Is the diffuse gamma background radiation generated by galactic cosmic rays?

We explore the possibility that the diffuse gamma-ray background radiation (GBR) at high galactic latitudes could be dominated by inverse Compton scattering of cosmic ray (CR) electrons on the cosmic microwave background radiation and on starlight from our own galaxy. Assuming that the mechanisms accelerating galactic CR hadrons and electrons are the same, we derive simple and successful relations between the spectral indices of the GBR above a few MeV, and of the CR electrons and CR nuclei above a few GeV. We reproduce the observed intensity and angular dependence of the GBR, in directions away from the galactic disk and centre, without recourse to hypothetical extragalactic sources.Comment: Submitted for publicatio

Is there a 1998bw-like supernova in the afterglow of gamma ray burst 011121?

We use the very simple and successful Cannonball Model (CB) of gamma ray bursts (GRBs) and their afterglows (AGs) to analyze the observations of the strongly extinct optical AG of the relatively nearby GRB 011121, which were made with ground-based telescopes at early times, and with the HST at later time. We show that GRB 011121 was indeed associated with a 1998bw-like supernova at the GRB's redshift, as we had specifically predicted for this GRB before the supernova could be observed.Comment: Submitted for publicatio

A common origin of all the species of high-energy cosmic rays?

Cosmic ray nuclei, cosmic ray electrons with energy above a few GeV, and the diffuse gamma-ray background radiation (GBR) above a few MeV, presumed to be extragalactic, could all have their origin or residence in our galaxy and its halo. The mechanism accelerating hadrons and electrons is the same, the electron spectrum is modulated by inverse Compton scattering on starlight and on the microwave background radiation; the $\gamma$-rays are the resulting recoiling photons. The spectral indices of the cosmic-ray electrons and of the GBR, calculated on this simple basis, agree with observations. The angular dependence and the approximate magnitude of the GBR are also explained.Comment: Includes a discussion of the contribution of inverse Compton scattering of CR electrons by starlight in the halo to the gamma background radiation. One corrected typo. Additional references, and figures to compare predictions for the angular dependence of the gamma background radiation with data. Conclusions are unchange

The vicissitudes of "cannonballs": a response to criticisms by A.M. Hillas and a brief review of our claims

A.M. Hillas, in a review of the origins of cosmic rays, has recently criticized the "cannonball" (CB) model of cosmic rays and gamma-ray bursts. We respond to this critique and take the occasion to discuss the crucial question of particle acceleration in the CB model and in the generally accepted models. We also summarize our claims concerning the CB model

A solution of a hoary conundrum: the origin and properties of cosmic rays

I discuss a theory of non-solar cosmic rays (CRs) based on a single type of CR source at all energies. All observed properties of CRs are predicted in terms of very simple and completely `standard' physics. The source of CRs is extremely `economical': it has only one parameter to be fitted to the enormous ensemble of all of the data. All other inputs are `priors', that is theoretical or observational items of information independent of the properties of the source of CRs and chosen to lie in their pre-established ranges.Comment: 10 pages, 13 figures. Contribution to the Cosmic Ray International Seminar, Catania, 200

Origin of the ultrahigh-energy cosmic rays and their spectral break

The energy spectrum, composition and arrival directions of ultrahigh energy cosmic rays (UHECRs) with energy above the cosmic ray ankle, measured by the Pierre Auger Observatory, appear to be in conflict if their origin is assumed to be extragalactic. Their spectrum and composition, however, are those expected from Galactic UHECRs accelerated by highly relativistic jets such as those producing short hard gamma ray bursts (SHBs). If this alternative interpretation is correct, then the observed break in the energy spectrum of UHECRs around 50 EeV is the energy threshold for free escape of UHE iron nuclei from the Galaxy and not the Greisen-Zatsepin-Kuzmin (GZK) cutoff for protons, and the arrival directions of UHECR nuclei with energy above their UHE breaks must point back to their Galactic sources rather than to active galactic nuclei (AGN) within the GZK horizon

Long gamma-ray bursts without visible supernovae: a case study of redshift estimators and alleged novel objects

There is an ongoing debate on whether or not 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 low redshift (0.125) they are predicted, as opposed to exceptional, if the associated SN is of `Pastorello's class'. Long-baseline radio data and deep optical data may test the proposed alternatives

The rapid decline of the prompt emission in Gamma-Ray Bursts

Many gamma ray bursts (GRBs) have been observed with the Burst-Alert and X-Ray telescopes of the Swift satellite. The successive `pulses' of these GRBs end with a fast decline and a fast spectral softening, until they are overtaken by another pulse, or the last pulse's decline is overtaken by a less rapidly-varying `afterglow'. The fast decline-phase has been attributed, in the currently-explored standard fireball model of GRBs, to `high-latitude' synchrotron emission from a collision of two conical shells. This high latitude emission does not explain the observed spectral softening. In contrast, the temporal behaviour and the spectral evolution during the fast-decline phase agree with the predictions of the cannonball model of GRBs.Comment: Four added figures comparing the evolution of the inferred effective photon spectral index during the fast decline phase of the prompt emission in 14 selected Swift GRBS and the cannonball (CB) model predictio

Critical Tests of Leading Gamma Ray Burst Theories II

It has been observationally established that supernovae (SNe) of Type Ic produce long duration gamma ray bursts (GRBs) and that neutron star mergers generate short hard GRBs. SN-Less GRBs presumably originate in a phase transition of a neutron star in a high mass X-ray binary. How these phenomena actually generate GRBs is debated. The fireball and cannonball models of GRBs and their afterglows have been widely confronted with the huge observational data, with their defenders claiming success. The claims, however, may reflect multiple choices and the use of many adjustable parameters, rather than the validity of the models. Only a confrontation of key falsifiable predictions of the models with solid observational data can test their validity. Such critical tests are reviewed in this report.Comment: An updated rendering of arXiv:1810.03514 with an extra autho

Will relativistic heavy-ion colliders destroy our planet?

Experiments at the Brookhaven National Laboratory will study collisions between gold nuclei at unprecedented energies. The concern has been voiced that ``strangelets''-hypothetical products of these collisions - may trigger the destruction of our planet. We show how naturally occurring heavy-ion collisions can be used to derive a safe and stringent upper bound on the risk incurred in running these experiments.Comment: LaTeX, no figure