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Browsing by Author "Gallo, Luigi C."
Now showing items 41-60 of 64
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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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(Halifax, N.S. : Saint Mary's University, 2013)A search for relativistically blurred Fe-L [alpha] is performed on 353 nearby broad and narrow line Type-1 active galactic nuclei (AGN). Simple phenomenological modeling is applied to establish the presence of Fe-L[alpha] ...
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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 ...
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(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 ...
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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 PressRoyal Astronomical Society, 2019-03-20)We report the discovery of RX J2317.8–4422 in an extremely low X-ray flux state by the Neil Gehrels Swift observatory in 2014 April/May. In total, the low-energy X-ray emission dropped by a factor of 100. ...
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(Halifax, N.S. : Saint Mary's University, 2023-08-01)In this work, we examine the application of the wavelet transform to the X-ray timing analyses of active galactic nuclei (AGN) and quasi-periodic eruption sources (QPEs). We find that the power spectral density (PSD) slope ...
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(Halifax, N.S. : Saint Mary's University, 2022-05-06)Identifying X-ray variability in active galactic nuclei (AGN) has been a longstanding issue due to spectral model degeneracies. It often occurs on timescales too short to employ regular spectral analysis, but colour-colour ...
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(Halifax, N.S. : Saint Mary's University, 2021)X-ray emission from Seyfert 1 galaxies has a debated origin. The primary X-ray source is the compact corona, but the secondary X-ray emission is thought to originate from either a Comptonising layer or blurred reflection ...
Now showing items 41-60 of 64