scholarly journals Clustering, Isotropy, and Redshift Cutoff

1986 ◽  
Vol 119 ◽  
pp. 447-454
Author(s):  
Patrick S. Osmer
Keyword(s):  
Optical Depth ◽  
Three Dimensional ◽  
Radial Distance ◽  
Specific Question ◽  
Dimensional Distribution ◽  
Steep Decline ◽  
Age Of The Universe ◽  
Short Time ◽  
The Universe ◽  
Luminosity Evolution

The topics of clustering, isotropy, and redshift cutoff are in reality just different aspects of the problem of the three-dimensional distribution of quasars, assuming, of course that the redshifts are cosmological and therefore an indication of radial distance. The distribution in redshift has additional interest because of the substantial lookback times involved, up to four fifths of the age of the universe. The radial variation of quasar density between redshift zero and two, and the attendant questions of density and luminosity evolution, are discussed elsewhere in this symposium by Green and shall not be treated here. Rather we shall concern ourselves with the behavior at redshifts larger than two and the specific question of a steep decline of quasar density at redshifts near three. For simplicity we may characterize the problem as one of studying either the formation of quasars as we normally see them in a cosmologically short time or of the properties of the universe and its optical depth, should intergalactic absorption contribute significantly to blocking our view at redshift three. Of course other hypotheses are also possible.

scholarly journals The flatness problem and the age of the Universe

2020 ◽  
Vol 495 (4) ◽  
pp. 3571-3575
Author(s):  
Phillip Helbig
Keyword(s):  
Early Universe ◽  
Time Scale ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Fine Tuning ◽  
Density Parameter ◽  
Age Of The Universe ◽  
Short Time ◽  
The Universe ◽  
Flatness Problem

ABSTRACT Several authors have made claims, none of which has been rebutted, that the flatness problem, as formulated by Dicke and Peebles, is not really a problem but rather a misunderstanding. Nevertheless, the flatness problem is still widely perceived to be real. Most of the arguments against the idea of a flatness problem are based on the change with time of the density parameter Ω and normalized cosmological constant λ and, since the Hubble constant H is not considered, are independent of time-scale. An independent claim is that fine-tuning is required in order to produce a Universe which neither collapsed after a short time nor expanded so quickly that no structure formation could take place. I show that this claim does not imply that fine-tuning of the basic cosmological parameters is necessary, in part for similar reasons as in the more restricted flatness problem and in part due to an incorrect application of the idea of perturbing the early Universe in a gedankenexperiment; I discuss some typical pitfalls of the latter.

Statistical studies of the spatial distribution of galaxies

1996 ◽  
Vol 28 (02) ◽  
pp. 337-338
Author(s):  
Vicent J. Martínez ◽  
María Jesús Pons-Bordería
Keyword(s):  
Spatial Distribution ◽  
Structure Formation ◽  
Statistical Study ◽  
Three Dimensional ◽  
Dimensional Distribution ◽  
Statistical Studies ◽  
The Universe ◽  
Clustering Patterns

The statistical study of the clustering patterns formed by the three-dimensional distribution of galaxies is one of the most important observational clues to discriminate between rival theories of structure formation in the Universe.

scholarly journals On the Use of Fractal Concepts in Analysis of Distributions of Galaxies

1996 ◽  
Vol 168 ◽  
pp. 473-475
Author(s):  
I.B. Vavilova
Keyword(s):  
Fractal Structure ◽  
Three Dimensional ◽  
Fractal Pattern ◽  
Galaxy Distribution ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Good Review ◽  
Dimensional Distribution ◽  
The Universe ◽  
Scaling Index

The well- grounded polemics about the fractal structure of the Universe and a new cosmological picture which appears in connection with this, in first instance the absence of any evidence for homogenization up to present observational limits 200h−1Mpc, have been detailed at the work by Coleman, Pietronero (1992). Two versions on nature of fractal pattern of the galaxy distribution in the observed universe also are now: it behaves like a simple homogeneous fractal (Pietronero 1987; Coleman et al. 1988) and as a multifractal - fractal having more than one scaling index (Jones et al. 1988; Martinez, Jones 1990; Martinez et al. 1990; Borgani et al. 1993 (with the good review for matter of above)).This work does not play decisively into hands of these versions so the fractal concepts, exactly a selfsimilarity and multifractal, were applied here for the analysis oftwo - dimensionaldistribution of thebrightgalaxies and dwarf galaxies of the low surface brightness (LSBD) belonging to the Local Supercluster (LS). But if the observed universe holds the fractal structure, so it is useful to trace over the lower fractal pattern on the small scales of clustering of galaxies within the framework of the known superclusters and, in the first instance, within the local overdensity of galaxies. This work is a preliminary before preparing one with the same analysis of three- dimensional distribution of galaxies of LS.

scholarly journals The intergalactic medium in the cosmic web

2014 ◽  
Vol 11 (S308) ◽  
pp. 364-367
Author(s):  
Nicolas Tejos
Keyword(s):  
Intergalactic Medium ◽  
Three Dimensional ◽  
Baryonic Matter ◽  
One Dimensional ◽  
Star Forming ◽  
Galaxy Surveys ◽  
Dimensional Distribution ◽  
Formation And Evolution ◽  
The Universe ◽  
Cross Matching

AbstractThe intergalactic medium (IGM) accounts for ≳ 90% of baryons at all epochs and yet its three dimensional distribution in the cosmic web remains mostly unknown. This is so because the only feasible way to observe the bulk of the IGM is through intervening absorption line systems in the spectra of bright background sources, which limits its characterization to being one-dimensional. Still, an averaged three dimensional picture can be obtained by combining and cross-matching multiple one-dimensional IGM information with three-dimensional galaxy surveys. Here, we present our recent and current efforts to map and characterize the IGM in the cosmic web using galaxies as tracers of the underlying mass distribution. In particular, we summarize our results on: (i) IGM around star-forming and non-star-forming galaxies; (ii) IGM within and around galaxy voids; and (iii) IGM in intercluster filaments. With these datasets, we can directly test the modern paradigm of structure formation and evolution of baryonic matter in the Universe.

scholarly journals Determining Ω0 and λ0 from Cosmological Redshift Distortion of Galaxies and Quasars

1999 ◽  
Vol 183 ◽  
pp. 235-240
Author(s):  
Yasushi Suto
Keyword(s):  
Large Scale ◽  
Collaborative Work ◽  
Cosmological Parameters ◽  
Three Dimensional ◽  
Density Parameter ◽  
Cosmological Redshift ◽  
Peculiar Velocity ◽  
Dimensional Distribution ◽  
Space Distortion ◽  
The Universe

The three-dimensional distribution of galaxies in the redshift surveys differ from the true one since the distance to each galaxy cannot be determined by its redshift z only; for z ≪ 1 the peculiar velocity of galaxies, typically ∼ (100–1000)km/sec, contaminates the true recession velocity of the Hubble flow, while the true distance for objects at z ≳ 1 sensitively depends on the (unknown and thus assumed) cosmological parameters. This hampers the effort to understand the true distribution of large-scale structure of the universe. Nevertheless such redshift-space distortion effects are quite useful since through the detailed theoretical modeling, one can derive the peculiar velocity dispersions of galaxies as a function of separation, and also can infer the cosmological density parameter Ω0, the dimensionless cosmological constant λ0, and the spatial biasing factor b of galaxies and/or quasars, for instance. In this talk, I discuss the importance of such redshift distortion induced by the geometry of the universe, which summarizes the recent results of my collaborative work in this topic (Matsubara & Suto 1996; Nakamura, Matsubara, & Suto 1998; Magira, Matsubara, Jing, & Suto 1998).

scholarly journals Mid-IR cosmological spectrophotometric surveys from space: Measuring AGN and star formation at the cosmic noon with a SPICA-like mission

2021 ◽  
Vol 38 ◽  
Author(s):  
Luigi Spinoglio ◽  
Sabrina Mordini ◽  
Juan Antonio Fernández-Ontiveros ◽  
Almudena Alonso-Herrero ◽  
Lee Armus ◽  
...  
Keyword(s):  
Fine Structure ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Formation Rate ◽  
Three Dimensional ◽  
Cosmic Time ◽  
Ir Camera ◽  
Infrared Telescope ◽  
Age Of The Universe ◽  
The Universe

Abstract We use the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) project as a template to demonstrate how deep spectrophotometric surveys covering large cosmological volumes over extended fields (1– $15\, \rm{deg^2}$ ) with a mid-IR imaging spectrometer (17– $36\, \rm{\rm{\upmu m}}$ ) in conjunction with deep $70\, \rm{\rm{\upmu m}}$ photometry with a far-IR camera, at wavelengths which are not affected by dust extinction can answer the most crucial questions in current galaxy evolution studies. A SPICA-like mission will be able for the first time to provide an unobscured three-dimensional (3D, i.e. x, y, and redshift z) view of galaxy evolution back to an age of the universe of less than $\sim$ 2 Gyrs, in the mid-IR rest frame. This survey strategy will produce a full census of the Star Formation Rate (SFR) in the universe, using polycyclic aromatic hydrocarbons (PAH) bands and fine-structure ionic lines, reaching the characteristic knee of the galaxy luminosity function, where the bulk of the population is distributed, at any redshift up to $z \sim 3.5$ . Deep follow-up pointed spectroscopic observations with grating spectrometers onboard the satellite, across the full IR spectral range (17– $210\, \rm{\rm{\upmu m}}$ ), would simultaneously measure Black Hole Accretion Rate (BHAR), from high-ionisation fine-structure lines, and SFR, from PAH and low- to mid-ionisation lines in thousands of galaxies from solar to low metallicities, down to the knee of their luminosity functions. The analysis of the resulting atlas of IR spectra will reveal the physical processes at play in evolving galaxies across cosmic time, especially its heavily dust-embedded phase during the activity peak at the cosmic noon ( $z \sim 1$ –3), through IR emission lines and features that are insensitive to the dust obscuration.

Statistical studies of the spatial distribution of galaxies

1996 ◽  
Vol 28 (2) ◽  
pp. 337-338
Author(s):  
Vicent J. Martínez ◽  
María Jesús Pons-Bordería
Keyword(s):  
Spatial Distribution ◽  
Structure Formation ◽  
Statistical Study ◽  
Three Dimensional ◽  
Dimensional Distribution ◽  
Statistical Studies ◽  
The Universe ◽  
Clustering Patterns

The statistical study of the clustering patterns formed by the three-dimensional distribution of galaxies is one of the most important observational clues to discriminate between rival theories of structure formation in the Universe.

Three-dimensional distribution of ribulose-1, 5-bisphosphate carboxylase/oxygemase during the early development of proplastids in dark-grown Euglena cells transferred to an inorganic medium

1990 ◽  
Vol 48 (3) ◽  
pp. 906-907
Author(s):  
Tomoko Ehara ◽  
Shuji Sumida ◽  
Tetsuaki Osafune ◽  
Eiji Hase
Keyword(s):  
Cell Suspension ◽  
Euglena Gracilis ◽  
Carbon Materials ◽  
Three Dimensional ◽  
Peripheral Region ◽  
Plastid Development ◽  
Bisphosphate Carboxylase ◽  
Inorganic Medium ◽  
Ribulose 1 ◽  
Dimensional Distribution

As shown previously, Euglena cells grown in Hutner’s medium in the dark without agitation accumulate wax as well as paramylum, and contain proplastids showing no internal structure except for a single prothylakoid existing close to the envelope. When the cells are transferred to an inorganic medium containing ammonium salt and the cell suspension is aerated in the dark, the wax was oxidatively metabolized, providing carbon materials and energy 23 for some dark processes of plastid development. Under these conditions, pyrenoid-like structures (called “pro-pyrenoids”) are formed at the sites adjacent to the prolamel larbodies (PLB) localized in the peripheral region of the proplastid. The single prothylakoid becomes paired with a newly formed prothylakoid, and a part of the paired prothylakoids is extended, with foldings, in to the “propyrenoid”. In this study, we observed a concentration of RuBisCO in the “propyrenoid” of Euglena gracilis strain Z using immunoelectron microscopy.

A New Way to Estimate the Age of the Universe

2014 ◽  
Vol 8 (6) ◽  
pp. 186
Author(s):  
Alilou Khalid ◽  
Az-Eddine L. Marrakchi
Keyword(s):  
Age Of The Universe ◽  
The Universe

PERCEPTION AND INTERPRETATION OF CREATIVITY OF ALISHER NAVOI IN FRENCH ORIENTAL STUDIES

2020 ◽  
Vol 6 (3) ◽  
pp. 40-50
Author(s):  
Mukhammadjon Holbekov ◽  
Keyword(s):  
The World ◽  
Oriental Studies ◽  
Short Time ◽  
The Universe ◽  
Precious Stones

The great Uzbek poet Alisher Navoi(1441-1501), during his lifetime, was widely known not only in his homeland, but also far beyond its borders. A contemporary and biographer of Navoi, the famous historian Hondemir, of course, not without some hyperbole, wrote: "He (Navoi -M.Kh.) in a short time took the cane of primacy from his peers; the fame of his talents spread to all ends of the world, and the stories of the firmness of his noble mind from mouth to mouth were innumerable.The pearls of his poetry adorned the leaves of the Book of Fates, the precious stones of his poetry filled the shells of the universe with pearls of beauty

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