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.

Download or read book A Pan Chromatic View of Clusters of Galaxies and the Large Scale Structure written by Manolis Plionis and published by Springer. This book was released on 2008-02-17 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reviews presented in this volume cover a huge range of cluster of galaxies topics. Readers will find the book essential reading on subjects such as the physics of the ICM gas, the internal cluster dynamics, and the detection of clusters using different observational techniques. The expert chapter authors also cover the huge advances being made in analytical or numerical modeling of clusters, weak and strong lensing effects, and the large scale structure as traced by clusters.

Download or read book Robust Measurements of the Large scale Clustering of Galaxy Survey Data written by Mehdi Rezaie and published by . This book was released on 2021 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-scale structure (LSS) of the Universe traced by galaxies is one of the essential probes of dark energy, dark matter, neutrino masses, nature of gravity, and statistical properties of primordial fluctuations. The clustering of primordial fluctuations from the cosmic microwave background to LSS provides a standard ruler test to study the dynamics of the cosmic expansion and the mysterious dark energy. Additionally, LSS can be utilized to reconstruct the primordial features and the statistical properties of the initial conditions of the Universe. Future galaxy redshift surveys are designed to extend aggressively to higher redshifts to reach a greater cosmic volume for improved precision as well as for studying the dynamics of dark energy further back in time. For instance, the Dark Energy Spectroscopic Instrument (DESI) will observe millions of galaxies and quasars, producing a three–dimensional map probing the Universe across 10 billion light-years or out to the redshift of 3.5. With enormous data volume, we can address fundamental cosmological problems with higher statistical precision, but such analyses demand more advanced methods and theoretical modeling of systematics. Emmission line galaxies (ELGs) are star-forming galaxies that populate the high redshift universe and therefore are promising tracers for LSS that will be targeted in future galaxy surveys. Quasi-stellar objects or quasars (QSOs) are distant galaxies that host massive black holes and the accreting black holes make these objects bright enough to be used as targets for high redshift galaxy surveys. However, the measurements of such targets are subject to various observational systematic effects that are still largely unknown. Mitigating such effects is crucial for deriving unbiased and precise cosmological constraints. This dissertation addresses the challenge of observational systematics by comparing the results of various approaches. My dissertation consists of three parts: In the first part, I establish a deep learning approach to model and mitigate the effects of observational systematics in the large-scale clustering of galaxies. I implement, validate, and apply the method to log-normal mock datasets as well as ELGs from real imaging data that will be used for targeting in DESI. I demonstrate that the nonlinear approach based on neural networks reduces observational systematics more efficiently than conventional linear regression. In the second part, I enhance the methodology for the final sample of quasars from the extended Baryon Acoustic Oscillation Survey (eBOSS). I compare the performance of different mitigation techniques and show that there is no signature of nonlinear systematics in the data. In the third part, I use the resulting improved data to constrain the initial conditions of the Universe. The methods and tools developed in this dissertation pave the path of probing the large-scale structure using data from the upcoming next generation of galaxy redshift surveys such as DESI and Euclid. This thesis presents my contribution as a member of the DESI and eBOSS collaborations.

Download or read book Optimizing Spectroscopic and Photometric Galaxy Surveys written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The combination of multiple cosmological probes can produce measurements of cosmological parameters much more stringent than those possible with any individual probe. We examine the combination of two highly correlated probes of late-time structure growth: (i) weak gravitational lensing from a survey with photometric redshifts and (ii) galaxy clustering and redshift space distortions from a survey with spectroscopic redshifts. We choose generic survey designs so that our results are applicable to a range of current and future photometric redshift (e.g. KiDS, DES, HSC, Euclid) and spectroscopic redshift (e.g. DESI, 4MOST, Sumire) surveys. Combining the surveys greatly improves their power to measure both dark energy and modified gravity. An independent, non-overlapping combination sees a dark energy figure of merit more than 4 times larger than that produced by either survey alone. The powerful synergies between the surveys are strongest for modified gravity, where their constraints are orthogonal, producing a non-overlapping joint figure of merit nearly 2 orders of magnitude larger than either alone. Our projected angular power spectrum formalism makes it easy to model the cross-correlation observable when the surveys overlap on the sky, producing a joint data vector and full covariance matrix. We calculate a same-sky improvement factor, from the inclusion of these cross-correlations, relative to non-overlapping surveys. We find nearly a factor of 4 for dark energy and more than a factor of 2 for modified gravity. The exact forecast figures of merit and same-sky benefits can be radically affected by a range of forecasts assumption, which we explore methodically in a sensitivity analysis. We show that that our fiducial assumptions produce robust results which give a good average picture of the science return from combining photometric and spectroscopic surveys.

Download or read book New Horizons from Multi Wavelength Sky Surveys written by Brian J. McLean and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large area sky surveys are now a reality in the radio, IR, optical and X-ray passbands. In the next few years, new surveys using optical, UV and IR mosaic cameras with high throughput digital detectors will expand the dynamic range and accuracy of photometry and astrometry of objects over a significant fraction of the entire sky. Parallel X-ray and radio surveys over the same areas will produce astronomical image and spectroscopic databases of unprecedented size and quality. The combined data sets will provide significant new constraints on star formation, stellar dynamics, Galactic structure, the evolution of galaxies and large scale structure, as well as new opportunities to identify rare objects in the solar system and the Galaxy. Large area surveys have formidable data acquisition, processing, archiving, and data distribution demands and this meeting provided a forum for sharing experiences amongst workers specializing in different wavebands as well as discussing how multiband observations can reveal fundamental relationships in our understanding of the Universe.

Download or read book Wide Field Spectroscopy And The Distant Universe Proceedings Of The 35th Herstmonceux Conference written by S Maddox and published by World Scientific. This book was released on 1995-05-31 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies represent the most readily visible fabric of the cosmos. Their morphological types, luminosities and environmental surroundings contain valuable clues as to their origin and evolution. Locally, a strong correlation is seen between galaxy morphology and environmental location; this may have been molded at surprisingly modest redshifts. Spectroscopic and photometric studies of deep fields also suggest remarkably recent changes in the galaxy population. The associated growth of structure during the same interval can be tracked via X-ray studies of distant clusters of galaxies.Very recently, impressive observational facilities have been completed, each of which has extended the astronomers' dataset to look-back times where such evolutionary effects can be studied.This volume discusses surveys which share a common theme — the need for a large number of ground-based spectra. It focuses on the various approaches via a single theme concerned with the evolution of galaxies and their distribution. In the near future, impressive new observational facilities will be able to generate large statistical spectroscopic surveys, and the aim of this volume is to assess the scientific impact that ongoing and future spectroscopic surveys can make. Emphasis is placed on the role of non-optical and satellite facilities and the co-ordination of international efforts.

Download or read book New Worlds New Horizons in Astronomy and Astrophysics written by National Research Council and published by National Academies Press. This book was released on 2011-01-04 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.

Download or read book Star Formation in Merging Clusters of Galaxies written by Alison Seiler Mansheim and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis straddles two areas of cosmology, each of which are active, rich and plagued by controversy in their own right: merging clusters and the environmental dependence of galaxy evolution. While the greater context of this thesis is major cluster mergers, our individual subjects are galaxies, and we apply techniques traditionally used to study the differential evolution of galaxies with environment. Our first system (Chapter 2) is a cluster merger known as Musket Ball that is in a post-merging state. Our second system (Chapter 3), referred to as Cl J0910, is comprised of two clusters that have not yet merged. The order in which they are presented is intentional because, while it would have made more sense to study the pre-merger system first, our approach in Chapter 3 was shaped by what we learned by handling the significantly more difficult post-merger system. The body of this thesis is drawn from two papers: Mansheim et al. 2016a and Mansheim et al. 2016b, one on each system. Both projects benefited from exquisite data sets assembled as part of the Merging Cluster Collaboration (MC2), and Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey, allowing us to scrutinize the evolutionary states of galaxy populations in multiple lights. Multi-band optical and near-infrared imaging was available for both systems, allowing us to calculate photometric redshifts for completeness corrections, colors (red vs. blue) and stellar masses to view the ensemble properties of the populations in and around each merger. High-resolution spectroscopy was also available for both systems, allowing us to confirm cluster members by measuring spectroscopic redshifts, which are unparalleled in accuracy, and gauge star formation rates and histories by measuring the strengths of certain spectral features. We had the luxury of HST imaging for Musket Ball, allowing us to use galaxy morphology (late-type vs. early-type) as an additional diagnostic. For Cl J0910, 24 [mu]m imaging allowed us to defeat a most pernicious source of uncertainty (dusty starburst vs. quiescent). Details on the acquisition and reduction of multi-wavelength data for each system are found within each respective chapter. It is important to note that the research presented in Chapter 3 is based on a letter which had significant space restrictions, so much of the observational details are outsourced to papers written by ORELSE collaboration members. Below is a free-standing summary of each project, drawn from the abstracts of each paper. The Chapter 1 contains an introduction to the topic and motivation to fill a vacuum in knowledge using our hypothesis. Chapter 4, following the meat of the thesis in Chapters 2 and 3, gives closure and looks to the future. In Chapter 2, we investigate star formation in DLSCL J0916.2+2953, a dissociative merger of two clusters at z=0.53 that has progressed 1.1[superscript +1.3][subscript-0.4] Gyr since first pass-through. We attempt to reveal the effects a collision may have had on the evolution of the cluster galaxies by tracing their star formation history. We probe current and recent activity to identify a possible star formation event at the time of the merger using EW(H[delta]), EW[(OII)], and D[subscript n](4000) measured from the composite spectra of 64 cluster and 153 coeval field galaxies. We supplement Keck DEIMOS spectra with DLS and HST imaging to determine the color, stellar mass, and morphology of each galaxy and conduct a comprehensive study of the populations in this complex structure. Spectral results indicate the average cluster and cluster red sequence galaxies experienced no enhanced star formation relative to the surrounding field during the merger, ruling out a predominantly merger-quenched population. We find that the average blue galaxy in the North cluster is currently active and in the South cluster is currently post-starburst having undergone a recent star formation event. While the North activity could be latent or long-term merger effects, a young blue stellar population and irregular geometry suggest the cluster was still forming prior the collision. While the South activity coincides with the time of the merger, the blue early-type population could be a result of secular cluster processes. The evidence suggests that the dearth or surfeit of activity is indiscernible from normal cluster galaxy evolution. In Chapter 3, we examine the effects of an impending cluster merger on galaxies in the large scale structure (LSS) RX Cl J0910 at z =1.105. Using multi-wavelength data, including 102 spectral members drawn from the ORELSE survey and precise photometric redshifts, we calculate extinction-corrected star formation rates and map the specific star formation rate density of the LSS galaxies. These analyses along with an investigation of the color-magnitude properties of LSS galaxies indicate lower levels of star formation activity in the region between the merging clusters relative to the outskirts of the system. We suggest gravitational tidal forces due to the potential of merging halos may be the physical mechanisms responsible for the observed suppression of star formation in galaxies caught between the merging clusters.

Download or read book Dark Energy written by P. Ruiz-Lapuente and published by Cambridge University Press. This book was released on 2010-03-18 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complete and comprehensive introduction for physics graduate students just entering the field, and an authoritative reference for researchers.

Download or read book The IGM Galaxy Connection written by Jessica L. Rosenberg and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the meeting entitled, "The IGM/Galaxy Connection: The Distribution of Baryons at z = 0. " The meeting was held August 8 -10 at the National Center for Atmospheric Research (NCAR) located in Boulder, Colorado on the foothills of the Rocky Mountains (see conference photo). We organized this meeting because we felt it was time to address the link between galaxies and the intergalactic medium at low redshift. In this vein, we posed several questions to the conference participants: Where are the baryons in the local universe and in what phase do they reside? What signatures of galaxy evolution have been imprinted on the IGM? What percentage of intergalactic gas is left from the galaxy formation process? What does the distribution of baryons at z = 0 tell us about the early universe? The conference was an overwhelming success with lots of friendly interaction and discussion among the participants. At lunch we were treated to splendid views from the NCAR terrace and discussions rang ing from the importance of the LSR, GSR, and LGSR velocity frames to how long the desserts would last with 90 astronomers and the hot Boul der sun. From an inventory of the baryons, to the associations between galaxies and Lya absorbers, to the mechanisms by which galaxies obtain and lose gas, the conference covered many topics. The results of these endeavors are contained in these pages and eloquently summarized by Chris Impey.

Download or read book Large scale Structures in the Universe written by Waltraut Carola Seitter and published by . This book was released on 1988 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 International Workshop on Large Scale Structure in the Universe Potsdam 18 24 September 1994 written by Jan P. Mucket and published by World Scientific. This book was released on 1995 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dark Energy Survey The The Story Of A Cosmological Experiment written by Ofer Lahav and published by World Scientific. This book was released on 2020-08-19 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'The past cultures of astronomy and physics evolved their own distinct personalities. The book describes an important milestone in the history of the unification of the two fields and provides an excellent summary of the methods used to explore one of the greatest mysteries in physics today: dark energy.'Physics TodayThis book is about the Dark Energy Survey, a cosmological experiment designed to investigate the physical nature of dark energy by measuring its effect on the expansion history of the universe and on the growth of large-scale structure. The survey saw first light in 2012, after a decade of planning, and completed observations in 2019. The collaboration designed and built a 570-megapixel camera and installed it on the four-metre Blanco telescope at the Cerro Tololo Inter-American Observatory in the Chilean Andes. The survey data yielded a three-dimensional map of over 300 million galaxies and a catalogue of thousands of supernovae. Analysis of the early data has confirmed remarkably accurately the model of cold dark matter and a cosmological constant. The survey has also offered new insights into galaxies, supernovae, stellar evolution, solar system objects and the nature of gravitational wave events.A project of this scale required the long-term commitment of hundreds of scientists from institutions all over the world. The chapters in the first three sections of the book were either written by these scientists or based on interviews with them. These chapters explain, for a non-specialist reader, the science analysis involved. They also describe how the project was conceived, and chronicle some of the many and diverse challenges involved in advancing our understanding of the universe. The final section is trans-disciplinary, including inputs from a philosopher, an anthropologist, visual artists and a poet. Scientific collaborations are human endeavours and the book aims to convey a sense of the wider context within which science comes about.This book is addressed to scientists, decision makers, social scientists and engineers, as well as to anyone with an interest in contemporary cosmology and astrophysics.Related Link(s)

Download or read book Large Scale Structures in the Universe written by A. C. Fabian and published by . This book was released on 1987 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Early Universe with the VLT written by Jacqueline Bergeron and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second ESO workshop in aseries dedicated to science oppor tunities with the VLT. At the first workshop all areas of astronomical research were discussed. This second workshop is dedicated to research projects on the early Universe and has provided a forum for discussing strategies for studying faint distant objects in the optical and infrared spectral regions. This field is evolving very rapidly. There are several new surveys of galax ies and clusters of galaxies at intermediate redshift and quasars at very high redshift. Major advances in the morphological studies of distant galaxies, surveys of galaxies at high redshift and searches for primeval galaxies have been rendered possible by the new facilities provided by the Rubble Space Telescope and the Keck Telescope. Observational constraints on the evolution and formation of galaxies and large-scale structures as well as the cosmic chemical evolution were criti cally discussed with regard to theory and numerical simulations. In this context, the VLT first generation instrument capabilities were presented comprehensively and their use as cosmological tools discussed . The concluding remarks of the workshop focussed on the analysis of var ious possibilities for the VLT second generation instrumentation. Many of these topics were covered by invited reviews and talks, as well as some contributed talks. They are included in this volume together with the poster papers.

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.