158 research outputs found
Discovery of X-ray pulsations in the Be/X-ray binary LS992/ RX J0812.4-3114
We report on the discovery of X-ray pulsations from the Be/X-ray system LS
992/RX J0812.4-3114 during an RXTE observation. From a timing analysis of the
source we obtained a barycentric pulse period of 31.8851 \pm 0.0004 s. The
pulse profile is highly structured and departs from a pure sinusoidal shape. It
shows a sharp dip that may indicate absorption by the accretion flow. The
energy spectrum from 3-30 keV can be fitted by a power-law model with an
exponential cut-off in accordance with other X-ray pulsars. The X-ray
luminosity is estimated to be in the energy
range 3-30 keV, assuming a distance of .Comment: 5 pages, 6 fgures, 2 tables, to appear in MNRA
Discovery of two new persistent Be/X-ray pulsar systems
We present RXTE observations of two recently identified massive X-ray
binaries. RX J0440.9+4431/BSD 24-491 and RX J1037.5-564/LS 1698 are confirmed
as accreting Be/X-ray systems following the discovery of X-ray pulsations, with
barycentric pulse periods of 202.50.5 s and 8602 s respectively. The
X-ray spectral analysis shows that the energy spectra of the pulsars can be
represented by a power-law, modified at low energy by an absorption component
and at high energy by a cut-off. Very weak Fe lines may be present. Both
sources appear to display a low cut-off energy when compared to typical X-ray
pulsars, low X-ray variability (factor of < 10), and no dependence of the X-ray
spectrum with energy. Given the similarity of these X-ray properties with those
of the other persistent BeXRB pulsars, 4U0352+309/X Per and RX J0146.9+6121/LS
I +61 235, we suggest that RX J0440.9+4431/BSD 24-491 and RX J1037.5-564/LS
1698 are also members of this subclass.Comment: 8 pages 7 figures, accepted for publication in MNRA
The Be X-ray Binary Outburst Zoo
Be X-ray binaries are among the best known transient high-energy sources.
Their outbursts are commonly classified into a simple scheme of 'normal' and
'giant' outbursts, but a closer look shows that actual outbursts do not always
follow this simple scheme. Recent data show a variety of properties, like
pre-flares, shifts of the outburst peaks with respect to the periastron,
multi-peaked outbursts etc. We present results from a systematic study of a
large number of outbursts monitored by various space missions, comparing
outburst properties and their relation to system parameters and current
theoretical understanding.Comment: Proceedings of "An INTEGRAL view of the high-energy sky (the first 10
years)" the 9th INTEGRAL Workshop, October 15-19, 2012, Paris, France, in
Proceedings of Science (INTEGRAL 2012), Eds. A. Goldwurm, F. Lebrun and C.
Winkler, (http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=176), id
PoS(INTEGRAL 2012)01
A quantitative explanation of the radio--X-ray correlation in black-hole X-ray binaries
The observed correlation between the radio and X-ray fluxes in the hard state
of black-hole X-ray binaries (BHXRBs) has been around for more than two
decades. It is currently accepted that the hard X-rays in BHXRBs come from
Comptonization in the corona and the radio emission from the relativistic jet
(Lorentz ), which is a narrow structure of a few at
its base. The relativistic jet and the corona, however, are separate entities
with hardly any communication between them, apart from the fact that both are
fed from the accreting matter. It is also widely accepted that the accretion
flow around black holes in BHXRBs consists of an outer thin disk and an inner
hot flow. From this hot inner flow, an outflow emanates in the hard and
hard-intermediate states of the source. By considering Compton up-scattering of
soft disk photons in the outflow (i.e., in the outflowing corona, which is a
wider structure, tens to hundreds of at its base, with low Lorentz gamma)
as the mechanism that produces the hard X-ray spectrum, we have been able to
explain quantitatively a number of observed correlations. Here, we demonstrate
that this outflowing corona can also explain quantitatively the observed radio
- X-ray correlation. In addition, we make the following theoretical predictions
for GX 339-4: 1) the radio flux in the hard and hard-intermediate states should
be a bell-shaped curve as a function of the photon-number spectral index Gamma,
2) the radio - X-ray correlation should break down when the source moves from
the hard to the hard-intermediate state and instead the radio flux should first
increase sharply in the hard-intermediate state and then decrease also sharply,
in a very narrow range of the X-ray flux, and 3) the X-ray polarization will be
parallel to the outflow in the hard state and perpendicular to it in the
hard-intermediate one.Comment: Accepted for publication in A&
Highly Magnetized Accreting Pulsars: Are There Accreting Magnetars?
2S 0114+650, GX 301-2, IGR J16358-4726, X Per, 4U 2206+54, SXP 1062, and 3A 1954+319 are thought to possess high magnetic elds. They have recently been named accreting magnetars, or highly magnetized accreting pulsars. In this work their properties are reviewed. Within the context of their observational properties (mainly from INTEGRAL data), and the recent models of accretion onto highly magnetized neutron stars, their similarities and dierences are analyzed. The aim is to find a common framework to understand the evolution (in terms of past and present history) of these sources, and to establish the basis of a possible new kind of accreting sources. Two of these sources, namely X Per and 4U 2206+54, contain a massive main-sequence companion, while the rest are supergiant X-ray binaries or symbiotic systems. The variety of astrophysical scenarios represented by this set is wide, therefore the study of these systems is also important in order to establish commonalities between the dierent types of accreting X-ray pulsars and to study the possible evolutionary links between them
The BluenetCat : the catalan reference network for the knowledge transfer in blue economy
The blue economy is an essential sector to accelerate the green transition and to comply with the most important European and international regulations (e.g., the Blue Growth Strategy and the European Green Deal, and the UN Sustainable Development Goals). In Catalonia, the blue economy accounts for about 5.8% of total employment and 3.4% of GVA. Due to the crucial location of the region within the Mediterranean Basin, and its scientific and technological capacity, Catalonia may be among the leaders in terms of innovation in blue economy, with huge potential to export innovation and to provide the whole society with huge benefits and positive impacts. In 2018, Catalonia was among the first regions in Europe to adopt a maritime strategy according to the EU directives and regulations. Within the Catalonian Maritime Strategy, the technological transfer of innovation in blue economy plays a key role. Thus, the BlueNetCat (âXarxa dâR+D+I MarĂtima de Catalunyaâ in Catalan, www.bluenetcat.eu) was designed as a tool to foster the technological transfer - in all the disciplines affecting the blue economy sectors - from the Catalan universities and research centers toward the market and the society. Nowadays, the BlueNetCat (âXarxa dâR+D+I MarĂtima de Catalunyaâ in Catalan) is an open innovation multidisciplinary community, accounting for more than 700 researchers, trainees, and technicians. The network is constantly growing and currently is composed by 67 research groups belonging to 5 Catalan universities (University of Barcelona, Autonomous University of Barcelona, Universitat PolitĂšcnica de Catalunya, University of Girona, Rovira i Virgili University) and 2 research institutions (the Spanish National Research Council, CSIC, with three different research centers, and the Institute of Agrifood Research and Technology, IRTA).Peer Reviewe
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