Search Publications
Photometric redshifts in the Hubble Deep Fields: evolution of extinction and the star formation rate
Rowan-Robinson, Michael
Photometric redshifts are studied with a template approach using data from the Hubble Deep Field (HDF) North and South. The problem of aliasing in photometric redshift estimates is investigated in some detail and found not to be a significant problem if at least four photometric bands are available. The performance of the approach presented here a…
Hubble Space Telescope Observations of High-Velocity Lyα and Hα Emission from Supernova Remnant 1987A: The Structure and Development of the Reverse Shock
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +18 more
We present two-dimensional line profiles of high-velocity (~+/-12,000 km s-1) Lyα and Hα emission from supernova remnant 1987A obtained with the Space Telescope Imaging Spectrograph between 1997 September and 2001 September (days 3869-5327 after the explosion). This emission comes from hydrogen in the debris that is excited and ionized …
The Ionized Gas and Nuclear Environment in NGC 3783. III. Detection of a Decreasing Radial Velocity in an Intrinsic Ultraviolet Absorber
Kaiser, Mary Elizabeth; Brandt, W. N.; Kaspi, Shai +14 more
We report an intrinsic absorber with decreasing outflow velocity in the Seyfert 1 galaxy NGC 3783. This is the first detection of a change in radial velocity in an outflow associated with a Seyfert galaxy. These results are based on measurements from 18 observations with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, o…
XMM-Newton spectral analysis of the Pulsar Wind Nebula within the composite SNR G0.9+0.1
Decourchelle, A.; Warwick, R. S.; Porquet, D.
We present a study of the composite supernova remnant G0.9+0.1 based on observations by XMM-Newton. The EPIC spectrum shows diffuse X-ray emission from the region corresponding to the radio shell. The X-ray spectrum of the whole Pulsar Wind Nebula is well fitted by an absorbed power-law model with a photon index Gamma ~ 1.9 and a 2-10 keV luminosi…
The Red Giant Branch luminosity function bump
Salaris, M.; Recio-Blanco, A.; Zoccali, M. +6 more
We present observational estimates of the magnitude difference between the luminosity function red giant branch bump and the horizontal branch (Delta F555WbumpHB), and of star counts in the bump region (Rbump), for a sample of 54 Galactic globular clusters observed by the HST. The large sample of stars resolved in …
Measuring σ8 with Cluster Lensing: Biases from Unrelaxed Clusters
Smith, Graham P.; Smail, Ian; Kneib, Jean-Paul +3 more
We use gravitational lens models and X-ray spectral analysis of 10 X-ray-luminous galaxy clusters at z~=0.2 to study the impact of cluster substructure on attempts to normalize the matter power spectrum. We estimate that unrelaxed clusters are 30% hotter than relaxed clusters, causing σ8 to be overestimated by 20% if the cluster selecti…
A simultaneous XMM-Newton and BeppoSAX observation of the archetypal broad line Seyfert 1 galaxy NGC 5548
Perola, G. C.; Matt, G.; Reeves, J. N. +3 more
We report the spectral analysis of a long XMM-Newton observation of the well-studied, moderate luminosity broad line Seyfert 1 galaxy NGC 5548. The source was at an historically average brightness and we find the hard (3-10 keV) spectrum can be well fitted by a power law of photon index Γ~ 1.75, together with reflection. The only feature in the ha…
The System Parameters of DW Ursae Majoris
Knigge, C.; Dhillon, V. S.; Szkody, P. +8 more
We present new constraints on the system parameters of the SW Sextantis star DW Ursae Majoris, based on ultraviolet (UV) eclipse observations with the Hubble Space Telescope. Our data were obtained during a low state of the system, in which the UV light was dominated by the hot white dwarf (WD) primary. The duration of the WD eclipse allows us to …
Deuterium toward Two Milky Way Disk Stars: Probing Extended Sight Lines with the Far Ultraviolet Spectroscopic Explorer
Hoopes, Charles G.; Sembach, Kenneth R.; Hébrard, Guillaume +2 more
We have carried out an investigation of the abundance of deuterium along two extended sight lines through the interstellar medium (ISM) of the Galactic disk. The data include Far Ultraviolet Spectroscopic Explorer (FUSE) observations of HD 195965 (B1 Ib) and HD 191877 (B0 V), as well as Space Telescope Imaging Spectrograph (STIS) observations of H…
The Early Ultraviolet Evolution of the ONeMg Nova V382 Velorum 1999
Gehrz, Robert D.; Bond, Howard E.; Krautter, Joachim +7 more
We present a multiwavelength study of the ONeMg Galactic nova V382 Velorum 1999 using HST/STIS and FUSE ultraviolet spectra and comparisons with published ground-based optical spectra. We find a close match to the basic phenomenology of another well-studied ONeMg nova, V1974 Cygni (Nova Cyg 1992), in particular, to the spectral development through…