Time at &10 GHz with the Square Kilometre Array

Eric J. Murphy1, Mark T. Sargent2∗, Rob J. Beswick3, Clive Dickinson3, Ian Heywood4,5, Leslie K. Hunt6, Minh T. Hyunh7, Matt Jarvis8,9, Alexander Karim10, Marita Krause11, Isabella Prandoni12, Nicholas Seymour13, Eva Schinnerer14, Fatemeh S. Tabatabaei14, Jeff Wagg15 1IPAC, Caltech, MC 220-6, Pasadena CA, 91125, USA; 2Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9 QH, UK; 3Jodrell Bank Centre for Astrophysics, The University of Manchester, Oxford Rd, Man chester M13 9PL, UK; 4CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW 1710, Aus tralia; 5RATT, Department of Physics and Electronics, Rhodes University, PO Box 94, Grah amstown 6140, South Africa; 6INAF Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy; 7ICRAR, University of Western Australia, Stirling Highway, Crawle y, Western Australia 6009, Australia; 8Astrophysics, University of Oxford, Denys Wilkinson Build ing, Keble Road, Oxford, OX1 3RH, UK; 9Department of Physics, University of the Western Cape, Bell vill 7535, South Africa; 10Argelander-Institut für Astronomie, Auf dem Hügel 71, 5312 1 Bonn, Germany; 11Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69 , 53121 Bonn, Germany; 12INAF Istituto di Radioastronomia, Via Gobetti 101, Bologna, Ita ly; 13CASS, P.O. Box 76, Epping, NSW, 1710, Australia; 14Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany;15Square Kilometre Array Organisation, Lower Withington, Ch es ire, UK Email: emurphy@ipac.caltech.edu In this chapter, we highlight a number of science investigat ions that are enabled by the inclusion of Band 5 (4.6−13.8GHz) for SKA1-MID science operations, while focusing on th e astrophysics of star formation over cosmic time. For studying the detailed a strophysics of star formation at highredshift, surveys at frequencies &10 GHz have the distinct advantage over traditional ∼1.4 GHz surveys as they are able to yield higher angular resolution i mag ng while probing higher rest frame frequencies of galaxies with increasing redshift, where em ission of star-forming galaxies becomes dominated by thermal (free-free) radiation. In doing so, su rveys carried out at &10 GHz provide a robust, dust-unbiased measurement of the massive star for mati n rate by being highly sensitive to the number of ionizing photons that are produced. To acces s thi powerful star formation rate diagnostic requires that Band 5 be available for SKA1-MID. W e additionally present a detailed science case for frequency coverage extending up to 30 GHz du ring f ll SKA2 operations, as this allows for highly diverse science while additionally provi ding contiguous frequency coverage between the SKA and ALMA, which will likely be the two most pow erful interferometers for the coming decades. To enable this synergy, it is crucial that th e dish design of the SKA be flexible enough to include the possibility of being fit with receivers operating up to 30 GHz. Advancing Astrophysics with the Square Kilometre Array June 8-13, 2014 Giardini Naxos, Italy