D. J. Titterington - University Cambridge

D. J. Titterington
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Name
D. J. Titterington
Affiliation
University Cambridge
Country
United Kingdom

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Cosmology and Nongalactic Astrophysics (22)
 
Astrophysics of Galaxies (12)
 
High Energy Astrophysical Phenomena (10)
 
Astrophysics (9)
 
Solar and Stellar Astrophysics (5)
 
Instrumentation and Methods for Astrophysics (2)
 
Mathematics - Statistics (1)
 
Statistics - Theory (1)
 
Statistics - Methodology (1)
 
Statistics - Computation (1)

Publications Authored By D. J. Titterington

2016Nov
Affiliations: 1Oxford, 2Curtin, 3Oxford, 4Alberta, 5Cambridge, 6Cambridge, 7Cambridge, 8Manchester, 9Curtin, Amsterdam, 10Cambridge, 11Cambridge, 12Cambridge, 13Manchester, 14Cambridge, 15AAVSO

The connection between accretion and jet production in accreting white dwarf binary systems, especially dwarf novae, is not well understood. Radio wavelengths provide key insights into the mechanisms responsible for accelerating electrons, including jets and outflows. Here we present densely-sampled radio coverage, obtained with the Arcminute MicroKelvin Imager Large Array, of the dwarf nova SS Cyg during its February 2016 anomalous outburst. Read More

After more than 26 years in quiescence, the black hole transient V404 Cyg went into a luminous outburst in June 2015, and additional activity was detected in late December of the same year. Here, we present an optical spectroscopic follow-up of the December mini-outburst, together with X-ray, optical and radio monitoring that spanned more than a month. Strong flares with gradually increasing intensity are detected in the three spectral ranges during the ~10 days following the Swift trigger. Read More

We report on radio and X-ray monitoring observations of the BHC Swift J1753.5-0127 taken over a ~10 year period. Presented are daily radio observations at 15 GHz with the AMI-LA and X-ray data from Swift XRT and BAT. Read More

The Arcminute Microkelvin Imager Galactic Plane Survey (AMIGPS) provides mJy-sensitivity, arcminute-resolution interferometric images of the northern Galactic plane at $\approx$ 16 GHz. The first data release covered $76^{\circ} \lessapprox \ell \lessapprox 170^{\circ}$ between latitudes of $|b| \lessapprox 5^{\circ}$; here we present a second data release, extending the coverage to $53^{\circ} \lessapprox \ell \lessapprox 193^{\circ}$ and including high-latitude extensions to cover the Taurus and California giant molecular cloud regions, and the recently discovered large supernova remnant G159.6+7. Read More

2015Jun
Affiliations: 1ICRAR/Curtin, 2ICRAR/Curtin, 3Oxford, 4R. J. College, 5Oxford, 6U Southampton, 7USRA, 8Oxford, 9INAF-OAB, 10Oxford, 11Radboud U, 12Wheaton, 13API/UvA, 14XMM-NSOC, 15Cavendish Lab, 16NRC, 17NYU-AD, 18ICRAR/Curtin, 19U Virginia, 20U Alberta, 21ICRAR/Curtin, 22U Alberta, 23Cavendish Lab, 24ISS

XTE J1908+094 is an X-ray transient black hole candidate in the Galactic plane that was observed in outburst in 2002 and 2013. Here we present multi-frequency radio and X-ray data, including radio polarimetry, spanning the entire period of the 2013 outburst. We find that the X-ray behaviour of XTE J1908+094 traces the standard black hole hardness-intensity path, evolving from a hard state, through a soft state, before returning to a hard state and quiescence. Read More

We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel'dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement with higher angular resolution, 3 arcmin compared to the Planck beams of 5-10 arcmin. The AMI observations thus provide validation of the cluster detections, improved positional estimates, and a consistency check on the fitted 'size' ($\theta_{s}$) and 'flux' ($Y_{\rm tot}$) parameters in the Generalised Navarro, Frenk and White (GNFW) model. Read More

2014Mar
Affiliations: 1U. Southampton, 2U. Amsterdam, 3U. Southampton, 4U. Southampton, 5U. Amsterdam, 6U. Southampton, 7U. Cambridge, 8U. Cambridge, 9U. Amsterdam, 10U. Cambridge

We present one of the best sampled early time light curves of a gamma-ray burst (GRB) at radio wavelengths. Using the Arcminute Mircrokelvin Imager (AMI) we observed GRB 130427A at the central frequency of 15.7 GHz between 0. Read More

We have obtained deep SZ observations towards 15 of the apparently hottest XMM Cluster Survey (XCS) clusters that can be observed with the Arcminute Microkelvin Imager (AMI). We use a Bayesian analysis to quantify the significance of our SZ detections. We detect the SZ effect at high significance towards three of the clusters and at lower significance for a further two clusters. Read More

We present CARMA observations of a massive galaxy cluster discovered in the AMI blind SZ survey. Without knowledge of the cluster redshift a Bayesian analysis of the AMI, CARMA and joint AMI & CARMA uv-data is used to quantify the detection significance and parameterise both the physical and observational properties of the cluster whilst accounting for the statistics of primary CMB anisotropies, receiver noise and radio sources. The joint analysis of the AMI & CARMA uv-data was performed with two parametric physical cluster models: the {\beta}-model; and the model described in Olamaie et al. Read More

A subset of ultraluminous X-ray sources (those with luminosities < 10^40 erg/s) are thought to be powered by the accretion of gas onto black holes with masses of ~5-20 M_solar, probably via an accretion disc. The X-ray and radio emission are coupled in such Galactic sources, with the radio emission originating in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium precludes determining the causal sequence of events that leads to the ejection of the jet. Read More

We present 15-GHz follow-up radio observations of eleven Swift gamma-ray burst (GRB) sources, obtained with the Arcminute Microkelvin Imager Large Array (AMI-LA). The initial follow-up observation for each source was made in a fully automated fashion; as a result four observations were initiated within five minutes of the GRB alert timestamp. These observations provide the first millijansky-level constraints on prolonged radio emission from GRBs within the first hour post-burst. Read More

We present 16-GHz Sunyaev-Zel'dovich observations using the Arcminute Microkelvin Imager (AMI) and subsequent Bayesian analysis of six galaxy clusters at redshift ($z \approx 1$) chosen from an X-ray and Infrared selected sample from Culverhouse et al. (2010). In the subsequent analysis we use two cluster models, an isothermal \beta-model and a Dark Matter GNFW (DM-GNFW) model in order to derive a formal detection probability and the cluster parameters. Read More

The AMI Galactic Plane Survey (AMIGPS) is a large area survey of the outer Galactic plane to provide arcminute resolution images at milli-Jansky sensitivity in the centimetre-wave band. Here we present the first data release of the survey, consisting of 868 deg^2 of the Galactic plane, covering the area 76 deg \lessapprox l \lessapprox 170 deg between latitudes of |b| \lessapprox 5 deg, at a central frequency of 15.75 GHz (1. Read More

We study the properties of variational Bayes approximations for exponential family models with missing values. It is shown that the iterative algorithm for obtaining the variational Bayesian estimator converges locally to the true value with probability 1 as the sample size becomes inde nitely large. Moreover, the variational posterior distribution is proved to be asymptotically normal. Read More

We present 16 GHz (1.9 cm) deep radio continuum observations made with the Arcminute Microkelvin Imager (AMI) of a sample of low-mass young stars driving jets. We combine these new data with archival information from an extensive literature search to examine spectral energy distributions (SEDs) for each source and calculate both the radio and sub-mm spectral indices in two different scenarios: (1) fixing the dust temperature (Td) according to evolutionary class; (2) allowing Td to vary. Read More

The Planck Early Release Compact Source Catalogue includes 26 sources with no obvious matches in other radio catalogues (of primarily extragalactic sources). Here we present observations made with the Arcminute Microkelvin Imager Small Array (AMI SA) at 15.75 GHz of the eight of the unmatched sources at declination > +10 degrees. Read More

We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Serpens molecular cloud by the Spitzer c2d programme at a wavelength of 1.8cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). These observations have a resolution of ~30arcsec and an average sensitivity of 19microJy/beam. Read More

We present follow-up observations of two galaxy clusters detected blindly via the Sunyaev-Zel'dovich (SZ) effect and released in the Planck Early Release Compact Source Catalogue. We use the Arcminute Microkelvin Imager, a dual-array 14-18 GHz radio interferometer. After radio source subtraction, we find a SZ decrement of integrated flux density -1. Read More

2011Jan
Affiliations: 1AMI Consortium, 2AMI Consortium, 3AMI Consortium, 4AMI Consortium, 5AMI Consortium, 6AMI Consortium, 7AMI Consortium, 8AMI Consortium, 9AMI Consortium, 10AMI Consortium, 11AMI Consortium, 12AMI Consortium, 13AMI Consortium, 14AMI Consortium, 15AMI Consortium, 16AMI Consortium, 17AMI Consortium, 18AMI Consortium, 19AMI Consortium, 20AMI Consortium, 21AMI Consortium, 22AMI Consortium

We present an analysis of observations made with the Arcminute Microkelvin Imager (AMI) and the Canada-France-Hawaii Telescope (CFHT) of six galaxy clusters in a redshift range of 0.16--0.41. Read More

We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Perseus molecular cloud by the Spitzer c2d programme at a wavelength of 1.8 cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). We detect 72% of Class 0 objects from this sample and 31% of Class I objects. Read More

We present 16-GHz observations using the Arcminute Microkelvin Imager (AMI) of 11 clusters with 7 x 10^{37}W < L_X < 11 x 10^{37}W (h_{50}=1.0) selected from the Local Cluster Substructure Survey (LoCuSS) and compare them to X-ray data. We use a fast, Bayesian cluster analysis to explore the high-dimensional parameter space of the cluster-plus-sources model and obtain robust cluster parameter estimates in the presence of radio point sources, receiver noise and primordial CMB anisotropy. Read More

We present observations from the Small Array of the Arcminute Microkelvin Imager (AMI) of eight high X-ray luminosity galaxy cluster systems selected from the Local Cluster Substructure Survey (LoCuSS) sample.We detect the Sunyaev-Zel'dovich (SZ) effect in seven of these clusters. With the assumptions that galaxy clusters are isothermal, have a density profile described by a spherical b -model and obey the theoretical M-T relation, we are able to derive cluster parameters at r200 from our SZ data. Read More

Most Sunyaev--Zel'dovich (SZ) and X-ray analyses of galaxy clusters try to constrain the cluster total mass and/or gas mass using parameterised models and assumptions of spherical symmetry and hydrostatic equilibrium. By numerically exploring the probability distributions of the cluster parameters given the simulated interferometric SZ data in the context of Bayesian methods, and assuming a beta-model for the electron number density we investigate the capability of this model and analysis to return the simulated cluster input quantities via three rameterisations. In parameterisation I we assume that the T is an input parameter. Read More

We present an interesting Sunyaev-Zel'dovich (SZ) detection in the first of the Arcminute Microkelvin Imager (AMI) 'blind', degree-square fields to have been observed down to our target sensitivity of 100{\mu}Jy/beam. In follow-up deep pointed observations the SZ effect is detected with a maximum peak decrement greater than 8 \times the thermal noise. No corresponding emission is visible in the ROSAT all-sky X-ray survey and no cluster is evident in the Palomar all-sky optical survey. Read More

We perform deep 1.8 cm radio continuum imaging towards thirteen protostellar regions selected from the Spitzer c2d small clouds and cores programme at high resolution (25") in order to detect and quantify the cm-wave emission from deeply embedded young protostars. Within these regions we detect fifteen compact radio sources which we identify as radio protostars including two probable new detections. Read More

We report new cm-wave measurements at five frequencies between 15 and 18GHz of the continuum emission from the reportedly anomalous "region 4" of the nearby galaxy NGC6946. We find that the emission in this frequency range is significantly in excess of that measured at 8.5GHz, but has a spectrum from 15-18GHz consistent with optically thin free-free emission from a compact HII region. Read More

We present 25 arcsecond resolution radio images of five Lynds Dark Nebulae (L675, L944, L1103, L1111 & L1246) at 16 GHz made with the Arcminute Microkelvin Imager (AMI) Large Array. These objects were previously observed with the AMI Small Array to have an excess of emission at microwave frequencies relative to lower frequency radio data. In L675 we find a flat spectrum compact radio counterpart to the 850 micron emission seen with SCUBA and suggest that it is cm-wave emission from a previously unknown deeply embedded young protostar. Read More

2009Aug
Affiliations: 1The AMI Consortium, 2The AMI Consortium, 3The AMI Consortium, 4The AMI Consortium, 5The AMI Consortium, 6The AMI Consortium, 7The AMI Consortium, 8The AMI Consortium, 9The AMI Consortium, 10The AMI Consortium, 11The AMI Consortium, 12The AMI Consortium, 13The AMI Consortium, 14The AMI Consortium, 15The AMI Consortium, 16The AMI Consortium

Observations at 14.2 to 17.9 GHz made with the AMI Small Array towards fourteen Lynds Dark Nebulae with a resolution of 2' are reported. Read More

Using the Arcminute Microkelvin Imager (AMI) at 16 GHz and the Very Small Array (VSA) at 33 GHz to make follow-up observations of sources in the New Extragalactic WMAP Point Source Catalogue, we have investigated the flux-density variability in a complete sample of 97 sources over timescales of a few months to approximately 1.5 years. We find that 53 per cent of the 93 sources, for which we have multiple observations, are variable, at the 99 per cent confidence level, above the flux density calibration uncertainties of approximately 4 per cent at 16 GHz; the fraction of sources having varied by more than 20 per cent is 15 per cent at 16 GHz and 20 per cent at 33 GHz. Read More

We present follow-up observations of 97 point sources from the Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data, contained within the New Extragalactic WMAP Point Source (NEWPS) catalogue between declinations of -4 and +60 degrees; the sources form a flux-density-limited sample complete to 1.1 Jy (approximately 5 sigma) at 33 GHz. Our observations were made at 16 GHz using the Arcminute Microkelvin Imager (AMI) and at 33 GHz with the Very Small Array (VSA). Read More

2008Jul
Affiliations: 1Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 2Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 3Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 4Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 5Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 6Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 7Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 8Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 9Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 10Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 11Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 12Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 13Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 14Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 15Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 16Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 17Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 18Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 19Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 20Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 21Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 22Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 23Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 24Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 25Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 26Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 27Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 28Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 29Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 30Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 31Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 32Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 33Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 34Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 35Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 36Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 37Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 38Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 39Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 40Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 41Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 42Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 43Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 44Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 45Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 46Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 47Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 48Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 49Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 50Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 51Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 52Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 53Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 54Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 55Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 56Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 57Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 58Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 59Astrophysics Group, Cavendish Laboratory, Cambridge, UK, 60Astrophysics Group, Cavendish Laboratory, Cambridge, UK
Category: Astrophysics

The Arcminute Microkelvin Imager is a pair of interferometer arrays operating with six frequency channels spanning 13.9-18.2 GHz, with very high sensitivity to angular scales 30''-10'. Read More

We describe the objectives, design and predicted performance of Clover, which is a ground-based experiment to measure the faint ``B-mode'' polarisation pattern in the cosmic microwave background (CMB). To achieve this goal, clover will make polarimetric observations of approximately 1000 deg^2 of the sky in spectral bands centred on 97, 150 and 225 GHz. The observations will be made with a two-mirror compact range antenna fed by profiled corrugated horns. Read More

Accurate calibration of data is essential for the current generation of CMB experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 percent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. Read More

We present interferometric imaging at 33 GHz, with the new superextended configuration of the Very Small Array (VSA), of a very deep decrement in the cosmic microwave background (CMB) temperature. This decrement is located in the direction of the Corona Borealis supercluster, at a position with no known galaxy clusters, and was discovered by a previous VSA survey (Genova-Santos et al.). Read More

We present results from observations made at 33 GHz with the Very Small Array (VSA) telescope towards potential candidates in the Galactic plane for spinning dust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we find no evidence for anomalous emission and, in combination with Effelsberg data at 1.4 and 2. Read More

(Abridged) We have used the Rayner & Best (1989) smooth tests of goodness-of-fit to study the Gaussianity of the Very Small Array (VSA) data. Out of the 41 published VSA individual pointings dedicated to cosmological observations, 37 are found to be consistent with Gaussianity, whereas four pointings show deviations from Gaussianity. In two of them, these deviations can be explained as residual systematic effects of a few visibility points which, when corrected, have a negligible impact on the angular power spectrum. Read More