A W Wolfendale

Corrections to virial estimates of molecular cloud masses

The application of the virial theorem to the determination of giant molecular cloud masses is reconsidered. It is argued that it is necessary to transform the results to equivalent velocity widths for the optically thin line of (C-13)O rather than that of (C-12)O. The results lead to a substantial lowering of H2 mass and values of X closer to that of the gamma-ray analysis of Bhat et al. (1986). The total mass of H2 in the Inner Galaxy is significantly less than that of atomic hydrogen. 27 references.

Observational Tests of Cosmological Inflation

I. Inflation Theory.- Fundamental Arguments for Inflation.- Predictions of Inflation.- Classicality of Density Perturbations in the Early Universe.- The Influence of Non-Linear Density Fluctuations on the Microwave Sky.- Quantum Cosmology and the Cosmological Constant.- Lessons from Inflation and Cold Dark Matter.- The Topology of Galaxy Clustering.- Can Non-Gaussian Fluctuations for Structure Formation Arise from Inflation.- Non-Baryonic Dark Matter.- Are Galactic Halos Made of Brown Dwarfs or Black Holes.- II. Cosmological Timescale Test.- Ages of Globular Clusters.- Globular Cluster Ages and Cosmology.- The Local Distance Scale: How Reliable Is It.- Distances to Virgo and Beyond.- The Luminosity-Line-Width Relations and the Value of Ho.- Observational Status of HO.- Calibrating Cepheid Sequences in Nearby Galaxies.- New D-? Results for Coma Ellipticals.- Novae and the Distance Scale.- A High Resolution, Ground Based Observation of a Virgo Galaxy.- Globular Clusters as Extragalactic Distance Indicators.- III. High Redshift Tests of ?o.- High-Redshift Tests of ?.- Cosmology with Galaxies at High Redshifts.- Prospects for Measuring the Deceleration Parameter.- Aligned Radio Galaxies.- K Band Galaxy Counts and the Cosmological Geometry.- Selection Effects in Redshift Surveys.- An Inflationary Alternative to the Big-Bang.- IV. Galaxy Clustering, ?o and the Primordial Spectrum.- Dynamical Estimates of ?o from Galaxy Clustering.- ROSAT Observations of Clusters of Galaxies.- A Deep ROSAT Observation at High Galactic Latitude.- Large Scale Structure and Inflation.- The Structure of the Universe on Large Scales.- Testing the Zeldovich Spectrum.- ? on the Scale of 3Mm/s.- Tests of Inflation Using the QDOT Redshift Survey.- Testing Inflation with Peculiar Velocities.- The Invisible Cosmological Constant.- Support for Inflation from the Great Attractor.- The Angular Large Scale Structure.- Is There Any Observational Evidence for Non- Gaussian Primordial Density Fluctuations.- V. Microwave Background Anisotropy.- COBE DMR Observations of CMB Anisotropy.- Observations of Microwave Background Anisotropy at Tenerife and Cambridge.- Foreground Effects and the Search for Fluctuations in the CMB Radiation.- Microwave Background Anisotropics and Large Scale Structure in the Universe.- Discovery of the Small Scale Sky Anisotropy at 2.7cm: Radio Sources or Relic Emission.- Balloon-Borne Observations of CMB Anisotropics at Intermediate Angular Scales, at Sub-MM and MM Wavelengths.- VI. Poster Papers.- The Durham/UKST Galaxy Redshift Survey.- Time Evolution of Lensed Image Separations.- Deep Galactic Surveys as Probes of the Large Scale Structure of the Universe.- Intergalactic Absorption in the Spectra of High-Redshift QSOs.- A Complete Quasar Sample at Intermediate Redshift.- Radio-Luminosity Dependence of the IR-Radio Alignment Effect in High-z Radio Galaxies.- Density and Peculiar Velocity Fields in the Region of Dresslers Supergalactic Plane Survey.- Scale Invariance Induced by Non-linear Growth of Density Fluctuations.- The Power Spectrum of Galaxy Clustering.- Higher Moments of the IRAS Galaxy Distribution.- Collapse of a Protogalactic Cloud.- Index of Authors.

The Anisotropy of Galactic Cosmic Rays as a Product of Stochastic Supernova Explosions

We study the effect of the stochastic character of supernova explosions on the anisotropy of galactic cosmic rays below the knee. We conclude that if the bulk of cosmic rays are produced in supernova explosions the observed small and nearly energy independent amplitude of the anisotropy and its phase are to the large extent determined by the history of these explosions in the vicinity of the solar system, namely by the location and the age of the supernova remnants, within a few kpc, which give the highest contribution to the total intensity at the present epoch. Among the most important factors which result in the small magnitude and the energy independence of the anisotropy amplitude are the mixed primary mass composition, the effect of the Single Source and the Galactic Halo. Special attention is given to the phase of the anisotropy. It is shown that the excessive flux from the Outer Galaxy can be due to the location of the solar system at the inner edge of the Orion Arm which has the enhanced density and rate of supernova explosions.

Cosmic ray decreases and changes in the liquid water cloud fraction over the oceans

Svensmark et al. (2009) have recently claimed that strong galactic cosmic ray (GCR) decreases during Forbush Decrease (FD) events are followed by decreases in both the global liquid water cloud fraction (LCF) and other closely correlated atmospheric parameters. To test the validity of these findings we have concentrated on just one property, the MODIS LCF and examined two aspects: 1) The statistical chance that the decrease observed in the LCF is abnormal. 2) The likelihood of the observed delay (5 to 9 days) being physically connected to the FD events. On both counts we conclude that LCF variations are unrelated to FD events: Both the pattern and timing of observed LCF changes are irreconcilable with current theoretical pathways. Additionally, a zonal analysis of LCF variations also offers no support to the claimed relationship, as the observed anomaly is not found to vary latitudinally in conjunction with cosmic ray intensity.

On the correlation between cosmic ray intensity and cloud cover

Abstract Various aspects of the connection between cloud cover (CC) and cosmic rays (CR) are analyzed. Most features of this connection viz. an altitude dependence of the absolute values of CC and CR intensity, no evidence for the correlation between the ionization of the atmosphere and cloudiness, the absence of correlations in short-term low cloud cover (LCC) and CR variations indicate that there is no direct causal connection between LCC and CR in spite of the evident long-term correlation between them. However, these arguments are indirect. If only some part of the LCC is connected and varies with CR, then its value, obtained from the joint analysis of their 11-year variations and averaged over the Globe, should be most likely less than 20%. The most significant argument against causal connection of CR and LCC is the anticorrelation between LCC and the medium cloud cover (MCC). The scenario of the parallel influence of the solar activity on the Global temperature and CC from one side and CR from the other side, which can lead to the observed correlations, is discussed and advocated.

Solar activity and the mean global temperature

The variation with time from 1956 to 2002 of the globally averaged rate of ionization produced by cosmic rays in the atmosphere is deduced and shown to have a cyclic component of period roughly twice the 11 year solar cycle period. Long term variations in the global average surface temperature as a function of time since 1956 are found to have a similar cyclic component. The cyclic variations are also observed in the solar irradiance and in the mean daily sun spot number. The cyclic variation in the cosmic ray rate is observed to be delayed by 2?4 years relative to the temperature, the solar irradiance and daily sun spot variations suggesting that the origin of the correlation is more likely to be direct solar activity than cosmic rays. Assuming that the correlation is caused by such solar activity, we deduce that the maximum recent increase in the mean surface temperature of the Earth which can be ascribed to this activity is of the observed global warming.

Primary cosmic γrays above 1012 eV

An analysis is made of the interactions of very energetic cosmic ray primaries with the universal black body radiation in extragalactic space. The gamma rays from the initial pi 0 mesons produce electron pairs in collisions with further black body photons and a gamma -e cascade builds up through this interaction and the inverse Compton interaction. Results are given for the expected gamma -ray spectrum at the earth for a variety of assumptions about the magnitude of the primary spectrum and other parameters and comparison is made with upper limits to the gamma -ray intensity from experimental data. One conclusion that arises immediately is that if the higher of the two primary proton energy spectra is correct then the extragalactic infrared energy density must be less than about 2 eV cm-3. In general the predicted gamma to proton ratios are highest in the region of 3*1019 eV. They are mostly below present detection limits but should be detectable with the improved extensive air shower arrays at present being constructed.

Properties of the interstellar medium and the propagation of cosmic rays in the Galaxy

Abstract The problem of the origin of cosmic rays in the shocks produced by supernova explosions at energies below the so-called ‘knee’ (at ∼3×106 GeV) in the energy spectrum is addressed, with special attention to the propagation of the particles through the inhomogeneous interstellar medium (ISM) and the need to explain recent anisotropy results [Proc. 27th Int. Conf. Cosmic Rays, Hamburg 1 (2001) 10]. It is shown that the fractal character of the matter density and magnetic field distribution leads to the likelihood of a substantial increase of spatial fluctuations in the cosmic ray energy spectra. While the spatial distribution of cosmic rays in the vicinity of their sources (e.g. inside the Galactic disk) does not depend much on the character of propagation and is largely determined by the distribution of their sources, the distribution at large distances from the Galactic disk depends strongly on the character of the propagation. In particular, the fractal character of the ISM leads to what is known as ‘anomalous diffusion’ and such diffusion helps us to understand the formation of the cosmic ray halo. Anomalous diffusion allows an explanation of the recent important result from the Chacaltaya extensive air shower experiment [Proc. 27th Int. Conf. Cosmic Rays, Hamburg 1 (2001) 10], viz. a Galactic plane enhancement of cosmic ray intensity in the outer Galaxy, which is otherwise absent for the case of the so-called ‘normal’ diffusion. All these effects are for just one reason: anomalous diffusion emphasizes the role of local phenomena in the formation of cosmic ray characteristics in our Galaxy and elsewhere.

THE INTERRELATION OF THE PRIMARY AND SEA-LEVEL SPECTRA OF COSMIC RAYS

Recent measurements of the sea-level spectra of cosmic ray protons and muons have been used, together with a trial spectrum of primary nucleons, to derive values for the nucleon inelasticity Kt and the fraction of energy passed on to the pion component Kπ in nucleon-air-nucleus collisions. It is shown that the values of Kt and Kπ are not very sensitive to the model assumed for the collisions, and the effect of fluctuations in the values of Kt and Kπ from one collision to the next is found to be small. Assuming a value for the difference Kt-Kπ based on the results of other experiments (approximately 0.12) it is possible to estimate the energy spectrum of primary nucleons in the range 1011-1015 ev/nucleon. When recent geomagnetic measurements are added, the integral spectrum is found to be represented by the expression I(>E) = 0.87+0.52-0.30E-1.58 cm-2 sec-1 sterad-1 over the range 1010-3 × 1013 ev/nucleon, where E is expressed in GeV. At higher energies the exponent increases reaching a value of about 2.1 in the region of 1015 eV. It Kt-Kπ is less than 0.12 the primary intensity is reduced; in the limit, with Kt-Kπ = 0 the intensity is reduced by a factor of approximately 1.5.

The diffuse flux of energetic extragalactic gamma rays

An improved determination is made of the energy spectrum of the so-called diffuse component of extragalactic gamma rays over the range 30 MeV-10 GeV. The data used comprise gamma ray spectra from the EGRET instrument on the Compton Gamma Ray Observatory and a variety of information on the column densities of gas in various forms (atomic and molecular hydrogen and ionized material) together with model predictions of the contribution from inverse Compton interactions, all the latter being necessary in order to evaluate the corrections to be applied for gamma rays of Galactic origin. Deleting only one known extragalactic source (the gamma -bright quasar 3C 279) the differential intensity is given by I(Egamma )=9.6*10-7 E- gamma cm-2 s-1 sr-1 GeV-1 with gamma =2.11+or-0.05 above 50 MeV. At lower energies there is some evidence for a somewhat lower intensity. The corresponding energy density in extragalactic space is 1.9*10-6 eV cm-3 in the range 100 MeV-10 GeV. The significance of the measured flux is examined.