34 research outputs found
Spectral Distortions of the CMB as a Probe of Inflation, Recombination, Structure Formation and Particle Physics
Following the pioneering observations with COBE in the early 1990s, studies
of the cosmic microwave background (CMB) have focused on temperature and
polarization anisotropies. CMB spectral distortions - tiny departures of the
CMB energy spectrum from that of a perfect blackbody - provide a second,
independent probe of fundamental physics, with a reach deep into the primordial
Universe. The theoretical foundation of spectral distortions has seen major
advances in recent years, which highlight the immense potential of this
emerging field. Spectral distortions probe a fundamental property of the
Universe - its thermal history - thereby providing additional insight into
processes within the cosmological standard model (CSM) as well as new physics
beyond. Spectral distortions are an important tool for understanding inflation
and the nature of dark matter. They shed new light on the physics of
recombination and reionization, both prominent stages in the evolution of our
Universe, and furnish critical information on baryonic feedback processes, in
addition to probing primordial correlation functions at scales inaccessible to
other tracers. In principle the range of signals is vast: many orders of
magnitude of discovery space could be explored by detailed observations of the
CMB energy spectrum. Several CSM signals are predicted and provide clear
experimental targets, some of which are already observable with present-day
technology. Confirmation of these signals would extend the reach of the CSM by
orders of magnitude in physical scale as the Universe evolves from the initial
stages to its present form. The absence of these signals would pose a huge
theoretical challenge, immediately pointing to new physics.Comment: Astro2020 Science White Paper, 5 pages text, 13 pages in total, 3
Figures, minor update to reference
Exploring cosmic origins with CORE : Inflation
We forecast the scientific capabilities to improve our understanding of cosmic inflation of CORE, a proposed CMB space satellite submitted in response to the ESA fifth call for a medium-size mission opportunity. The CORE satellite will map the CMB anisotropies in temperature and polarization in 19 frequency channels spanning the range 60-600 GHz. CORE will have an aggregate noise sensitivity of 1.7 mu K.arcmin and an angular resolution of 5' at 200 GHz. We explore the impact of telescope size and noise sensitivity on the inflation science return by making forecasts for several instrumental configurations. This study assumes that the lower and higher frequency channels suffice to remove foreground contaminations and complements other related studies of component separation and systematic effects, which will be reported in other papers of the series "Exploring Cosmic Origins with CORE." We forecast the capability to determine key inflationary parameters, to lower the detection limit for the tensor-to-scalar ratio down to the 10(-3) level, to chart the landscape of single field slow-roll inflationary models, to constrain the epoch of reheating, thus connecting inflation to the standard radiation-matter dominated Big Bang era, to reconstruct the primordial power spectrum, to constrain the contribution from isocurvature perturbations to the 10(-3) level, to improve constraints on the cosmic string tension to a level below the presumptive GUT scale, and to improve the current measurements of primordial non-Gaussianities down to the f(NL)(local) <1 level. For all the models explored, CORE alone will improve significantly on the present constraints on the physics of inflation. Its capabilities will be further enhanced by combining with complementary future cosmological observations.Peer reviewe
Exploring Cosmic Origins with CORE: Survey requirements and mission design
Future observations of cosmic microwave background (CMB) polarisation havethe potential to answer some of the most fundamental questions of modernphysics and cosmology. In this paper, we list the requirements for a future CMBpolarisation survey addressing these scientific objectives, and discuss thedesign drivers of the CORE space mission proposed to ESA in answer to the "M5"call for a medium-sized mission. The rationale and options, and themethodologies used to assess the mission's performance, are of interest toother future CMB mission design studies. CORE is designed as a near-ultimateCMB polarisation mission which, for optimal complementarity with ground-basedobservations, will perform the observations that are known to be essential toCMB polarisation scienceand cannot be obtained by any other means than adedicated space mission
Exploring cosmic origins with CORE: Survey requirements and mission design
Future observations of cosmic microwave background (CMB) polarisation have
the potential to answer some of the most fundamental questions of modern
physics and cosmology. In this paper, we list the requirements for a future CMB
polarisation survey addressing these scientific objectives, and discuss the
design drivers of the CORE space mission proposed to ESA in answer to the "M5"
call for a medium-sized mission. The rationale and options, and the
methodologies used to assess the mission's performance, are of interest to
other future CMB mission design studies. CORE is designed as a near-ultimate
CMB polarisation mission which, for optimal complementarity with ground-based
observations, will perform the observations that are known to be essential to
CMB polarisation scienceand cannot be obtained by any other means than a
dedicated space mission.Comment: 79 pages, 14 figure
Effect of Phase and Range Gate Pull-Off Delay Quantization on Jammer Signal
The analysis of jamming signals emitted by electronic countermeasure (ECM) systems after phase quantisation, performed by radio frequency digital memory devices, and after introduction of increasing time delay, is approached. The analysis shows the exact expression of the spectrum of a phase-quantised jamming signal when the quantisation levels are equally spaced. The spectrum of the signal presents a main term that is simply an attenuated version of the signal received by the ECM system, and spurious terms whose amplitude and position depend on the number of quantisation levels. The effect of time delay quantisation introduced by range gate pull-off devices is analytically evaluated, in combination to the phase quantisation. Results show that this second distortion can be generally neglected with respect to the spurious terms because of the phase quantisation, particularly when the number of phase quantisation bits is lo