Dark Matter and Cosmic Web Story

by Jaan Einasto

  Advanced Series in Astrohysics and Cosmology

  ISSN: 1793-1312

  Series Editor:

  Remo Ruffini (ICRA, Pescara & University of Rome “La Sapienza”, Italy)

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  Accretion: A Collection of Influential Papers

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  by A Ashtekar, Notes prepared in collaboration with R S Tate

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  Hawking on the Big Bang and Black Holes

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  Exploring the Universe: A Festschrift in Honor of Ricardo Giacconi

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  Dark Matter and Cosmic Web Story

  by J Einasto

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  Advanced Series in Astrophysics and Cosmology – Vol. 14 Series Editors: Fang Li Zhi & Remo Ruffini

  Jaan Einasto

  Tartu Observatory, Estonia

  World Scientific

  NEW JERSEY • LONDON • SINGAPORE • BEIJING • SHANGHAI • HONG KONG • TAIPEI • CHENNAI

  Published by

  World Scientific Publishing Co. Pte. Ltd.

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  Library of Congress Cataloging-in-Publication Data

  Einasto, Jaan, author.

  Dark matter and cosmic web story/Jaan Einasto.

  pages cm -- (Advanced series in astrophysics and cosmology; Volume 14)

  Includes bibliographical references and index.

  ISBN 978-9814551045 (hardcover: alk. paper)

  1. Inflationary universe. 2. Cosmology. 3. Dark matter (Astronomy) 4. Astronomers--Estonia-- Social conditions--20th century. I. Title. II. Series: Advanced series in astrophysics and cosmology; Volume 14.

  QB991.I54E36 2013

  523.1'126--dc23

  2013035528

  British Library Cataloguing-in-Publication Data

  A catalogue record for this book is available from the British Library.

  Copyright © 2014 by World Scientific Publishing Co. Pte. Ltd.

  All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the publisher.

  For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher.

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  To Liia with love and thanks

  Preface

  The 20th century has been a golden time for astrophysics and cosmology. An excellent discussion of the development of modern astrophysics and cosmology is given by Longair (2006). The search for dark matter has been a part of this development. The history of the discovery of dark matter and its physical nature have been discussed in numerous conferences and books: Faber & Gallagher (1979), Sanders (2010), Trimble (1987, 1988a,b,c, 1990, 1995, 2010), and van den Bergh (1999, 2001), to mention only the most important sources.

  A personal view of the development of modern cosmology was recently published by Peebles (2012), see also a collection of views of other leading cosmologists, collected by Peebles et al. (2009). Such personal views are extremely interesting to read.

  In this book I try to present a discussion of the Dark Matter Story as seen from my perspective. The work done elsewhere is described in less detail, since I am not familiar with the ‘kitchen’ aspects of these studies. I try to give balanced credit to results of other investigators when the topic is related to our studies. Our attempts to understand the dark matter problem brought us to the study of Large Scale Structure in the Universe. I shall describe the history of the development of these two topics. They are related because dark matter is the dominant population in the Universe and properties of dark matter particles determine details of the structure. In preparing of this book I used my previous reviews of the history of studies of dark matter and large scale structure of the Universe (Einasto, 2001a,b, 2005, 2009).

  The first steps in the search, which ultimately led us to the understanding of the dark matter problem, were made by the founder of the modern Tartu astrophysics school, Ernst Öpik, and his student Grigori Kuzmin, my first mentor. This search has been continued by the present generation of astronomers. The whole group of galactic and cosmology studies of Tartu Observatory participated in this search. I thank all of them: Heino Eelsalu, Maret Einasto, Mirt Gramann, Urmas Haud, Jaak Jaaniste, Mihkel Jõeveer, Lev Kofman, Sergei Kutuzov, Grigori Kuzmin, Dmitry Pogosyan, Enn Saar, Erik Tago, and Peeter Tenjes, and the younger generation of astronomers Gert Hütsi, Lauri Juhan Liivamägi, Ivan Suhhonenko, Antti Tamm, and Elmo Tempel.

  During the search we had many contacts with astronomers in other centres. The first and longest contacts were with Viktor Ambartsumian, Evgeny Kharadze, Kirill Ogorodnikov, and Pavel Parenago. We collaborated closely with Yakov Zeldovich and his team, including Andrei Doroshkevich, Anatoly Klypin, Igor Novikov, Sergey Shandarin, and Rashid Sunyaev. This played a very important role in our studies, as well as our collaboration with Arthur Chernin, Igor Karachentsev, Andrei Linde, Josif Shklovsky, Alexei Starobinsky, and many others.

  I benefitted from contacts with astronomers from other countries. The most fruitful collaboration was with John Huchra. In studying the problems of dark matter and the structure of galaxies and Universe I had discussions with George Abell, Heinz Andernach, Neta and John Bahcall, Ed Bertschinger, Peter Brosche, Margaret and Geoffrey Burbidge, George Contopoulos, Gerard de Vaucouleurs, Margaret Geller, Wilhelm Gliese, Bernard Jones, Rocky Kolb, Dave Latham, Donald Lynden-Bell, Vicent Martinez, Dick Miller, Volker Muller, Jan Henrik Oort, Jerry Ostriker, Changbom Park, Jim Peebles, Luboŝ Perek, Joel Primack, Martin Rees, Mort Roberts, Vera Rubin, Remo Ruffini, Alex Szalay, Gustav Andreas Tammann, Beatrice Tinsley, Alar Toomre, Virginia Trimble, Sidney van den Bergh, Rien van de Weygaert, Simon White, and many others. My sincere thanks to all my friends and colleagues — interactions with them helped to develop the present concept of dark matter and large scale structure of the Universe.

  My special thanks to my family for support and practical help. My wife Liia and daughter Maret participated in this study in many ways; my grandchildren Peeter, Triin and Stiina helped in
the preparation of the book. I thank Changbom Park, Remo Ruffini, Mikk Sarv, Rein Taagepera, Virginia Trimble, and Rien van de Weygaert for suggestions made after reading preliminary versions of the book. Many thanks to the editors of the book Roh-Suan Tung and Lerh Feng Low.

  The book is accompanied by a website which contains additional material: copies of originals of some crucial papers, astronomical movies, and also movies which show our life.1

  1 http://www.aai.ee/~einasto/DarkMatter

  Contents

  Preface

  1.Prologue

  2.Classical cosmological paradigm

  2.1Astronomy in the first half of the 20th century

  2.1.1The nature of spiral nebulae

  2.1.2The expansion and age of the Universe

  2.1.3The mean density of matter in the Universe

  2.1.4The distribution of galaxies

  2.1.5Structure of the system of stellar populations

  2.1.6The evolution of stars

  2.2History of Estonia, my family roots, and Tartu Observatory

  2.2.1A short history of Estonia

  2.2.2My roots

  2.2.3My early life and first steps in astronomy

  2.2.4Liia

  2.2.5Tartu Observatory after the war, and the building of the new observatory

  3.Galactic models and dark matter in the solar vicinity

  3.1Early Galactic models

  3.1.1Early Galactic models and first hints of the presence of dark matter

  3.1.2Density of matter in the Solar vicinity

  3.1.3Galactic models by Parenago, Kuzmin, and Schmidt

  3.2New Galactic models

  3.2.1Search for better models

  3.2.2Generalised exponential model

  3.2.3Our Galaxy, system of galactic constants

  3.2.4Mass-to-luminosity ratios of stellar populations

  3.2.5Evolution of galaxies3.2.6 Models of galaxies of the local group and M87; mass paradox in galaxies

  3.3Tartu Observatory in the 1960’s

  3.3.1New observatory

  3.3.2Philosophical seminars and New Year parties

  3.3.3Space studies

  4.Global dark matter

  4.1The discovery of global dark matter

  4.1.1Galactic coronas

  4.1.2Clusters and groups of galaxies

  4.1.3Dynamics and morphology of companion galaxies

  4.1.4Tallinn and Tbilisi dark matter discussions

  4.2The confirmation of the presence of global dark matter

  4.2.1Rotation curves of galaxies

  4.2.2Mass-to-luminosity ratios of galaxies

  4.2.3X-ray data

  4.2.4Gravitational lensing

  4.3Dark matter in galaxies

  4.3.1The density distribution of dark matter

  4.3.2Distribution of luminous and dark matter in galaxies.

  4.3.3Universal rotation curve of galaxies

  4.3.4The formation of galaxies

  4.3.5Modern models of galaxies

  4.4Tartu Observatory in the 1970’s

  4.4.1Computer revolution

  4.4.2Life in the Observatory

  5.The cosmic web

  5.1Early studies of spatial distribution of galaxies

  5.2The discovery of the cosmic web

  5.2.1Zeldovich question

  5.2.2The Tallinn symposium on large scale structure of the Universe

  5.2.3Superclusters, filaments and voids

  5.3Tartu Observatory in the early 1980’s

  5.3.1Southern base of Tartu Observatory

  5.3.2Studies of ancient astronomy

  6.The nature of dark matter

  6.1Baryonic dark matter

  6.1.1Early discussions on the nature of dark matter

  6.1.2Stellar or gaseous dark coronae

  6.1.3Nucleosynthesis constraints of baryonic matter

  6.2Non-baryonic dark matter

  6.2.1Cosmic microwave background radiation

  6.2.2Fluctuations of the CMB radiation

  6.2.3Neutrinos as dark matter candidates

  6.2.4Cold dark matter

  6.2.5Dark matter in dwarf galaxies

  6.2.6Missing satellite problem and warm dark matter

  6.2.7Searches for dark matter particles

  6.3Alternatives to dark matter

  6.4Tartu Observatory in the late 1980’s

  6.4.1The singing revolution

  6.4.2Academy of Sciences

  6.4.3Towards an independent Estonia

  7.The structure of the cosmic web

  7.1Quantitative characteristics

  7.1.1The search for quantitative characteristics

  7.1.2Topology of the cosmic web

  7.1.3Fractal properties of the cosmic web

  7.1.4Physical biasing

  7.1.5Power spectra of galaxies

  7.2Redshift surveys and catalogues

  7.2.1Redshift surveys

  7.2.2Catalogues of groups and clusters of galaxies

  7.2.3Catalogues of superclusters

  7.3Elements of the cosmic web

  7.3.1Galaxies in different environments

  7.3.2Groups and clusters of galaxies

  7.3.3Chains, strings and filaments

  7.3.4Walls

  7.3.5Superclusters

  7.3.6Voids and supervoids

  7.3.7Cosmic web — cells and the cosmic foam

  7.3.8Regularity of the cosmic web

  7.3.9Baryonic acoustic oscillations

  7.4Tartu Observatory in the 1990’s

  7.4.1Estonian path to independence

  7.4.2Science reform

  7.4.3Participation in international organisations

  8.Cosmic inflation, dark energy and the evolution of the Universe

  8.1The birth of the Universe and inflation

  8.1.1The classical inflation theory

  8.1.2The new inflation theory and the birth of the Universe.

  8.2Structure formation in Hot, Cold and Lambda models

  8.2.1Initial conditions

  8.2.2HDM and CDM simulations

  8.2.3Simulations with cosmological constant

  8.2.4Modern cosmological simulations

  8.3The formation and evolution of the cosmic web

  8.3.1The luminosity density field of the SDSS

  8.3.2The role of density waves of various scales

  8.3.3The phase coupling of density perturbations of various scale

  8.3.4The fine structure of the cosmic web

  8.4Dark energy

  8.4.1The discovery of dark energy

  8.4.2The role of dark energy in the evolution of the Universe

  8.4.3Cosmological parameters

  8.4.4New cosmology paradigm is ready: What next?

  8.5Remembering contacts with colleagues

  8.5.1Encounters with astronomers from other centres

  8.5.2Collaboration with other centres

  8.6Tartu Observatory and my life in the 2000’s

  8.6.1Transition years

  8.6.2Center of Excellence

  8.6.3Egeri

  9.Epilogue

  Bibliography

  General Index

  Name Index

  Chapter 1

  Prologue

  Once I happened to read Thomas Kuhn’s book The Structure of Scientific Revolutions (Kuhn, 1970). It was in mid 1970’s, and the presence of dark matter in galaxies had just been reported. The discussion between supporters and opponents of the dark matter concept was at its peak. Then I realised that the dark matter story seems to be a good example of a scientific revolution. Ten years later, in concluding remarks of the IAU Symposium on “Dark Matter in the Universe”, Scott Tremaine also pointed to the development of the dark matter concept as a classic example of a scientific revolution (Tremaine, 1987), see also Binney & Tremaine (1987)).

  In the present book I shall give a personal view of the study of dark matter and large scale structure of the Universe. There are not so many areas in modern astronomy where the development of ideas can be descri
bed in terms of paradigm changes, thus I shall discuss the dark matter story from this point of view. Tartu astronomers have participated in the study of dark matter for a long time, starting from Ernst Öpik—the founder of the contemporary astronomy school in Estonia— and followed by Grigori Kuzmin, his most talented student. The present generation of astronomers has continued the investigation of dark matter. Unexpectedly, this work led us to study the distribution of galaxies and clusters on large scales and peaked with the discovery of the cosmic web with voids and filaments. I hope that our story is of interest to the cosmology and perhaps also to the physics community, as some aspects of it have yet to be well documented.

  First I give a short review of the classical world view on galaxies and the Universe, as it was when I started as a young scientist my work in Tartu Observatory. The astronomical community and, in particular, my mentors Prof. Taavet Rootsmäe and Grigori Kuzmin in Tartu, and Prof. Pavel Parenago in Moscow had certain views on the structure of galaxies and the Universe. This was the background when I started my studies.

  Kuzmin and Parenago developed methods to calculate models of galaxies, and Rootsmäe and Parenago investigated properties of stellar populations. These topics were earlier considered as separate tasks. I saw a possibility to combine both approaches, and to construct models of galaxies, where all possible data on galactic populations are taken into account. This was my first goal. To my surprise I encountered here difficulties, which ultimately led to the discovery of a controversy in data, discussed in detail in Chapter 3. This was our first step towards the development of a new paradigm on the structure of galaxies.

  In our attempts to solve the controversy in the structure of galaxies we found that it is not possible to consider galaxies as isolated systems — the environment of the galaxies is also important. We found that galaxies are surrounded by dark massive coronas of unknown origin and nature. This was the second step in our journey towards the solution of the controversy in the understanding of the structure of galaxies.