Narrow Results

Here, we briefly discuss the possibility to solve simultaneously with primordial black holes (PBHs) the problems of dark matter (DM), reionization of the universe, origin of positron line from Galactic center and supermassive black hole (BH) in it. Discussed scenario can naturally lead to a multiple-peak broad-mass-range distribution of PBHs in mass, which is necessary for simultaneous solution of the problems.

Primordial black holes (PBHs) could account for variety of phenomena like dark matter, reionization of the universe, early quasars, coalescence of black holes registered through gravitational waves recently. Each phenomenon relates to PBH of a specific mass range. PBH mass spectra varies in a wide range depending on specific model. Earlier, we have shown that PBH with monochromatic mass distribution around $5\times 10^{16}$ g value allow to re-ionize the universe moderately. Here, we show that reionization effect and contribution to dark matter can be simultaneously enhanced with more natural extended mass distribution in the range around the same mass value.

We present the first results obtained in the elaboration of a complete model of a microquasar where the donor star is from Population III. These stars do not produce stellar winds so we consider that the mass loss is due exclusively to matter overflowing the Roche lobe towards the compact object, a maximally rotating black hole. The rate of accretion is extremely super-Eddington, with an intense mass loss from the system in the form of winds and jets. We calculate the relativistic particle content of the jet and the corresponding spectral energy distribution (SED) considering a lepto-hadronic model. Prospects for the cosmological implications of these objects are briefly discussed.

Inflation predicts primordial scalar perturbations with a nearly scale-invariant spectrum and a spectral index approximately unity (the Harrison–Zel'dovich (HZ) spectrum). The first important step for inflationary cosmology is to check the consistency of the HZ primordial spectrum with current observations. Recent analyses have claimed that a HZ primordial spectrum is excluded at more than 99% c.l. Here we show that the HZ spectrum is only marginally disfavored if one considers a more general reionization scenario. Data from the Planck mission will settle the issue.

We introduce Probing Radio Intensity at high-Z from Marion (PRI^ZM), a new experiment designed to measure the globally averaged sky brightness, including the expected redshifted 21cm neutral hydrogen absorption feature arising from the formation of the first stars. PRI^ZM consists of two dual-polarization antennas operating at central frequencies of 70 and 100MHz, and the experiment is located on Marion Island in the sub-Antarctic. We describe the initial design and configuration of the PRI^ZM instrument that was installed in 2017, and we present preliminary data that demonstrate that Marion Island offers an exceptionally clean observing environment, with essentially no visible contamination within the FM band.

The boosting effects induced by the peculiar motion of an observer with respect to the Cosmic Microwave Background (CMB) rest frame can be explored to analyze the frequency dependence of the dipole. The improvements achievable with future CMB missions on our knowledge of CMB spectral distortions and Cosmic Infrared Background spectrum are discussed considering realistic uncertainties in relative calibration and foreground subtraction.

The Square Kilometre Array (SKA) is a new technology (large array) radio-telescope that, owing to its extremely high sensitivity and resolution, will allow to investigate different cosmological and astrophysical topics. In this work, we discuss the possible contribution of the SKA in combination with future cosmic microwave background experiments in probing various types of dissipation processes relevant at different cosmic epochs.

This volume assumes pre-requisite knowledge of basic cosmology and of standard methods of mathematical physics. This chapter presents just a brief review of essential elements of the expansion history of the Universe (more exhaustive expositions are available in standard textbooks such as those cited in the previous chapter).