Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

¹ LIGO - California Institute of Technology, Pasadena, CA 91125, USA
² California State University Fullerton, Fullerton CA 92831, USA
³ SUPA, University of Glasgow, Glasgow, G12 8QQ, UK
⁴ Laboratoire d’Annecy-le-Vieux de Physique des Particules (LAPP), Université de Savoie, CNRS/IN2P3, 74941 Annecy-Le-Vieux, France
⁵ INFN, Sezione di Napoli, Complesso Universitario di Monte S.Angelo, 80126 Napoli, Italy
⁶ Università di Napoli “Federico II”, Complesso Universitario di Monte S.Angelo, 80126 Napoli, Italy
⁷ Università di Salerno, Fisciano, 84084 Salerno, Italy
⁸ LIGO - Livingston Observatory, Livingston, LA 70754, USA
⁹ Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, 30167 Hannover, Germany
¹⁰ Leibniz Universität Hannover, 30167 Hannover, Germany
¹¹ Nikhef, Science Park, Amsterdam, The Netherlands
¹² VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
¹³ University of Wisconsin–Milwaukee, Milwaukee, WI 53201, USA
¹⁴ Stanford University, Stanford, CA 94305, USA
¹⁵ University of Florida, Gainesville, FL 32611, USA
¹⁶ Louisiana State University, Baton Rouge, LA 70803, USA
¹⁷ University of Birmingham, Birmingham, B15 2TT, UK
¹⁸ INFN, Sezione di Roma, 00185 Roma, Italy
¹⁹ Università “La Sapienza”, 00185 Roma, Italy
²⁰ LIGO - Hanford Observatory, Richland, WA 99352, USA
²¹ Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, 14476 Golm, Germany
²² Montana State University, Bozeman, MT 59717, USA
²³ European Gravitational Observatory (EGO), 56021 Cascina ( PI), Italy
²⁴ Syracuse University, Syracuse, NY 13244, USA
²⁵ University of Western Australia, Crawley, WA 6009, Australia
²⁶ LIGO - Massachusetts Institute of Technology, Cambridge, MA 02139, USA
²⁷ APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
²⁸ Columbia University, New York, NY 10027, USA
²⁹ INFN, Sezione di Pisa, 56127 Pisa, Italy
³⁰ Università di Pisa, 56127 Pisa, Italy
³¹ Università di Siena, 53100 Siena, Italy
³² The University of Texas at Brownsville, Brownsville, TX 78520, USA
³³ San Jose State University, San Jose, CA 95192, USA
³⁴ Moscow State University, Moscow 119992, Russia
³⁵ LAL, Université Paris-Sud, IN2P3/CNRS, F-91898 Orsay, France
³⁶ ESPCI, CNRS, 75005 Paris, France
³⁷ NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
³⁸ The Pennsylvania State University, University Park, PA 16802, USA
³⁹ Université Nice-Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France
⁴⁰ Institut de Physique de Rennes, CNRS, Université de Rennes 1, 35042 Rennes, France
⁴¹ Laboratoire des Matériaux Avancés (LMA), IN2P3/CNRS, 69622 Villeurbanne, Lyon, France
⁴² Washington State University, Pullman, WA 99164, USA
⁴³ INFN, Sezione di Perugia, 06123 Perugia, Italy
⁴⁴ Università di Perugia, 06123 Perugia, Italy
⁴⁵ INFN, Sezione di Firenze, 50019 Sesto Fiorentino, Italy
⁴⁶ Università degli Studi di Urbino “Carlo Bo”, 61029 Urbino, Italy
⁴⁷ University of Oregon, Eugene, OR 97403, USA
⁴⁸ Laboratoire Kastler Brossel, ENS, CNRS, UPMC, Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France
⁴⁹ Rutherford Appleton Laboratory, HSIC, Chilton, Didcot, Oxon OX11 0QX, UK
⁵⁰ IM-PAN 00-956 Warsaw, Poland
⁵¹ Astronomical Observatory Warsaw University 00-478 Warsaw, Poland
⁵² CAMK-PAN 00-716 Warsaw, Poland
⁵³ Białystok University 15-424 Białystok, Poland
⁵⁴ NCBJ 05-400 Świerk-Otwock, Poland
⁵⁵ Institute of Astronomy 65-265 Zielona Góra, Poland
⁵⁶ University of Maryland, College Park, MD 20742 USA
⁵⁷ Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
⁵⁸ University of Massachusetts - Amherst, Amherst, MA 01003, USA
⁵⁹ Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H8, Canada
⁶⁰ Tsinghua University, Beijing 100084, PR China
⁶¹ University of Michigan, Ann Arbor, MI 48109, USA
⁶² The University of Mississippi, University, MS 38677, USA
⁶³ Charles Sturt University, Wagga Wagga, NSW 2678, Australia
⁶⁴ Caltech-CaRT, Pasadena, CA 91125, USA
⁶⁵ INFN, Sezione di Genova ; 16146 Genova, Italy
⁶⁶ Pusan National University, Busan 609-735, Korea
⁶⁷ Carleton College, Northfield, MN 55057, USA
⁶⁸ Australian National University, Canberra, ACT 0200, Australia
⁶⁹ The University of Melbourne, Parkville, VIC 3010, Australia
⁷⁰ Cardiff University, Cardiff, CF24 3AA, UK
⁷¹ INFN, Sezione di Roma Tor Vergata, 00133 Roma, Italy
⁷² Università di Roma Tor Vergata, 00133 Roma, Italy
⁷³ Università dell’Aquila, 67100 L’ Aquila, Italy
⁷⁴ University of Salerno, 84084 Fisciano (Salerno), Italy and INFN (Sezione di Napoli), Italy
⁷⁵ The University of Sheffield, Sheffield S10 2TN, UK
⁷⁶ WIGNER RCP, RMKI, H-1121 Budapest, Konkoly Thege Miklós út 29-33, Hungary
⁷⁷ INFN, Gruppo Collegato di Trento, 38050 Povo,Trento, Italy
⁷⁸ Università di Trento, 38050 Povo, Trento, Italy
⁷⁹ INFN, Sezione di Padova, 35131 Padova, Italy
⁸⁰ Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India
⁸¹ University of Minnesota, Minneapolis, MN 55455, USA
⁸² California Institute of Technology, Pasadena, CA 91125, USA
⁸³ Northwestern University, Evanston, IL 60208, USA
⁸⁴ The University of Texas at Austin, Austin, TX 78712, USA
⁸⁵ Rochester Institute of Technology, Rochester, NY 14623, USA
⁸⁶ Eötvös Loránd University, Budapest, 1117 Hungary
⁸⁷ University of Adelaide, Adelaide, SA 5005, Australia
⁸⁸ University of Szeged, 6720 Szeged, Dóm tér 9, Hungary
⁸⁹ Embry-Riddle Aeronautical University, Prescott, AZ 86301 USA
⁹⁰ National Institute for Mathematical Sciences, Daejeon 305-390, Korea
⁹¹ Perimeter Institute for Theoretical Physics, Ontario, N2L 2Y5, Canada
⁹² National Astronomical Observatory of Japan, Tokyo 181-8588, Japan
⁹³ Korea Institute of Science and Technology Information, Daejeon 305-806, Korea
⁹⁴ University of Southampton, Southampton, SO17 1BJ, UK
⁹⁵ Institute of Applied Physics, Nizhny Novgorod, 603950, Russia
⁹⁶ Lund Observatory, Box 43, SE-221 00, Lund, Sweden
⁹⁷ Hanyang University, Seoul 133-791, Korea
⁹⁸ Seoul National University, Seoul 151-742, Korea
⁹⁹ University of Strathclyde, Glasgow, G1 1XQ, UK
¹⁰⁰ Southern University and A&M College, Baton Rouge, LA 70813, USA
¹⁰¹ University of Rochester, Rochester, NY 14627, USA
¹⁰² Hobart and William Smith Colleges, Geneva, NY 14456, USA
¹⁰³ University of Sannio at Benevento, 82100 Benevento, Italy and INFN (Sezione di Napoli), Italy
¹⁰⁴ Louisiana Tech University, Ruston, LA 71272, USA
¹⁰⁵ McNeese State University, Lake Charles, LA 70609 USA
¹⁰⁶ University of Washington, Seattle, WA, 98195-4290, USA
¹⁰⁷ Andrews University, Berrien Springs, MI 49104 USA
¹⁰⁸ Trinity University, San Antonio, TX 78212, USA
¹⁰⁹ Southeastern Louisiana University, Hammond, LA 70402, USA
¹¹⁰ Institut de Recherche en Astrophysique et Planetologie (IRAP), 14 Avenue Edouard Belin, 31400 Toulouse, France
¹¹¹ NASA Einstein Fellow  
¹¹² “Pi of the Sky” and the Andrzej Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw, Poland
¹¹³ Jodrell Bank Center for Astrophysics, University of Manchester  
¹¹⁴ Liverpool John Moores University, Liverpool L3 2AJ, UK
¹¹⁵ Astronomical Institute “Anton Pannekoek”, University of Amsterdam, 1090 GE Amsterdam, The Netherlands

Received: 6 October 2011
Accepted: 22 December 2011

Abstract

Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations.

Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline’s ability to reconstruct source positions correctly.

Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with  ~50% or better probability with a few pointings of wide-field telescopes.