Search Publications
Modelling galaxy and AGN evolution in the infrared: black hole accretion versus star formation activity
Pozzi, F.; Vignali, C.; Gruppioni, C. +1 more
We present a new backward evolution model for galaxies and active galactic nuclei (AGNs) in the infrared (IR). What is new in this model is the separate study of the evolutionary properties of different IR populations (i.e. spiral galaxies, starburst galaxies, low-luminosity AGNs, 'unobscured' type 1 AGNs and 'obscured' type 2 AGNs) defined throug…
New Constraints on Mass-dependent Disruption of Star Clusters in M51
Calzetti, Daniela; Schinnerer, Eva; Whitmore, Bradley C. +4 more
We use UBVI Hα images of the Whirlpool galaxy, M51, taken with the Advanced Camera for Surveys and WFPC2 cameras on the Hubble Space Telescope (HST) to select star clusters, and to estimate their masses and ages by comparing their observed colors with predictions from population synthesis models. We construct the mass function of intermediate-age …
Simulated spectral states of active galactic nuclei and observational predictions
Gierliński, Marek; Siemiginowska, Aneta; Sobolewska, Małgorzata A.
Active galactic nuclei (AGN) and galactic black hole binaries (GBHs) represent two classes of accreting black holes. They both contain an accretion disc emitting a thermal radiation, and a non-thermal X-ray emitting 'corona'. GBHs exhibit state transitions, and the spectral states are characterized by different luminosity levels and shapes of the …
On the run-out distance of geophysical gravitational flows: Insight from fluidized granular collapse experiments
Mangeney, A.; Lucas, A.; Roche, O. +1 more
We present the results of laboratory experiments on the emplacement of gravitational granular flows generated from axisymmetrical release of columns of fine (~ 75 µm) or coarse (~ 330 µm) particles initially fluidized with air. Internal friction is first negligible in the granular columns and then increases as pore pressure diffuses wi…
Measuring Turbulence in the Interstellar Medium by Comparing N(H I; Lyα) and N(H I; 21 cm)
Lockman, Felix J.; Wakker, Bart P.; Brown, Jonathan M.
We present a study of the small-scale structure of the interstellar medium (ISM) in the Milky Way. We used HST STIS data to measure N(H I) in a pencil beam toward 59 active galactic nuclei and compared the results with the values seen at 9'-36' resolution in the same directions using radio telescopes (Green Bank Telescope, Green Bank 140-ft, and L…
Multiwavelength campaign on Mrk 509. VI. HST/COS observations of the far-ultraviolet spectrum
Kaastra, J. S.; Kriss, G. A.; Arav, N. +15 more
We present medium-resolution (λ/Δλ ~ 20 000) ultraviolet spectra covering the 1155-1760 Å spectral range of the Seyfert 1 galaxy
Detection of Current Sheets and Magnetic Reconnections at the Turbulent Leading Edge of an Interplanetary Coronal Mass Ejection
Chian, Abraham C. -L.; Muñoz, Pablo R.
The relation between current sheets, turbulence, and magnetic reconnections at the leading edge of an interplanetary coronal mass ejection detected by four Cluster spacecraft on 2005 January 21 is studied. We report the observational evidence of two magnetically reconnected current sheets in the vicinity of a front magnetic cloud boundary layer wi…
Star Clusters in the Tidal Tails of Interacting Galaxies: Cluster Populations Across a Variety of Tail Environments
Bastian, N.; Konstantopoulos, I. S.; Gallagher, S. C. +17 more
We have searched for compact stellar structures within 17 tidal tails in 13 different interacting galaxies using F606W- and F814W-band images from the Wide Field Planetary Camera 2 on the Hubble Space Telescope. The sample of tidal tails includes a diverse population of optical properties, merging galaxy mass ratios, H I content, and ages. Combini…
Phase-resolved spectroscopic study of the isolated neutron star RBS 1223 (1RXS J130848.6+212708)
Werner, K.; Neuhäuser, R.; Schwope, A. D. +3 more
Aims: We constrain the mass-to-radius ratio of isolated neutron stars by performing a spin-phase resolved X-ray spectroscopic analysis.
Methods: We combined the data from all observations of RBS 1223 (1RXS J130848.6+212708) conducted by XMM-Newton EPIC pn with the same instrumental setup in 2003-2007 to form spin-phase resolved spectra. …
The star formation history of the Large Magellanic Cloud star cluster NGC 1751
Goudfrooij, Paul; Kozhurina-Platais, Vera; Rubele, Stefano +2 more
The HST/ACS colour-magnitude diagrams (CMDs) of the populous Large Magellanic Cloud (LMC) star cluster NGC 1751 present both a broad main-sequence turn-off and a dual clump of red giants. We show that the latter feature is real and associate it to the first appearance of electron degeneracy in the H-exhausted cores of the cluster stars. We then ap…