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Probing The High Redshift Universe Using Fluctuations In The Cosmic Microwave And Infrared Backgrounds
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Book Synopsis Probing the High-redshift Universe Using Fluctuations in the Cosmic Microwave and Infrared Backgrounds by : Joseph Michael Smidt
Download or read book Probing the High-redshift Universe Using Fluctuations in the Cosmic Microwave and Infrared Backgrounds written by Joseph Michael Smidt and published by . This book was released on 2012 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Background (CIB) continues to be one of the best probes of physics at the early stages of the universe. If the CMB were a purely Gaussian field, all statistical information would be contained in the power spectrum or two-point correlation function. However, non-Gaussianities ensure that new physics may be extracted from higher n-point correlation functions including the bispectrum and trispectrum of the CMB. In this thesis discuss new estimators we have formulated to probe primordial non-Gaussianity in the bispectrum and trispectrum of CMB data and the constraints we have made using WMAP data while discussing implications for inflationary models. I discuss how these same methods may be used to probe CMB Lensing. Finally, I discuss how upcoming measurements of near and far-infrared CIB fluctuations may be used to constrain the redshift of reionization and clustering of various populations of galaxies. Some preliminary results involving CANDELS, Spitzer SDWFS, CIBER and Herschel datasets is presented.
Book Synopsis Illuminating the Universe by : Stephen John Osborne
Download or read book Illuminating the Universe written by Stephen John Osborne and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The cosmic microwave background (CMB) provides a backlight that allows us to probe structure out to the last scattering surface. We exploit observations of the sky at microwave and sub-mm wavelengths to measure properties of galaxies and galaxy clusters, as well as to search for possible pre-inflationary signals. In Chapters 2--4 we measure the correlation between the dark matter distribution and the microwave and sub-mm emission from galaxies to probe the connection between dark and luminous matter at redshifts ~1-3. CMB photons are gravitationally deflected by dark matter overdensities, with the majority of the ~3 arcminute RMS deflection occurring between redshift 2 and 3. The dark matter structures that lens the CMB are traced by dusty star-forming galaxies that emit strongly in the infrared, and have a redshift distribution that peaks between redshift 1 and 3. We use observations of the CMB from the Planck satellite to reconstruct the deflection angles with statistical estimators, and we correlate the deflections with observations of the infrared background light at 100-850 GHz. We find that the two signals are strongly correlated, with a correlation coefficient of approximately 0.8, and we use the measured cross spectrum to estimate the minimum mass scale at which dark matter halos host a CIB source, as well as the star formation rate density in three redshift bins between redshift 1 and 7. In Chapter 5 we use the Doppler shift of CMB light scattered by moving galaxy clusters, known as the kinetic Sunyaev-Zeldovich (kSZ) effect, to put a limit on the large-scale velocity distribution of a sample of galaxy clusters observed in WMAP CMB data. On 100 Mpc scales cluster velocities relative to the CMB are expected to be small, originating from gravitational instabilities. Larger motions could be generated by pre-inflationary inhomogeneities that leave a "tilt" across our horizon, resulting in a uniform matter flow across the horizon. The kSZ effect is sensitive to such a flow, and we use it to constrain the radial and dipole velocity of a sample of 736 clusters with mean redshift 0.12, finding no evidence for either. In Chapters 6 and 7 we search for a possible pre-inflationary signal in CMB data. Models of inflation suggest that our current patch of the universe could have been created as a nucleation bubble from a phase of false vacuum eternal inflation. If additional bubbles are produced, then it is possible that one of them intersected our past lightcone at the time of decoupling, imprinting a disk-shaped signal in the CMB. We have searched for this signal in the WMAP data using optimal algorithms that evaluate the exact posterior likelihood in an efficient and computationally fast way. We find no evidence for the signal, and place limits on the curvature perturbation generated by a collision intersecting the last scattering surface.
Book Synopsis The Intrinsic Bispectrum of the Cosmic Microwave Background by : Guido Walter Pettinari
Download or read book The Intrinsic Bispectrum of the Cosmic Microwave Background written by Guido Walter Pettinari and published by Springer. This book was released on 2015-09-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nominated as an outstanding thesis by Professor Robert Crittenden of the Institute of Cosmology and Gravitation in Portsmouth, and winner of the Michael Penston Prize for 2014 given by the Royal Astronomical Society for the best doctoral thesis in Astronomy or Astrophysics, this work aims to shed light on one of the most important probes of the early Universe: the bispectrum of the cosmic microwave background. The CMB bispectrum is a potential window on exciting new physics, as it is sensitive to the non-Gaussian features in the primordial fluctuations, the same fluctuations that evolved into today’s planets, stars and galaxies. However, this invaluable information is potentially screened, as not all of the observed non-Gaussianity is of primordial origin. Indeed, a bispectrum arises even for perfectly Gaussian initial conditions due to non-linear dynamics, such as CMB photons scattering off free electrons and propagating in an inhomogeneous Universe. Dr. Pettinari introduces the reader to this intrinsic bispectrum in a pedagogic way, building up from the standard model of cosmology and from cosmological perturbation theory, the tool cosmologists use to unravel the history of the cosmos. In doing so, he introduces SONG, a new and efficient code for solving the second-order Einstein and Boltzmann equations. Next, he moves on to answer the crucial question: is the intrinsic bispectrum going to screen the primordial signal in the CMB? Using SONG, he computes the intrinsic bispectrum and shows how its contamination leads to a small bias in the estimates of primordial non-Gaussianity, a great news for the prospect of using CMB data to probe primordial non-Gaussianity.
Book Synopsis The Cosmic Infrared Background ExpeRiments by : Chi Hanh Nguyen
Download or read book The Cosmic Infrared Background ExpeRiments written by Chi Hanh Nguyen and published by . This book was released on 2021 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The ensemble emission from all sources outside of the Milky Way is known as the extragalactic background light (EBL). At optical and near-infrared (NIR) wavelengths, the EBL is primarily stellar emission tracing back to the Epoch of Reionization (EOR) at redshifts z > 6 when the first luminous structures formed. Given the large uncertainties in our understanding of the EOR, measurements of the EBL provide an important probe of the galaxies that were responsible for reionization. Direct observations of the EBL are challenging due to contamination from bright local foregrounds. In recent years, intensity mapping has emerged as a successful technique in which EBL fluctuations are measured on large angular scales where the known foreground contributions are minimal or well-modeled. To isolate the signals from EOR structures, intensity mapping can be applied to optical and NIR data to probe rest-frame UV emission in galaxies at z > 6. Multiple intensity mapping studies including the first Cosmic Infrared Background ExpeRiment (CIBER-1) have found that the optical/NIR EBL intensity and its large-scale fluctuations exceed predictions from galaxy models. The excess is above EOR level and also persists at wavelengths
Book Synopsis Examining the Big Bang and Diffuse Background Radiations by : Menas Kafatos
Download or read book Examining the Big Bang and Diffuse Background Radiations written by Menas Kafatos and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU Symposium No. 168, Examining the Big Bang and Diffuse Background Radiations, took place on August 23-26, 1994 at the XXIInd IAU General Assembly in the Hague, Netherlands. The meeting attracted a large number - over 250 - of astronomers, reflecting the strong interest engendered by the great advances in cosmology made in recent years. There is still a multitude of unresolved problems in modern cosmology and the symposium offered a wonderful occasion to examine them objectively, at a place where many leading workers in related fields gathered together. After the introduction by IAU President L. Woltjer and the historical background by Vice Present Virginia Trimble, the volume begins with reviews of the cosmic microwave radiation from COBE (Cosmic Background Explorer). Reviews of recent observations then extend from radio to infrared, visible light, ultraviolet, X-rays and gamma-rays. It is followed by theoretical models for the Big Bang and Inflation, and alternative views to the Big Bang. Following a discourse on Probes and Future Tests, the meeting ended with a Panel Discussion on `Major Unsolved Problems of Cosmology'. Some forty-four contributed papers - both oral and poster reports - are included after the invited talks and panel discussions.
Book Synopsis Understanding the Epoch of Cosmic Reionization by : Andrei Mesinger
Download or read book Understanding the Epoch of Cosmic Reionization written by Andrei Mesinger and published by Springer. This book was released on 2015-11-28 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dawn of the first stars, galaxies and black holes signaled a fundamental milestone in our Universe’s evolution: the Epoch of Reionization. The light from these galactic ancestors began spreading out, ionizing virtually every atom in existence. Our Universe transitioned from darkness to light, from cold to hot, from simple and boring to the wondrous cosmic zoo we see around us today. Despite its importance, observations of reionization have been few, and their interpretation has been highly controversial. Fortunately, this is rapidly changing. We will soon enter the "Big Data” era of this mysterious epoch, driven by an upcoming wave of observations with state-of-the-art telescopes as well as new sophisticated analysis tools. The aim of this volume is to summarize the current status and future outlook of the reionization field. We bring together leading experts in many sub-disciplines, highlighting the measurements that will illuminate our understanding of reionization and the cosmic dawn: (i) 21cm interferometry; (ii) high-redshift quasar spectra; (iii) high-redshift galaxy surveys; (iv) primary and secondary anisotropies of the Cosmic Microwave Background; (v) high-resolution studies of the metal content of early galaxies. We seek a roadmap to interpreting the wealth of upcoming observations. What is the best use of limited observational resources? How do we develop theoretical tools tailored for each observation? Ultimately, what will we learn about the epoch of reionization and our galactic ancestors?
Book Synopsis Cross-correlations in the Dark Energy Survey by : Pauline Eva Vielzeuf
Download or read book Cross-correlations in the Dark Energy Survey written by Pauline Eva Vielzeuf and published by . This book was released on 2018 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past decades, we have been the witnesses of unprecedented advancements in the understanding of our universe dynamics and evolution. Indeed, together with the theory General Relativity (GR) by Albert Einstein at the beginning of the 1900's, the improvement of observational tools have led to the establishment of the standard model of cosmology the so-called ∧-cold-Dark-Matter model (∧CDM) that is so far the simplest model that describes best our universe considering observations. However, this standard model suffers from caveats, more specifically the presence in the theory of two dark components, Dark Energy and Dark Matter. Understanding the mystery behind these two components have become the leading objective of observational cosmology today, and of current experiments, as it is the case of the Dark Energy Survey (DES), that will after 5 years of observations image about 300 million galaxies with an unprecedented depth covering one eighth of the sky (5000 sq. deg.). This thesis is based on the analysis of the first year of observation of DES (DESY1) and more in particular on the use of cross-correlation techniques in cosmological analyses. Here, we expose two of different possible use of cross-correlation. Namely, we first show how cross-correlation techniques has been employed as a tool to infer redshift distribution of objects using the socalled clustering-redshift methodologies. And moreover how for the first time this techniques have entered in the cosmological analyses to correct the mean of the redshift distributions of the DESY1 galaxy catalog with shapes (the weak lensing sample) inferred by typical photometric techniques. We explain how using simulation we have evaluated systematics errors induced by our overall methodology and present the full methodology employed for redshift distribution determination of the DESY1 Weak lensing sample. In a second time, we expose how we have been using cross-correlations as a probe of ∧CDM cosmology using in one hand cross-correlation between cosmic voids identified in the DESY1 catalogs and the lensing map from the Planck satellite and on the other hand simulated ∧CDM cosmology. More specifically, recent results have suggested an excess signal in the observed void catalogs imprint in the Cosmic Microwave Background temperature maps with respect to simulated ∧CDM cosmology, we reiterate the procedure using this time the lensing maps of the CMB. After optimizing our void catalogs in simulation, looking for population of voids responsible for the more significant detection,we could detect the imprint of DESY1 cosmic voids with a significance of ̃ 7 – 12ơ with a discrepancy of ̃ 3 – 9ơ with respect to ∧CDM simulations.
Book Synopsis The Cosmic Microwave Background by : C.H. Lineweaver
Download or read book The Cosmic Microwave Background written by C.H. Lineweaver and published by Springer. This book was released on 2011-09-20 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute on the Cosmological Background Radiation, Strasbourg, France, May 27-June 7, 1996
Book Synopsis Fluctuations in Radiation Backgrounds at High Redshift and the First Stars by : Lauren Nicole Holzbauer
Download or read book Fluctuations in Radiation Backgrounds at High Redshift and the First Stars written by Lauren Nicole Holzbauer and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first stars to light up our universe are as yet unseen, but there have been many attempts to elucidate their properties. The characteristics of these stars (`Population/Pop III' stars) that we do know lie mostly within theory; they formed out of metal-free hydrogen and helium gas contained in dark matter minihalos at redshifts z ~ 20-30. The extent to which Pop III star formation reached into later times is unknown. Current and near future instruments are incapable of resolving individual Pop III stars. Consequently, astronomers must devise creative means with which to indirectly predict and measure and their properties. In this thesis, we will investigate a few of those means. We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman- & alpha; radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons (11.5-13.6 eV) are of particular interest because they dissociate molecular hydrogen, the primary coolant in the first minihalos that is necessary for star formation. By using a variation of the `halo model', which describes the spatial distribution and clustering of halos, we can efficiently generate power spectra for these backgrounds. Spatial fluctuations in the LW and (indirectly) the Lyman-[alpha] BG can tell us about the transition from primordial star formation to a more metal-enriched mode that marks the beginning of the second generation of stars in our Universe. The Near Infrared Background (NIRB) has for some time been considered a potential tool with which to indirectly observe the first stars. Ultraviolet (UV) emission from these stars is redshifted into the NIR band, making the NIRB amenable for hunting Pop III stellar signatures. There have been several measurements of the NIRB and subsequent theoretical studies attempting to explain them in recent years. Though controversial, residual levels of the mean NIRB intensity and anisotropies have been detected after subtracting all known foreground stars and galaxies. Pop III stars have been the leading candidates thought responsible for this observed NIRB excess. We model the Pop III stellar contribution to the NIRB mean intensity and fluctuations and generate observationally motivated values of the star formation (SF) efficiency using high redshift measurements of the UV luminosity density with UDF09, UDF12, and WMAP-9 data. This allows us to characterize the properties of a Pop III stellar population that are required to produce the measured excess. Finally, we propose a new method for detecting primordial metal-free and very metal-poor stellar populations by cross-correlating fluctuations in the intensity of Lyman- & alpha; and He II [lambda]1640 emission sourced from high redshifts. Pop III stars are expected to be more massive and more compact than later generations of stars. This results in a much harder ionizing spectrum. A large portion of the ionizing photons have energies with hv> 54.4 eV that carve out substantial patches of doubly ionized helium, He III. These photoionized regions then begin to shine brightly in He II recombination emission. Due to the lack of heavy elements in these regions, Pop III stars must rely on hydrogen and helium for cooling, enhancing both the Lyman-[alpha] and He II emission lines. In this regard, Pop III stars can be characterized as `dual emitters, ' i.e. producers of both Lyman-[alpha] and He II emission signatures. Though Lyman-[alpha] emission is characteristic of both metal-free and metal-enriched stars, He II emission appears to be unique to extremely metal poor stars and metal-free stars, making it a very strong signature of the first stars. Detecting Lyman-[alpha] + He II dual emission in individual galaxies at high redshift is difficult and so far rare. The astrophysical engines powering the few Lyman-[alpha] + He II dual emitters that have been discovered have still not been clearly identified. Alternatively, we may be able to map fluctuations in the total intensity of the Lyman-[alpha] and He II [lambda]1640 lines, which will allow us to indirectly assess sources that are below typical luminosity thresholds of deep surveys. Cross-correlating these lines can provide us with a useful new tool for inferring properties of the first stars, since the two lines together allow us to better isolate the redshift of source emission and the presence of He II [lambda]1640 emission is extremely sensitive to stellar metallicity.
Book Synopsis The Cosmological Background Radiation by : Marc Lachièze-Rey
Download or read book The Cosmological Background Radiation written by Marc Lachièze-Rey and published by Cambridge University Press. This book was released on 1999-06-10 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to the physics, astrophysics and cosmology of the cosmic microwave background radiation. Adopting the Standard Big Bang model of the universe, the authors cover topics including the origin of the background, intrinsic fluctuations, and the universe and background radiation after recombination. Finally they present measurement of the radiation and its anisotropies, along with a review of the current status of results and experiments. The authors assume the reader has a basic understanding of the central concepts of general relativity, but they avoid complex mathematical proofs and manipulations, preferring instead to concentrate on the information needed by hands-on cosmologists and astrophysicists. In this first edition in the English language, the authors have completely revised the text of the French edition. The level is ideally suited to final-year undergraduates in physics or astronomy.
Book Synopsis 3K: The Cosmic Microwave Background Radiation by : R. B. Partridge
Download or read book 3K: The Cosmic Microwave Background Radiation written by R. B. Partridge and published by Cambridge University Press. This book was released on 1995-07-13 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review covering all aspects of the study of the cosmic background radiation remnant of the hot Big Bang origin of the Universe.
Book Synopsis Background Microwave Radiation and Intracluster Cosmology by : Società italiana di fisica
Download or read book Background Microwave Radiation and Intracluster Cosmology written by Società italiana di fisica and published by IOS Press. This book was released on 2005 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focuses on the Sunyaev-Zeldovich (S-Z) effect, and related topics in cluster and CMB research. The pedagogical reviews and technical seminars included in this volume represent important topics in S-Z work and in the astrophysics of clusters. This work touches upon various aspects of the S-Z effect and its use as a cluster and cosmological probe.
Book Synopsis Looking Deep in the Southern Sky by : Raffaella Morganti
Download or read book Looking Deep in the Southern Sky written by Raffaella Morganti and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The idea of a joint ESO / Australia meeting on the large number of exciting new facilities that are, or will soon be, available tihne southern hemisphere arose quite naturally. In the optical and the near-infrared, the Very Large Telescope (VLT) will soon be operational. In the radio, the Australia Telescope Com pact Array is going to be upgraded to higher frequencies (20 and 100 GHz), together with an improvement in very long baseline interferometry (VLBI) facil ities. Other major facilities, such as the Large Millimetre Array and the lkT are being planned. Moreover, new deep surveys are underway in the southern hemi sphere: the southern Hubble Deep Field, the ESO Imaging Survey (BIS), pan oramic deep surveys with the UK Schmidt telescope, and the Anglo-Australian Telescope (AAT) 2dF galaxy/QSO redshift survey in the optical; and the Parkes multibeam HI survey and Molonglo Observatory Synthesis Telescope (MOST) Wide Field continuum survey at radio wavelengths. With all these new facilities, important progress will be made regarding important issues such as the large scale structure of the universe, the very early universe and the associated first epoch of galaxy formation. The generation of large databases, and the oppor tunity for sensitive follow-up observations in complementary wavebands, mean that coordinated radio, infrared and optical projects in the southern hemisphere are likely to become increasingly attractive and important.
Book Synopsis Galaxies and the Cosmic Frontier by : William Howard Waller
Download or read book Galaxies and the Cosmic Frontier written by William Howard Waller and published by Harvard University Press. This book was released on 2003 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Featuring the latest observations and most compelling theories, this book provides a firm foundation for exploring the more speculative reaches of our current understanding."--BOOK JACKET.
Book Synopsis The Physics of the Cosmic Microwave Background by : Pavel D. Naselsky
Download or read book The Physics of the Cosmic Microwave Background written by Pavel D. Naselsky and published by Cambridge University Press. This book was released on 2011-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectacular observational breakthroughs, particularly by the WMAP satellite, have led to a new epoch of CMB science long after its original discovery. Taking a physical approach, the authors of this volume probe the problem of the 'darkness' of the Universe: the origin and evolution of dark energy and matter in the cosmos. Starting with the observational background of modern cosmology, they provide an accessible review of this fascinating yet complex subject. Topics discussed include the kinetics of the electromagnetic radiation in the Universe, the ionization history of cosmic plamas, the origin of primordial perturbations in light of the inflation paradigm, and the formation of anisotropy and polarization of the CMB. This fascinating review will be valuable to advanced students and researchers in cosmology.
Book Synopsis The Cosmic Microwave Background by : Ruth Durrer
Download or read book The Cosmic Microwave Background written by Ruth Durrer and published by Cambridge University Press. This book was released on 2020-12-17 with total page 519 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate textbook describes the physics of the Cosmic Microwave Background, arguably the most important topic in modern cosmology.
Book Synopsis NASA's Beyond Einstein Program by : National Research Council
Download or read book NASA's Beyond Einstein Program written by National Research Council and published by National Academies Press. This book was released on 2008-01-19 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Beyond Einstein science" is a term that applies to a set of new scientific challenges at the intersection of physics and astrophysics. Observations of the cosmos now have the potential to extend our basic physical laws beyond where 20th-century research left them. Such observations can provide stringent new tests of Einstein's general theory of relativity, indicate how to extend the Standard Model of elementary-particle physics, and-if direct measurements of gravitational waves were to be made-give astrophysics an entirely new way of observing the universe. In 2003, NASA, working with the astronomy and astrophysics communities, prepared a research roadmap entitled Beyond Einstein: From the Big Bang to Black Holes. This roadmap proposed that NASA undertake space missions in five areas in order to study dark energy, black holes, gravitational radiation, and the inflation of the early universe, to test Einstein's theory of gravitation. This study assesses the five proposed Beyond Einstein mission areas to determine potential scientific impact and technical readiness. Each mission is explored in great detail to aid decisions by NASA regarding both the ordering of the remaining missions and the investment strategy for future technology development within the Beyond Einstein Program.
