Search

Hypernovae powered by magnetic jets launched from the surface of rapidly rotating millisecond magnetars are one of the leading models to explain broad-lined Type Ic supernovae (SNe Ic-BL), and have been implicated as an important source of metal enrichment in the early Universe. We investigate the nucleosynthesis in such jet-driven hypernovae using a parameterised, but physically motivated, approach that analytically relates an artificially injected jet energy flux to the power available from the energy in differential rotation in the proto-neutron star. We find ejected $^{56}\mathrm{Ni}$ masses of $0.05\,\mathrm{M}_\odot - 0.45\,\mathrm{M}_\odot$ in our most energetic models with explosion energy $>10^{52}\,\mathrm{erg}$. This is in good agreement with the range of observationally inferred values for SNe Ic-BL. The $^{56}\mathrm{Ni}$ is mostly synthesised in the shocked stellar envelope, and is therefore only moderately sensitive to the jet composition. Jets with a high electron fraction $Y_\mathrm{e}=0.5$ eject more $^{56}\mathrm{Ni}$ by a factor of 2 than neutron-rich jets. We can obtain chemical abundance profiles in good agreement with the average chemical signature observed in extremely metal-poor (EMP) stars presumably polluted by hypernova ejecta. Notably, $\mathrm{[Zn/Fe]} \gtrsim 0.5$ is consistently produced in our models. For neutron-rich jets, there is a significant r-process component, and agreement with EMP star abundances in fact requires either a limited contribution from neutron-rich jets or a stronger dilution of r-process material in the interstellar medium than for the slow SN ejecta outside the jet. The high $\mathrm{[C/Fe]}\gtrsim 0.7$ observed in many EMP stars cannot be consistently achieved due to the large mass of iron in the ejecta, however, and remains a challenge for jet-driven hypernovae based on the magneto-rotational mechanism.

Fallback in core-collapse supernovae plays a crucial role in determining the properties of the compact remnants and of the ejecta composition. We perform three-dimensional simulations of mixing and fallback for selected non-rotating supernova models to study how explosion energy and asymmetries correlate with the remnant mass, remnant kick, and remnant spin. We find that the strongest kick and spin is imparted by partial fallback in an asymmetric explosion. Black hole (BH) kicks of several hundred $\mathrm{km}\,\mathrm{s}^{-1}$ and spin parameters of $\mathord{\sim}0.25$ can be obtained in this scenario. If the initial explosion energy barely exceeds the envelope binding energy, stronger fallback results, and the remnant kick and spin remain small. If the explosion energy is high with respect to the envelope binding energy, there is little fallback with a small effect on the remnant kick, but the spin-up by fallback can be substantial. For a non-rotating $12\,\mathrm{M}_\odot$ progenitor, we find that the neutron star (NS) is spun up to millisecond periods. The high specific angular momentum of the fallback material can also lead to disk formation around black holes. Fallback may thus be a pathway towards millisecond-magnetar or collapsar-type engines for hypernovae and gamma-ray bursts that does not require rapid progenitor rotation. Within our small set of simulations, none reproduced the peculiar layered fallback necessary to explain the metal-rich iron-poor composition of many carbon-enhanced metal-poor (CEMP) stars. Models with different explosion energy and different realisations of asymmetries may, however, be compatible with CEMP abundance patterns., Comment: 12 pages, 13 figures, accepted for publication in MNRAS

Binary driven hypernova (BdHN) models long gamma-ray burst (GRBs) as occurring in the binary systems involving a carbon-oxygen core (CO$_{\rm core}$) and a companion neutron star (NS) or a black hole (BH). This model, first proposed in 2012, succeeds and improves upon the fireshell model and the induced gravitational collapse (IGC) paradigm. After nearly a decade of development, the BdHN model has reached a nearly complete structure, explaining all the observables of long bursts into its theoretical framework, and has given a refined classification of long GRBs according to the original properties of the progenitors. In this article, we present a summary of the BdHN model and the physical processes at work in each of the envisaged Episodes during its occurrence and lifetime, duly contextualized in the framework of GRB observations., Comment: Review paper, Published in IJMPD, Volume No. 30, Issue No. 15

Although true metal-free "Population III" stars have so-far escaped discovery, their nature, and that of their supernovae, is revealed in the chemical products left behind in the next generations of stars. Here we report the detection of an ultra-metal poor star in the Sculptor dwarf spheroidal galaxy, AS0039. With [Fe/H]$_{\rm LTE}=-4.11$, it is the most metal-poor star so far discovered in any external galaxy. Contrary to the majority of Milky Way stars at this metallicity, AS0039 is clearly not enhanced in carbon, with [C/Fe]$_{\rm LTE}=-0.75$ and A(C)=+3.60, making it the lowest detected carbon abundance in any star to date. It furthermore lacks $\alpha$-element uniformity, having extremely low [Mg/Ca]$_{\rm NLTE}=-0.60$ and [Mg/Ti]$_{\rm NLTE}=-0.86$, in stark contrast with the near solar ratios observed in C-normal stars within the Milky Way halo. The unique abundance pattern indicates that AS0039 formed out of material that was predominantly enriched by a $\sim$20$ M_\odot$ progenitor star with an unusually high explosion energy $E=10\times10^{51}$ erg. The star AS0039 is thus one of the first observational evidence for zero-metallicity hypernovae and provides a unique opportunity to investigate the diverse nature of Population III stars., Comment: Accepted in ApJL, 7 pages, 3 figures, 1 table, and an appendix (1 figure and 3 tables)

Powerful astrophysical sources of chiral influence on biomolecules in the Galaxy and outside it in the cosmic scenario of the origin of life are studied. The effect of such sources and their precursors on sugars is based on right circularly polarized ultraviolet from bremsstrahlung of positrons produced by the radioactive decay of cobalt 56 Co. The maximum mass of radioactive cobalt 56Co is reached during Hypernova explosions; it can exceed ten solar masses. It was shown that the power of chiral ultraviolet from the Hypernova exceeds that from the type 1a Supernova and relativistic fireball approximately by factors of 4.5 and 9, respectively.

It was recently pointed out that very energetic subclasses of supernovae (SNe), like hypernovae and superluminous SNe, might host ultra-strong magnetic fields in their core. Such fields may catalyze the production of feebly interacting particles, changing the predicted emission rates. Here we consider the case of axion-like particles (ALPs) and show that the predicted large scale magnetic fields in the core contribute significantly to the ALP production, via a coherent conversion of thermal photons. Using recent state-of-the-art SN simulations including magnetohydrodynamics, we find that if ALPs have masses $m_a \sim {\mathcal O}(10)\, \rm MeV$, their emissivity via magnetic conversions is over two orders of magnitude larger than previously estimated. Moreover, the radiative decay of these massive ALPs would lead to a peculiar delay in the arrival times of the daughter photons. Therefore, high-statistics gamma-ray satellites can potentially discover MeV ALPs in an unprobed region of the parameter space and shed light on the magnetohydrodinamical nature of the SN explosion., 6 pages, 3 Figures

Stellar evolution theory predicts a "gap" in the black hole birth function caused by the pair instability. Presupernova stars that have a core mass below some limiting value, Mlo, after all pulsational activity is finished, collapse to black holes, whereas more massive ones, up to some limiting value, Mhi, explode, promptly and completely, as pair-instability supernovae. Previous work has suggested Mlo is approximately 50 solar masses and Mhi is approximately 130 solar masses. These calculations have been challenged by recent LIGO observations that show many black holes merging with individual masses, Mlo is least some 65 solar masses. Here we explore four factors affecting the theoretical estimates for the boundaries of this mass gap: nuclear reaction rates, evolution in detached binaries, rotation, and hyper-Eddington accretion after black hole birth. Current uncertainties in reaction rates by themselves allow Mlo to rise to 64 solar masses and Mhi as large as 161 solar masses. Rapid rotation could further increase Mlo to about 70 solar masses, depending on the treatment of magnetic torques. Evolution in detached binaries and super-Eddington accretion can, with great uncertainty, increase Mlo still further. Dimensionless Kerr parameters close to unity are allowed for the more massive black holes produced in close binaries, though they are generally smaller., 16 pages, 4 figure panels, 6 tables, submitted to ApJ

In the binary-driven hypernova model of long gamma-ray bursts, a carbon&ndash, oxygen star explodes as a supernova in the presence of a neutron star binary companion in close orbit. Hypercritical (i.e., highly super-Eddington) accretion of the ejecta matter onto the neutron star sets in, making it reach the critical mass with consequent formation of a Kerr black hole. We have recently shown that, during the accretion process onto the neutron star, fast neutrino flavor oscillations occur. Numerical simulations of the above system show that a part of the ejecta stays bound to the newborn Kerr black hole, leading to a new process of hypercritical accretion. We address herein, also for this phase of the binary-driven hypernova, the occurrence of neutrino flavor oscillations given the extreme conditions of high density (up to 1012 g cm&minus, 3) and temperatures (up to tens of MeV) inside this disk. We estimate the behavior of the electronic and non-electronic neutrino content within the two-flavor formalism (&nu, e&nu, x) under the action of neutrino collective effects by neutrino self-interactions. We find that in the case of inverted mass hierarchy, neutrino oscillations inside the disk have frequencies between &sim, (105&ndash, 109) s&minus, 1, leading the disk to achieve flavor equipartition. This implies that the energy deposition rate by neutrino annihilation (&nu, +&nu, &macr, &rarr, e&minus, +e+) in the vicinity of the Kerr black hole is smaller than previous estimates in the literature not accounting for flavor oscillations inside the disk. The exact value of the reduction factor depends on the &nu, e and &nu, x optical depths but it can be as high as &sim, 5. The results of this work are a first step toward the analysis of neutrino oscillations in a novel astrophysical context, and as such, deserve further attention.

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 (CO$_{\rm core}$) and a neutron star (NS) companion. For binary periods $\sim 5$ min, the CO$_{\rm core}$ collapse originates the subclass BdHN I characterized by: 1) an energetic supernova (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; 3) a new NS ($\nu$NS), born from the SN, originating the X-ray afterglow with $L_X = A_{\rm X}\,t^{-\alpha_{\rm X}}$, observed in all BdHN I. We record $378$ sources and present for four prototypes GRBs 130427A, 160509A, 180720B and 190114C: 1) spectra, luminosities, SN-rise duration; 2) $A_X$, $\alpha_X=1.48\pm 0.32$, and 3) the $\nu$NS spin time-evolution. We infer a) $A_{\rm GeV}$, $\alpha_{\rm GeV}=1.19 \pm 0.04$; b) the BdHN I morphology from time-resolved spectral analysis, three-dimensional simulations, and the GeV emission presence/absence in $54$ sources within the Fermi-LAT 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 $\approx 60^{\circ}$ from the normal to the orbital plane. We deduce BH masses $2.3$-$8.9~M_\odot$ and spin $0.27$-$0.87$ by explaining the GeV emission from the BH energy extraction, while their time evolution validates the BH mass-energy formula., Comment: Accepted for publication by MNRAS on March 5, 2021; in press

Magnetic fields can play a major role in the dynamics of outstanding explosions associated to violent events such as GRBs and hypernovae, since they provide a natural mechanism to harness the rotational energy of the central proto-neutron star and power relativistic jets through the stellar progenitor. As the structure of such fields is quite uncertain, most numerical models of MHD-driven core-collapse supernovae consider an aligned dipole as initial magnetic field, while the field's morphology can actually be much more complex. We present three-dimensional simulations of core-collapse supernovae with more realistic magnetic structures, such as quadrupolar fields and, for the first time, an equatorial dipolar field. Configurations other than an aligned dipole produce weaker explosions and less collimated outflows, but can at the same time be more efficient in extracting the rotational energy from the PNS. This energy is then stored in the surroundings of the PNS, rather than powering the polar jets. A significant axial dipolar component is also produced by models starting with a quadrupolar field, pointing to an effective dynamo mechanism operating in proximity of the PNS surface., Comment: 13 pages, 12 figures; accepted for publication in MNRAS

Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis. However, in Galactic chemical evolution models, neutron-star mergers alone cannot reproduce the observed element abundance patterns of extremely metal-poor stars, which indicates the existence of other sites of r-process nucleosynthesis. These sites may be investigated by studying the element abundance patterns of chemically primitive stars in the halo of the Milky Way, because these objects retain the nucleosynthetic signatures of the earliest generation of stars. Here we report the element abundance pattern of the extremely metal-poor star SMSS J200322.54-114203.3. We observe a large enhancement in r-process elements, with very low overall metallicity. The element abundance pattern is well matched by the yields of a single 25-solar-mass magnetorotational hypernova. Such a hypernova could produce not only the r-process elements, but also light elements during stellar evolution, and iron-peak elements during explosive nuclear burning. Hypernovae are often associated with long-duration gamma-ray bursts in the nearby Universe. This connection indicates that similar explosions of fast-spinning strongly magnetized stars occurred during the earliest epochs of star formation in our Galaxy., Comment: Author's version of a Letter published in Nature on July 8th, 2021

The Cygnus Superbubble (CSB) is a region of soft X-ray emission approximately 13 degrees wide in the direction of the local spiral arm. Such a large region might be the result of strong stellar winds and supernovae from nearby stellar nurseries, or it could be the result of a single event - a hypernova. HaloSat observed 4 non-overlapping 10 degree diameter fields in the CSB region over the 0.4-7 keV band. The CSB absorption and temperature was found to be consistent over all 4 fields, with a weighted average of 6.1x10^21 cm^-2 and 0.190 keV, respectively. These observations suggest that the CSB is a cohesive object with a singular origin. The total thermal energy for the CSB is estimated at 4x10^52 erg, based upon a shell-like physical model of the CSB. Absorption and distance estimates to Cyg OB associations are examined. The CSB absorption is found to be most consistent with the absorption seen in Cyg OB1, implying that the CSB lies at a similar distance of 1.1-1.4 kpc., Comment: 14 pages. 6 figures

The detection of high-energy astrophysical neutrinos and ultra-high-energy cosmic rays (UHECRs) provides a new way to explore sources of cosmic rays. One of the highest energy neutrino events detected by IceCube, tagged as IC35, is close to the UHECR anisotropy region detected by Pierre Auger Observatory. The nearby starburst galaxy (SBG), NGC 4945, is close to this anisotropic region and inside the mean angular error of the IC35 event. Considering the hypernovae contribution located in the SB region of NGC 4945, which can accelerate protons up to $\sim 10^{17} \, {\rm eV}$ and inject them into the interstellar medium, we investigate the origin of this event around this starburst galaxy. We show that the interaction of these protons with the SB region's gas density could explain Fermi-LAT gamma-ray and radio observations if the magnetic field's strength in the SB region is the order of $\sim \rm mG$. Our estimated PeV neutrino events, in ten years, for this source is approximately 0.01 ($4\times10^{-4}$) if a proton spectral index of 2.4 (2.7) is considered, which would demonstrate that IC35 is not produced in the central region of this SBG. Additionally, we consider the superwind region of NGC 4945 and show that protons can hardly be accelerated in it up to UHEs., Accepted in Physical Review D

We present the nucleosynthesis of magneto-rotational supernovae (MR-SNe) including neutrino-driven and magneto-rotational-driven ejecta based, for the first time, on two-dimensional simulations with accurate neutrino transport. The models analysed here have different rotation and magnetic fields, allowing us to explore the impact of these two key ingredients. The accurate neutrino transport of the simulations is critical to analyse the slightly neutron rich and proton rich ejecta that are similar to the, also neutrino-driven, ejecta in standard supernovae. In the model with strong magnetic field, the r-process produces heavy elements up to the third r-process peak (A ∼ 195), in agreement with previous works. This model presents a jet-like explosion with proton-rich jets surrounded by neutron rich material where the r-process occurs. We have estimated a lower limit for 56Ni of 2.5 × 10−2M⊙, which is still well below the expected hypernova value. Longer simulations including the accretion disk evolution are required to get a final prediction. In addition, we have found that the late evolution is critical in a model with weak magnetic field in which lately ejected neutron rich matter produces elements up to the second r-process peak. Even if we cannot yet provide conclusions for hypernova nucleosynthesis, our results agree with observations of old stars and radioactive isotopes in supernova remnants. This makes MR-SNe a good additional scenario to neutron star mergers for the synthesis of heavy elements and brings us closer to understand their origin and the role of MR-SNe in the early galaxy nucleosynthesis.

One-zone models constructed to match observed stellar abundance patterns have been used extensively to constrain the sites of nucleosynthesis with sophisticated libraries of stellar evolution and stellar yields. The metal mixing included in these models is usually highly simplified, although it is likely to be a significant driver of abundance evolution. In this work we use high-resolution hydrodynamics simulations to investigate how metals from individual enrichment events with varying source energies $E_{\rm ej}$ mix throughout the multi-phase interstellar medium (ISM) of a low-mass ($M_{\rm gas}=2\times 10^{6}$~M$_{\odot}$), low-metallicity, isolated dwarf galaxy. These events correspond to the characteristic energies of both common and exotic astrophysical sites of nucleosynthesis, including: asymptotic giant branch winds ($E_{\rm ej}\sim$10$^{46}$~erg), neutron star-neutron star mergers ($E_{\rm ej}\sim$10$^{49}$~erg), supernovae ($E_{\rm ej}\sim$10$^{51}$~erg), and hypernovae ($E_{\rm ej}\sim$10$^{52}$~erg). We find the mixing timescales for individual enrichment sources in our dwarf galaxy to be long (100~Myr--1~Gyr), with a clear trend of increasing homogeneity for the more energetic events. Given these timescales, we conclude that the spatial distribution and frequency of events are important drivers of abundance homogeneity on large scales; rare, low $E_{\rm ej}$ events should be characterized by particularly broad abundance distributions. The source energy $E_{\rm ej}$ also correlates with the fraction of metals ejected in galactic winds, ranging anywhere from 60\% at the lowest energy to 95\% for hypernovae. We conclude by examining how the radial position, local ISM density, and global star formation rate influence these results., Submitted to ApJ. First revision. 17 pages, 12 figures

We investigate the intrinsic scatter in the chemical abundances of a sample of metal-poor ([Fe/H], Comment: 14 pages, 9 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society

Supernova 1986J is almost the same age as SN 1987A, but was Type IIn, and likely had a massive progenitor. Located at 10 Mpc in NGC 891, it is one of the few supernovae whose radio emission can be resolved using VLBI. We present a new 5-GHz global-VLBI image of SN 1986J from 2014 as well as broadband VLA flux-density measurements. SN 1986J is unusual in that a compact synchrotron radio-emitting component appeared in the centre of the expanding shell of ejecta ~14 yr after the explosion, which now dominates the VLBI image. The central component is stationary to within the uncertainties (−1), and it has a marginally resolved HWHM radius of (6.7−3.7+0.7) × 1016cm. The shell has expanded with averagev≃ 5400 km s−1. The central component’s 5-GHz flux density is still increasing with time, and at present it has a 5-GHz νLνluminosity of ~4 × 1035erg s−1, ~20 times that of the Crab Nebula. The central component may be due to a newly formed pulsar wind nebula, or an accreting black hole, or it may be due to interaction of the supernova shock with a highly structured environment left over from a progenitor which was in a close binary system. We discuss the newest observations and the constraints on its nature.

A multi-decade theoretical effort has been devoted to finding an efficient mechanism to use the rotational and electrodynamical extractable energy of a Kerr-Newman black hole (BH), to power the most energetic astrophysical sources such as gamma-ray bursts (GRBs) and active galactic nuclei (AGN). We show an efficient general relativistic electrodynamical process which occurs in the "inner engine" of a binary driven hypernova (BdHN). The {inner engine} is composed of a rotating Kerr BH of mass $M$ and dimensionless spin parameter $\alpha$, a magnetic field of strength $B_0$ aligned and parallel to the rotation axis, and a very low-density ionized plasma. Here, we show that the gravitomagnetic interaction between the BH and the magnetic field induces an electric field that accelerates electrons and protons from the environment to ultrarelativistic energies emitting synchrotron radiation. We show that in GRB 190114C the BH of mass $M = 4.4~M_\odot$, $\alpha= 0.4$, and $B_0 \approx 4\times 10^{10}$ G can lead to a high-energy ($\gtrsim$GeV) luminosity of $10^{51}$ erg s$^{-1}$. The inner engine parameters are determined by requiring 1) that the BH extractable energy explains the GeV and ultrahigh-energy emission energetics, 2) that the emitted photons are not subjected to magnetic-pair production, and 3) that the synchrotron radiation timescale agrees with the observed high-energy timescale. We find for GRB 190114C a clear jetted emission of GeV energies with a semi-aperture angle of approximately $60^\circ$ with respect to the BH rotation axis., Comment: Matches version to appear in A&A

We calculate the mean evolution of the iron-peak abundance ratios [(Cr,Mn,Co,Zn)/Fe] in the Galaxy, using modern supernova and hypernova chemical yields and a Galactic Chemical Evolution code that assumes homogeneous chemical evolution. We investigate a range of hypernova occurrence rates and are able to produce a chemical composition that is a reasonable fit to the observed values in metal-poor stars. This requires a hypernova occurence rate that is large (50%) in the early Universe, decreasing throughout evolution to a value that is within present day observational constraints (>~ 1%). A large hypernova occurence rate is beneficial to matching the high [Zn/Fe] observed in the most metal-poor stars, although including hypernovae with progenitor mass >= 60 solar masses is detrimental to matching the observed [(Mn,Co)/Fe] evolution at low [Fe/H]. A significant contribution from HNe seems to be critical for producing supersolar [(Co,Zn)/Fe] at low metallicity, though more work will need to be done in order to match the most extreme values. We also emphasise the need to update models for the enrichment sources at higher metallicity, as the satisfactory recovery of the solar values of [(Cr,Mn,Co,Zn)/Fe] still presents a challenge., 17 pages, 14 figures

GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from the initial supernova appearance to the final emergence of the optical SN signal. It offers an unprecedented testing ground for the BdHN theory and it is here determined and further extended to additional gamma-ray bursts (GRBs). BdHNe comprise two subclasses of long GRBs with progenitors a binary system composed of a carbon-oxygen star (CO$_\textrm{core}$) and a neutron star (NS) companion. The CO$_\textrm{core}$ explodes as a SN leaving at its center a newborn NS ($\nu$NS). The SN ejecta hypercritically accretes both on the $\nu$NS and the NS companion. BdHNe I are the tightest binaries where the accretion leads the companion NS to gravitational collapse into a black hole (BH). In BdHN II the accretion onto the NS is lower, so there is no BH formation. We observe the same structure of the afterglow for GRB 190114C and other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and for BdHN II (GRB 180728A). In all the cases the explanation of the afterglow is reached via the synchrotron emission powered by the $\nu$NS: their magnetic fields structures and their spin are determined. For BdHNe I, we discuss the properties of the magnetic field embedding the newborn BH, inherited from the collapsed NS and amplified during the gravitational collapse process, and surrounded by the SN ejecta., Comment: 7 figures, 3 tables, submitted to ApJ

International audience; We propose that the "inner engine" of a type I binary-driven hypernova (BdHN) is composed of a Kerr black hole (BH) in a non-stationary state, embedded in a uniform magnetic field $B_0$ aligned with the BH rotation axis, and surrounded by an ionized plasma of extremely low density of $10^{-14}$~g~cm$^{-3}$. Using GRB 130427A as a prototype we show that this "inner engine" acts in a sequence of "elementary impulses". Electrons are accelerated to ultra-relativistic energy near the BH horizon and, propagating along the polar axis, $\theta =0$, they can reach energies of $\sim 10^{18}$ eV, and partially contribute to ultra-high energy cosmic rays (UHECRs). When propagating with ${\theta \neq 0}$ through the magnetic field $B_0$ they give origin by synchrotron emission to GeV and TeV radiation. The mass of BH, $M=2.3 M_\odot$, its spin, $\alpha = 0.47$, and the value of magnetic field $B_0= 3.48 \times 10^{10}$ G, are determined self-consistently in order to fulfill the energetic and the transparency requirement. The repetition time of each elementary impulse of energy ${\cal E} \sim 10^{37}$ erg, is $\sim 10^{-14}$ s at the beginning of the process, then slowly increasing with time evolution. In principle, this "\textit{inner engine}" can operate in a GRB for thousands of years. By scaling the BH mass and the magnetic field the same "inner engine" can describe active galactic nuclei (AGN).

On 2018 July 28, GRB 180728A triggered \textit{Swift} satellites and, soon after the determination of the redshift, we identified this source as a type II binary-driven hypernova (BdHN II) in our model. Consequently, we predicted the appearance time of its associated supernova (SN), which was later confirmed as SN 2018fip. A BdHN II originates in a binary composed of a carbon-oxygen core (CO$_{\rm core}$) undergoing SN, and the SN ejecta hypercritically accrete onto a companion neutron star (NS). From the time of the SN shock breakout to the time when the hypercritical accretion starts, we infer the binary separation $\simeq 3 \times 10^{10}$ cm. The accretion explains the prompt emission of isotropic energy $\simeq 3 \times 10^{51}$ erg, lasting $\sim 10$ s, and the accompanying observed blackbody emission from a thermal convective instability bubble. The new neutron star ($\nu$NS) originating from the SN powers the late afterglow from which a $\nu$NS initial spin of $2.5$ ms is inferred. We compare GRB 180728A with GRB 130427A, a type I binary-driven hypernova (BdHN I) with isotropic energy $> 10^{54}$ erg. For GRB 130427A we have inferred an initially closer binary separation of $\simeq 10^{10}$ cm, implying a higher accretion rate leading to the collapse of the NS companion with consequent black hole formation, and a faster, $1$ ms spinning $\nu$NS. In both cases, the optical spectra of the SNe are similar, and not correlated to the energy of the gamma-ray burst. We present three-dimensional smoothed-particle-hydrodynamic simulations and visualisations of the BdHNe I and II., Comment: 20 pages, 6 figures, 3 tables. Accepted for publication in ApJ

Within the binary-driven hypernova I (BdHN I) scenario, the gamma-ray burst GRB190114C originates in a binary system composed of a massive carbon-oxygen core (CO$_{core}$), and a binary neutron star (NS) companion. As the CO$_{core}$ undergoes a supernova explosion with the creation of a new neutron star ($\nu$NS), hypercritical accretion occurs onto the companion binary neutron star until it exceeds the critical mass for gravitational collapse. The formation of a black hole (BH) captures $10^{57}$ baryons by enclosing them within its horizon, and thus a cavity of approximately $10^{11}$ cm is formed around it with initial density $10^{-7}$ g/cm$^3$. A further depletion of baryons in the cavity originates from the expansion of the electron-positron-photon ($e^{+}e^{-}\gamma$) plasma formed at the collapse, reaching a density of $10^{-14}$ g/cm$^3$ by the end of the interaction. It is demonstrated here using an analytical model complemented by a hydrodynamical numerical simulation that part of the $e^{+}e^{-}\gamma$ plasma is reflected off the walls of the cavity. The consequent outflow and its observed properties are shown to coincide with the featureless emission occurring in a time interval of duration $t_{rf}$, measured in the rest frame of the source, between $11$ and $20$ s of the GBM observation. Moreover, similar features of the GRB light curve were previously observed in GRB 090926A and GRB 130427A, all belonging to the BdHN I class. This interpretation supports the general conceptual framework presented in Ruffini et al. (2019) and guarantees that a low baryon density is reached in the cavity, a necessary condition for the operation of the "inner engine" of the GRB presented in an accompanying article (Ruffini & Moradi 2019).

In this book, we performed a series of N-body/smoothed particle hydrodynamics simulations of dwarf galaxies to clarify the enrichment of heavy elements. This book aims to understand (1) the contribution of neutron star mergers and supernovae (core-collapse supernovae, hypernovae, electron-capture supernovae, and type Ia supernovae) to the enrichment of heavy elements and (2) the relation between the chemodynamical evolution of galaxies and the abundances of heavy elements. Here we show the new findings in this book.

The N-body/hydrodynamic simulations are powerful tools to conduct the study of the formation and evolution of galaxies. Several different groups have been developed codes for simulating galaxy formation. Here we describe the N-body and smoothed particle hydrodynamics (SPH) code, asura. Simulations of galaxy formation cannot resolve each star. We thus implement star formation and supernova feedback recipes in a simple stellar population approximation. We put the effects of iron-core collapse supernovae, hypernovae, electron-capture supernovae, neutron star mergers, type Ia supernovae, and asymptotic giant branch stars into the code. In this chapter, we also describe metal mixing models for SPH simulations [Contents in this chapter have been in part published in Hirai et al. (Astrophys J 814:41, 2015 [29]), (Astrophys J 855:63, 2018 [30]) reproduced by permission of the AAS].

This chapter aims to clarify the role of supernovae (core-collapse supernovae, electron-capture supernovae, hypernovae, and type Ia supernovae) to the chemical evolution of galaxies. We focus on the enrichment of Zn in this chapter. Zn is the heaviest iron-peak element and has been used as a tracer of metallicity in damped Lyman-\(\alpha \) systems. High-resolution spectroscopic observations have shown that there is a decreasing trend of [Zn/Fe] toward higher metallicity. However, the astrophysical sites and the enrichment of Zn are not well understood. In this chapter, we show that electron-capture supernovae can contribute to the enrichment of Zn at low metallicity. We find that stars which have [Zn/Fe] \(\gtrsim \) 0.5 are formed from the ejecta of electron-capture supernovae. At higher metallicity, type Ia supernovae make scatters of [Zn/Fe] ratios. We also find that it is difficult to reproduce observations of [Zn/Fe] ratios without considering the effects of electron-capture supernovae or low mass iron core-collapse supernovae. These results suggest that supernovae from the lowest mass ranges can be one of the main astrophysical sites of Zn [(Contents in this chapter have been published in Hirai et al. (Astrophys J 855:63, 2018 [9]) reproduced under the terms of Creative Commons Attribution 3.0 license (https://creativecommons.org/licenses/by/3.0/))].

We propose that the "inner engine" of a type I binary-driven hypernova (BdHN) is composed of a Kerr black hole (BH) in a non-stationary state, embedded in a uniform magnetic field $B_0$ aligned with the BH rotation axis, and surrounded by an ionized plasma of extremely low density of $10^{-14}$~g~cm$^{-3}$. Using GRB 130427A as a prototype we show that this "inner engine" acts in a sequence of "elementary impulses". Electrons are accelerated to ultra-relativistic energy near the BH horizon and, propagating along the polar axis, $\theta =0$, they can reach energies of $\sim 10^{18}$ eV, and partially contribute to ultra-high energy cosmic rays (UHECRs). When propagating with ${\theta \neq 0}$ through the magnetic field $B_0$ they give origin by synchrotron emission to GeV and TeV radiation. The mass of BH, $M=2.3 M_\odot$, its spin, $\alpha = 0.47$, and the value of magnetic field $B_0= 3.48 \times 10^{10}$ G, are determined self-consistently in order to fulfill the energetic and the transparency requirement. The repetition time of each elementary impulse of energy ${\cal E} \sim 10^{37}$ erg, is $\sim 10^{-14}$ s at the beginning of the process, then slowly increasing with time evolution. In principle, this "\textit{inner engine}" can operate in a GRB for thousands of years. By scaling the BH mass and the magnetic field the same "inner engine" can describe active galactic nuclei (AGN)., Comment: Matches version to be published by The Astrophysical Journal on 22 November 2019

Pop III stars are typically massive stars of primordial composition forming at the centers of the first collapsed dark matter structures. Here we estimate the optimal X-ray emission in the early universe for promoting the formation of Pop III stars. This is important in determining the number of dwarf galaxies formed before reionization and their fossils in the local universe, as well as the number of intermediate-mass seed black holes. A mean X-ray emission per source above the optimal level reduces the number of Pop III stars because of the increased Jeans mass of the intergalactic medium (IGM), while a lower emission suppresses the formation rate of H2 preventing or delaying star formation in dark matter minihalos above the Jeans mass. The build up of the H2 dissociating background is slower than the X-ray background due to the shielding effect of resonant hydrogen Lyman lines. Hence, the nearly unavoidable X-ray emission from supernova remnants of Pop III stars is sufficient to boost their number to few tens per comoving Mpc^3 by redshift z~15. We find that there is a critical X-ray to UV energy ratio emitted per source that produces a universe where the number of Pop III stars is largest: 400 per comoving- Mpc^3. This critical ratio is very close to the one provided by 20-40 M_sun Pop III stars exploding as hypernovae. High mass X-ray binaries in dwarf galaxies are far less effective at increasing the number of Pop III stars than normal supernova remnants, we thus conclude that supernovae drove the formation of Pop III stars.

To reach a deeper understanding of the origin of elements in the periodic table, we construct Galactic chemical evolution (GCE) models for all stable elements from C (A = 12) to U (A = 238) from first principles, i.e., using theoretical nucleosynthesis yields and event rates of all chemical enrichment sources. This enables us to predict the origin of elements as a function of time and environment. In the solar neighborhood, we find that stars with initial masses of M > 30M ⊙ can become failed supernovae if there is a significant contribution from hypernovae (HNe) at M ∼ 20–50M ⊙. The contribution to GCE from super-asymptotic giant branch (AGB) stars (with M ∼ 8–10M ⊙ at solar metallicity) is negligible, unless hybrid white dwarfs from low-mass super-AGB stars explode as so-called Type Iax supernovae, or high-mass super-AGB stars explode as electron-capture supernovae (ECSNe). Among neutron-capture elements, the observed abundances of the second (Ba) and third (Pb) peak elements are well reproduced with our updated yields of the slow neutron-capture process (s-process) from AGB stars. The first peak elements (Sr, Y, Zr) are sufficiently produced by ECSNe together with AGB stars. Neutron star mergers can produce rapid neutron-capture process (r-process) elements up to Th and U, but the timescales are too long to explain observations at low metallicities. The observed evolutionary trends, such as for Eu, can well be explained if ∼3% of 25–50M ⊙ HNe are magneto-rotational supernovae producing r-process elements. Along with the solar neighborhood, we also predict the evolutionary trends in the halo, bulge, and thick disk for future comparison with Galactic archeology surveys.

Similar to star-forming galaxies or starburst galaxies, star-forming regions in our Galaxy can host cosmic-ray (CR) accelerators and rich gas as targets of hadronuclear interaction. By our estimations, the IceCube neutrino observatory might detect muon neutrinos from a CR accelerator associated with a molecular cloud complex in our Galaxy. The associated high-energy gamma-ray emission might be observed by the Cherenkov Telescope Array (CTA), High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC), and Large High Altitude Air Shower Observatory (LHAASO). Furthermore, taking the Galactic Center (GC) region as an example, we assume that a hypernova exploded in the past in the GC. We simulate the acceleration of CRs in the hypernova remnant (HNR) as well as their confinement and escape. The high-energy protons escape from the HNR, diffuse around the GC, interact with molecular clouds, and then produce gamma-rays and neutrinos. In the optimal cases, the GC would be a promising 100 TeV gamma-ray source for LHAASO’s one-month observation. We propose that neutrino-induced searching for starting track-like and high-energy starting events (HESEs) observed by IceCube, from the GC region with a radius of 1.°8, would help us discover the particle accelerator in the GC or constrain our models. Under the constraint from high-energy gamma-ray observations by the H.E.S.S. telescope, we estimate the exposure time needed to make a significant discovery for the optimal cases. The analysis combining observations of IceCube and ANTARES, starting track-like events and HESEs, future observations by neutrino detectors IceCube-Gen2 and KM3net, and gamma-ray telescopes CTA, HAWC, and LHAASO would help to constrain our models.

Using high-resolution simulations from the FIRE-2 (Feedback In Realistic Environments) project, we study the effects of discreteness in stellar feedback processes on the evolution of galaxies and the properties of the interstellar medium (ISM). We specifically consider the discretization of supernovae (SNe), including hypernovae (HNe), and sampling the initial mass function (IMF). We study these processes in cosmological simulations of dwarf galaxies with $z=0$ stellar masses $M_{\ast}\sim 10^{4}-3\times10^{6}\,M_\odot$ (halo masses $\sim 10^{9}-10^{10}\,M_\odot$). We show that the discrete nature of individual SNe (as opposed to a model in which their energy/momentum deposition is continuous over time, similar to stellar winds) is crucial in generating a reasonable ISM structure and galactic winds and in regulating dwarf stellar masses. However, once SNe are discretized, accounting for the effects of IMF sampling on continuous mechanisms such as radiative feedback and stellar mass-loss (as opposed to adopting IMF-averaged rates) has weak effects on galaxy-scale properties. We also consider the effects of rare HNe events with energies $\sim 10^{53}\,{\rm erg}$. The effects of HNe are similar to the effects of clustered explosions of SNe -- which are already captured in our default simulation setup -- and do not quench star formation (provided that the HNe do not dominate the total SNe energy budget), which suggests that HNe yield products should be observable in ultra-faint dwarfs today., Comment: 9 pages, 4 figures

We study how the predicted [$\alpha$/Fe]-[Fe/H] relations in early-type galaxies vary as functions of their stellar masses, ages and stellar velocity dispersions, by making use of cosmological chemodynamical simulations with feedback from active galactic nuclei. Our model includes a detailed treatment for the chemical enrichment from dying stars, core-collapse supernovae (both Type II and hypernovae) and Type Ia supernovae. At redshift $z=0$, we create a catalogue of $526$ galaxies, among which we determine $80$ early-type galaxies. From the analysis of our simulations, we find [$\alpha$/Fe]-[Fe/H] relations similar to the Galactic bulge. We also find that, in the oldest galaxies, Type Ia supernovae start to contribute at higher [Fe/H] than in the youngest ones. On the average, early-type galaxies with larger stellar masses (and, equivalently, higher stellar velocity dispersions) have higher [$\alpha$/Fe] ratios, at fixed [Fe/H]. This is qualitatively consistent with the recent observations of Sybilska et al., but quantitatively there are mismatches, which might require stronger feedback, sub-classes of Type Ia Supernovae, or a variable initial mass function to address., Comment: Accepted for publication in MNRAS Letters

Oxygen and zinc in the Galactic bulge are key elements for the understanding of the bulge chemical evolution. Oxygen-to-iron abundance ratios provide a most robust indicator of the star formation rate and chemical evolution of the bulge. Zinc is enhanced in metal-poor stars, behaving as an $\alpha$-element, and its production may require nucleosynthesis in hypernovae. Most of the neutral gas at high redshift is in damped Lyman-alpha systems (DLAs), where Zn is also observed to behave as an alpha-element. The aim of this work is the derivation of the alpha-element oxygen, together with nitrogen, and the iron-peak element zinc abundances in 417 bulge giants, from moderate resolution (R~22,000) FLAMES-GIRAFFE spectra. For stars in common with a set of UVES spectra with higher resolution (R~45,000), the data are intercompared. The results are compared with literature data and chemodynamical models., Comment: accepted on 21/02/2018

We have serendipitously discovered that Leoncino Dwarf, an ultra-faint, low-metallicity record-holder dwarf galaxy, may have hosted a transient source, and possibly exhibited a change in morphology, a shift in the center of brightness, and peak variability of the main (host) source in images taken approximately 40 yr apart; it is highly likely that these phenomena are related. Scenarios involving a Solar System object, a stellar cluster, dust enshrouding, and accretion variability have been considered, and discarded, as the origin of the transient. Although a combination of time-varying strong and weak lensing effects, induced by an intermediate mass black hole (10$^4$ - 5 $\times$ 10$^{5}$ M$_{\odot}$) moving within the Milky Way halo (0.1 -- 4 kpc), can conceivably explain all of the observed variable galaxy properties, it is statistically highly unlikely according to current theoretical predictions, and, therefore, also discarded. A cataclysmic event such as a supernova/hypernova could have occurred, as long as the event was observed towards the later/late-stage descent of the light curve, but this scenario fails to explain the absence of a post-explosion source and/or host HII region in recent optical images. An episode related to the giant eruption of a luminous blue variable star, a stellar merger or a nova, observed at, or near, peak magnitude may explain the transient source and possibly the change in morphology/center of brightness, but can not justify the main source peak variability, unless stellar variability is evoked.

Recent results from the Pierre Auger Collaboration have shown that the composition of ultrahigh-energy cosmic rays (UHECRs) becomes gradually heavier with increasing energy. Although gamma-ray bursts (GRBs) have been promising sources of UHECRs, it is still unclear whether they can account for the Auger results because of their unknown nuclear composition of ejected UHECRs. In this work, we revisit the possibility that low-luminosity GRBs (LL GRBs) act as the sources of UHECR nuclei, and give new predictions based on the intrajet nuclear composition models considering progenitor dependencies. We find that the nuclear component in the jet can be divided into two groups according to the mass fraction of silicon nuclei, Si-free and Si-rich. Motivated by the connection between LL GRBs and transrelativistic supernovae, we also consider the hypernova ejecta composition. Then, we discuss the survivability of UHECR nuclei in the jet base and internal shocks of the jets, and show that it is easier for nuclei to survive for typical LL GRBs. Finally, we numerically propagate UHECR nuclei ejected from LL GRBs with different composition models and compare the resulting spectra and composition to Auger data. Our results show that both the Si-rich progenitor and hypernova ejecta models match the Auger data well, while the Si-free progenitor models have more difficulty in fitting the spectrum. We argue that our model is consistent with the newly reported cross correlation between the UHECRs and starburst galaxies, since both LL GRBs and hypernovae are expected to be tracers of the star-formation activity. LL GRBs have also been suggested as the dominant origin of IceCube neutrinos in the PeV range, and the LL GRB origin of UHECRs can be critically tested by near-future multimessenger observations., 17 pages, 16 figures, minor corrections, added the discussion about the possible correlation with starburst galaxies, version accepted by PRD

We present the status and open problems of nucleosynthesis in supernova explosions of both types, responsible for the production of the intermediate mass, Fe-group and heavier elements (with the exception of the main s-process). Constraints from observations can be provided through individual supernovae (SNe) or their remnants (e.g. via spectra and gamma-rays of decaying unstable isotopes) and through surface abundances of stars which witness the composition of the interstellar gas at their formation. With a changing fraction of elements heavier than He in these stars (known as metallicity) the evolution of the nucleosynthesis in galaxies over time can be determined. A complementary way, related to gamma-rays from radioactive decays, is the observation of positrons released in $\beta^{+}$ -decays, as e.g. from $^{26}\mbox{Al}$ , $^{44}\mbox{Ti}$ , $^{56,57}\mbox{Ni}$ and possibly further isotopes of their decay chains (in competition with the production of $e^{+}e^{-}$ pairs in acceleration shocks from SN remnants, pulsars, magnetars or even of particle physics origin). We discuss (a) the role of the core-collapse supernova explosion mechanism for the composition of intermediate mass, Fe-group (and heavier?) ejecta, (b) the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, faint supernovae, and gamma-ray bursts/hypernovae, (c) Type Ia supernovae and their nucleosynthesis (e.g. addressing the $^{55}\mbox{Mn}$ puzzle), plus (d) further constraints from galactic evolution, $\gamma$ -ray and positron observations. This is complemented by the role of rare magneto-rotational supernovae (related to magnetars) in comparison with the nucleosynthesis of compact binary mergers, especially with respect to forming the heaviest r-process elements in galactic evolution.

Different types of core-collapse supernovae (SNe) have been considered as candidate sources of high-energy cosmic neutrinos. Stripped-envelope SNe, including energetic events like hypernovae and super-luminous SNe, are of particular interest. They may harbor relativistic jets, which are capable of explaining the diversity among gamma-ray bursts (GRBs), low-luminosity GRBs, ultra-long GRBs, and broadline Type Ib/c SNe. Using the six-year IceCube data on high-energy starting events (HESEs), we perform an unbinned maximum likelihood analysis to search for spatial and temporal coincidences with 222 samples of SNe Ib/c. We find that the present data are consistent with the background only hypothesis, by which we place new upper constraints on the isotropic-equivalent energy of cosmic rays, ${\mathcal E}_{\rm cr}\lesssim{10}^{52}~{\rm erg}$, in the limit that all SNe are accompanied by on-axis jets. Our results demonstrate that not only upgoing muon neutrinos but also HESE data enable us to constrain the potential contribution of these SNe to the diffuse neutrino flux observed in IceCube. We also discuss implications for the next-generation neutrino detectors such as IceCube-Gen2., Comment: 18 pages, 7 figures; v2: a few clarifications and references added, matches the version published in JCAP

On the ground of the large number of gamma-ray bursts (GRBs) detected with cosmological redshift, we classified GRBs in seven subclasses, all with binary progenitors originating gravitational waves (GWs). Each binary is composed by combinations of carbon-oxygen cores (CO$_{\rm core}$), neutron stars (NSs), black holes (BHs) and white dwarfs (WDs). The long bursts, traditionally assumed to originate from a BH with an ultra-relativistic jetted emission, not emitting GWs, have been subclassified as (I) X-ray flashes (XRFs), (II) binary-driven hypernovae (BdHNe), and (III) BH-supernovae (BH-SNe). They are framed within the induced gravitational collapse (IGC) paradigm with progenitor a CO$_{\rm core}$-NS/BH binary. The supernova (SN) explosion of the CO$_{\rm core}$ triggers an accretion process onto the NS/BH. If the accretion does not lead the NS to its critical mass, an XRF occurs, while when the BH is present or formed by accretion, a BdHN occurs. When the binaries are not disrupted, XRFs lead to NS-NS and BdHNe lead to NS-BH. The short bursts, originating in NS-NS, are subclassified as (IV) short gamma-ray flashes (S-GRFs) and (V) short GRBs (S-GRBs), the latter when a BH is formed. There are (VI) ultra-short GRBs (U-GRBs) and (VII) gamma-ray flashes (GRFs), respectively formed in NS-BH and NS-WD. We use the occurrence rate and GW emission of these subclasses to assess their detectability by Advanced LIGO-Virgo, eLISA, and resonant bars. We discuss the consequences of our results in view of the announcement of the LIGO-Virgo Collaboration of the source GW 170817 as being originated by a NS-NS., Accepted for publication in The Astrophysical Journal

We describe the afterglows of the long gamma-ray-burst (GRB) 130427A within the context of a binary-driven hypernova (BdHN). The afterglows originate from the interaction between a newly born neutron star ($\nu$NS), created by an Ic supernova (SN), and a mildly relativistic ejecta of a hypernova (HN). Such a HN in turn results from the impact of the GRB on the original SN Ic. The mildly relativistic expansion velocity of the afterglow ($\Gamma \sim 3$) is determined, using our model independent approach, from the thermal emission between $196$~s 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 $\nu$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 $5.18\times 10^6$~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 $\nu$NS, for which we adopt an initial rotation period of $2$~ms and a dipole plus quadrupole magnetic field of $\lesssim \! 7\times 10^{12}$~G or $\sim \! 10^{14}$~G. This scenario with a progenitor composed of a CO$_{\rm core}$ and a NS companion differs from the traditional ultra-relativistic-jetted treatments of the afterglows originating from a single black hole., Comment: Accepted by ApJ on October 21st, 2018

We analyze the early X-ray flares in the GRB "flare-plateau-afterglow" (FPA) phase observed by Swift-XRT. The FPA occurs only in one of the seven GRB subclasses: the binary-driven hypernovae (BdHNe). This subclass consists of long GRBs with a carbon-oxygen core and a neutron star (NS) binary companion as progenitors. The hypercritical accretion of the supernova (SN) ejecta onto the NS can lead to the gravitational collapse of the NS into a black hole. Consequently, one can observe a GRB emission with isotropic energy $E_{iso}\gtrsim10^{52}$~erg, as well as the associated GeV emission and the FPA phase. Previous work had shown that gamma-ray spikes in the prompt emission occur at $\sim 10^{15}$--$10^{17}$~cm with Lorentz gamma factor $\Gamma\sim10^{2}$--$10^{3}$. Using a novel data analysis we show that the time of occurrence, duration, luminosity and total energy of the X-ray flares correlate with $E_{iso}$. A crucial feature is the observation of thermal emission in the X-ray flares that we show occurs at radii $\sim10^{12}$~cm with $\Gamma\lesssim 4$. These model independent observations cannot be explained by the "fireball" model, which postulates synchrotron and inverse Compton radiation from a single ultra relativistic jetted emission extending from the prompt to the late afterglow and GeV emission phases. We show that in BdHNe a collision between the GRB and the SN ejecta occurs at $\simeq10^{10}$~cm reaching transparency at $\sim10^{12}$~cm with $\Gamma\lesssim4$. The agreement between the thermal emission observations and these theoretically derived values validates our model and opens the possibility of testing each BdHN episode with the corresponding Lorentz gamma factor., Comment: 57 pages, 40 figures, accepted for publication on ApJ

We investigate the relationship between explosion energy and nucleosynthesis in Population III supernovae and provide nucleosynthetic results for the explosions of stars with progenitor masses of $15\,\mathrm{M}_\odot$, $20\,\mathrm{M}_\odot$, $30\,\mathrm{M}_\odot$, $40\,\mathrm{M}_\odot$, $60\,\mathrm{M}_\odot$, and $80\,\mathrm{M}_\odot$, and explosion energies between approximately $10^{50}$ erg and $10^{53}$ erg. We find that the typical abundance pattern observed in metal-poor stars are best matched by supernovae with progenitor mass in the range $15\,\mathrm{M}_\odot$ - $30\,\mathrm{M}_\odot$, and explosion energy of $\sim$ ($5$ - $10$) $\times$ $10^{51}$ erg. In these models, a reverse shock caused by jumps in density between shells of different composition serves to decrease synthesis of chromium and manganese, which is favourable to matching the observed abundances in metal-poor stars. Spherically symmetric explosions of our models with progenitor mass $\geq$ $40\,\mathrm{M}_\odot$ do not provide yields that are compatible with the iron-peak abundances that are typically observed in metal-poor stars, however, by approximating the yields that we might expect from these models in highly aspherical explosions, we find indications that explosions of stars $40\,\mathrm{M}_\odot$ - $80\,\mathrm{M}_\odot$ with bipolar jets may be good candidates for the enrichment sources of metal-poor stars with enhanced carbon abundances.

Globular clusters are tracers of the history of star formation and chemical enrichment in the early Galaxy. Their abundance pattern can help understanding their chemical enrichment processes. In particular, the iron-peak elements have been relatively little studied so far in the Galactic bulge. The abundances of iron-peak elements are derived for the sample clusters, and compared with bulge field, and thick disk stars. We derive abundances of the iron-peak elements Sc, V, Mn, Cu, and Zn in individual stars of five bulge globular clusters (NGC 6528, NGC 6553, NGC 6522, NGC 6558, HP1), and of the reference thick disk/inner halo cluster 47 Tucanae (NGC 104). High resolution spectra were obtained with the UVES spectrograph at the Very Large Telescope over the years. The sample globular clusters studied span metallicities in the range -1.2, Comment: article resubmitted to Astronomy & Astrophysics, taking into account referee's comments

The synthesis of Li7 and B11 confronts astrophysicists. Type II (SN II) and Type Ic (SN Ic) supernovae are supposed to be the producers of these two elements. In this study we calculate the yields of these two elements for SN II progenitors with 8, 10 and 20 solar masses. The process considered here is the neutral current interaction of heavy flavour neutrinos (ν μ or ν τ ) with He4 nuclei of the helium zone. The low mass progenitors are considered because the helium zone lies much closer to the core and hence experiences large neutrino flux. The starting point of the helium zone depends on detail stellar model. However, the shell radius at which it begins is available for these stars. 20 solar mass is considered for comparison of our production ratio Li/B with that of an earlier work. It is contrasted with the shock heating yields in the hydrogen envelope. The Li/B ratio has been found to be about 0.96. In the three model stars, the Li7 and B11 yields are found to be in the range 6.61×10−6−2.63×10−6 M Sun and 6.92×10−6−2.75×10−6 M Sun respectively as we go from 8 to 20M Sun. Some equivalence is found with shock induced nucleosynthesis model for SN II. The SN II yield is found to be compatible with that of hypernovae produced by C–O core collapse but higher than the yields obtained by neutrino processes in SNIc.

The induced gravitational collapse (IGC) paradigm addresses energetic (1052-1054 erg), long gamma-ray bursts (GRBs) associated to supernovae (SNe) and proposes as their progenitors tight binary systems composed of an evolved FeCO core and a companion neutron star (NS). Their emission is characterized by four specific episodes: Episode 1, corresponding to the on-set of the FeCO SN explosion and the accretion of the ejecta onto the companion NS; Episode 2, related the collapse of the companionNS to a black hole (BH) and to the emission of a long GRB; Episode 3, observed in X-rays and characterized by a steep decay, a plateau phase and a late power-law decay; Episode 4, corresponding to the optical SN emission due to the 56Ni decay. We focus on Episode 3 and we show that, from the thermal component observed during the steep decay of the prototype GRB 090618, the emission region has a typical dimension of ~1013 cm, which is inconsistent with the typical size of the emitting region of GRBs, e.g., ~1016 cm. We propose, therefore, that the X-ray afterglow emission originates from a spherically symmetric SN ejecta expanding at G ˜ 2 or, possibly, from the accretion onto the newly formed black hole, and we name these systems “binary driven hypernovae” (BdHNe). This interpretation is alternative to the traditional afterglow model based on the GRB synchrotron emission from a collimated jet outflow, expanding at ultra-relativistic Lorentz factor of G ~ 102-103 and originating from the collapse of a single object. We show then that the rest-frame energy band 0.3-10 keV X-ray luminosities of three selected BdHNe, GRB 060729, GRB 061121, and GRB 130427A, evidence a precisely constrained “nested” structure and satisfy precise scaling laws between the average prompt luminosity, 〈Liso〉, and the luminosity at the end of the plateau, La, as functions of the time at the end of the plateau. All these features extend the applicability of the “cosmic candle” nature of Episode 3. The relevance of r-process in fulfilling the demanding scaling laws and the nested structure are indicated.

After the big bang, production of heavy elements in the early universe takes place starting from the formation of the first (Pop III) stars, their evolution, and explosion. The Pop III supernova (SN) explosions have strong dynamical, thermal, and chemical feedback on the formation of subsequent stars and evolution of galaxies. However, the nature of Pop III stars/supernovae (SNe) have not been well-understood. The signature of nucleosynthesis yields of the first SN can be seen in the elemental abundance patterns observed in extremely metal-poor (EMP) stars. We show that the abundance patterns of EMP stars, e.g. the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, (HNe)) rather than normal supernovae. We note the large variation of the abundance patterns of EMP stars propose that such a variation is related to the diversity of the GRB-SNe and posssibly superluminous supernovae (SLSNe). For example, the carbon-enhanced metal-poor (CEMP) stars may be related to the faint SNe (or dark HNe), which could be the explosions induced by relativistic jets. Finally, we examine the various mechanisms of SLSNe.