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Browsing Articles by Subject "Black holes (Astronomy)"
Now showing items 1-19 of 19
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(Oxford University Press, 2012)The narrow-line Seyfert 1 Galaxy 1H 0707−495 went into a low state from 2010 December to 2011 February, discovered by a monitoring campaign using the X-Ray Telescope on the Swift satellite. We triggered a 100 ks XMM–Newton ...
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(Oxford University Press, 2013-05)A recent approach to simulating localized feedback from active galactic nuclei (AGN) by Power et al. uses an accretion disc particle to represent both the black hole and its accretion disc. We have extrapolated and adapted ...
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(Springer, 2014-05-21)We study the properties of the quantum information transmission channel that emerges from the quantum dynamics of particles interacting with a black hole horizon. We calculate the quantum channel capacity in two limiting ...
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(Oxford University Press, 2014-09-21)The X-ray spectra of the narrow-line Seyfert 1 galaxy, 1H 0707–495, obtained with XMM–Newton, from time periods of varying X-ray luminosity are analysed in the context of understanding the changes to the X-ray ...
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(Oxford University Press, 2013-05)Modelling active galactic nuclei (AGN) feedback in numerical simulations is both technically and theoretically challenging, with numerous approaches having been published in the literature. We present a study of five ...
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(American Astronomical Society, 2015-02-20)SDSS J015957.64+003310.5 is an X-ray selected, z = 0.31 active galactic nucleus (AGN) from the Stripe 82X survey that transitioned from a Type 1 quasar to a Type 1.9 AGN between 2000 and 2010. This is the most distant AGN, ...
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(Oxford University Press, 2015-12-21)Monitoring of the narrowline Seyfert 1 galaxy Markarian 335 (Mrk 335) with the Swift satellite discovered an X-ray flare beginning 2014 August 29. At the peak, the 0.5–5 keV count rate had increased from that in the low-flux ...
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High Density Reflection Spectroscopy – II. the density of the inner black hole accretion disc in AGN (Oxford University PressRoyal Astronomical Society, 2019-08-22)We present a high density disc reflection spectral analysis of a sample of 17 Seyfert 1 galaxies to study the inner disc densities at different black hole mass scales and accretion rates. All the available XMM– ...
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(Oxford University Press on behalf of the Royal Astronomical Society, 2011-11)Narrow absorption lines seen in the 2–10 keV spectra of active galaxies and Galactic black holes are normally attributed to iron in high-velocity outflows or inflows. We consider the possibility that such features could ...
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(Oxford University Press, 2016-05-11)Being one of only two fundamental properties black holes possess, the spin of supermassive black holes (SMBHs) is of great interest for understanding accretion processes and galaxy evolution. However, in these early days ...
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(Oxford University Press, 2013-03-11)The narrow-line Seyfert 1 galaxy IRAS 13224−3809 has been observed with XMM–Newton for 500 ks. The source is rapidly variable on time-scales down to a few 100 s. The spectrum shows strong broad Fe − K and L emission ...
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(American Astronomical Society, 2015-01-20)We report on an observation of the Galactic black hole candidate GRS 1739−278 during its 2014 outburst, obtained with NuSTAR. The source was captured at the peak of a rising “low/hard” state, at a flux of ~0.3 Crab. A broad, ...
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The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc (Oxford University Press, 2013-09)In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) – highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly ...
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(Oxford University Press, 2017-12)To gain a better understanding of the inner disc region that comprises active galactic nuclei, it is necessary to understand the pattern in which the disc is illuminated (the emissivity profile) by X-rays emitted from the ...
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(Oxford University Press, 2017-11)X-ray spectral timing analysis is presented of XMM–Newton observations of the narrow-line Seyfert 1 galaxy I Zwicky 1 taken in 2015 January. After exploring the effect of background flaring on timing analyses, X-ray ...
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(Oxford University Press, 2016-05-11)The cosmic X-ray background (CXB) is the total emission from past accretion activity on to supermassive black holes in active galactic nuclei (AGN) and peaks in the hard X-ray band (30 keV). In this paper, we identify a ...
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(American Astronomical SocietyIOP Publishing, 2009-05-20)Accretion disk reflection spectra, including broad iron emission lines, bear the imprints of the strong Doppler shifts and gravitational redshifts close to black holes. The extremity of these shifts depends on the proximity ...
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(Oxford University Press, 2013-02)We present an X-ray spectral analysis of a large sample of 25 ‘bare’ active galactic nuclei (AGN), sources with little or no complicating intrinsic absorption, observed with Suzaku. Our work focuses on studying the potential ...
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(Oxford University Press, 2015-03)We study the X-ray properties of a sample of 14 optically selected low-mass active galactic nuclei (AGN) whose masses lie within the range 10[superscript 5]–2 × 10[superscript 6] M[subscript circled dot] with XMM–Newton. ...
Now showing items 1-19 of 19