Search Publications
The star formation rate at redshift one: Hα spectroscopy with CIRPASS
Bunker, Andrew; Sharp, Robert; Dalton, Gavin +3 more
We have conducted an Hα survey of 38 0.77 <= z <= 1 galaxies over ~100arcmin2 of the Hubble Deep Field-North and Flanking Fields, to determine star formation rates (SFRs), with the near-IR multi-object spectrograph Cambridge Infrared Panoramic Survey Spectrograph (CIRPASS) on the William Herschel Telescope (WHT). This represents t…
X-ray observations of three young, early-type galaxies
Forbes, Duncan A.; Sansom, A. E.; O'Sullivan, E. +2 more
Massive haloes of hot plasma exist around some, but not all elliptical galaxies. There is evidence that this is related to the age of the galaxy. In this paper, new X-ray observations are presented for three early-type galaxies that show evidence of youth, in order to investigate their X-ray components and properties. NGC 5363 and NGC 2865 were fo…
Constraints on Galactic intermediate mass black holes
Rea, N.; Ferrara, A.; Mapelli, M.
Intermediate mass black holes (IMBHs; 101.3 to 105Msolar) are thought to form as relics of Population III stars or from the runaway collapse of stars in young clusters; their number and very existence are uncertain. We ran N-body simulations of Galactic IMBHs, modelling them as a halo population distributed accordi…
X-ray spectral properties of high-redshift radio-loud quasars beyond redshift 4 - first results*
Fabian, A. C.; Worsley, M. A.; Yuan, W. +1 more
We present the results of X-ray spectroscopic observations with XMM-Newton for four high-redshift radio-loud quasars at z > 4. Among these, three objects, namely GBB1508+5714, PMNJ0324-2918 and PKSB1251-407, do not show soft X-ray spectral flattening; the derived upper limits on assumed intrinsic absorption are (3.3-17.3) × 1021cm
Metallicity and absolute magnitude calibrations for UBV photometry
Karataş, Y.; Schuster, W. J.
Calibrations are presented here for metallicity ([Fe/H]) in terms of the ultraviolet excess, [δ(U - B) at B - V = 0.6, hereafter δ0.6], and also for the absolute visual magnitude (MV) and its difference with respect to the Hyades (ΔMHV) in terms of δ0.6 and (B - V), making use of high-resoluti…
XMM-Newton observations of Abell 2255: a test case of a merger after `core crossing'
Sakelliou, Irini; Ponman, Trevor J.
It has been known that Abell 2255 is not a relaxed cluster, but it is undergoing a merger. Here, we report on the analysis of the XMM-Newton observations of this cluster. The X-ray data give us the opportunity to reveal the complexity of the cluster, especially its temperature distribution. The integrated spectrum is well fitted by a single-temper…
Nuclear embedded star clusters in NGC 7582*
Galliano, E.; Wold, M.
We report on the discovery of several compact regions of mid-infrared emission in the star-forming circumnuclear disc of the starburst/Seyfert 2 galaxy NGC 7582. The compact sources do not have counterparts in the optical and near-infrared, suggesting that they are deeply embedded in dust. We use the [NeII] 12.8-µm line emission to estimate …
Orbital elements, masses and distance of λ Scorpii A and B determined with the Sydney University Stellar Interferometer and high-resolution spectroscopy
Uytterhoeven, K.; Aerts, C.; Tuthill, P. G. +7 more
The triple system HD158926 (λSco) has been observed interferometrically with the Sydney University Stellar Interferometer, and the elements of the wide orbit have been determined. These are significantly more accurate than the previous elements found spectroscopically. The inclination of the wide orbit is consistent with the inclination previously…
Optical spectroscopy of X-Mega targets in the Carina nebula - VI. FO15: a new O-type double-lined eclipsing binary
Barbá, R.; Morrell, N. I.; Niemela, V. S. +3 more
We report the discovery of a new O-type double-lined spectroscopic binary with a short orbital period of 1.4 d. We find the primary component of this binary, FO15, to have an approximate spectral type O5.5Vz, i.e. a zero-age main-sequence (ZAMS) star. The secondary appears to be of spectral type O9.5V. We have performed a numerical model fit to th…
The white dwarf in AE Aqr brakes harder
Mauche, Christopher W.
Taking advantage of the very precise de Jager et al. optical white dwarf orbit and spin ephemerides; ASCA, XMM-Newton and Chandra X-ray observations spread over 10yr and a cumulative 27-yr baseline, we have found that in recent years the white dwarf in AE Aqr is spinning down at a rate that is slightly faster than predicted by the de Jager et al. …