Browsing Articles by Author "Fabian, A. C."

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1ES 1927+654: a bare Seyfert 2

Gallo, Luigi C.; MacMackin, C.; Vasudevan, R.; Cackett, E. M.; Fabian, A. C.; Panessa, F. (Oxford University Press, 2013-07)

1ES 1927+654 is an active galactic nucleus (AGN) that appears to defy the unification model. It exhibits a type-2 optical spectrum, but possesses little X-ray obscuration. XMM–Newton and Suzaku ...
1H 0707−495 in 2011: an X-ray source within a gravitational radius of the event horizon

Gallo, Luigi C.; Fabian, A. C.; Zoghbi, A.; Wilkins, D. R.; Dwelly, T.; Uttley, P.; Schartel, N.; Miniutti, G.; Grupe, D.; Komossa, S. (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 ...
A blurred reflection interpretation for the intermediate flux state in Mrk 335

Gallo, Luigi C.; Bonson, K.; Fabian, A. C.; Grupe, D.; Komossa, S.; Longinotti, A. L.; Miniutti, G.; Walton, D. J.; Zoghbi, A.; Mathur, S. (Oxford University Press, 2013-01)

As part of a long-term monitoring campaign of Mrk 335, deep XMM–Newton observations catch the narrow-line Seyfert 1 galaxy (NLS1) in a complex, intermediate flux interval as the active galaxy is transiting from low to high ...
Caught in the act: measuring the changes in the corona that cause the extreme variability of 1H 0707−495

Wilkins, D. R.; Kara, E.; Fabian, A. C.; Gallo, Luigi C. (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 ...
Flaring from the supermassive black hole in Mrk 335 studied with Swift and NuSTAR

Wilkins, D. R.; Gallo, Luigi C.; Grupe, D.; Bonson, K.; Komossa, S.; Fabian, A. C. (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 ...
How the effects of resonant absorption on black hole reflection spectra can mimic high-velocity outflows

Gallo, Luigi C.; Fabian, A. C. (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 ...
Insights on the X-ray weak quasar phenomenon from XMM–Newton monitoring of PHL1092

Gallo, Luigi C.; Miniutti, G.; Brandt, W. N.; Schneider, D. P.; Fabian, A. C.; Boller, Th. (Royal Astronomical SocietyOxford University Press, 2012)

PHL 1092 is a z ∼ 0.4 high-luminosity counterpart of the class of Narrow-Line Seyfert 1 galaxies. In 2008, PHL 1092 was found to be in a remarkably low X-ray flux state during an XMM–Newton observation. Its 2 keV flux ...
Long XMM observation of the narrow-line Seyfert 1 galaxy IRAS 13224−3809: rapid variability, high spin and a soft lag

Gallo, Luigi C.; Fabian, A. C.; Kara, E.; Walton, D. J.; Wilkins, D. R.; Ross, R. R.; Lozanov, K.; Uttley, P.; Zoghbi, A.; Miniutti, G. (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 ...
Modelling the broad Fe K alpha reverberation in the AGN NGC 4151

Cackett, E. M.; Zoghbi, A.; Reynolds, C.; Fabian, A. C.; Kara, E.; Uttley, P.; Wilkins, D. R. (Oxford University Press, 2014-01-13)

The recent detection of X-ray reverberation lags, especially in the Fe Kα line region, around active galactic nuclei (AGN) has opened up the possibility of studying the time-resolved response (reflection) of hard ...
Modelling the extreme X-ray spectrum of IRAS 13224-3809

Chiang, Chia-Ying; Walton, D. J.; Fabian, A. C.; Wilkins, D. R.; Gallo, Luigi C. (Oxford University Press, 2015-01)

The extreme narrow-line Seyfert 1 galaxy IRAS 13224-3809 shows significant variability, frequency depended time lags, and strong Fe K line and Fe L features in the long 2011 XMM-Newton observation. In this work we study ...
Multi-epoch X-ray observations of the Seyfert 1.2 galaxy Mrk 79: bulk motion of the illuminating X-ray source

Gallo, Luigi C.; Miniutti, G.; Miller, J. M.; Brenneman, L. W.; Fabian, A. C.; Guainazzi, M.; Reynolds, C. S. (Oxford University Press, 2011-02)

Multi-epoch X-ray spectroscopy (0.3–25 keV) of the Seyfert 1.2 galaxy Mrk 79 (UGC3973) spanning nearly 8 yr and a factor of 3 in broad-band flux are analysed. The data are obtained at seven epochs with either XMM–Newton ...
New constraints on the black hole low/hard state inner accretion flow with NuSTAR

Miller, J. M.; Tomsick, J. A.; Bachetti, M.; Wilkins, D. R.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; Grefenstette, B. W.; Hailey, C. J. (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, ...
The NuSTAR spectrum of Mrk 335: extreme relativistic effects within two gravitational radii of the event horizon

Parker, M. L.; Wilkins, D. R.; Fabian, A. C.; Grupe, D.; Dauser, T.; Matt, G.; Harrison, F. A.; Brenneman, L.; Boggs, S. E.; Christensen, F. E.; Gallo, Luigi C. (Oxford University Press, 2014-09-11)

We present 3–50 keV NuSTAR observations of the active galactic nuclei Mrk 335 in a very low flux state. The spectrum is dominated by very strong features at the energies of the iron line at 5–7 keV and Compton ...
The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

Gallo, Luigi C.; Fabian, A. C. (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 ...
PHL 1092 as a transient extreme X-ray weak quasar

Gallo, Luigi C.; Miniutti, G.; Fabian, A. C.; Brandt, W. N.; Boller, Th. (Royal Astronomical SocietyOxford University Press, 2009)

We report a dramatic variability event in the X-ray history of the narrow-line quasar PHL 1092 (z = 0.396). Our latest 2008 XMM-Newton observation reveals a flux drop of ∼200 with respect to the previous observation performed ...
The quasar PG 0844+349 in an X-ray weak state

Gallo, Luigi C.; Grupe, D.; Schartel, N.; Komossa, S.; Miniutti, G.; Fabian, A. C.; Santos-Lleo, M. (Oxford University Press, 2011-03)

In 2009 March the well-studied quasar, PG 0844+349, was discovered with Swift to be in an X-ray weak state. A follow-up XMM–Newton observation several weeks later generated a good-quality spectrum of the source, showing ...
Searching for correlations in simultaneous X-ray and UV emission in the narrow-line Seyfert 1 galaxy 1H 0707–495

Robertson, D. R. S.; Gallo, Luigi C.; Zoghbi, A.; Fabian, A. C. (Oxford University Press, 2015-09-09)

We examine simultaneous X-ray and UV light curves from multi-epoch 8 d XMM–Newton observations of the narrow line Seyfert 1 galaxy 1H 0707–495. The simultaneous observations reveal that both X-ray and UV emission are ...
A selection effect boosting the contribution from rapidly spinning black holes to the cosmic X-ray background

Vasudevan, R. V.; Fabian, A. C.; Reynolds, C. S.; Aird, J.; Dauser, T.; Gallo, Luigi C. (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 ...
Stellar-mass black hole spin constraints from disk reflection and continuum modeling

Gallo, Luigi C.; Miller, J. M.; Reynolds, C. S.; Fabian, A. C.; Miniutti, G. (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 ...
Suzaku observations of Mrk 335: confronting partial covering and relativistic reflection

Gallo, Luigi C.; Wilkins, D. R.; Bonson, K.; Chiang, C.-Y.; Grupe, D.; Parker, M. L.; Zoghbi, A.; Fabian, A. C.; Komossa, S.; Longinotti, A. L. (Oxford University Press, 2015-01)

We report on the deepest X-ray observation of the narrow-line Seyfert 1 galaxy Mrk 335 in the low-flux state obtained with Suzaku. The data are compared to a 2006 high-flux Suzaku observation when the source was ∼10 times ...