Active galaxy 4U 1344-60: did the relativistic line disappear?

Svoboda, Jiří; Bianchi, S.; Guainazzi, M.; Matt, Giorgio; Piconcelli, E.; Karas, V.; Dovčiak, Michal

doi:10.1051/0004-6361/201219500

Cited by 3 publications

(3 citation statements)

References 59 publications

(79 reference statements)

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“…Unusually flat spectral slopes have been often found to be due to a partially-covering ionised absorber (see, e.g., Piconcelli et al 2004;Mathur et al 2009;Svoboda et al 2012). As the next step, we therefore employed a partially-covering ionised absorption to model the absorption features in the spectra.…”

Section: Modelling the Complex Absorptionmentioning

confidence: 99%

An X-ray variable absorber within the broad line region in Fairall 51

Svoboda

Guainazzi

Longinotti

et al. 2015

A&A

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Context. Fairall 51 is a polar-scattered Seyfert 1 galaxy, a type of active galaxy believed to represent a bridge between unobscured type-1 and obscured type-2 objects. Fairall 51 has shown complex and variable X-ray absorption, but little is known about its origin. Aims. In our research, we observed Fairall 51 with the X-ray satellite Suzaku in order to constrain a characteristic time scale of its variability. Methods. We performed timing and spectral analysis of four observations separated by 1.5, 2, and 5.5 day intervals. Results. We found that the 0.5-50 keV broadband X-ray spectra are dominated by a primary power-law emission (with the photon index ∼2). This emission is affected by at least three absorbers with different ionisations (log ξ ≈ 1-4). The spectrum is shaped further by a reprocessed emission, possibly coming from two regions, the accretion disc and a more distant scattering region. The accretion disc emission is smeared by the relativistic effects, from which we measured the spin of the black hole as a ≈ 0.8 ± 0.2. We found that most of the spectral variability can be attributed to the least ionised absorber whose column density changed by a factor of two between the first (highest-flux) and the last (lowest-flux) observation. Conclusions. A week-long scale of the variability indicates that the absorber is located at the distance ≈0.05 pc from the centre, i.e., in the broad line region.

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Section: Modelling the Complex Absorptionmentioning

confidence: 99%

An X-ray variable absorber within the broad line region in Fairall 51

Svoboda

Guainazzi

Longinotti

et al. 2015

A&A

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“…The broad component of the Fe Kα line can vary quite significantly over time (e.g. Iwasawa et al 1996;deMarco et al 2009;Svoboda et al 2012), but it has been difficult to determine the nature of the variability given detector limitations.…”

Section: A Ripple Effect In the Broad Fekα Line Componentmentioning

confidence: 99%

Ripple effects and oscillations in the broad Fe Kα line as a probe of massive black hole mergers

McKernan¹,

Ford²,

Kocsis³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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When a sufficiently massive satellite (or secondary) black hole is embedded in a gas disk around a (primary) supermassive black hole, it can open an empty gap in the disk. A gap-opening secondary close to the primary will leave an imprint in the broad component of the Fe Kα emission line, which varies in a unique and predictable manner. If the gap persists into the innermost disk, the effect consists of a pair of dips in the broad line which ripple blue-ward and red-ward from the line centroid energy respectively, as the gap moves closer to the primary. This ripple effect could be unambiguously detectable and allow an electromagnetic monitoring of massive black hole mergers as they occur. As the mass ratio of the secondary to primary black hole increases to q 0.01, we expect the gap to widen, possibly clearing a central cavity in the inner disk, which shows up in the broad Fe Kα line component. If the secondary stalls at 10 2 r g in its in-migration, due to low co-rotating gas mass, a detectable ripple effect occurs in the broad line component on the disk viscous timescale as the inner disk drains and the outer disk is dammed. If the secondary maintains an accretion disk within a central cavity, due to dam bursting or leakage, a periodic 'see-saw' oscillation effect is exhibited in the observed line profile. Here we demonstrate the range of ripple effect signatures potentially detectable with Astro-H and IXO/Athena, and oscillation effects potentially detectable with XMM-Newton or LOFT for a wide variety of merger and disk conditions, including gap width (or cavity size), disk inclination angle and emissivity profile, damming of the accretion flow by the secondary, and a mini-disk around the satellite black hole. A systematic study of ripple effects would require a telescope effective area substantially larger than that planned for IXO/Athena. Future mission planning should take this into account. Observations of the ripple effect and periodic oscillations can be used to provide an early warning of gravitational radiation emission from the AGN. Once gravitational waves consistent with massive black hole mergers are detected, an archival search for the FeKα ripple effect or periodic oscillations will help in localizing their origin.

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“…Since the radio lobes of Centaurus B are extended over almost the whole Suzaku CCD chip, it is difficult to extract background information from the data. Hence, we also analyze the Suzaku data for 4U 1344-60 (Observation ID 705058010; see also Svoboda et al (2012)), which is located ∼ 14 ′ away from Centaurus B. We assume that the diffuse X-ray backgrounds are the same between these data given the proximity.…”

Section: Suzaku Datamentioning

confidence: 99%

Fermi-LAT andSuzakuobservations of the radio galaxy Centaurus B

Katsuta

Tanaka

Stawarz

et al. 2013

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Centaurus B is a nearby radio galaxy positioned in the southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months of accumulated Fermi-LAT data of the γ-ray counterpart of the source initially reported in the 2nd Fermi-LAT catalog, and of newly acquired Suzaku X-ray data. We confirm its detection at GeV photon energies and analyze the extension and variability of the γ-ray source in the LAT dataset, in which it appears as a steady γ-ray emitter. The X-ray core of Centaurus B is detected as a bright source of a continuum radiation. We do not detect, however, any diffuse X-ray emission from the known radio lobes, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. Two scenarios that connect the X-ray and γ-ray properties are considered. In the first one, we assume that the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. In this case, modeling the inverse-Compton emission shows that the observed γ-ray flux of the source may in principle be produced within the lobes. This association would imply that efficient in-situ acceleration of the radiating electrons is occurring and that the lobes are dominated by the pressure from the relativistic particles. In the second scenario, with the diffuse X-ray emission well below the Suzaku upper limits, the lobes in the system are instead dominated by the magnetic pressure. In this case, the observed γ-ray flux is not likely to be produced within the lobes, but instead within the nuclear parts of the jet. By means of synchrotron self-Compton modeling, we show that this possibility could be consistent with the broad-band data collected for the unresolved core of Centaurus B, including the newly derived Suzaku spectrum.

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Active galaxy 4U 1344-60: did the relativistic line disappear?

Cited by 3 publications

References 59 publications

An X-ray variable absorber within the broad line region in Fairall 51

An X-ray variable absorber within the broad line region in Fairall 51

Ripple effects and oscillations in the broad Fe Kα line as a probe of massive black hole mergers

Fermi-LAT andSuzakuobservations of the radio galaxy Centaurus B

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