Dark Matter - Jaan Einasto
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2013 January/February AAS Newsletter 31 January, 2013
2013 January/February AAS Newsletter 31 January, 2013 President's Column David J. Helfand Quest University Canada As I noted in my opening remarks at the 221st meeting of the Society in Long Beach, the state of the AAS — unlike that of the nation — is strong. We ended the year with a small positive balance in the Society's account for the fourth year in a row. Our collection of journals — the highest impact journals in the world in our field — is in even stronger financial shape. Our semiannual conferences exceed expected attendance levels every time we meet, and we are exploiting the Executive Office's outstanding meeting organization resources to support more of our Division Meetings and to launch the Topical Conference Series with three smaller, focused meetings this summer. We will have an expanded public policy presence with the recruitment of Joel Parriott to the fulltime role of Director of Public Policy, and our education and public outreach activities continue to grow in size and impact. This enviable position of strength affords us the opportunity to examine many of the things we do for our members to see if we can do them even better. It also allows us to work on some of the issues in our discipline where we face notable challenges in the research funding trajectory, in facilities access, and with employment/demographic issues. In the months ahead, you will see initiatives in several of these areas. The Employment Committee, chaired by Kelle Cruz, has a new Strategic Plan which promises future benefits for our members. -
Pos(Westerbork)002 Historical Introduction Historical S 4.0 International License (CC BY-NC-ND 4.0)
Historical Introduction PoS(Westerbork)002 Richard Strom ASTRON Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands E-mail: [email protected] 50 Years Westerbork Radio Observatory, A Continuing Journey to Discoveries and Innovations Richard Strom, Arnold van Ardenne, Steve Torchinsky (eds) Published with permission of the Netherlands Institute for Radio Astronomy (ASTRON) under the terms of the Creative CommonsAttribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Chapter 1 Historical introduction Richard Strom* rom the English longbows at the battle of Crécy (1346) to Winston Chur- chill’s world war I mobilized cannon (its true identity hidden behind the Fpseudonym “[water] tank”), warfare has always pushed technological innovation to new fronts. The second world war (WWII) was no exception. It gave us technology ranging from the dynamo-powered flashlight (a Philips invention) to jet engines, and space-capable rockets (Germany’s V2), not to mention (in a completely different realm) the mass production of Penicillin. In fact, it could be argued that WWII inventions marked the inception of the modern technological era1. In the field of electronics, the war led to innovations such as radio navigation, aircraft landing systems, and radar. It was these developments which were to * ASTRON, Univer- sity of Amsterdam, have a revolutionary impact on astronomy, initially in Britain, Australia and the The Netherlands United States. But the story begins in the US, with the electronics of the 1920s and ‘30s. Figure 1. Karl G. Jansky (c. 1933) Around 1930, there was increasing interest in the use of radio frequencies for communication. One of the main players, the Bell Telephone Laboratories in New Jersey, asked their research engineer, Karl Jansky (Figure 1), to investigate the inter- ference environment in the “short-wave” band around 20 MHz. -
Radio Astronomy
Theme 8: Beyond the Visible I: radio astronomy Until the turn of the 17th century, astronomical observations relied on the naked eye. For 250 years after this, although astronomical instrumentation made great strides, the radiation being detected was still essentially confined to visible light (Herschel discovered infrared radiation in 1800, and the advent of photography opened up the near ultraviolet, but these had little practical significance). This changed dramatically in the mid-20th century with the advent of radio astronomy. 8.1 Early work: Jansky and Reber The atmosphere is transparent to visible light, but opaque to many other wavelengths. The only other clear “window” of transparency lies in the radio region, between 1 mm and 30 m wavelength. One might expect that the astronomical community would deliberately plan to explore this region, but in fact radio astronomy was born almost accidentally, with little if any involvement of professional astronomers. Karl Jansky (1905−50) was a radio engineer at Bell Telephone. In 1932, while studying the cause of interference on the transatlantic radio-telephone link, he discovered that part of the interference had a periodicity of one sidereal day (23h 56m), and must therefore be coming from an extraterrestrial source. By considering the time at which the interference occurred, Jansky identified the source as the Milky Way. This interesting finding was completely ignored by professional astronomers, and was followed up only by the radio engineer and amateur astronomer Grote Reber (1911−2002). Reber built a modern-looking paraboloid antenna and constructed maps of the radio sky, which also failed to attract significant professional attention. -
Viktor Ambartsumian International Prize 2012 Goes to Prof. Jaan EINASTO (Estonia) and Prof
Viktor Ambartsumian International Prize Steering Committee Official Press-Release, 21.07.2012, Yerevan, Armenia Viktor Ambartsumian International Prize 2012 goes to Prof. Jaan EINASTO (Estonia) and Prof. Igor NOVIKOV (Russia) Viktor Ambartsumian International Prize has been established by the President of Armenia in 2009 and at present is one of the important awards in astronomy/astrophysics and related sciences. It is being awarded to outstanding scientists from any country and nationality having significant contribution in science. The Prize totals USD 500,000 and since 2010 is being awarded once every two years. March 18 was the deadline for nominations, and the International Steering Committee chaired by the President of the Armenian National Academy of Sciences Prof. Radik Martirosyan received nominations from national academies of sciences, universities, observatories, and Nobel Prize winners for 12 outstanding scientists and teams from different countries. After a thorough study of the nominated works, as well as independent referees’ reports, the Committee had several discussions and finally it was decided to share the Prize between Prof. Jaan Einasto (Tartu Observatory, Estonia), nominated by Tartu Observatory “for his fundamental contributions to the discovery of dark matter and the cosmic web” and Prof. Igor Novikov (Astro-Space Center, P.N. Lebedev Physics Institute, Russia) nominated by the Institute of Theoretical Physics and Astronomy of Vilnius University, Lithuania “for his pioneering formulation how to confirm observationally that our Universe started as a hot one, and for proposing the method for determination of quasar masses”. Jaan Einasto (83) is a senior scientist at the Tartu Observatory, Estonia. Since 1952 he works at Tartu Observatory. -
Messenger-No117.Pdf
ESO WELCOMES FINLANDINLAND AS ELEVENTH MEMBER STAATE CATHERINE CESARSKY, ESO DIRECTOR GENERAL n early July, Finland joined ESO as Education and Science, and exchanged which started in June 2002, and were con- the eleventh member state, following preliminary information. I was then invit- ducted satisfactorily through 2003, mak- II the completion of the formal acces- ed to Helsinki and, with Massimo ing possible a visit to Garching on 9 sion procedure. Before this event, howev- Tarenghi, we presented ESO and its scien- February 2004 by the Finnish Minister of er, Finland and ESO had been in contact tific and technological programmes and Education and Science, Ms. Tuula for a long time. Under an agreement with had a meeting with Finnish authorities, Haatainen, to sign the membership agree- Sweden, Finnish astronomers had for setting up the process towards formal ment together with myself. quite a while enjoyed access to the SEST membership. In March 2000, an interna- Before that, in early November 2003, at La Silla. Finland had also been a very tional evaluation panel, established by the ESO participated in the Helsinki Space active participant in ESO’s educational Academy of Finland, recommended Exhibition at the Kaapelitehdas Cultural activities since they began in 1993. It Finland to join ESO “anticipating further Centre with approx. 24,000 visitors. became clear, that science and technology, increase in the world-standing of ESO warmly welcomes the new mem- as well as education, were priority areas Astronomy in Finland”. In February 2002, ber country and its scientific community for the Finnish government. we were invited to hold an information that is renowned for its expertise in many Meanwhile, the optical astronomers in seminar on ESO in Helsinki as a prelude frontline areas. -
Sandra Faber Receives $500,000 Gruber Cosmology Prize
Media Contact: A. Sarah Hreha +1 (203) 432-6231 [email protected] Online Newsroom: www.gruber.yale.edu/news-media SANDRA FABER RECEIVES $500,000 GRUBER COSMOLOGY PRIZE FOR CAREER ACHIEVEMENTS Sandra Faber May 17, 2017, New Haven, CT – The 2017 Gruber Foundation Cosmology Prize recognizes Sandra M. Faber for a body of work that has helped establish many of the foundational principles underlying the modern understanding of the universe on the largest scales. The citation praises Faber for “her groundbreaking studies of the structure, dynamics, and evolution of galaxies.” That work has led to the widespread acceptance of the need to study dark matter, to an appreciation of the inextricable relationship between the presence of dark matter and the formation of galaxies, and to the recognition that black holes reside at the heart of most large galaxies. She has also made significant contributions to the innovations in telescope technology that have revolutionized modern astronomy. Through these myriad achievements, the Gruber citation adds, Faber has “aided and inspired the work of astronomers and cosmologists worldwide.” Faber will receive the $500,000 award as well as a gold medal at a ceremony this fall. Less than a hundred years ago, astronomers were still debating whether our Milky Way Galaxy was the entirety of the universe or if other galaxies existed beyond our own. Today astronomers estimate the number of galaxies within the visible universe at somewhere between 200 billion and 2 trillion. For more than four decades Faber—now Professor Emerita at the University of California, Santa Cruz, and Astronomer Emerita of the University of California Observatories—has served as a pivotal figure in leading and guiding the exploration of this unimaginably vast virgin scientific territory. -
Kinematic and Emission Analysis of the Relativistic Jet in the Blazar B1551+130 Using VLBI Data
Kinematic and Emission Analysis of the Relativistic Jet in the Blazar B1551+130 using VLBI Data Shaun Julian Nicol MSci Project Imperial College London Host Institute: Supervisor: Universitat de Val`encia Prof. Eduardo Ros Ibarra June 2012 Abstract Very Long Baseline Interferometry (VLBI) allows the most energetic structures in our universe to be observed with sub-milliarcsecond resolution (parsecs at cosmological distances). These methods are particularly effective in observing the relativistic jets extending from the black hole region of active galactic nu- clei (AGN). Six epochs of VLBI data from the MOJAVE 2 cm survey taken between June 2009 and April 2012 are used to carry out the kinematic analysis of the relativistic jet in the flat spectrum radio quasar B1551+130 with red- shift z = 1:308. The apparent velocities of areas of enhanced radio emission, or `knots', in the jet, calculated through the model fitting technique, are pre- sented along with images of the source obtained through the hybrid mapping process. Superluminal velocities for the `knots' are observed with the highest apparent velocity being 10.21.8c. From this maximum velocity, the viewing angle of 5.6◦ 1◦ is derived, agreeing with the classification of the source as a FSRQ. An estimate of the luminosity Doppler boosting factor gives a value of order 102. Two jet features are observed with negative superluminal velocities, the most significant being the region closest to the base or `core' of the jet ob- served with a velocity of {10.62.7c. The flux of this region undergoes a large increase during the most recent observations, between mid 2011 and mid 2012. -
Icranet Scientific Report 2009
Cosmology group of Tartu Observatory 1 The cosmology group of Tartu Observatory 1.1 Science staff members Jaan Einasto, Maret Einasto, Mirt Gramann, Urmas Haud, Gert Hutsi, Juhan Lauri Liivamägi, Valery Malyuto; Enn Saar, Ivan Suhhonenko, Erik Tago, Antti Tamm, Elmo Tempel, Peeter Tenjes, Jaan Vennik; 1.2 PhD student Tiit Sepp 1.3 Technicians Peeter Einasto, Triin Einasto, Margus Sisask. 1527 2 Scientific studies I will classify the results according to the project goals. 2.1 Testing the inflationary paradigm In order to test the inflationary paradigm (the initial extremely fast expansion of the Universe) we studied the observational traces of baryon oscillations (BAO), predicted by inflation theories. Gert Hütsi discovered the traces of BAO in the power spectrum of the galaxy distribution, using the catalogue of the distant galaxy clusters of the Sloan Digital Sky Survey (SDSS). The paper has been accepted by ’Monthly Notices of the Royal Astronomical Society’ (MNRAS). Enn Saar, together with Ivan Suhhonenko and colleagues from the Valen- cia and Tuorla observatories demonstrated that photometric redshifts can be used to restore the matter correlation functions of deep lightcones. The paper has been published by MNRAS. Gert Hütsi, together with colleagues from the Hiroshima University, stud- ied the damping of BAO, and estimated the structure growth rate. One paper has been published (Physical Review), another submitted. Traces of BAO can be sought also in the correlation function of galaxies. Enn Saar and Elmo Tempel, together with colleagues from Valencia, found these. Enn Saar also solved the problem of bootstrap estimation of correlation function errors. The paper was published in ’Astrophysical Journal Letters’. -
Lars Hernquist and Volker Springel Receive $500,000 Gruber Cosmology Prize
Media Contact: A. Sarah Hreha +1 (203) 432‐6231 [email protected] Online Newsroom: https://gruber.yale.edu/news‐media Lars Hernquist and Volker Springel Receive $500,000 Gruber Cosmology Prize Lars Hernquist Volker Springel New Haven, CT — The 2020 Gruber Cosmology Prize recognizes Lars Hernquist, Center for Astrophysics | Harvard & Smithsonian, and Volker Springel, Max Planck Institute for Astrophysics, for their defining contributions to cosmological simulations, a method that tests existing theories of, and inspires new investigations into, the formation of structures at every scale from stars to galaxies to the universe itself. Hernquist and Springel will divide the $500,000 award, and each will receive a gold laureate pin at a ceremony that will take place later this year. The award recognizes their transformative work on structure formation in the universe, and development of numerical algorithms and community codes further used by many other researchers to significantly advance the field. Hernquist was a pioneer in cosmological simulations when he joined the fledgling field in the late 1980s, and since then he has become one of its most influential figures. Springel, who entered the field in 1998 and first partnered with Hernquist in the early 2000s, has written and applied several of the most widely used codes in cosmological research. Together Hernquist and Springel constitute, in the words of one Gruber Prize nominator, “one of the most productive collaborations ever in cosmology.” Computational simulations in cosmology begin with the traditional source of astronomical data: observations of the universe. Then, through a combination of theory and known physics that might approximate initial conditions, the simulations recreate the subsequent processes that would have led to the current structure. -
Annual Report 2013 1 Research
Annual Report 2013 Jaan Einasto 1 Research I participated in the comparison of the structure of groups of galaxies of the Sloan Digital Sky Survey seventh data release (SDSS DR7) galaxy and galaxy group catalogues and groups found for the Millennium N-body simulation by Nurmi et al. (2013). We analysed the group luminosities, group richnesses, virial radii, sizes of groups and their rms velocities for four volume-limited samples from observations and simulations. Our results showed that the spatial densities of groups agree within one order of magnitude in all samples with a rather good agreement between the mock catalogues and observations. I participated in the search for shell-like structures in the distribution of nearby rich clusters of galaxies drawn from the SDSS DR8, initiated by Maret Einasto (Einasto et al., 2013b). We find the maxima in the distribution of distances from rich galaxy clusters to other groups and clusters at distance of about 120 h−1 Mpc suggesting a density enhancement at these distances from rich clusters, and possible indication of shell-like structures. The rich cluster A1795, the central cluster of the Bootes supercluster, has the highest maximum in the distance distribution of other groups and clusters around them at distance of about 120 h−1 Mpc among our rich cluster sample, and another maximum at a distance of about 240 h−1 Mpc. However, the radius of the possible shell is larger than expected for a BAO shell (≈ 109 h−1 Mpc). Together with Maret Einasto and collaborators I studied the morphology and galaxy content of SDSS DR8 superclusters (Einasto et al., 2013a). -
What Is Dark Matter
What is Dark Ma,er? History of what the universe is made of, through 2003 Zackary Scholl October 8th, 2009 Early astronomy methods • Measuring distances to galaxies – “Standard candle” Type Ia Supernova used to measure distance to galaxies (1-100 Mps) • Measuring velociQes of galaxies – Speed is proporQonal to amount of Doppler shiR in emission and absorpQon lines Early astronomy methods • EsQmaQng masses of galaxies – From mass to luminosity raQo (M/L) • Based on the sun (Sun’s M/L = 1) • Our galaxy has M/L is 6 – From rotaQonal velocity of gas clouds and stars • Kepler’s laws of moQon say that faster stellar moQons are caused by larger mass concentraQon First menQon of “dark ma,er” • In 1933 Fritz Zwicky analyzed velociQes of galaxies in Coma cluster • Calculated mass was 50 Qmes larger than mass esQmated from luminosity. “If this is confirmed we would arrive at the astonishing conclusion that dark maer is present with much greater density than luminous ma,er.” – Zwicky, 1933 More missing mass… • In 1936 Sinclair Smith concluded Virgo galaxy has 10 Qmes the mass esQmated from luminosity. • In 1940 Jan Oort concluded NGC 3115 has 25 Qmes mass esQmated from luminosity. “[T]he distribuQon of mass in this system appears to bear almost no relaQon to that of light.“ – Oort 1940 Be,er astronomy methods • In 1950’s astronomers started using radio telescopes • In 1960’s astronomers started using X-ray telescopes • Astronomers began invesQgaQng dynamics of galaxies • Evidence accumulated for idea of missing mass Evidence of “missing ma,er” • In -
HAS the UNIVERSE the CELL STRUCTURE? Mihkel Jôeveer and Jaan Einasto Tartu Astrophysical Observatory Tôravere 20244 Estonia, U
HAS THE UNIVERSE THE CELL STRUCTURE? Mihkel Jôeveer and Jaan Einasto Tartu Astrophysical Observatory Tôravere 20244 Estonia, U.S.S.R. 1. INTRODUCTION As demonstrated by de Vaucouleurs (1956, 1975a,b, 1976), Abell (1961), Karachentsev (1966), Kiang and Saslaw (1969) and others, clusters of galaxies as well as groups of galaxies have a tendency to form second-order clusters of galaxies, often called superclusters. Recent statistical studies by the Princeton group (Davis, Groth and Peebles 1977, Seldner and Peebles 1977a) have confirmed this result. Statistical studies, however, give little information about the internal structure of second-order clusters. To get a clearer picture of the distribution of galaxies in space, we have studied the three-dimensional distribution of galaxies and clusters1 of galaxies. We have used recession velocities of galaxies and mean velocities of clusters as distance indicators supposing, following Sandage and Tammann (1975) , that the expansion of the Universe is uniform. 2. OBSERVATIONAL DATA The distribution of the following objects has been studied: Abell clusters of galaxies (Abell 1958), Zwicky clusters of galaxies (Zwicky et al. 1961-68), groups and pairs of galaxies, and single galaxies. The second Reference Catalogue of Bright Galaxies (de Vaucouleurs, de Vaucouleurs and Corwin 1976) has served as the source of the radial velocities for galaxies. Radial velocities of the Abell clusters have been taken from a compilation by Corwin (1974) supplemented by some new determinations (Faber and Dressier 1976). Only nearby objects have been studied: Zwicky clusters belonging to the "near" distance class and galaxies having redshifts not in excess of 15 000 km s_1 have been used.