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A. W. Jones

Publications and source records attributed to A. W. Jones.

13 recordsLinked to original sources
arXiv2021

An Interactive Gravitational-Wave Detector Model for Museums and Fairs

In 2015 the first observation of gravitational waves marked a breakthrough in astrophysics, and in technological research and development. The discovery of a gravitational-wave signal from the collision of two black holes, a billion light-years away, received considerable interest from the media and public. We describe the development of a purpose-built exhibit explaining this new area of research to a general audience. The core element of the exhibit is a working Michelson interferometer: a scaled-down version of the key technology used in gravitational-wave detectors. The Michelson interferometer is integrated into a hands-on exhibit, which allows for user interaction and simulated gravitational-wave observations. An interactive display provides a self-guided explanation of gravitational-wave-related topics through video, animation, images and text. We detail the hardware and software used to create the exhibit and discuss two installation variants: an independent learning experience in a museum setting (the Thinktank Birmingham Science Museum), and a science-festival with the presence of expert guides (the 2017 Royal Society Summer Science Exhibition). We assess audience reception in these two settings, describe the improvements we have made given this information, and discuss future public-engagement projects resulting from this work. The exhibit is found to be effective in communicating the new and unfamiliar field of gravitational-wave research to general audiences. An accompanying website provides parts lists and information for others to build their own version of this exhibit.

physics.ed-ph↗
arXiv2020

High Dynamic Range Spatial Mode Decomposition

Accurate readout of low-power optical higher-order spatial modes is of increasing importance to the precision metrology community. Mode sensors are used to prevent mode mismatches from degrading quantum and thermal noise mitigation strategies. Direct mode analysis sensors (MODAN) are a promising technology for real-time monitoring of arbitrary higher-order modes. We demonstrate MODAN with photo-diode readout to mitigate the typically low dynamic range of CCDs. We look for asymmetries in the response our sensor to break degeneracies in the relative alignment of the MODAN and photo-diode and consequently improve the dynamic range of the mode sensor. We provide a tolerance analysis and show methodology that can be applied for sensors beyond first-order spatial modes.

physics.ins-det↗
arXiv2000

On dust-correlated Galactic emission in the Tenerife data

Recently correlation analyses between Galactic dust emission templates and a number of CMB data sets have led to differing claims on the origin of the Galactic contamination at low frequencies. de Oliviera-Costa {\em et al} (1999) have presented work based on Tenerife data supporting the spinning dust hypothesis. Since the frequency coverage of these data is ideal to discriminate spectrally between spinning dust and free-free emission, we used the latest version of the Tenerife data, which have lower systematic uncertainty, to study the correlation in more detail. We found however that the evidence in favor of spinning dust originates from a small region at low Galactic latitude where the significance of the correlation itself is low and is compromised by systematic effects in the Galactic plane signal. The rest of the region was found to be uncorrelated. Regions that correlate with higher significance tend to have a steeper spectrum, as is expected for free-free emission. Averaging over all correlated regions yields dust-correlation coefficients of $180\pm47$ and $123\pm16$ $μ$K /MJy sr$^{-1}$ at 10 and 15 GHz respectively. These numbers however have large systematic uncertainties that we have identified and care should be taken when comparing with results from other experiments. We do find evidence for synchrotron emission with spectral index steepening from radio to microwave frequencies, but we cannot make conclusive claims about the origin of the dust-correlated component based on the spectral index estimates. Data with higher sensitivity are required to decide about the significance of the dust-correlation at high Galactic latitudes and other Galactic templates, in particular H$_α$ maps, will be necessary for constraining its origin.

astro-ph↗
arXiv1999

Foregrounds and experiments below 33GHz

In this paper I report on the recent results obtained from the Tenerife switched beam (10 GHz to 33 GHz) experiment and Jodrell Bank 5 GHz interferometer and their predictions for foreground levels. The full data analysis and results will be presented elsewhere. It is found that free-free emission dominates above 10 GHz, whereas synchrotron emission dominates below 5 GHz.

astro-ph↗
arXiv1999

Cosmic Microwave background map making with data between 10 and 90GHz

We use data from the Tenerife 10, 15 and 33 GHz beamswitching experiments along with the COBE 53 and 90 GHz data to separate the cosmic microwave background (CMB) signal from the Galactic signal and create two maps at high Galactic latitude. The new multi-MEM technique is used to obtain the best reconstruction of the two channels. The two maps are presented and known features are identified within each. We find that the Galactic contribution to both the 15 and 33 GHz Tenerife data is small enough to be ignored when compared to the errors in the data and the magnitude of the CMB signal.

astro-ph↗
arXiv1999

Application of novel analysis techniques to Cosmic Microwave Background astronomy

The data from Cosmic Microwave Background (CMB) experiments are becoming more complex with each new experiment. A consistent way of analysing these data sets is required so that direct comparison is possible between the various experimental results. This thesis presents several techniques that can be used to analyse CMB data.

astro-ph↗
arXiv1998

Separation of foregrounds from cosmic microwave background observations with the MAP satellite

Simulated observations of a $10\dg \times 10\dg$ field by the Microwave Anisotropy Probe (MAP) are analysed in order to separate cosmic microwave background (CMB) emission from foreground contaminants and instrumental noise and thereby determine how accurately the CMB emission can be recovered. The simulations include emission from the CMB, the kinetic and thermal Sunyaev-Zel'dovich (SZ) effects from galaxy clusters, as well as Galactic dust, free-free and synchrotron. We find that, even in the presence of these contaminating foregrounds, the CMB map is reconstructed with an rms accuracy of about 20 $μ$K per 12.6 arcmin pixel, which represents a substantial improvement as compared to the individual temperature sensitivities of the raw data channels. We also find, for the single $10\dg \times 10\dg$ field, that the CMB power spectrum is accurately recovered for $\ell \la 600$.

astro-ph↗
arXiv1998

The effect of point sources on satellite observations of the cosmic microwave background

We study the effect of extragalactic point sources on satellite observations of the cosmic microwave background (CMB). In order to separate the contributions due to different foreground components, a maximum-entropy method is applied to simulated observations by the Planck Surveyor satellite. In addition to point sources, the simulations include emission from the CMB and the kinetic and thermal Sunyaev-Zel'dovich (SZ) effects from galaxy clusters, as well as Galactic dust, free-free and synchrotron emission. We find that the main input components are faithfully recovered and, in particular, that the quality of the CMB reconstruction is only slightly reduced by the presence of point sources. In addition, we find that it is possible to recover accurate point source catalogues at each of the Planck Surveyor observing frequencies.

astro-ph↗
arXiv1998

Observations of the Cosmic Microwave Background and Implications for Cosmology and Large Scale Structure

Observations of the Cosmic Microwave Background (CMB) are discussed, with particular emphasis on current ground-based experiments and on future satellite, balloon and interferometer experiments. Observational techniques and the effects of contaminating foregrounds are highlighted. Recent CMB data is used with large scale structure (LSS) data to constrain cosmological parameters and the complementary nature of CMB, LSS and supernova distance data is emphasized.

astro-ph↗
arXiv1998

Review of Ground-Based CMB Experiments

We present in this paper a brief review of Ground-Based Cosmic Microwave Background (CMB) experiments. We first recall the main experimental problems and adopted solutions. We then review the Tenerife experiments, giving an update together with some new results. Then results and problems from other experiments are highlighted including IAC-Bartol, Python, Saskatoon, Mobile Anisotropy Telecope (MAT) and the Owen Valley Radio Observatory (OVRO) experiments. We next move on to the future ground experiments, in particular new interferometers such as the Very Small Array (VSA), the Cosmic Background Imager (CBI) and the Degree Angular Scale Interferometer (DASI/VCA). To finish, very recent work is presented on joint likelihood analysis for estimation of cosmological parameters where both CMB results and Large Scale Structure (LSS) surveys are considered.

astro-ph↗
arXiv1998

10 GHz Tenerife CMB observations at 8 degree resolution and their analysis using a new maximum entropy method

The complete set of data from the Tenerife 10 GHz (8 degree FWHM) twin-horn, drift scan experiment is described. These data are affected by both long-term atmospheric baseline drifts and short term noise. A new maximum entropy procedure, utilising the time invariance and spatial continuity of the astronomical signal, is used to achieve a clean separation of these effects from the astronomical signal, and to deconvolve the effects of the beam-switching. We use a fully positive/negative algorithm to produce two-dimensional maps of the intrinsic sky fluctuations. Known discrete sources and Galactic features are identified in the deconvolved map. The data from the 10 GHz experiment, after baseline subtraction with MEM, is then analysed using conventional techniques and new constraints on Galactic emission are made.

astro-ph↗
arXiv1997

New Cosmological Structures on Medium Angular Scales Detected with the Tenerife Experiments

We present observations at 10 and 15 GHz taken with the Tenerife experiments in a band of the sky at Dec.=+35 degrees. These experiments are sensitive to multipoles in the range l=10-30. The sensitivity per beam is 56 and 20 microK for the 10 and the 15 GHz data, respectively. After subtraction of the prediction of known radio-sources, the analysis of the data at 15 GHz at high Galactic latitude shows the presence of a signal with amplitude Delta Trms ~ 32 microK. In the case of a Harrison-Zeldovich spectrum for the primordial fluctuations, a likelihood analysis shows that this signal corresponds to a quadrupole amplitude Q_rms-ps=20.1+7.1-5.4 microK, in agreement with our previous results at Dec.+=40 degrees and with the results of the COBE DMR. There is clear evidence for the presence of individual features in the RA range 190 degrees to 250 degrees with a peak to peak amplitude of ~110 microK. A preliminary comparison between our results and COBE DMR predictions for the Tenerife experiments clearly indicates the presence of individual features common to both. The constancy in amplitude over such a large range in frequency (10-90 GHz) is strongly indicative of an intrinsic cosmological origin for these structures.

astro-ph↗