Engineering topics

Rueda, J. A.

Publications and source records attributed to Rueda, J. A..

5 records

DOE OSTI2024

Occurrence of Gravitational Collapse in the Accreting Neutron Stars of Binary-driven Hypernovae

The binary-driven hypernova (BdHN) model proposes long gamma-ray bursts (GRBs) originate in binaries composed of a carbon–oxygen (CO) star and a neutron star (NS) companion. The CO core collapse generates a newborn NS and a supernova that triggers the GRB by accreting onto the NSs, rapidly transferring mass and angular momentum to them. This article aims to determine the conditions under which a black hole (BH) forms from NS collapse induced by the accretion and the impact on the GRB's observational properties and taxonomy. We perform three-dimensional, smoothed particle hydrodynamics simulations of BdHNe using up-to-date NS nuclear equations of state, with and without hyperons, and calculate the structure evolution in full general relativity. We assess the binary parameters leading either NS in the binary to the critical mass for gravitational collapse into a BH and its occurrence time, t col . We include a nonzero angular momentum of the NSs and find that t col ranges from a few tens of seconds to hours for decreasing NS initial angular momentum values. BdHNe I are the most compact (about 5 minute orbital period), promptly form a BH, and release ≳10 52 erg of energy. They form NS–BH binaries with tens of kiloyears merger timescales by gravitational-wave emission. BdHNe II and III do not form BHs, and release ~10 50 –10 52 erg and ≲10 50 erg of energy, respectively. They form NS–NS binaries with a range of merger timescales larger than for NS–BH binaries. In some compact BdHNe II, either NS can become supramassive, i.e., above the critical mass of a nonrotating NS. Magnetic braking by a 10 13 G field can delay BH formation, leading to BH–BH or NS–BH with tens of kiloyears merger timescales.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

Orbital Decay of Double White Dwarfs: Beyond Gravitational-wave Radiation Effects

The traditional description of the orbital evolution of compact-object binaries, like double white dwarfs (DWDs), assumes that the system is driven only by gravitational-wave (GW) radiation. However, the high magnetic fields with intensities of up to gigagausses measured in WDs alert a potential role of the electromagnetic (EM) emission in the evolution of DWDs. We evaluate the orbital dynamics of DWDs under the effects of GW radiation, tidal synchronization, and EM emission by a unipolar inductor generated by the magnetic primary and the relative motion of the nonmagnetic secondary. We show that the EM emission can affect the orbital dynamics for magnetic fields larger than megagausses. We applied the model to two known DWDs, SDSS J0651+2844 and ZTF J1539+5027, for which the GW radiation alone does not fully account for the measured orbital decay rate. We obtain upper limits to the primary's magnetic field strength, over which the EM emission causes an orbital decay faster than observed. The contribution of tidal locking and the EM emission is comparable, and together they can contribute up to 20% to the measured orbital decay rate. We show that the gravitational waveform for a DWD modeled as purely driven by GWs and including tidal interactions and EM emission can have large relative dephasing detectable in the mHz regime of frequencies relevant for space-based detectors like LISA. Therefore, including physics besides GW radiation in the waveform templates is essential to calibrate the GW detectors using known sources, e.g., ZTF J1539+5027, and to infer binary parameters.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

The morphology of the X-ray afterglows and of the jetted GeV emission in long GRBs

ABSTRACT We recall evidence that long gamma-ray bursts (GRBs) have binary progenitors and give new examples. Binary-driven hypernovae (BdHNe) consist of a carbon–oxygen core (COcore) and a neutron star (NS) companion. For binary periods ∼5 min, the COcore collapse originates the subclass BdHN I characterized by (1) an outstanding supernova (SN; the ‘SN-rise’); (2) a black hole (BH), born from the NS collapse by SN matter accretion, leading to a GeV emission with luminosity $L_{\rm GeV} = A_{\rm GeV}\, t^{-\alpha _{\rm GeV}}$, observed only in some cases; and (3) a new NS (νNS), born from the SN, originating from the X-ray afterglow with $L_\mathrm{ X} = A_{\rm X}\, t^{-\alpha _{\rm X}}$, observed in all BdHN I. We record 378 sources and present for four prototype GRBs 130427A, 160509A, 180720B, and 190114C: (1) spectra, luminosities, SN-rise duration; (2) AX, αX = 1.48 ± 0.32, and (3) the νNS spin time evolution. We infer (i) AGeV, αGeV = 1.19 ± 0.04 and (ii) the BdHN I morphology from time-resolved spectral analysis, three-dimensional simulations, and the GeV emission presence/absence in 54 sources within the Fermi-Large Area Telescope boresight angle. For 25 sources, we give the integrated and time-varying GeV emission, 29 sources have no GeV emission detected and show X/gamma-ray flares previously inferred as observed along the binary plane. The 25/54 ratio implies the GeV radiation is emitted within a cone of half-opening angle ≈60° from the normal to the orbital plane. We deduce BH masses of 2.3–8.9 M⊙ and spin of 0.27–0.87 by explaining the GeV emission from the BH rotational energy extraction, while their time evolution validates the BH mass–energy formula.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2019

SPH Simulations of the Induced Gravitational Collapse Scenario of Long Gamma-Ray Bursts Associated with Supernovae

We present the first three-dimensional smoothed particle hydrodynamics simulations of the induced gravitational collapse scenario of long-duration gamma-ray bursts (GRBs) associated with supernovae (SNe). We simulate the SN explosion of a carbon–oxygen core (CO core ) forming a binary system with a neutron star (NS) companion. We follow the evolution of the SN ejecta, including their morphological structure, subject to the gravitational field of both the new NS (νNS) formed at the center of the SN and the one of the NS companion. We compute the accretion rate of the SN ejecta onto the NS companion, as well as onto the νNS from SN matter fallback. We determine the fate of the binary system for a wide parameter space including different CO core and NS companion masses, orbital periods, and SN explosion geometry and energies. We identify, for selected NS nuclear equations of state, the binary parameters leading the NS companion, by hypercritical accretion, either to the mass-shedding limit or to the secular axisymmetric instability for gravitational collapse to a black hole (BH), or to a more massive, fast-rotating, stable NS. We also assess whether the binary remains gravitationally bound after the SN explosion, hence exploring the space of binary and SN explosion parameters leading to νNS–NS and νNS–BH binaries. As a result, the consequences of our results for the modeling of long GRBs, i.e., X-ray flashes and binary-driven hypernovae, are discussed.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2018

A GRB Afterglow Model Consistent with Hypernova Observations

In this paper we describe the afterglows of the long gamma-ray-burst (GRB) 130427A within the context of a binary-driven hypernova. The afterglows originate from the interaction between a newly born neutron star ($ν$NS), created by an Ic supernova (SN), and a mildly relativistic ejecta of a hypernova (HN). Such an HN in turn results from the impact of the GRB on the original SN Ic. The mildly relativistic expansion velocity of the afterglow ($Γ ~ 3$) is determined, using our model-independent approach, from the thermal emission between 196 and 461 s. The power law in the optical and X-ray bands of the afterglow is shown to arise from the synchrotron emission of relativistic electrons in the expanding magnetized HN ejecta. Two components contribute to the injected energy: the kinetic energy of the mildly relativistic expanding HN and the rotational energy of the fast-rotating highly magnetized $ν$NS. We reproduce the afterglow in all wavelengths from the optical (10 14 Hz) to the X-ray band (10 19 Hz) over times from 604 s to 5.18 × 10 6 s relative to the Fermi-GBM trigger. Initially, the emission is dominated by the loss of kinetic energy of the HN component. After 10 5 s the emission is dominated by the loss of rotational energy of the $ν$NS, for which we adopt an initial rotation period of 2 ms and a dipole plus quadrupole magnetic field of $\lesssim$ 7 × 10 12 G or ~10 14 G. This scenario with a progenitor composed of a CO core and an NS companion differs from the traditional ultra-relativistic-jetted treatments of the afterglows originating from a single black hole.

79 ASTRONOMY AND ASTROPHYSICS↗