Search Publications
Cosmological parameters from supernova observations: A critical comparison of three data sets
Choudhury, T. R.; Padmanabhan, T.
We extend our previous analysis of cosmological supernova type Ia data \cite{pc03} to include three recent compilation of data sets. Our analysis ignores the possible correlations and systematic effects present in the data and concentrates mostly on some key theoretical issues. Among the three data sets, the first set consists of 194 points obtain…
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 It includes the results of 26 still unpublished Chandra and XMM-Newton observations, which yield 25 (22) new X-ray detections in the 0.5-2 keV (2-10 keV) energy band.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…
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…
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…
Molecular gas in NUclei of GAlaxies (NUGA). IV. Gravitational torques and AGN feeding
Hunt, L. K.; Schinnerer, E.; Combes, F. +2 more
We discuss the efficiency of stellar gravity torques as a mechanism to account for the feeding of the central engines of four low luminosity Active Galactic Nuclei (AGN): NGC 4321 (HII nucleus/LINER), NGC 4826 (HII nucleus/LINER), NGC 4579 (LINER 1.9/Seyfert 1.9) and NGC 6951 (Seyfert 2). These galaxies have been observed as part of the NUclei of …
Properties of Lyα emitters around the radio galaxy MRC 0316 257,
Pentericci, L.; Röttgering, H. J. A.; Miley, G. K. +9 more
Observations of the radio galaxy MRC 0316 257 at z = 3.13 and the surrounding field are presented. Using narrow- and broad-band imaging obtained with the VLT, 77 candidate Lyα emitters with a rest-frame equivalent width of >15 Å were selected in a ∼ 7´ × 7´ field around the radio galaxy. Spectroscopy of 40 candidate emitters resulted in the dis…
Sub-arcsec imaging of the AB Aur molecular disk and envelope at millimeter wavelengths: a non Keplerian disk
Guilloteau, S.; Dutrey, A.; Piétu, V.
We present sub-arcsecond images of AB Auriga obtained with the IRAM Plateau de Bure interferometer in the isotopologues of CO, and in continuum at 3 and 1.3 mm. These observations allow us to trace the structure of the circumstellar material of
VLT spectroscopy of globular cluster systems. II. Spectroscopic ages, metallicities, and [ α/Fe] ratios of globular clusters in early-type galaxies
Saglia, R. P.; Thomas, D.; Bender, R. +5 more
An analysis of ages, metallicities, and [ α/Fe] ratios of globular cluster systems in early-type galaxies is presented, based on Lick index measurements summarized in Puzia et al. (2004, A&A, 415, 123, Paper I of this series). In the light of calibration and measurement uncertainties, age-metallicity degeneracy, and the relative dynamic range …
Hierarchical star formation in M 51: star/cluster complexes
Bastian, N.; Gieles, M.; Lamers, H. J. G. L. M. +1 more
We report on a study of young star cluster complexes in the spiral galaxy M 51. Recent studies have confirmed that star clusters do not form in isolation, but instead tend to form in larger groupings or complexes. We use HST broad and narrow band images (from both WFPC2 and ACS), along with BIMA-CO observations to study the properties and investig…