scholarly journals Absorption Line Surveys at Intermediate Redshift

2011 ◽  
Vol 7 (S280) ◽  
pp. 339-350 ◽  
Author(s):  
Sébastien Muller
Keyword(s):  
Fundamental Constants ◽  
Molecular Absorption ◽  
Chemical Enrichment ◽  
Distant Galaxies ◽  
Absorption Studies ◽  
History Of ◽  
Spectral Survey ◽  
Intermediate Redshift ◽  
The Universe ◽  
Compact Array

AbstractThe z=0.89 spiral galaxy located on the line of sight to the quasar PKS1830-211 is right now the extragalactic object with the largest number of detected molecular species (34, plus isotopic variants). This remarkable molecular inventory was recently built after an unbiased spectral survey of molecular absorption lines with the Australia Telescope Compact Array in the 7 mm band. We present the results of this survey, as a showcase of the various interests of molecular absorption studies at intermediate redshift: chemical inventory and gas properties in distant galaxies, chemical enrichment history of the Universe, measurements of the CMB temperature as a function of z, and constraints on the constancy of fundamental constants.

scholarly journals Thousands of Milky Ways: galaxy satellites and building blocks

2009 ◽  
Vol 5 (S262) ◽  
pp. 240-243
Author(s):  
Nelson Padilla ◽  
Claudia Lagos ◽  
Sofía Cora
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Galactic Nuclei ◽  
Building Blocks ◽  
Chemical Enrichment ◽  
Stellar Formation ◽  
History Of ◽  
The Universe

AbstractA semi-analytic model of galaxy formation with and without active galactic nuclei feedback is used to study the nature of possible building blocks (BBs) of z = 0 galaxies, including those of Milky-Way types. We find that BBs can show an important range of properties arising from environmental variables such as host halo mass, and whether a galaxy is a satellite within its host halo; the stellar formation histories are comparatively faster and the chemical enrichment is more efficient in BBs than in surviving satellites, in accordance with recent metallicity measurements for the Milky Way. These results can be used in combination with observational constraints to continue probing the ability of the cold dark-matter scenario to reproduce the history of galaxy demography in the Universe.

scholarly journals The First Stars: clues from quasar absorption systems

2011 ◽  
Vol 467 (2134) ◽  
pp. 2735-2751 ◽  
Author(s):  
Max Pettini
Keyword(s):  
Big Bang ◽  
First Stars ◽  
Rich Diversity ◽  
Distant Galaxies ◽  
Look Back ◽  
Recent Developments ◽  
History Of ◽  
The Rich ◽  
The Big Bang ◽  
The Universe

Astronomers now have at their disposal telescopes and instruments that allow them to look back in time over most of the history of the Universe, from the present epoch to less than a billion years after the Big Bang, when the Universe was still in its infancy. Using quasars (the bright nuclei of distant galaxies) as background sources of light, we can follow the evolution of galaxies and of the matter between them from the First Stars to the rich diversity of the Universe today. In this article, I focus on recent developments in the study of the most metal-poor gas seen in the spectra of quasars, whose properties can be used to infer the nature of the First Stars and, in some cases, even determine the universal fraction of baryons.

scholarly journals Quasars as tracers of cosmic flows

2014 ◽  
Vol 11 (S308) ◽  
pp. 344-345
Author(s):  
J. Modzelewska ◽  
B. Czerny ◽  
M. Bilicki ◽  
K. Hryniewicz ◽  
M. Krupa ◽  
...  
Keyword(s):  
Time Delay ◽  
South African ◽  
Line Intensity ◽  
Line Shape ◽  
History Of ◽  
Photometric Monitoring ◽  
Intermediate Redshift ◽  
The Universe ◽  
Shape Changes ◽  
The Continuum

AbstractQuasars, as the most luminous persistent sources in the Universe, have broad applications for cosmological studies. In particular, they can be employed to directly measure the expansion history of the Universe, similarly to SNe Ia. The advantage of quasars is that they are numerous, cover a broad range of redshifts, up to z = 7, and do not show significant evolution of metallicity with redshift. The idea is based on the relation between the time delay of an emission line and the continuum, and the absolute monochromatic luminosity of a quasar. For intermediate redshift quasars, the suitable line is Mg II. Between December 2012 and March 2014, we performed five spectroscopic observations of the QSO CTS C30.10 (z = 0.900) using the South African Large Telesope (SALT), supplemented with photometric monitoring, with the aim of determining the variability of the line shape, changes in the total line intensity and in the continuum. We show that the method is very promising.

Roshdi Rashed

2018 ◽  
Vol 11 (1-2) ◽  
pp. 279-295
Author(s):  
Mohammed Aref
Keyword(s):  
Review Essay ◽  
Great Book ◽  
Mathematical Language ◽  
Single Word ◽  
Major Work ◽  
Galileo Galilei ◽  
Elementary Knowledge ◽  
History Of ◽  
The Universe

This review essay introduces the work of the Egyptian scientific historian and philosopher Roshdi Rashed, a pioneer in the field of the history of Arab sciences. The article is based on the five volumes he originally wrote in French and later translated into Arabic, which were published by the Centre for Arab Unity Studies and which are now widely acclaimed as a unique effort to unveil the achievements of Arab scientists. The essay reviews this major work, which seems, like Plato’s Republic to have “No Entry for Those Who Have No Knowledge of Mathematics” written on its gate. If you force your way in, even with elementary knowledge of computation, a philosophy will unfold before your eyes, described by the Italian astronomer Galileo Galilei as “written in that great book which ever lies before our eyes—I mean the universe—but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. This book is written in the mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth.” The essay is a journey through this labyrinth where the history of world mathematics got lost and was chronicled by Rashed in five volumes translated from the French into Arabic. It took him fifteen years to complete.

Turning Aliens into Socialists

2010 ◽  
Vol 1 (1) ◽  
pp. 75-93
Author(s):  
Jessica Moberg
Keyword(s):  
Outer Space ◽  
The United States ◽  
Second World War ◽  
World War ◽  
History Of ◽  
Swedish History ◽  
Second World ◽  
The Universe ◽  
Highly Evolved

Immediately after the Second World War Sweden was struck by a wave of sightings of strange flying objects. In some cases these mass sightings resulted in panic, particularly after authorities failed to identify them. Decades later, these phenomena were interpreted by two members of the Swedish UFO movement, Erland Sandqvist and Gösta Rehn, as alien spaceships, or UFOs. Rehn argued that ‘[t]here is nothing so dramatic in the Swedish history of UFOs as this invasion of alien fly-things’ (Rehn 1969: 50). In this article the interpretation of such sightings proposed by these authors, namely that we are visited by extraterrestrials from outer space, is approached from the perspective of myth theory. According to this mythical theme, not only are we are not alone in the universe, but also the history of humankind has been shaped by encounters with more highly-evolved alien beings. In their modern day form, these kinds of ideas about aliens and UFOs originated in the United States. The reasoning of Sandqvist and Rehn exemplifies the localization process that took place as members of the Swedish UFO movement began to produce their own narratives about aliens and UFOs. The question I will address is: in what ways do these stories change in new contexts? Texts produced by the Swedish UFO movement are analyzed as a case study of this process.

Galileo Unbound

2018 ◽  
Author(s):  
David D. Nolte
Keyword(s):  
Free Fall ◽  
The Sun ◽  
Quantum Field ◽  
Many Worlds ◽  
Quantum Particles ◽  
Light Rays ◽  
History Of ◽  
And Control ◽  
The Universe ◽  
Insight Into

Galileo Unbound: A Path Across Life, The Universe and Everything traces the journey that brought us from Galileo’s law of free fall to today’s geneticists measuring evolutionary drift, entangled quantum particles moving among many worlds, and our lives as trajectories traversing a health space with thousands of dimensions. Remarkably, common themes persist that predict the evolution of species as readily as the orbits of planets or the collapse of stars into black holes. This book tells the history of spaces of expanding dimension and increasing abstraction and how they continue today to give new insight into the physics of complex systems. Galileo published the first modern law of motion, the Law of Fall, that was ideal and simple, laying the foundation upon which Newton built the first theory of dynamics. Early in the twentieth century, geometry became the cause of motion rather than the result when Einstein envisioned the fabric of space-time warped by mass and energy, forcing light rays to bend past the Sun. Possibly more radical was Feynman’s dilemma of quantum particles taking all paths at once—setting the stage for the modern fields of quantum field theory and quantum computing. Yet as concepts of motion have evolved, one thing has remained constant, the need to track ever more complex changes and to capture their essence, to find patterns in the chaos as we try to predict and control our world.

scholarly journals Recent Near-Infrared Light-Activated Nanomedicine toward Precision Cancer Therapy

2021 ◽  
Author(s):  
Xiaowei Luan ◽  
Yongchun Pan ◽  
Yanfeng Gao ◽  
Yujun Song
Keyword(s):  
Cancer Therapy ◽  
Near Infrared ◽  
Infrared Light ◽  
Human Society ◽  
Near Infrared Light ◽  
History Of ◽  
The Universe

Light has witnessed the history of mankind and even the universe. It is of great significances to the life of human society, contributing to energy, agriculture, communication, and much more....

scholarly journals Dust Production around Carbon-Rich Stars: The Role of Metallicity

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 233
Author(s):  
Ambra Nanni ◽  
Sergio Cristallo ◽  
Jacco Th. van Loon ◽  
Martin A. T. Groenewegen
Keyword(s):  
Wind Speed ◽  
Galactic Halo ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Chemical Enrichment ◽  
Wide Range ◽  
The Universe

Background: Most of the stars in the Universe will end their evolution by losing their envelope during the thermally pulsing asymptotic giant branch (TP-AGB) phase, enriching the interstellar medium of galaxies with heavy elements, partially condensed into dust grains formed in their extended circumstellar envelopes. Among these stars, carbon-rich TP-AGB stars (C-stars) are particularly relevant for the chemical enrichment of galaxies. We here investigated the role of the metallicity in the dust formation process from a theoretical viewpoint. Methods: We coupled an up-to-date description of dust growth and dust-driven wind, which included the time-averaged effect of shocks, with FRUITY stellar evolutionary tracks. We compared our predictions with observations of C-stars in our Galaxy, in the Magellanic Clouds (LMC and SMC) and in the Galactic Halo, characterised by metallicity between solar and 1/10 of solar. Results: Our models explained the variation of the gas and dust content around C-stars derived from the IRS Spitzer spectra. The wind speed of the C-stars at varying metallicity was well reproduced by our description. We predicted the wind speed at metallicity down to 1/10 of solar in a wide range of mass-loss rates.

scholarly journals Displaced new physics at colliders and the early universe before its first second

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Francesco D’Eramo ◽  
Sam Junius ◽  
Laura Lopez-Honorez ◽  
Alberto Mariotti
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Upper Bound ◽  
New Physics ◽  
Early History ◽  
Relic Density ◽  
History Of ◽  
Indirect Information ◽  
The Universe

Abstract Displaced vertices at colliders, arising from the production and decay of long-lived particles, probe dark matter candidates produced via freeze-in. If one assumes a standard cosmological history, these decays happen inside the detector only if the dark matter is very light because of the relic density constraint. Here, we argue how displaced events could very well point to freeze-in within a non-standard early universe history. Focusing on the cosmology of inflationary reheating, we explore the interplay between the reheating temperature and collider signatures for minimal freeze-in scenarios. Observing displaced events at the LHC would allow to set an upper bound on the reheating temperature and, in general, to gather indirect information on the early history of the universe.

scholarly journals Connecting the Interstellar Gas and Dust Properties in Distant Galaxies Using Quasar Absorption Systems

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Monique C. Aller ◽  
Varsha P. Kulkarni ◽  
Donald G. York ◽  
Daniel E. Welty ◽  
Giovanni Vladilo ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Absorption Feature ◽  
Dust Grains ◽  
Interstellar Gas ◽  
Chemical Enrichment ◽  
Normal Galaxies ◽  
History Of ◽  
Dust Grain ◽  
Grain Properties

AbstractGas and dust grains are fundamental components of the interstellar medium and significantly impact many of the physical processes driving galaxy evolution, such as star-formation, and the heating, cooling, and ionization of the interstellar material. Quasar absorption systems (QASs), which trace intervening galaxies along the sightlines to luminous quasars, provide a valuable tool to directly study the properties of the interstellar gas and dust in distant, normal galaxies. We have established the presence of silicate dust grains in at least some gas-rich QASs, and find that they exist at higher optical depths than expected for diffuse gas in the Milky Way. Differences in the absorption feature shapes additionally suggest variations in the silicate dust grain properties, such as in the level of grain crystallinity, from system-to-system. We present results from a study of the gas and dust properties of QASs with adequate archival IR data to probe the silicate dust grain properties. We discuss our measurements of the strengths of the 10 and 18 μm silicate dust absorption features in the QASs, and constraints on the grain properties (e.g., composition, shape, crystallinity) based on fitted silicate profile templates. We investigate correlations between silicate dust abundance, reddening, and gas metallicity, which will yield valuable insights into the history of star formation and chemical enrichment in galaxies.

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