324 research outputs found
XMM-Newton monitoring of X-ray variability in the quasar PKS 0558-504
We present the temporal analysis of X-ray observations of the radio-loud
Narrow-Line Seyfert 1 galaxy (NLS1) PKS 0558-504 obtained during the XMM-Newton
Calibration and Performance Verification (Cal/PV) phase. The long term light
curve is characterized by persistent variability with a clear tendency for the
X-ray continuum to harden when the count rate increases. Another strong
correlation on long time scales has been found between the variability in the
hard band and the total flux. On shorter time scales the most relevant result
is the presence of smooth modulations, with characteristic time of ~ 2 hours
observed in each individual observation. The short term spectral variability
turns out to be rather complex but can be described by a well defined pattern
in the hardness ratio-count rate plane.Comment: 6 pages, 7 figures, accepted for publication in A&A special issue on
first results from XM
The on-ground acquisition and data analysis system for the PDS detector on board the SAX satellite
The Phoswich Detection System (PDS) is the high-energy
(15–300 keV) instrument on board the Italian-Dutch X-ray astronomy satellite SAX. Functional tests were carried on at BICRON (Newbury, Ohio, USA) and at LABEN (Vimodrone, Italy). Full ground calibrations have been performed between the end of 1994 and the beginning of 1995. We describe in the following the system that we used to acquire and analyse the data coming from the PDS experiment during the ground tests and calibrations. It will be used to store and maintain data during both the pre-operational and the operational phases. In a previous report (DAL FIUME D., FRONTERA F., ORLANDINI M. and TRIFOGLIO M., AIP Conf. Proc., 61 (1994) 395) we described the general architecture of the data analysis system. In this report we give a detailed description of the entire system, including the hardware and software developed by LABEN to acquire data during on-ground tests. A complete description of the different modules, user interface, inter-process communications, analysis and display tools are presented.
Current status of the project is discussed
Gamma-ray observations of Cygnus X-1 above 100 MeV in the hard and soft states
We present the results of multi-year gamma-ray observations by the AGILE
satellite of the black hole binary system Cygnus X-1. In a previous
investigation we focused on gamma-ray observations of Cygnus X-1 in the hard
state during the period mid-2007/2009. Here we present the results of the
gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 carried out
for which includes a remarkably prolonged `soft state' phase (June 2010 -- May
2011). Previous 1--10 MeV observations of Cyg X-1 in this state hinted at a
possible existence of a non-thermal particle component with substantial
modifications of the Comptonized emission from the inner accretion disk. Our
AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1,
provide a significant upper limit for gamma-ray emission above 100 MeV of
F_soft < 20 x 10^{-8} ph/cm^2/s, excluding the existence of prominent
non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We
discuss theoretical implications of our findings in the context of high-energy
emission models of black hole accretion. We also discuss possible gamma-ray
flares detected by AGILE. In addition to a previously reported episode observed
by AGILE in October 2009 during the hard state, we report a weak but important
candidate for enhanced emission which occurred at the end of June 2010
(2010-06-30 10:00 - 2010-07-02 10:00 UT) exactly in coincidence with a
hard-to-soft state transition and before an anomalous radio flare. An appendix
summarizes all previous high-energy observations and possible detections of
Cygnus X-1 above 1 MeV.Comment: 16 pages, 12 figures, 1 table, accepted for publication in Ap
CIWS-FW: a Customizable InstrumentWorkstation Software Framework for instrument-independent data handling
The CIWS-FW is aimed at providing a common and standard solution for the
storage, processing and quick look at the data acquired from scientific
instruments for astrophysics. The target system is the instrument workstation
either in the context of the Electrical Ground Support Equipment for
space-borne experiments, or in the context of the data acquisition system for
instrumentation. The CIWS-FW core includes software developed by team members
for previous experiments and provides new components and tools that improve the
software reusability, configurability and extensibility attributes. The CIWS-FW
mainly consists of two packages: the data processing system and the data access
system. The former provides the software components and libraries to support
the data acquisition, transformation, display and storage in near real time of
either a data packet stream and/or a sequence of data files generated by the
instrument. The latter is a meta-data and data management system, providing a
reusable solution for the archiving and retrieval of the acquired data. A
built-in operator GUI allows to control and configure the IW. In addition, the
framework provides mechanisms for system error and logging handling. A web
portal provides the access to the CIWS-FW documentation, software repository
and bug tracking tools for CIWS-FW developers. We will describe the CIWS-FW
architecture and summarize the project status.Comment: Accepted for pubblication on ADASS Conference Serie
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