11,933 research outputs found
6C radio galaxies at z~1: The influence of radio power on the alignment effect
Powerful radio galaxies often display enhanced optical/UV continuum emission
and extended emission line regions, elongated and aligned with the radio jet
axis. The expansion of the radio source strongly affects the gas clouds in the
surrounding IGM, and the kinematic and ionization properties of the extended
emission line regions display considerable variation over the lifetime of
individual sources, as well as with cosmic epoch. We present the results of
deep rest-frame UV and optical imaging and UV spectroscopy of high redshift 6C
radio galaxies. The interdependence of the host galaxy and radio source
properties are discussed, considering: (i) the relative contribution of shocks
associated with the expanding radio source to the observed emission line gas
kinematics, and their effect on the ionization state of the gas; (ii) the
similarities and differences between the morphologies of the host galaxies and
aligned emission for a range of radio source powers; and (iii) the influence of
radio power on the strength of the observed alignment effect.Comment: LaTeX, 6 pages, 5 figures, Elsevier Science format. To appear in
"Radio galaxies: past, present & future". eds. M. Jarvis et al., Leiden, Nov
200
The final two redshifts for radio sources from the equatorial BRL sample
Best, Rottgering and Lehnert (1999, 2000a) defined a new sample of powerful
radio sources from the Molonglo Reference Catalogue, for which redshifts were
compiled or measured for 177 of the 178 objects. For the final object,
MRC1059-010 (3C249), the host galaxy is here identified using near-infrared
imaging, and the redshift is determined from VLT spectroscopy. For one other
object in the sample, MRC0320+053 (4C05.14), the literature redshift has been
questioned: new spectroscopic observations of this object are presented,
deriving a corrected redshift. With these two results, the spectroscopic
completeness of this sample is now 100%.
New redshifts are also presented for PKS0742+10 from the Wall & Peacock 2.7
GHz catalogue, and PKS1336+003 from the Parkes Selected Regions. PKS0742+10
shows a strong neutral hydrogen absorption feature in its Lyman-alpha emission
profile.Comment: 4 pages. LaTeX. Accepted for publication in MNRA
A jet-cloud interaction in 3C34 at redshift z = 0.69
We report the detection of a strong jet-cloud interaction at a distance of
120 kpc from the nucleus of the radio galaxy 3C34, which has redshift z=0.69.
Hubble Space Telescope images of the radio galaxy show a long narrow region of
blue emission orientated along the radio axis and directed towards a radio
hotspot. The William Herschel Telescope has been used to provide long-slit
spectroscopic data of this object, and infrared observations made with the
United Kingdom InfraRed Telescope have enabled its spectral energy distribution
to be modelled. We propose that the aligned emission is associated with a
region of massive star-formation, induced by the passage of the radio jet
through a galaxy within the cluster surrounding 3C34. A star-formation rate of
about 100 solar masses per year is required, similar to the values necessary to
produce the alignment effect in high-redshift radio galaxies. The consequences
of this result for models of star formation in distant radio galaxies are
discussed.Comment: 12 pages including 11 figures, LaTeX. To appear in MNRA
Conversation therapy for agrammatism: exploring the therapeutic process of engagement and learning by a person with aphasia.
A recent systematic review of conversation training for communication partners of people with aphasia has shown that it is effective, and improves participation in conversation for people with chronic aphasia. Other research suggests that people with aphasia are better able to learn communication strategies in an environment which closely mirrors that of expected use, and that cognitive flexibility may be a better predictor of response to therapy than severity of language impairment. This study reports results for a single case, one of a case series evaluation of a programme of conversation training for agrammatism that directly involves a person with aphasia (PWA) as well as their communication partner. It explores how a PWA is able to engage with and learn from the therapy, and whether this leads to qualitative change in post-therapy conversation behaviours
An investigation into the impact of coaching strategies with respect to physical and performance characteristics of male youth of varying biological maturation
This thesis will be presented as two standalone experimental chapters which will culminate in a thesis discussion linking the two papers under the overarching concept of maturation in male youth. Chapter 2 is currently under review in âCogent Medicineâ, and the intention of Chapter 2 is to identify physical, injury and performance-based differences between maturational groups within a general school-based population of 8 youth. These observed differences within Chapter 2 will then inform the methodology and coaching strategies utilised within Chapter 3, which will investigate the effectiveness of various coaching methods in order to maximise adaptation, motor ability and injury prevention within each maturational group. The outcome of this thesis hopes to inform practitioners as to how they can best implement their training programmes to maximise learning and adaptation across a range of biological maturation levels. Rather than just knowing when training should occur which has been investigated previously, it is hoped this thesis will provide insight into how coaching should occur to maximise learning within this diverse adolescent population. Due to the layout of this thesis with the individual papers, there is an element of content repetition throughout Chapters 1,2,3 and 4 which needs to be acknowledged, although the various contexts provides uniqueness throughout
HST and UKIRT imaging observations of z ~ 1 6C radio galaxies - I. The data
The results of Hubble Space Telescope and UKIRT imaging observations are
presented for a sample of 11 6C radio galaxies with redshifts 0.85 < z < 1.5.
The observations of the 6C sources reveal a variety of different features,
similar to those observed around the higher luminosity of the aligned emission
appears less extreme in the case of the 6C radio galaxies. For both samples,
the aligned emission clearly cannot be explained by a single emission
mechanism; line emission and related nebular continuum emission, however, often
provide a significant contribution to the aligned emission.Comment: 17 pages, 11 figures (figs 3,6,11 low resolution - full resolution
images can be obtained from http://www.mrao.cam.ac.uk/~kji/ImagingFigs/).
Accepted for publication in MNRA
HST, radio and infrared observations of 28 3CR radio galaxies at redshift z ~ 1: I. The observations
Hubble Space Telescope images are presented of a sample of 28 3CR radio
galaxies with redshifts in the range 0.6 < z < 1.8, together with maps at
comparable angular resolution of their radio structure, taken using the Very
Large Array. Infrared images of the fields, taken with the United Kingdom
InfraRed Telescope, are also presented. The optical images display a
spectacular range of structures. Many of the galaxies show highly elongated
optical emission aligned along the directions of the radio axes, but this is
not a universal effect; a small number of sources are either symmetrical or
misaligned. Amongst those sources which do show an alignment effect, the
morphology of the optical emission varies greatly, from a single bright
elongated emission region to strings of optical knots stretching from one radio
hotspot to the other. The infrared images display much less complexity.
Although their significantly lower angular resolution would wash out some of
the smaller structures seen in the HST images, it is clear that these galaxies
are less aligned at infrared wavelengths than in the optical. In this paper, we
discuss the galaxies individually, but defer a statistical analysis of the
multi-waveband properties of the complete sample of sources to later papers in
this series.Comment: 39 pages including 52 figures, LaTeX. Accepted for publication in
MNRA
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