The variable X-ray spectrum of Markarian 766

Miller, L.; Turner, T. J.; Reeves, J. N.; George, I. M.; Kraemer, S. B.; Wingert, Brian

doi:10.1051/0004-6361:20066548

Cited by 106 publications

(170 citation statements)

References 52 publications

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“…In fact, several authors have demonstrated that accretion disk winds/outflows might well imprint also other spectral signatures in the X-ray spectra of AGNs besides blue-shifted Fe K absorption lines (e.g., Pounds & Reeves 2009, and references therein). For instance, Sim et al (2008) and Sim et al (2010) have been able to successfully reproduce the 2−10 keV spectra of two bright sources of our sample in which the detection of strong blue-shifted Fe K absorption lines in their XMM-Newton spectra were already reported, namely Mrk 766 (from Miller et al 2007) and PG 1211+143 (from Pounds et al 2003a), using their AGN accretion disk wind model. Notably, the authors have been able to account for both emission and absorption features in a physically self-consistent way.…”

Section: Discussionmentioning

confidence: 53%

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Evidence for ultra-fast outflows in radio-quiet AGNs

Tombesi

Cappi²,

Reeves

et al. 2010

A&A

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647

750

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Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims. The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods. We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results. We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10 −8 , and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10 −7 . We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to ∼0.3c, with a peak and mean value at ∼0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different XMM-Newton observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-shifts of the sources and the lines blue-shifted velocities, ruling out any systematic contamination by local absorption. If we define ultra-fast outflows (UFOs) those highly ionized absorbers with outflow velocities higher than 10 4 km s −1 , then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ∼35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of the absorbers is consequently estimated to be in the range C ∼ 0.4−0.6, thereby implying large opening angles. Conclusions. From our systematic X-ray spectral analysis on a large sample of radio-quiet AGNs we have been able to clearly assess the global veracity of the blue-shifted Fe K absorption lines at E > 7 keV and to overcome their publication bias. These lines indicate that UFOs are a rather ...

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Section: Discussionmentioning

confidence: 53%

“…We interpreted such features as blue-shifted Fe XXVI Lyα absorption lines. The presence of the first one at a rest-frame energy of ∼7.3 keV has already been suggested by Miller et al (2007) and Turner et al (2007).…”

Section: Appendix B: Notes On Single Sourcesmentioning

confidence: 54%

Evidence for ultra-fast outflows in radio-quiet AGNs

Tombesi

Cappi²,

Reeves

et al. 2010

A&A

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647

750

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“…This strongly suggests that the absorption material could be observed in the spectrum through Fe Kshell absorption lines from Fe xxv and Fe xxvi (e.g., Sim et al 2008;Schurch et al 2009;Sim et al 2010), in complete agreement with our detection of UFOs. In particular, Sim et al (2008) and Sim et al (2010) used their accretion disk wind model to successfully reproduce the 2-10 keV spectra of two bright radioquiet AGNs in which strong blueshifted Fe K absorption lines were detected in their XMM-Newton spectra, namely, Mrk 766 (from Miller et al 2007) and PG 1211+143 (from Pounds et al 2003). Notably, the authors have been able to account for both emission and absorption features in a physically self-consistent way and demonstrated that accretion disk winds/outflows might well imprint also other spectral signatures in the X-ray spectra of AGNs (e.g., Pounds & Reeves 2009 and references therein).…”

Section: Physical Properties Of Ultra-fast Outflowsmentioning

confidence: 99%

DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITHSUZAKU

Tombesi

Sambruna

Reeves

et al. 2010

ApJ

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180

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We present the results of a uniform and systematic search for blueshifted Fe K absorption lines in the X-ray spectra of five bright broad-line radio galaxies observed with Suzaku. We detect, for the first time in radio-loud active galactic nuclei (AGNs) at X-rays, several absorption lines at energies greater than 7 keV in three out of five sources, namely, 3C 111, 3C 120, and 3C 390.3. The lines are detected with high significance according to both the F-test and extensive Monte Carlo simulations. Their likely interpretation as blueshifted Fe xxv and Fe xxvi K-shell resonance lines implies an origin from highly ionized gas outflowing with mildly relativistic velocities, in the range v 0.04-0.15c. A fit with specific photoionization models gives ionization parameters in the range log ξ 4-5.6 erg s −1 cm and column densities of N H 10 22 -10 23 cm −2 . These characteristics are very similar to those of the ultra-fast outflows (UFOs) previously observed in radio-quiet AGNs. Their estimated location within ∼0.01-0.3 pc of the central super-massive black hole suggests a likely origin related with accretion disk winds/outflows. Depending on the absorber covering fraction, the mass outflow rate of these UFOs can be comparable to the accretion rate and their kinetic power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, these UFOs can play a significant role in the expected feedback from the AGN to the surrounding environment and can give us further clues on the relation between the accretion disk and the formation of winds/jets in both radio-quiet and radio-loud AGNs.

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“…Among the possible physical interpretations of these features are an origin in the accretion disc (e.g. Reeves et al 2001;Pounds et al 2001;Miller et al 2007) or produced in photoionised circumnuclear matter (e.g. Bianchi & Matt 2002;Bianchi et al 2005); • Fe I 6.4 keV Compton shoulder (G i ).…”

Section: Spectral Modelmentioning

confidence: 99%

FERO: Finding extreme relativistic objects

Pérez

Longinotti

Guainazzi

et al. 2010

A&A

121

107

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Context. Accretion models predict that fluorescence lines broadened by relativistic effects should arise from reflection of X-ray emission onto the inner region of the accretion disc surrounding the central black hole of active galactic nuclei (AGN). The theory behind the origin of relativistic lines is well established, and observational evidence from a moderate number of sources seems to support the existence of these lines. Aims. The aim of this work is to establish the fraction of AGN with relativistic Fe K α lines, and study possible correlations with source physical properties.Methods. An XMM-Newton collection of 149 radio-quiet Type 1 AGN has been systematically and uniformly analysed in order to search for evidence of a relativistically broadened Fe K α line. To enable statistical studies, an almost complete, flux-limited subsample of 31 sources has been defined by selecting the FERO sources observed by the RXTE all-sky Slew Survey with a count rate in the 3-8 keV energy band greater than 1 cts/sec. The 2-10 keV spectra of the FERO sources where compared with a complex model including most of the physical components observed in the X-ray spectra of Seyfert galaxies: a power law primary continuum modified by nonrelativistic Compton reflection and warm absorption, plus a series of narrow Fe line reflection features. Results. The observed fraction of sources in the flux-limited sample that show strong evidence of a relativistic Fe K α line is 36%. This number can be interpreted as a lower limit to the fraction of sources that present a relativistic broad Fe K α line in the wider AGN population. The average line equivalent width (EW) is of the order of 100 eV. The outcome of the fit yields an average disc inclination angle of 28 ± 5 • and an average power-law index of the radial disc emissivity law of 2.4 ± 0.4. The spin value is well constrained only in 2 cases ; in the rest of the cases, whenever a constraint can be placed, it always implies the rejection of the static black hole solution. The Fe K α line EW does not correlate with disc parameters or with system physical properties, such as black hole mass, accretion rate, and hard X-ray luminosity.

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The variable X-ray spectrum of Markarian 766

Cited by 106 publications

References 52 publications

Evidence for ultra-fast outflows in radio-quiet AGNs

Evidence for ultra-fast outflows in radio-quiet AGNs

DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITHSUZAKU

FERO: Finding extreme relativistic objects

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