Catálogo de publicaciones - libros

Spectral Special Fluctuations (SSF) of CMBR temperature as manifestation of protoobjects in Dark Ages epoch are considered. Expected values of ΔT/T are ~ 10–10 and the bandwidth of the lines is 0.1–3% depending on the scale of protoobjects and redshifts. Simulation of the experiment is made for MSRT (Tuorla Observatory, Finland) equipped by a 7×4 beam cryo-microbolometer array with a chopping at and frequency multiplexer providing 7 spectral channels in each beam (88–100 GHz). Expected upper limit of ΔT/T in the experiment is 2 · 10 with angular resolution 6′–7′ that may be enough to detect large scale SSF with = 1200–1500 at = 20–30. Such an experiment sets upper limits of SSF in MM band and allows us to prepare future SSF observations.

The Antimatter Magnetic Spectrometer (AMS) is a particle physics experiment designed to operate in space. AMS consists of a magnetic spectrometer, equipped with several sub-detectors which provide a very precise particle identification as well as redundant measurement of its energy, velocity and electric charge.

Understanding the nature of dark energy is one of the most important quests in modern cosmology and fundamental physics. Observations of galaxy clusters at low and high redshifts can be used to place constraints on the equation of state of dark energy and its evolution. Here, we briefly illustrate an ongoing project to constrain dark energy using state-of-the-art X-ray and optical observatories.

ASTRAL is a project incorporating wide-field optical telescopes on board a small satellite (FedSat or SMEX type) dedicated to the whole-sky detection of a variety of rapid astronomical phenomena, particularly optical flashes associated with gamma ray bursts (GRB). Those flashes only visible optically (so called ), as well as those which could precede associated GRBs, cannot be detected in the current triggering mode of the world wide GRB Coordinates Network (GCN). Hence ASTRAL would have a unique opportunity to trigger a follow-up multi-frequency study via GCN. ASTRAL consists of a set of 13 wide-field cameras, each with FOV = 70°, equipped with 4096 × 4096 CCDs. The detection method is based on comparison of sky images with the reference image. Supernovae, novae and nova-like explosions, fast variable AGNs, flare stars, and even new comets would be promptly detected as well. Thus ASTRAL would be an original working prototype of the prospective major space mission to monitor on-line all the sky, a high priority instrument of 21st Century astrophysics. See http://www.atnf.csiro.au/people/Gregory.Tsarevsky for details.

We present an overview of the science case for a 50–100m Extremely Large Telescope. A summary of the potential performance in terms of angular resolution and depth is given. Selected science drivers are then discussed including terrestrial planets in extra-solar systems; stellar populations across the Universe; the first objects and reionization structure of the Universe. Although by no means an exhaustive list, these cases provide examples where an ELT can make a dramatic advance in our understanding of the Universe around us.

We review the properties of Lyman break galaxies at ≥ 5 and use them to explore prospects for observations of such galaxies at = 5, 10 and beyond with 30-100m optical/near-IR ground-based telescopes.

The ATA is a new radio telescope operating at centimeter wavelengths. Its wide field of view and continuous frequency coverage make it an excellent instrument for surveys of both continuum and line sources. I discuss in detail two goals of the ATA in extragalactic science: an HI counterpart to the Sloane Digital Sky Survey; and surveys for transient sources.

Relic radio sources (for the nomenclature see [1]) are extinct or dying active galactic nuclei (AGN). These sources bear importance to the understanding of radio source evolution, in particular to the late phase of exhaustion of the central energy source, the AGN. The few existing candidate sources provide the (almost) unique opportunity to estimate at least the duration of the decline of the lobe brightness, owing to the pronounced spectral steepening which they are characterized by. Another essential condition that features them is the absence of any central source and of any coherent jet structure, both of which would hint at ongoing activity and transport of energy and momentum out into the lobes.

Galaxies (and quasars) hosting active galactic nuclei (AGN) are usually powerful radio sources which produce jets and extended radio emitting regions (lobes) of plasma. There is a huge range from less than 100 pc up to few Mpc in linear extent of the radio galaxies (RGs). RGs with sizes over more than one Mpc represent the biggest single objects in the Universe. The most extreme of those is 3C236 which has a projected linear size of 4.2 Mpc (H =71 km s Mpc, Ω = 1). Another example of a giant radio galaxy (GRG) B0503-286 is shown in Fig. 1. The very large angular sizes (up to several dozens of arcminutes) of GRGs on the sky give an excellent opportunity to study the nature of AGNs and provide important constraints on the evolution of galaxies. Because of their sizes and luminosities GRGs have significant influence on the intergalactic medium (IGM). The total energy delivered into the IGM by the twin jets of a GRG is about 10 J, which is a significant fraction of the gravitational energy released during the formation of a supermassive black hole in the centre of an AGN’s parent galaxy. On the other hand, GRGs possess low equipartition magnetic field strengths and energy densities of their cocoons. This matches the statement of Colgate & Li [1] who affirm that for most radio sources located in a low-density environment only a small fraction of the magnetic energy is dissipated in the form of synchrotron radiation while the bulk of the magnetic energy is deposited in the walls and voids of the Universe. Kronberg et al. [2] suggest that the magnetic energy which originates from AGN outflows and which is stored in the intergalactic magnetic field has a major influence on the evolution of galaxies and visible structure formation on scales of up to ~ 1Mpc.

The low-frequency (< 150 MHz) region is among the most poorly explored of the entire radio spectrum despite the many unique astrophysical questions that can be addressed with observations in these bands. In the framework of our on-going study of the radio continuum spectra of the B3VLA survey we have used observations of Tschager et al. [1] obtained with the VLA in A-array at 74MHz to extend our database towards lower frequencies – with a resolution of about a factor of 3 higher than the upcoming VLA Low-frequency Sky Survey (VLSS, [2]). For about a third of the sample (~ 360 radio sources) we have now 6 or more measurements in the range between 74MHz and 10.5 GHz. This unique frequency coverage allows consistency checks of the new 74MHz flux densities and provides the comparison data to test the influence of various observational effects at such low frequencies. We have performed a spectral analysis to determine particular features like low-frequency turn-overs caused by synchrotron self-absorption or free-free absorption. Some radio sources show extended and complex morphologies not seen at higher frequencies, indicating the presence of diffuse structures with very steep spectra. Our project is an example of a typical application of the future LOFAR telescope in the field of source evolution.