1,475 research outputs found
Investigating the source of Planck-detected AME: high resolution observations at 15 GHz
The Planck 28.5 GHz maps were searched for potential Anomalous Microwave
Emission (AME) regions on the scale of 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 {\sc Hii} region S140, we find evidence for
the characteristic rising spectrum associated with the either the spinning dust
mechanism for AME or an ultra/hyper-compact \textsc{Hii} region across the AMI
frequency band, however for AME-G173.6+2.8 we find no evidence for AME on
scales of arcmin.Comment: 13 pages, 8 figures, 4 tables. Submitted to Advances in Astronomy AME
Special Issu
TIME's past in the present: nostalgia and the black and white image
In 1995, the Hubble Space Telescope sent back to astronomers at the University of Arizona a series of vivid colour images of the Eagle Nebula, a dense formation of interstellar gas and dust the likes of which cradle newborn stars. As evidence that our perceptual universe, in every sense of the word, is defined by the representational powers of colour technology, the Hubble's “cosmic close-ups” are a clear case in point. Colour has become a standard representational form and hence the visual form. If so, what can be said of the recent popularity and proliferation of the black-and-white image?
No self-respecting café-bar or discriminating home, it seems, can now do without a black and white print on the wall. Commercial photography and certain forms of advertising have found a new niche in black and white, and even sepia is staging a come-back. The popularity of the black-and-white image cannot be divorced from the commercial culture in which it circulates; it is a “look” and a marker of taste. Monochrome is a stylistic trend but a revealing one, especially if one considers the growing preoccupation in America with heritage and memory. Both Susan Sontag and Roland Barthes give black and white a status of authenticity judged in relation to past time “properly” captured. For Sontag, monochrome gives an image a sense of age, historical distance, and aura. She writes, “the cold intimacy of color seems to seal off the photograph from patina.” Likewise, Barthes comments on the artifice of colour, how it is a “coating applied later on to the original truth of black and white.” For both critics, monochrome is an aesthetic of the authentic figured around a basic quality of pastness
Ancillary academia: video shorts and the production of university paratexts
This article considers the production of media paratexts beyond the bounds of the entertainment industry. Specifically, it examines the development of video content strategy by universities, and the paratextual function that video shorts serve in the construction of institutional identity. Taking a production studies approach, the article expands the scope of paratextual analysis by exploring the development of video content by university marketers, and the role of promotional intermediaries in selling video expertise to the education market
TIME's past in the present: nostalgia and the black and white image
In 1995, the Hubble Space Telescope sent back to astronomers at the University of Arizona a series of vivid colour images of the Eagle Nebula, a dense formation of interstellar gas and dust the likes of which cradle newborn stars. As evidence that our perceptual universe, in every sense of the word, is defined by the representational powers of colour technology, the Hubble's “cosmic close-ups” are a clear case in point. Colour has become a standard representational form and hence the visual form. If so, what can be said of the recent popularity and proliferation of the black-and-white image?
No self-respecting café-bar or discriminating home, it seems, can now do without a black and white print on the wall. Commercial photography and certain forms of advertising have found a new niche in black and white, and even sepia is staging a come-back. The popularity of the black-and-white image cannot be divorced from the commercial culture in which it circulates; it is a “look” and a marker of taste. Monochrome is a stylistic trend but a revealing one, especially if one considers the growing preoccupation in America with heritage and memory. Both Susan Sontag and Roland Barthes give black and white a status of authenticity judged in relation to past time “properly” captured. For Sontag, monochrome gives an image a sense of age, historical distance, and aura. She writes, “the cold intimacy of color seems to seal off the photograph from patina.” Likewise, Barthes comments on the artifice of colour, how it is a “coating applied later on to the original truth of black and white.” For both critics, monochrome is an aesthetic of the authentic figured around a basic quality of pastness
Aperture Array Configurations for SKA1 Core
This 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 forming station beams where elements
are shared between stations and apodisation is implemented, with the aim of
improving filling factor, overall sensitivity and sidelobe performance; the
disadvantages of such a scheme with regards to beam former requirements and
shortest available baseline are also discussed. At the station level, a
randomised configuration within a filled central region together with spiral
arms is explored
Characterization of Optical Frequency Transfer Over 154 km of Aerial Fiber
We present measurements of the frequency transfer stability and analysis of
the noise characteristics of an optical signal propagating over aerial
suspended fiber links up to 153.6 km in length. The measured frequency transfer
stability over these links is on the order of 10^-11 at an integration time of
one second dropping to 10^-12 for integration times longer than 100 s. We show
that wind-loading of the cable spans is the dominant source of short-timescale
noise on the fiber links. We also report an attempt to stabilize the optical
frequency transfer over these aerial links.Comment: 4 pages, submitted to Optics Letter
Bayesian modelling of clusters of galaxies from multi-frequency pointed Sunyaev--Zel'dovich observations
We present a Bayesian approach to modelling galaxy clusters using
multi-frequency pointed observations from telescopes that exploit the
Sunyaev--Zel'dovich effect. We use the recently developed MultiNest technique
(Feroz, Hobson & Bridges, 2008) to explore the high-dimensional parameter
spaces and also to calculate the Bayesian evidence. This permits robust
parameter estimation as well as model comparison. Tests on simulated Arcminute
Microkelvin Imager observations of a cluster, in the presence of primary CMB
signal, radio point sources (detected as well as an unresolved background) and
receiver noise, show that our algorithm is able to analyse jointly the data
from six frequency channels, sample the posterior space of the model and
calculate the Bayesian evidence very efficiently on a single processor. We also
illustrate the robustness of our detection process by applying it to a field
with radio sources and primordial CMB but no cluster, and show that indeed no
cluster is identified. The extension of our methodology to the detection and
modelling of multiple clusters in multi-frequency SZ survey data will be
described in a future work.Comment: 12 pages, 7 figures, submitted to MNRA
Detection of a CMB decrement towards a cluster of mJy radiosources
We present the results of radio, optical and near-infrared observations of
the field of TOC J0233.3+3021, a cluster of milliJansky radiosources from the
TexOx Cluster survey. In an observation of this field with the Ryle Telescope
(RT) at 15 GHz, we measure a decrement in the cosmic microwave background (CMB)
of Jy on the RT's 0.65 k baseline. Using
optical and infrared imaging with the McDonald 2.7-m Smith Reflector, Calar
Alto 3.5-m telescope and UKIRT, we identify the host galaxies of five of the
radiosources and measure magnitudes of , , .
The CMB decrement is consistent with the Sunyaev-Zel'dovich (SZ) effect of a
massive cluster of galaxies, which if modelled as a spherical King profile of
core radius has a central temperature decrement
of K. The magnitudes and colours of the galaxies are consistent with
those of old ellipticals at . We therefore conclude that TOC
J0233.3+3021 is a massive, high redshift cluster. These observations add to the
growing evidence for a significant population of massive clusters at high
redshift, and demonstrate the effectiveness of combining searches for AGN
`signposts' to clusters with the redshift-independence of the SZ effect.Comment: Six pages; accepted for publication in MNRAS. Version with
full-resolution UV plot available from
http://www.mrao.cam.ac.uk/~garret/MB185.p
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