Estimates of Extragalactic Background and Confusion Noise Parameters for the Millimetron Telescope

Astronomy Letters - The sensitivity of future far-infrared telescopes, such as Millimetron, will be limited by the confusion noise produced by distant galaxies. We have constructed a model of the...     

Confusion Noise Sources in the Infrared Wavelength Range

Astronomy Reports - Within the framework of the model of the extragalactic background created earlier by the authors, the factors influencing the statistical properties of the confusion noise have...     

Catalog of Supermassive Black Holes for Interferometric Observations

The paper presents a catalog of supermassive black holes (SMBHs) sharpened for interferometric observations at millimeter and submillimeter wavelengths, based on open sources. The catalog includes the object’s name, coordinates, angular size, and mass, the angular size of the gravitational radius of the SMBH, and the integrated radio flux associated with the radiosource concluding the SMBH at 20?900 GHz, planned for the Event Horizon Telescope, the future space mission Millimetron, and others. The catalog is intended for use during planning of interferometric observations of SMBH shadows.

     

The population of cosmic voids

We consider the main population of cosmic voids in a heirarchical clustering model. Based on the Press-Schechter formalism modified for regions in the Universe with reduced or enhanced matter densities, we construct the mass functions for gravitationally bound objects of dark matter occupying voids or superclusters. We show that the halo mass functions in voids and superclusters differ substantially. In particular, the spatial density of massive (M ～ 10¹² M _⊙) halos is appreciably lower in voids than in superclusters, with the difference in the mass functions being greater for larger masses. According to our computations, an appreciable fraction of the mass of matter in voids should be preserved to the present epoch in the form of primordial gravitationally bound objects (POs) with modest masses (to 10% for M _PO < 10⁹ M _⊙) keeping baryons. These primordial objects represent “primary blocks” in the heirarchical clustering model. We argue that the oldest globular clusters in the central regions of massive galaxies are the stellar remnants of these primordial objects: they can form in molecular clouds in these objects, only later being captured in the central regions of massive galaxies in the process of gravitational clustering. Primordial objects in voids can be observed as weak dwarf galaxies or Lyα absorption systems.     

Analytical approximation for the Fe <Emphasis Type="Italic">K</Emphasis><Subscript>α</Subscript> emission line in quasar spectra

The spectra of many Seyfert galaxies display broad Fe K _α emission. The line profile has two maxima, suggesting that the line emerges in the innermost regions of an accretion disk around a black hole, making it necessary to take into account general relativistic (GR) effects. Identifying GR processes occuring in active galactic nuclei (AGN) requires reconstructing the parameters of the accreting system from the line profile using some reasonably quick algorithm. We present here a numerical approximation for the Fe K _α emission line using analytical functions. The approximation encompasses a range of the disk radial coordinate r and the angle θ between the line of sight and the disk normal, and makes it possible to decrease the computing time by six orders of magnitude in certain astrophysical problems, while taking into account all GR effects. Results of the approximation are available at http://www.iki.rssi.ru/people/repin/approx.     

Generalized inflation with a gravitational wave background

We propose a -inflation model that explains a significant part of the COBE signal by primordial cosmic gravitational waves. The primordial density perturbations fulfil both the constraints of large-scale microwave background and galaxy cluster normalization. The model is tested against the galaxy cluster power spectrum and the high-multipole angular cosmic microwave background anisotropy.     

Absence of a periodic component in the quasar z distribution

The presence of a periodic component in the quasar distribution over redshift z is investigated. The periodicity is analysed for the coordinate ln(1 + z) and for the geodesic cosmological distance using the SDSS and 2dF catalogs (??85 000 quasars). Four different criteria and the Fourier transform method were used to search for periodicity. The analysis shows an absence of a periodic component in the quasar redshift distribution at any significant confidence level.     

An absolute cosmological-distance scale and the peculiar-velocity field from proper motions of galaxies

We suggest a method for extracting important cosmological information from observational data on galaxy proper motions on the celestial sphere. These data can be used to reconstruct the three-dimensional velocities of galaxies relative to the cosmicmicrowave background (peculiar velocities), and to separate the Hubble and peculiar components of the observed redshifts in a large volume for the first time. As a result, it is possible to determine the Hubble constant accurately and independently using the radial velocities of comparatively close galaxies (up to 50 Mpc), and to determine distances to the galaxies and the mass distribution in the neighborhood of the Local group of galaxies. The proposed task may be solved using the future “Millimetron” space radio interferometer.     

Current status of models with hot and cold dark matter

An analysis of a five-parameter family of cosmological models in a spatially flat Friedmann Universe with a zero Λ term is presented. The five parameters are (1) σ₈, the dispersion of the mass fluctuations in a sphere with radius 8h ^?1 Mpc, where h=H ₀/100 km s^?1 Mpc^?1 and H ₀ is the Hubble constant; (2) n, the slope of the density-perturbation spectrum; (3) Ω_v, the normalized energy density of hot dark matter; (4) Ω_b, the baryon density; and (5) h, the normalized Hubble constant. The density of cold dark matter is determined from the condition Ω _cdm >1?Ω_v?Ω _b . Analysis of the models is based on comparison of computational results with observational data for: (1) the number density and mass function of galaxy clusters (a so-called Press-Schechter formalism) and (2) the cosmic microwave background anisotropy. The first method enabled us to determine the value σ₈=0.52±0.01 with high accuracy. Using the resulting normalization of the density-perturbation spectrum, we calculated a model for the anisotropy of the cosmic microwave background radiation on large scales (l?10, where l is the harmonic number) and the required contribution of cosmological gravitational waves, characterized by the parameter T/S. The restrictions on T/S become weaker as Ω_v increases. Nevertheless, even when Ω_v≤0.4, models with h+n≥1.5 require a considerable contribution from gravitational waves: T/S?0.3. On the other hand, in models with Ω_v≤0.4 and a scale-invariant density-perturbation spectrum (n=1), we find T/S ?10(h?0.47). The minimization of T/S is possible only for the family of models with red spectra (n<1) and small h (<0.6). The value of Ω_v is determined most accurately by the data onΔT/T near the first acoustic peak (l?200). By imposing a general restriction on the amplitude of gravitational waves T/S∈[0, 3] and taking into account the available observational data on the amplitude of the acoustic peak of Sakharov oscillations, ranges of possible values n and Ω_v are derived. If the baryon number is constrained by nucleosynthesis data, the models under consideration can have both moderately red and blue power spectra n∈[0.9, 1.2] with a rather high concentration of hot particles Ω_v∈[0.2,0.4]. The conditions that n<0.9 and/or Ω_v<0.2 decrease the relative amplitude of the acoustic peak by over 30% compared to its value in the standard cold-dark-matter (CDM) model normalized using COBE data.