Browsing Articles by Subject "X-ray sources, Galactic"

Now showing items 1-12 of 12

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 ...
The hard X-ray perspective on the soft X-ray excess

Vasudevan, Ranjan V.; Mushotzky, Richard F.; Reynolds, Christopher S.; Fabian, Andrew C.; Lohfink, Anne M.; Zoghbi, Abderahmen; Gallo, Luigi C.; Walton, Dominic (IOP Publishing Limited, 2014-04-10)

The X-ray spectra of many active galactic nuclei exhibit a “soft excess” below 1 keV, whose physical origin remains unclear. Diverse models have been suggested to account for it, including ionized reflection ...
How well can we measure supermassive black hole spin?

Bonson, K.; Gallo, Luigi C. (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 ...
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 ...
Is HE 0436–4717 anemic? A deep look at a bare Seyfert 1 galaxy

Bonson, K.; Gallo, Luigi C.; Vasudevan, R. (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 ...
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 ...
Nonthermal X-ray emission: an alternative to cluster cooling flows?

McCarthy, Ian G.; West, Michael J.; Welch, Gary A. (American Astronomical SocietyIOP Publishing, 2002-03-10)

We report the results of experiments aimed at reducing the major problem with cooling flow models of rich cluster X-ray sources, i.e., the fact that most of the cooled gas or its products have not been found. Here we show ...
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 ...
A remarkable long-term light curve and deep, low-state spectroscopy: Swift and XMM-Newton monitoring of the NLS1 galaxy Mkn 335

Gallo, Luigi C.; Gruberbauer, Michael; Grupe, Dirk; Komossa, S.; Longinotti, Anna Lia; Fabian, Andrew C.; Pradhan, Anil K.; Xu, Dawei (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 ...
The Suzaku broadband X-ray spectrum of the dwarf Seyfert galaxy NGC 4395

Gallo, Luigi C.; Iwasawa, K.; Tanaka, Y. (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 ...