RXTE monitoring of Centaurus A

Benlloch, S.; Rothschild, R. E.; Wilms, J.; Reynolds, C. S.; Heindl, W. A.; Staubert, R.

doi:10.1051/0004-6361:20010438

Cited by 16 publications

(29 citation statements)

References 36 publications

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“…The spectral slope is consistent with earlier measurements by BeppoSAX and RXTE, giving absorption values of N H ∼ 10 23 cm −2 and Γ = 1.80 above 3 keV (Grandi et al 2003;Benlloch et al 2001). The slope is slightly flatter than reported from early INTEGRAL measurements with Γ = 2.02 ± 0.03 (Soldi et al 2005), Γ = 1.94 ± 0.02 (Beckmann et al 2006), and Γ = 1.94 ± 0.07 (Rothschild et al 2006).…”

Section: Discussionsupporting

confidence: 91%

“…Only the data of JEM-X are significantly influenced by the intrinsic absorption, whereas for IBIS/ISGRI and SPI the absorption value was fixed to the average value of N H = 10 23 cm −2 (e.g. Grandi et al 2003;Benlloch et al 2001). An estimate of the turnover in the spectrum of Cen A can already be achieved by analysing the IBIS/ISGRI data alone.…”

Section: The Hard X-ray Spectrummentioning

confidence: 99%

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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: Discussionsupporting

confidence: 91%

Section: The Hard X-ray Spectrummentioning

confidence: 99%

The hard X-ray emission of Centaurus A

Beckmann

Jean

Lubiński

et al. 2011

A&A

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“…In the years preceeding the present observations, the instruments on BeppoSAX and RXTE viewed Cen A five times (Grandi et al 2003) and three times (Benlloch et al 2001), respectively. In the energy range above 3 keV, they found the spectrum to be characterized by an absorbed (N H ∼10 23 cm −2 ) power law (Γ=1.80).…”

Section: Previous Observationsmentioning

confidence: 78%

“…The strongest upper limits to date on the solid angle contributing to the reflection are Ω/2π < 0.05 from the combined RXTE observations (Benlloch et al 2001).…”

Section: Previous Observationsmentioning

confidence: 95%

“…The RXTE observations used the Proportional Counter Array (PCA; Jahoda et al 1996) and the High Energy X-ray Timing Experiment (HEXTE; Rothschild et al 1998). Table 1 gives the details of these three observations plus the previous three RXTE observations (Benlloch et al 2001). The INTEGRAL observations are essentially continuous due to the ∼72 hr elliptical orbit, while the RXTE observations are broken-up due to South Atlantic Anomaly passages, Earth-occults, and unavoidable slews to other targets for short periods of time.…”

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confidence: 99%

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INTEGRAL and RXTE Observations of Centaurus A

Rothschild¹,

Wilms²,

Tomsick³

et al. 2006

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INTEGRAL and RXTE performed three simultaneous observations of the nearby radio galaxy Centaurus A in March, 2004 January, and 2004 February with the goals of investigating the geometry and emission processes via the spectral/temporal variability of the X-ray/low energy gamma ray flux, and intercalibration of the INTEGRAL instruments with respect to those on RXTE. Cen A was detected by both sets of instruments from 3-240 keV. When combined with earlier archival RXTE results, we find the power law continuum flux and the line-of-sight column depth varied independently by 60% between 2000 January and 2003 March. Including the three archival RXTE observations, the iron line flux was essentially unchanging, and from this we conclude that the iron line emitting material is distant from the site of the continuum emission, and that the origin of the iron line flux is still an open question. Taking X-ray spectral measurements from satellite missions since 1970 into account, we discover a

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A study on the long term periodicities among the X‐ray binaries: Two new superorbital periods

Özdemir¹

2010

Astron Nachr

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Long term behaviours of a few selected X-ray binaries are studied on the basis of RXTE/ASM archive covering a period of ∼13 years of continuous X-ray data. Two new superorbital periods seem to be revealed for the GX354-0 and X Persei systems as 8.7 years and 345 days, respectively. Although the X Persei system has two strongest peaks in its power density spectrum at 15.7 years and at 345 days, the latter is much more plausible. The GX354-0 system also has few additional periodicities appeared in different time intervals.

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RXTE monitoring of Centaurus A

Cited by 16 publications

References 36 publications

The hard X-ray emission of Centaurus A

The hard X-ray emission of Centaurus A

INTEGRAL and RXTE Observations of Centaurus A

A study on the long term periodicities among the X‐ray binaries: Two new superorbital periods

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