Search Publications
X-ray and optical observations of M55 and NGC 6366: evidence for primordial binaries
Lewin, W. H. G.; Verbunt, F.; Pooley, D. +3 more
We present Chandra X-ray Observatory ACIS-S3 X-ray imaging observations and VLT/FORS2 and Hubble Space Telescope optical observations of two low-density Galactic globular clusters; NGC 6366 and M 55. We detect 16 X-ray sources with 0.5-6.0 keV luminosities above L_ {X}= 4 × 1030 erg s-1 within the half-mass radius of M 55, of…
On the absorption of X-ray bright broad absorption line quasars
Cappi, M.; Vignali, C.; Giustini, M.
Context: Most X-ray studies of broad absorption line quasars (BALQSOs) found significant (NH∼ 1022-24 cm-2) intrinsic column densities of gas absorbing an underlying typical power-law continuum emission, in agreement with expectations from radiatively driven accretion disk wind models. However, direct spectral anal…
Discovery of heavily-obscured AGN among seven INTEGRAL hard X-ray sources observed by Chandra
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +4 more
Aims: We identify hard X-ray sources discovered by the INTEGRAL all-sky survey. We complete identification of a unique sample of active galactic nuclei (AGN) selected in the hard X-ray band (17-60 keV) with minimal effects from absorption. Subsequently, we determine the fraction of obscured AGN in the local Universe.
Methods: We observed 7 INT…
Time evolution of the line emission from the inner circumstellar ring of SN 1987A and its hot spots
Lundqvist, P.; Spyromilio, J.; Gröningsson, P. +4 more
We present seven epochs between October 1999 and November 2007 of high resolution VLT/UVES echelle spectra of the ejecta-ring collision of SN 1987A. The fluxes of most of the narrow lines from the unshocked gas decreased by a factor of 2-3 during this period, consistent with the decay from the initial ionization by the shock break-out. However, [O…
The broad-band XMM-Newton and INTEGRAL spectra of bright type 1 Seyfert galaxies
de Rosa, A.; Walter, R.; Bird, A. J. +7 more
Aims: The 0.5-150 keV broad-band spectra of a sample of nine bright type 1 Seyfert galaxies are analyzed here. These sources have been discovered/detected by INTEGRAL and subsequently observed with XMM-Newton for the first time with high sensitivity below 10 keV. The sample, although small, is representative of the population of type 1 AGN which a…
INTEGRAL observations of Hercules X-1
Tsygankov, S.; Klochkov, D.; Santangelo, A. +6 more
Aims: We investigate the X-ray spectral and timing properties of the accreting X-ray pulsar Her X-1 observed with the INTEGRAL satellite in July-August 2005.
Methods: The data analyzed in this work cover a substantial part of one main-on state of the source. The short time scale pulse period development is measured. X-ray pulse profiles for di…
Suzaku broad-band spectroscopy of RX J1347.5-1145: constraints on the extremely hot gas and non-thermal emission
Yoshikawa, K.; Ota, N.; Komatsu, E. +6 more
Context: We present the results of our analysis of long Suzaku observations (149 ks and 122 ks for XIS and HXD, respectively) of the most X-ray luminous galaxy cluster, RX J1347.5-1145, at z=0.451.
Aims: To understand the gas physics of a violent, cluster merger, we study physical properties of the hot ( 20 keV) gas clump in the south-east (SE…
1RXS J173021.5-055933: a cataclysmic variable with a fast-spinning magnetic white dwarf
Mukai, K.; Haberl, F.; Gänsicke, B. T. +8 more
Aims:We present the first X-ray observations with the XMM-Newton and INTEGRAL satellites of the recently discovered cataclysmic variable 1RXS J173021.5-055933, together with simultaneous UV and coordinated optical photometry aiming at characterising its broad-band temporal and spectral properties and classifying this system as a magnetic one.
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Young stars and brown dwarfs surrounding Alnilam (ɛ Orionis) and Mintaka (δ Orionis)
Caballero, J. A.; Solano, E.
Aims: We look for new regions to search for substellar objects.
Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, were explored. The regions are very young (less than 10 Ma), have low extinction, and are neighbours to σ Orionis (~3 Ma), a young open cluster very…
Hadronic versus leptonic origin of the gamma-ray emission from supernova remnant RX J1713.7-3946
Völk, H. J.; Berezhko, E. G.
Aims: The hadronic vs. leptonic origin of the gamma-ray emission from the Supernova Remnant RX J1713.7-3946 is discussed both in the light of new observations and from a theoretical point of view.
Methods: The existing good spatial correlation of the gamma-ray emission and the nonthermal X-ray emission is analyzed theoretically. In addition, t…