PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute

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ACKNOWLEDGMENTS thesis is dedicated, I could not have completed the thesis. My wife Monalisa played a very vital role in my pursuing the Ph.D. degree. She understands perfectly how life is for a research scholar and makes things easier for me. Her constant support and inspiration elevated the level of my work. When it comes to my friends, all the worries, frustrations and difficulties were smoothed over by their presence. My seniors Mama, Kaka, Subhada, JD had given me every possible advice to overcome many hurdles. Sanjoyda (a.k.a Harr), who is like my elder brother, taught me physics in the simplest way I could imagine. Being a friend from my undergraduate days at Jadavpur, Niyogi has always been a companion in my studies as well as in many aspects of life. I must mention Pandu, with whom I shared a passion to explore the new features of Linux. During my Master’s and Ph.D. here at HRI, troubled times were always diluted by the indoor and outdoor games with Pandu, Sanjoyda and Niyogi. As a fellow post-B.Sc. student, Satya was an integral part of my journey in the field of research. Sharing jokes and fun with Bhuru was an inseparable part during my stay at HRI. I always enjoyed the sleepless nights at HRI with Sanjoyda, JD, Mama, Shamikda, Kaka, Niyogi, Pandu, Satya, Bhuru, Hochi, Ramva, Manoj, Jonthu, Rana and many more, discussing every possible topic on Earth. I salute the simple cup of tea at the HRI guest house which was the abstract source of energy for the research here. Sumitda from Jadavpur has been appreciative as well as critical of my efforts, and had also provided me with inspiration when I needed it. So, in a word, I have been privileged to have good friends, and I think my thesis has been enriched by their presence. x
Abstract Currently, inflation is the most promising paradigm to describe the origin of the perturbations in the early universe. Most models of inflation permit a sufficiently long epoch of slow roll inflation, which, in turn, leads to a featureless, nearly scale invariant, power law, primordial scalar spectrum. Such a spectrum, along with the assumption of a spatially flat, concordant ΛCDM [i.e. involving the cosmological constant Λ and Cold Dark Matter CDM)] background cosmological model, provides a good fit to the recent observations of the anisotropies in the Cosmic Microwave Background (CMB) by missions such as the Wilkinson Microwave Anisotropy Probe (WMAP). Even though, as a broad paradigm, inflation can be termed as a success, it would be fair to say that we are still some distance away from converging upon a specific model or even a class of models. There exist a wide variety of inflationary models that remain consistent with the data. While a nearly scale invariant, power law, scalar spectrum fits the observations of the anisotropies in the CMB quite well, there exist a few data points at the lower multipoles, which lie outside the cosmic variance associated with the conventional power law primordial spectrum. Statistically, a few outliers in a thousand or so data points are always expected. However, these outliers can be handy from the phenomenological perspective of attempting to constrain the models from the data, since only a more restricted class of inflationary models can be expected to provide an improved fit to these outliers. Therefore, it is a worthwhile exercise to explore models that lead to certain deviations from the standard power law, inflationary perturbation spectrum, and also provide a better fit to the data. Over the last few years, it has been recognized that primordial non-Gaussianity can act as a powerful probe to help us discriminate further between the various inflationary models. For instance, it is known that slow roll inflation driven by the canonical scalar fields leads only to a small amount of non-Gaussianity. But, recent analyses of the WMAP data seem to suggest that primordial non-Gaussianity may possibly be large. Ongoing missions such as Planck are expected to determine the extent of non-Gaussianity in the xi
Page 1: Primordial features and non-Gaussia
Page 5: Declaration This thesis is a presen
Page 9: Acknowledgments According to a popu
Page 13 and 14: ABSTRACT tensors prove to be small
Page 15 and 16: ABSTRACT the best fit values arrive
Page 17 and 18: Contents 1 Introduction 1 1.1 The c
Page 19: CONTENTS 6 Effects of primordial fe
Page 23 and 24: List of Figures 1.1 A schematic tim
Page 25 and 26: Chapter 1 Introduction At a first g
Page 27 and 28: 2.725K. It is also found to be high
Page 29 and 30: 1.1. THE CONCORDANT, BACKGROUND COS
Page 31 and 32: 1.2. THE INFLATIONARY PARADIGM 1.2
Page 33 and 34: 1.2. THE INFLATIONARY PARADIGM log
Page 35 and 36: 1.2. THE INFLATIONARY PARADIGM wher
Page 37 and 38: 1.2. THE INFLATIONARY PARADIGM wher
Page 39 and 40: 1.2. THE INFLATIONARY PARADIGM The
Page 41 and 42: 1.2. THE INFLATIONARY PARADIGM yet
Page 43 and 44: 1.3. THE GENERATION AND IMPRINTS OF
Page 45 and 46: 1.5. THE FORMATION OF THE LARGE SCA
Page 47 and 48: 1.7. NOTATIONS AND CONVENTIONS resu
Page 49 and 50: Chapter 2 Generation of localized f
Page 51 and 52: 2.1. THE INFLATIONARY MODELS OF INT
Page 53 and 54: 2.2. METHODOLOGY, DATASETS, AND PRI
Page 55 and 56: 2.2. METHODOLOGY, DATASETS, AND PRI
Page 57 and 58: 2.3. BOUNDS ON THE PARAMETERS 2.3 B
Page 59 and 60: 2.3. BOUNDS ON THE PARAMETERS Model
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2.4. THE SCALAR AND THE CMB ANGULAR
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2.4. THE SCALAR AND THE CMB ANGULAR
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2.5. DISCUSSION by the canonical sc
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Chapter 3 Non-local features in the
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3.1. MODELS AND METHODOLOGY on the
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3.1. MODELS AND METHODOLOGY values
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3.2. RESULTS Datasets WMAP-7 WMAP-7
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3.2. RESULTS 0.2 0.15 0.1 ∆ χ 2
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3.2. RESULTS 7000 150 6000 100 50 l
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3.3. DISCUSSION WMAP as well as the
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Chapter 4 Bi-spectra associated wit
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4.1. MODELS OF INTEREST AND POWER S
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4.1. MODELS OF INTEREST AND POWER S
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4.2. THE SCALAR BI-SPECTRUM IN THE
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4.3. THE NUMERICAL COMPUTATION OF T
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4.4. RESULTS IN THE EQUILATERAL LIM
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4.4. RESULTS IN THE EQUILATERAL LIM
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Chapter 5 The scalar bi-spectrum du
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5.1. BEHAVIOR OF BACKGROUND AND PER
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5.2. THE CONTRIBUTIONS TO THE BI-SP
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5.3. DISCUSSION significant during
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Chapter 6 Effects of primordial fea
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6.1. MODELS AND COMPARISON WITH THE
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6.2. FROM THE PRIMORDIAL SPECTRUM T
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6.3. THE NUMERICAL METHODS: ESSENTI
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6.4. RESULTS Model Quadratic Quadra
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6.4. RESULTS 6e-09 Quadratic potent
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6.4. RESULTS 30 4 20 Change in R Ch
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6.5. DISCUSSION wherein one works w
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Chapter 7 Imprints of primordial no
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7.1. FORMALISM and the LSS studies.
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7.1. FORMALISM only mildly non-line
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7.1. FORMALISM If the bi-spectrum c
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7.2. RESULTS 0.12 0.13 2e3 , 2.2e3
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7.3. CONCLUSIONS 7.3 Conclusions To
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Chapter 8 Summary and outlook In th
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8.2. OUTLOOK factorily [69, 70]. Ra
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Bibliography [1] See,http://magnum.
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BIBLIOGRAPHY [27] See,http://cfht.h
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BIBLIOGRAPHY [55] F. Arroja, A. E.
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BIBLIOGRAPHY [77] R. K. Jain, P. Ch
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BIBLIOGRAPHY [103] R. Allahverdi, J
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BIBLIOGRAPHY [132] S. Sasaki, Publ.
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PHYS08200605006 D.K. Hazra - Homi Bhabha National Institute

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