Search Publications
Hubble Space Telescope Wide Field Planetary Camera 2 observations of hyperluminous infrared galaxies
Farrah, D.; Verma, A.; Rowan-Robinson, M. +2 more
We present Hubble Space Telescope Wide Field Planetary Camera 2 I-band imaging for a sample of nine hyperluminous infrared galaxies (HLIRGs) spanning a redshift range 0.45<z<1.34. Three of the sample have morphologies showing evidence for interactions and six are quasi-stellar objects (QSOs). Host galaxies in the QSOs are detected reliably o…
Clues about the star formation history of the M31 disc from WFPC2 photometry
Williams, Benjamin F.
Over the past several years, the Hubble Space Telescope (HST) has acquired many broad-band images of various regions in the M31 disc. I have obtained 27 such fields from the HST data archive in order to produce colour-magnitude diagrams (CMDs) of the stellar populations contained within these areas of the disc. I have attempted to reproduce these …
2016+112: a gravitationally lensed type II quasar
Lawrence, C. R.; Blandford, R. D.; Koopmans, L. V. E. +3 more
<
A single-screen model of the gravitational lens system 2016+112 is proposed, that explains recent Hubble Space Telescope (HST) infrared (NICMOS-F160W) observations and new high-resolution European VLBI Network (EVN) 5-GHz radio observations, presented in this paper. In particular, we find that a massive `dark' structure at the lens posit…Discovery of the `missing' mode in HR1217 by the Whole Earth Telescope
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +35 more
HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6µHz, with a sixth mode at a problematic spacing of 50.0µHz (which equals to the high-frequency side. As…
Crystalline silicates in the envelopes and discs around oxygen-rich asymptotic giant branch stars
Suh, Kyung-Won
We have modelled dust envelopes and discs around oxygen-rich asymptotic giant branch (AGB) stars using optical properties of amorphous and crystalline silicate dust grains, paying close attention to the infrared observations of the stars including the Infrared Space Observatory (ISO ) data. Using the opacity functions for various mixtures of amorp…
Observations of the Hubble Deep Field South with the Infrared Space Observatory - I. Observations, data reduction and mid-infrared source counts
Oliver, Seb; Elbaz, David; Franceschini, Alberto +14 more
We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15µm with the ISOCAM instrument on board the Infrared Space Observatory (ISO ). The final map in each band was constructed by the co-addition of four independent rasters, registered using bright sources securely detected in a…
On the detectability of distant Compton-thick obscured quasars
Fabian, A. C.; Crawford, C. S.; Wilman, R. J.
Chandra and XMM-Newton have resolved the 2-8keV X-ray background (XRB) into point sources. Many of the fainter sources are obscured active galactic nuclei (AGN) with column densities in the range of 1022-1023cm-2, some of which have quasar-like luminosities. According to obscuration models, the XRB above 8keV is do…
Multiple X-ray reflection from ionized slabs
Fabian, A. C.; Ross, R. R.; Ballantyne, D. R.
Multiple reflection of X-rays may be important when an accretion disc and its hot corona have a complicated geometry, or if returning radiation due to gravitational light bending is important, or in emission from a funnel such as proposed in some γ-ray burst models. We simulate the effects of multiple reflection by modifying the boundary condition…
The 69-µm forsterite band as a dust temperature indicator
Waters, L. B. F. M.; Ade, P. A. R.; Barlow, M. J. +6 more
A band of pure crystalline forsterite (100 per cent Mg2SiO4) occurs at 69.67µm at room temperature (295K) for olivines with >~10 per cent Fe the corresponding feature is at >~73µm. The Mg-rich forsterite feature is observed in a variety of ISO LWS spectra, but the corresponding Fe-rich olivine feature is not…
Chandra HRC and HST observations of NGC 6240: resolving the active galactic nucleus and starburst
Zezas, A.; Murray, S. S.; Lira, P. +1 more
We present high spatial resolution X-ray Chandra HRC and HST WFPC2 Hα observations of the prototypical infrared-luminous galaxy NGC 6240. The central region of this system shows a remarkably complex morphology, with filaments and loops observed in the optical and X-rays. The total X-ray luminosity is dominated by the extended emission. Both nuclei…