相关论文: Cosmicflows-3: Two Distance$-$Velocity Calculators
The velocity dispersion of galaxies on small scales ($r\sim1h^{-1}$ Mpc), $\sigma_{12}(r)$, can be estimated from the anisotropy of the galaxy-galaxy correlation function in redshift space. We apply this technique to ``mock-catalogs''…
Analyses of peculiar velocity surveys face several challenges, including low signal--to--noise in individual velocity measurements and the presence of small--scale, nonlinear flows. I will present three new analyses that attempt to address…
In this paper, we review recent and ongoing work by our group on numerical simulations of relativistic jets. Relativistic outflows in Astrophysics are related to dilute, high energy plasmas, with physical conditions out of the reach of…
We describe the results of a search for galaxies with large (> 350 km/s) velocity dispersions. The largest systems we have found appear to be the extremes of the early-type galaxy population: compared to other galaxies with similar…
This work is a continuation of a previous publication {Thieberger and Spiegel,astro-ph/0204485} concerning the use of two dimensional catalogues in unraveling the large scale distribution of galaxies. Since the data in two-dimensional…
Time delay and velocity estimation has been a widely studied subject in the context of signal processing, with applications in many different fields of physics. The velocity of fluctuation structures is typically estimated as the distance…
The cosmic web that characterizes the large-scale structure of the Universe can be quantified by a variety of methods. For example, large redshift surveys can be used in combination with point process algorithms to extract long curvilinear…
We present a study of the dynamics of triplets of galaxies. In particular we focus on properties that are directly comparable with observations: e.g., velocity dispersion, mean harmonic radius, and virial mass. We find, for example, that…
Peculiar velocities are the motions of galaxies due to the gravitational influence of large-scale structure, and thus are an important cosmological probe of the underlying matter density field. In recent years the number of surveys designed…
The neutral hydrogen properties of 1,822 galaxies are being studied with the Green Bank 100m and the Parkes 64m telescopes as part of the 'Cosmic Flows' program. Observed parameters include systemic velocities, profile line widths, and…
Our velocity with respect to the cosmic frame of rest leads to a dipole in the number count distribution of galaxies. The dipole depends on the source spectrum, which is usually assumed to be a power law, $S(\nu) \propto \nu^{-\alpha}$ and…
Bulk flows of galaxies moving with respect to the cosmic microwave background are well established observationally and seen in the most recent LCDM simulations. With the aid of an idealised Gadget-2 simulation, we show that void asymmetries…
Complex networks are a useful tool to investigate various phenomena in social science, economics, and logistics. Node Vector Distance (NVD) is an emerging set of techniques allowing us to estimate the distance and correlation between…
We study the possibility of using correlations between spatial modulations in the observed luminosity distribution of galaxies and the underlying density field as a cosmological probe. Considering redshift ranges, where magnification…
In order to measure distances with minimal systematics using the correlation between galaxy luminosities and rotation rates it is necessary to adhere to a strict and tested recipe. We now derive a measure of rotation from a new…
Cosmicflows-3 distances and inferred peculiar velocities of galaxies have permitted the reconstruction of the structure of over and under densities within the volume extending to 0.05c. This study focuses on the under dense regions,…
A list of radial velocities, HI line widths and peculiar velocities of 1327 galaxies from the RFGC catalogue has been compiled using actual observations and literature data. The list can be used for studying bulk motions of galaxies,…
I summarize both observational and theoretical developments in the last few years in measuring and understanding the large-scale velocity field of galaxies, with special attention to the bulk flow, or average peculiar velocity, within…
The accurate classification of galaxies in large-sample astrophysical databases of galaxy clusters depends sensitively on the ability to distinguish between morphological types, especially at higher redshifts. This capability can be…
Distance transformation is an image processing technique used for many different applications. Related to a binary image, the general idea is to determine the distance of all background points to the nearest object point (or vice versa). In…