INTEGRAL: Science Highlights and Future Prospects

Winkler, Christoph; Diehl, R.; Ubertini, P.; Wilms, J.

doi:10.1007/s11214-011-9846-0

Cited by 47 publications

(46 citation statements)

References 121 publications

(118 reference statements)

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“…The last decade has witnessed an important advance in understanding high mass X-ray binaries (HMXBs), thanks to the discovery of Supergiant Fast X-ray Transients (SFXTs; Sguera et al 2005;Negueruela et al 2005) during INTE-GRAL (Winkler et al 2003(Winkler et al , 2011 monitoring observations of the Galactic plane at hard X-ray energies, above 20 keV.…”

Section: Introductionmentioning

confidence: 99%

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

Sidoli

Tiengo

Paizis

et al. 2017

ApJ

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We report the results of an XMM-Newton and NuSTAR coordinated observation of the Supergiant Fast Xray Transient (SFXT) IGR J11215-5952, performed on February 14, 2016, during the expected peak of its brief outburst, which repeats every ∼165 days. Timing and spectral analysis were performed simultaneously in the energy band 0.4-78 keV. A spin period of 187.0 (±0.4) s was measured, consistent with previous observations performed in 2007. The X-ray intensity shows a large variability (more than one order of magnitude) on timescales longer than the spin period, with several luminous X-ray flares which repeat every 2-2.5 ks, some of which simultaneously observed by both satellites. The broad-band (0.4-78 keV) time-averaged spectrum was well deconvolved with a double-component model (a blackbody plus a power-law with a high energy cutoff) together with a weak iron line in emission at 6.4 keV (equivalent width, EW, of 40±10 eV). Alternatively, a partial covering model also resulted in an adequate description of the data. The source time-averaged X-ray luminosity was 10 36 erg s −1 (0.1-100 keV; assuming 7 kpc). We discuss the results of these observations in the framework of the different models proposed to explain SFXTs, supporting a quasi-spherical settling accretion regime, although alternative possibilities (e.g. centrifugal barrier) cannot be ruled out.

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Section: Introductionmentioning

confidence: 99%

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

Sidoli

Tiengo

Paizis

et al. 2017

ApJ

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“…[1,2] Its unique payload comprises the imager IBIS, [3] the spectrometer SPI, [4,5] as well as the complementary X-ray and optical cameras JEM-X [6] and OMC. [7] Furthermore, the INTEGRAL Radiation Environment Monitor IREM [8] provides precise data on the local radiation environment around the spacecraft.…”

Section: Sa's International Gamma Ray Astrophysics Laboratory (Integrmentioning

confidence: 99%

“…However, to date INTEGRAL is still the most sensitive, accurate and advanced gamma ray observatory in space and the scientific return of INTEGRAL is excellent. [1,2] INTEGRAL has operated almost perfectly throughout the mission, with no significant unrecoverable failures, and its overall performance is still far above design specifications: all prime units are still in use maintaining full redundancy, no major failures have occurred and the degradation of spacecraft components is minimal. [9] The main challenge during the past years of INTEGRAL operations was to counteract the effects of the period of low perigee altitude and the associated impact by the passage of the satellite through the inner Van Allen proton belt.…”

Section: Sa's International Gamma Ray Astrophysics Laboratory (Integrmentioning

confidence: 99%

INTEGRAL revisits Earth - Low perigee effects on spacecraft components

Hübner¹

2012

SpaceOps 2012 Conference

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Since its launch in 2002, ESA's INTErnational Gamma-Ray Astrophysics Laboratory(INTEGRAL) has been observing astronomical objects simultaneously in gamma-rays, Xrays and visible light. Using its four instruments, it provides insight into the nature of sources of extremely high-energy radiation, and 9 years after its launch the scientific interest is still very high. The performance of INTEGRAL has far exceeded design specifications. To date, it is still the most sensitive gamma ray observatory in space, all prime units are still in use, no major failures have occurred and the degradation of spacecraft components is minimal. Last but not least, the nominal lifetime of two years has already been far exceeded, and the remaining fuel on board still allows for another decade of operations.Major challenges the mission faces are the orbital evolution and the aging of spacecraft components: on October 25th 2011, INTEGRAL reached the lowest perigee altitude since its launch. This resulted in both increased exposure to proton radiation during perigee passage and an increased heating of the spectrometer's cryocooler due to the Earth albedo, leading to a small reduction in payload performance. Furthermore, all electrical components will have reached their total dose qualification limit soon. This paper summarizes the effects of the period of low perigee altitude on the degradation of the materials and spacecraft components. Furthermore, it presents the associated countermeasures, operational strategies as well as the impact on the fuel consumption and the science. Finally, the prospects for future INTEGRAL operations are summarized along with the lessons learned from the period of low perigee.

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“…It is described in detail in Vedrenne et al (2003), pre-launch and initial in-flight calibrations are described in Attié et al (2003) and Roques et al (2003), respectively, and five years of spacecraft and instrument operations are reviewed in Fahmy et al (2008). The main scientific goals of the INTEGRAL space mission are (Winkler et al 2003(Winkler et al , 2011: a survey of the high-energy sky with particular attention to sources such as binary systems, active galaxies, and transients such as stellar explosions and outbursts, flares, and state transitions, and the study of cosmic nucleosynthesis using nuclear lines. The latter is a unique domain of SPI due to its spectral range and resolution (see review by Diehl 2013).…”

Section: Introductionmentioning

confidence: 99%

INTEGRAL/SPI γ-ray line spectroscopy

Diehl

Siegert

Greiner

et al. 2018

A&A

Self Cite

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Context. The space based γ-ray observatory INTEGRAL of the European Space Agency (ESA) includes the spectrometer instrument "SPI". This is a coded mask telescope featuring a 19-element Germanium detector array for high-resolution γ-ray spectroscopy, encapsulated in a scintillation detector assembly that provides a veto for background from charged particles. In space, cosmic rays irradiate spacecraft and instruments, which, in spite of the vetoing detectors, results in a large instrumental background from activation of those materials, and leads to deterioration of the charge collection properties of the Ge detectors. Aims. We aim to determine the measurement characteristics of our detectors and their evolution with time, that is, their spectral response and instrumental background. These incur systematic variations in the SPI signal from celestial photons, hence their determination from a broad empirical database enables a reduction of underlying systematics in data analysis. For this, we explore compromises balancing temporal and spectral resolution within statistical limitations. Our goal is to enable modelling of background applicable to spectroscopic studies of the sky, accounting separately for changes of the spectral response and of instrumental background. Methods. We use 13.5 years of INTEGRAL/SPI data, which consist of spectra for each detector and for each pointing of the satellite. Spectral fits to each such spectrum, with independent but coherent treatment of continuum and line backgrounds, provides us with details about separated background components. From the strongest background lines, we first determine how the spectral response changes with time. Applying symmetry and long-term stability tests, we eliminate degeneracies and reduce statistical fluctuations of background parameters, with the aim of providing a self-consistent description of the spectral response for each individual detector. Accounting for this, we then determine how the instrumental background components change in intensities and other characteristics, most-importantly their relative distribution among detectors. Results. Spectral resolution of Ge detectors in space degrades with time, up to 15% within half a year, consistently for all detectors, and across the SPI energy range. Semi-annual annealing operations recover these losses, yet there is a small long-term degradation. The intensity of instrumental background varies anti-correlated to solar activity, in general. There are significant differences among different lines and with respect to continuum. Background lines are found to have a characteristic, well-defined and long-term consistent intensity ratio among detectors. We use this to categorise lines in groups of similar behaviour. The dataset of spectral-response and background parameters as fitted across the INTEGRAL mission allows studies of SPI spectral response and background behaviour in a broad perspective, and efficiently supports precision modelling of instrumental background.

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INTEGRAL: Science Highlights and Future Prospects

Cited by 47 publications

References 121 publications

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

INTEGRAL revisits Earth - Low perigee effects on spacecraft components

INTEGRAL/SPI γ-ray line spectroscopy

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