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An XMM-Newton hard X-ray survey of ultraluminous infrared galaxies
Cappi, M.; Franceschini, A.; Bassani, L. +8 more
XMM-Newton observations of 10 ultraluminous infrared galaxies (ULIRGs) from a 200-ks mini-survey programme are reported. The aim is to investigate in hard X-rays a complete ULIRG sample selected from the bright IRAS 60-µm catalogue. All sources are detected in X-rays, five of which for the first time. These observations confirm that ULIRGs a…
Circumnuclear Dust in Nearby Active and Inactive Galaxies. II. Bars, Nuclear Spirals, and the Fueling of Active Galactic Nuclei
Pogge, Richard W.; Mulchaey, John S.; Martini, Paul +1 more
We present a detailed study of the relation between circumnuclear dust morphology, host-galaxy properties, and nuclear activity in nearby galaxies. We use our sample of 123 nearby galaxies with visible-near-infrared color maps from the Hubble Space Telescope to create well-matched, ``paired'' samples of 28 active and 28 inactive galaxies, as well …
Hubble Space Telescope ACS Coronagraphic Imaging of the Circumstellar Disk around HD 141569A
Ford, H. C.; Infante, L.; Zheng, W. +31 more
Multicolor coronagraphic images of the circumstellar disk around HD 141569A have been obtained with the Hubble Space Telescope Advanced Camera for Surveys. The B, V, and I images show that the disk's previously described multiple-ring structure is actually a continuous distribution of dust with a tightly wound spiral structure. Extending from the …
Clusters in the inner spiral arms of M 51: The cluster IMF and the formation history
Panagia, N.; Bastian, N.; Bik, A. +2 more
We present the results of an analysis of the HST-WFPC2 observations of the interacting galaxy M 51. From the observations in 5 broadband filters (UBVRI) and two narrowband filters (Hα and [OIII]) we study the cluster population in a region of 3.2 x 3.2 kpc2 in the inner spiral arms of M 51, at a distance of about 1 to 3 kpc from the nuc…
X-ray continuum variability of MCG-6-30-15
Nandra, K.; Vaughan, S.; Fabian, A. C.
This paper presents a comprehensive examination of the X-ray continuum variability of the bright Seyfert 1 galaxy MCG-6-30-15. The source clearly shows the strong, linear correlation between rms variability amplitude and flux first seen in Galactic X-ray binaries. The high-frequency power spectral density (PSD) of MCG-6-30-15 is examined in detail…
A Dynamical Model for the Globular Cluster G1
Baumgardt, Holger; Makino, Junichiro; Hut, Piet +2 more
We present a comparison between the observational data on the kinematical structure of G1 in M31, obtained with the Hubble Space Telescope Wide Field Planetary Camera 2 and Space Telescope Imaging Spectrograph instruments, and the results of dynamical simulations carried out using the special purpose computer GRAPE-6. We have obtained good fits fo…
Radio Emission from an Ultraluminous X-ray Source
Kaaret, Philip; Zezas, Andreas; Corbel, Stephane +1 more
The physical nature of ultraluminous x-ray sources is uncertain. Stellar-mass black holes with beamed radiation and intermediate black holes with isotropic radiation are two plausible explanations. We discovered radio emission from an ultraluminous x-ray source in the dwarf irregular galaxy NGC 5408. The x-ray, radio, and optical fluxes as well as…
Chemical sources of haze formation in Titan's atmosphere
Atreya, S. K.; Wilson, E. H.
A prominent feature of Titan's atmosphere is a thick haze region that acts as the end product of hydrocarbon and nitrile chemistry. Using a one-dimensional photochemical model, an investigation into the chemical mechanisms responsible for the formation of this haze region is conducted. The model derives profiles for Titan's atmospheric constituent…
X-Ray Emission from the Hot Interstellar Medium and Southwest Radio Lobe of the Nearby Radio Galaxy Centaurus A
Churazov, E.; Hardcastle, M. J.; Worrall, D. M. +5 more
We present results from two Chandra/ACIS-I observations and one XMM-Newton observation of X-ray emission from the interstellar medium (ISM) and the inner radio lobes of the nearby radio galaxy Centaurus A. The ISM has an average radial surface brightness profile that is well described by a β-model profile with index β=0.40+/-0.04 and a temperature…
On the Central Structure of M15
Baumgardt, Holger; Makino, Junichiro; Hut, Piet +2 more
We present a detailed comparison between the latest observational data on the kinematical structure of the core of M15, obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 instruments, and the results of dynamical simulations carried out using the special purpose GRAPE-6 computer. The obs…