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Browsing Articles by Author "Gallo, Luigi C."
Now showing items 21-40 of 45
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(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 ...
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(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 ...
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(Royal Astronomical SocietyOxford University Press, 2019-09-12)We present XMM–Newton, NuSTAR, Swift, and Hubble Space Telescope observations of the Narrow-line Seyfert 1 galaxy Mrk 335 in a protracted low state in 2018 and 2019. The X-ray flux ...
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(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 ...
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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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(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 ...
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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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(EDP Sciences, 2015-03)We have conducted a multiwavelength survey of 42 radio loud narrow-line Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse ...
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(EDP Sciences, 2017-07)This article is an erratum for: Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies (Astronomy & Astrophysics vol 575, A13, 2015).
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(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 ...
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Radio-to-[gamma]-ray monitoring of the narrow-line Seyfert 1 galaxy PMN J0948+0022 from 2008 to 2011 (EDP Sciences, 2012-11)We present more than three years of observations at different frequencies, from radio to high-energy [gamma]-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z = 0.585). This source is the first NLS1 detected ...
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(American Astronomical Society, 2012-04)The narrow-line Seyfert 1 galaxy (NLS1) Mkn 335 is remarkable because it has repeatedly shown deep, long X-ray low states that show pronounced spectral structure. It has become one of the prototype active galactic nuclei ...
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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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(American Astronomical SocietyIOP Publishing, 2013-04-01)We present the discovery of an outflowing ionized wind in the Seyfert 1 galaxy Mrk 335. Despite having been extensively observed by most of the largest X-ray observatories in the last decade, this bright source was not ...
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(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 ...
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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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(Springer Nature, 2017-11--2)The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae1. Therefore, X-ray spectroscopy of the intracluster medium ...
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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, 2009-10)We present the results from a monitoring campaign of the Narrow-Line Seyfert 1 galaxy PG 1211+143. The object was monitored with ground-based facilities (UBVRI photometry; from 2007 February to July) and with Swift [X-ray ...
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(EDP Sciences, 2010-05)We present a Suzaku observation of the dwarf Seyfert galaxy NGC 4395 with an estimated black hole mass of ~105M[subscript circled dot]. Rapid and strong X-ray variability with an rms amplitude of ~60 per cent is observed ...
Now showing items 21-40 of 45