Search Publications

The physical properties of the Lyα forest at z > 1.5

Cristiani, S.; Giallongo, E.; Carswell, R. F. +2 more

Combining a new, increased data set of eight quasi-stellar objects (QSOs) covering the Lyα forest at redshifts 1.5 > z < 3.6 from VLT/UVES observations with previously published results, we have investigated the properties of the Lyα forest at 1.5 < z <4. With the six QSOs covering the Lyα forest at 1.5 < z < 2.5, we have extende…

Chandra observations of the luminous infrared galaxy NGC 3256

Zezas, A.; Ward, M.; Lira, P. +2 more

We present a detailed analysis of high-resolution Chandra observations of the merger system NGC 3256, the most infrared-luminous galaxy in the nearby universe. The X-ray data show that several discrete sources embedded in complex diffuse emission contribute >~20 per cent of the total emission (L^{tot_{X\sim 8\times 1041\,erg\,s…}}

Mass segregation in young compact star clusters in the Large Magellanic Cloud - II. Mass functions

Mackey, A. D.; de Grijs, R.; Gilmore, G. F. +1 more

We review the complications involved in the conversion of stellar luminosities into masses and apply a range of mass-to-luminosity relations to our Hubble Space Telescope observations of the young Large Magellanic Cloud (LMC) star clusters NGC 1805 and 1818.

Both the radial dependence of the mass function (MF) and the dependence of the cluste…

Chandra observations of RX J1347.5-1145: the distribution of mass in the most X-ray-luminous galaxy cluster known

Fabian, A. C.; Allen, S. W.; Schmidt, R. W.

We present Chandra observations of RX J1347.5-1145, the most X-ray-luminous cluster of galaxies known. We report the discovery of a region of relatively hot, bright X-ray emission, located approximately 20 arcsec to the south-east of the main X-ray peak at a position consistent with the region of enhanced Sunyaev-Zel'dovich effect reported recentl…

The initial conditions of isolated star formation - V. ISOPHOT imaging and the temperature and energy balance of pre-stellar cores

Ward-Thompson, D.; André, P.; Kirk, J. M.

ISO data taken with the long-wavelength imaging photo-polarimeter ISOPHOT are presented of 18 pre-stellar cores at three far-infrared wavelengths, 90, 170 and 200µm. Most of the cores are detected clearly at 170 and 200µm, but only one is detected strongly at 90µm, indicating that mostly they are very cold, with typical temperatu…

Dissecting the Homunculus nebula around Eta Carinae with spatially resolved near-infrared spectroscopy

Smith, Nathan

Near-infrared emission lines are unique diagnostics of the geometry, structure, kinematics, and excitation of the circumstellar ejecta of η Carinae, and give clues to the nature of its wind. The infrared spectrum is a strong function of position in η Car's nebula, with a mix of intrinsic and reflected emission. Molecular hydrogen traces cool gas a…

The evolving accretion disc in the black hole X-ray transient XTE J1859+226

Chaty, S.; Cui, W.; Shrader, C. R. +2 more

We present HST, RXTE, and UKIRT observations of the broad-band spectra of the black hole X-ray transient XTE J1859+226 during the decline from its 1999-2000 outburst. Our UV spectra define the 2175-Å interstellar absorption feature very well and based on its strength we estimate E(B-V)=0.58+/-0.12. Hence we deredden our spectra and follow the evol…

An observational study of a magneto-acoustic wave in the solar corona

Mathioudakis, M.; Keenan, F. P.; Phillips, K. J. H. +5 more

The Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-s oscillation in an active region coronal loop, during the 1999 August 11 total solar eclipse. In the present paper we show that this oscillation is associated with a fast-mode magneto-acoustic wave that travels through the loop apex with a velocity of 2100 km s^-1. We u…

Supernovae in deep Hubble Space Telescope galaxy cluster fields: cluster rates and field counts

Maoz, Dan; Sharon, Keren; Gal-Yam, Avishay

We have searched for high-redshift supernova (SN) candidates in multiple deep Hubble Space Telescope (HST ) archival images of nine galaxy cluster fields. We detect six apparent SNe, with 21.6<=I ₈₁₄ <=28.4mag. There is roughly 1 SN per deep (I ₈₁₄ >26mag), doubly-imaged WFPC2 cluster field. Two SNe are associated wi…

Maximum-entropy weak lens reconstruction: improved methods and application to data

Marshall, P. J.; Bridle, S. L.; Hobson, M. P. +1 more

We develop the maximum-entropy weak shear mass reconstruction method presented in earlier papers by taking each background galaxy image shape as an independent estimator of the reduced shear field and incorporating an intrinsic smoothness into the reconstruction. The characteristic length-scale of this smoothing is determined by Bayesian methods. …