Cerenkov light images of EAS produced by primary gamma

It is shown that it should be possible to distinguish very effectively between background hadronic showers and TeV gamma ray showers from a point source on the basis of the width, length and orientation of the Cerenkov light images of the shower, seen in the focal plane of a focusing mirror, even with a relatively coarse pixel size such as employed in the Mt. Hopkins detector. Predictions of the response of this system to air showers are presented

UHE particle production in close binary systems

Cygnus X-3 appears to generate so much power in the form of charged particles of up to approx 10 to the 17th power eV that the galaxy may need approx 1 such source on average to maintain its flux of ultra high energy cosmic rays. Accreting gas must supply the energy, and in a surprisingly ordered form, if it is correct to use a Vest-rand-Eichler model for radiation of gammas, modified by the introduction of an accretion wake. Certain relationships between 10 to the 12th power eV and 10 to the 15th power gamma rays are expected

Why is Cygnus X-3 (with related sources) a highlight of cosmic-ray astrophysics?

Cygnus X-3 and some apparently related systems have sprung into remarkable prominence. The reasons for this great interest are summarized. Some recent developments in the picture of these sources are also outlined

Multi-GeV Neutrino Emission from Magnetized Gamma Ray Bursts

We investigate the expected neutrino emissivity from nuclear collisions in magnetically dominated collisional models of gamma-ray bursts, motivated by recent observational and theoretical developments. The results indicate that significant multi-GeV neutrino fluxes are expected for model parameter values which are typical of electromagnetically detected bursts. We show that for detecting at least one muon event in Icecube and its Deep Core sub-array, a single burst must be near the high end of the luminosity function and at a redshift $z\lesssim 0.2$. We also calculate the luminosity and distance ranges that can generate $0.01-1$ muon events per GRB in the same detectors, which may be of interest if simultaneously detected electromagnetically, or if measured with future extensions of Icecube or other neutrino detectors with larger effective volume and better sensitivity.Comment: 12 pages, 7 figures, accepted version for Phys.Rev.

Ultra-high energy cosmic rays may come from clustered sources

Clustering of cosmic-ray sources affects the flux observed beyond the cutoff imposed by the cosmic microwave background and may be important in interpreting the AGASA, Fly's Eye, and HiRes data. The standard deviation, sigma, in the predicted number, N, of events above 10^{20} eV is sigma/N = 0.9(r_0/10 Mpc)^{0.9}, where r_0 is the unknown scale length of the correlation function (r_0 = 10 Mpc for field galaxies). Future experiments will allow the determination of r_0 through the detection of anisotropies in arrival directions of ~ 10^{20} eV cosmic-rays over angular scales of Theta ~ r_0/30 Mpc.Comment: Accepted for publication in Astrophysical Journa

Locating very high energy gamma ray sources with arc minute accuracy

The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of point-like sources were detected by the COS-B satellite, only two were unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of Very High Energy gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arc minute accuracy. This was demonstrated using Cerenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg

Detection Techniques of Microsecond Gamma-Ray Bursts using Ground-Based Telescopes

Gamma-ray observations above 200 MeV are conventionally made by satellite-based detectors. The EGRET detector on the Compton Gamma Ray Observatory (CGRO) has provided good sensitivity for the detection of bursts lasting for more than 200 ms. Theoretical predictions of high-energy gamma-ray bursts produced by quantum-mechanical decay of primordial black holes (Hawking 1971) suggest the emission of bursts on shorter time scales. The final stage of a primordial black hole results in a burst of gamma-rays, peaking around 250 MeV and lasting for a tenth of a microsecond or longer depending on particle physics. In this work we show that there is an observational window using ground-based imaging Cherenkov detectors to measure gamma-ray burst emission at energies E greater than 200 MeV. This technique, with a sensitivity for bursts lasting nanoseconds to several microseconds, is based on the detection of multi-photon-initiated air showers.Comment: accepted for publication in the Astrophysical Journa