Seminar on intrinsic galaxy shape alignments in the latest large area cosmic shear surveys.

"Seminar on intrinsic galaxy shape alignments in the latest large area cosmic shear surveys.", Stanford 16th May 2016

Transcript

1. Dark Energy Survey 1 Donnacha Kirk, UCL DARK ENERGY SURVEY Galaxy Alignments: DES, SPT and how cosmological probes are more than the sum of their parts…
2. The Dark Energy Survey Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Probe origin of Cosmic Acceleration: Distance vs. redshift Growth of Structure • Two multicolor surveys: 300 M galaxies over 5000 s.d. grizY to 24th mag 3500 supernovae (30 sq deg) • New camera for CTIO Blanco 4m telescope Facility instrument - 570 Mpixels - 3 deg2 FOV - Facility instrument • Five-year Survey started Aug. 31, 2013 525 nights (Sept.-Feb.) - Science Verification (SV) - Nov 2012-Feb 2013 -Year 3 started August 2015 DECam on the CTIO Blanco 4m www.darkenergysurvey.org www.darkenergydetectives.org
3. The Dark Energy Survey Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Probe origin of Cosmic Acceleration: Distance vs. redshift Growth of Structure • Two multicolor surveys: 300 M galaxies over 5000 s.d. grizY to 24th mag 3500 supernovae (30 sq deg) • New camera for CTIO Blanco 4m telescope Facility instrument - 570 Mpixels - 3 deg2 FOV - Facility instrument • Five-year Survey started Aug. 31, 2013 525 nights (Sept.-Feb.) - Science Verification (SV) - Nov 2012-Feb 2013 -Year 3 started August 2015 DECam on the CTIO Blanco 4m www.darkenergysurvey.org www.darkenergydetectives.org
4. Survey Progress (Y1+Y2+Y3 as of 05 Jan 2016)
5. THE DARK ENERGY SURVEY Designed to measure four cosmological probes simultaneously: Weak Lensing (distance, structure growth) Shape and measurements of 200 million galaxies Galaxy Clusters (distance, structure growth) Tens of thousands of clusters up to z~1, synergies with SPT, VHS Type Ia Supernovae (distance) Standard candles. 3500 SNIa to z~1 Large-Scale Structure (distance) Standard Ruler 300 million galaxies to z~1 and beyond
6. SV Papers Weak Lensing Large-scale Structure Supernovae DES 2015-0085 FERMILAB-PUB-16-003-AE Mon. Not. R. Astron. Soc. 000, 1–?? (2002) Printed 27 January 2016 (MN L ATEX style file v2.2) The Dark Energy Survey: more than dark energy - an overview Dark Energy Survey Collaboration: T. Abbott1, F. B. Abdalla2, S. Allam3, J. Aleksi´ c50, A. Amara4, D. Bacon6, E. Balbinot49, M. Banerji7,8, K. Bechtol59,60, A. Benoit-L´ evy15,2,14, G. M. Bernstein10, E. Bertin14,15, J. Blazek16, S. Dodelson3,29,61, C. Bonnett17, D. Brooks2, S. Bridle18, R. J. Brunner44,22, E. Buckley-Geer3, D. L. Burke11,19, D. Capozzi6, G. B. Caminha54,55, J. Carlsen6, A. Carnero-Rosell20,21, M. Carollo57, M. Carrasco-Kind22,23, J. Carretero9,50, F. J. Castander9, L. Clerkin2, T. Collett6, C. Conselice58, M. Crocce9, C. E. Cunha11, C. B. D’Andrea6, L. N. da Costa21,20, T. M. Davis52, S. Desai26,27, H. T. Diehl3, J. P. Dietrich28,26, P. Doel2, A. Drlica-Wagner3, J. Etherington6, J. Estrada3, A. E. Evrard24,31, J. Fabbri2, D. A. Finley3, B. Flaugher3, P. Fosalba9, R. J. Foley23,44, J. Frieman29,3, J. Garc´ ıa-Bellido46, E. Gaztanaga9, D. W. Gerdes24, T. Giannantonio8,7, D. A. Goldstein47,40, D. Gruen19,11, R. A. Gruendl22,23, P. Guarnieri6, G. Gutierrez3, W. Hartley4, K. Honscheid16,34, B. Jain10, D. J. James1, T. Jeltema56, S. Jouvel2, R. Kessler29, A. King52, D. Kirk2, R. Kron29, K. Kuehn35, N. Kuropatkin3, O. Lahav2,?, T. S. Li25, M. Lima21,37, H. Lin3, M. A. G. Maia21,20, M. Makler54, M. Manera2, C. Maraston6, J. L. Marshall25, P. Martini16,38, R. G. McMahon7,8, P. Melchior5, A. Merson2, C. J. Miller31,24, R. Miquel39,50, J. J. Mohr32,27,26, X. Morice-Atkinson6, K. Naidoo2, E. Neilsen3, R. C. Nichol6, B. Nord3, R. Ogando21,20, F. Ostrovski7,8, A. Palmese2, A. Papadopoulos6,51, H. Peiris2, J. Peoples3, A. A. Plazas30, W. J. Percival6, S. L. Reed7,8, A. K. Romer41, A. Roodman19,11, A. Ross16, E. Rozo62, E. S. Rykoff11,19, I. Sadeh2, M. Sako10, C. S´ anchez50, E. Sanchez33, B. Santiago48, V. Scarpine3, M. Schubnell24, I. Sevilla-Noarbe33,23, E. Sheldon43, M. Smith53, R. C. Smith1, M. Soares- Santos3, F. Sobreira3,21, M. Soumagnac2, E. Suchyta10, M. Sullivan53, M. Swanson63, G. Tarle24, J. Thaler44, D. Thomas6,45, R. C. Thomas40, D. Tucker3, J. D. Vieira23,44,22, V. Vikram36, A. R. Walker1, R. H. Wechsler11,19, W. Wester3, J. Weller32,26,28, L. Whiteway2, H. Wilcox6, B. Yanny3, Y. Zhang24, J. Zuntz18 ? Corresponding author: o.lahav@ucl.ac.uk Accepted 2015 ???. Received 2015 ???; in original form 2015 ??? ABSTRACT This overview article describes the legacy prospect and discovery potential of the Dark En- ergy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterise dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from ‘Science Verification’, and from the first, second and third seasons of observations), what DES can tell us about the solar system, the Milky Way, galaxy evolution, quasars, and other topics. In addition, we show that if the cosmolog- ical model is assumed to be ⇤ + Cold Dark Matter (LCDM) then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the dis- covery of 34 Trans Neptunian Objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed). Key words: surveys – galaxies – Galaxy – quasars – supernovae – minor plantes, asteroids c 2002 RAS arXiv:1601.00329v2 [astro-ph.CO] 26 Jan 2016 Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey A. Drlica-Wagner1,⇤, K. Bechtol2,3,†, E. S. Ryko↵4,5, E. Luque6,7, A. Queiroz6,7, Y.-Y. Mao8,4,5, R. H. Wechsler8,4,5, J. D. Simon9, B. Santiago6,7, B. Yanny1, E. Balbinot10,7, S. Dodelson1,11, A. Fausti Neto7, D. J. James12, T. S. Li13, M. A. G. Maia7,14, J. L. Marshall13, A. Pieres6,7, K. Stringer13, A. R. Walker12, T. M. C. Abbott12, F. B. Abdalla15,16, S. Allam1, A. Benoit-L´ evy15, G. M. Bernstein17, E. Bertin18,19, D. Brooks15, E. Buckley-Geer1, D. L. Burke4,5, A. Carnero Rosell7,14, M. Carrasco Kind20,21, J. Carretero22,23, M. Crocce22, L. N. da Costa7,14, S. Desai24,25, H. T. Diehl1, J. P. Dietrich24,25, P. Doel15, T. F. Eifler17,26, A. E. Evrard27,28, D. A. Finley1, B. Flaugher1, P. Fosalba22, J. Frieman1,11, E. Gaztanaga22, D. W. Gerdes28, D. Gruen29,30, R. A. Gruendl20,21, G. Gutierrez1, K. Honscheid31,32, K. Kuehn33, N. Kuropatkin1, O. Lahav15, P. Martini31,34, R. Miquel35,23, B. Nord1, R. Ogando7,14, A. A. Plazas26, K. Reil5, A. Roodman4,5, M. Sako17, E. Sanchez36, V. Scarpine1, M. Schubnell28, I. Sevilla-Noarbe36,20, R. C. Smith12, M. Soares-Santos1, F. Sobreira1,7, E. Suchyta31,32, M. E. C. Swanson21, G. Tarle28, D. Tucker1, V. Vikram37, W. Wester1, Y. Zhang28, J. Zuntz38 (The DES Collaboration) arXiv:1508.03622v2 [astro-ph.GA] 6 Nov 2015 Draft version February 19, 2016 Preprint typeset using L A TEX style emulateapj v. 5/2/11 A DARK ENERGY CAMERA SEARCH FOR AN OPTICAL COUNTERPART TO THE FIRST ADVANCED LIGO GRAVITATIONAL WAVE EVENT GW150914 M. Soares-Santos1, R. Kessler2, E. Berger3, J. Annis1, D. Brout4, E. Buckley-Geer1, H. Chen2, P. S. Cowperthwaite3, H. T. Diehl1, Z. Doctor2, A. Drlica-Wagner1, B. Farr2, D. A. Finley1, B. Flaugher1, R. J. Foley5,6, J. Frieman1,2, R. A. Gruendl5,7, K. Herner1, D. Holz2, H. Lin1, J. Marriner1, E. Neilsen1, A. Rest8, M. Sako4, D. Scolnic2, F. Sobreira9, A. R. Walker10, W. Wester1, B. Yanny1, T. M. C. Abbott10, F. B. Abdalla11,12, S. Allam1, R. Armstrong13, M. Banerji14,15, A. Benoit-L´ evy16,11,17, R. A. Bernstein18, E. Bertin16,17, D. A. Brown19, D. L. Burke20,21, D. Capozzi22, A. Carnero Rosell23,24, M. Carrasco Kind5,7, J. Carretero25,26, F. J. Castander25, S. B. Cenko27,28, R. Chornock29, M. Crocce25, C. B. D’Andrea22,30, L. N. da Costa23,24, S. Desai31,32, J. P. Dietrich32,31, M. R. Drout3, T. F. Eifler4,33, J. Estrada1, A. E. Evrard34,35, S. Fairhurst36, E. Fernandez26, J. Fischer4, W. Fong37, P. Fosalba25, D. B. Fox38, C. L. Fryer39, J. Garcia-Bellido40, E. Gaztanaga25, D. W. Gerdes35, D. A. Goldstein41,42, D. Gruen20,21, G. Gutierrez1, K. Honscheid43,44, D. J. James10, I. Karliner6, D. Kasen45,46, S. Kent1, N. Kuropatkin1, K. Kuehn47, O. Lahav11, T. S. Li48, M. Lima49,23, M. A. G. Maia23,24, R. Margutti50, P. Martini43,51, T. Matheson52, R. G. McMahon14,15, B. D. Metzger53, C. J. Miller34,35, R. Miquel54,26, J. J. Mohr31,32,55, R. C. Nichol22, B. Nord1, R. Ogando23,24, J. Peoples1, A. A. Plazas33, E. Quataert56, A. K. Romer57, A. Roodman20,21, E. S. Rykoff20,21, E. Sanchez40, V. Scarpine1, R. Schindler21, M. Schubnell35, I. Sevilla-Noarbe40,5, E. Sheldon58, M. Smith30, N. Smith59, R. C. Smith10, A. Stebbins1, P. J. Sutton60, M. E. C. Swanson7, G. Tarle35, J. Thaler6, R. C. Thomas42, D. L. Tucker1, V. Vikram61, R. H. Wechsler62,20,21, J. Weller31,55,63 (The DES Collaboration) Draft version February 19, 2016 ABSTRACT We report initial results of a deep search for an optical counterpart to the gravitational wave event GW150914, the first trigger from the Advanced LIGO gravitational wave detectors. We used the Dark Energy Camera (DECam) to image a 102 deg2 area, corresponding to 38% of the initial trigger high- probability sky region and to 11% of the revised high-probability region. We observed in i and z bands at 4–5, 7, and 24 days after the trigger. The median 5 point-source limiting magnitudes of our search images are i = 22.5 and z = 21.8 mag. We processed the images through a di↵erence-imaging pipeline using templates from pre-existing Dark Energy Survey data and publicly available DECam data. Due to missing template observations and other losses, our e↵ective search area subtends 40 deg2, corresponding to 12% total probability in the initial map and 3% of the final map. In this area, we search for objects that decline significantly between days 4–5 and day 7, and are undetectable by day 24, finding none to typical magnitude limits of i = 21.5,21.1,20.1 for object colors (i z) = 1,0, 1, respectively. Our search demonstrates the feasibility of a dedicated search program with DECam and bodes well for future research in this emerging field. Subject headings: binaries: close — catalogs — gravitational waves — stars: neutron — surveys 1 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA 2 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 4 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 5 Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA 6 Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA 7 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 8 STScI, 3700 San Martin Dr., Baltimore, MD 21218, USA 9 Instituto de F´ ısica Te´ orica, Universidade Estadual Paulista, ley Road, Cambridge CB3 0HA, UK 15 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 16 CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 17 Sorbonne Universit´ es, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 18 Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101, USA 19 Physics Department, Syracuse University, Syracuse, NY 13244 20 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA 21 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 22 Institute of Cosmology & Gravitation, University of arXiv:1602.04198v2 [astro-ph.CO] 18 Feb 2016 Draft version December 11, 2015 Preprint typeset using L ATEX style emulateapj v. 5/2/11 OBSERVATION AND CONFIRMATION OF SIX STRONG LENSING SYSTEMS IN THE DARK ENERGY SURVEY SCIENCE VERIFICATION DATA B. Nord1, E. Buckley-Geer1, H. Lin1, H. T. Diehl1, J. Helsby2, N. Kuropatkin1, A. Amara3, T. Collett4, S. Allam1, G. Caminha5, C. De Bom5, S. Desai6,7, H. D´ umet-Montoya8, M. Elidaiana da S. Pereira5, D. A. Finley1, B. Flaugher1, C. Furlanetto9, H. Gaitsch1, M. Gill10, K. W. Merritt1, A. More11, D. Tucker1, E. S. Rykoff12,10, E. Rozo13, F. B. Abdalla14,15, A. Agnello16, M. Auger17, R. J. Brunner18,19, M. Carrasco Kind18,19, F. J. Castander20, C. E. Cunha12, L. N. da Costa21,22, R. Foley18,23, D. W. Gerdes24, K. Glazebrook25, J. Gschwend21,22, W. Hartley3, R. Kessler2, D. Lagattuta26, G. Lewis27, M. A. G. Maia21,22, M. Makler5, F. Menanteau18,19, A. Niernberg28, D. Scolnic2, J. D. Vieira18,23,19, R. Gramillano18, T. M. C. Abbott29, M. Banerji17,30, A. Benoit-L´ evy31,14,32, D. Brooks14, D. L. Burke12,10, D. Capozzi4, A. Carnero Rosell21,22, J. Carretero20,33, C. B. D’Andrea4,34, J. P. Dietrich6,7, P. Doel14, A. E. Evrard35,24, J. Frieman1,2, E. Gaztanaga20, D. Gruen36,37, K. Honscheid38,39, D. J. James29, K. Kuehn40, T. S. Li41, M. Lima42,21, J. L. Marshall41, P. Martini38,43, P. Melchior38,44,39, R. Miquel45,33, E. Neilsen1, R. C. Nichol4, R. Ogando21,22, A. A. Plazas46, A. K. Romer47, M. Sako48, E. Sanchez49, V. Scarpine1, M. Schubnell24, I. Sevilla-Noarbe49,18, R. C. Smith29, M. Soares-Santos1, F. Sobreira1,21, E. Suchyta48, M. E. C. Swanson19, G. Tarle24, J. Thaler23, A. R. Walker29, W. Wester1, Y. Zhang24 (The DES Collaboration) 1 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA 2 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA 3 Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich, Switzerland 4 Institute of Cosmology & Gravitation, University of Portsmouth, Portsmouth, PO1 3FX, UK 5 ICRA, Centro Brasileiro de Pesquisas F´ ısicas, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ, Brazil 6 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany 7 Faculty of Physics, Ludwig-Maximilians University, Scheinerstr. 1, 81679 Munich, Germany 8 Universidade Federal do Rio de Janeiro - Campus Maca´ e, Rua Alo´ ısio Gomes da Silva, 50 - Granja dos Cavaleiros, Cep: 27930-560, Maca´ e, RJ, Brazil 9 University of Nottingham, School of Physics and Astronomy, Nottingham NG7 2RD, UK 10 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 11 Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan 12 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA 13 Department of Physics, University of Arizona, Tucson, AZ 85721, USA 14 Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, UK 15 Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa 16 Department of Physics and Astronomy, PAB, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA 17 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 18 Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA 19 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 20 Institut de Ci` encies de l’Espai, IEEC-CSIC, Campus UAB, Carrer de Can Magrans, s/n, 08193 Bellaterra, Barcelona, Spain 21 Laborat´ orio Interinstitucional de e-Astronomia - LIneA, Rua Gal. Jos´ e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 22 Observat´ orio Nacional, Rua Gal. Jos´ e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 23 Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA 24 Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA 25 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, Victoria 3122, Australia 26 Centre de Recherche Astrophysique de Lyon, Universit´ e de Lyon, Universit´ e Lyon 1, CNRS, Observatoire de Lyon; 9 avenue Charles Andr´ e, 69561 Saint-Genis Laval Cedex, France 27 Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, NSW 2006, Australia 28 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus OH 43210, USA 29 Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile 30 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 31 CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 32 Sorbonne Universit´ es, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 33 Institut de F´ ısica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain 34 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK 35 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA 36 Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany 37 Universit¨ ats-Sternwarte, Fakult¨ at f¨ ur Physik, Ludwig-Maximilians Universit¨ at M¨ unchen, Scheinerstr. 1, 81679 M¨ unchen, Germany 38 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA 39 Department of Physics, The Ohio State University, Columbus, OH 43210, USA 40 Australian Astronomical Observatory, North Ryde, NSW 2113, Australia 41 George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA 42 Departamento de F´ ısica Matem´ atica, Instituto de F´ ısica, Universidade de S˜ ao Paulo, CP 66318, CEP 05314-970, S˜ ao Paulo, SP, Brazil 43 Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA 44 Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA 45 Instituci´ o Catalana de Recerca i Estudis Avan¸ cats, E-08010 Barcelona, Spain 46 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA 47 Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton, BN1 9QH, UK 48 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA and 49 Centro de Investigaciones Energ´ eticas, Medioambientales y Tecnol´ ogicas (CIEMAT), Madrid, Spain arXiv:1512.03062v1 [astro-ph.CO] 9 Dec 2015 Other…
7. SV Papers Weak Lensing Large-scale Structure Supernovae DES 2015-0085 FERMILAB-PUB-16-003-AE Mon. Not. R. Astron. Soc. 000, 1–?? (2002) Printed 27 January 2016 (MN L ATEX style file v2.2) The Dark Energy Survey: more than dark energy - an overview Dark Energy Survey Collaboration: T. Abbott1, F. B. Abdalla2, S. Allam3, J. Aleksi´ c50, A. Amara4, D. Bacon6, E. Balbinot49, M. Banerji7,8, K. Bechtol59,60, A. Benoit-L´ evy15,2,14, G. M. Bernstein10, E. Bertin14,15, J. Blazek16, S. Dodelson3,29,61, C. Bonnett17, D. Brooks2, S. Bridle18, R. J. Brunner44,22, E. Buckley-Geer3, D. L. Burke11,19, D. Capozzi6, G. B. Caminha54,55, J. Carlsen6, A. Carnero-Rosell20,21, M. Carollo57, M. Carrasco-Kind22,23, J. Carretero9,50, F. J. Castander9, L. Clerkin2, T. Collett6, C. Conselice58, M. Crocce9, C. E. Cunha11, C. B. D’Andrea6, L. N. da Costa21,20, T. M. Davis52, S. Desai26,27, H. T. Diehl3, J. P. Dietrich28,26, P. Doel2, A. Drlica-Wagner3, J. Etherington6, J. Estrada3, A. E. Evrard24,31, J. Fabbri2, D. A. Finley3, B. Flaugher3, P. Fosalba9, R. J. Foley23,44, J. Frieman29,3, J. Garc´ ıa-Bellido46, E. Gaztanaga9, D. W. Gerdes24, T. Giannantonio8,7, D. A. Goldstein47,40, D. Gruen19,11, R. A. Gruendl22,23, P. Guarnieri6, G. Gutierrez3, W. Hartley4, K. Honscheid16,34, B. Jain10, D. J. James1, T. Jeltema56, S. Jouvel2, R. Kessler29, A. King52, D. Kirk2, R. Kron29, K. Kuehn35, N. Kuropatkin3, O. Lahav2,?, T. S. Li25, M. Lima21,37, H. Lin3, M. A. G. Maia21,20, M. Makler54, M. Manera2, C. Maraston6, J. L. Marshall25, P. Martini16,38, R. G. McMahon7,8, P. Melchior5, A. Merson2, C. J. Miller31,24, R. Miquel39,50, J. J. Mohr32,27,26, X. Morice-Atkinson6, K. Naidoo2, E. Neilsen3, R. C. Nichol6, B. Nord3, R. Ogando21,20, F. Ostrovski7,8, A. Palmese2, A. Papadopoulos6,51, H. Peiris2, J. Peoples3, A. A. Plazas30, W. J. Percival6, S. L. Reed7,8, A. K. Romer41, A. Roodman19,11, A. Ross16, E. Rozo62, E. S. Rykoff11,19, I. Sadeh2, M. Sako10, C. S´ anchez50, E. Sanchez33, B. Santiago48, V. Scarpine3, M. Schubnell24, I. Sevilla-Noarbe33,23, E. Sheldon43, M. Smith53, R. C. Smith1, M. Soares- Santos3, F. Sobreira3,21, M. Soumagnac2, E. Suchyta10, M. Sullivan53, M. Swanson63, G. Tarle24, J. Thaler44, D. Thomas6,45, R. C. Thomas40, D. Tucker3, J. D. Vieira23,44,22, V. Vikram36, A. R. Walker1, R. H. Wechsler11,19, W. Wester3, J. Weller32,26,28, L. Whiteway2, H. Wilcox6, B. Yanny3, Y. Zhang24, J. Zuntz18 ? Corresponding author: o.lahav@ucl.ac.uk Accepted 2015 ???. Received 2015 ???; in original form 2015 ??? ABSTRACT This overview article describes the legacy prospect and discovery potential of the Dark En- ergy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterise dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from ‘Science Verification’, and from the first, second and third seasons of observations), what DES can tell us about the solar system, the Milky Way, galaxy evolution, quasars, and other topics. In addition, we show that if the cosmolog- ical model is assumed to be ⇤ + Cold Dark Matter (LCDM) then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the dis- covery of 34 Trans Neptunian Objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed). Key words: surveys – galaxies – Galaxy – quasars – supernovae – minor plantes, asteroids c 2002 RAS arXiv:1601.00329v2 [astro-ph.CO] 26 Jan 2016 Eight Ultra-faint Galaxy Candidates Discovered in Year Two of the Dark Energy Survey A. Drlica-Wagner1,⇤, K. Bechtol2,3,†, E. S. Ryko↵4,5, E. Luque6,7, A. Queiroz6,7, Y.-Y. Mao8,4,5, R. H. Wechsler8,4,5, J. D. Simon9, B. Santiago6,7, B. Yanny1, E. Balbinot10,7, S. Dodelson1,11, A. Fausti Neto7, D. J. James12, T. S. Li13, M. A. G. Maia7,14, J. L. Marshall13, A. Pieres6,7, K. Stringer13, A. R. Walker12, T. M. C. Abbott12, F. B. Abdalla15,16, S. Allam1, A. Benoit-L´ evy15, G. M. Bernstein17, E. Bertin18,19, D. Brooks15, E. Buckley-Geer1, D. L. Burke4,5, A. Carnero Rosell7,14, M. Carrasco Kind20,21, J. Carretero22,23, M. Crocce22, L. N. da Costa7,14, S. Desai24,25, H. T. Diehl1, J. P. Dietrich24,25, P. Doel15, T. F. Eifler17,26, A. E. Evrard27,28, D. A. Finley1, B. Flaugher1, P. Fosalba22, J. Frieman1,11, E. Gaztanaga22, D. W. Gerdes28, D. Gruen29,30, R. A. Gruendl20,21, G. Gutierrez1, K. Honscheid31,32, K. Kuehn33, N. Kuropatkin1, O. Lahav15, P. Martini31,34, R. Miquel35,23, B. Nord1, R. Ogando7,14, A. A. Plazas26, K. Reil5, A. Roodman4,5, M. Sako17, E. Sanchez36, V. Scarpine1, M. Schubnell28, I. Sevilla-Noarbe36,20, R. C. Smith12, M. Soares-Santos1, F. Sobreira1,7, E. Suchyta31,32, M. E. C. Swanson21, G. Tarle28, D. Tucker1, V. Vikram37, W. Wester1, Y. Zhang28, J. Zuntz38 (The DES Collaboration) arXiv:1508.03622v2 [astro-ph.GA] 6 Nov 2015 Draft version February 19, 2016 Preprint typeset using L A TEX style emulateapj v. 5/2/11 A DARK ENERGY CAMERA SEARCH FOR AN OPTICAL COUNTERPART TO THE FIRST ADVANCED LIGO GRAVITATIONAL WAVE EVENT GW150914 M. Soares-Santos1, R. Kessler2, E. Berger3, J. Annis1, D. Brout4, E. Buckley-Geer1, H. Chen2, P. S. Cowperthwaite3, H. T. Diehl1, Z. Doctor2, A. Drlica-Wagner1, B. Farr2, D. A. Finley1, B. Flaugher1, R. J. Foley5,6, J. Frieman1,2, R. A. Gruendl5,7, K. Herner1, D. Holz2, H. Lin1, J. Marriner1, E. Neilsen1, A. Rest8, M. Sako4, D. Scolnic2, F. Sobreira9, A. R. Walker10, W. Wester1, B. Yanny1, T. M. C. Abbott10, F. B. Abdalla11,12, S. Allam1, R. Armstrong13, M. Banerji14,15, A. Benoit-L´ evy16,11,17, R. A. Bernstein18, E. Bertin16,17, D. A. Brown19, D. L. Burke20,21, D. Capozzi22, A. Carnero Rosell23,24, M. Carrasco Kind5,7, J. Carretero25,26, F. J. Castander25, S. B. Cenko27,28, R. Chornock29, M. Crocce25, C. B. D’Andrea22,30, L. N. da Costa23,24, S. Desai31,32, J. P. Dietrich32,31, M. R. Drout3, T. F. Eifler4,33, J. Estrada1, A. E. Evrard34,35, S. Fairhurst36, E. Fernandez26, J. Fischer4, W. Fong37, P. Fosalba25, D. B. Fox38, C. L. Fryer39, J. Garcia-Bellido40, E. Gaztanaga25, D. W. Gerdes35, D. A. Goldstein41,42, D. Gruen20,21, G. Gutierrez1, K. Honscheid43,44, D. J. James10, I. Karliner6, D. Kasen45,46, S. Kent1, N. Kuropatkin1, K. Kuehn47, O. Lahav11, T. S. Li48, M. Lima49,23, M. A. G. Maia23,24, R. Margutti50, P. Martini43,51, T. Matheson52, R. G. McMahon14,15, B. D. Metzger53, C. J. Miller34,35, R. Miquel54,26, J. J. Mohr31,32,55, R. C. Nichol22, B. Nord1, R. Ogando23,24, J. Peoples1, A. A. Plazas33, E. Quataert56, A. K. Romer57, A. Roodman20,21, E. S. Rykoff20,21, E. Sanchez40, V. Scarpine1, R. Schindler21, M. Schubnell35, I. Sevilla-Noarbe40,5, E. Sheldon58, M. Smith30, N. Smith59, R. C. Smith10, A. Stebbins1, P. J. Sutton60, M. E. C. Swanson7, G. Tarle35, J. Thaler6, R. C. Thomas42, D. L. Tucker1, V. Vikram61, R. H. Wechsler62,20,21, J. Weller31,55,63 (The DES Collaboration) Draft version February 19, 2016 ABSTRACT We report initial results of a deep search for an optical counterpart to the gravitational wave event GW150914, the first trigger from the Advanced LIGO gravitational wave detectors. We used the Dark Energy Camera (DECam) to image a 102 deg2 area, corresponding to 38% of the initial trigger high- probability sky region and to 11% of the revised high-probability region. We observed in i and z bands at 4–5, 7, and 24 days after the trigger. The median 5 point-source limiting magnitudes of our search images are i = 22.5 and z = 21.8 mag. We processed the images through a di↵erence-imaging pipeline using templates from pre-existing Dark Energy Survey data and publicly available DECam data. Due to missing template observations and other losses, our e↵ective search area subtends 40 deg2, corresponding to 12% total probability in the initial map and 3% of the final map. In this area, we search for objects that decline significantly between days 4–5 and day 7, and are undetectable by day 24, finding none to typical magnitude limits of i = 21.5,21.1,20.1 for object colors (i z) = 1,0, 1, respectively. Our search demonstrates the feasibility of a dedicated search program with DECam and bodes well for future research in this emerging field. Subject headings: binaries: close — catalogs — gravitational waves — stars: neutron — surveys 1 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA 2 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 4 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 5 Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA 6 Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA 7 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 8 STScI, 3700 San Martin Dr., Baltimore, MD 21218, USA 9 Instituto de F´ ısica Te´ orica, Universidade Estadual Paulista, ley Road, Cambridge CB3 0HA, UK 15 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 16 CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 17 Sorbonne Universit´ es, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 18 Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101, USA 19 Physics Department, Syracuse University, Syracuse, NY 13244 20 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA 21 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 22 Institute of Cosmology & Gravitation, University of arXiv:1602.04198v2 [astro-ph.CO] 18 Feb 2016 Draft version December 11, 2015 Preprint typeset using L ATEX style emulateapj v. 5/2/11 OBSERVATION AND CONFIRMATION OF SIX STRONG LENSING SYSTEMS IN THE DARK ENERGY SURVEY SCIENCE VERIFICATION DATA B. Nord1, E. Buckley-Geer1, H. Lin1, H. T. Diehl1, J. Helsby2, N. Kuropatkin1, A. Amara3, T. Collett4, S. Allam1, G. Caminha5, C. De Bom5, S. Desai6,7, H. D´ umet-Montoya8, M. Elidaiana da S. Pereira5, D. A. Finley1, B. Flaugher1, C. Furlanetto9, H. Gaitsch1, M. Gill10, K. W. Merritt1, A. More11, D. Tucker1, E. S. Rykoff12,10, E. Rozo13, F. B. Abdalla14,15, A. Agnello16, M. Auger17, R. J. Brunner18,19, M. Carrasco Kind18,19, F. J. Castander20, C. E. Cunha12, L. N. da Costa21,22, R. Foley18,23, D. W. Gerdes24, K. Glazebrook25, J. Gschwend21,22, W. Hartley3, R. Kessler2, D. Lagattuta26, G. Lewis27, M. A. G. Maia21,22, M. Makler5, F. Menanteau18,19, A. Niernberg28, D. Scolnic2, J. D. Vieira18,23,19, R. Gramillano18, T. M. C. Abbott29, M. Banerji17,30, A. Benoit-L´ evy31,14,32, D. Brooks14, D. L. Burke12,10, D. Capozzi4, A. Carnero Rosell21,22, J. Carretero20,33, C. B. D’Andrea4,34, J. P. Dietrich6,7, P. Doel14, A. E. Evrard35,24, J. Frieman1,2, E. Gaztanaga20, D. Gruen36,37, K. Honscheid38,39, D. J. James29, K. Kuehn40, T. S. Li41, M. Lima42,21, J. L. Marshall41, P. Martini38,43, P. Melchior38,44,39, R. Miquel45,33, E. Neilsen1, R. C. Nichol4, R. Ogando21,22, A. A. Plazas46, A. K. Romer47, M. Sako48, E. Sanchez49, V. Scarpine1, M. Schubnell24, I. Sevilla-Noarbe49,18, R. C. Smith29, M. Soares-Santos1, F. Sobreira1,21, E. Suchyta48, M. E. C. Swanson19, G. Tarle24, J. Thaler23, A. R. Walker29, W. Wester1, Y. Zhang24 (The DES Collaboration) 1 Fermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510, USA 2 Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA 3 Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich, Switzerland 4 Institute of Cosmology & Gravitation, University of Portsmouth, Portsmouth, PO1 3FX, UK 5 ICRA, Centro Brasileiro de Pesquisas F´ ısicas, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ, Brazil 6 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany 7 Faculty of Physics, Ludwig-Maximilians University, Scheinerstr. 1, 81679 Munich, Germany 8 Universidade Federal do Rio de Janeiro - Campus Maca´ e, Rua Alo´ ısio Gomes da Silva, 50 - Granja dos Cavaleiros, Cep: 27930-560, Maca´ e, RJ, Brazil 9 University of Nottingham, School of Physics and Astronomy, Nottingham NG7 2RD, UK 10 SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA 11 Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan 12 Kavli Institute for Particle Astrophysics & Cosmology, P. O. Box 2450, Stanford University, Stanford, CA 94305, USA 13 Department of Physics, University of Arizona, Tucson, AZ 85721, USA 14 Department of Physics & Astronomy, University College London, Gower Street, London, WC1E 6BT, UK 15 Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown, 6140, South Africa 16 Department of Physics and Astronomy, PAB, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA 17 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 18 Department of Astronomy, University of Illinois, 1002 W. Green Street, Urbana, IL 61801, USA 19 National Center for Supercomputing Applications, 1205 West Clark St., Urbana, IL 61801, USA 20 Institut de Ci` encies de l’Espai, IEEC-CSIC, Campus UAB, Carrer de Can Magrans, s/n, 08193 Bellaterra, Barcelona, Spain 21 Laborat´ orio Interinstitucional de e-Astronomia - LIneA, Rua Gal. Jos´ e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 22 Observat´ orio Nacional, Rua Gal. Jos´ e Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil 23 Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA 24 Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA 25 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, Victoria 3122, Australia 26 Centre de Recherche Astrophysique de Lyon, Universit´ e de Lyon, Universit´ e Lyon 1, CNRS, Observatoire de Lyon; 9 avenue Charles Andr´ e, 69561 Saint-Genis Laval Cedex, France 27 Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, NSW 2006, Australia 28 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus OH 43210, USA 29 Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile 30 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 31 CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 32 Sorbonne Universit´ es, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 33 Institut de F´ ısica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra (Barcelona) Spain 34 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK 35 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA 36 Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, 85748 Garching, Germany 37 Universit¨ ats-Sternwarte, Fakult¨ at f¨ ur Physik, Ludwig-Maximilians Universit¨ at M¨ unchen, Scheinerstr. 1, 81679 M¨ unchen, Germany 38 Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA 39 Department of Physics, The Ohio State University, Columbus, OH 43210, USA 40 Australian Astronomical Observatory, North Ryde, NSW 2113, Australia 41 George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA 42 Departamento de F´ ısica Matem´ atica, Instituto de F´ ısica, Universidade de S˜ ao Paulo, CP 66318, CEP 05314-970, S˜ ao Paulo, SP, Brazil 43 Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA 44 Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544, USA 45 Instituci´ o Catalana de Recerca i Estudis Avan¸ cats, E-08010 Barcelona, Spain 46 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA 47 Department of Physics and Astronomy, Pevensey Building, University of Sussex, Brighton, BN1 9QH, UK 48 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA and 49 Centro de Investigaciones Energ´ eticas, Medioambientales y Tecnol´ ogicas (CIEMAT), Madrid, Spain arXiv:1512.03062v1 [astro-ph.CO] 9 Dec 2015 Other… Intrinsic Alignments
8. • Fath (1914): 1,031 galaxies observed with the 60in Mt.Wilson reflector. Position angles for ~60%, no preferred orientation. • Reynolds / Öpik correspondence (1923) Reynolds claims to have observed a preferred orientation in local galaxies, Öpik highlights the importance of systematic effects. 1920MNRAS..81..129R Early Observations Reynolds 1923
9. Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY
10. Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY
11. Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY DES Collaboration 2015 1507.05552
12. Intrinsic Alignments Light from distant galaxies distorted by gravitational potential of intervening mass. G ravitational – G ravitational Lens ing Light from distant galaxy bent by DM gravitational field. Observed image distorted- Weak Gravitational Lensing C l GG C l = C l GG + C l II + C l GI Donnacha Kirk 11/11/10 Edinburgh Interview 6/22
13. Intrinsic Alignments (Observer’s view on the sky) Lensing by matter causes nearby galaxies to align: Gravitational-Gravitational (GG) Correlation
14. IAs Origin Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Fig. 1.— Left: Sample of simulation particles subsumed into a common halo in an N-body simul identified by a variant of the friends-of-friends algorithm, identifying arbitrarily shaped regions w a certain threshold. Increasing this threshold, the halo is decomposed into a number of sub-halo di↵erent symbols. Right: Representation of the halo and its substructure by ellipsoids which ar eigenvalues and directions of the inertia tensor. The directions of the angular momenta of the well as of the parent halo are given by the arrows. Halo shapes and spins are key ingredients for t galaxy alignments. c AAS. Reproduced with permission from Barnes & Efstathiou (1987). We then review recent work, proceeding from small-scale alignments inside an overdense regi cluster (Section 4), to alignments between clusters and with the cosmic web (Section 5), to ali defined galaxy populations (Section 6). Section 7 summarises the impact of alignments on cosm corresponding mitigation strategies, followed by an outlook on future developments of the field work is part of a topical volume on galaxy alignments consisting of three papers in total. The tw take a more detailed and technical approach, covering theory, modelling, and simulations (Kies • Naive WL assumes that galaxies’ intrinsic shapes are randomly distributed on the sky. • But it has long been suspected that physics of galaxy formation induces correlations in intrinsic shapes. Barnes & Efstathiou 1987
15. IAs Origin Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Fig. 1.— Left: Sample of simulation particles subsumed into a common halo in an N-body simul identified by a variant of the friends-of-friends algorithm, identifying arbitrarily shaped regions w a certain threshold. Increasing this threshold, the halo is decomposed into a number of sub-halo di↵erent symbols. Right: Representation of the halo and its substructure by ellipsoids which ar eigenvalues and directions of the inertia tensor. The directions of the angular momenta of the well as of the parent halo are given by the arrows. Halo shapes and spins are key ingredients for t galaxy alignments. c AAS. Reproduced with permission from Barnes & Efstathiou (1987). We then review recent work, proceeding from small-scale alignments inside an overdense regi cluster (Section 4), to alignments between clusters and with the cosmic web (Section 5), to ali defined galaxy populations (Section 6). Section 7 summarises the impact of alignments on cosm corresponding mitigation strategies, followed by an outlook on future developments of the field work is part of a topical volume on galaxy alignments consisting of three papers in total. The tw take a more detailed and technical approach, covering theory, modelling, and simulations (Kies Barnes & Efstathiou 1987
16. IAs Origin Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Fig. 1.— Left: Sample of simulation particles subsumed into a common halo in an N-body simul identified by a variant of the friends-of-friends algorithm, identifying arbitrarily shaped regions w a certain threshold. Increasing this threshold, the halo is decomposed into a number of sub-halo di↵erent symbols. Right: Representation of the halo and its substructure by ellipsoids which ar eigenvalues and directions of the inertia tensor. The directions of the angular momenta of the well as of the parent halo are given by the arrows. Halo shapes and spins are key ingredients for t galaxy alignments. c AAS. Reproduced with permission from Barnes & Efstathiou (1987). We then review recent work, proceeding from small-scale alignments inside an overdense regi cluster (Section 4), to alignments between clusters and with the cosmic web (Section 5), to ali defined galaxy populations (Section 6). Section 7 summarises the impact of alignments on cosm corresponding mitigation strategies, followed by an outlook on future developments of the field work is part of a topical volume on galaxy alignments consisting of three papers in total. The tw take a more detailed and technical approach, covering theory, modelling, and simulations (Kies Barnes & Efstathiou 1987
17. IAs Origin Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Fig. 1.— Left: Sample of simulation particles subsumed into a common halo in an N-body simul identified by a variant of the friends-of-friends algorithm, identifying arbitrarily shaped regions w a certain threshold. Increasing this threshold, the halo is decomposed into a number of sub-halo di↵erent symbols. Right: Representation of the halo and its substructure by ellipsoids which ar eigenvalues and directions of the inertia tensor. The directions of the angular momenta of the well as of the parent halo are given by the arrows. Halo shapes and spins are key ingredients for t galaxy alignments. c AAS. Reproduced with permission from Barnes & Efstathiou (1987). We then review recent work, proceeding from small-scale alignments inside an overdense regi cluster (Section 4), to alignments between clusters and with the cosmic web (Section 5), to ali defined galaxy populations (Section 6). Section 7 summarises the impact of alignments on cosm corresponding mitigation strategies, followed by an outlook on future developments of the field work is part of a topical volume on galaxy alignments consisting of three papers in total. The tw take a more detailed and technical approach, covering theory, modelling, and simulations (Kies GG II IG Barnes & Efstathiou 1987
18. Intrinsic Alignments Intrinsic (unlensed) galaxy shapes align with local large scale gravitational potential. [Catelan, Kamionkowski & Blandford 2000] G ravitational – G ravitational Lens ing Light from distant galaxy bent by DM gravitational field. Observed image distorted- Weak Gravitational Lensing C l GG C l = C l GG + C l II + C l GI Donnacha Kirk 11/11/10 Edinburgh Interview 6/22
19. Intrinsic Alignments (Observer’s view on the sky) Background galaxies’ intrinsic shapes are aligned: Intrinsic-Intrinsic (II) Correlation
20. Intrinsic Alignments While simultaneously lensing background galaxies à Anti- correlation of shapes. [Hirata & Seljak 2004] G ravitational – G ravitational Lens ing Light from distant galaxy bent by DM gravitational field. Observed image distorted- Weak Gravitational Lensing C l GG C l = C l GG + C l II + C l GI Donnacha Kirk 11/11/10 Edinburgh Interview 6/22 For a sufficiently broad redshift sample, massive structures may cause alignment of foreground galaxies.
21. Intrinsic Alignments (Observer’s view on the sky) Induces an anti-correlation in observed galaxy shapes Gravitational-Intrinsic (GI) Correlation Foreground galaxies aligned with mass. Background galaxies lensed by the same mass.
22. IAs origins Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Projected angular power spectra
23. IAs origins Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Projected angular power spectra
24. IAs origins Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Projected angular power spectra
25. IAs origins DARK ENERGY SURVEY II
26. IAs origins DARK ENERGY SURVEY II GI GG
27. IAs origins DARK ENERGY SURVEY II GI GG
28. IAs origins DARK ENERGY SURVEY II GI GG
29. IAs origins DARK ENERGY SURVEY II GI GG
30. IAs origins DARK ENERGY SURVEY II GI GG
31. IAs origins DARK ENERGY SURVEY II GI GG
32. IAs origins DARK ENERGY SURVEY II GI GG
33. 28 Donnacha Kirk, Alina Kiessling, Benjamin Joachimi Impact on Cosmology • Intrinsic Alignment signal mimics cosmic shear. Kirk et al. 2013
34. 28 Donnacha Kirk, Alina Kiessling, Benjamin Joachimi Impact on Cosmology • Intrinsic Alignment signal mimics cosmic shear. Kirk et al. 2013
35. 28 Donnacha Kirk, Alina Kiessling, Benjamin Joachimi Impact on Cosmology • Intrinsic Alignment signal mimics cosmic shear. imi Kirk et al. 2013
36. IAs as nuisance DARK ENERGY SURVEY Credit: Boris Leisteidt • Intrinsic Alignment signal mimics cosmic shear. • Ignoring IAs will bias inferred cosmology. • Perfect knowledge of IAs would allow direct subtraction (or cosmological explotiation). Unlikely anytime soon.
37. Cosmic Shear Intrinsic Alignments (IA) Effect on cosmic shear of changing w by 1% Normalised to Super-COSMOS Heymans et al 2004
38. If we consider only w then IA bias on w is ~10% If we marginalise 6 cosmological parameters then IA bias on w is ~100% (+/- 1 !) See Bridle & King 2007 for details Intrinsic Alignments (IA) Normalised to Super-COSMOS Heymans et al 2004 Effect on cosmic shear of changing w by 1%
39. IAs as nuisance Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY for details. A0 β η ηz Fid 5.92 1.1 -0.47 0.0 Min 0.0 -5.0 -10.0 -3.0 Max 10.0 5.0 10.0 3.0 biasph σph ∆LFα ∆LFP ∆LFQ ∆LFred α ∆LFred P ∆LFred Q Fid 0.0 0.05 0.0 0.0 0.0 0.0 0.0 0.0 σ (Gaussian Prior) 0.002 0.003 0.05 0.5 0.5 0.1 0.5 0.5 σ (Gaussian Prior) 0.005 0.006 0.05 0.5 0.5 0.1 0.5 0.5 0.22 0.26 0.30 0.82 0.86 0.90 0.60 0.70 0.80 0.90 −2.0 −1.6 −1.2 −0.8 −1.0 0.0 1.0 2.0 0.82 0.86 0.90 0.60 0.70 0.80 0.90 −2.0 −1.6 −1.2 −0.8 0.22 0.26 0.30 −1.0 0.0 1.0 2.0 0.82 0.86 0.90 0.60 0.70 0.80 0.90 −2.0 −1.6 −1.2 −0.8 −1.5 −0.5 0.0 0.5 1.0 LSST no sys LSST HF G impact LSST HF G blue+red impact LSST HF D impact LSST HF G blue+red marg Ωm σ8 h0 w0 wa wa w0 h0 σ8 Prob Krause, Eifler & Blazek 2015 1506.08730
40. Dealing with IAs Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Several options: - Choose a data vector insensitive to IAs e.g. galaxy-galaxy lensing? Shear Peaks? - Nulling - Model, using some nuisance parameters and marginalise.
41. Dealing with IAs Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Several options: - Choose a data vector insensitive to IAs e.g. galaxy-galaxy lensing? Shear Peaks? - Nulling - Model, using some nuisance parameters and marginalise. Model enters here
42. IA Models Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • We believe different physical processes govern alignment of early- and late-type galaxies… Change in protogalaxy’sshape “Tidal Stretching” Elliptical Galaxies Generates Angular Momentum “Tidal Torquing” Disc Galaxies • Tidally Generated Alignments, Gradients of Gravitational force across protogalaxy. A. Linear alignment model mple model for the ellipticities of elliptical galaxies oposed by [26]. The intrinsic shear of the galaxy med to follow the linear relation γI = − C1 4πG (∇2 x − ∇2 y , 2∇x∇y)S[ΨP ], (13) where fE(w) = (w2 x − spectrum, we replace PBB ˜ γI (k) = C1 ¯ D ×f
43. CFHTLenSSplit by colour C. Heymans et al. re 11. Joint parameter constraints on the amplitude of the intrinsic alignment model A and the matter density parameter ⌦ m from CFHTLenS WMAP7, BOSS and R11. In the left panel the constraints can be compared between two galaxy samples split by SED type, (early-type in red an ue). In the right panel we present constraints from a optimised analysis to enhance the measurement of the intrinsic alignment amplitude of xies (pink). The full sample, combining early and late-type galaxies, produces an intrinsic alignment signal that is consistent with zero (shown IA Models DARK ENERGY SURVEY • Marginal detection of IA signal in early-type galaxies. • Late-type galaxies consistent with zero. Heymans et al. 2013 1303.1808
44. Dealing with IAs Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Comparison of three IA models. • No significant impact with the large errors on DES SV data. • No attempt to split the data by colour. • Much more exciting things to come with Y1 data! DES Collaboration 2015 1507.05552
45. Dealing with IAs Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Comparison of three IA models. • No significant impact with the large errors on DES SV data. • No attempt to split the data by colour. • Much more exciting things to come with Y1 data! DES Collaboration 2015 1507.05552 ower spectra, PII and PGI. Within the tidal alignment paradigm of IAs (see Troxe & Ishak (2014); Joachimi et al. (2015b); Kiessling et al 2015); Kirk et al. (2015b) for general reviews of IAs), the eading-order correlations define the linear alignment (LA) model (Hirata & Seljak 2010). In the LA model predictions or the II and GI terms give PII(k, z) = F2(z)P (k, z), PGI(k, z) = F(z)P (k, z), (A5) where F(z) = AC1 ⇢crit ⌦m D(z) . (A6) crit is the critical density at z = 0, C1 = 5 ⇥ 0 14h 2M 1Mpc3 is a normalisation amplitude (Hambly order correlations define the linear alignment (LA) Hirata & Seljak 2010). In the LA model predictions I and GI terms give z) = F2(z)P (k, z), PGI(k, z) = F(z)P (k, z), (A5) F(z) = AC1 ⇢crit ⌦m D(z) . (A6) the critical density at z = 0, C1 = 5 ⇥ 2M 1Mpc3 is a normalisation amplitude (Hambly 01; Brown et al. 2003; Bridle & King 2007), and
46. Effect of Nuisance Parameters Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit
47. Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit Effect of Nuisance Parameters
48. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • ‘Self’-calibration. not correlated with any of the other measures and only yiel contribution to the noise, see Sect. 3.4. Inserting (1) and (2) into (3), one obtains the complete of tomographic two-point observables which are available fr shape and number density information C(i j) ϵϵ (ℓ) = C(i j) GG (ℓ) + C(i j) IG (ℓ) + C(ji) IG (ℓ) + C(i j) II (ℓ) C(i j) nn (ℓ) = C(i j) gg (ℓ) + C(i j) gm (ℓ) + C(ji) gm (ℓ) + C(i j) mm (ℓ) C(i j) nϵ (ℓ) = C(i j) gG (ℓ) + C(i j) gI (ℓ) + C(i j) mG (ℓ) + C(i j) mI (ℓ) , see Bernstein (2009). We name signals stemming from gala shape information by capital letters (‘G’ for gravitational she ‘I’ for intrinsic shear) and signals related to galaxy number d sities by small letters (‘g’ for intrinsic number density fluct tions, ‘m’ for lensing magnification). An overview of the nom clature of the correlations in (4) to (6) is provided in Table Note that (4) and (5) are symmetric with respect to their pho z bin arguments. Hence, if Nzbin denotes the number of ava • Use additional information to learn about your nuisance parameters. • Extra observables sensitive to IAs but with different redshift/cosmology dependences.
49. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • ‘Self’-calibration. not correlated with any of the other measures and only yiel contribution to the noise, see Sect. 3.4. Inserting (1) and (2) into (3), one obtains the complete of tomographic two-point observables which are available fr shape and number density information C(i j) ϵϵ (ℓ) = C(i j) GG (ℓ) + C(i j) IG (ℓ) + C(ji) IG (ℓ) + C(i j) II (ℓ) C(i j) nn (ℓ) = C(i j) gg (ℓ) + C(i j) gm (ℓ) + C(ji) gm (ℓ) + C(i j) mm (ℓ) C(i j) nϵ (ℓ) = C(i j) gG (ℓ) + C(i j) gI (ℓ) + C(i j) mG (ℓ) + C(i j) mI (ℓ) , see Bernstein (2009). We name signals stemming from gala shape information by capital letters (‘G’ for gravitational she ‘I’ for intrinsic shear) and signals related to galaxy number d sities by small letters (‘g’ for intrinsic number density fluct tions, ‘m’ for lensing magnification). An overview of the nom clature of the correlations in (4) to (6) is provided in Table Note that (4) and (5) are symmetric with respect to their pho z bin arguments. Hence, if Nzbin denotes the number of ava • Use additional information to learn about your nuisance parameters. • Extra observables sensitive to IAs but with different redshift/cosmology dependences.
50. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit
51. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit
52. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY smological Impact of Intrinsic Alignment Model Choice 7 1.5 2 t IA model in fit As in fit w 0 w a εε, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε+nε+nn, no felxibility in IA model −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 w 0 w a εε + nε+nn, marginalised over IA grid −3 −2 −1 0 −2 0 2 4 6 8 Latest IA model in data; latest IA model in fit Latest IA model in data; HS04NL in fit
53. Cross-correlations Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Part of our plans for DES Y1 analysis
54. WL x CMB-WL Overlap with the South Pole Telescope Survey (SPT) • WL from two totally different sources on the same patch of sky. • Sensitive to the same matter distribution (at low redshift). • CMB-WL is insensitive to IAs. — COSMOLOGY WITH GALAXY -CMB LENSING CROSS-CORRELATIONS Yuuki Omori SOUTH POLE TELESCOPE (SPT) South pole Telescope 10m SPT SZ survey (2008-2011) Tri-band (90,150,220 GHz) Footprint 2500deg2 ! Moving on to SPT-3G soon !13 DATA: SOUTH POLE TELESCOPE
55. CMB Lensing • Deflection angles ~2.5arcmin [Blanchard & Schneider 87, Coles & Efstathiou 89, Lewis & Challinor 06] • Lensing: convolution, mixes modes. • Effects on CMB temperature: blur peaks [Seljak 96], extra small scale power (leak from large scales) [Linder 90] • Polarisation: also E to B leak [Zaldarriaga & Seljak 98] • Creates non-Gaussianities [Bernardeau 97] • Nuisance and Opportunity. CMB lensing • CMB lensing: deflection angles ~2.5 arc min [Blanchard & Schneider 87, Coles & Efstathiou 89, Lewis & Challinor 06] • Lensing: convolution, mixes modes • Effects on CMB temperature: blur peaks [Seljak 96] , extra small-scale power (leak from large scales) [Linder 90] • Polarisation: also E to B leak [Zaldarriaga & Seljak 98] • Creates non-Gaussianities [Bernardeau 97] Lensed Unlensed 2.5º Cdd ⇧ [ˆ n] = ˜[ˆ n + d] [ˆ n] = ˜[ˆ n + ⇧⇧(ˆ n)] d = ⇧⇧ + ⇧ ⇥ ⌥ 3 Photons from last scattering surface deflected by gravitational potential of large-scale structure Nuisance & opportunity [W. Hu] Temperature power spectrum multipole l Nuisance & Opportunity
56. !15 — FOOTPRINT SPT OVERLAP DES SV DATA: DARK ENERGY SURVEY
57. Weak Lensing x CMB Lensing Cross-correlation — !10 — GALAXY LENSING - CMB LENSING CROSS-CORRELATION kernels matter power spectrum BACKGROUND
58. CROSS-CORRELATION Measurement of the Cross-correlation Redshift Range 0 . 3 < z < 1 . 3 CMB E A 2/ d.o.f. ngmix ⇥ SPT 0 . 88+0.30 0.30 0.93 ngmix ⇥ Planck 0 . 86+0.39 0.39 1.52 • Angular power spectrum Cl using PolSpice harmonic space estimator. Fix cosmology, use theory prediction to fit cross-correlation amplitude. • Evidence for cross-correlation at the 3 sigma level. • DES x SPT and DES x Planck are consistent. • Measured cross-correlation is consistent with the expectation from theory using Planck 2015 cosmology.
59. 10 8 10 7 10 6 10 5 CMB E |CMB I | CMB E + CMB I 0 200 400 600 800 1000 1200 1400 1600 0 5 10 15 20 `CX(`) IA% ` CMB ⇥ X 0.3 < z < 1.3 Intrinsic Alignments • Use simple non-linear alignment model to estimate the order of magnitude impact on our measurement. • Effect ~20% of expected amplitude. Assume no IAs: A=0.88±0.30 Assume NLA model: A=1.08±0.36
60. IAs and the Cosmic Web Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY • Intrinsic alignments are thought to align with cosmic web structures – clusters, filaments, voids. • Could be a window onto galaxy formation and evolution of structure. Hz-AGN intrinsic alignments 9 Figure 9. Cross-correlations of galaxy positions and shapes (ηe) or spins (ηs) for the galaxy population divided in two V/σ bins. δ indicates tracers of the galaxy density field and s (m) indicates the sample for which the orientation is measured from the spin (minor axis). The black solid line shows the correlation between the positions of disc-like tracers of the density field (V/σ > 0.55) and the direction of the minor axis of the reduced inertia tensor of spheroidal galaxies (V/σ < 0.55). The red solid line shows the correlation between the positions of spheroidal galaxies and the direction of the minor axis of disc-like galaxies. The red dotted line shows the correlation between the position of discs and the spin of spheroidals, and the red line shows the correlation between the positions of spheroidals and the direction of the spin axis of discs. (Notice that the red lines almost overlap, showing that the spin and the minor axis of a disc point along the same direction.) These results suggest that the discs are preferentially clustered in the direction of the elongation of spheroidals, while they also tend to have their spins aligned in the direction of nearby spheroidals. Figure 10. A cartoon picture of alignments, as interpreted from the results of Section 5.1. Discs live in filaments connecting el- lipticals and they tend to align their spin(s)/minor axes in the direction of the filament. Ellipticals tend to have their shapes (m represents the minor axis) aligned towards each other and to- wards the direction of the filaments. The effect of alignments is exaggerated for visual purposes by showing all galaxies perfectly aligned following the measured trends in the simulation. icance decreases to 92% when the simple inertia tensor is adopted to measure the shapes. On the contrary, the direc- tion of the spin of spheroidals is not correlated with the po- sition of discs (72% C.L. for null hypothesis rejection of the blue curves), but the minor axis direction of a spheroidal is anti-correlated with the position of discs with high sig- nificance (> 99.99% C.L. for both the reduced ans simple inertia tensor). Finally, we consider whether alignment sig- nals are still present when the orientation is defined by the direction of the major axis. We find that the disc alignment measurement in this case is more sensitive to the choice of reduced/simple inertia tensor. This result confirms that the simple inertia tensor is a worse tracer of the spin compared ig. 2.— Gas density tracing the cosmic web in a subvolume (25 Mpc/h depth, 12.5 Mpc/h width) of the HORIZON- AGN simulation used in Codis et al. (2014). The arrows indicate the direction of the smallest eigenvector of the ravitational tidal tensor (given by the Hessian of the gravitational potential at that point), which is expected to align with filamentary structures (see e.g. the top left corner). Reproduced with permission from Codis et al. (2014). models also predict that these density fluctuations are well described by a Gaussian random field. The fluctuation rength is almost scale-invariant, meaning that there are identical amounts of fluctuation in the density field in each wavelength-interval. Once pressure-less matter dominates the expansion history, density fluctuations within the horizon (i.e. in regions n causal contact which can physically interact) grow via gravitational interaction, initially by processes that are well nderstood in linear perturbation theory. Eventually, over-densities begin to evolve non-linearly and collapse into a alo, an approximately stable state in which the random motions of the constituent particles or objects balance gravity. tructures continue to grow in a bottom-up scenario, i.e. small haloes form first and then coalesce into ever larger aloes. Dark matter haloes have a near-universal radial density distribution (Navarro et al. 1997), and their abundance or a given mass can be estimated analytically (Press & Schechter 1974). Interpreted as quasi-stable bodies with only ttle exchange of matter with their surrounding, haloes can be assigned an angular momentum vector and a shape, ften approximated by an ellipsoid which is determined by the eigenvalues and -vectors of the inertia tensor (see igure 1). These quantities, which are believed to be central to alignment processes, depend strongly on how a halo is efined. N-body simulations illustrate in an impressive manner how the initially Gaussian density fluctuations evolve under ravity into the cosmic web, a network of overdense filaments which intersect at massive haloes. The filaments are n turn embedded into medium-density walls or sheets which surround large, nearly empty regions of space called oids. The general direction of gravitational acceleration will cause matter to flow away from the centres of voids onto heets, in the plane of sheets towards filaments, and along filaments into the massive haloes at the nodes (possibly
61. Fig. 11.— Sketch of galaxy alignments at the surface of a void (shown in green). Elliptical Environment-dependent • Text Fig. 6.— Sketch of satellite galaxy alignments in galaxy groups/clusters. Satellite galaxies (red el as preferentially pointing their major axes towards the centre of the cluster whose shape (and or using a green ellipsoid. BJ: Need a big, red, slightly misaligned galaxy in the centre. 4.2. Alignment of satellite galaxy shapes The alignment of satellite shapes, on the other hand, has a more complicated history (see S because of the di culty of measuring the shapes of small satellite galaxies which are additiona contaminated by light from neighbouring galaxies, in particular in the dense environments of Early SDSS studies (which had orders of magnitude more galaxies, and much better data qualit surements) suggested that satellites in clusters aligned radially toward their central galaxies (P Faltenbacher et al. 2007), but Hao et al. (2011) demonstrated that this was due to systematic e↵ contamination of shape measurements by light from neighbouring galaxies. Subsequently, th have found that satellite galaxies in groups and clusters are consistent with being randomly ori of galaxy alignments with a filament (shown in green). Elliptical galaxies (red ellipsoids) tend to xes with the filament direction, while disc galaxies (blue discs) tend to align their spin perpendicular of the gravitational lensing signal and its intrinsic alignment contamination. The matter structure deflects the light from the background source galaxies (blue discs) and distorts their images tangen- t to the apparent centre of the lens (as seen in the bottom plane). As a consequence, the galaxy igned (GG signal). Galaxies which are physically close to the lens structure (red ellipsoids) may be s that cause them to point towards the structure, which results in the alignment of their images (II galaxies close to the lens are then preferentially anti-aligned with the gravitationally sheared images axies (GI signal). standard technical introduction to weak lensing is given in Bartelmann & Schneider (2001). Bartel- ided an overview on the whole theme of gravitational lensing, while more specialised reviews are hi et al. (2008) and Hoekstra & Jain (2008) on cosmological applications of weak lensing, in Massey e study of dark matter particularly via weak lensing, and in Kilbinger (2014) on recent progress in he large-scale structure. al deflection of light is accurately described in the framework of general relativity and served as the Observations are Messy
62. CFHTLenS: Testing the Laws of Gravity 9 Figure 5. Left: Constraints on the modified gravity parameters in a flat ⇤CDM background from redshift space distortions (green), weak lensing (red), and combined (blue). (68 and 95 per cent CL). The dashed and solid contours represent the 68 and 95 per cent condence intervals respectively. Two auxiliary datasets are used here to break degeneracies with the conventional cosmological parameters. These are the small-angle anisotropies from WMAP7 (` > 100), and a prior on H 0 from (Riess et al. 2011). The cross positioned at the origin denotes the prediction of General Relativity. Right: The red, green and blue contours are the same as the left panel, except the prior on H 0 has been replaced by measurements of the Baryon Acoustic Oscillations as detailed in Section 3.2. The yellow contours signify the constraints derived from the full WMAP7 power spectra, including the large angular scales (` < 100). The white contours in the left hand panel show the constraints when all data sets are analysed in combination. Table 1. Parameter constraints for different combinations of dataset and parameter space. The three different backgrounds we explore are flat ⇤CDM, flat wCDM and the non-flat wCDM which we denote as owCDM. All constraints make use of the small scale anisotropies from WMAP7 (` > 100), while those marked ISW also utilise the larger angular scales. Background Data (+ CMB + H0) µ0 ⌃0 ⌦m H0 8 w ⌦K The Future: IAs as a probe of gravity? DARK ENERGY SURVEY • Cosmic shear uses the bending of light- sensitive to the sum of the metric potentials. • Intrinsic Alignments are a local effect sensitive to galaxy formation – sensitive to the Newtonian potential. • In the future it might be possible to use the IA part of the observed cosmic shear signal to test gravity on cosmic scales. Light sensitive to + n n Non-relativistic matter (galaxies) sensitive to Simpson et al. 2012, CFHTLenS 1212.3339 tial experienced by n tential ( + ) experie ulated by the parameter (k, a) = [ (k, a) + (k, a)] = where we have adopted (2008), as used more tential ( + ) experie ulated by the parameter (k, a) [ (k, a) + (k, a)] = where we have adopted (2008), as used more et al. (2011). This para ing the modified behav by µ(k, a), from modi by ⌃(k, a). By being a ( [ (k, a) + (k, where we have ad (2008), as used et al. (2011). Thi ing the modified by µ(k, a), from by ⌃(k, a). By b tional outcomes, tion functions and
63. Galaxy Alignments Overlap with the South Pole Telescope Survey (SPT) DARK ENERGY SURVEY Modelling: Linear theory Quasi- and non- linear scales, Sub-halo scales, Halo model, Perturbation theory, Gravity Observations: Position alignment, Shape Alignment, Spin Alignment, CMB, Large volumes, Shape Measurement, Redshift Discrimination, Environment determination. Simulations: N-body high-res. Semi-analytic models Hydro with realistic physics. Galaxy Formation & Evolution Weak Lensing Tidal Alignment vs. Baryon Physics. Dark Energy Survey DARK ENERGY SURVEY