Search Publications
The quasar PG 0844+349 in an X-ray weak state
Schartel, N.; Fabian, A. C.; Komossa, S. +4 more
In 2009 March the well-studied quasar, PG 0844+349, was discovered with Swift to be in an X-ray weak state. A follow-up XMM-Newton observation several weeks later generated a good-quality spectrum of the source, showing substantial curvature and spectral hardening. In combination with archival data at two previous epochs when the source was in a b…
The Planck-ATCA Coeval Observations project: the faint sample
Bonaldi, Anna; de Zotti, Gianfranco; Massardi, Marcella +3 more
The Planck-ATCA Coeval Observations (PACO) project collected data between 4.5 and 40 GHz for 482 sources selected within the Australia Telescope 20 GHz (AT20G) catalogue and observed with the Australia Telescope Compact Array. Observations were done almost simultaneously with the Planck satellite, in the period between 2009 July and 2010 August. I…
Colour gradients in normal and compact early-type galaxies at 1 < z < 2
Longhetti, M.; Gargiulo, A.; Saracco, P.
We have derived colour gradients for a sample of 20 early-type galaxies (ETGs) at 1 < zspec < 2 selected from the GOODS-South field. The sample includes both normal ETGs (13) having effective radii comparable to the mean radius of local ones and compact ETGs (seven) having effective radii from two to six times smaller. Colour grad…
AzTEC 1.1-mm images of 16 radio galaxies at 0.5 < z < 5.2 and a quasar at z= 6.3
Yun, M. S.; Kohno, K.; Humphrey, A. +12 more
We present 1.1-mm observations for a sample of 16 powerful radio galaxies at 0.5 < z < 5.2 and a radio-quiet quasar at z = 6.3, obtained using the AzTEC bolometer array mounted on the Atacama Submillimetre Telescope Experiment (ASTE) or the James Clerk Maxwell Telescope (JCMT). This paper more than doubles the number of high-z radio galaxies…
Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations
Jorda, L.; Lamy, P. L.; A'Hearn, M. F. +2 more
We report on our on-going effort to detect and characterize cometary nuclei with the Hubble Space Telescope (HST). During cycle 9 (2000 July to 2001 June), we performed multi-orbit observations of 10 ecliptic comets with the Wide Field Planetary Camera 2. Nominally, eight contiguous orbits covering a time interval of ∼11 h were devoted to each com…
Observational constraints on the physics behind the evolution of active galactic nuclei since z∼ 1
Cooper, M. C.; Juneau, S.; Georgakakis, A. +7 more
We explore the evolution with redshift of the rest-frame colours and space densities of active galactic nuclei (AGN) hosts (relative to normal galaxies) to shed light on the dominant mechanism that triggers accretion on to supermassive black holes as a function of cosmic time. Data from serendipitous wide-area XMM surveys of the Sloan Digital Sky …
Discovery of a broad O VIII Lyα line in the ultracompact X-ray binary 4U 1543-624
Jonker, P. G.; Madej, O. K.
We report the discovery of a broad emission feature at ∼0.7 keV in the spectra of the ultracompact X-ray binary 4U 1543-624, obtained with the high-resolution spectrographs of the XMM-Newton and Chandra satellites. We confirm the presence of the feature in the broad-band MOS2 spectrum of the source. As suggested before in the literature, the donor…
A deep spectroscopic study of the filamentary nebulosity in NGC 4696, the brightest cluster galaxy in the Centaurus cluster
Fabian, A. C.; Ferland, G. J.; Sanders, J. S. +4 more
We present results of deep integral-field spectroscopy observations using high-resolution optical (4150-7200 Å) VLT VIsible MultiObject Spectrograph spectra of NGC 4696, the dominant galaxy in the Centaurus cluster (Abell 3526). After the Virgo cluster, this is the second nearest (z= 0.0104) example of a cool-core cluster. NGC 4696 is surrounded b…
A detailed spectral study of GRB 041219A and its host galaxy
Covino, S.; Götz, D.; Esposito, P. +4 more
GRB 041219A is one of the longest and brightest gamma-ray bursts (GRBs) ever observed. It was discovered by the INTEGRAL satellite, and thanks to a precursor happening about 300 s before the bulk of the burst, ground-based telescopes were able to catch the rarely observed prompt emission in the optical and in the near-infrared bands.
Here we …The environment and characteristics of low-redshift galaxies detected by the Herschel-ATLAS
Rodighiero, G.; Ivison, R. J.; Clements, D. L. +41 more
We investigate the ultraviolet and optical properties and environment of low-redshift galaxies detected in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) science demonstration data. We use the Sloan Digital Sky Survey seventh release and the Galaxy And Mass Assembly data base to select galaxies with ? mag in the redshift range 0.…