Search Publications
X-ray reflection in the Seyfert galaxy 1H 0419-577 revealing strong relativistic effects in the vicinity of a Kerr black hole
Iwasawa, K.; Fabian, A. C.; Miniutti, G. +1 more
We report results obtained from six XMM-Newton observations of the Seyfert galaxy 1H 0419-577. The source was observed in a wide range of different flux levels, allowing its long-term spectral variability to be studied in detail, as already reported recently by Pounds et al. Here we show that the X-ray spectrum is well described by a simple two-co…
Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B*
Bond, Howard E.; Barstow, M. A.; Koester, D. +3 more
Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from space we can take advantage of the superb spatial resolution of the Hubble Space Telescope (HST) to resolve the A and B components. Since the closest…
A jet-induced outflow of warm gas in 3C293
Morganti, R.; Tadhunter, C. N.; Holt, J. +3 more
Using long-slit emission-line spectra we detect a fast outflow of ionized gas, with velocities up to 1000 km s-1, in the nearby powerful radio galaxy 3C293 (z= 0.045). The fast outflow is located about 1 kpc east of the nucleus, in a region of enhanced radio emission due to the presence of a distorted radio jet. We present results that …
An old quasar in a young dark energy-dominated universe?
Friaça, A. C. S.; Alcaniz, J. S.; Lima, J. A. S.
Dark energy is the invisible fuel that seems to drive the current acceleration of the Universe. Its presence, which is inferred from an impressive convergence of high-quality observational results along with some apparently successful theoretical predictions, is also supported by the current estimates of the age of the Universe from dating of loca…
Fe K emission in the ultraluminous infrared galaxy Arp 220
Sanders, D. B.; Iwasawa, K.; Miniutti, G. +3 more
Prominent Fe Kα line emission is detected in the XMM-Newton spectrum of the ultraluminous infrared galaxy Arp 220. The centroid of the line is found at an energy of 6.7 keV and the equivalent width of the line is EW ~ 1.9 keV (at 3.5σ significance). A few other spectral features are found at various degrees of significance in the lower energy rang…
Submillimetre photometry of X-ray absorbed quasi-stellar objects: their formation and evolutionary status
Ivison, R. J.; Smail, Ian; Page, M. J. +4 more
We present an analysis of the submillimetre/X-ray properties of 19 X-ray absorbed, Compton-thin quasi-stellar objects (QSOs) selected to have luminosities and redshifts that represent the peak of cosmic QSO activity, i.e. ~L* objects at 1 < z < 3. Of these, we present new data for 11 objects not previously observed at submillimetre wavelengt…
The XMM Large-Scale Structure survey: an initial sample of galaxy groups and clusters to a redshift z < 0.6*
Altieri, B.; Valtchanov, I.; Pierre, M. +14 more
We present X-ray and optical spectroscopic observations of 12 galaxy groups and clusters identified within the X-ray Multi-Mirror (XMM) Large-Scale Structure (LSS) survey. Groups and clusters are selected as extended X-ray sources from a 3.5 deg2XMM image mosaic above a flux limit 8 × 10-15 erg s-1 cm-2 …
FeXXV and FeXXVI lines from low-velocity, photoionized gas in the X-ray spectra of active galactic nuclei
Nicastro, Fabrizio; Bianchi, Stefano; Matt, Giorgio +2 more
We have calculated the equivalent widths of the absorption lines produced by FeXXV and FeXXVI in a Compton-thin, low-velocity photoionized material illuminated by the nuclear continuum in active galactic nuclei. The results, plotted against the ionization parameter and the column density of the gas, are a complement to those presented by Bianchi &…
The extended Hα-emitting filaments surrounding NGC 4696, the central galaxy of the Centaurus cluster
Fabian, A. C.; Sanders, J. S.; Crawford, C. S. +1 more
We present images of NGC 4696, the central galaxy in the Centaurus cluster, showing the large extent of cool filaments that are bright in Hα line emission. These filaments share the detailed structure of both the central dust lane and the inner regions of the arc-like plumes seen in soft X-ray emission. The X-ray gas is at its coolest and most abs…
The Hubble constant from the gravitational lens CLASS B0218+357 using the Advanced Camera for Surveys
Jackson, N.; Browne, I. W. A.; York, T. +2 more
We present deep optical observations of the gravitational lens system CLASS B0218+357, from which we derive an estimate for the Hubble constant (H0). Extensive radio observations using the VLA, MERLIN, the VLBA and VLBI have reduced the degeneracies between H0 and the mass model parameters in this lens to one involving only t…