Transdisziplinarität in der Philosophie – die Arbeiten von Mittelstraß und Gibbons et al.

Büchner, Stefanie

doi:10.1007/978-3-531-94115-8_2

Cited by 1 publication

(9 citation statements)

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“…The source and background spectra employed in this work are a selected subsample of the spectra extracted by Brightman et al (2014) analyzed by Buchner et al (2014) from the CDF-S 4Ms, which is based on the source catalog of Rangel et al (2013) (hereafter R13), using data reduction methods following the work of Laird et al (2009). The background extraction region around any given source is constructed so that it contains at least 100 counts after masking all the other sources out.…”

Section: Data and Sample Selectionmentioning

confidence: 99%

“…Our sources are hard band (2-7 keV) selected and as in Rangel et al (2013) are considered significant if the Poisson probability that the observed counts are a background fluctuation is less than 4 × 10 −6 . We used spectroscopic (preferably) or photometric redshifts from the work of Hsu et al (2014), following Buchner et al (2014). In addiction to this, we restrict the analysis to sources with redshift lower than 4, both due to limitations in models and because above this redshift the sources are few and of low signal-to-noise ratio.…”

Section: Data and Sample Selectionmentioning

confidence: 99%

“…We employ the Bayesian X-ray Analysis (BXA, Buchner et al 2014) software to fit the X-ray spectra and compare models. BXA is a Bayesian framework to determine the best-fitting models and their parameter constraints for X-ray spectra.…”

Section: Model Comparison Overviewmentioning

confidence: 99%

“…When applying the C-statistic we can not subtract the background, so we model this simultaneously with the source spectrum. We use the Chandra background model from Buchner et al (2014) (see Figure 1).…”

Section: Model Comparison Overviewmentioning

confidence: 99%

“…In this work, we aim to investigate the presence of the relativistic broadening of the Fe Kα in the spectra of the AGN population as observed with Chandra using a different approach, specifically by using the Bayesian X-ray analysis (BXA) spectral fitting method (Buchner et al 2014). This allows information to be extracted from the individual spectra even if of low signal-to-noise ratio, and the results combined to make inferences about the population as a whole.…”

Section: Introductionmentioning

confidence: 99%

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Relativistic reflection from accretion disks in the population of Active Galactic Nuclei at z=0.5–4

Baronchelli

Nandra

Buchner

2018

Monthly Notices of the Royal Astronomical Society

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We report the detection of relativistically broadened iron Kα emission in the X-ray spectra of AGN detected in the 4Ms CDF-S. Using the Bayesian X-ray analysis (BXA) package, we fit 199 hard band (2-7 keV) selected sources in the redshift range z=0.5-4 with three models: (i) an absorbed power-law, (ii) the first model plus a narrow reflection component, and (iii) the second model with an additional relativistic broadened reflection. The Bayesian evidence for the full sample of sources selects the model with the additional broad component as being 10 5 times more probable to describe the data better than the second model. For the two brightest sources in our sample, CID 190 (z=0.734) and CID 104 (z=0.543), BXA reveals the relativistic signatures in the individual spectra. We estimate the fraction of sources containing a broad component to be 54 +35 −37 % (107/199 sources). Considering that the low signal-to-noise ratio of some spectra prevents the detection of the broad iron Kα line, we infer an intrinsic fraction with broad emission of around two thirds. The detection of relativistic signatures in the X-ray spectra of these sources suggests that they are powered by a radiatively efficient accretion disk. Preliminary evidence is found that the spin of the black hole is high, with a maximally spinning Kerr BH model (a=1) providing a significantly better fit than a Schwarzschild model (a=0). Our analysis demonstrate the potential of X-ray spectroscopy to measure this key parameter in typical SMBH systems at the peak of BH growth.

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