Download or read book The Atacama Cosmology Telescope written by Ryan P. Fisher and published by . This book was released on 2009 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book From Data to Maps with the Atacama Cosmology Telescope written by Rolando Dünner Planella and published by . This book was released on 2009 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring the Universe with the Atacama Cosmology Telescope written by Marius Lungu and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past twenty-five years, observations of the Cosmic Microwave Background (CMB) temperature fluctuations have served as an important tool for answering some of the most fundamental questions of modern cosmology: how did the universe begin, what is it made of, and how did it evolve? More recently, measurements of the faint polarization signatures of the CMB have offered a complementary means of probing these questions, helping to shed light on the mysteries of cosmic inflation, relic neutrinos, and the nature of dark energy. A second-generation receiver for the Atacama Cosmology Telescope (ACT), the Atacama Cosmology Telescope Polarimeter (ACTPol), was designed and built to take advantage of both these cosmic signals by measuring the CMB to high precision in both temperature and polarization. The receiver features three independent sets of cryogenically cooled optics coupled to transition-edge sensor (TES) based polarimeter arrays via monolithic silicon feedhorn stacks. The three detector arrays, two operating at 149 GHz and one operating at both 97 and 149 GHz, contain over 1000 detectors each and are continuously cooled to a temperature near 100 mK by a custom-designed dilution refrigerator insert. Using ACT's six meter diameter primary mirror and diffraction limited optics, ACTPol is able to make high-fidelity measurements of the CMB at small angular scales (l ~ 9000), providing an excellent complement to Planck. The design and operation of the instrument are discussed in detail, and results from the first two years of observations are presented. The data are broadly consistent with /\CDM and help improve constraints on model extensions when combined with temperature measurements from Planck.
Download or read book Development of Technologies for the Atacama Cosmology Telescope and Next Generation Cosmic Microwave Background Instruments written by Jonathan Ward and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A primary goal of modern cosmology is to obtain cosmological information and parameters from high-sensitivity measurements of the temperature and polarization of the Cosmic Microwave Background (CMB) radiation. These measurements will allow cosmologists to probe the many predictions made by the inflationary model of the Universe. To continue expanding the limits of CMB science, experimentalists need to develop novel technologies that will continue to improve our ability to observe the microwave sky. Paired with state of the art data analysis techniques, our understanding of the Universe will continue to grow now and for decades to come.The Atacama Cosmology Telescope (ACT) is a 6-meter diameter telescope located in the Andes Mountains of Northern Chile. Deployment of the Advanced ACTPol (AdvACT) receiver has vastly improved the capabilities of ACT. Next-generation detector arrays operating at 20, 40, 90, 150, and 240 GHz will provide the frequency coverage and detector count necessary to improve measurements of a wide range of cosmological parameters. Continuously rotating half-wave plates (HWPs) modulate the incoming polarized signal, resulting in a drastic suppression of the atmospheric 1/f noise that contaminates the ACT data at large angular scales. Finally, hardware and software upgrades to previous-generation ACTPol infrastructure have further improved the AdvACT instrument on the fronts of cryogenic performance, housekeeping data acquisition, assembly procedure, and site reliability. The design and deployment of AdvACT instrumentation is discussed in detail from Chapters 2-4, highlighting the key design changes and improvements over the ACTPol experiment. In addition to the instrumentation advances discussed above, data analysis and numerical modeling techniques provide the framework needed to extract the most information from the data gathered by the AdvACT experiment. Key efforts focused towards processing HWP data allows ACT to probe the inflationary gravitational wave signal that may lie in the low-frequency regime of the ACT data. Furthermore, simulations help predict the effects of various systematics on the raw data give a better understanding of what calibration strategies are needed to mitigate systematic effects. The software developed to accomplish these tasks is discussed in Chapters 5-6, along with the results obtained from the data when the code is implemented in the analysis pipeline. The technologies, instrumentation, and analysis techniques outlined in this paper and employed by the AdvACT experiment will continue to push ACT to the forefront of experimental cosmology research while also providing a template for future experimental efforts.
Download or read book Detectors for the Atacama Cosmology Telescope written by Tobias Andrew Marriage and published by . This book was released on 2006 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Atacama Cosmology Telescope (ACT) will make measurements of the brightness temperature anisotropy in the Cosmic Microwave Background (CMB) on degree to arcminute angular scales. The ACT observing site is located 5200 m near the top of Cerro Toco in the Atacama Desert of northern Chile. This thesis presents research on the detectors which capture the image of the CMB formed at ACT's focal plane. In the first chapter, the primary brightness temperature fluctuations in the Cosmic Microwave Background are reviewed. In Chapter 2, a calculation shows how the CMB brightness is translated by ACT to an input power to the detectors. Chapter 3 describes the ACT detectors in detail and presents the response and sensitivity of the detectors to the input power computed in Chapter 2. Chapter 4 describes the detector fabrication at NASA Goddard Space Flight Center. Chapter 5 summarizes experiments which characterize the ACT detector performance.
Download or read book The Atacama Cosmology Telescope written by Gustavo Morales Correa and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sidelobes and Spillover in the Atacama Cosmology Telescope written by Patricio Andrés Gallardo Matamala and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Atacama Cosmology Telescope written by and published by . This book was released on 2013 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Galaxy Cluster Cosmology with the Atacama Cosmology Telescope written by Matthew Hasselfield and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Atacama Cosmology Telescope written by and published by . This book was released on 2011 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present constraints on cosmological parameters based on a sample of Sunyaev-Zeldovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives? = 0.851 ± 0.115 and w = -1.14 ± 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find?8 = 0.821 ± 0.044 and w = -1.05 ± 0.20. These results are consistent with constraints from WMAP 7 plus baryon acoustic oscillations plus type Ia supernoava which give?8 = 0.802 ± 0.038 and w = -0.98 ± 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.
Download or read book Detector Development and Polarization Analyses for the Atacama Cosmology Telescope written by Brian James Koopman and published by . This book was released on 2018 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are currently in an era of precision cosmology. Study of the Cosmic Microwave Background (CMB) has been central to our understanding of the universe ever since its discovery in 1965. Recent results from the Planck satellite have provided the best constraints on the 6-parameter $\Lambda\mathrm{CDM}$ model, the "standard model'' of cosmology. In order to improve these constraints we must further the development of the technologies used to measure the CMB as well as our understanding of their associated systematics. The Atacama Cosmology Telescope Polarimeter (ACTPol) and its successor instrument, known as Advanced ACTPol (AdvACT), are polarization sensitive upgrades to the Atacama Cosmology Telescope (ACT). ACT is an off-axis Gregorian telescope with a 6m primary reflector and a 2m secondary reflector. The ACTPol and AdvACT instruments utilize kilo-pixel scale arrays of superconducting transition edge sensor (TES) bolometers to measure the CMB anisotropies at frequencies ranging from 27-220 GHz. The increased spectral coverage of AdvACT will enable a wide range of CMB science, such as improving constraints on dark energy, the sum of the neutrino masses, and the existence of primordial gravitational waves. Precise polarization calibration can also enable improved constraints on cosmic polarization rotation. In this thesis we present an overview of the AdvACT instrument before detailing the development of the AdvACT TES device geometries, which are tuned specifically for each of AdvACT's five frequency bands (27, 39, 90, 150, and 220 GHz). Each detector couples to a single linear polarization. The angle of this coupling projected onto the sky is a critical calibration step in making maps of the CMB polarization. Any offset in this calibration angle can introduce a spurious B-mode polarization signal, resulting in non-zero EB and TB cross-correlation power spectra. ACTPol uses a unique optical modeling based approach to this calibration. We present this procedure, as well as a method for directly measuring the relative angles of the detectors by use of a rapidly rotating polarizer. We also present maps of the polarized source Tau A, from the first three seasons of ACTPol at 90 and 150 GHz and discuss how these maps are affected by the polarization calibration. Finally, we discuss the telescope control, computer systems, and remote observations team which keep the telescope running, and briefly conclude with a summary that motivates improving calibration techniques for future CMB experiments.
Download or read book The Atacama Cosmology Telescope written by Cristóbal Javier Sifón Andalaft and published by . This book was released on 2012 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Toward a Mass limited Catalog of Galaxy Clusters from the Atacama Cosmology Telescope written by Adam Douglas Hincks and published by . This book was released on 2009 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of the Sunyaev Zel dovich Galaxy Clusters from the Atacama Cosmology Telescope written by David M. Holtz and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Towards Next Generation Millimeter Wave Cosmology from the Atacama written by Zequn Li and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We expect both exciting new insights and analysis challenges from ground-based CMB surveys in the next decade, such as from the existing Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT), as well as from the upcoming Simons Observatory and CMB-S4.In this thesis, we demonstrate the utility of cross-correlating data from a large aperture instrument (ACT) with data from the Atacama B-mode Search (ABS), a small aperture instrument equipped with a half-wave plate, to target the polarization at large scales from the ground. This strategy is able to significantly suppress atmospheric contamination of the resulting power spectrum, and we expect to employ it in upcoming surveys. We then implement a complete Planck satellite analysis pipeline that reproduces both the intermediary and cosmological results of the PR3 data release. This effort is required for current and future joint analysis efforts of the Planck data with new, large-sky-fraction observations such as from ACT and Simons Observatory.We also present new simulated catalogs and maps of radio galaxies, which are consistent with the latest radio data (unlike pre-existing works). These radio sources present a challenge for a variety of cosmological analyses in the millimeter. These maps are also correlated with the large-scale structure through the Websky simulations. Finally, we provide new constraints on the interaction cross section between dark matter and baryons in the early Universe, by combining ACT DR4 data with Planck PR3. We show that the addition of small-scale data from ACT nearly halves the allowed parameter space of dark matter-baryon interaction models, compared to previous work using Planck alone.
Download or read book Our Universe written by Jo Dunkley and published by Belknap Press. This book was released on 2019-04-08 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: A BBC Sky at Night Best Astronomy and Space Book of the Year “[A] luminous guide to the cosmos...Jo Dunkley swoops from Earth to the observable limits, then explores stellar life cycles, dark matter, cosmic evolution and the soup-to-nuts history of the Universe.” —Nature “A grand tour of space and time, from our nearest planetary neighbors to the edge of the observable Universe...If you feel like refreshing your background knowledge...this little gem certainly won’t disappoint.” —Govert Schilling, BBC Sky at Night Most of us have heard of black holes and supernovas, galaxies and the Big Bang. But few understand more than the bare facts about the universe we call home. What is really out there? How did it all begin? Where are we going? Jo Dunkley begins in Earth’s neighborhood, explaining the nature of the Solar System, the stars in our night sky, and the Milky Way. She traces the evolution of the universe from the Big Bang fourteen billion years ago, past the birth of the Sun and our planets, to today and beyond. She then explains cutting-edge debates about such perplexing phenomena as the accelerating expansion of the universe and the possibility that our universe is only one of many. Our Universe conveys with authority and grace the thrill of scientific discovery and a contagious enthusiasm for the endless wonders of space-time.
Download or read book Astronomical Observatories in Chile written by Source Wikipedia and published by University-Press.org. This book was released on 2013-09 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 32. Chapters: Atacama Cosmology Telescope, Atacama Large Millimeter Array, Cerro Armazones Observatory, Cerro Chajnantor Atacama Telescope, Cerro Pachon, Cerro Tololo Inter-American Observatory, Cosmic Background Imager, European Extremely Large Telescope, European Southern Observatory, Gemini Observatory, Las Campanas Observatory, La Silla Observatory, Llano de Chajnantor Observatory, Magellan Planet Search Program, MPG/ESO telescope, NANTEN2 Observatory, National Astronomical Observatory (Chile), National Optical Astronomy Observatory, Overwhelmingly Large Telescope, Paranal Observatory, QUIET, Slooh, University of Tokyo Atacama Observatory, University of Toronto Southern Observatory, Victor M. Blanco Telescope.
