Search Publications
Failed disc winds: a physical origin for the soft X-ray excess?
Schurch, N. J.; Done, C.
The origin of the soft X-ray excess emission observed in many type-1 active galactic nuclei (AGN) has been an unresolved problem in X-ray astronomy for over two decades. We develop the model proposed by Gierliński & Done, which models the soft excess with heavily smeared, ionized, absorption, by including the emission that must be associated w…
An XMM-Newton observation of the massive edge-on Sb galaxy NGC 2613
Wang, Q. D.; Li, Z.; Irwin, J. A. +1 more
We present an XMM-Newton observation of the massive edge-on Sb galaxy NGC 2613. We discover that this galaxy contains a deeply embedded active nucleus with a 0.3-10 keV luminosity of 3.3 × 1040ergs-1 and a line-of-sight absorption column of 1.2 × 1023cm-2. Within the 25 magarcsec-2 optical B-b…
NGC 4435: a bulge-dominated galaxy with an unforeseen low-mass central black hole
Dalla Bontà, E.; Corsini, E. M.; Pizzella, A. +3 more
We present the ionized gas kinematics of the SB0 galaxy NGC 4435 from spectra obtained with the Space Telescope Imaging Spectrograph. This galaxy has been selected on the basis of its ground-based spectroscopy, for displaying a position-velocity diagram consistent with the presence of a circumnuclear Keplerian disc rotating around a supermassive b…
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 …