302 research outputs found
Investigating the Source of Planck-Detected AME: High-Resolution Observations at 15 GHz
No full textThe Planck 28.5 GHz maps were searched for potential Anomalous Microwave Emission (AME) regions on the scale of ~3° or smaller, and several new regions of interest were selected. Ancillary data at both lower and higher frequencies were used to construct spectral energy distributions (SEDs), which seem to confirm an excess consistent with spinning dust models. Here we present higher resolution observations of two of these new regions with the Arcminute Microkelvin Imager Small Array (AMI SA) between 14 and 18 GHz to test for the presence of a compact (~10 arcmin or smaller) component. For AME-G107.1+5.2, dominated by the Hii region S140, we find evidence for the characteristic rising spectrum associated with either the spinning dust mechanism for AME or an ultra- /hypercompact Hii region across the AMI frequency band; however, for AME-G173.6+208 we find no evidence for AME on scales of ~2–10 arcmin
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Blind and pointed Sunyaev-Zel'dovich observations with the Arcminute Microkelvin Imager
No full textIn this thesis I discuss my work on the Arcminute Microkelvin Imager (AMI). I focus on the detection of Sunyaev-Zel’dovich (SZ) signatures at 14-18GHz.
Once the background science and operation of the instrument are described I proceed to present my contribution to the calibration of AMI, including: primary beam measurements; refinements to the known antenna geometry and flagging geostationary satellite interference. This is followed by an outline of the software that I have developed to subtract sources from visibilities, concatenate data from multiple observations, simulate data, and perform jack-knife tests to evaluate the magnitude of systematic errors.
The Bayesian analysis that I use to obtain parameter estimates and to quantify the significance of putative SZ detections is described. I perform realistic simulations of clusters and use these to characterise
the analysis. I then, for the first time, apply the analysis to data from the AMI blind cluster survey. I identify several previously unknown
SZ decrements.
Finally, I conduct pointed observations towards a high luminosity subsample of eight clusters from the Local Cluster Substructure Survey
(LoCuSS). For each of these I provide probability distributions of parameters such as mass, radius, and temperature. I compare my
results to those in the literature and find an overall agreement
Aperture Array Configurations for SKA1 Core
No full textThis memo considers some aspects of the configuration of the SKA1 Low Frequency Aperture Array, both at the element and station level. At the element level I propose a possible scenario for form-ing station beams where elements are shared between stations an
Signal and Data Transport for the SKA
No full textThe SKA will be a transformative radio telescope that will address fundamental unanswered questions about our Universe. The SKA will require high precision timing and will then generate unprecedented volumes of data. The Signal and Data Transport (SADT) Consortium has design the systems that address these requirements. I will discuss the design work undertaken by the SADT Consortium to address these challenges through three separate networks:
• A network to transport the astronomical data (tens of Terabits per second), first from the receivers to a Central Signal Processor and then secondly transport the resultant data out of the telescope site to the Science Data Processor
• A clock ensemble that provides a high accuracy timescale that can be tied to global UTC and a network that then distributes a reference frequency and absolute time to each antenna
• A network that passes control, monitor and service data throughout the telescope
Future Science Prospects for AMI
No full textAuthors:- Keith Grainge, Paul Alexander, Richard Battye, Mark Birkinshaw, Andrew Blain, Malcolm Bremer, Sarah Bridle, Michael Brown, Richard Davis, Clive Dickinson, Alastair Edge, George Efstathiou, Robert Fender, Martin Hardcastle, Jennifer Hatchell, Michael Hobson, Matthew Jarvis, Benjamin Maughan, Ian McHardy, Matthew Middleton, Anthony Lasenby, Richard Saunders, Giorgio Savini, Anna Scaife, Graham Smith, Mark Thompson, Glenn White, Kris Zarb-Adami, James Allison, Jane Buckle, Alberto Castro-Tirado, Maria Chernyakova, Roger Deane, Farhan Feroz, Ricardo Genova Santos, David Green, Diana Hannikainen, Ian Heywood, Natasha Hurley-Walker, Ruediger Kneissl, Karri Koljonen, Shrinivas Kulkarni, Sera Markoff, Carrie MacTavish, Michael McCollough, Simone Migliari, Jon M. Miller, James Miller-Jones, Malak Olamaie, Zsolt Paragi, Timothy Pearson, Guy Pooley, Katja Pottschmidt, Rafael Rebolo, John Richer, Julia Riley, Jerome Rodriguez, Carmen Rodriguez-Gonzalvez, Anthony Rushton, Petri Savolainen, Paul Scott, Timothy Shimwell, Marco Tavani, John Tomsick, Valeriu Tudose, Kurt van der Heyden, Alexander van der Horst, Angelo Varlotta, Elizabeth Waldram, Joern Wilms, Andrzej Zdziarski, Jonathan Zwart, Yvette Perrott, Clare Rumsey, Michel SchammelThe Arcminute Microkelvin Imager (AMI) is a telescope specifically designed for high sensitivity measurements of low-surface-brightness features at cm-wavelength and has unique, important capabilities. It consists of two interferometer arrays operating over 13.5-18 GHz that image structures on scales of 0.5-10 arcmin with very low systematics. The Small Array (AMI-SA; ten 3.7-m antennas) couples very well to Sunyaev-Zel'dovich features from galaxy clusters and to many Galactic features. The Large Array (AMI-LA; eight 13-m antennas) has a collecting area ten times that of the AMI-SA and longer baselines, crucially allowing the removal of the effects of confusing radio point sources from regions of low surface-brightness, extended emission. Moreover AMI provides fast, deep object surveying and allows monitoring of large numbers of objects. In this White Paper we review the new science - both Galactic and extragalactic - already achieved with AMI and outline the prospects for much more.https://arxiv.org/abs/1208.196
Signal and Data Transport for the SKA
No full textThe SKA will be a transformative radio telescope that will address fundamental unanswered questions about our Universe. The SKA will require high precision timing and will then generate unprecedented volumes of data. The Signal and Data Transport (SADT) Consortium has design the systems that address these requirements. I will discuss the design work undertaken by the SADT Consortium to address these challenges through three separate networks: • A network to transport the astronomical data (tens of Terabits per second), first from the receivers to a Central Signal Processor and then secondly transport the resultant data out of the telescope site to the Science Data Processor • A clock ensemble that provides a high accuracy timescale that can be tied to global UTC and a network that then distributes a reference frequency and absolute time to each antenna • A network that passes control, monitor and service data throughout the telescope
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