A difference method of searching for spectral-spatial fluctuations of the cosmic microwave background radiation

We consider methods of searching for the spectral-spatial fluctuations of the cosmic microwave background radiation that were formed in the early Universe. Based on the narrow-band spatial-frequency properties of these fluctuations, we suggest a difference method of their search. We describe the method and present our simulation results. This technique is shown to have a significant advantage over the existing methods. We give recommendations to optimize the observing and reduction procedures.     

Observational manifestations of prerecombination protoobjects

We consider the image formation for an extremely distant source in an optically dense, homogeneous, and isotropic medium. We show that the angular size of the image would presently be θ₀ ≈ 10′, irrespective of the initial redshift z. Parameters of the inhomogeneities capable of producing the observed effect were estimated. We note that this effect should be taken into account for the baryon density fluctuations that were damped according to Silk at the prerecombination epoch. The spot radiation spectrum is shown to be a diluted Planckian spectrum with a dilution factor much larger than unity. We also point out the presence of peculiar tangential polarization in the spot, which reaches several tens of percent at the spot edge. All these observational features clearly distinguish the fluctuations under consideration from the standard fluctuations.     

Cosmological constraints on the neutrino mass from CMB anisotropy and large-scale structure of the Universe

Using cosmological data on the CMB anisotropy and large-scale structure of the Universe, we have obtained new constraints on the sum of the masses of three generations of active neutrinos: Σm _ν < 1.05 eV (95% confidence level). Data of the third year of the WMAP mission served as the source of CMB anisotropy data. The mass functions of X-ray clusters of galaxies were taken as the data on the large-scale structure of the Universe. The observational properties of the clusters were obtained during the ROSAT mission and the assumption that the baryon fraction is universal in the Universe was used to determine the total cluster mass.     

Formation mechanisms of “Negative”-intensity spots in the cosmic microwave background radiation and distant objects

We consider the formation mechanisms of “negative”-intensity spots in the radio band for various astrophysical conditions. For wavelengths λ<1.5 mm, the regions of reduced temperature (relative to the cosmic microwave background radiation, CMBR) are shown to be produced only by high-redshift objects moving at peculiar velocities. The main processes are CMBR Thomson scattering and bremsstrahlung. We show that the effect δT/T can be ～10^?5 in magnitude. We derive simple analytic expressions, which allow the redshifts, electron densities, and linear sizes of these regions to be estimated from observed spectral and spatial parameters. Additional observational methods for refining these parameters are outlined.     

Effects of possible deviations of fundamental physical constants on primordial nucleosynthesis

We study the effects of possible deviations of fundamental physical constants on the yields of light nuclides, ²D, ³He, ⁴He, ⁷Li, and others during primordial nucleosynthesis. The deviations of fundamental constants from their current values are considered in the low-energy approximation of string theories; the latter predict the existence of a scalar field, which, apart from the tensor gravitational field, determines the space geometry. A two-parameter (η, δ) model is constructed for primordial nucleosynthesis: η = n _B /n _γ is the baryon-to-photon density ratio, and Ω is the relative deviation of fundamental physical constants at the epoch of primordial nucleosynthesis from their current values. A dependence of η on the deviation of coupling constants Ω has been derived on condition that the primordial helium abundance is Y _p = f(η, δ) = const, where const corresponds to experimental values. We thus showed that the relative baryonic density (and hence Ω_B could vary over a much wider range than allowed by the standard nucleosynthesis model. Considering this result, we discuss the recently found mismatch between Ω_B obtained from an analysis of CMBR anisotropy and from the standard primordial nucleosynthesis model.     

The Wilkinson Microwave Anisotropy Probe (WMAP) confirmed the model of our observed relativistic universe

The Wilkinson Microwave Anisotropy Probe (WMAP) confirmed the model of flat expansive homogeneous and isotropic relativistic universe, which describes the properties of our observed flat expansive homogeneous and isotropic relativistic Universe in the first (linear, Newtonian or classical-mechanical) approximation.     

Do the fundamental constants vary in the course of cosmological evolution?

The possible cosmological variation of the proton-to-electron mass ratio μ = m _p/m _e was estimated by measuring the H₂ wavelengths in the spectra of distant quasars. We analyze high-resolution (FWHM≈7 km s^?1) spectra of the two damped Lyman-α systems at redshifts z _abs=2.3377 and 3.0249 observed in the spectra of the quasars Q 1232+082 and Q 0347?382, respectively. Our analysis yielded the most conservative estimate for the possible variation of μ in the past ～ 10 Gyr, Δμ/μ = (5.7 ± 3.8) × 10^?5. Since the significance of this result does not exceed 1.5σ, further observations are needed to increase the statistical significance. This is the most stringent limit on the possible cosmological variation of μ to date.     

Search for gravitational lenses near the extragalactic double object CSL-1

We consider additional arguments in favor of the first observable cosmic string. We discuss candidates for gravitational lensing events near the extragalactic double source CSL-1 (Capodimonte-Sternberg-Lens Candidate no. 1) discovered in the Osservatorio Astronomico di Capodimonte Deep Field (OACDF). The detected excess of candidates for such events cannot be explained in terms of the theory of gravitational lensing by standard extragalactic objects (galaxies, groups of galaxies, etc.) and is in close agreement with the proposed model of gravitational lensing by a cosmic string.     

Comparison of stellar orbits in various models of the galaxy

We compare the properties of orbits in five different rotationally symmetric models of the regular Galactic force field. Our goal is to estimate the possible range of the discrepancies in stellar orbital elements attributable to the choice of the model for the Galactic potential. For disk objects, the discrepancies in eccentricities e attributable to the choice of the model do not exceed 0.05. The relative distances h from the symmetry plane can differ by more than a factor of 2. Since there are resonance regions, the types of orbits (box-shaped or tube-shaped) cannot be reliably identified. The situation is even worse for halo objects: the discrepancies in h can exceed 100%, and identifying the type of orbits is also highly problematic.     

The coincidence of friedmann integrals

The expansion of a two-component Universe with an arbitrary spatial curvature is considered. It is shown that the Friedmann integrals of an almost flat Universe do not coincide.     

Radial distributions of gamma-ray bursts and type Ib/c supernovae in galaxies

Data on the positions of gamma-ray bursts (GRBs) in galaxies are used to construct the radial distributions of their surface density. The gradient in GRB surface density is shown to decrease sharply at a galactocentric distance equal to the effective galactic radius. In central galactic regions, the GRB density distribution agrees with the galactic surface-brightness distribution; in outer regions, the GRB density decreases more slowly than does the surface brightness. Based on improved statistics, we analyze the radial distribution of type Ib/c supernovae. We show that it differs insignificantly from the distributions of other types of supernova and exhibits a much closer similarity to the distribution of star-forming regions than do GRBs. Although the statistics for GRBs is poor, the deviation of their distribution from the distribution of active star-forming regions in nearby galaxies seems to have been firmly established. A correlation of GRBs with the distribution of dark matter in outer galactic regions is not ruled out.     

The observed structure of extremely distant galaxies

We have identified 22 galaxies with photometric redshifts z_ph=5–7 in the northern and southern Hubble Space Telescope deep fields. An analysis of the images of these objects shows that they are asymmetric and very compact (～1 kpc) structures with high surface brightness and absolute magnitudes of M_B≈?20^m. The average spectral energy distribution for these galaxies agrees with the distributions for galaxies with active star formation. The star formation rate in galaxies with z_ph=5–7 was estimated from their luminosity at λ=1500 Å to be ~30 M_⊙yr^?1. The spatial density of these objects is close to the current spatial density of bright galaxies. All the above properties of the distant galaxies considered are very similar to those of the so-called Lyman break galaxies (LBGs) with z ～ 3–4. The similarity between the objects considered and LBGs suggests that at z ～6, we observe the progenitors of present-day galaxies that form duringmergers of protogalactic objects and that undergo intense starbursts.     

The baryon mass distribution for nearby galaxy clusters

Based on ROSAT X-ray data, we constructed the baryon mass function for a statistically complete sample of galaxy clusters at redshifts of 0.01–0.1. Since the derived function is similar to the total mass function for clusters, it can be used to determine cosmological parameters.     

Influence of cosmological expansion on the threshold effects in the annihilation reaction of hard photons with CMB photons

The redshift (z) dependence of the dispersion relations for free particles is analyzed by taking into account the Lorentz invariance violation. A nonlinear algebraic equation is derived for the momenta of the particles involved in the annihilation reaction of a hard photon from a γ-ray source with a soft cosmic microwave background (CMB) photon near the threshold of this reaction. The solutions of this threshold equation are constructed and analyzed as a function of the redshift. We show that the threshold of the reaction under consideration tends to decrease with increasing z; the energy spectra of γ-ray sources at energies of ～10 TeV must be cut off in accordance with the calculated z dependence. We also calculate the time delay of the light signals from γ-ray sources that corresponds to the Lorentz invariance violation for photons. We discuss the possibility of improving the standard constraints on the Lorentz invariance violation parameters for fields of various physical natures.     

Hydrogen absorption lines in the cosmic microwave background spectrum

We have calculated the intensities of the subordinate hydrogen lines formed during the recombination epoch at redshifts 800?z?1600. We show that an allowance for the angular momentum splitting of hydrogen atomic energy levels and the dipole transition selection rules can reveal absorption features in the cosmic microwave background recombination spectrum in the submillimeter wavelength range.     

HD molecular lines in an absorption system at redshift z=2.3377

Having analyzed the spectrum of the quasar PKS 1232+0.82 taken by Petitjean et al. (2000), we identified HD molecular lines in an absorption system at redshift z=2.3377. We estimated the column density of HD molecules in this system, N(HD) = (1?4) × 10¹⁴cm^?2. The excitation temperature of the first rotational level J=1 relative to the ground state J=0 is T _ex=70 ± 7 K. As far as we know, this is the first detection of HD molecules at high redshift.     

Morphology and Luminosity Segregations in Galaxy Groups

We study morphology and luminosity segregation of galaxies in groups. We analyze the two catalogs of (∼2×400) groups which have been identified in the Nearby Optical Galaxy sample, by means of hierarchical and percolation `friends-of-friends' methods. We find that earlier-type (brighter) galaxies are more clustered and lie closer to the group centers, both in position and in velocity, than later-type (fainter) galaxies. Spatial segregations are stronger than kinematical segregations. These effects are generally detected at the ≳3-sigma level, with the exception of morphological segregation in velocity, which is the weakest effect. Our main results are confirmed by the analysis of statistically more reliable groups (with at least five members), and are strengthened by the detection of segregation in both hierarchical and percolation catalogs. Luminosity segregation is shown to be independent of morphology segregation. Our conclusions agree with a continuum of segregation properties of galaxies in systems, from low-mass groups to massive clusters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Circular scans for cosmic microwave background anisotropy observation and analysis

A number of experiments for measuring anisotropies of the cosmic microwave background (CMB) use scanning strategies in which temperature fluctuations are measured along circular scans on the sky. It is possible, from a large number of such intersecting circular scans, to build two-dimensional sky maps for subsequent analysis. However, since instrumental effects — especially the excess low-frequency 1/ f noise — project on to such two-dimensional maps in a non-trivial way, we discuss the analysis approach which focuses on information contained in the individual circular scans. This natural way of looking at CMB data from experiments scanning on the circles combines the advantages of elegant simplicity of Fourier series for the computation of statistics useful for constraining cosmological scenarios, and superior efficiency in analysing and quantifying most of the crucial instrumental effects.