Search Publications
Suzaku reveals X-ray continuum piercing the nuclear absorber in Markarian 231
Maiolino, R.; Fiore, F.; Piconcelli, E. +3 more
We report the results from a 2011 Suzaku observation of the nearby low-ionization broad absorption line (BAL) quasar/ULIRG Markarian 231 (Mrk 231). These data reveal that the X-ray spectrum has undergone a large variation from the 2001 XMM-Newton and BeppoSAX observations. We interpret this finding according to a scenario whereby the X-ray continu…
On the nature of the brightest globular cluster in M81
Bressan, A.; Torres-Papaqui, J. P.; Mayya, Y. D. +5 more
We analyse the photometric, chemical, star formation history and structural properties of the brightest globular cluster (GC) in M81, referred to as GC1 in this work, with the intention of establishing its nature and origin. We find that it is a metal-rich ([Fe/H] = -0.60 ± 0.10), alpha-enhanced ([α/Fe] ∼ 0.20 ± 0.05), core-collapsed (core radius …
Three-dimensional Keplerian orbit-superposition models of the nucleus of M31
Magorrian, J.; Brown, C. K.
We present three-dimensional eccentric disc models of the nucleus of M31, modelling the disc as a linear combination of thick rings of massless stars orbiting in the potential of a central black hole. Our models are non-parametric generalizations of the parametric models of Peiris and Tremaine. The models reproduce well the observed Wide Field Pla…
The preferentially magnified active nucleus in IRAS F10214+4724 - II. Spatially resolved cold molecular gas
Heywood, I.; Deane, R. P.; Rawlings, S. +1 more
We present Jansky Very Large Array observations of the cold (CO (1→0)) molecular gas in IRAS F10214+4724, a lensed ultraluminous infraRed galaxy (ULIRG) at z = 2.3 with an obscured active nucleus. The galaxy is spatially and spectrally well resolved in the CO (1→0) emission line. The total intensity and velocity maps reveal a reasonably ordered sy…
X-ray variability and energy spectra from NGC 5408 X-1 with XMM-Newton
Wolter, A.; Belloni, T. M.; Caballero-García, M. D.
The notion of source states characterizing the X-ray emission from black hole binaries has revealed to be a very useful tool to disentangle the complex spectral and aperiodic phenomenology displayed by those classes of accreting objects. We seek to use the same tools for ultraluminous X-ray (ULX) sources. We analysed the data from the longest obse…
The Herschel view of the environment of the radio galaxy 4C+41.17 at z = 3.8
Meisenheimer, K.; Stern, D.; Greve, T. R. +16 more
We present Herschel observations at 70, 160, 250, 350 and 500 µm of the environment of the radio galaxy 4C+41.17 at z = 3.792. About 65 per cent of the extracted sources are securely identified with mid-infrared sources observed with the Spitzer Space Telescope at 3.6, 4.5, 5.8, 8 and 24 µm. We derive simple photometric redshifts, also…
An O2 If*/WN6 star caught in the act in a compact H II region in the starburst cluster NGC 3603
Roman-Lopes, A.
In this paper, we report on the discovery of an O2 If*/WN6 star probably still partially embedded in its parental cocoon in the starburst cluster NGC 3603. From the observed size of the associated compact H II region, it has been possible to derive a probable dynamic age of no more than 600 000 yr. Using the computed visual extinction value A…
Orbital motion of the binary brown dwarf companions HD 130948 BC around their host star
Neuhäuser, R.; Schmidt, T. O. B.; Ginski, C. +2 more
Evolutionary models and mass estimates for brown dwarfs remain uncertain, hence determining the masses of brown dwarfs by model-independent methods is important to test and constrain such theories. Following the orbital motion of brown dwarf companions around their primaries gives us the opportunity to dynamically calculate the masses of these sys…
The Herschel Virgo Cluster Survey - XIV. Transition-type dwarf galaxies in the Virgo cluster
Zibetti, Stefano; De Looze, Ilse; Baes, Maarten +19 more
We use dust scaling relations to investigate the hypothesis that Virgo cluster transition-type dwarfs are infalling star-forming field galaxies, which is argued based on their optical features (e.g. discs, spiral arms and bars) and kinematic properties similar to late-type galaxies. After their infall, environmental effects gradually transform the…
Calibration of RAVE distances to a large sample of Hipparcos stars
Francis, Charles
A magnitude-limited population of 18 808 Hipparcos stars is used to calibrate distances for 52 794 RAdial Velocity Experiment (RAVE) stars, including dwarfs, giants and pre-main-sequence stars. I give treatments for a number of types of bias affecting calculation, including bias from the non-linear relationship between the quantity of interest (e.…