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Topic: Peculiar velocities

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	Homework 7 Discussion (Site not responding. Last check: 2007-10-03)
		Peculiar velocities refer to an individual galaxy's motion with respect to the overall Hubble expansion.
		Peculiar velocities correspond to motions with respect to comoving coordinates.
		Peculiar velocities are really what we would regard as ordinary velocities.
	www.astro.virginia.edu /~jh8h/astr348/h7info.html (426 words)

	Nat' Academies Press, High-Energy Astrophysics: American and Soviet Perspectives/Proceedings from the U.S.-U.S.S.R. ...
		We separate peculiar velocities and distances using an iterative procedure: galaxies are initially assumed to be at their redshift distances (V-0), and equation (2) is used to make a first estimate of the peculiar velocity field.
		It is indeed a remarkable fact that is able to reproduce the qualitative nature of the velocity Dow field, perhaps the first direct indication that peculiar velocities are generated by gravity, and that galaxies at least approximated trace the mass distribution of the underlying dark matter.
		The true peculiar velocities were perturbed by a gaussian "error" with a standard deviation of 15% of the true distance to mimic the observational situation.
	www.nap.edu /openbook.php?record_id=1851&page=356 (3851 words)

	AboutNEMD.html
		The peculiar velocity of any particle is then defined as the instantaneous difference of v -i gy from the harmonic representation of the periodic velocity field.
		In this case the streaming velocity is associated with the instantaneous long wavelength velocity modes while the peculiar velocity is assumed to be given by the short wavelength modes.
		The p i are peculiar momenta, defined in terms of the peculiar velocities, i.e., the velocities of the particles with respect to the (local) fluid velocity ux(y)=gy.
	www.anu.edu.au /Physics/summerschool/NEMD/AboutNEMD.html (3856 words)

	Encyclopedia: Peculiar velocities (Site not responding. Last check: 2007-10-03)
		The term peculiar velocity refers to the components of a receding galaxy's velocity that cannot be explained by Hubble's law.
		In the real Universe, a galaxy is not alone, but it is typically found in a group or a cluster, ranging in size from less than a dozen to several thousands.
		A more accurate estimate can be done taking the average velocity of a group of galaxies: the peculiar velocities, assumed essentially random, will cancel each other, leaving a much more accurate measurement.
	www.nationmaster.com /encyclopedia/Peculiar-velocities (320 words)

	Mark III Catalog of Galaxy Peculiar Velocities: Distances for Groups and Single Galaxies Homogeneous Velocity-Distance ...
		Bytes 69-74 (HelioV) is the heliocentric radial velocity of the galaxy, from sources as quoted by Willick (1991, Ph.D. thesis) Bytes 76-81 (CMB_V) is the radial velocity of the galaxy relative to the Cosmic Microwave Background, using the COBE heliocentric-to-CMB correction of 368.6 km/sec towards l=264.7deg, b=48.2deg.
		Bytes 75-81 (CMB_V) is the radial velocity of the galaxy relative to the Cosmic Microwave Background, using the COBE heliocentric-to-CMB correction of 368.6 km/sec towards l=264.7deg, b=48.2deg.
		CMB_V is the radial velocity of the galaxy relative to the Cosmic Microwave Background, using the COBE heliocentric-to-CMB correction of 368.6 km/sec towards l=264.7deg, b=48.2deg.
	www.cs.wisc.edu /niagara/data/nasa/7198.xml (11320 words)

	About Me
		These galaxies and clusters were selected to permit measurement of peculiar motions of galaxies in two specific regions of space.
		Furthermore, Faber and Dressler have now identified both elliptical and spiral galaxies which show evidence of retarded Hubble velocities that are beyond the region upon which the local flow appears to be centered, though this remains controversial.
		With this number of galaxies and clusters, peculiar motions of 1,000 km s-1 can be detected at >3-s accuracy on scale sizes down to 20 h-1 Mpc.
	www.physics.unc.edu /~mcmahan/astr31/about.htm (745 words)

	6dF Survey Plan
		The primary observational goal of the second phase of the 6dF survey is to measure peculiar velocities for an all-sky sample of galaxies.
		Note that the velocity field is a very direct constraint on the mass distribution, since (i) it constrains the mass power spectrum as opposed to the galaxy power spectrum, and (ii) it is less affected by non-linearities than the density field.
		By comparison, almost all the current generation of peculiar velocity observations are consistent with all the alternative models shown in the figure.
	www2.iap.fr /users/gam/6dF/6dF_survey_plan.html (4963 words)

	Результаты научных работ 25 (Site not responding. Last check: 2007-10-03)
		After recombination of hydrogen the one of probable mechanism of formation CMBR fluctuations there can be a scattering by small density inhomogeneities if they have peculiar velocities and opacity for electromagnetic emission.
		Peculiar velocities of various spatial scale are predicted in all models of evolution.
		This estimate approximately by 3 order reduces a range of estimations available in different works and it is quite reasonable from the point of view kinetic of molecules in nonequilibrium condition at presence of gradients of velosity and density.
	www.sao.ru /hq/lrs/res25a.html (403 words)

	Dynamical Masses 2
		The significance of these peculiar velocities is that in order for them to have persisted over the lifetime of the Universe, they must be driven by something.
		The peculiar velocities are due to mass concentrations which pull on things causing deviations from the Hubble flow.
		It is clear that the size of the perturbation (the size of the peculiar velocities) will depend upon how much mass pulls on the object.
	jersey.uoregon.edu /~imamura/209/apr24/dynamic2.html (942 words)

	The Distribution of Galaxies in Space (Site not responding. Last check: 2007-10-03)
		The fact the peculiar velocities exist at all is immediately evident from observations of the microwave background, which show a strong dipole.
		The velocity of the LG was though to be generated partly by infall into Virgo, and also by infall into Hydra-Centaurus, which is near the apex of the microwave dipole.
		The velocity field was subsequently confirmed by observations of spirals via TF, and the local field was though to be moderately well described by a combination of infall into the GA and Virgo, though the amplitude of the latter is still debated.
	ganymede.nmsu.edu /holtz/a616/ay616/node19.html (3113 words)

	Velocity Field Matches Gravity Field
		as an estimate of the small-scale component of the radial peculiar velocity not describable by linear theory.
		Although the gravity predictions are derived independently from the observed peculiar velocities, the similarity of the two is remarkable.
		Velocity dipole patterns that match the gravitational dipole signature have been detected in several other surveys (e.g., Riess, Press, and Kirshner 1995b; da Costa et al.
	ecf.hq.eso.org /~ralbrech/sepdec97apjl/975467.html (2976 words)

	kSZ substructure
		A gas velocity map overlayed on the emission-weighted temperature map of the cluster at z=0.
		The density-weighted average radial velocities of gas (solid) and dark matter (dashed) within a sphere centered on the minimum of cluster potential for clusters at z=0.43 (top) and z=0 (bottom) through the same three orthogonal projections (from left to right) shown in Fig.3.
		The density-weighted average velocities of gas and dark matter agree remarkably well beyond ~500kpc (approximately half the cluster virial radius), particularly for the relaxed z=0 cluster; however, the discrepancies are significant in the central region of the cluster.
	astro.uchicago.edu /~daisuke/Research/ARTcode/ksz.html (444 words)

	[No title]
		This extra velocity component, which is unrelated to the distance of the galaxy, creates problems when we want to know how close one galaxy is to another.
		For example, a cluster at z=0.050 could contain members with peculiar velocities of +- 1000 km/s which will spread the cluster out in redshift space: it will look as if some of the cluster members are not in the cluster because they have redshifts of 0.047 or 0.053.
		Similarly, an isolated galaxy at z=0.045 could have a peculiar velocity of 1000 km/s, increasing its redshift and throwing it into the cluster galaxy sample.
	www.astro.washington.edu /ben/a511/density.html (568 words)

	Saleem Zaroubi's fields of interest in Cosmology & Medical Physics
		In contrast, the peculiar velocities of galaxies are presumably honest tracers of the motion of the dark matter.
		The value of b inferred from comparing the density map, as constructed from galaxy redshift catalogs, with density map reconstructed from peculiar velocity catalogs is about 1; whilethe value of b estimated from a comparison of the radial velocities obtained from redshift catalogs and from peculiar velocity catalogs is about 0.5.
		Hoffman (Jerusalem), I have applied this technique to reconstruct the smoothed density and peculiar velocity fields from the SEcat galaxy peculiar velocity catalog and compared them to the density and 3D peculiar velocity field reconstructed from the PSCz galaxy redshift catalog.
	www.astro.rug.nl /~saleem/research.html (2337 words)

	dark matter
		It has been known since the late 1920s that the universe is expanding and that this so-called Hubble expansion is the dominant factor controlling the speed of galaxies in the distant universe.
		These deviations are called "peculiar velocities", but Sandage pointed out that galaxies in our vicinity - those lying just beyond our "Local Group" of the Milky Way and its immediate neighbours - showed abnormally low peculiar velocities.
		Governato and his colleagues have now incorporated dark energy into their computer model, and find that it does indeed match extremely well the observed peculiar velocities for galaxies in regions resembling the Local Group and just beyond.
	www.meta-religion.com /Astronomy/Other_subjects/dark_matter.htm (403 words)

	Peculiar velocities and the Local Supercluster (Site not responding. Last check: 2007-10-03)
		The bulk of the velocity field in the local supercluster can be fit by assuming infall onto the Virgo Cluster (see the image on left), however there are still unexplained motions which can be fit by other more distance attractors - hence a multiattractor model offers the best simple solution to fit the velocity field.
		This work showed that a good understanding of the local velocity field is necessary to understand the properties of local galaxies, providing some of the justification for the topic of my thesis.
		For this work we constructed mock catalogues of HI surveys to investigate the impact neglecting peculiar velocities can have on measurements of the HI mass function.
	astrosun.tn.cornell.edu /~masters/lsc.html (481 words)

	[No title] (Site not responding. Last check: 2007-10-03)
		Peculiar Velocities for Galaxies in the Great Wall 1: The Data
		We use the 20% linewidth relation for a study of the peculiar velocity field in a separate paper (Dell'Antonio et al.
		We analyze the peculiar velocity field in the vicinity of the Great Wall (GW) using a sample of 172 spiral galaxies with reliable IRTF distance estimates (Dell'Antonio et al.
	cfa-www.harvard.edu /cfa/ep/preprint/julaug96/4380.html (481 words)

	Ravi K. Sheth's Homepage
		Non-gaussian CMB temperature fluctuations from peculiar velocities of clusters.
		Linear and nonlinear contributions to pairwise peculiar velocities.
		The distribution of pairwise peculiar velocities in the nonlinear regime.
	home.fnal.gov /~sheth (787 words)

	Max Tegmark's cosmology library: sz (Site not responding. Last check: 2007-10-03)
		The expected 1-sigma errors of peculiar velocity measurements for the XBACs cluster sample (Ebeling 1993) for our fiducial standard cosmological model (Omega=1, h=0.5, Omega_b=0.06) and a beam size of 8' and 4', respectively.
		We have investigated the possibility of inferring peculiar velocities for clusters of galaxies from the Doppler shift of scattered cosmic microwave background (CMB) photons.
		Individual peculiar velocities will be measurable only for a few fast moving clusters at intermediate redshift unless cosmic fluctuations are smaller than most standard cosmological scenarios predict.
	space.mit.edu /home/tegmark/sz.html (355 words)

	Cosmology Presentation (Site not responding. Last check: 2007-10-03)
		Although redshift (velocity) corresponds to true distance according to the Hubble Law, small peculiar velocities not associated with the Hubble flow can cause distortions in redshift space.
		The Fingers-of-God effect is attributed to random velocity dispersions in galaxy clusters that deviate a galaxy's velocity from pure Hubble flow, stretching out a cluster in redshift space.
		This differs from the Fingers-of-God in that the peculiar velocities are coherent, not random, towards the central mass, though the effect is very subtle.
	astron.berkeley.edu /~louis/astro228/redshift.html (614 words)

	Alan Campbell Peel's Research Homepage (Site not responding. Last check: 2007-10-03)
		Peculiar velocities trace the density field in a great, non-biased way (at least in linear theory!).
		Recent excitement about using galaxy cluster peculiar velocities is motivated by their possible uses to reconstruct (large modes of) the real-space potential.
		paper details how many cluster velocities we need from a given observational volume to determine modes based on limitations from (1) confusion between dark matter and gas velocities and (2) what we call the "undersampling noise" in that cluster-cluster separation is larger than the pre-collapse radius of a typical cluster.
	www.damtp.cam.ac.uk /user/ap416 (1487 words)

	[No title] (Site not responding. Last check: 2007-10-03)
		Precise determinations of the image positions in quad gravitational lenses using VLBI can be used to measure the transverse velocity of the lens galaxy and the observer.
		By measuring the dipole of the proper motions in an ensemble of lenses we can set limits on the deviation of the inertial frame defined by the lenses from that defined by the CMB dipole and estimate the Hubble constant.
		The residual proper motions after subtracting the dipole probe the evolution of peculiar velocities with redshift and can be used to estimate the density parameter
	cfa-www.harvard.edu /ep/preprint/janfeb96/4262.html (214 words)

	Are there any galaxies that have a blue-shift?
		So, in a nutshell, if a galaxy's peculiar velocity is toward us and larger than its Hubble recessional velocity, then its light will appear blueshifted.
		This is possible for galaxies that are nearby like Andromeda, but as galaxies get farther away, their Hubble velocities dwarf any peculiar velocities they might have.
		The velocities are in the order of hundreds of kilometers per second and in regions close enough to our own galaxy where the Hubble expansion results in less outward expansion than this, the galaxies' peculiar velocities (if they are large enough and sufficiently towards us) can overcome that expansion, resulting in a blue-shift.
	www.physlink.com /Education/AskExperts/ae384.cfm (534 words)

	NIRI SV Obs 17
		Measuring Peculiar Velocities and Omega in the Sculptor Void
		Peculiar Velocities around a void can be used to constrain Omega directly (assuming that motions are generated by gravitational instabilities).
		To make a useful measurement of the velocity field around a void, we need to (a) find a sufficiently large, empty void, and (b) measure accurate distances to a number of galaxies throughout the region to adequately sample peculiar velocities.
	www.gemini.edu /sciops/instruments/niri/SVobs/NIRISVobs17.html (255 words)

	Australian National University EPrints2 Archive - The peculiar motions of early-type galaxies in two distant regions - ... (Site not responding. Last check: 2007-10-03)
		We present peculiar velocities for 85 clusters of galaxies in two large volumes at distances between 6000 and 15000kms-1 in the directions of Hercules-Corona Borealis and Perseus-Pisces-Cetus (the EFAR sample).
		These velocities are based on Fundamental Plane (FP) distance estimates for early-type galaxies in each cluster.
		We measure the bulk motions of the sample volumes using the 50 clusters with the best-determined peculiar velocities.
	eprints.anu.edu.au /archive/00001126 (403 words)

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