Progenitors of Long-Duration Gamma-ray Bursts

Roy, A.B.

doi:10.3390/galaxies9040079

Cited by 6 publications

(1 citation statement)

References 92 publications

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“…The assumption about the nonuniform explosion was made in order to explain observational signatures of SN which are different from a SN type II-P and to obtain spectrum and light curves similar to the one of gamma-ray bursts (GRBs) during the prompt phase. Thus, the engine of GRBs occurs to be related to nuclear energy of the explosion of a PISN (see also Fryer et al (2001); Kozyreva & Blinnikov (2015); Gilmer et al (2017); Chatzopoulos et al (2019); Roy (2021)). In order to conceptualize the phenomena, we propose to tackle this problem from another perspective.…”

Section: Pisne -Grb Connectionmentioning

confidence: 99%

On the emergence of a new instability during core-collapse of very massive stars

Kalashnikov,

Baranov,

Chardonnet

et al. 2021

Preprint

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The process of uniform supernovae explosions (SNe) is well investigated for all their types. However, observational data suggests that the SNe could be not spherically-symmetric. Modern multidimensional simulations of SNe demonstrate development of hydrodynamical instabilities during the explosion phase. But the configuration of a star and inhomogeneities prior to explosion could strongly affect how the SNe develops. In a number of papers on numerical modeling of pair-instability supernovae explosion (PISNe) considered the case when thermonuclear energy in the central region of a massive star is introduced by the series of several hot spots. It leads to the appearance of many fragments of hot matter behind the divergence shock wave. An observable manifestation of this may be the presence of peaks on light curves of gamma-ray burst associated with explosions of massive stars.The physical nature of such inhomogeneities is not evident and the number and size of spots is a conjecture. In this work, we study the possibility of formation of these inhomogeneities at the stage of the core-collapse (CC) in a massive star. To check this assumption, we chose analytic self-similar model of CC and investigated stability of solutions obtained from it with respect to small multidimensional perturbations. It shows there are no conditions where the collapse of a very massive star may remain stable, although, for a less massive star, it is possible. Using obtained relations, we found characteristic features of developing instability, thereby making it possible to estimate the amount and characteristic size of the inhomogeneities.

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Section: Pisne -Grb Connectionmentioning

confidence: 99%

On the emergence of a new instability during core-collapse of very massive stars

Kalashnikov,

Baranov,

Chardonnet

et al. 2021

Preprint

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Europium enrichment and hierarchical formation of the Galactic halo

L.¹,

G.²,

F.³

2023

A&A

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Context. The origin of the large star-to-star variation of the [Eu/Fe] ratios observed in the extremely metal-poor (at [Fe/H] ≤ −3) stars of the Galactic halo is still a matter of debate. Aims. In this paper, we explore this problem by putting our stochastic chemical evolution model in the hierarchical clustering framework, with the aim of explaining the observed spread in the halo. Methods. We compute the chemical enrichment of Eu occurring in the building blocks that have possibly formed the Galactic halo. In this framework, the enrichment from neutron star mergers can be influenced by the dynamics of the binary systems in the gravitational potential of the original host galaxy. In the least massive systems, the neutron stars can merge outside the host galaxy and so only a small fraction of newly produced Eu can be retained by the parent galaxy itself. Results. In the framework of this new scenario, the accreted merging neutron stars are able to explain the presence of stars with sub-solar [Eu/Fe] ratios at [Fe/H] ≤ −3, but only if we assume a delay time distribution for merging of the neutron stars ∝t−1.5. We confirm the correlation between the dispersion of [Eu/Fe] at a given metallicity and the fraction of massive stars which give origin to neutron star mergers. The mixed scenario, where both neutron star mergers and magneto-rotational supernovae do produce Eu, can explain the observed spread in the Eu abundance also for a delay time distribution for mergers going either as ∝t−1 or ∝t−1.5.

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On the hosts of neutron star mergers in the nearby Universe

Cavallo¹,

Greggio

2023

Monthly Notices of the Royal Astronomical Society

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Recently, the characterisation of binary systems of neutron stars has become central in various fields such as gravitational waves, gamma-ray bursts (GRBs), and the chemical evolution of galaxies. In this work, we explore possible observational proxies that can be used to infer some characteristics of the delay time distribution (DTD) of neutron star mergers (NSMs). We construct a sample of model galaxies that fulfils the observed galaxy stellar mass function, star formation rate versus mass relation, and the cosmic star formation rate density. The star formation history of galaxies is described with a log-normal function characterised by two parameters: the position of the maximum and the width of the distribution. We assume a theoretical DTD that mainly depends on the lower limit and the slope of the distribution of the separations of the binary neutron stars systems at birth. We find that the current rate of NSMs ($\mathcal {R}=320^{+490}_{-240}$ Gpc−3yr−1) requires that ∼0.3 per cent of neutron star progenitors lives in binary systems with the right characteristics to lead to a NSM within a Hubble time. We explore the expected relations between the rate of NSMs and the properties of the host galaxy. We find that the most effective proxy for the shape of the DTD of NSMs is the current star formation activity of the typical host. At present, the fraction of short-GRBs observed in star-forming galaxies favours DTDs with at least $\sim 40\%$ of mergers within 100 Myr. This conclusion will be put on a stronger basis with larger samples of short-GRBs with host association (e.g. 600 events at z ≤ 1).

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Progenitors of Long-Duration Gamma-ray Bursts

Cited by 6 publications

References 92 publications

On the emergence of a new instability during core-collapse of very massive stars

On the emergence of a new instability during core-collapse of very massive stars

Europium enrichment and hierarchical formation of the Galactic halo

On the hosts of neutron star mergers in the nearby Universe

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