Search Publications
Optical and infrared observations of radioactive elements in supernovae
Sollerman, Jesper
At late phases the powering of supernova light curves is often provided by the decay of radioactive elements synthesized in the explosions. This is unambiguously revealed when the light curve decline follows the half-life time of the decaying elements, and the bolometric luminosity then directly provides the mass of ejected radioactive material. I…
HST NICMOS imaging of z∼2-3 radio-quiet quasars
Calzetti, D.; Lehnert, M.; Ridgway, S. +1 more
We will present the results of a NICMOS H-band imaging survey of a small sample of z∼2-3 radio-quiet quasars. We have resolved extension in at least four of five objects and find evidence for a wide range in the morphologies and magnitudes of these hosts. The host galaxy luminosities range from sub- L ∗ to about 4 L ∗, with m…
Spectral energy distributions of five FR I radio galaxies
Capetti, A.; Chiaberge, M.; Celotti, A. +2 more
We discuss the multi-wavelength properties of the radio galaxies 3C 31, 3C 264, 3C 270, 3C 465 and NGC 7052. The data have been deduced from observations with the VLBI/VLA arrays, HST and ROSAT. The SED of these sources, when compared with that of BL Lacs shows that beaming effects are important, but are not enough—in the simplest scenario—to expl…
Irradiation phenomena in young solar-type stars and the early solar system: X-ray observations and γ-ray constraints
Montmerle, Thierry
The high levels of X-ray flaring activity observed in young stars and protostars suggest correspondingly high levels of low-energy particle irradiation of their circumstellar disks, and hence of early solar system material like meteorites. We first briefly review the latest X-ray observational results obtained by Chandra and XMM-Newton on two 'typ…
Hubble space telescope observations of BL Lacertae environments
Urry, C. Megan; O'Dowd, Matthew; Scarpa, Riccardo +3 more
We analyze images of BL Lacertae objects obtained with the Hubble Space Telescope WFPC2 and the F814W filter. The nine objects cover a redshift range of 0.19 to 0.997. The relatively deep images are sufficient to detect galaxies at least one magnitude below MI* (-21.4) and in most cases to three magnitudes below M*. Galaxy enhancement o…
HST imaging of radio galaxies at /z=0.2: a comparison with quasar hosts and normal ellipticals
McLure, R. J.; Dunlop, J. S.; Hughes, D. H. +3 more
We summarise the results of our recently completed HST R-band study of low-redshift (0.1< z<0.25) FRII radio galaxies along with the host galaxies of quasars of similar redshifts. We find that, like radio galaxies, the hosts of radio-loud quasars and all but the least luminous radio-quiet quasars are massive elliptical galaxies with relative…
The nuclear dust disks of five nearby 3CR elliptical galaxies
Sparks, W. B.; Baum, S. A.; Biretta, J. A. +3 more
We present broad- and narrow-band WFPC2 images of the nuclear dust disks and rings of five low- z elliptical galaxies hosting 3C radio sources: NGC 383 (3C 31)/NGC 382, NGC 3862 (3C 264), NGC 4261 (3C 270), UGC 12064 (3C 449), and NGC 7720 (3C 465)/NGC 7720A. We detect resolved line emission in all the disks. In NGC 383, the line emission consists…
An HST emission-line imaging survey of 3CR radio galaxies
Sparks, W. B.; Macchetto, F.; McCarthy, P. J. +4 more
We present narrow-band images of sixty-four 3CR radio sources observed in lines of [OII] 3727 Å, [OIII] 5007 Å, and H α using the WFPC2 camera on-board HST. The images reveal a wide variety of emission lime morphologies, from compact nuclear regions to large-scale emission knots, filaments, and spiral-like structures. Many objects give evidence of…
Host galaxies and the unification of radio-loud AGN
Giavalisco, Mauro; Urry, C. Megan; O'Dowd, Matthew +4 more
Our HST WFPC2 survey of 110 BL Lac objects, from six complete X-ray-, radio-, and optically-selected catalogs, probes the host galaxies of low-luminosity radio sources in the redshift range 0< z<1.35. The host galaxies are luminous ellipticals, well matched in radio power and galaxy magnitude to FR I radio galaxies. Similarly, the host galax…
X-ray spectroscopy of supernova remnants
Ballet, Jean; Decourchelle, Anne
The new generation X-ray telescopes launched in 1999 ( Chandra and XMM-Newton) provide for the first time, good spatial and spectral resolution together, allowing to map emission lines of heavy elements in supernova remnants. In young supernova remnants this reflects nucleosynthesis in the progenitor, and gives access (in theory) to the absolute a…