Search Publications
Probing the Coevolution of Supermassive Black Holes and Quasar Host Galaxies
Ho, Luis C.; Rix, Hans-Walter; Peng, Chien Y. +2 more
At low redshift, there are fundamental correlations between the mass of supermassive black holes (MBH) and the mass (Mbulge) and luminosity of the host galaxy bulge. We investigate the same relation at z>~1. Using virial mass estimates for 11 quasars at z>~2 to measure their black hole mass, we find that black holes at …
The multi-phase gaseous halos of star forming late-type galaxies. I. XMM-Newton observations of the hot ionized medium
Pietsch, W.; Dettmar, R. -J.; Rossa, J. +2 more
This study presents first results from an X-ray mini-survey carried out with XMM-Newton to investigate the diffuse Hot Ionized Medium in the halos of nine nearby star-forming edge-on spiral galaxies. Diffuse gaseous X-ray halos are detected in eight of our targets, covering a wide range of star formation rates from quiescent to starburst cases. Fo…
Nonthermal High-Energy Emission from Colliding Winds of Massive Stars
Reimer, A.; Reimer, O.; Pohl, M.
Colliding winds of massive star binary systems are considered as potential sites of nonthermal high-energy photon production. Motivated by the detection of synchrotron radio emission from the colliding wind location, we here investigate the properties of high-energy photon production in colliding winds of long-period WR+OB systems. Analytical form…
Cluster observations of reconnection due to the Kelvin-Helmholtz instability at the dawnside magnetospheric flank
Balogh, A.; Lavraud, B.; Kistler, L. M. +4 more
On 3 July 2001, the four Cluster satellites traversed along the dawnside magnetospheric flank and observed large variations in all plasma parameters. The estimated magnetopause boundary normals were oscillating in the z-direction and the normal component of the magnetic field showed systematic 2-3 min bipolar variations for 1 h when the IMF had a …
Evidence for a Polar Ethane Cloud on Titan
Baines, K. H.; Jaumann, R.; Clark, R. +11 more
Spectra from Cassini's Visual and Infrared Mapping Spectrometer reveal the presence of a vast tropospheric cloud on Titan at latitudes 51° to 68° north and all longitudes observed (10° to 190° west). The derived characteristics indicate that this cloud is composed of ethane and forms as a result of stratospheric subsidence and the particularly coo…
An XMM-Newton view of the young open cluster NGC 6231 - II. The OB star population
Gosset, E.; Nazé, Y.; Rauw, G. +2 more
In this second paper of the series, we pursue the analysis of the 180-ks XMM-Newton campaign towards the young open cluster NGC 6231 and we focus on its rich OB star population. We present a literature-based census of the OB stars in the field of view with more than one hundred objects, among which 30 per cent can be associated with an X-ray sourc…
A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume
Spencer, John R.; Kieffer, Susan W.; Lu, Xinli +3 more
We hypothesize that active tectonic processes in the south polar terrain of Enceladus, the 500-kilometer-diameter moon of Saturn, are creating fractures that cause degassing of a clathrate reservoir to produce the plume documented by the instruments on the Cassini spacecraft. Advection of gas and ice transports energy, supplied at depth as latent …
Clues to Nuclear Star Cluster Formation from Edge-on Spirals
Seth, Anil C.; Dalcanton, Julianne J.; Hodge, Paul W. +1 more
We find nine nuclear cluster candidates in a sample of 14 edge-on, late-type galaxies observed with the Hubble Space Telescope Advanced Camera for Surveys. These clusters have magnitudes (MI~-11) and sizes (reff~3 pc) similar to those found in previous studies of face-on, late-type spirals and dE galaxies. However, three of t…
The Spiderweb Galaxy: A Forming Massive Cluster Galaxy at z ~ 2
Pentericci, Laura; Franx, Marijn; Illingworth, Garth D. +11 more
We present a deep image of the radio galaxy MRC 1138-262 taken with the Hubble Space Telescope (HST) at a redshift of z=2.2. The galaxy is known to have properties of a cD galaxy progenitor and be surrounded by a 3 Mpc-sized structure, identified with a protocluster. The morphology shown on the new deep HST ACS image is reminiscent of a spider's w…
Explaining the Color Distributions of Globular Cluster Systems in Elliptical Galaxies
Yoon, Suk-Jin; Lee, Young-Wook; Yi, Sukyoung Ken
The colors of globular clusters in most large elliptical galaxies are bimodal. This is generally taken as evidence for the presence of two cluster subpopulations that have different geneses. However, here we find that, because of the nonlinear nature of the metallicity-to-color transformation, a coeval group of old clusters with a unimodal metalli…