Search Publications
Average hard X-ray emission from NS LMXBs: observational evidence of different spectral states in NS LMXBs
Titarchuk, L.; Frontera, F.; Goldoni, P. +9 more
Aims.We studied and compared the long-term average hard X-ray (>20 keV) spectra of a sample of twelve bright low-mass X-ray binaries hosting a neutron star (NS). Our sample comprises the six well studied Galactic Z sources and six Atoll sources, four of which are bright (“GX”) bulge sources while two are weaker ones in the 2-10 keV range (H 175…
Young star cluster complexes in NGC 4038/39. Integral field spectroscopy using VIMOS-VLT
Bastian, N.; Maraston, C.; Kissler-Patig, M. +1 more
We present the first results of a survey to obtain Integral Field Spectroscopy of merging galaxies along the Toomre Sequence. In the present work, we concentrate on the star cluster complexes in the Antennae galaxies (NGC 4038/39) in the overlap region as well as the nuclear region of NGC 4038. Using optical spectroscopy we derive the extinction, …
Infrared photometry and evolution of mass-losing AGB stars. I. Carbon stars revisited
Ciprini, S.; Guandalini, R.; Busso, M. +2 more
As part of a reanalysis of galactic Asymptotic Giant Branch (AGB) stars at infrared (IR) wavelengths, we discuss a sample (357) of carbon stars for which mass loss rates, near-IR photometry and distance estimates exist. For 252 sources we collected mid-IR fluxes from the MSX (6C) and the ISO-SWS catalogues. Most stars have spectral energy distribu…
uvby-β photometry of high-velocity and metal-poor stars. XI. Ages of halo and old disk stars
Moitinho, A.; Schuster, W. J.; Parrao, L. +2 more
New uvby-β data are provided for 442 high-velocity and metal-poor stars; 90 of these stars have been observed previously by us, and 352 are new. When combined with our previous two photometric catalogues, the data base is now made up of 1533 high-velocity and metal-poor stars, all with uvby-β photometry and complete kinematic data, such as proper …
Constraining the population of 6 ⪉ {z} ⪉ 10 star-forming galaxies with deep near-IR images of lensing clusters
Kneib, J. -P.; Schaerer, D.; Pelló, R. +2 more
We present the first results of our deep survey of lensing clusters aimed at constraining the abundance of star-forming galaxies at z∼6-10, using lensing magnification to improve the search efficiency and subsequent spectroscopic studies. Deep near-IR photometry of two lensing clusters (A1835 and AC114) was obtained with ISAAC/VLT. These images, c…
INTEGRAL observations of the blazar 3C 454.3 in outburst
Maraschi, L.; Tagliaferri, G.; Ghisellini, G. +22 more
In Spring 2005, the blazar 3C 454.3 underwent a dramatic outburst at all wavelengths from mm to X-rays. This prompted INTEGRAL observations, accomplished in 15-18 May 2005. The source was detected by the INTEGRAL instruments from 3 to 200 keV in a bright state (∼ 5 × 10-10 erg s-1 cm-2), at least a factor of 2-3 hi…
First observation of Mars with XMM-Newton. High resolution X-ray spectroscopy with RGS
Holmström, M.; Gunell, H.; Burwitz, V. +7 more
In the first observation of Mars with XMM-Newton, on 20-21 November 2003, this planet is clearly detected as an X-ray source. High resolution X-ray spectroscopy with the Reflection Grating Spectrometer (RGS) confirms that the X-ray radiation from Mars is composed of two different components: one due to fluorescent scattering of solar X-rays in its…
The broad-band spectrum of Cygnus X-1 measured by INTEGRAL
Goldoni, P.; Rodriguez, J.; Foschini, L. +9 more
The INTEGRAL satellite extensively observed the black hole binary Cygnus X-1 from 2002 November to 2004 November during calibration, open time and core program (Galactic Plane Scan) observations. These data provide evidence for significant spectral variations over the period. In the framework of the accreting black hole phenomenology, the source w…
Unveiling the nature of INTEGRAL objects through optical spectroscopy. III. Observations of seven southern sources
Palazzi, E.; Masetti, N.; Charles, P. A. +9 more
Context: . The detection, thanks to the INTEGRAL satellite, of a number of new hard X-ray sources calls for the identification of their nature by means of observations at longer wavelengths. Aims. In our continuing campaign to identify longer-wavelength counterparts of these newly-discovered hard X-ray sources detected by INTEGRAL, we observed the…
Nucleonic gamma-ray production in Vela X
Santangelo, A.; Aharonian, F.; Horns, D. +2 more
Context. The recently discovered extended very high energy gamma-ray (E>0.1~TeV=1011 eV) emission from at least three pulsar wind nebula systems (MSH 15-52, G18.0-07, and Vela X) could be hinting at a possibly new class of objects which is called in the following "TeV plerions". In some of these systems, particle acceleration could b…