196 research outputs found
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
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
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
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
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