scholarly journals Non-Uniformities in the Hubble Flow: Results from a Survey of Elliptical Galaxies

1987 ◽  
Vol 124 ◽  
pp. 223-227
Author(s):  
Roger L. Davies ◽  
David Burstein ◽  
Alan Dressler ◽  
S. M. Faber ◽  
Donald Lynden-Bell ◽  
...  
Keyword(s):  
Local Group ◽  
Elliptical Galaxies ◽  
Microwave Background ◽  
Peculiar Velocities ◽  
Group Motion ◽  
Fisher Relation ◽  
Distance Estimator ◽  
Hubble Flow ◽  
Good Agreement

We have used a new distance estimator for elliptical galaxies to determine the peculiar velocities, with respect to a uniform Hubble flow, of approximately 400 galaxies. The relative distances of five clusters in common with those of Aaronson et al. (1981, 1986), based on the infrared Tully-Fisher relation for spirals, are in good agreement.We do not see the reflex of the Local Group motion with respect to the microwave background out to recession velocities of 6000 km s−1. Rather, the frame of elliptical galaxies appears to be moving with respect to the microwave background with a velocity of 600 km s−1 towards 1 = 312°, b = +6°. This motion is consistent with a re-analysis of the Rubin et al. (1976) data on the magnitude-diameter relation for ScI galaxies and with the nearby and cluster samples of Aaronson et al. (1982, 1986).

scholarly journals The Motion of the Local Group of Galaxies with Respect to the Background of Galaxies

1983 ◽  
Vol 104 ◽  
pp. 255-258
Author(s):  
R. D. Davies
Keyword(s):  
Large Scale ◽  
Local Group ◽  
Microwave Background ◽  
Optical Studies ◽  
Group Motion ◽  
Gravitational Influence ◽  
Nearby Galaxies ◽  
Peculiar Motion ◽  
The Universe ◽  
Hubble Flow

A measurement of the motion of the Local Group of galaxies through the Universe provides an indication of their peculiar motion relative to the Hubble flow consequent upon the gravitational influence of the local large scale mass inhomogeneities. This motion can be measured either relative to the cosmic microwave background at z ∼ 1000 or relative to the background or nearby (z ∼ 0.01) galaxies. The interpretation of published measurements is subject to some uncertainty. As an example, the Local Group motion derived from optical studies of nearby galaxies (Rubin et al. 1976) differs from that derived from radio frequency measurements of the dipole anisotropy in the microwave background. (Boughn et al. 1981, Gorenstein & Smoot 1981).

scholarly journals Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density field

2014 ◽  
Vol 11 (S308) ◽  
pp. 318-321
Author(s):  
Michael J. Hudson ◽  
Jonathan Carrick ◽  
Stephen J. Turnbull ◽  
Guilhem Lavaux
Keyword(s):  
Cosmic Microwave Background ◽  
Local Group ◽  
Cosmological Parameters ◽  
Density Field ◽  
Bulk Flow ◽  
Microwave Background ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
Best Fit ◽  
Good Agreement

AbstractUsing redshifts from the 2M++ redshift compilation, we reconstruct the density of galaxies within 200 h−1 Mpc, and compare the predicted peculiar velocities Tully-Fisher and SNe peculiar velocities. The comparison yields a best-fit value of β ≡ Ωm0.55/b* = 0.431 ± 0.021, suggesting Ωm0.55σ8,lin = 0.401 ± 0.024, in good agreement with other probes. The predicted peculiar velocity of the Local Group from sources within the 2M++ volume is 540 ± 40 km s−1, towards l = 268° ± 4°, b = 38° ± 6°, which is misaligned by only 10° with the Cosmic Microwave Background dipole. To account for sources outside the 2M++ volume, we fit simultaneously for β* and an external bulk flow in our analysis. The external bulk flow has a velocity of 159 ± 23 km s−1 towards l = 304° ± 11°, b6° ± 13°.

scholarly journals The Tully-Fisher Relation and its Application to the Distance Scale

1983 ◽  
Vol 6 ◽  
pp. 269-282 ◽  
Author(s):  
M. Aaronson
Keyword(s):  
Group Velocity ◽  
Deceleration Parameter ◽  
Local Group ◽  
Hubble Constant ◽  
Distance Scale ◽  
Expansion Rate ◽  
Distance Indicator ◽  
Fisher Relation ◽  
Hubble Flow ◽  
Local Value

AbstractThe Tully-Fisher relation applied in the infrared appears to be the best global distance indicator presently available for determining the expansion rate and deviations from uniform Hubble flow. In this article recent results obtained using the IR/H I method are reviewed. A Virgo-directed Local Group velocity of about 300 km s–1 is indicated (implying a local value for the deceleration parameter qo ~ 0.05 – 0.1) along with a “best guess” value for the Hubble Constant of 85 km s-1 Mpc-1.

scholarly journals Cosmological bulk flow in the QCDM model: (in)consistency with ΛCDM

2021 ◽  
Vol 504 (1) ◽  
pp. 1304-1319
Author(s):  
A Salehi ◽  
M Yarahmadi ◽  
S Fathi ◽  
Kazuharu Bamba
Keyword(s):  
Cold Dark Matter ◽  
Bulk Flow ◽  
Microwave Background ◽  
Local Universe ◽  
Peculiar Velocities ◽  
Large Bulk ◽  
Likelihood Analysis ◽  
Type Ia ◽  
The Universe ◽  
Good Agreement

ABSTRACT We study the bulk flow of the local universe with Type Ia supernova data (a compilation of Union2 and Pantheon data) in the spatially flat homogeneous and isotropic space–time. In particular, we take the so-called QCDM models, which consist of cold dark matter (CDM) and a Q-component described by a scalar field with its self-interactions determined by an exponential potential. We use different cumulative redshift slices of the Union2 and Pantheon catalogues. A maximum-likelihood analysis of peculiar velocities confirms that, at low redshifts 0.015 < z < 0.1, the bulk flow is moving in the $l=272^{+17}_{-17}, b=33^{+12}_{-12}$, and $302^{+20}_{-20},3^{+10}_{-10}$ directions with $v _\mathrm{bulk} = 225^{+38}_{-35}$ and $246^{+64}_{-46}$ km s−1 for the Pantheon and Union2 data respectively, in good agreement with the direction of the cosmic microwave background dipole and with a number of previous studies at 1σ. However, for high redshifts 0.1 < z < 0.2, we get $v _\mathrm{bulk} = 708^{+110}_{-110}$ and $v_\mathrm{bulk}=1014^{+86}_{-114}\,\text{km\,s}^{-1}$ towards l = 318 ± 10°, b = −15 ± 9° and $l=254^{+16}_{-14},\ b=6^{+7}_{-10}$ for the Pantheon and Union2 data respectively. This indicates that for low redshifts our results are approximately consistent with the ΛCDM model; however, for high redshifts they disagree with ΛCDM and support the results of those studies that report a large bulk flow for the universe.

Spiral Galaxies, Elliptical Galaxies and the Large-Scale Velocity Field Within 3500 Km/s of the Local Group

1988 ◽  
pp. 177-180 ◽  
Author(s):  
David Burstein ◽  
Roger L. Davies ◽  
Alan Dressler ◽  
S. M. Faber ◽  
Donald Lynden-Bell ◽  
...  
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Local Group ◽  
Spiral Galaxies ◽  
Elliptical Galaxies

scholarly journals Variable Stars in Dwarf Spheroidal Galaxies

1973 ◽  
Vol 21 ◽  
pp. 35-48
Author(s):  
Steven Van Agt
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Elliptical Galaxies ◽  
Variable Stars ◽  
Dwarf Spheroidal Galaxies ◽  
Theoretical Predictions ◽  
History Of ◽  
Set Up ◽  
Theoretical Considerations ◽  
Spheroidal Galaxies

Interest in dwarf spheroidal galaxies is motivated by a number of reasons; an important one on the occasion of this colloquium is the abundance of variable stars. The theory of stellar evolution and stellar pulsations is now able to predict from theoretical considerations characteristic properties of variable stars in the colour-magnitude diagram (Iben, 1971). By observing the variable stars in the field, and in as wide a selection of objects as possible, more insight can be obtained into the history of the oldest members of our Galaxy (the globular clusters) and of the dwarf spheroidal galaxies in the Local Group. It is worthwhile to explore the spheroidal galaxies as observational tests for the theoretical predictions of conditions in space away from our Galaxy. The numbers of variable stars in the dwarf spheroidal galaxies are such that we may expect well-defined relations to emerge once reliable magnitude sequences have been set up, the variable stars found, and their periods determined. Six dwarf spheroidal galaxies are presently known in the Local Group within a distance of 250 kpc. In Table I, which lists members of the Local Group, they are at the low-luminosity end of the sequence of elliptical galaxies (van den Bergh, 1968).

scholarly journals Galaxy Motions in the Nearby Universe

1996 ◽  
Vol 168 ◽  
pp. 143-155
Author(s):  
John P. Huchra
Keyword(s):  
Virgo Cluster ◽  
Velocity Fields ◽  
Density Field ◽  
Current Status ◽  
Microwave Background ◽  
History Of ◽  
Measured Flow ◽  
Nearby Galaxies ◽  
Cluster 2 ◽  
Hubble Flow

In this paper we review the history of the search for and study of the motions of nearby galaxies with respect to the Hubble Flow. The current status of the field is that (1) convincing infall has been detected into dense clusters, especially the Virgo cluster, (2) the microwave background direction is moderately well aligned with the measured flow nearby but not apparently on larger scales, and (3) there is good but not perfect consistency between the nearby density fields and velocity fields. Particular problems exist in the different Ω's required to fit the density field derived from optically selected and IRAS (60μ) selected galaxy samples.

scholarly journals The Dark Halo – Spheroid Conspiracy

2012 ◽  
Vol 8 (S295) ◽  
pp. 208-208
Author(s):  
Rhea-Silvia Remus ◽  
Andreas Burkert ◽  
Klaus Dolag ◽  
Peter H. Johansson ◽  
Thorsten Naab ◽  
...  
Keyword(s):  
Elliptical Galaxies ◽  
Total Density ◽  
Dark Halo ◽  
Coma Cluster ◽  
Density Profiles ◽  
Stellar Component ◽  
Strong Lensing ◽  
The Galaxy ◽  
Good Agreement

AbstractObservational results from strong lensing and dynamical modeling indicate that the total density profiles of early-type galaxies are close to isothermal, i.e. ρtot ∝ rγ with γ ≈ −2. To understand the origin of this universal slope we study a set of simulated spheroids formed in cosmological hydrodynamical zoom-in simulations (see Oser et al. 2010 for more details). We find that the total stellar plus dark matter density profiles of all our simulations on average can be described by a power law with a slope of γ ≈ −2.1, with a tendency towards steeper slopes for more compact, lower mass ellipticals, while the total intrinsic velocity dispersion is flat for all simulations, independent of the values of γ. Our results are in good agreement with observations of Coma cluster ellipticals (Thomas et al. 2007) and results from strong lensing (Sonnenfeld et al. 2012). We find that for z ≳ 2 the majority of the stellar build-up occurs through in-situ star formation, i.e. the gas falls to the center of the galaxy and forms stars, causing the galaxy to be more compact and thus the stellar component to be more dominant. As a result, the total density slopes at z ≈ 2 are generally steeper (around γ ≈ −3). Between z = 2 and z = 0 galaxies grow mostly through dry merging, with each merging event shifting the slope more towards γ ≈ −2. We conclude from our simulations that the steepness of the slope of present day galaxies is a signature of the importance of mostly dry mergers in the formation of an elliptical, and suggest that all elliptical galaxies will with time end up in a configuration with a density slope of γ ≈ −2. For a more detailed analysis with a larger sample of simulations see Remus et al. (2013).

scholarly journals Elliptical Galaxies and Large-Scale Velocity Flows

1988 ◽  
Vol 130 ◽  
pp. 169-176
Author(s):  
S. M. Faber ◽  
David Burstein ◽  
Roger L. Davies ◽  
Alan Dressler ◽  
Donald Lynden-Bell ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Flow Model ◽  
Local Group ◽  
Elliptical Galaxies ◽  
Local Velocity ◽  
Velocity Flow ◽  
Large Scale Flow ◽  
Double Cluster

Motions of nearby elliptical galaxies reveal a large-scale velocity flow relative to cosmic rest towards the point 1=307±10, b = 9±10. The data are fit best by a two-component flow model. The smaller component is due to Virgo, which induces a velocity at the Local Group of 250 km/s. The main flow is due to a more massive concentration located a distance of 4350±350 km/s towards 1=307, b=9, which induces a local velocity here of 570±60 km/s. This larger component falls off away from the mass concentration roughly as r−1. The Centaurus double cluster and its neighbors are in the direction of the mass concentration but are in the foreground and are falling into it. Galaxy counts, radial velocity surveys, and the motions of nearby spirals are consistent with the above model. The IRAS dipole results are less clear but may also be consistent. There is evidence that the distant mass concentration is non-spherical, with the Centaurus cloud a substantial sub-condensation in the foreground. The formal agreement of the large-scale flow with biased (b=2) cold dark matter is low, but the simple methods used so far to assess this are uncertain. The main weakness of the present data in comparing to theory is the fact that they do not penetrate far enough to show the velocity field on all sides of the mass concentration. Sphericity and total extent of the flow are therefore still unknown.

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