The National Library of Argentina: exhibiting astronomy-related rare books

Astronomical and cosmological knowledge up to the dawn of modern science was profoundly embedded in myth, religion and superstition. Many of these inventions of the human mind remain today stored in different supports: medieval engravings, illuminated manuscripts, and of course also in old and rare books.Comment: to appear in The Role of Astronomy in Society and Culture: Proceedings of the IAU Symposium 260, D. Valls-Gabaud and A. Boksenberg (eds), Cambridge: Cambridge University Press, IAU Symposia Serie

Cosmology from Topological Defects

The potential role of cosmic topological defects has raised interest in the astrophysical community for many years now. In this set of notes, we give an introduction to the subject of cosmic topological defects and some of their possible observable signatures. We begin with a review of the basics of general defect formation and evolution, we briefly comment on some general features of conducting cosmic strings and vorton formation, as well as on the possible role of defects as dark energy, to end up with cosmic structure formation from defects and some specific imprints in the cosmic microwave background radiation from simulated cosmic strings. A detailed, pedagogical explanation of the mechanism underlying the tiny level of polarization discovered in the cosmic microwave background by the DASI collaboration (and recently confirmed by WMAP) is also given, and a first rough comparison with some predictions from defects is provided.Comment: Lecture Notes delivered at the Xth Brazilian School on Cosmology and Gravitation, Mangaratiba, Rio de Janeiro, July 29 - August 9, 2002. To appear in the proceedings (AIP Press), edited by M. Novello and S. Perez Bergliaffa. Updated source files with high resolution figures available at http://www.iafe.uba.ar/relatividad/gangui/xescola

In Support of Inflation

The cosmic microwave background (CMB) provides a snapshot of the early Universe when matter began to become structured and has been the focus of several recent observational campaigns. In this Perspective, we discuss the results from these campaigns, which provide support for inflationary models of the Universe.Comment: Perspective: Cosmology. See summary at http://www.sciencemag.org/cgi/content/summary/291/5505/837 (need sign up) or full text (free) at http://www.iafe.uba.ar/relatividad/gangui

A Preposterous Universe

Recent announcements that the Cosmic Microwave Background (CMB) - the faint remnant of the Big Bang - is polarized have caused a stir among cosmologists. Such polarization has long been predicted but could not be detected, until the recent DASI and WMAP detections. The polarization is a signature of the motion of the primordial seeds that led to the galaxies and large-scale structure of the Universe observed today. Earlier measurements of tiny temperature fluctuations in the CMB have been used to infer the sizes of the primordial seeds. The polarization signature should help to determine the fundamental parameters of cosmology and to explain how large-scale structure arose [Highwire abstract].Comment: Perspective: Astronomy. See summary at http://www.sciencemag.org/cgi/content/summary/299/5611/1333 (need sign up) or full text (free) at http://www.iafe.uba.ar/relatividad/gangui

Early Universe Sources for Cosmic Microwave Background Non-Gaussianity

In the framework of inflationary models with non-vacuum initial states for cosmological perturbations, we study non-Gaussian signatures on the cosmic microwave background radiation produced by a broken-scale-invariant model which incorporates a feature at a privileged scale in the primordial power spectrum.Comment: Contribution to the "Fifth Alexander Friedmann International Seminar on Gravitation and Cosmology", Joao Pessoa, Brazil, 200

Primordial Non-Gaussian Signatures in the Sky

The presence of non-Gaussian features in the CMB radiation maps represents one of the most long-awaited clues in the search for the actual structure of the primordial radiation. These features could shed some light on the non trivial task of distinguishing the real source of the primeval perturbations leading to large scale structure. In the present paper we briefly review recent work towards finding analytical estimates of the three- and four-point correlation functions and of their zero-lag limits, namely, the skewness and kurtosis, respectively. - Contributed talk to appear in the proceedings of "Birth of the Universe & Fundamental Physics", May 18-21, 1994, Rome, Italy.Comment: 4pp; PostScript fil

Some remarks on a current study involving preservice elementary teachers and some basic astronomical phenomena

Recent studies have shown that not only primary school students but also their future teachers reach science courses with pre-constructed and consistent models of the world surrounding them. These ideas include many misconceptions which turn out to be robust and hence make difficult an appropriate teaching-learning process. We have designed some tools that proved helpful in putting in evidence some of the most frequently used alternative models on a few basic astronomical notions. We have tested these tools with preservice elementary teachers from various normal schools in Buenos Aires and made a first analysis of the results. The collection of data recovered so far shows that some non-scientific conceptions are indeed part of the prospective teachers' (scientific) background and that, therefore, the issue deserves special attention during their formal training.Comment: to appear in The Role of Astronomy in Society and Culture: Proceedings of the IAU Symposium 260, D. Valls-Gabaud and A. Boksenberg (eds), Cambridge: Cambridge University Press, IAU Symposia Serie