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Browsing by Author "Gallo, Luigi C."
Now showing items 21-40 of 62
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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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(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 ...
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(Halifax, N.S. : Saint Mary's University, 2019)X-ray observations of two Seyfert AGN were analysed in an effort to characterise the nature of their variability. A spectral analysis was performed on a Suzaku observation of the Seyfert 1.5 AGN Mrk 530, and a timing ...
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(Oxford University Press, 2015-06-11)A multi-epoch, multi-instrument analysis of the Seyfert 1 galaxy HE 0436–4717 is conducted using optical to X-ray data from XMM–Newton and Swift (including the Burst Alert Telescope). Fitting of the UV-to-X-ray spectral ...
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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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(Oxford University PressRoyal Astronomical Society, 2019-01-16)We present results from a deep, coordinated XMM–Newton + NuSTAR observation of the Seyfert 2 galaxy IRAS 00521−7054. The NuSTAR data provide the first detection of this source in ...
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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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(Halifax, N.S. : Saint Mary's University, 2020)The multi-epoch data involving 27 observations of the blazar 3C273 obtained over a period of 16 years from June 2000 to June 2016 in the 0.3-10 keV x-ray band is analysed. A single power-law model is fitted to the hard ...
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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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(Halifax, N.S. : Saint Mary's University, 2013)Ultraluminous Infrared Galaxies (ULIRGs) are one of the brightest sources of infrared radiation in the Universe, with luminosities upwards of 10 [superscript 12] times that of the Sun. To produce the extreme infrared ...
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(Halifax, N.S. : Saint Mary’s University, 2018)Principal Component Analysis (PCA) is applied to a variety of blazars to examine X-ray spectral variability. Data from nine different objects are analysed in two ways: long-term, which examines variability trends across ...
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(Halifax, N.S. : Saint Mary's University, 2021)High-velocity outflows in active galactic nuclei usually manifest as either a collimated jet or diffuse wind. These outflows carry a significant amount of energy from the central environment surrounding the supermassive ...
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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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(Halifax, N.S. : Saint Mary's University, 2021)Five jetted sources are used in this work to probe the relationship between the X-ray and Radio emission from radio-loud active galactic nuclei. Timing techniques probing variability, light curve correlation, and power ...
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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 ...
Now showing items 21-40 of 62