Download or read book Tools for Cosmology Combining Data from Photometric and Spectroscopic Surveys written by Sujeong Lee (Ph. D. in physics) and published by . This book was released on 2019 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmic acceleration is the most surprising discovery in modern history. While the phenomenon has been proven by a plethora of cosmological observations, the underlying mechanism is still a mystery. There have been various attempts to understand the driver of cosmic acceleration in a form of "dark energy" or "modified gravity", but none of these has compelling evidence. This thesis contains my PhD research projects dedicated to find the origin of cosmic acceleration. In Chapter 2, I describe the DES-CMASS (DMASS) galaxy sample constructed from images taken from the Dark Energy Survey (DES). The sample is designed for a joint analysis of the existing BAO and RSD measurements from BOSS using the CMASS galaxy sample and a galaxy-galaxy lensing measurement from DES. We show that DMASS successfully replicates CMASS in many ways, such as by comparing galaxy bias, angular correlation functions, and redshifts. Chapter 3 describes the DES Y1 analysis for extended cosmological models focusing on modified gravity (MG), which I contributed. DES Y1 shear measurement significantly improves the existing MG constraints. We show that the resulting MG constraints are consistent with general relativity. In the latter part of the chapter, I forecast the detection of MG parameters for DMASS to demonstrate the capability of DMASS to achieve tighter constraints by cancelling galaxy bias. Finally, in Chapter 4, we study the information content of the three-dimensional galaxy correlation function and power spectrum when realistic scale cuts are applied. We find that two estimators are complementary to each other and combining the two yields small improvement for joint constraints.
Download or read book Multi probe Cluster Cosmology Analyses with Photometric Surveys written by Chun-Hao To and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The universe we live in is expanding faster and faster. This phenomenon called cosmic acceleration is one of the most puzzling cosmological discoveries in the past 25 years: even the least exotic explanation requires a new pervasive energy component in our universe (called dark energy). Despite the mysterious nature of dark energy, a model ($\Lambda$CDM) based on Einstein's general relativity, a cosmological constant (a specific form of dark energy), and slowly moving dark matter, seems to be able to describe a variety of observations from the high- to low-redshift universe. To understand the nature of dark energy and to test the $\Lambda$CDM paradigm, ambitious cosmological surveys, such as the Dark Energy Survey (DES), the Dark Energy Spectroscopic Instrument (DESI), the Rubin Observatory's Legacy Survey of Space and Time (LSST), and the Roman Space Telescope, aim to precisely and robustly measure cosmic structure and its evolution via various cosmological probes, such as weak gravitational lensing, galaxy clustering, and other techniques. Combining multiple cosmological probes (known as multi-probe analyses) provides precise and robust cosmological constraints. Galaxy clustering, weak gravitational lensing, and abundances of galaxy clusters each are sensitive to different aspects of cosmic structure formation and are affected by different astrophysical and observational uncertainties. Thus, their combination is expected to be more precise and robust than any of the probe alone. Among these probes, the abundances and spatial distribution of galaxy clusters, which are associated with the highest peaks in the matter density field, provide powerful probes of cosmic structure and its evolution. This thesis presents original research that improves our understandings of the universe by observations of galaxy clusters. In the three self-contained projects, I (1) develop and validate methods for combining cluster abundances and two-point correlation functions, (2) perform the first blind cosmology analysis on combining cluster abundances, weak gravitational lensing, and galaxy clustering using data taken in the first season (DES-Y1) of the Dark Energy Survey, and (3) quantify the connections between red galaxies and their host dark matter halos by modeling luminosity functions of galaxies in galaxy clusters. While these three projects have already advanced our understandings of the cosmos, they also serve as an example of how one can use millions of clusters expected to be detected with the upcoming surveys in 2020s to improve our knowledge of the universe. These opportunities are also discussed in this thesis.
Download or read book Astronomical Data Analysis Software and Systems XIV written by Patrick L. Shopbell and published by . This book was released on 2005 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic Failures in Photometric Redshift Calibration written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We use N-body-spectro-photometric simulations to investigate the impact of incompleteness and incorrect redshifts in spectroscopic surveys to photometric redshift training and calibration and the resulting effects on cosmological parameter estimation from weak lensing shear-shear correlations. The photometry of the simulations is modeled after the upcoming Dark Energy Survey and the spectroscopy is based on a low/intermediate resolution spectrograph with wavelength coverage of 5500{\AA} {\lambda}
Download or read book Seeing in the Dark written by Eric Michael Huff and published by . This book was released on 2012 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Statistical weak lensing by large-scale structure { cosmic shear { is a promising cosmological tool, which has motivated the design of several large upcoming astronomical surveys. This Thesis presents a measurement of cosmic shear using coadded Sloan Digital Sky Survey (SDSS) imaging in 168 square degrees of the equatorial region, with r 2 and median redshift of zmed = 0.52. These coadds were generated using a new rounding kernel method that was intended to minimize systematic errors in the lensing measurement due to coherent PSF anisotropies that are otherwise prevalent in the SDSS imaging data. Measurements of cosmic shear out to angular separations of 2 degrees are presented, along with systematics tests of the catalog generation and shear measurement steps that demonstrate that these results are dominated by statistical rather than systematic errors. Assuming a cosmological model corresponding to WMAP7 (Komatsu et al., 2011) and allowing only the amplitude of matter fluctuations [sigma]8 to vary, the best-t value of the amplitude of matter fluctuations is [sigma]8=0.636+0.109-0.154 (1[sigma]); without systematic errors this would be [sigma]8=0.636+0.099-0.137 (1[sigma]). Assuming a flat & LambdaCDM model, the combined constraints with WMAP7 are [sigma]8=0.784super>+0.028-0.026 (1[sigma]). The 2[sigma] error range is 14 percent smaller than WMAP7 alone. Aside from the intrinsic value of such cosmological constraints from the growth of structure, some important lessons are identied for upcoming surveys that may face similar issues when combining multi-epoch data to measure cosmic shear. Motivated by the challenges faced in the cosmic shear measurement, two new lensing probes are suggested for increasing the available weak lensing signal. Both use galaxy scaling relations to control for scatter in lensing observables. The first employs a version of the well-known fundamental plane relation for early type galaxies. This modified "photometric fundamental plane" replaces velocity dispersions with photometric galaxy properties, thus obviating the need for spectroscopic data. We present the first detection of magnication using this method by applying it to photometric catalogs from the Sloan Digital Sky Survey. This analysis shows that the derived magnication signal is comparable to that available from conventional methods using gravitational shear. We suppress the dominant sources of systematic error and discuss modest improvements that may allow this method to equal or even surpass the signal-to-noise achievable with shear. Moreover, some of the dominant sources of systematic error are substantially different from those of shear-based techniques. The second outlines an idea for using the optical Tully-Fisher relation to dramatically improve the signal-to-noise and systematic error control for shear measurements. The expected error properties and potential advantages of such a measurement are proposed, and a pilot study is suggested in order to test the viability of Tully-Fisher weak lensing in the context of the forthcoming generation of large spectroscopic surveys.
Download or read book Highlights of Astronomy Volume 14 written by Karel van der Hucht and published by Cambridge University Press. This book was released on 2008-01-21 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recording the proceedings of the IAU XXVI General Assembly, this volume of the IAU Highlights of Astronomy covers virtually all aspects of modern astrophysics as discussed by 2400 participants from 73 countries. Notably, the common aspects of astrophysical phenomena known to exist in widely differing interstellar environments is thoroughly examined, providing fertile cross correlation from one specialisation to another. This text highlights the importance of the triennial IAU General Assemblies in bringing together the work of observers and theoreticians in widely different fields, but working towards a common goal: understanding the physics of the Universe. Together with the Proceedings of the IAU Symposia 235-240, this volume examines all of the astrophysics presented at the General Assembly.
Download or read book Fundamentals of Astronomy written by Cesare Barbieri and published by CRC Press. This book was released on 2020-11-25 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a broad overview of foundational concepts, this second edition of Fundamentals of Astronomy covers topics ranging from spherical astronomy to reference systems, and celestial mechanics to astronomical photometry and spectroscopy. It expounds arguments of classical astronomy that provided the foundation for modern astrometry, whilst presenting the latest results of the very-long-baseline interferometry (VLBI) radio technique, optical interferometers and satellites such as Hipparcos and GAIA, and recent resolutions of the IAU and IERS regarding precession, forced and free nutation, and Earth figure and rotation. Concepts of general relativity are explored, such as the advance of Mercury’s perihelion, light deflection and black holes, in addition to the physical properties, orbits, and ephemerides of planets, comets and asteroids with an extension to visual binary stars orbital reconstruction. Extrasolar planets are also discussed, with reference to radial velocity and transits measurements by ground and space telescopes. Basic concepts of astronomical photometry, spectroscopy and polarimetry are given, including the influence of the terrestrial atmosphere. Classical works, such as Hipparchus, are mentioned in order to provide a flavor of the historical development of the field. It is an ideal textbook for undergraduate and graduate students studying astronomy, astrophysics, mathematics, and engineering. Supplementary and explanatory notes provide readers with references to additional material published in other literature and scientific journals, whilst solved and unsolved exercises allow students to review their understanding of the material. Features: Provides an introductory vision of arguments from spherical astronomy to celestial mechanics to astronomical photometry and spectroscopy Presents the information at an introductory level without sacrificing scientific rigor Fully updated throughout with the latest results in the field
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 Neutrino Mass written by Guido Altarelli and published by Springer. This book was released on 2004-02-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews the current state of knowledge of neutrino masses and the related question of neutrino oscillations. After an overview of the theory of neutrino masses and mixings, detailed accounts are given of the laboratory limits on neutrino masses, astrophysical and cosmological constraints on those masses, experimental results on neutrino oscillations, the theoretical interpretation of those results, and theoretical models of neutrino masses and mixings. The book concludes with an examination of the potential of long-baseline experiments. This is an essential reference text for workers in elementary-particle physics, nuclear physics, and astrophysics.
Download or read book Photometric Calibrations written by Robert L. Booker and published by . This book was released on 1987 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modern Cosmology written by Scott Dodelson and published by Academic Press. This book was released on 2003-03-13 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced text for senior undergraduates, graduate students and physical scientists in fields outside cosmology. This is a self-contained book focusing on the linear theory of the evolution of density perturbations in the universe, and the anisotropiesin the cosmic microwave background.
Download or read book New Horizons for Observational Cosmology written by A. Cooray and published by IOS Press. This book was released on 2015-01-06 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our understanding of the universe has been revolutionized by observations of the cosmic microwave background, the large-scale structure of the universe, and distant supernovae. These studies have shown that we are living in a strange universe: 96% of the present day energy density of the universe is dominated by so-called dark matter and dark energy. But we still do not know what dark matter and dark energy actually are. This book presents lectures from the 186th Course in the Enrico Fermi International School of Physics entitled New Horizons for Observational Cosmology, held in Varenna, Italy, in July 2013. Topics covered at this school included: cosmic microwave background anisotropies; galaxy clustering; weak lensing; dark energy; dark matter; inflation; modified gravity; neutrino physics; reionization; galaxy formation; and first stars. The anticipated release of Planck data at the end of 2014 will provide a more complete view of temperature anisotropy of the cosmic microwave background, and the reporting of other important results is also expected soon. These new data will undoubtedly address fundamental questions about the universe. This book prepares the ground for future work which may answer some of these exciting questions.
Download or read book Data Analysis in Cosmology written by Vicent J. Martinez and published by Springer. This book was released on 2009-07-09 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: The amount of cosmological data has dramatically increased in the past decades due to an unprecedented development of telescopes, detectors and satellites. Efficiently handling and analysing new data of the order of terabytes per day requires not only computer power to be processed but also the development of sophisticated algorithms and pipelines. Aiming at students and researchers the lecture notes in this volume explain in pedagogical manner the best techniques used to extract information from cosmological data, as well as reliable methods that should help us improve our view of the universe.
Download or read book Statistics Data Mining and Machine Learning in Astronomy written by Željko Ivezić and published by Princeton University Press. This book was released on 2014-01-12 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: As telescopes, detectors, and computers grow ever more powerful, the volume of data at the disposal of astronomers and astrophysicists will enter the petabyte domain, providing accurate measurements for billions of celestial objects. This book provides a comprehensive and accessible introduction to the cutting-edge statistical methods needed to efficiently analyze complex data sets from astronomical surveys such as the Panoramic Survey Telescope and Rapid Response System, the Dark Energy Survey, and the upcoming Large Synoptic Survey Telescope. It serves as a practical handbook for graduate students and advanced undergraduates in physics and astronomy, and as an indispensable reference for researchers. Statistics, Data Mining, and Machine Learning in Astronomy presents a wealth of practical analysis problems, evaluates techniques for solving them, and explains how to use various approaches for different types and sizes of data sets. For all applications described in the book, Python code and example data sets are provided. The supporting data sets have been carefully selected from contemporary astronomical surveys (for example, the Sloan Digital Sky Survey) and are easy to download and use. The accompanying Python code is publicly available, well documented, and follows uniform coding standards. Together, the data sets and code enable readers to reproduce all the figures and examples, evaluate the methods, and adapt them to their own fields of interest. Describes the most useful statistical and data-mining methods for extracting knowledge from huge and complex astronomical data sets Features real-world data sets from contemporary astronomical surveys Uses a freely available Python codebase throughout Ideal for students and working astronomers
Download or read book Software for Photometric Astronomy written by Silvano Ghedini and published by . This book was released on 1982 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Knowledge Discovery in Big Data from Astronomy and Earth Observation written by Petr Skoda and published by Elsevier. This book was released on 2020-04-10 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knowledge Discovery in Big Data from Astronomy and Earth Observation: Astrogeoinformatics bridges the gap between astronomy and geoscience in the context of applications, techniques and key principles of big data. Machine learning and parallel computing are increasingly becoming cross-disciplinary as the phenomena of Big Data is becoming common place. This book provides insight into the common workflows and data science tools used for big data in astronomy and geoscience. After establishing similarity in data gathering, pre-processing and handling, the data science aspects are illustrated in the context of both fields. Software, hardware and algorithms of big data are addressed. Finally, the book offers insight into the emerging science which combines data and expertise from both fields in studying the effect of cosmos on the earth and its inhabitants. - Addresses both astronomy and geosciences in parallel, from a big data perspective - Includes introductory information, key principles, applications and the latest techniques - Well-supported by computing and information science-oriented chapters to introduce the necessary knowledge in these fields
Download or read book Outskirts of Galaxy Clusters IAU C195 written by International Astronomical Union. Colloquium and published by Cambridge University Press. This book was released on 2004-12-16 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the International Astronomical Union Colloquium no. 195, held in Torino, Italy in 2004. The meeting investigated the formation of galaxies within a full cosmological context, focusing on the outer regions of galaxy clusters. The observed correlation of optical and radio properties of galaxies with their environment indicates that the formation and evolution of galaxies is intimately linked to the formation of large scale structure. With chapters written by leading authorities in the field, this timely volume investigates the role of the environment in determining the properties of galaxies. It describes the distribution of matter and galaxies on the largest scales in the Universe, the processes of cluster and galaxy formation, their role and interplay. This is a valuable collection of review articles for professional astronomers.
