THE COSMIC BACKGROUND RADIATION
A NATO Advanced Study Institute
Strasbourg 1996
Observatoire astronomique de Strasbourg
May 27, 1996 - June 7, 1996
A NATO Advanced Study Institute
Strasbourg 1996
May 27, 1996 - June 7, 1996
General Information
Scientific Program
Accommodations
Registration
Scientific Committee
Local Organizing Committee
This Advanced Study Institute is sponsored by
NATO. The directors are:
The relic Cosmic Background Radiation (CBR)
carries information on the physical conditions
prevailing during the early phases of cosmic expansion, and
thus represents an invaluable tool for reconstructing
the general history of the Universe, and for the construction
of a detailed model of galaxy formation. Access to this
information is obtained through studies of the spectrum
of the background and of the spatial distribution of its effective
temperature on the sky. Due to technical difficulties associated
with observations at millimeter wavelengths and because of the
high precision required to detect the temperature fluctuations,
it is only recently, within the last couple of years, that the
full potential of this tool has been realized.
Activity in the field has increased dramatically
since the first detection of anisotropies by COBE, with
several groups now reporting detections on a variety of
angular scales. The MIT balloon experiment has announced
a positive cross-correlation with the COBE maps, offering
a confirmation of the detection.
These new data together with the recently released
four year COBE maps will provide an opportunity
to summarize the situation on large angular scales,
and to discuss the possible existence of nongaussianity
in the perturbation statistics, a prediction of
several models.
In addition, many experiments searching for the
perturbations on degree scales are beginning to report
interesting results, although often in conflict with
one another. These intermediate
scales are important as one can gain information
on various cosmological parameters (like the Hubble constant,
the density parameter, the cosmological constant, the baryonic content
of the universe, ..) and on the ionization history of the Universe subsequent
to the standard epoch of recombination. Many
in-depth studies of the numerous effects of
reionization are beginning to produce definitive
results. Such scales also approach those directly
observed in the galaxy
distribution today, permitting a direct comparison
of the initial conditions of the density field
with the result of 10 billion years of evolution. One of
the important goals of the school will be to
attempt to sort out the rather confusing state of
affairs currently prevailing on these scales.
Significant progress has also been made
on even smaller scales, where new instruments and
techniques are just coming into operation. This includes,
for example, the development of bolometer arrays
operating at millimeter and sub-millimeter wavelengths
and the dedication of the Ryle Telescope to CMB studies.
On these smaller scales, the CMB perturbations
are influenced by radio emissions of galaxies and
by the Sunyaev-Zel'dovich effect operating in
galaxy clusters. In particular, the modeling of
this latter effect offers the opportunity to
study the evolution of structure formation to
large redshifts, permitting the detection of
early clusters if they exist. As the rate
of structure formation is governed by the universal
mean density, one can constrain this all important
parameter, as has been attempted recently
by several authors. An important topic for
the school will be the discussion of these new
detectors and their potential in the coming years.
This will aid the definition of the mission goals
for currently planned experiments such as
COBRAS/SAMBA and MAP
Any cosmological interpretation of measured
CMB perturbations depends upon reliable understanding
and removal of possible sources of Galactic contamination.
Thanks to the wide spectral coverage of COBE, models
of Galactic emissions have greatly improved,
and this will form one of the main topics of the school,
together with discussions of the proper statistical treatment
of noisy data in the presence of such foreground
influences.
The spectrum of the CMB fossilizes the thermal
history of the Universe from as early an epoch as 1 year
after the beginning until the present. Limits on
spectral distortions from a pure blackbody spectrum
translate directly into constraints on the amount of
energy release permissible during the expansion.
This is especially important for models postulating
a period of reionization, as some results of degree
scale experiments may demand. The most recent limit
from COBE represents an improvement of one order of
magnitude, the implications of which will form one
of the focal points of the school.
Cosmic Background Radiation 96
Observatoire de Strasbourg
11 rue de l'Université
67000 Strasbourg
Fax : (33) 88 25 01 60
e-mail : cbR96@astro.u-strasbg.fr
DEADLINE FOR REGISTRATION : April 25th, 1996
The Cosmic Background Radiation 96
Cosmic Background Radiation 96
NATO ASI CBR96
Observatoire Astronomique
11, rue de l'Université
67000 STRASBOURG
FRANCE
Fax: +33-88 25 01 60
E-mail: cbr96@astro.u-strasbg.fr
cbr96@astro.u-strasbg.fr
A. Blanchard
Observatoire astronomique de Strasbourg
France
B. Jones
The structure we observe in the Universe today is though to have arisen by the action of gravitational forces on an initial state that differed slightly and randomly from the idealised homogeneous and isotropic world models of Relatvistic Cosmology. The theory of random functions plays an important dual role in the study of cosmic structure: it provides us with the tools necessary to provide a full description of this initial state, and it provides us with the tools to analyse the present state. In these lectures I present a fairly rigorous discussion of random fields: how to describe them, how they respond to forces and how organised structures can emerge. This provides the basis for statistical analysis of random fields: counts-in-cells, correlation functions, Weiner filters, Power Spectral analysis and so on. I then apply this to specific examples such as the problems of determining the mean density of the Universe and of calculating correlation functions from selected samples, and to the analysis of cosmic microwave background fluctuations.
R. B. Partridge
Haverford College
Haverford PA USA
These two lectures are intended to introduce some of the observational techniques used to study the cosmic microwave background radiation (CBR), to list some recent observational results, especially on CBR anisotropies, and to examine the implications of these results for cosmology and theories of astrophysical structure formation. In the first lecture, I will first introduce the observation techniques now standard in the field, then emphasize potential observational problems and uncertainties, sources of noise and possible systematic errors in measurements of the temperature of the CBR and its angular distribution on the sky. In the second lecture, I will try to project the status of observational programs that will produce results over the next few years, while we wait for the next CBR satellite mission. I will then go on to outline briefly some of the links between these observations and theory. The emphasis will be on the physical understanding of these links, not on the mathematical details, which I expect other lecturers will take up. I hope to have the time to look specifically at secondary fluctuations (CBR anisotropies introduced at much later epochs than recombination).
Some suggested reading:
For lecture 1 --
Section I of CMB ANISOTROPIES TWO YEARS AFTER COBE, ed L. M. Krauss,
World Scientific, Singapore (1995)
Section 4 of White, Scott and Silk, Ann. Rev. Astron & Astrophys. 32, p.
319 (1994)
Chapters 2, 3, 4, 6 and 7 of #K: THE COSMIC MICROWAVE BACKGROUND
RADIATION, R. B. Partridge, Cambridge Univ. Press (1995).
For lecture 2 --
White et al., op cit
Chapters 5 and 8, Partridge, op cit
Rephaeli, Ann. Rev. Astron. & Astrophys. 33, p. 541 (1995).
J.-L. Sanz
Santander, Spain
Lecture 1: Basic General Relativity
The Equivalence and Covariance Principles. The metric, the Riemmann and the
Weyl tensors. Geodesics. The energy-momentum tensor. The Einstein equations.
Kinematics.
Lecture 2: Basic Cosmology
The redshift. Luminosities, distances and magnitudes. The Cosmological
Principle. The Friedmann-Robertson-Walker model. The big-bang and the
inflationary paradigm.
Lecture 3: Basic Cosmic Microwave Background
Geodesics on the FRW background. Spectrum and Anisotropies after COBE. Basic
on perturbation theory and gauge invariance. Geodesics in the potential
approximation. The Sachs-Wolfe effect.
We pretend with this 3 lectures (1.5 hours each one) to give an elementary introduction to General Relativity, Cosmology and the Cosmic Microwave Background. The presentation will be schematic, making emphasis on those aspects of General Relativity that are of interest in Cosmology and, in particular, to the Cosmic Microwave Background.
G.Smoot
Lawrence Berkeley Laboratory
Berkeley, USA
1. The Cosmic Microwave Background Radiation - Introduction to the CMBR in terms of intensity and anisotropy (DTa/DT) spectrum, foregrounds, measurement and brief history of early observations ending with a summary of the knowledge as of early 1992. I will also discuss the theory of intensity (temperature) spectral distortions.
2.& 3. COBE observations of the CMBR. These two lecture gives the details of the COBE instrumentation, observations, results and some interpretation of the COBE results and lessons learned and implication for future observations.
4. Current and Future CMBR Anisotropy Observations - This lecture (and part of lecture 3) will summarize current results and discuss the technology and capability of future observations - what observations can be expected from suborbital platforms and the capabilities of the space missions: MAP and COBRAS/SAMBA (I am assuming that COBRAS/SAMBA will be selected.)
References: G.F. Smoot (UCB/LBL) and D. Scott (UBC), astro-ph/9603157.
A.Stebbins
Fermi National Accelerator Laboratory
Chicago, USA
The cosmic microwave background radiation (CMBR) provides us with one of our most sensitive probes of the universe. Small anisotropies in the CMBR brightness have been observed providing an important measure of the inhomogneities in the universe on the largest accessible scale. Measurements of the CMBR proposed for the next 5-10 years should be able to make a definitive determination on whether the inhomogeneities were initially adiabatic or isocurvature (e.g. inflation vs. topological defects); to make independent determinations of cosmological parameters such as the $\Omega_0$, $H_0$, $\Lambda$, and $\Omega_\rmb$; and even be able to determine whether any neutrino species have a moderate mass of a few eV. In these lectures I will discuss why and how one can infer all of these things from anisotropy measurements.
Michael S. Turner
The University of Chicago and Fermi National Accelerator Laboratory
Chicago, USA
In these two lectures I will lay out the basics of inflation,
review the different particle physics models of inflation,
discuss the fundamental predictions
of inflation, and emphasize the important role that CBR anisotropy
plays in testing the inflationary paradigm. I will pay particular
attention to the relationship between the inflationary potential
and the spectral indices and relative amplitudes of the scalar and
tensor perturbations, and how a high-resolution map of the CBR sky
can be used to infer properties of the inflationary potential as
well as test the consistent of inflation.
Finally, I will briefly discuss the implications of inflation
for structure formation and give my appraisal of the CDM family of models --
LHCCDM, $\nu$CDM, $\tau$CDM, TCDM, and $\Lambda$CDM.