scholarly journals The Global Hubble Constant

1990 ◽  
Vol 43 (2) ◽  
pp. 189
Author(s):  
N Visvanathan
Keyword(s):  
Large Scale ◽  
Velocity Dispersion ◽  
Hubble Constant ◽  
Virgo Cluster ◽  
A Value ◽  
Best Value ◽  
Nearby Galaxies ◽  
Distance Data ◽  
Distance Relation

A review of large-scale investigations of the determination of H is presented. The infrared period-luminosity relation of Cepheids gives distances accurate to -2% to nearby galaxies. Based on the distances of M31, MH, N300 and N2403, a DM of 31 �30 �O� 20 has been derived to the nearby Virgo cluster from the TF relation of spirals at four wavebands. Distances to more distant clusters extending up to a redshift of -10000 km S-I obtained through the CM relation of E galaxies, the TF relation of spirals and the velocity dispersion-luminosity relation of E galaxies give a value of H of 71 km S-I Mpcl when these distances are normalised to a Virgo DM of 31�30. The scatter in the redshift-distance relation of these clusters is -500 km s-I arising from the presence of unaccounted peculiar motions of individual clusters. The magnitude limited all-sky samples of galaxies also give a value of H near 70 km S-I Mpcl once the data are corrected for Malmquist bias. The best value of the global Hubble constant obtained from the redshift-distance data of Virgo and farther clusters, as well as the magnitude limited samples involving various methods of determining distances by different observers, is 73 km S-i Mpcl . Taking into account the error in the calibration of our DM of Virgo we can set a generous error of 10 to this value of H.

A New Estlmate of the Hubble Constant Using the Virgo Cluster Distance

1985 ◽  
Vol 6 (2) ◽  
pp. 140-144
Author(s):  
N. Visvanathan
Keyword(s):  
Hubble Constant ◽  
Virgo Cluster ◽  
Distance Modulus ◽  
A Value ◽  
Cluster Distance ◽  
Nearby Galaxies

AbstractA new distance modulus (31.23) to the Virgo cluster is derived using the distances to nearby galaxies given by Sandage and Tammann, de Vaucouleurs, ourselves and DDO observers. This when combined with the undisturbed mean Virgo cluster velocity 1182 km s-1, gives a value for the global Hubble constant as 67 ±4 km s-1Mpc-1.

scholarly journals The Distribution of Bright Galaxies

1987 ◽  
Vol 124 ◽  
pp. 275-300
Author(s):  
G. Chincarini ◽  
G. Vettolani
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Velocity Dispersion ◽  
Virgo Cluster ◽  
Clusters Of Galaxies ◽  
Physical Mechanisms ◽  
Large Structures ◽  
Topology Of The Universe ◽  
Relevant Work

Following a brief review of the early developments in the field, we discuss a few new advances in the distribution of bright galaxies which occured after the extensive review paper by Oort (1983) We show that the large scale structure, shells, filaments and/or sheets, may bias the determination of the velocity dispersion in clusters of galaxies and that the boundaries of the voids may often be biassed by the clusters and groups velocity dispersion.Of interest are the very large structures selected on catalogs of clusters of galaxies. The “Local Structure” claimed by Tully seems to be somewhat flattened and about parallel to the plane of the Local Supercluster. If the structure is real the alignement is relevant in relation to the physical mechanisms at work at the time of formation. Noticeable progress has been done in the measurement of the large scale velocity field. Large scale motions may somewhat bias the study of the topology of the Universe.Relevant work has be done on the shape of the boundaries of the voids and observational work is progressing to detect faint galaxies in voids and determine their charactestics. This is important also in relation to the theory of biassed galaxy formation. To better focus the observational problem and eventually related biasses, we give some statistics on dwarf galaxies in the Virgo cluster.

scholarly journals Redshifts and Large Scale Structures

1983 ◽  
Vol 104 ◽  
pp. 159-165
Author(s):  
G. Chincarini
Keyword(s):  
Deceleration Parameter ◽  
Large Scale ◽  
Hubble Constant ◽  
Large Scale Structures ◽  
Classical Paper ◽  
Scale Structures

The effort to measure the geometry of space by experiment, that is, the determination of the Hubble Constant, Ho, and of the deceleration parameter, qo, led toward the end of the first half of the century, to the classical paper by Humason, Mayall, and Sandage (1956). Their catalogue contains 920 redshifts collected over a twenty-year period (1935–1955). Further redshifts of galaxies were measured to refine such determinations and to study the dynamics of clusters (Zwicky 1933).

scholarly journals Local Large-Scale Structure and the Assumption of Homogeneity

2014 ◽  
Vol 11 (S308) ◽  
pp. 295-298 ◽  
Author(s):  
Ryan C. Keenan ◽  
Amy J. Barger ◽  
Lennox L. Cowie
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Near Infrared ◽  
Mass Density ◽  
Hubble Constant ◽  
A Value ◽  
Accelerating Expansion ◽  
Luminous Matter ◽  
Local Measurements ◽  
The Universe

AbstractOur recent estimates of galaxy counts and the luminosity density in the near-infrared (Keenan et al. 2010, 2012) indicated that the local universe may be under-dense on radial scales of several hundred megaparsecs. Such a large-scale local under-density could introduce significant biases in the measurement and interpretation of cosmological observables, such as the inferred effects of dark energy on the rate of expansion. In Keenan et al. (2013), we measured the K-band luminosity density as a function of distance from us to test for such a local under-density. We made this measurement over the redshift range 0.01 < z < 0.2 (radial distances D ~ 50 - 800 h70−1 Mpc). We found that the shape of the K-band luminosity function is relatively constant as a function of distance and environment. We derive a local (z < 0.07, D < 300 h70−1 Mpc) K-band luminosity density that agrees well with previously published studies. At z > 0.07, we measure an increasing luminosity density that by z ~ 0.1 rises to a value of ~ 1.5 times higher than that measured locally. This implies that the stellar mass density follows a similar trend. Assuming that the underlying dark matter distribution is traced by this luminous matter, this suggests that the local mass density may be lower than the global mass density of the universe at an amplitude and on a scale that is sufficient to introduce significant biases into the measurement of basic cosmological observables. At least one study has shown that an under-density of roughly this amplitude and scale could resolve the apparent tension between direct local measurements of the Hubble constant and those inferred by Planck team. Other theoretical studies have concluded that such an under-density could account for what looks like an accelerating expansion, even when no dark energy is present.

scholarly journals Angular momentum-related probe of cold gas deficiencies

2020 ◽  
Vol 493 (4) ◽  
pp. 5024-5037
Author(s):  
Jie Li ◽  
Danail Obreschkow ◽  
Claudia Lagos ◽  
Luca Cortese ◽  
Charlotte Welker ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Velocity Dispersion ◽  
Virgo Cluster ◽  
Atomic Fraction ◽  
Cluster Galaxies ◽  
Nearby Galaxies ◽  
The Stability ◽  
Baryonic Mass ◽  
Log Ratio ◽  
Disc Galaxies

ABSTRACT Recent studies of neutral atomic hydrogen (H i) in nearby galaxies found that all field disc galaxies are H i saturated, in that they carry roughly as much H i as permitted before this gas becomes gravitationally unstable. By taking this H i saturation for granted, the atomic gas fraction fatm of galactic discs can be predicted as a function of the stability parameter q = jσ/(GM), where M and j are the baryonic mass and specific angular momentum of the disc and σ is the H i velocity dispersion (Obreschkow et al. 2016). The log-ratio Δfq between this predictor and the observed atomic fraction can be seen as a physically motivated ‘H i deficiency’. While field disc galaxies have Δfq ≈ 0, objects subject to environmental removal of H i are expected to have Δfq &gt; 0. Within this framework, we revisit the H i deficiencies of satellite galaxies in the Virgo cluster and in clusters of the EAGLE simulation. We find that observed and simulated cluster galaxies are H i deficient and that Δfq slightly increases when getting closer to the cluster centres. The Δfq values are similar to traditional H i deficiency estimators, but Δfq is more directly comparable between observations and simulations than morphology-based–deficiency estimators. By tracking the simulated H i deficient cluster galaxies back in time, we confirm that Δfq ≈ 0 until the galaxies first enter a halo with $M_{\rm halo}\gt 10^{13}\rm M_{\odot }$, at which moment they quickly lose H i by environmental effects. Finally, we use the simulation to investigate the links between Δfq and quenching of star formation.

scholarly journals 47. Cosmology

1976 ◽  
Vol 16 (3) ◽  
pp. 137-157
Author(s):  
M. S. Longair
Keyword(s):  
Deceleration Parameter ◽  
Hubble Constant ◽  
Density Parameter ◽  
Massive Galaxies ◽  
A Value ◽  
The Mean ◽  
Points Of View ◽  
The Universe

A major procedural advance in the determination of the H0 and Ω has been that the problem is now being attacked from many different points of view and to some extent the observations are converging on preferred values of H0 and Ω (Ω = density parameter = 8πGρ0/3H0 where ρ0 is the mean density of matter in the Universe and H0 is the Hubble constant; Ω = 2q0 where q0 is the deceleration parameter). The classical approaches through the redshift-magnitude relation for the most massive galaxies in clusters suggest a value of H0 = 60 km s-1 Mpc (see the review by Tammann in IAU Symp. 63).

scholarly journals Cepheid and Long – Period Variables in Virgo Cluster Galaxies

1993 ◽  
Vol 139 ◽  
pp. 81-89
Author(s):  
M.J. Pierce ◽  
R.D. McClure ◽  
D.L. Welch ◽  
R. Racine ◽  
S. van den Bergh
Keyword(s):  
High Resolution ◽  
Hubble Constant ◽  
Variable Stars ◽  
Virgo Cluster ◽  
Distance Scale ◽  
Cluster Galaxies ◽  
Cluster Distance ◽  
Resolution Imaging ◽  
Extragalactic Distance Scale

AbstractWe are currently undertaking a ground-based imaging survey which attempts to discover and determine periods for variable stars in Virgo Cluster galaxies. Such a survey is now feasible thanks to the high resolution imaging (FWHM ≤ 0.50 arcsec) routinely obtained with the High Resolution Camera on the Canada-France-Hawaii Telescope. The Virgo Cluster has long been considered a crucial “stepping-stone” in the extragalactic distance scale problem given that the cluster is at a “cosmologically interesting” distance and that there is little controversy in the relative distance between Virgo and more distant clusters, such as Coma. Consequently, much of the controversy regarding the extragalactic distance scale and the Hubble Constant can be eliminated with a determination of the Virgo Cluster distance. Some preliminary results and the prospects for establishing the distance to the Virgo Cluster using Cepheids and LPVs are discussed.

scholarly journals ANALYSIS OF PROFIT SHARING SYSTEM BEEF CATTLE BREEDING BUSINESS IN KLAMBIR V KEBUN HAMPARAN PERAK SUBDISTRICT DELI SERDANG DISTRICT

2017 ◽  
Vol 5 (2) ◽  
Author(s):  
Wilda Rifki ◽  
Y L Henuk ◽  
A H Daulay ◽  
Yunilas ◽  
N D Hanafi
Keyword(s):  
Beef Cattle ◽  
Household Income ◽  
Large Scale ◽  
Secondary Data ◽  
Profit Sharing ◽  
Primary Data ◽  
Small Scale ◽  
Cattle Breeding ◽  
A Value

The purpose of this research was to know the management of profit sharing system in the area, to analyze the income and profit of the investor and the farmer and the percentage of the contribution of the livestock business in fulfilling the income of the farmer family. This research was conducted in Klambir V Kebun Hamparan Perak Subdistrict Deli Serdang District for 2 month from July 2017 until August 2017. This research used primary data and secondary data. The location of the research and the determination of the respondents was determined purposively. Respondents consisted of 35 people who were divided into three scales: 16 respondents for 3-11 (small scale), 10 respondents for 12-20 (medium scale) and 9 respondents for scale > 20 (large scale) . The results showed that the profit sharing system that is implemented in Klambir V Kebun is a profit sharing system for bulls with 50:50 share of the results. The income received by the investor and the farmer is different because in this business breeder farmers who spend for the maintenance of livestock while the investors only provide the livestocks germs. The bigger scale of business that the greater the income. The cattle breeding business with this profit sharing system has a value of r /c ratio > 1, which means the business is feasible to cultivate. The contribution of livestock at each successive scale is 53.40%, 60.22% and 67.79%. Livestock can be categorized as a branch of business because it contributes 30-70% in fulfilling the household income.

scholarly journals Towards a New Proposal for the Time Delay in Gravitational Lensing

2017 ◽  
Author(s):  
Marco Bonici ◽  
Nicola Alchera ◽  
Nicola Maggiore
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Percent Level ◽  
Hubble Constant ◽  
New Physics ◽  
Statistical Fluctuation ◽  
Beyond The Standard Model ◽  
A Value ◽  
The Standard Model

One application of the Cosmological Gravitational Lensing in General Relativity is the measurement of the Hubble constant H_0 using the time delay Delta t between multiple images of lensed quasars. This method has already been applied, obtaining a value of H_0 compatible with that obtained from the SNe 1A, but non compatible with that obtained studying the anisotropies of the CMB. This difference could be a statistical fluctuation or an indication of new physics beyond the Standard Model of Cosmology, so it desirable to improve the precision of the measurements. At the current technological capabilities it is possible to obtain H_0 to a percent level uncertainty, so a more accurate theoretical model could be necessary in order to increase the precision about the determination of H_0. The actual formula which relates Delta t with H_0 is approximated; in this paper we expose a proposal to go beyond the previous analysis and, within the context of a new model, we obtain a more precise formula than that present in the Literature.

scholarly journals The Velocity-Distance Relation and the Hubble Constant for Nearby Groups of Galaxies

1972 ◽  
Vol 44 ◽  
pp. 353-366 ◽  
Author(s):  
G. de Vaucouleurs
Keyword(s):  
Hubble Constant ◽  
Big Bang ◽  
Virgo Cluster ◽  
Apparent Magnitude ◽  
Distance Modulus ◽  
Distance Ratio ◽  
Groups Of Galaxies ◽  
Velocity Magnitude ◽  
Ring Structures ◽  
Distance Relation

The distances of about 100 nearby groups, clouds and clusters of galaxies (δ < 52 Mpc) have been derived from the apparent magnitudes and diameters of the 3 to 5 major members. The linearity of the distance scale was verified for δ < 40 Mpc by comparison with luminosity classifications and diameters of ring structures. The velocity-distance relation of these groups is apparently non-linear for δ < 30 Mpc. The velocity/distance ratio increases from H ≃ 50 to 150 km s−1 Mpc−1 when δ increases from δ ≃ 5 to δ ≃ 25 Mpc. Such local departures from linearity are predicted in condensed regions of an inhomogeneous ‘big bang’ hierarchical model obeying the universal density-radius relation. The galactic apex varies with the apparent magnitude of galaxies used for reference in a manner generally consistent with a model of the Local Supercluster in differential rotation and expansion. The best-fit rotation-expansion constants are ω1R1 = 400 ± 50 km s−1, ε1R1 = 1250 ± 50 km s−1, ż = −250 ± 50 km s−1. The velocity-magnitude relation corrected for solar motion is linear with slope 0.2 in 9 < m < 14, confirming that apart from local departures reflecting the supercluster kinematics the underlying Hubble flow is linear and isotropic. If the distance modulus of the Virgo Cluster is (m - M)0 = 30.5 ± 0.2 the Hubble constant derived from the survey of groups is H0 = (100 ± 10) km s−1 Mpc−1.

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