The peculiar Jeans length

  title={The peculiar Jeans length},
  author={Christos G. Tsagas},
Large-scale bulk flows are commonplace in the universe. This means that observers living in typical galaxies, like our Milky Way, do not follow the mean universal expansion, but have peculiar velocities relative to it. Using relativistic linear cosmological perturbation theory, we show that bulk peculiar motions introduce a characteristic length scale. The latter is analogous to the familiar Jeans length and marks the threshold below which the linear kinematics, as seen by observers living… Expand
1 Citations

Figures and Tables from this paper

The deceleration parameter in “tilted” Friedmann universes: Newtonian vs relativistic treatment
Although bulk peculiar motions are commonplace in the universe, most theoretical studies either bypass them, or take the viewpoint of the idealised Hubble-flow observers. As a result, the role ofExpand


Cosmic flows on 100 h−1 Mpc scales: standardized minimum variance bulk flow, shear and octupole moments
The low order moments, such as the bulk flow and shear, of the large scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. In practice, however,Expand
Cosmic flows in the nearby universe from Type Ia supernovae
Peculiar velocities are one of the only probes of very large scale mass density fluctuations in the nearby Universe. We present new ‘minimal variance’ bulk flow measurements based upon the ‘FirstExpand
Evidence for anisotropy of cosmic acceleration
Observations reveal a “bulk flow” in the local Universe which is faster and extends to much larger scales than are expected around a typical observer in the standard ΛCDM cosmology. This is expectedExpand
Power Spectrum Estimation from Peculiar Velocity Catalogues
The peculiar velocities of galaxies are an inherently valuable cosmological probe, pro- viding an unbiased estimate of the distribution of matter on scales much larger than the depth of the survey.Expand
The peculiar velocity field in the local supercluster
A general method of estimating the peculiar velocity field expected, under the gravitational instability picture, around the outer parts of a mass concentration like a cluster of galaxies is derivedExpand
Planck intermediate results - XIII. Constraints on peculiar velocities
Using Planck data combined with the Meta Catalogue of X-ray detected Clusters of galaxies (MCXC), we address the study of peculiar motions by searching for evidence of the kinetic Sunyaev-ZeldovichExpand
The 6dF Galaxy Survey: bulk flows on 50-70 h(-1) Mpc scales
We measure the bulk flow of the local Universe using the 6dF Galaxy Survey peculiar velocity sample (6dFGSv), the largest and most homogeneous peculiar velocity sample to date. 6dFGSv is aExpand
Relativistic cosmology and large-scale structure
General relativity marked the beginning of modern cosmology and it has since been at the centre of many of the key developments in this field. In the present review, we discuss theExpand
Non-comoving cosmology
One of the fundamental assumptions of the standard $\Lambda$CDM cosmology is that, on large scales, all the matter-energy components of the Universe share a common rest frame. This seems natural forExpand
Probing cosmic isotropy with a new X-ray galaxy cluster sample through the LX–T scaling relation
The isotropy of the late Universe is an assumption greatly used in astronomy. However, many studies have recently reported deviations from isotropy with a definitive conclusion yet to be made. New,Expand