Search Publications
A simple test for periodic signals in red noise
Vaughan, S.
We demonstrate a simple method for testing the significance of peaks in the periodogram of red noise data. The procedure was designed to test for spurious periodicities in X-ray light curves of active galaxies, but can be used quite generally to test for periodic components against a background noise spectrum assumed to have a power law shape. The…
Lower mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
Bouret, J. -C.; Hillier, D. J.; Lanz, T.
We have analyzed the far-ultraviolet spectrum of two Galactic O4 stars, the O4If+ supergiant HD 190429A and the O4V((f)) dwarf HD 96715, using archival FUSE and IUE data. We have conducted a quantitative analysis using the two NLTE model atmosphere and wind codes, tlusty and cmfgen, which incorporate a detailed treatment of NLTE metal line blanket…
Did most present-day spirals form during the last 8 Gyr?. A formation history with violent episodes revealed by panchromatic observations
Elbaz, D.; Cesarsky, C.; Flores, H. +3 more
Studies of distant galaxies have shown that ellipticals and large spirals (Schade et al. \cite{Schade99}, ApJ, 525, 31; Lilly et al. \cite{Lilly98}, ApJ, 500, 75) were already in place 8 Gyr ago, leading to a very modest recent star formation (Brinchmann & Ellis \cite{Brinchmann00}, ApJ, 536, L77) in intermediate mass galaxies (3-30 × 101…
X-ray obscuration and obscured AGN in the local universe
Perola, G. C.; Guainazzi, M.; Matt, G.
We discuss the X-ray properties of 49 local (z<0.035) Seyfert 2 galaxies with HST/WFC2 high-resolution optical coverage. It includes the results of 26 still unpublished Chandra and XMM-Newton observations, which yield 25 (22) new X-ray detections in the 0.5-2 keV (2-10 keV) energy band. Our sample covers a range in the 2-10 keV observed flux, F…
The structural and scaling properties of nearby galaxy clusters. I. The universal mass profile
Arnaud, M.; Pointecouteau, E.; Pratt, G. W.
We present the integrated mass profiles for a sample of ten nearby (z<~0.15), relaxed galaxy clusters, covering a temperature range of [2-9] keV, observed with XMM-Newton. The mass profiles were derived from the observed gas density and temperature profiles under the hypothesis of spherical symmetry and hydrostatic equilibrium. All ten mass pro…
Spectroscopy of polycyclic aromatic hydrocarbons and very small grains in photodissociation regions
Joblin, C.; Rapacioli, M.; Boissel, P.
We have coupled a singular value decomposition method with a Monte Carlo search algorithm to analyse the mid-infrared ISOCAM spectral maps of photodissociation regions (PDRs) in NGC 7023 and ρ Oph-SR3.Three different spectra and their associated spatial distribution were extracted from this analysis. It is shown that they can be associated with po…
INTEGRAL observations of recurrent fast X-ray transient sources
Hill, A. B.; Bird, A. J.; Ubertini, P. +9 more
Fast X-ray Transients (FXTs) are believed to be non-recurrent bright X-ray sources lasting less than a day and occuring at serendipitous positions, they can best be detected and discovered by instruments having a sufficiently wide field of view and high sensitivity. The IBIS/ISGRI instrument onboard INTEGRAL is particularly suited to detect new or…
Evidence for a co-moving sub-stellar companion of GQ Lup
Wuchterl, G.; Neuhäuser, R.; Guenther, E. W. +3 more
We present a companion of the ≤2 Myr young classical T Tauri star GQ Lup in the Lupus star forming region at 140 ± 50 pc from imaging, astrometry, and spectroscopy. With direct K-band imaging using VLT/NACO, we detected an object 6 mag fainter than GQ Lup located 0.7'' west of it. Compared to images obtained 2 to 5 years earlier with Subaru/CIAO a…
ISM properties in low-metallicity environments. III. The spectral energy distributions of II Zw 40, He 2-10 and NGC 1140
Bernard, J. -P.; Madden, S. C.; Galliano, F. +2 more
We present new 450 and 850 µm SCUBA data and 1.3 mm MAMBO data of the dwarf galaxies II Zw 40, He 2-10 and NGC 1140. Additional ISOCAM, IRAS as well as ground based data are used to construct the observed mid-infrared to millimeter spectral energy distribution of these galaxies. These spectral energy distributions are modeled in a self-consi…
The star cluster population of M 51. II. Age distribution and relations among the derived parameters
Bastian, N.; Gieles, M.; de Grijs, R. +2 more
We use archival Hubble Space Telescope observations of broad-band images from the ultraviolet (F255W-filter) through the near infrared (NICMOS F160W-filter) to study the star cluster population of the interacting spiral galaxy M 51. We obtain age, mass, extinction, and effective radius estimates for 1152 star clusters in a region of ~7.3 × 8.1 kpc…