The behavior of the dark energy equation of state (EOS) is crucial in distinguishing different cosmological models. With a model independent approach, we constrain the possible evolution of the dark energy EOS. Gamma-ray bursts (GRBs) of redshifts up to $z>6$ are used, in addition to type Ia supernovae (SNe Ia). We separate the redshifts into 4 bins and assume a constant EOS parameter for dark energy in each bin. The EOS parameters are decorrelated by diagonalizing the covariance matrix. And the evolution of dark energy is estimated out of the uncorrelated EOS parameters. By including GRB luminosity data, we significantly reduce the confidence interval of the uncorrelated EOS parameter whose contribution mostly comes from the redshift bin of $0.5<z<1.8$. At high redshift where we only have GRBs, the constraints on the dark energy EOS are still very weak. However, we can see an obvious cut at about zero in the probability plot of the EOS parameter, from which we can infer that the ratio of dark energy to matter most probably continues to decrease beyond redshift 1.8. We carried out analyses with and without including the latest BAO measurements, which themselves favor a dark energy EOS of $w<-1$. If they are included, the results show some evidence of an evolving dark energy EOS. If not included, however, the results are consistent with the cosmological constant within $1 σ$ for redshift $0<z \lesssim 0.5$ and $2 σ$ for $0.5 \lesssim z<1.8$.
We use a rigorous method, based on Bayesian inference, for calculating the odds favoring the hypothesis that any particular class of astronomical transients produce gamma-ray bursts over the hypothesis that they do not. We then apply this method to a sample of 83 Type Ia supernovae and a sample of 20 Type Ib-Ic supernovae. We find overwhelming odds against the hypothesis that all Type Ia supernovae produce gamma-ray bursts, whether at low redshift ($10^{9}:1$) or high-redshift ($10^{12}:1$), and very large odds ($6000:1$) against the hypothesis that all Type Ib, Ib/c, and Ic supernovae produce…
Photometry data were collected from the literature and analyzed for supernovae that are thought to have a gamma-ray burst association. There are several gamma-ray burst afterglow light curves that appear to have a supernova component. For these light curves, the supernova component was extracted and analyzed. A supernova light curve model was used to help determine the peak absolute magnitudes as well as estimates for the kinetic energy, ejected mass and nickel mass in the explosion. The peak absolute magnitudes are, on average, brighter than those of similar supernovae (stripped-envelope supe…
The recent discovery of a supernova (SN 1998bw) seemingly associated with GRB~980425 adds a new twist to the decades-old debate over the origin of gamma-ray bursts. To investigate the possibility that some (or all) bursts are associated with supernovae, we performed a systematic search for temporal/angular correlations using catalogs of BATSE and BATSE/{\it Ulysses} burst locations. We find no associations with any of the precise BATSE/{\it Ulysses} locations, which allows us to conclude that the fraction of high-fluence gamma-ray bursts from known supernovae is small ($<$0.2%). For the more n…
We analyse the constraints that can be placed on a cosmological constant or quintessence-like component by combining observations of Type Ia supernovae with measurements of anisotropies in the cosmic microwave background. We use the recent supernovae sample of Perlmutter et al and observations of the CMB anisotropies to constraint the equation of state (w_Q = p/rho) in quintessence-like models via a likelihood analysis. The 2 sigma upper limits are w_Q < -0.6 if the Universe is assumed to be spatially flat, and w_Q < -0.4 for universes of arbitrary spatial curvature. The upper limit derived fo…
Supernovae (SNe) were long suspected as possible progenitors of gamma-ray bursts (GRBs). The arguments relied on circumstantial evidence. Several recent GRBs, notably GRB 030329, have provided direct, spectroscopic evidence that SNe and GRBs are related. The SNe associated with GRBs are all of Type Ic, implying a compact progenitor, which has implications for GRB models. Other peculiar Type Ic SNe may help to expand understanding of the mechanisms involved.
We present a rigorous method, based on Bayesian inference, for calculating the odds favoring the hypothesis that any particular class of astronomical transients produce gamma-ray bursts over the hypothesis that they do not. We then apply this method to a sample of 83 Type Ia supernovae and a sample of 20 Type Ib-Ic supernovae. We find overwhelming odds against the hypothesis that all Type Ia supernovae produce gamma-ray bursts, whether at low redshift ($10^{9}:1$) or high-redshift ($10^{12}:1$), and very large odds ($6000:1$) against the hypothesis that all Type Ib, Ib/c, and Ic supernovae pro…
Current understanding of core collapse and thermonuclear supernovae is reviewed. Recent progress in unveiling the nature of cosmic gamma-ray bursts (GRB) is discussed, with the focus on the apparent link of several GRBs with an energetic subclass of stellar explosions, type Ib/c core-collapse supernovae. This relation provides the strong case that the GRB phenomenon is connected with the final stages of massive star evolution and possibly with the formation of neutron stars and black holes.
Gamma-ray bursts, discovered over three decades ago, can appear to be a hundred times as luminous as the brightest supernovae. However, there has been evidence for some time now of an association of gamma-ray bursts with supernovae of type Ib and Ic. Here we interpret the overabundance of millisecond pulsars in globular clusters and the details of supernova 1987A to reveal the energy source, which powers at least some long-duration gamma-ray bursts, as core-collapse following the merger of two white dwarfs, either as stars or stellar cores. In order for the beams/jets associated with gamma-ray…
When gamma-rays emerge from a central source they may undergo Compton scattering in surrounding matter. The resulting Compton-scattered electrons radiate. Coherent radiation by such Compton electrons follows nuclear explosions above the Earth's atmosphere. Particle acceleration in instabilities produced by Compton electron currents may explain the radio emission by SN1998bw. Bounds on coherent radiation are suggested for supernovae and gamma-ray bursts; these bounds are very high, but it is unknown if coherent radiation occurs in these objects.
The last five years have seen growing challenges to the traditional paradigm of a core collapse supernova powered by the neutrino emission of a young proto-neutron star. Chief among these challenges are gamma-ray bursts (GRBs) and the supernovae that seem to accompany them. Here we review some recent - and not so recent - models for GRBs and supernovae in which strong magnetic fields, rotation, or accretion into a black hole play a role. The conditions for these energetic explosions are special and, at this point, there is no compelling reason to invoke them in the general case. That is, 99% o…
We explore the gamma-ray bursts' (GRBs') contributions in constraining the dark energy equation of state (EOS) at high ($1.8 < z < 7$) and at middle redshifts ($0.5 < z < 1.8$) and estimate how many GRBs are needed to get substantial constraints at high redshifts. We estimate the constraints with mock GRBs and mock type Ia supernovae (SNe Ia) for comparisons. When constraining the dark energy EOS in a certain redshift range, we allow the dark energy EOS parameter to vary only in that redshift bin and fix EOS parameters elsewhere to -1. We find that it is difficult to constrain the dark energy …
The currently-favored model for long-duration gamma-ray bursts (GRBs) invokes explosions from the collapse of a massive star down to a black hole: either directly or through fallback. Those GRBs forming via fallback will produce much less radioactive nickel, and hence it has been argued (without any real calculation) that these systems produce dim supernovae. These fallback black-hole GRBs have been recently been argued as possible progenitors of a newly discovered set of GRBs lacking any associated supernovae. Here we present the first ever radiation-hydrodynamics calculations of the light-cu…
A two-component fluid representing dark energy is studied. One of the components has a polytropic form, while the other has a barotropic form. Exact solutions are obtained and the cosmological parameters are constrained using supernova type Ia data. In general, an open universe is predicted. A big rip scenario is largely preferred, but the dispersion in the parameter space is very high. Hence, even if scenarios without future singularities can not be excluded with the allowed range of parameters, a phantom cosmology, with an open spatial section, is a general prediction of the model. For a wid…
We explore the hypothesis, similar to one recently suggested by Bloom and colleagues, that some nearby supernovae are associated with smooth, single-pulse gamma-ray bursts, possibly having no emission above ~ 300 keV. We examine BATSE bursts with durations longer than 2 s, fitting those which can be visually characterized as single-pulse events with a lognormal pulse model. The fraction of events that can be reliably ascertained to be temporally and spectrally similar to the exemplar, GRB 980425 - possibly associated with SN 1998bw - is 4/1573 or 0.25%. This fraction could be as high as 8/1573…
We review the effects of winds from massive O and B stars on the surrounding medium over the various stages of stellar evolution. Furthermore we discuss some of the implications for SNe and GRB evolution within this wind-blown medium.
Gamma-ray bursts can appear to be a hundred times as luminous as supernovae, but their underlying energy source(s) have remained a mystery. However, there has been evidence for some time now of an association of gamma-ray bursts with supernovae of Type Ib and Ic, a fact which has been exploited by a number of models, to explain the gamma-ray burst phenomenon. Here we interpret the results of basic observations of SN 1987A and of pulsars in globular clusters, to propose the energy source, which powers at least some long-duration gamma-ray bursts, as core-collapse following the merger of two whi…
It is proposed that the gamma-ray photons that characterize the prompt emission of Gamma-Ray Bursts are produced through the Compton drag process, caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with Supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e. the overall energetics, the peak frequency of the spectrum and the fast variability, with an efficiency which can exceed 50%. In this scenario…
Supernova (SN) 1998bw and gamma-ray burst (GRB) 980425 offer the first direct evidence that supernovae are the progenitors of some GRBs. However, this burst was unusually dim, smooth and soft compared to other bursts with known afterglows. Whether it should be considered a prototype for cosmological GRBs depends largely on whether the supernova explosion and burst were asymmetrical or can be modeled as spherical. We address this question by treating the acceleration of the supernova shock in the outermost layers of the stellar envelope, the transition to relativistic flow, and the subsequent e…
When massive stars exhaust their fuel they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration gamma-ray burst. One would then expect that long gamma-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the long gamma-ray bursts are far more concentrated on the very brightest regions of their host galaxies than are the core-collapse supe…
We carry out a comprehensive theoretical examination of the relationship between the spatial distribution of optical transients and the properties of their progenitor stars. By constructing analytic models of star-forming galaxies and the evolution of stellar populations within them, we are able to place constraints on candidate progenitors for core-collapse supernovae (SNe), long-duration gamma ray bursts, and supernovae Ia. In particular we first construct models of spiral galaxies that reproduce observations of core-collapse SNe, and we use these models to constrain the minimum mass for SNe…
There are hints that nearby Type Ia supernovae may be a little different than those at large redshift. Confidence in the conclusion that there is a cosmological constant and an accelerating Universe thus still requires the hard work of sorting out potential systematic effects. Polarization data show that core-collapse supernovae (Type II and Ib/c) probably depart strongly from spherical symmetry. Evidence for exceedingly energetic supernovae must be considered self-consistently with evidence that they are asymmetric, a condition that affects energy estimates. Jets arising near the compact obje…
We present late-time radio observations of 68 local Type Ibc supernovae, including six events with broad optical absorption lines (``hypernovae''). None of these objects exhibit radio emission attributable to off-axis gamma-ray burst jets spreading into our line-of-sight. Comparison with our afterglow models reveals the following conclusions: (1) Less than $\sim 10%$ of Type Ibc supernovae are associated with typical gamma-ray bursts initially directed away from our line-of-sight; this places an empirical constraint on the GRB beaming factor of $<f_b^{-1}> \lesssim 10^4$ corresponding to an av…
The luminosity distance vs. redshift law is now measured using supernovae and gamma ray bursts, and the angular size distance is measured at the surface of last scattering by the CMB and at z = 0.35 by baryon acoustic oscillations. In this paper this data is fit to models for the equation of state with w = -1, w = const, and w(z) = w_0+w_a(1-a). The last model is poorly constrained by the distance data, leading to unphysical solutions where the dark energy dominates at early times unless the large scale structure and acoustic scale constraints are modified to allow for early time dark energy e…
The energy source of the giant HI supershells in nearby galaxies and in our own is still an unsettled issue. Proposed scenarios for production of near-complete ringlike supershells are multiple supernovae (SNe) and gamma-ray bursts (GRBs). In the late phase of evolution it is difficult to tell these models apart. We show that, if a supershell has been powered by multiple SNe, peculiar metal abundances should be found in the medium within the bubble. We present line diagnostics that could detect such unusual abundances, such as unusually high ratios of [O]/[Fe] and [Ne]/[Fe]. Among ions of the …
We discuss how rotation and binary interactions may be related to the diversity of type Ibc supernovae and long gamma-ray bursts. After presenting recent evolutionary models of massive single and binary stars including rotation, the Tayler-Spruit dynamo and binary interactions, we argue that the nature of SNe Ibc progenitors from binary systems may not significantly differ from that of single star progenitors in terms of rotation, and that most long GRB progenitors may be produced via the quasi-chemically homogeneous evolution at sub-solar metallicity. We also briefly discuss the possible role…
We report on the long term stability of the millisecond oscillations observed with the Rossi X-ray Timing Explorer (RXTE) during thermonuclear X-ray bursts from the low mass X-ray binaries (LMXB) 4U 1728-34 and 4U 1636-53. We show that bursts from 4U 1728-34 spanning more than 1.5 years have observed asymptotic oscillation periods which are within 0.2 microsec. of each other, well within the magnitude which could be produced by the orbital motion of the neutron star in a typical LMXB. This stability implies a timescale to change the oscillation period of > 23,000 years, suggesting a highly sta…
We present a new model for gamma-ray bursts (GRBs) that are not only associated with supernovae but also have small baryon contamination. In this model, we assume a newborn neutron star to move outward at a kick velocity of $\sim 10^3 {\rm km} {\rm s}^{-1}$ in the supernova ejecta. We find that such a neutron star still hypercritically accretes its surrounding supernova matter. Once the stellar mass increases to some critical mass, the neutron star will undergo a phase transition to become a strange star, leading to an energy release of a few $10^{52}$ ergs. The phase transition, if possibly o…
It is generally believed that cosmological Gamma Ray Bursts (GRBs) are produced by the deceleration of relativistic objects with Lorentz factor (Gamma) >~ 100. We study the possibility that some GRBs are produced along with relativistic matter ejection from supernovae. In this model, it is quite likely that the matter has to travel through the progenitor's thick envelope before generating GRBs. Under the assumption that the ejected matter is described as a single collective matter, we obtain constraints on the matter to have Gamma >~ 100 at the breakout of the progenitor. One advantage of cons…
Observational consequences of a jet-driven supernova (SN) explosion model are presented. The results are compared in detail with optical observations of SN 1998bw associated with a Gamma-Ray Burst. It is shown that the jet model is able to reproduce virtually all the optical observations available for this SN, although a spherical model fails to explain some of observed features. Because of the viewing angle effect, the required kinetic energy of the SN ejecta is reduced to ~ 2 x 10^{52} erg as compared to that obtained by the previous spherical model (~ 5 x 10^{52} erg), but this is still muc…
One of the most dramatic possible consequences of stellar rotation is its influence on stellar death, particularly of massive stars. If the angular momentum of the iron core when it collapses is such as to produce a neutron star with a period of 5 ms or less, rotation will have important consequences for the supernova explosion mechanism. Still shorter periods, corresponding to a neutron star rotating at break up, are required for the progenitors of gamma-ray bursts (GRBs). Current stellar models, while providing an excess of angular momentum to pulsars, still fall short of what is needed to m…
The degree of beaming in Gamma-Ray Bursts (GRBs) is currently unknown. The uncertainty in the gamma-ray beaming angle, theta, leaves the total energy release (proportional to theta^2) and the event rate per galaxy (proportional to 1/theta^2) unknown to within orders of magnitude. Since the delayed radio emission of GRB sources originates from a mildly relativistic shock and receives only weak relativistic beaming, the rate of radio-selected transients with no GRB counterpart can be used to set an upper limit on 1/theta^2. We find that a VLA survey with a sensitivity of 0.1 mJy at 10 GHz could …
Cosmological explosions such as core-collapse supernovae (SNe) and gamma-ray bursts (GRBs) are thought to be powered by the rapid conversion of roughly a solar mass' worth of gravitational binding energy into a comparatively small amount of outgoing observable kinetic energy. A fractional absorption of the emitted neutrinos, the particles which carry away the binding energy, by the expelled matter is a widely discussed mechanism for powering such explosions. Previous work addressing neutrino emission from core-collapse like environments assumes that the outgoing neutrino spectrum closely resem…
A toy model for gamma-ray burst-supernovae (GRB-SN) is discussed by considering the coexistence of baryon poor outflows from black holes (BHs) and a powerful spin-connection to surrounding disk, giving rise to consistent calorimetry as described by van Putten (2001a) in a variant of the Blandford-Znajek process (BZ, 1977). In this model the half-opening angle of the magnetic flux tube on the horizon is determined by the mapping relation between the angular coordinate on the BH horizon and the radial coordinate on the surrounding accretion disk. The GRB is powered by the baryon poor outflows in…
Within the framework of star formation in starburst galaxies undergoing interactions, connections among the red quasars, the BL Lacs, and the Blazars with the gamma-ray bursts are discussed in the light of the "hypernovae" scenario. It is proposed that the gamma-ray bursts occur primarily in the star formation regions in starburst environments, and arise from the core-collapse of super-massive Wolf-Rayet stars, that are formed in interacting systems. In this interacting environment star formations cause supernovae explosions. As the stars explode, shock waves propagate outward and collide with…
It has been argued that the observational limits on a supernova (SN) associated with GRB060614 convincingly exclude a SN akin to SN1998bw as its originator, and provide evidence for a new class of long-duration GRBs. We discuss this issue in the contexts of indirect 'redshift estimators' and of the fireball and cannonball models of GRBs. The latter explains the unusual properties of GRB060614: at its debated but favoured low redshift (0.125) they are predicted, as opposed to exceptional, if the associated core-collapse SN is of a recently discovered, very faint type. We take the occasion to di…
The energy output in the gamma-ray burst (GRB) prompt emission and afterglow phase is expected to photoionize the surrounding medium out to large radii. Cooling of this gas produces line emission, particularly strong in the optical, whose variability is a strong diagnostics of the gas density and geometry in the close environment of the burst. We present the results of a spectral time series analysis of the host galaxy of GRB 990712 observed up to ~6 years after the burst. We analyze the emission line fluxes together with those of the previous observations of the same GRB, in search for photoi…
The death of massive stars and the processes which govern the formation of compact remnants are not fully understood. Observationally, this problem may be addressed by studying different classes of cosmic explosions and their energy sources. Here we discuss recent results on the energetics of gamma-ray bursts (GRBs) and Type Ib/c Supernovae (SNe Ib/c). In particular, radio observations of GRB030329, which allow us to undertake calorimetry of the explosion, reveal that some GRBs are dominated by mildly relativistic ejecta such that the total explosive yield of GRBs is nearly constant, while the…
Core-collapse supernovae are among the most energetic explosions in the universe marking the catastrophic end of massive stars. In spite of rigorous studies for several decades, we still don't understand the explosion mechanism completely. Since they are related to many astrophysical phenomena such as nucleosynthesis, gamma-ray bursts and acceleration of cosmic rays, understanding of their physics has been of wide interest to the astrophysical community. In this article, we review recent progress in the study of core-collapse supernovae focusing on the explosion mechanism, supernova neutrinos,…
If Gamma-ray Bursts (GRBs) are generally associated with supernovae like 1998bw, a relatively wide intrinsic luminosity function is implied, which indicates the existence of a large amount of undetected dim bursts, and a much higher event-rate than is often assumed. If it is assumed that the intrinsic luminosity function of GRBs is a power-law: ${ϕ(L)} \propto {L^{-β}}$ ($β> 0$, $L_{min} \leq L \leq L_{max}$), data from the BATSE 4B catalog can be used to constrain slope index $β$ and the dynamic range width Log ${L_{max}\over L_{min}}$. Using a K-S test comparison with the observational Log $…
We point out that the already existing literature on relativistic collisionless MHD shocks show that the parameter sigma= upstream proper magnetic energy density/upstream rest mass energy density, plays an important role in determining the structure and accelerating properties of such shocks. By adopting a value of sigma= 0.002 which corresponds to the relativistic shock associated with the Crab nebula, and by using appropriate relativistic shock jump conditions, we obtain here a generous upper-limit on the value of (proper) the magnetic field, B ~ 1.5 10^{-3} eta n^{1/2} G, for gamma ray burs…
There is strong evidence that long duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. In the standard version of the Collapsar model, a broad-lined and luminous Type Ic core-collapse supernova (SN) accompanies the GRB. This association has been confirmed in observations of several nearby GRBs. Recent observations show that some long duration GRBs are different. No SN emission accompanied the long duration GRBs 060505 and 060614 down to limits fainter than any known Type Ic SN and hundreds of times fainter than the archetypal SN1998bw that accompanied GRB980425…
An $E_{γ,{\rm jet}}\propto {E'_p}^{1.5}$ relationship with a small scatter for current $γ$-ray burst (GRB) data was recently reported, where $E_{γ,{\rm jet}}$ is the beaming-corrected $γ$-ray energy and $E'_p$ is the $νF_ν$ peak energy in the local observer frame. By considering this relationship for a sample of 12 GRBs with known redshift, peak energy, and break time of afterglow light curves, we constrain the mass density of the universe and the nature of dark energy. We find that the mass density $Ω_M=0.35\pm^{0.15}_{0.15}$ (at the $1σ$ confident level) for a flat universe with a cosmologic…
We present the results of observations obtained using the MASTER robotic telescope in 2005 - 2006, including the earliest observations of the optical emission of the gamma-ray bursts GRB 050824 and GRB 060926. Together with later observations, these data yield the brightness-variation law t^{-0.55+-0.05} for GRB 050824. An optical flare was detected in GRB 060926 - a brightness enhancement that repeated the behavior observed in the X-ray variations. The spectrum of GRB 060926 is found to be F_E ~ E^-β, where β= 1.0+-0.2. Limits on the optical brightnesses of 26 gamma-ray bursts have been deriv…
If neutrino flavor changes really exist, to say: $μ$-neutrino oscillating into a sterile neutrino, then, it can be expected that due to neutrino oscillations and non-spherical distortion of the resonance surface induced by the magnetic field, some asymmetric emission of sterile neutrinos can occur during the protoneutron star formation at the onset of a supernova core-collapse. Assuming no strong suppression of the oscillations, the non-spherical huge neutrino energies released, ($\sim 10^{53-54} erg$), together with the proto-neutron star rapid rotation, may trigger powerful bursts of gravita…
HETE-2 has confirmed the connection between GRBs and Type Ic supernovae. Thus we now know that the progenitors of long GRBs are massive stars. HETE-2 has also provided strong evidence that the properties of X-Ray Flashes (XRFs) and GRBs form a continuum, and therefore that these two types of bursts are the same phenomenon. We show that both the structured jet and the uniform jet models can explain the observed properties of GRBs reasonably well. However, if one tries to account for the properties of both XRFs and GRBs in a unified picture, the uniform jet model works reasonably well while the …
When the afterglow fades at the site of a long-duration gamma-ray burst (LGRB), Type Ic supernovae (SN Ic) are the only type of core collapse supernova observed. Recent work found that a sample of LGRB in high-redshift galaxies had different environments from a collection of core-collapse environments, which were identified from their colors and light curves. LGRB were in the brightest regions of their hosts, but the core-collapse sample followed the overall distribution of the galaxy light. Here we examine 504 supernovae with types assigned based on their spectra that are located in nearby (z…
The supernova SN 2006aj associated with GRB 060218 is the second-closest GRB-SN observed to date (z=0.033). We present Very Large Telescope, Liverpool Telescope, and Katzman Automatic Imaging Telescope multi-color photometry of SN 2006aj. This supernova is found to be subluminous and rapidly evolving. Its early light curve includes an additional wavelength-dependent component, which can be interpreted as shock break-out. We compare the photometric evolution of multi-band light curves with the corresponding properties of the present sample of more than 10 GRB-SNe with precisely known redshifts.…
Mirror matter models have been suggested recently as an explanation of neutrino puzzles and microlensing anomalies. We show that mirror supernovae can be a copious source of energetic gamma rays if one assumes that the quantum gravity scale is in the TeV range. We show that under certain assumptions plausible in the mirror models, the gamma energies could be degraded to the 10 MeV range (and perhaps even further) so as to provide an explanation of observed gamma ray bursts. This mechanism for the origin of the gamma ray bursts has the advantage that it neatly avoids the ``baryon load problem''…
The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or supranova, model of gamma-ray bursts. Protons in the supernova remnant shell, and photons entrapped from a supernova explosion or a pulsar wind from a fast-rotating neutron star remnant provide ample targets for protons escaping the internal shocks of the gamma-ray burst to interact and produce high energy neutrinos. We calculate the expected neutrino fluxes, which can be detected by current and future…
A scenario is proposed that explains both the observed high pulsar velocities and extragalactic gamma-ray bursts (GRBs). The model involves an ultra- relativistic jet from a supernova (SN), that produces a GRB and its afterglow, whose characteristics are similar to an isotropic fireball GRB perhaps with some differences at late times in the afterglow once some significant transverse diffusion has occurred. The time scales and many other properties of GRBs and their afterglows in this model are consistent with observations. GRBs in this model have special intrinsic properties, that can either f…
We here propose a two-step model for gamma-ray bursts (GRBs) associated with supernovae. In the first step, the core collapse of a star with mass $\ge 19M_\odot$ leads to a massive neutron star and a normal supernova, and subsequently hypercritical accretion of the neutron star from the supernova ejecta may give rise to a jet through neutrino annihilation and/or Poynting flux along the stellar rotation axis. However, because of too much surrounding matter, this jet rapidly enters a nonrelativistic phase and evolves to a large bubble. In the second step, the neutron star promptly implodes to a …
The Novello-DeLorenci-Luciane (NDL) field theory of gravitation predicts that gravitational waves (GWs) follow geodesics of a modified (effective) geometry with a speed lower than the velocity of light. The theory also demonstrates that GWs exhibit the phenomenon of birefringence, formerly believed to be exclusive of electromagnetic waves. Here prospective astrophysical tests of these predictions are proposed. I point out that future measurements of gravitational waves in coincidence with a non-gravitational process such as {\it a neutrino burst} (and likely a burst of gamma-rays) may prove us…
A toy model for gamma-ray burst supernovae (GRB-SNe) is discussed by considering the effects of screw instability of magnetic field in black hole (BH) magnetosphere. The screw instability in the Blandford-Znajek (BZ) process (henceforth SIBZ) can coexist with the screw instability in the magnetic coupling (MC) process (henceforth SIMC). It turns out that both SIBZ and SIMC occur inevitably, provided that the following parameters are greater than some critical values, i.e., (i) the BH spin, (ii) the power-law index describing the magnetic field at the disk, and (iii) the vertical height of the …
It has been suggested that electromagnetic cascade of very high energy gamma-rays from gamma-ray bursts (GRBs) in the infrared/microwave background can produce delayed MeV-GeV photons. This delay could be caused by the angular spreading effect of the scattered microwave photons or deflection of the secondly pairs due to intergalactic magnetic field. Very high energy TeV photons of GRBs could be produced by a few mechanisms including the proton-synchrotron radiation and electron inverse Compton emission from GRB internal shocks as well as external shocks. We suggest that the information provide…
Using quasar spectra from the SDSS survey, we constrain the possibility of photon-axion oscillations as a source of dimming of high redshift objects. Such a process has been suggested as an explanation of the apparent faintness of distant Type Ia supernovae. For most combinations of magnetic field strengths and plasma densities along the line of sight, large beam attenuations in broad band filters would also lead to significant differential attenuation, not observed in the quasar sample. However, this conservative study does not exclude the possibility of 0.1 mag dimming of Type Ia supernovae …
We study centered and decentered nucleation of black holes in core-collapse of massive stars in binaries. By Bekenstein's gravitational-radiation recoil mechanism, a newly nucleated black hole typically leaves the central core prematurely. With low probability, the black hole remains centered and matures to a high-mass black hole which spins rapidly if the binary is compact. GRB030329/SN2003dh demonstrates that Type Ib/c supernovae are the parent population of long GRBs, whose branching ratio is ${\cal R}=(2-4)\times 10^{-3}$. We identify ${\cal R}$ with the low probability of centered nucleat…
We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with type Ic supernovae, and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution, and estimate the total energy budget based upon broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and sub-relativistic form. The result is a glo…
Gamma ray bursts are excellent candidates to constrain physical models which break Lorentz symmetry. We consider deformed dispersion relations which break the boost invariance and lead to an energy-dependent speed of light. In these models, simultaneously emitted photons from cosmological sources reach Earth with a spectral time delay that depends on the symmetry breaking scale. We estimate the possible bounds which can be obtained by comparing the spectral time delays with the time resolution of available telescopes. We discuss the best strategy to reach the strongest bounds. We compute the p…
We suggest that the collapsing core of a massive rotating star may fragment to produce two or more compact objects. Their coalescence under gravitational radiation gives the resulting black hole or neutron star a significant kick velocity, which may explain those observed in pulsars. A gamma-ray burst can result only when this kick is small. Thus only a small fraction of core-collapse supernovae produce gamma-ray bursts. The burst may be delayed significantly (hours - days) after the supernova, as suggested by recent observations. If this picture is correct, core-collapse supernovae should be …
Long-duration gamma-ray bursts (GRBs) are thought to be connected to luminous and energetic supernovae (SNe), called hypernovae (HNe), resulting from the black-hole (BH) forming collapse of massive stars. For recent nearby GRBs~060505 and 060614, however, the expected SNe have not been detected. The upper limits to the SN brightness are about 100 times fainter than GRB-associated HNe (GRB-HNe), corresponding to the upper limits to the ejected $^{56}$Ni masses of $M({\rm ^{56}Ni})\sim 10^{-3}M_\odot$. SNe with a small amount of $^{56}$Ni ejection are observed as faint Type II SNe. HNe and faint…
