Search Publications
Evidence for a Supermassive Black Hole in the S0 Galaxy NGC 3245
Filippenko, Alexei V.; Ho, Luis C.; Rix, Hans-Walter +3 more
The S0 galaxy NGC 3245 contains a circumnuclear disk of ionized gas and dust with a radius of 1.1" (110 pc), making it an ideal target for dynamical studies with the Hubble Space Telescope (HST). We have obtained spectra of the nuclear disk with the Space Telescope Imaging Spectrograph, using a 0.2" wide slit at five parallel positions. Measuremen…
The Diversity of High- and Intermediate-Velocity Clouds: Complex C versus IV Arch
Richter, Philipp; Tripp, Todd M.; Jenkins, Edward B. +5 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS) observations of interstellar ultraviolet absorption lines in the Galactic high-velocity cloud Complex C and the Intermediate-Velocity Arch (IV Arch) in the direction of the quasar PG 1259+593 (l=120.6d, b=+58.1d). Absorption lines from C II, N …
Hemispheric Helicity Trend for Solar Cycle 23
Pevtsov, Alexei A.; Canfield, Richard C.; Latushko, Sergei M.
Applying the same methods we used in solar cycle 22, we study active region vector magnetograms, full-disk X-ray images, and full-disk line-of-sight magnetograms to derive the helicity of solar magnetic fields in the first 4 years of solar cycle 23. We find that these three data sets all exhibit the same two key tendencies-significant scatter and …
The Variable Diffuse Continuum Emission of Broad-Line Clouds
Goad, Michael R.; Korista, Kirk T.
We investigate the wavelength-dependent intensity and reverberation properties of the UV-optical diffuse continuum emission expected from broad emission line gas. The ``locally optimally emitting clouds'' picture is adopted, with the cloud distribution functions in gas density and distance from the ionizing source determined by a fit to the mean U…
A NICMOS imaging study of high-z quasar host galaxies
Baum, Stefi A.; O'Dea, Christopher P.; Dunlop, James S. +4 more
We present the first results from a major Hubble Space Telescope programme designed to investigate the cosmological evolution of quasar host galaxies from µ z≃ 2r to the present day. Here we describe J and H-band NICMOS imaging of two quasar samples at redshifts of 0.9 and 1.9 respectively. Each sample contains equal numbers of radio-loud an…
The Importance of Einstein Rings
Keeton, C. R.; Kochanek, C. S.; McLeod, B. A.
We develop a theory of Einstein rings and demonstrate it using the infrared Einstein ring images of the quasar host galaxies observed in PG 1115+080, B1608+656, and B1938+666. The shape of an Einstein ring accurately and independently determines the shape of the lens potential and the shape of the lensed host galaxy. We find that the host galaxies…
XMM-Newton observation of the Coma Galaxy cluster. The temperature structure in the central region
Altieri, B.; Aghanim, N.; Arnaud, M. +8 more
We present a temperature map and a temperature profile of the central part (r < 20' or 1/4 virial radius) of the Coma cluster. We combined 5 overlapping pointings made with XMM/EPIC/MOS and extracted spectra in boxes of 3.5'x3.5'. The temperature distribution around the two central galaxies is remarkably homogeneous (r<10'), contrary to prev…
The XMM-Newton Serendipitous Survey. I. The role of XMM-Newton Survey Science Centre
Valtchanov, I.; Pietsch, W.; Read, A. M. +46 more
This paper describes the performance of XMM-Newton for serendipitous surveys and summarises the scope and potential of the XMM-Newton Serendipitous Survey. The role of the Survey Science Centre (SSC) in the XMM-Newton project is outlined. The SSC's follow-up and identification programme for the XMM-Newton serendipitous survey is described together…
Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer
Kruk, J. W.; Shull, J. M.; Sembach, K. R. +16 more
The neutral hydrogen (H I) and ionized helium (He II) absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar HE2347-4342 in the 1000 to 1187 angstrom band at a resolving power of 15,000. We resolve the He II Lyman α…
Broadband Observations of the Afterglow of GRB 000926: Observing the Effect of Inverse Compton Scattering
Piro, L.; Frontera, F.; Price, P. A. +23 more
GRB 000926 has one of the best-studied afterglows to date, with multiple X-ray observations, as well as extensive multifrequency optical and radio coverage. Broadband afterglow observations, spanning from X-ray to radio frequencies, provide a probe of the density structure of the circumburst medium, as well as of the ejecta energetics, geometry, a…