scholarly journals Large-scale peculiar velocities through the galaxy luminosity function at z ~ 0.1

2014 ◽  
Vol 11 (S308) ◽  
pp. 332-335
Author(s):  
Martin Feix ◽  
Adi Nusser ◽  
Enzo Branchini
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Zero Point ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
The Galaxy ◽  
Linear Velocity Field ◽  
Density Perturbations ◽  
Velocity Moments ◽  
Galaxy Luminosity Function

AbstractPeculiar motion introduces systematic variations in the observed luminosity distribution of galaxies. This allows one to constrain the cosmic peculiar velocity field from large galaxy redshift surveys. Using around half a million galaxies from the SDSS Data Release 7 at z ~ 0.1, we demonstrate the applicability of this approach to large datasets and obtain bounds on peculiar velocity moments and σ8, the amplitude of the linear matter power spectrum. Our results are in good agreement with the ΛCDM model and consistent with the previously reported ~ 1% zero-point tilt in the SDSS photometry. Finally, we discuss the prospects of constraining the growth rate of density perturbations by reconstructing the full linear velocity field from the observed galaxy clustering in redshift space.

scholarly journals Measuring the cosmic bulk flow with 6dFGSv

2014 ◽  
Vol 11 (S308) ◽  
pp. 336-339 ◽  
Author(s):  
Christina Magoulas ◽  
Christopher Springob ◽  
Matthew Colless ◽  
Jeremy Mould ◽  
John Lucey ◽  
...  
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Distortion Parameter ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
Redshift Surveys ◽  
Luminous Matter ◽  
The Galaxy ◽  
Space Distortion

AbstractWhile recent years have seen rapid growth in the number of galaxy peculiar velocity measurements, disagreements remain about the extent to which the peculiar velocity field - a tracer of the large-scale distribution of mass - agrees with both ΛCDM expectations and with velocity field models derived from redshift surveys. The 6dF Galaxy Survey includes peculiar velocities for nearly 9 000 early-type galaxies (6dFGSv), making it the largest and most homogeneous galaxy peculiar velocity sample to date. We have used the 6dFGS velocity field to determine the amplitude and scale of large-scale cosmic flows in the local universe and test standard cosmological models. We also compare the galaxy density and peculiar velocity fields to establish the distribution of dark and luminous matter and better constrain key cosmological parameters such as the redshift-space distortion parameter.

scholarly journals Spiral Galaxies and the Peculiar Velocity Field

1996 ◽  
Vol 168 ◽  
pp. 183-191 ◽  
Author(s):  
Riccardo Giovanelli ◽  
Martha P. Haynes ◽  
Pierre Chamaraux ◽  
Luiz N. Da Costa ◽  
Wolfram Freudling ◽  
...  
Keyword(s):  
Velocity Field ◽  
Reference Frame ◽  
Large Scale ◽  
Local Group ◽  
Spiral Galaxies ◽  
Density Parameter ◽  
Compelling Evidence ◽  
Homogeneous Sample ◽  
Peculiar Velocity ◽  
Peculiar Velocities

We report results of a redshift-independent distance measurement survey that extends to all sky and out to a redshift of approximately 7500 km s−1. Tully–Fisher (TF) distances for a homogeneous sample of 1600 late spiral galaxies are used to analyze the peculiar velocity field. We find large peculiar velocities in the neighborhood of superclusters, such as Perseus–Pisces (PP) and Hydra–Centaurus, but the main clusters embedded in those regions appear to be virtually at rest in the CMB reference frame. We find no compelling evidence for large-scale bulk flows, whereby the Local Group, Hydra–Cen and PP would share a motion of several hundred km s−1with respect to the CMB. Denser sampling in the PP region allows a clear detection of infall and backflow motions, which can be used to map the mass distribution in the supercluster and to obtain an estimate of the cosmological density parameter.

scholarly journals Relativistic approach to the kinematics of large-scale peculiar motions

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Eleni Tsaprazi ◽  
Christos G. Tsagas
Keyword(s):  
Velocity Field ◽  
Growth Rates ◽  
Large Scale ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory ◽  
Peculiar Velocity ◽  
Linear Evolution ◽  
Peculiar Velocities ◽  
Bulk Motion ◽  
Relativistic Approach

Abstract We consider the linear kinematics of large-scale peculiar motions in a perturbed Friedmann universe. In so doing, we take the viewpoint of the “real” observers that move along with the peculiar flow, relative to the smooth Hubble expansion. Using relativistic cosmological perturbation theory, we study the linear evolution of the peculiar velocity field, as well as the expansion/contraction, the shear and the rotation of the bulk motion. Our solutions show growth rates considerably stronger than those of the earlier treatments, which were mostly Newtonian. On scales near and beyond the Hubble radius, namely at the long-wavelength limit, peculiar velocities are found to grow as $$a^2$$a2, in terms of the scale factor, instead of the Newtonian $$a^{1/2}$$a1/2-law. We attribute this to the fact that, in general relativity, the energy flux, triggered here by the peculiar motion of the matter, also contributes to the local gravitational field. In a sense, the bulk flow gravitates, an effect that has been bypassed in related relativistic studies. These stronger growth-rates imply faster peculiar velocities at horizon crossing and higher residual values for the peculiar-velocity field. Alternatively, one could say that our study favours bulk peculiar flows larger and faster than anticipated.

scholarly journals The peculiar velocity field up to z ∼ 0.05 by forward-modelling Cosmicflows-3 data

2019 ◽  
Vol 488 (4) ◽  
pp. 5438-5451 ◽  
Author(s):  
R Graziani ◽  
H M Courtois ◽  
G Lavaux ◽  
Y Hoffman ◽  
R B Tully ◽  
...  
Keyword(s):  
Velocity Field ◽  
Initial Conditions ◽  
Selection Function ◽  
Data Sets ◽  
Forward Modelling ◽  
Local Universe ◽  
Peculiar Velocity ◽  
Peculiar Velocities ◽  
The Galaxy ◽  
Distance Indicators

Abstract A hierarchical Bayesian model is applied to the Cosmicflows-3 catalogue of galaxy distances in order to derive the peculiar velocity field and distribution of matter within z ∼ 0.054. The model assumes the ΛCDM model within the linear regime and includes the fit of the galaxy distances together with the underlying density field. By forward modelling the data, the method is able to mitigate biases inherent to peculiar velocity analyses, such as the Homogeneous Malmquist bias or the lognormal distribution of peculiar velocities. The statistical uncertainty on the recovered velocity field is about 150 km s−1 depending on the location, and we study systematics coming from the selection function and calibration of distance indicators. The resulting velocity field and related density fields recover the cosmography of the Local Universe which is presented in an unprecedented volume of our Universe 10 times larger than previously reached. This methodology opens the doors to reconstruction of initial conditions for larger and more accurate constrained cosmological simulations. This work is also preparatory to larger peculiar velocity data sets coming from Wallaby, TAIPAN, or LSST.

scholarly journals A slight excess of large-scale power from moments of the peculiar velocity field

2011 ◽  
Vol 414 (1) ◽  
pp. 621-626 ◽  
Author(s):  
E. Macaulay ◽  
H. Feldman ◽  
P. G. Ferreira ◽  
M. J. Hudson ◽  
R. Watkins
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Peculiar Velocity ◽  
Slight Excess

scholarly journals Beyond the Galaxy Luminosity Function

2004 ◽  
Vol 21 (4) ◽  
pp. 344-351 ◽  
Author(s):  
Simon Driver
Keyword(s):  
Surface Brightness ◽  
Luminosity Function ◽  
Large Scale ◽  
Evolutionary Processes ◽  
Multivariate Distributions ◽  
Independent Investigation ◽  
Current State ◽  
The Galaxy ◽  
Galaxy Population ◽  
Galaxy Luminosity Function

AbstractWith the advent of large-scale surveys (i.e. Legacy Surveys) it is now possible to start looking beyond the galaxy luminosity function (LF) to more detailed statistical representations of the galaxy population, i.e multivariate distributions. In this review I first summarise the current state-of-play of the B-band global and cluster LFs and then briefly present two promising bivariate distributions: the luminosity–surface brightness plane (LSP) and the colour–luminosity plane (CLP). In both planes galaxy bulges and galaxy disks form marginally overlapping but distinct distributions, indicating two key formation/evolutionary processes (presumably merger and accretion). Forward progress in this subject now requires the routine application of reliable bulge–disk decomposition codes to allow independent investigation of these two key components.

Sign in / Sign up

Export Citation Format

Share Document