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Models for structure formation attempt to predict the power spectrum of density perturbations in the present universe from the initial power spectrum and the nature of dark matter. Observational constraints on the power spectrum at…

Astrophysics · Physics 2007-05-23 K. Subramanian , T. Padmanabhan

We present a comprehensive model to predict the rate of spectroscopic confusion in HI surveys, and demonstrate good agreement with the observable confusion in existing surveys. Generically the action of confusion on the HI mass function was…

Astrophysics of Galaxies · Physics 2015-06-24 Michael G. Jones , Emmanouil Papastergis , Martha P. Haynes , Riccardo Giovanelli

Empirical researchers often estimate spillover effects by fitting linear or non-linear regression models to sampled network data. We show that common sampling schemes bias these estimates, potentially upwards, and derive biased-corrected…

General Economics · Economics 2025-09-23 Kieran Marray

The EFAR project has measured peculiar motions in two distant volumes of the universe using Fundamental Plane (FP) distances for 85 clusters with cz=6000-15000 km/s. The scatter in distance about the FP is observed to be 20% per galaxy for…

The power spectrum of density fluctuations measured from galaxy redshift surveys provides important constraints on models for the formation of large-scale structure. I review current results for the 3-D power spectrum and examine the…

Astrophysics · Physics 2007-05-23 Michael S. Vogeley

We use a simple analytic model to compute the angular correlation function of clusters identified in upcoming thermal SZ effect surveys. We then compute the expected fraction of close pairs of clusters on the sky that are also close along…

Astrophysics · Physics 2009-11-07 Antonaldo Diaferio , Adi Nusser , Naoki Yoshida , Rashid A. Sunyaev

Many surveys use maximum-likelihood (ML) methods to fit models when extracting photometry from images. We show these ML estimators systematically overestimate the flux as a function of the signal-to-noise ratio and the number of model…

Instrumentation and Methods for Astrophysics · Physics 2020-03-25 Stephen K. N. Portillo , Joshua S. Speagle , Douglas P. Finkbeiner

Considering the matter power spectrum covariance matrix, it has recently been found that there is a potentially dominant effect on mildly non-linear scales due to power in modes of size equal to and larger than the survey volume. This {\it…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Roland de Putter , Christian Wagner , Olga Mena , Licia Verde , Will Percival

We study the large-scale velocity fields traced by galaxy clusters in numerical simulations of a box of side 960 $h^{-1}$ Mpc, and compare them with available data on real clusters. In order to test the reliability of the simulations, which…

We propose a new model of cluster growth according to which the probability that a new unit is placed in a point at a distance $r$ from the city center is a Gaussian with mean equal to the cluster radius and variance proportional to the…

Physics and Society · Physics 2007-05-23 M. Pica Ciamarra , A. Coniglio

The use of galaxy clusters as cosmological probes hinges on our ability to measure their masses accurately and with high precision. Hydrostatic mass is one of the most common methods for estimating the masses of individual galaxy clusters,…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-12 Kaylea Nelson , Erwin T. Lau , Daisuke Nagai , Douglas H. Rudd , Liang Yu

The frequency distributions of sizes of ``clouds" and ``clumps" within clouds are significantly flatter for extinction surveys than for CO spectral line surveys, even for comparable size ranges. A possible explanation is the blocking of…

Astrophysics · Physics 2009-10-28 J. Scalo , A. Lazarian

In the presence of strong clustering, low-resolution surveys measure the summed contributions of groups of sources within the beam. The counts of bright intensity peaks are therefore shifted to higher flux levels compared to the counts of…

We present an algorithm for inferring the dynamical mass of galaxy clusters directly from their respective phase-space distributions, i.e. the observed line-of-sight velocities and projected distances of galaxies from the cluster centre.…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 Doogesh Kodi Ramanah , Radosław Wojtak , Zoe Ansari , Christa Gall , Jens Hjorth

The impact of biasing schemes on the clustering of tracers of the large-scale structure is analytically studied in the weakly nonlinear regime. For this purpose, we use the one-loop approximation of the integrated perturbation theory…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-20 Takahiko Matsubara , Vincent Desjacques

Large galaxies are thought to form hierarchically, from the accretion and disruption of many smaller galaxies. Such a scenario should naturally lead to galactic phase-space distributions containing some degree of substructure. We examine…

Astrophysics · Physics 2009-11-11 Brian M. Yencho , Kathryn V. Johnston , James S. Bullock , Katherine L. Rhode

In this paper, we aim to monitor the flow of people in large public infrastructures. We propose an unsupervised methodology to cluster people flow patterns into the most typical and meaningful configurations. By processing 3D images from a…

Computer Vision and Pattern Recognition · Computer Science 2019-02-12 João Carvalho , Manuel Marques , João P. Costeira

The surface mass density of a cluster of galaxies, and thus its total mass, can be estimated from its lens magnification. The magnification can be determined from the variation in number counts of its background galaxies. In the weak…

Astrophysics · Physics 2009-10-30 Eelco van Kampen

Evolution and abundance of the large-scale structures we observe today, such as clusters of galaxies, is sensitive to the statistical properties of dark matter primordial density fluctuations, which is assumed to follow a Gaussian…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-29 Ziad Sakr , Damien Houguenague , Alain Blanchard