present variability in size and orientation while their cocoons expand smoothly over the CE. The mass accretion rate initially decreases due to the ram pressure of the cocoon. If the launched jet is not able to drill through the bulge, the accretion is such that it may convert a NS into a BH within a decade or double the mass of a BH in a few years. If a jet is present, it deposits enough energy to unbind the outer layers of the CE and the system evolves into a grazing envelope, configuration.

astro-ph.HE↗

arXiv2014

Neutrino Oscillation as a constraint in the dynamics of Pop III Gamma Ray Bursts

Population III stars are believed to be rapidly-rotating sources with a mass range of hundreds to thousand of solar masses. Masses larger than 260 M$_\odot$ are expected to collapse resulting in central rotating Kerr black holes with large rotation parameter a. Due to particle-antiparticle asymmetry is small, we use the neutrino effective potential up to order $1/M_W^4$ in a magnetized plasma at the base of the ejecta to constrain the rotation parameter by means of neutrino oscillations. Additionally, we investigate the implications in the magnetic field, temperature and electron asymmetry.

astro-ph.HE↗

arXiv2010

The need for hypercritical accretion in massive black-hole binaries with large Kerr parameters

Recent measurements of the Kerr parameters of the black holes in M33 X-7 and LMC X-1 yield a*=0.84\pm0.05 and a*=0.90^{+.04}_{-.09} respectively. We study massive binary evolution scenarios that can reproduce such high values for the Kerr parameters. We first discuss a model with Case C mass transfer leading to a common envelope and tidal synchronization of the primary before it collapses into a black hole. We also study a Case M evolution model (which involves tidally-locked, rotationally-mixed, chemically-homogeneous stars in a close binary). Our analysis suggests that, regardless of the specific scenario, the observed Kerr parameters for the black holes in M33 X-7 and LMC X-1 had to be obtained through hypercritical mass accretion.

astro-ph.HE↗

arXiv2010

GRB/HN from Kerr Black Holes in Binaries

The Collapsar model, in which a massive star (greater than 20 solar masses) fails to produce a SN and forms a BH, provides the main framework for understanding long Gamma-Ray Bursts (GRB) and the accompanying hypernovae (HN). However, single massive-star models that explain the population of pulsars, predict cores that rotate too slowly to produce GRBs/HNe. We present a model of binary evolution that allows the formation of Kerr black holes (BH) where the spin of the BH can be estimated from the pre-collapse orbit, and use the Blandford-Znajek (BZ) mechanism to estimate the available energy for a GRB/HN. A population synthesis study shows that this model can account for both, the long GRB and the subluminous GRB populations.

astro-ph.HE↗