相关论文: Optimal Galaxy Distance Estimators
Using a set of 73 numerically simulated galaxy clusters, we have characterised the statistical and physical biases for three velocity dispersion and mass estimators, namely biweight, gapper and standard deviation, in the small number of…
This paper studies the effect of the distance choice in radial (non-average) statistical tools used for fractal characterization of galaxy distribution. After reviewing the basics of measuring distances of cosmological sources, various…
We determine the values of parameters of an N-body model for the Galaxy developed by Fux via comparison with an unbiased, homogeneous sample of OH/IR stars. Via Monte-Carlo simulation, we find the plausibilities of the best-fitting models,…
The number density and redshift evolution of optically selected galaxy clusters offer an independent measurement of the amplitude of matter fluctuations, $S_8$. However, recent results have shown that clusters chosen by the redMaPPer…
In the warm dark matter scenario, the Press-Schechter formalism is valid only for galaxy masses greater than the "velocity dispersion cut-off". In this work we extend the predictions to masses below the velocity dispersion cut-off, and…
Determining star cluster distances is essential to analyse their properties and distribution in the Galaxy. In particular it is desirable to have a reliable, purely photometric distance estimation method for large samples of newly…
Estimates of cosmological parameters using galaxy clusters have the scatter in the observable at a given mass as a fundamental parameter. This work computes the amplitude of the scatter for a newly introduced mass proxy, the product of the…
We develop an improved mass tracer for clusters of galaxies from optically observed parameters, and calibrate the mass relation using weak gravitational lensing measurements. We employ a sample of ~ 13,000 optically-selected clusters from…
For 100 years since galaxies were found to be flying apart from each other, astronomers have been trying to determine how fast. The expansion, characterized by the Hubble constant, H0, is confused locally by peculiar velocities caused by…
Accurate distances are key to obtaining intrinsic properties of astronomical objects such as luminosity or size. Globular clusters (GCs) follow a well-defined relation between their absolute magnitudes and internal stellar velocity…
Dust has long been identified as a barrier to measuring inherent galaxy properties. However, the link between dust and attenuation is not straightforward and depends on both the amount of dust and its distribution. Herschel imaging of…
Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with…
We study the alignment of radio galaxies axes using the FIRST catalogue. we impose several cuts in order to select the candidates which are most likely to be free of systematic bias. In our study we primarily focus on testing for alignment…
We present a method for deriving a smoothed estimate of the peculiar velocity field of a set of galaxies with measured circular velocities $\eta\equiv {\rm log} \Delta v$ and apparent magnitudes $m$. The method is based on minimizing the…
I describe a general formalism for galaxy biasing (Dekel & Lahav 1998) and its application to measurements of beta (=Omega^0.6/b), e.g. via direct comparisons of light and mass and via redshift distortions. The linear and deterministic…
We have investigated, using both a theoretical and an empirical approach, the frequency of low redshift galaxy-galaxy lensing systems in which the signature of weak lensing might be directly detectable. We find good agreement between these…
We propose the use of robust, Bayesian methods for estimating extragalactic distance errors in multi-measurement catalogs. We seek to improve upon the more commonly used frequentist propagation-of-error methods, as they fail to explain both…
The scatter in the galaxy size versus stellar mass (Mstar) relation gets largely reduced when, rather than the half-mass radius Re, the size at a fixed surface density is used. Here we address why this happens. We show how a reduction is to…
Measuring distances to galaxies, determining their chemical composition, investigating the nature of their stellar populations and the absorbing properties of their interstellar medium are fundamental activities in modern extragalactic…
Using multiple tracers of large-scale structure allows to evade the limitations imposed by sampling variance for some parameters of interest in cosmology. We demonstrate the optimal way of carrying out a multitracer analysis in a galaxy…