Search Publications
Evidence for X-ray obscuration in Type II quasar candidates from the Sloan Digital Sky Survey
Comastri, Andrea; Vignali, Cristian; Alexander, Dave M.
Recently, Zakamska et al. selected 291 high-ionization narrow-emission-line active galactic nuclei (AGN) in the redshift range 0.3-0.83 from the Sloan Digital Sky Survey (SDSS) spectroscopic data. The sample includes both type 2 Seyfert galaxies and their higher-luminosity `cousins', Type II quasar candidates. Here we present the results on the X-…
The nearest extreme starburst: bubbles, young star clusters and outflow in the merger NGC 3256
Taniguchi, Y.; Terlevich, R.; Díaz, R. J. +6 more
We have studied the extreme starburst in the infrared merger NGC 3256. We detect four galactic bubbles (using ESO New Technology Telescope and Hubble Space Telescope WFPC2 Hα images). These shells would be associated with previous supernova explosions.
The first analysis of the spatial distribution of young star cluster candidates shows that …The complex structure of low-luminosity active galactic nuclei: NGC 4579
Contini, Marcella
We have modelled the low-luminosity active galactic nucleus (AGN) NGC 4579 by explaining both the continuum and the line spectra observed with different apertures. It was found that the nuclear emission is dominated by an AGN such that the flux from the active centre (AC) is relatively low compared with that of the narrow emission-line region (NLR…
An X-ray absorption analysis of the high-velocity system in NGC 1275
Fabian, A. C.; Sanders, J. S.; Gillmon, K.
We present an X-ray absorption analysis of the high-velocity system (HVS) in NGC 1275 using results from a deep 200-ks Chandra observation. We are able to describe the morphology of the HVS in more detail than ever before. We present a Hubble Space Telescope image for comparison, and note close correspondence between the deepest X-ray absorption a…
Classical and MgII-selected damped Lyman α absorbers: impact on ΩHI at z < 1.7
Deharveng, Jean-Michel; Péroux, Céline; Cristiani, Stefano +1 more
The damped Lyα systems (DLAs), seen in absorption in the spectrum of background quasars, are believed to contain a large fraction of the neutral gas in the Universe. Paradoxically, these systems are more difficult to observe at zabs < 1.7, since they are rare and their HI feature then falls in UV spectra, thus requiring the use of sp…
Infrared mergers and infrared quasi-stellar objects with galactic winds - I. NGC 2623: nuclear outflow in a proto-elliptical candidate
Terlevich, R.; Lípari, S.; Díaz, R. J. +4 more
We present the first results of a study of the morphology, kinematics and ionization structure of infrared (IR) mergers/quasi-stellar objects (QSOs) with galactic winds. This study is based mainly on INTEGRAL two-dimensional (2D) fibre spectroscopy [obtained on the 4.2-m William Herschel Telescope (WHT), La Palma] combined with high-resolution Hub…
XMM-Newton observations of the merger-remnant galaxies NGC 3921 and 7252
Read, A. M.; Schweizer, François; Ponman, T. J. +1 more
Using the high sensitivity of XMM-Newton, we have studied the X-ray emission of the two prototypical late-stage merger remnants, NGC 3921 and 7252. In the case of NGC 7252, this is complemented by archival Chandra data. We investigate the nature of the discrete X-ray point source populations and the hot diffuse gas components in these two galaxies…
J320 (PN G190.3-17.7) as a poly-polar planetary nebula surrounded by point-symmetric knots
López, J. A.; Meaburn, J.; Holloway, A. J. +2 more
Spatially resolved, long-slit spectra obtained with the Manchester echelle spectrometer of the planetary nebula J320 have been compared with Hubble Space Telescope and ground-based images. The morphology and kinematics of the nebular core have been convincingly modelled using the XSHAPE code.
Two and possibly three bipolar lobes, expanding at…XMM-Newton observations of two X-ray-bright galaxy groups - pushing out to r500
Ponman, T. J.; Rasmussen, J.
We report on the results of XMM-Newton observations of the z= 0.18 galaxy group WARPJ0943.7+1644 and the nearby poor cluster WARPJ0943.5+1640 at z= 0.256. Tracing the X-ray gas out to ~425 and ~500 h-1 kpc in the two systems, corresponding to roughly 70 per cent of the estimated virial radii, we find the surface-brightness profile of bo…
The Needles in the Haystack Survey: searching for X-ray-selected normal galaxies
Georgantopoulos, I.; Plionis, M.; Georgakakis, A. E. +2 more
In this paper we present the first results from an ongoing serendipitous survey aiming to identify X-ray-selected `normal' galaxies [i.e. not dominated by active galactic nuclei (AGNs)] by combining archival XMM-Newton data with the Sloan Digital Sky Survey. In the first 4.5 deg2 of this program, we have identified a total of 11 `normal…