Analysis of extremely low signal-to-noise ratio data from INTEGRAL/PICsIT

Lubiński, P.

doi:10.1051/0004-6361:200810897

Cited by 20 publications

(16 citation statements)

References 38 publications

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“…Data reduction was performed using the Offline Scientific Analysis (OSA) package version 9.0 provided by the ISDC . The PICsIT data analysis followed the procedure described in Lubiński (2009). The different instruments were not always switched on simultaneously.…”

Section: Discussionmentioning

confidence: 99%

The hard X-ray emission of Centaurus A

Beckmann

Jean

Lubiński

et al. 2011

A&A

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Context. The radio galaxy Cen A has been detected all the way up to the TeV energy range. This raises the question about the dominant emission mechanisms in the high-energy domain. Aims. Spectral analysis allows us to put constraints on the possible emission processes. Here we study the hard X-ray emission, in order to distinguish between a thermal and a non-thermal inverse Compton process. Methods. Using hard X-ray data provided by INTEGRAL, we determined the cut-off of the power-law spectrum in the hard X-ray domain (3−1000 keV). In addition, INTEGRAL data are used to study the spectral variability. The extended emission detected in the gamma-rays by Fermi/LAT is investigated using the data of the spectrometre SPI in the 40−1000 keV range. Results. The hard X-ray spectrum of Cen A shows a significant cut-off at energies E C = 434 +106 −73 keV with an underlying power-law of photon index Γ = 1.73 ± 0.02. A more physical model of thermal Comptonisation (compPS) gives a plasma temperature of kT e = 206 ± 62 keV within the optically thin corona with Compton parameter y = 0.42 +0.09 −0.06 . The reflection component is significant at the 1.9σ level with R = 0.12 +0.09 −0.10 , and a reflection strength R > 0.3 can be excluded on a 3σ level. Time resolved spectral studies show that the flux, absorption, and spectral slope varied in the range f 3−30 keV = 1.2−9.2 × 10 −10 erg cm −2 s −1 , N H = 7−16 × 10 22 cm −2 , and Γ = 1.75−1.87. Extending the cut-off power-law or the Comptonisation model to the gamma-ray range shows that they cannot account for the high-energy emission. On the other hand, a broken or curved power-law model can also represent the data, therefore a non-thermal origin of the X-ray to GeV emission cannot be ruled out. The analysis of the SPI data provides no sign of significant emission from the radio lobes and gives a 3σ upper limit of f 40−1000 keV < ∼ 1.1 × 10 −3 ph cm −2 s −1 . Conclusions. While gamma-rays, as detected by CGRO and Fermi, are caused by non-thermal (jet) processes, the main process in the hard X-ray emission of Cen A is still not unambiguously determined, since it is either dominated by thermal inverse Compton emission or by non-thermal emission from the base of the jet.

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Section: Discussionmentioning

confidence: 99%

The hard X-ray emission of Centaurus A

Beckmann

Jean

Lubiński

et al. 2011

A&A

Self Cite

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“…Data reduction was performed using the Offline Scientific Analysis (OSA) package version 9.0. The PICsIT data analysis followed the procedure described in Lubinski et al [15]. The different instruments were not always switched on simultaneously.…”

Section: Discussionmentioning

confidence: 99%

Extended emission and spectral break in Cen A

Beckmann¹,

Jean²,

Lubiński³

et al. 2011

Proceedings of 8th INTEGRAL Workshop “The Restless Gamma-Ray Universe” — PoS(INTEGRAL 2010)

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The radio galaxy Cen A has been detected all the way up to the TeV energy range. This raises the question about the dominant emission mechanisms in the high-energy domain. Spectral analysis allows us to put constraints on the possible emission processes. Here we study the hard X-ray emission, in order to distinguish between a thermal or non-thermal inverse Compton process. The hard X-ray spectrum of Cen A shows a significant cut-off at energies E C = 434 −0.10 . Extending this model to the gamma-ray range shows that a different physical component is responsible for the high-energy emission. The analysis of the SPI data provides no sign of significant emission from the radio lobes and gives a 3" upper limit of f 40−1000 keV < 1.1 × 10 −3 ph cm −2 s −1 . We find though some indication of emission near to the northern lobe of Cen A which we investigate in more detail.

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“…Therefore, an alternative software for the PICsIT detector was developed [4]. A main ingredient of the new method is a direct handling of the probability density functions (PDFs) for both background and source.…”

Section: Integral/picsit Detectormentioning

confidence: 99%

“…The third element of the new software is a careful modelling of the instrumental background, based on studies of the background variability over a single satellite revolution period. The PICSIT spectral extraction software allowed for a detection of 12 sources listed in [4]. Until now only the results for Cyg X-1 were used for a scientific analysis [5,14], however, the tests show that the number of detected sources should exceed 20.…”

Section: Integral/picsit Detectormentioning

confidence: 99%

“…Until now only the results for Cyg X-1 were used for a scientific analysis [5,14], however, the tests show that the number of detected sources should exceed 20. The method described in [4] assumes that there is only one detectable source in the field of view of the instrument. This is a good approximation because the detectable celectial objects are usually well separated.…”

Section: Integral/picsit Detectormentioning

confidence: 99%

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Soft gamma-ray emission from the V404 Cygni outburst observed with INTEGRAL/PICsIT

Lubiński¹,

Bazzano²,

Natalucci³

et al. 2017

Proceedings of 11th INTEGRAL Conference Gamma-Ray Astrophysics in Multi-Wavelength Perspective — PoS(INTEGRAL2016)

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V404 Cygni during its 2015 outburst was the brightest source ever observed by INTEGRAL in the soft gamma-ray band. This made possible to detect the source with the IBIS high energy detector PICsIT in many single pointings (≈1 h long) allowing to study the evolution of the gamma-ray emission over the whole event period. In general, the PICsIT flux in the 255-340 keV band correlates with the hard X-ray flux measured by INTEGRAL/ISGRI, although we observe a saturation of the gamma-ray emission from the source. The spectra extracted for several short periods of the outburst were modelled with a Comptonization model. The plasma temperature remains stable despite a variation of the Compton parameter. We found a strong Compton reflection and a hint for a non-thermal emission occurring during some phases of the outburst. Our preliminary analysis do not show a presence of the positron annihilation line in the V404 Cygni spectra from the 2015 outburst.

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Analysis of extremely low signal-to-noise ratio data from INTEGRAL/PICsIT

Cited by 20 publications

References 38 publications

The hard X-ray emission of Centaurus A

The hard X-ray emission of Centaurus A

Extended emission and spectral break in Cen A

Soft gamma-ray emission from the V404 Cygni outburst observed with INTEGRAL/PICsIT

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