Search Publications
Dynamical modelling of luminous and dark matter in 17 Coma early-type galaxies
Saglia, R. P.; Thomas, D.; Thomas, J. +5 more
Dynamical models for 17 early-type galaxies in the Coma cluster are presented. The galaxy sample consists of flattened, rotating as well as non-rotating early-types including cD and S0 galaxies with luminosities between MB = -18.79 and -22.56. Kinematical long-slit observations cover at least the major-axis and minor-axis and extend to …
Evolution of the Frequency of Luminous (>=L*V) Close Galaxy Pairs at z < 1.2 in the COSMOS Field
Sanders, D. B.; Kartaltepe, J. S.; Murayama, T. +8 more
We measure the fraction of luminous galaxies in pairs at projected separations of 5-20 kpc out to z=1.2 in the Cosmic Evolution Survey (COSMOS) field using ACS images and photometric redshifts derived from an extensive multiwavelength data set. Analysis of a complete sample of 106,188 galaxies more luminous than MV=-19.8 (~L*…
The Bullet Cluster 1E0657-558 evidence shows modified gravity in the absence of dark matter
Brownstein, J. R.; Moffat, J. W.
A detailed analysis of the 2006 November 15 data release X-ray surface density Σ-map and the strong and weak gravitational lensing convergence κ-map for the Bullet Cluster 1E0657-558 is performed and the results are compared with the predictions of a modified gravity (MOG) and dark matter. Our surface density Σ-model is computed using a King β-mod…
X-ray emission from T Tauri stars and the role of accretion: inferences from the XMM-Newton extended survey of the Taurus molecular cloud
Audard, M.; Güdel, M.; Briggs, K. R. +2 more
Context: T Tau stars display different X-ray properties depending on whether they are accreting (classical T Tau stars; CTTS) or not (weak-line T Tau stars; WTTS). X-ray properties may provide insight into the accretion process between disk and stellar surface.
Aims: We use data from the XMM-Newton Extended Survey of the Taurus molecular cloud…
Star Cluster Demographics. I. A General Framework and Application to the Antennae Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Chandar, Rupali
We present a framework for understanding the demographics of star cluster systems and develop a toy model that incorporates a universal initial power-law mass function, selected formation histories, selected disruption laws, and a convolution with common artifacts and selection effects found in observational data. A wide variety of observations ca…
Eruptions arising from tidally controlled periodic openings of rifts on Enceladus
Helfenstein, P.; Bills, B. G.; Hurford, T. A. +2 more
In 2005, plumes were detected near the south polar region of Enceladus, a small icy satellite of Saturn. Observations of the south pole revealed large rifts in the crust, informally called `tiger stripes', which exhibit higher temperatures than the surrounding terrain and are probably sources of the observed eruptions. Models of the ultimate inter…
The XMM-Newton Wide-Field Survey in the COSMOS Field. III. Optical Identification and Multiwavelength Properties of a Large Sample of X-Ray-Selected Sources
Finoguenov, A.; Taniguchi, Y.; Salvato, M. +31 more
We present the optical identification of a sample of 695 X-ray sources detected in the first 1.3 deg2 of the COSMOS XMM-Newton survey, down to a 0.5-2 keV (2-10 keV) limiting flux of ~10-15 erg cm-2 s-1 (~5×10-15 erg cm-2 s-1). In order to identify the correct optical cou…
The White Dwarf Cooling Sequence of NGC 6397
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +10 more
We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC 6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 mag in depth, with an apparent cutoff at magnitude F814W~27.6. We demonstrate, using both artificial star tests and the detectabil…
On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM-Newton
Guainazzi, Matteo; Bianchi, Stefano
We present results of a high-resolution soft X-ray (0.2-2 keV) spectroscopic study of a sample of 69 nearby obscured active galactic nuclei (AGNs) observed with the reflection grating spectrometer (RGS) onboard XMM-Newton. This is the largest sample ever studied with this technique so far. The main conclusions of our study can be summarized as fol…
Suzaku Observations of the Hard X-Ray Variability of MCG -6-30-15: the Effects of Strong Gravity around a Kerr Black Hole
Fabian, Andrew C.; Kunieda, Hideyo; Haba, Yoshito +21 more
Suzaku has, for the first time, enabled the hard X-ray variability of the Seyfert 1 galaxy MCG -6-30-15 to be measured. The variability in the 14-45keV band, which is dominated by a strong reflection hump, is quenched relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-l…