Searching the Cosmos: Ripples from Avant-Garde Cosmological Probes
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Philippa Hartley Title Abstract
Philippa Hartley Title Cosmic telescopes: witnessing the emission mechanism of radio quiet quasars Abstract The quasar model has reached relative maturity: we know that light is emitted at great power across the electromagnetic spectrum from the active nuclei of distant galaxies, where violent accretion processes release huge amounts of energy from gravitational stores. We observe that, in some quasars, matter falling onto the central black hole is funnneled into dramatic jets, emitting radio light across galactic distances. Over cosmic history the quasar population peaked in unison with star formation activity, leading us to suspect the role of quasars in the quenching of star-formation. Missing from the picture, however, is a full understanding of how such feedback processes manifest in the vast majority of quasars: those objects with very little radio emission. In these 'radio-quiet' quasars, jets appear to be absent, and it is possible that the faint radio signal that we do detect is the result either of smaller-scale AGN activity, of continued star formation, or of both. Only by undestanding the source of this very faint emission can we fully understand the quasar stage of galaxy evolution. This talk presents findings using strong gravitational lenses as 'cosmic telescopes' that magnify distant source structure, allowing us to resolve these intriguing objects to the sub-parsec scale. Philippa Hartley SKA Organisation, Jodrell Bank Observatory, Cheshire, SK11 9FT, UK +44 (0)161 306 9600 · [email protected] RESEARCH INTERESTS -
Controlling and Leveraging Small-Scale Information in Tomographic Galaxy-Galaxy Lensing
MNRAS 000,1{13 (2015) Preprint 19 March 2019 Compiled using MNRAS LATEX style file v3.0 Controlling and leveraging small-scale information in tomographic galaxy-galaxy lensing Niall MacCrann1;2?, Jonathan Blazek3, Bhuvnesh Jain4 and Elisabeth Krause5 1 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA 2 Department of Physics, The Ohio State University, Columbus, OH 43210, USA 3 Institute of Physics, Laboratory of Astrophysics, Ecole´ Polytechnique F´ed´erale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland 4 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 5 Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA Accepted XXX. Received YYY; in original form ZZZ ABSTRACT The tangential shear signal receives contributions from physical scales in the galaxy- matter correlation function well below the transverse scale at which it is measured. Since small scales are difficult to model, this non-locality has generally required strin- gent scale cuts or new statistics for cosmological analyses. Using the fact that uncer- tainty in these contributions corresponds to an uncertainty in the enclosed projected mass around the lens, we provide an analytic marginalization scheme to account for this. Our approach enables the inclusion of measurements on smaller scales with- out requiring numerical sampling over extra free parameters. We extend the analytic marginalization formalism to retain cosmographic (\shear-ratio") information from small-scale measurements that would otherwise be removed due to modeling uncer- tainties, again without requiring the addition of extra sampling parameters. We test the methodology using simulated likelihood analysis of a DES Year 5-like galaxy- galaxy lensing and galaxy clustering datavector. -
Small-Scale Anisotropies of the Cosmic Microwave Background: Experimental and Theoretical Perspectives
Small-Scale Anisotropies of the Cosmic Microwave Background: Experimental and Theoretical Perspectives Eric R. Switzer A DISSERTATION PRESENTED TO THE FACULTY OF PRINCETON UNIVERSITY IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY RECOMMENDED FOR ACCEPTANCE BY THE DEPARTMENT OF PHYSICS [Adviser: Lyman Page] November 2008 c Copyright by Eric R. Switzer, 2008. All rights reserved. Abstract In this thesis, we consider both theoretical and experimental aspects of the cosmic microwave background (CMB) anisotropy for ℓ > 500. Part one addresses the process by which the universe first became neutral, its recombination history. The work described here moves closer to achiev- ing the precision needed for upcoming small-scale anisotropy experiments. Part two describes experimental work with the Atacama Cosmology Telescope (ACT), designed to measure these anisotropies, and focuses on its electronics and software, on the site stability, and on calibration and diagnostics. Cosmological recombination occurs when the universe has cooled sufficiently for neutral atomic species to form. The atomic processes in this era determine the evolution of the free electron abundance, which in turn determines the optical depth to Thomson scattering. The Thomson optical depth drops rapidly (cosmologically) as the electrons are captured. The radiation is then decoupled from the matter, and so travels almost unimpeded to us today as the CMB. Studies of the CMB provide a pristine view of this early stage of the universe (at around 300,000 years old), and the statistics of the CMB anisotropy inform a model of the universe which is precise and consistent with cosmological studies of the more recent universe from optical astronomy. -
Potential Sources of Contamination to Weak Lensing Measurements
Mon. Not. R. Astron. Soc. 000, 1–12 (2006) Printed 13 March 2018 (MN LATEX style file v2.2) Potential sources of contamination to weak lensing measurements: constraints from N-body simulations Catherine Heymans1⋆, Martin White2,3, Alan Heavens4, Chris Vale5,2 & Ludovic Van Waerbeke1 1 Department of Physics and Astronomy, 6224 Agricultural Road, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada. 2 Department of Physics and Astronomy, 601 Campbell Hall, University of California Berkeley, CA 94720, USA. 3 Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA. 4 SUPA†, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK. 5 Theoretical Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510, USA. 13 March 2018 ABSTRACT We investigate the expected correlation between the weak gravitational shear of distant galaxies and the orientation of foreground galaxies, through the use of numerical simulations. This shear-ellipticity correlation can mimic a cosmological weak lensing signal, and is poten- tially the limiting physical systematic effect for cosmology with future high-precision weak lensing surveys. We find that, if uncorrected, the shear-ellipticity correlation could contribute up to 10% of the weak lensing signal on scales up to 20 arcminutes, for lensing surveys with a median depth zm =1. The most massive foregroundgalaxies are expected to cause the largest correlations, a result also seen in the Sloan Digital Sky Survey. We find that the redshift de- pendence of the effect is proportional to the lensing efficiency of the foreground, and this offers prospects for removal to high precision, although with some model dependence. -
Cosmic Visions Dark Energy: Science
Cosmic Visions Dark Energy: Science Scott Dodelson, Katrin Heitmann, Chris Hirata, Klaus Honscheid, Aaron Roodman, UroˇsSeljak, Anˇze Slosar, Mark Trodden Executive Summary Cosmic surveys provide crucial information about high energy physics including strong evidence for dark energy, dark matter, and inflation. Ongoing and upcoming surveys will start to identify the underlying physics of these new phenomena, including tight constraints on the equation of state of dark energy, the viability of modified gravity, the existence of extra light species, the masses of the neutrinos, and the potential of the field that drove inflation. Even after the Stage IV experiments, DESI and LSST, complete their surveys, there will still be much information left in the sky. This additional information will enable us to understand the physics underlying the dark universe at an even deeper level and, in case Stage IV surveys find hints for physics beyond the current Standard Model of Cosmology, to revolutionize our current view of the universe. There are many ideas for how best to supplement and aid DESI and LSST in order to access some of this remaining information and how surveys beyond Stage IV can fully exploit this regime. These ideas flow to potential projects that could start construction in the 2020's. arXiv:1604.07626v1 [astro-ph.CO] 26 Apr 2016 2 1 Overview This document begins with a description of the scientific goals of the cosmic surveys program in x2 and then x3 presents the evidence that, even after the surveys currently planned for the 2020's, much of the relevant information in the sky will remain to be mined. -
Prospects for Weak Lensing Studies with New Radio Telescopes
PROSPECTS FOR WEAK LENSING STUDIES WITH NEW RADIO TELESCOPES MICHAEL L. BROWN Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL I consider the prospects for performing weak lensing studies with the new generation of radio telescopes that are coming online now and in the future. I include a description of a proposed technique to use polarization observations in radio weak lensing analyses which could prove extremely useful for removing a contaminating signal from intrinsic alignments. Ultimately, the Square Kilometre Array promises to be an exceptional instrument for performing weak lensing studies due to the high resolution, large area surveys which it will perform. In the nearer term, the e-MERLIN instrument in the UK offers the high sensitivity and sub-arcsec resolution required to prove weak lensing techniques in the radio band. I describe the Su- perCLASS survey – a recently accepted e-MERLIN legacy programme which will perform a pioneering radio weak lensing analysis of a supercluster of galaxies. 1 Weak lensing in the radio band Weak gravitational lensing is the coherent distortion in the images of faint background galaxies due to gravitational light deflection caused by intervening (dark) matter distributions. On the very largest scales, the effect traces the large scale structure of the Universe and is known as cosmic shear. The vast majority of weak lensing surveys to date have been conducted in the optical bands since large numbers of background galaxies are required in order to measure the small (∼ a few %) distortions. However, a new generation of powerful radio facilities is now imminent which makes weak lensing in the radio band a viable alternative. -
Annual Review 2011/12
UCL DEPARTMENT OF PHYSICS AND ASTRONOMY PHYSICS AND ASTRONOMY 2011–12 ANNUAL REVIEW PHYSICS AND ASTRONOMY ANNUAL REVIEW 2011–12 Contents Welcome It is an honour to write this WELCOME 1 introduction standing, to misquote Newton, on the shoulders of giants. COMMUNITY FOCUS 3 Jonathan Tennyson finished his Teaching Lowdown 4 tenure as Head of Department in September 2011 and so the majority Student Accolades 4 of the material contained in this Outstanding PhD Theses Published 5 Review records achievements under his leadership. In addition, Tony Career Profiles 6 Harker is currently acting as Head of Science in Action 8 Department in many matters and will continue to do so until October 2012. Alumni Matters 9 This is due to my on-going commitments with the ATLAS experiment on the ACADEMIC SHOWCASE 11 Large Hadron Collider (LHC) at CERN. Staff Accolades 12 I currently spend a large amount of my time in Geneva and I am very grateful Academic Appointments 14 to both Tony and Jonathan, as well as to other members of staff for helping Doctor of Philosophy (PhD) 15 to make this transition a success. In Portrait of Dr Phil Jones 16 particular I would also like to thank Hilary Wigmore as Departmental Manager and Raman Prinja as the new Director of RESEARCH SPOTLIGHT 17 Teaching for their continued support. Atomic, Molecular, Optical and Position Physics (AMOPP) 19 High Energy Physics (HEP) 21 “Success in such long- Condensed Matter and term, high-impact projects Materials Physics (CMMP) 25 requires sustained vision Astrophysics (Astro) 29 and dedicated work by Biological Physics (BioP) 33 excellent scientists over Research Statistics 35 many years.” Staff Snapshot 38 Underpinning this success is the outstanding quality of scientific research and education within the Department. -
Astro2020 Science White Paper Primordial Non-Gaussianity
Astro2020 Science White Paper Primordial Non-Gaussianity Thematic Areas: Cosmology and Fundamental Physics Principal Author: Name: P. Daniel Meerburg Institution: University of Cambridge Email: [email protected] Abstract: Our current understanding of the Universe is established through the pristine measurements of structure in the cosmic microwave background (CMB) and the distribution and shapes of galaxies tracing the large scale structure (LSS) of the Universe. One key ingredient that underlies cosmological observables is that the field that sources the observed structure is assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianity is perhaps the most robust theoretical prediction of models that explain the observed Universe; it is necessarily present even in the simplest scenarios. In addition, most inflationary models produce far higher levels of non-Gaussianity. Since non-Gaussianity directly probes the dynamics in the early Universe, a detection would present a monumental discovery in cosmology, providing clues about physics at energy scales as high as the GUT scale. This white paper aims to motivate a continued search to obtain evidence for deviations from Gaussianity in the primordial Universe. Since the previous decadal, important advances have been made, both theoretically and observationally, which have further established the importance of deviations from Gaussianity in cosmology. Foremost, primordial non-Gaussianities are now very tightly constrained by the CMB. Second, models motivated by stringy physics suggest detectable signatures of primordial non-Gaussianities with a unique shape which has not been considered in previous searches. Third, improving constraints using LSS requires a better understanding how to disentangle non-Gaussianities sourced at late times from those sourced by the physics in the early Universe. -
The Practical Use of Cosmic Shear As a Probe of Gravity
The Practical use of Cosmic Shear as a Probe of Gravity Donnacha Kirk Thesis submitted for the Degree of Doctor of Philosophy of the University College London Department of Physics & Astronomy UNIVERSITY COLLEGE LONDON April 2011 I, Donnacha Kirk, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Specifically: • The work on luminosity functions and red galaxy fractions in section 2.7 was done by Dr. Michael Schneider (then at Durham) as part of our collaboration on the paper Kirk et al. (2010). • The work in chapters 3 & 4 is my contribution to, and will form the substantial part of, papers in preparation with collaborators Prof. Rachel Bean and Istvan Lazslo at Cornell University. The MG effect on the linear growth function was computed by Istvan Lazslo. • The Great08 section of chapter 6 draws on my contributions to the Great08 Handbook (Bridle et al. 2009), Great08 Results Paper (Bridle et al. 2010a) and Great10 Handbook (Kitching et al. 2010). To Mum and Dad, for everything. Boyle. ... an’ it blowed, an’ blowed – blew is the right word, Joxer, but blowed is what the sailors use... Joxer. Aw, it’s a darlin’ word, a daarlin’ word. Boyle. An’, as it blowed an’ blowed, I often looked up at the sky an’ assed meself the question – what is the stars, what is the stars? Voice of Coal Vendor. Any blocks, coal-blocks; blocks, coal-blocks! Joxer. Ah, that’s the question, that’s the question – what is the stars? Boyle. -
The Very Small Array: Latest Results and Future Plans
The Very Small Array: latest results and future plans Keith Grainge Astrophysics Group, Cavendish Laboratory, Cambridge Rencontres de Moriond, 31 March 2004 OVERVIEW The Very Small Array (VSA) • Current primordial observations • The S-Z effect • Planned upgrades to the instrument • Future science at high ` • Summary • 1 THE VSA CONSORTIUM Cavendish Astrophysics Group Roger Boysen Tony Brown Chris Clementson Mike Crofts Jerry Czeres Roger Dace Keith Grainge (PM) Mike Hobson (PI) Mike Jones Rüdiger Kneissl Katy Lancaster Anthony Lasenby Klaus Maisinger Ian Northrop Guy Pooley Vic Quy Nutan Rajguru Ben Rusholme Richard Saunders Richard Savage Anna Scaife Jack Schofield Paul Scott (Former PI) Clive Shaw Anze Slosar Angela Taylor David Titterington Elizabeth Waldram Brian Wood Jodrell Bank Observatory Colin Baines Richard Battye Eddie Blackhurst Pedro Carreira Kieran Cleary Rod Davies Richard Davis Clive Dickinson Yaser Hafez Mark Polkey Bob Watson Althea Wilkinson Instituto de Astrofísica de Canarias Jose Alberto Rubiño-Martin Carlos Guiterez Rafa Rebolo Lopez Pedro Sosa-Molina Ricardo Genova-Santos 2 THE VERY SMALL ARRAY (VSA) Sited on Observatorio del Teide, Tenerife • 14 antennas 91 baselines • ) Observing frequency ν = 26 36 GHz; bandwidth ∆ν = 1:5 GHz • − Compact configuration: 143 mm horns; ` = 150 800; ∆` 90 (without • − ≈ mosaicing); Sept 2000 – Sept 2001 Extended configuration: 322 mm horns; ` = 300 1800; ∆` 200 (without • − ≈ mosaicing); Sept 2001 – present 3 COMPARISON WITH OTHER CMB EXPERIMENTS Different systematics from “single-dish” experiments: • – negligible pointing error – negligible beam uncertainty Different from other CMB interferometers (DASI, CBI): • – RT survey and dedicated source subtraction 2-element interferometer remove effect of extragalactic point sources ) – tracking elements rather than comounted can apply fringe rate filter to remove unwanted signals. -
Cosmic Shear: Inference from Forward Models
Cosmic Shear: Inference from Forward Models Peter L. Taylor,1, ∗ Thomas D. Kitching,1 Justing Alsing,2, 3, 4 Benjamin D. Wandelt,2, 5, 6, 7 Stephen M. Feeney,2 and Jason D. McEwen1 1Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK 2Center for Computational Astrophysics, Flatiron Institute, 162 5th Ave, New York City, NY 10010, USA 3Oskar Klein Centre for Cosmoparticle Physics, Stockholm University, AlbaNova, Stockholm SE-106 91, Sweden 4Imperial Centre for Inference and Cosmology, Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK 5Sorbonne Universit´e,CNRS, UMR 7095, Institut d'Astrophysique de Paris, 98 bis boulevard Arago, 75014 Paris, France 6Sorbonne Universit´e,Institut Lagrange de Paris (ILP), 98 bis boulevard Arago, 75014 Paris, France 7Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08540, USA Density-estimation likelihood-free inference (DELFI) has recently been proposed as an effi- cient method for simulation-based cosmological parameter inference. Compared to the standard likelihood-based Markov Chain Monte Carlo (MCMC) approach, DELFI has several advantages: it is highly parallelizable, there is no need to assume a possibly incorrect functional form for the likelihood and complicated effects (e.g the mask and detector systematics) are easier to handle with forward models. In light of this, we present two DELFI pipelines to perform weak lensing parameter inference with lognormal realizations of the tomographic shear field { using the C` summary statis- tic. The first pipeline accounts for the non-Gaussianities of the shear field, intrinsic alignments and photometric-redshift error. -
Sum of the Masses of the Milky Way and M31: a Likelihood-Free Inference Approach Pablo Lemos, Niall Jeffrey, Lorne Whiteway, Ofer Lahav, Noam I
Sum of the masses of the Milky Way and M31: A likelihood-free inference approach Pablo Lemos, Niall Jeffrey, Lorne Whiteway, Ofer Lahav, Noam I. Libeskind, Yehuda Hoffman To cite this version: Pablo Lemos, Niall Jeffrey, Lorne Whiteway, Ofer Lahav, Noam I. Libeskind, et al.. Sum ofthe masses of the Milky Way and M31: A likelihood-free inference approach. Phys.Rev.D, 2021, 103 (2), pp.023009. 10.1103/PhysRevD.103.023009. hal-02999468 HAL Id: hal-02999468 https://hal.archives-ouvertes.fr/hal-02999468 Submitted on 26 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. PHYSICAL REVIEW D 103, 023009 (2021) Sum of the masses of the Milky Way and M31: A likelihood-free inference approach Pablo Lemos ,1,* Niall Jeffrey ,2,1 Lorne Whiteway ,1 Ofer Lahav,1 Noam Libeskind I,3,4 and Yehuda Hoffman5 1Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom 2Laboratoire de Physique de l’Ecole Normale Sup´erieure, ENS, Universit´e PSL, CNRS, Sorbonne Universit´e, Universit´e de Paris, Paris, France 3Leibniz-Institut