Download or read book Applications of the Halo Model to Large Scale Structure Measurements of the Luminous Red Galaxies written by Beth Ann Reid and published by . This book was released on 2008 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: The power spectrum of density fluctuations in the evolved universe provides constraints on cosmological parameters that are complementary to cosmic microwave background and other astronomical probes. The Sloan Digital Sky Survey (SDSS) Luminous Red Galaxy (LRG) sample probes a volume of ∼ 3 (Gpc) 3, and systematic errors in modeling the nonlinearities limit our ability to extract information on the shape of the linear power spectrum. There are three main effects that distort the observed power spectrum from the linear power spectrum: nonlinear gravitational evolution, redshift space distortions, and a nonlinear relation between the galaxy density field and the underlying matter density field. In this thesis we introduce a new method to mitigate the latter two distortions and rely on carefully tuned N-body simulations to model the first.
Download or read book Applications of Halo Approach to Non linear Large Scale Structure Clustering written by Asantha Roshan Cooray and published by . This book was released on 2001 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interpreting New Galaxy Large scale Structure Measurements and the Galaxy Halo Connection written by Angela Marie Berti and published by . This book was released on 2020 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: The galaxy distribution in the joint space of stellar mass and star formation rate (SFR) is observed to be bimodal, with distinct star-forming (high SFR) and quiescent (low SFR) populations across many orders of magnitude in stellar mass. The absence of a significant population of intermediate-stage galaxies implies that galaxies tend to cease star formation and become quiescent relatively rapidly, and the physical origins of this rapid quenching are an open question in the field of galaxy evolution. Recent progress in cosmological simulations of dark matter structure evolution, as well as in statistical modeling of how galaxies inhabit dark matter halos, suggest a nuanced coevolutionary relationship between galaxies and the dark matter halos galaxies reside in (the "galaxy-halo connection"), in which the statistical galaxy content of a halo depends on more than halo mass. One class of these galaxy-halo connection models are those that incorporate galaxy assembly bias, a general term for the dependence of galaxy properties on halo properties other than mass. For example, distinct stellar-to-halo mass relations for star-forming and quiescent central galaxies is a form of galaxy assembly bias that could manifest as an anticorrelation of galaxy SFR with clustering amplitude, if the trend is independent of stellar (or halo) mass. In this dissertation we present the first measurements of galactic conformity, or the tendency of neighboring galaxies to share the star formation properties of an adjacent central galaxy, on two-halo scales beyond the local universe (to z~1). We then measure the clustering of isolated galaxies as a proxy for central galaxies, separately for star-forming and quiescent galaxies, to test predictions of galaxy-halo models reflecting galaxy assembly bias. Finally, we measure the joint dependence of clustering on stellar mass and SFR. With mock galaxy catalogs derived from simulations and an empirical galaxy evolution model we quantify and compensate for the effects of systematic biases on these measurements. A parallel theme of this dissertation is demonstrating how existing galaxy surveys beyond the local universe are at the cusp of probing the volumes needed for statistically significant tests of theoretical predictions of various models of galaxy evolution.
Download or read book Applications of Halo Approach to Non Linear Large Scale Structure written by Asantha Cooray and published by LAP Lambert Academic Publishing. This book was released on 2010-06 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present astrophysical applications of the recently popular halo model to describe large scale structure clustering. We formulate the power spectrum, bispectrum and trispectrum of dark matter density field in terms of correlations within and between dark matter halos. The halo approach uses results from numerical simulations and involves a profile for dark matter, a mass function for halos, and a description of halo biasing with respect to the linear density field. This technique can easily be extended to describe clustering of any property of the large scale structure, such as galaxies, baryons and pressure, provided that one formulate the relationship between such properties and dark matter. We discuss applications of the halo model for several observational probes of the local universe involving weak gravitational lensing, thermal Sunyaev-Zel dovich (SZ) effect and the kinetic SZ effect. With respect to weak gravitational lensing, we study the generation of non-Gaussian signals which are potentially observable in galaxy shear data. We study the three and four-point statistics, specifically the bispectrum and trispectrum, of the convergence using the dark matter halo approach.
Download or read book Halo Models of Large Scale Structure written by Asantha Cooray and published by . This book was released on 2002 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Constraining Cosmology with the Halo Occupation Distribution written by Jeremy L. Tinker and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The bias of galaxies with respect to the underlying matter distribution has long been an obstacle to constraining cosmology from measurements of galaxy clustering. Recent advancements in quantifying bias have made it possible to model galaxy clustering from linear to strongly non-linear scales, creating unique methods through which to constrain cosmological parameters that are complementary to more standard, large-scale techniques. These advances are encapsulated in the Halo Occupation Distribution (HOD), in which the bias of galaxies is described at the level of individual dark matter halos. For a given cosmological model, the parameters that specify the number of galaxies that reside in each halo can be constrained by measurements of the galaxy correlation function. With these HOD parameters, the given cosmology model can be tested through a number of other clustering measures that are more sensitive to the underlying dark matter distribution. The clustering measures I investigate in this thesis are mass-to-light ratios, redshift-space distortions, and galaxy void statistics. Mass-to-light ratios of galaxy clusters are uniquely suited to the halo occupation approach because the HOD can specify the number of galaxies in a halo as a function of luminosity. Galaxy bias directly influences the amount of light per unit mass in a cosmological model. I combine HOD models with observational measurements of cluster M/L ratios to test varying cosmologies. Using the HOD to model galaxy clustering in redshift-space allows one to combine data from small and large scales to break the degeneracies that govern the application of models based on linear theory alone. I use numerical simulations to calibrate a new analytic model and apply this model to observations of the redshift-space correlation function from the Sloan Digital Sky Survey. Galaxy voids prove to be insensitive to the details of halo occupation or the cosmological model assumed. This makes void statistics a sensitive test for the underlying assumption of the HOD, which states that galaxy occupation is a function of halo mass only, and not dependent on larger-scale environment. Quantifying the limits of this assumption are necessary for confidence in the constraints the HOD places on cosmology, and for testing our current picture of galaxy formation.
Download or read book The Large scale Three point Correlation Function of SDSS Luminous Red Galaxies written by Felipe A. Marin Perucci and published by . This book was released on 2010 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present new measurements of the redshift-space three-point correlation function (3PCF) of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS). Using the largest dataset to date, the Data Release 7 (DR7) LRGs, and an improved binning scheme compared to previous measurements, we measure the LRG 3PCF on large scales up to & sim; 90 h-1 Mpc, from the mildly non-linear to quasi-linear regimes. Comparing the LRG correlations to the dark matter two- and three-point correlation functions, obtained from N-body simulations we infer linear and nonlinear bias parameters. As expected, LRGs are highly biased tracers of large scale structure, with a linear bias b1 & sim; 2; the LRGs also have a large positive non-linear bias parameter, in agreement with predictions of galaxy population models. The use of the 3PCF to estimate biasing helps to also make estimates of the cosmological parameter sigma8, as well as to infer best-fit parameters of the Halo Occupation Distribution parameters for LRGs. We also use a large suite of public mock catalogs to characterize the error covariance matrix for the 3PCF and compare the variance among simulation results with jackknife error estimates.
Download or read book Post Planck Cosmology written by Cédric Deffayet and published by OUP Oxford. This book was released on 2015-02-05 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the lecture notes of the 100th Les Houches Summer School, which was held in July 2013. These lectures represent a comprehensive pedagogical survey of the frontier of theoretical and observational cosmology just after the release of the first cosmological results of the Planck mission. The Cosmic Microwave Background is discussed as a possible window on the still unknown laws of physics at very high energy and as a backlight for studying the late-time Universe. Other lectures highlight connections of fundamental physics with other areas of cosmology and astrophysics, the successes and fundamental puzzles of the inflationary paradigm of cosmic beginning, the themes of dark energy and dark matter, and the theoretical developments and observational probes that will shed light on these cosmic conundrums in the years to come.
Download or read book Modeling Large Scale Structure from Photometric Surveys written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simulating Large Cosmology Surveys with Calibrated Halo Models written by Stuart Lynn and published by . This book was released on 2011 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis I present a novel method for constructing large scale mock galaxy and halo catalogues and apply this model to a number of important topics in modern cosmology. Traditionally such mocks are created through first evolving a high resolution particle simulation from a set of initial conditions to the present epoch, identifying bound structures and their evolution, and finally applying a semi-analytic prescription for galaxy formation. In contrast to this computationally expensive procedure, I use low resolution simulations to obtain a density field that traces large scale modes. From this background I sample the population statistics of halos: the number of halos which are typically found within a region of a given overdensity, to produce a halo catalogue. From the halo catalogue I then produce galaxies by appealing to the halo model. In this model the expected number of galaxies within a halo and the distribution of their properties is dependent on halo mass alone. By sampling conditional luminosity functions for a number of populations of galaxies, I produce a galaxy catalogue with luminosity and colour properties. The aim of developing algorithm is not to probe the mechanics of galaxy formation in great detail. It is instead intended as a method of rapidly producing mock galaxy and halo catalogues rapidly on modern desktop computers. The approach we will take is to try to distill the minimal algorithm required to achieve this and still provide useful catalogues for observational cosmologists. Both the conditional mass function and conditional luminosity functions required for the algorithm are calibrated from the Millennium Simulation, one of the highest resolution cosmology simulations to date, and its associated semi-analytic catalogues. In Chapter 2 I examine these statistics and provide fits to the quantities of interest. As a test of the method, in Chapter 3 I produce a halo and galaxy catalogue from the same large scale modes as the Millennium Simulation. The clustering statistics of galaxies and halos within this re-simulation are calculated and compared with those of the original. Con dent of the accuracy of the method, in Chapter 4 I populate a number of simulations, each 8 times the volume of the Millennium Simulation, and study the evolution of the Baryon Acoustic Oscillation signal. For each population (dark matter, halos and galaxies) I fit the BAO in the power spectrum to obtain the shift in the BAO peak. In Chapter 5 I extend the algorithm to produce lightcones: simulated skies in which the evolution of the Universe along the line of sight is accounted for. I simulate the geometry and limitations of a major pending survey and calculate the expected clustering signature I expect to see in both. The redshift space distortions induced by peculiar velocities of galaxies along the line of sight are determined and their ability to distinguish between gravity models is also explored. In Chapter 6 I detail a further extension to the algorithm for simulating weak gravitational lensing surveys. I use the analytic 2D surface density pro files of NFW profiles to dress each dark matter halo on a lightcone. The sum of these pro files over the entire population can be used to construct high resolution maps of the convergence. From these maps I calculate the spectrum of the convergence and compare with theoretical predictions. Finally in Chapter 7 I discuss further possible applications and extensions of the algorithm I have developed in this thesis.
Download or read book Advances in Modern Cosmology written by Adnan Ghribi and published by BoD – Books on Demand. This book was released on 2011-08-29 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: The twentieth century elevated our understanding of the Universe from its early stages to what it is today and what is to become of it. Cosmology is the weapon that utilizes all the scientific tools that we have created to feel less lost in the immensity of our Universe. The standard model is the theory that explains the best what we observe. Even with all the successes that this theory had, two main questions are still to be answered: What is the nature of dark matter and dark energy? This book attempts to understand these questions while giving some of the most promising advances in modern cosmology.
Download or read book Cosmological Physics written by J. A. Peacock and published by Cambridge University Press. This book was released on 1999 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and authoritative introduction to contemporary cosmology for advanced undergraduate and graduate students.
Download or read book The Role of Halo Substructure in Gamma Ray Dark Matter Searches written by Miguel A. Sánchez-Conde and published by MDPI. This book was released on 2020-05-28 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important, open research topic today is to understand the relevance that dark matter halo substructure may have for dark matter searches. In the standard cosmological model, halo substructure or subhalos are predicted to be largely abundant inside larger halos, for example, galaxies such as ours, and are thought to form first and later merge to form larger structures. Dwarf satellite galaxies—the most massive exponents of halo substructure in our own galaxy—are already known to be excellent targets for dark matter searches, and indeed, they are constantly scrutinized by current gamma-ray experiments in the search for dark matter signals. Lighter subhalos not massive enough to have a visible counterpart of stars and gas may be good targets as well, given their typical abundances and distances. In addition, the clumpy distribution of subhalos residing in larger halos may boost the dark matter signals considerably. In an era in which gamma-ray experiments possess, for the first time, the exciting potential to put to test the preferred dark matter particle theories, a profound knowledge of dark matter astrophysical targets and scenarios is mandatory should we aim for accurate predictions of dark matter-induced fluxes for investing significant telescope observing time on selected targets and for deriving robust conclusions from our dark matter search efforts. In this regard, a precise characterization of the statistical and structural properties of subhalos becomes critical. In this Special Issue, we aim to summarize where we stand today on our knowledge of the different aspects of the dark matter halo substructure; to identify what are the remaining big questions, and how we could address these; and, by doing so, to find new avenues for research.
Download or read book Mass and Light Correlated with Galaxies on Local and Cosmic Scales written by Ami Choi and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we describe the results of applying weak gravitational lensing techniques to probe the connection between luminous galaxies and the dark matter halos in which they live. Specifically, we study galaxy-shear correlations in the Deep Lens Survey, and we investigate how this function changes with observable galaxy properties such as stellar mass, luminosity, color, and redshift. In Chapter 3, we examine the galaxy-shear correlation function on a large range of scales from small radii where the dominant contribution is from halos associated with individual galaxies to large radii where the dominant contribution is from neighboring galaxies and large-scale structure. We study the lensing signal for galaxies binned by luminosity and find that more luminous galaxies are more massive. More interestingly, the galaxy-shear correlation function shows features consistent with satellite and 2-halo terms from the halo model and cannot be fit with a single power law out to 15 Mpc. We also find more correlated large scale structure mass at lower redshift, consistent with the paradigm of bottom-up hierarchical structure formation. In Chapter 4, we focus on a subset of the survey with ancillary infrared data that allow estimates of stellar mass. We study the lensing signal for galaxies binned by stellar mass and infer the nature and evolution of the relationship between virial mass and stellar mass. We show that stellar mass and virial mass scale such that galaxies with smaller stellar masses also have smaller virial masses. This work has implications for the idea of downsizing, but does not yet have the S/N to provide competitive constraints. In the process of making lensing measurements on the Deep Lens Survey, we have also investigated errors related to the two most important variables: shapes and photometric redshifts. We discuss our findings in the context of the survey characteristics in Chapter 2 and in the simulations section of Chapter 3. While neither the shapes nor the photometric redshifts are perfect, their associated errors can be reasonably controlled such that the results of the scientific analysis discussed above are meaningful. We conclude and comment on future work in Chapter 5. The Appendix contains a useful reference for equations related to lensing formalism and the halo model.
Download or read book Simulations of Galaxy Formation and Large Scale Structure written by Felix Stoehr and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2009-12 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we use the N-body resimulation technique to address aspects of structure formation. In the first chapter we study the influence of the local environment of DM haloes on their properties. In the second chapter we address the so-called "substructure problem" which is one of the major challenges of the CDM model of cosmology. We perform ultra-high resolution simulations of the assembly of a Milky Way type dark matter halo within its full cosmological context and propose a new analytical fitting formula (SWTS) which provides a better fit to the simulated Milky Way halo than the NFW or Moore profiles do. In the third chapter we use our ultra-high resolution simulations to study the possible -ray signal from dark matter annihilation. If such a signal was detected, the nature of the dark matter, the answer to one of the most important questions of modern cosmology, would be known. (urn: nbn: de: bvb:19-16446)"
Download or read book Cosmology and Galaxy Formation written by Rachel Marie Reddick and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary goal of this dissertation is to examine the relationship between galaxies and their dark matter halos. Understanding this relationship is instrumental to using modern galaxy surveys as probes of cosmology and to teasing out the details of galaxy formation. I will focus on methods relating to dark matter only simulations and large area surveys, and the use of galaxy clusters. I begin with an exploration of subhalo abundance matching, a commonly used empirical method for relating galaxies to dark matter halos in dark matter only simulations. The most obvious approach is to simply place the most massive, or most luminous, galaxy into the most massive dark matter halo. Nonetheless, there are several possible variations that I explore within the general class of subhalo abundance matching models. Results from these models are then validated against measurements drawn from the Sloan Digital Sky Survey. These models are used to test a method for obtaining cosmology while marginalizing over the details of the galaxy-halo relationship. This method combines two-point clustering measurements with a measurement of cluster mass and richness to provide constraints on the density of dark matter in the universe. The additional cluster statistics are essential to breaking degeneracies between the galaxy-halo relationship and the cosmology that occur when fitting to the two-point clustering alone. While this method had previously been used in the literature, this dissertation adds by performing a fully consistent analysis of multiple galaxy models, demonstrating that so long as the galaxy-halo connection can be adequately modeled by a halo occupation distribution that the cosmology can be estimated in an unbiased manner. Returning to observations, I examine the clusters obtained using the redMaPPer cluster finder applied to SDSS. The trends found are generally consistent with previous cluster catalogs, but take advantage of the reduced scatter in the mass-richness relationship. The results have significant implications for the formation of clusters, particularly the importance of recent mergers on the galaxy statistics and for redshift evolution. This analysis is also applied to early data from DES, showing the evolution of red cluster galaxies up to z=0.9. Finally, I discuss the potential for future work. This includes application of redMaPPer and the M/N formalism to DES and future surveys, as well as directions for using galaxy cluster catalogs as a tool for understanding the formation of the most massive galaxies and their dark matter halos.
Download or read book Combining Spectroscopic and Imaging Galaxy Surveys for Improved Measurements of Large scale Structure written by Justin Myles and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy imaging surveys represent a promising opportunity for testing cosmological models, but suffer from significant challenges associated with galaxy redshift uncertainty. I present improved techniques for the use of spectroscopic redshifts for measurements of large-scale structure with galaxy imaging surveys. I additionally present the results of the application of these techniques to data from the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES). The results of my work are photometric redshift measurements of the approximately 100 million galaxies comprising the DES Year 3 Weak Lensing Source Galaxy Catalog, constraints on parameters of the Lambda-CDM cosmological model based on the gravitational lensing and clustering of the DES Year 3 source and lens galaxy catalogs, an algorithm for propagating uncertainties that have been measured in simulations to analogous measurements on data, and measurements of the incidence of projection effects in optically detected clusters of galaxies. I argue that continued development of the methods I have worked on is a promising path toward a conclusive test of Lambda-CDM with galaxy surveys.
