Search Publications
1ES 1927+654: a bare Seyfert 2
Fabian, A. C.; Cackett, E. M.; Panessa, F. +3 more
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 observations obtained in 2011 are used to study the X-ray properties of 1ES 1927+654. The spectral energy distribution derived from simultaneous optical-to…
X-ray emission from the ultramassive black hole candidate NGC 1277: implications and speculations on its origin.
Fabian, A. C.; Miller, J. M.; Sanders, J. S. +2 more
We study the X-ray emission from NGC 1277, a galaxy in the core of the Perseus cluster, for which van den Bosch et al. have recently claimed the presence of an ultramassive black hole (UMBH) of mass 1.7× 10^{10}{ M_{{⊙}}}, unless the initial mass function of the stars in the stellar bulge is extremely bottom heavy. The X-rays originate in a power-…
An X-ray-UV correlation in Cen X-4 during quiescence
Degenaar, N.; Wijnands, R.; Miller, J. M. +3 more
Quiescent emission from the neutron star low-mass X-ray binary Cen X-4 is seen to be variable on time-scales from hundreds of seconds to years, suggesting that at least in this object, low-level accretion is important during quiescence. Here, we present results from recent XMM-Newton and Swift observations of Cen X-4, where the X-ray flux (0.5-10 …
Discovery of 47-s pulsations in the X-ray source 1RXS J225352.8+624354
Götz, D.; Moretti, A.; Sidoli, L. +5 more
We report on the discovery of pulsations at a period of ∼47 s in the persistent X-ray source 1RXS J225352.8+624354 (1RXS J2253) using five Chandra observations performed in 2009. The signal was also detected in Swift and ROSAT data, allowing us to infer over a 16-yr baseline an average, long-term period increasing rate of ≈17 ms per year and there…
2006 May-July major radio flare episodes in Cygnus X-3: spectrotiming analysis of the X-ray data
Droulans, R.; Koljonen, K. I. I.; Hannikainen, D. C. +1 more
We analyse in detail the X-ray data of the microquasar Cygnus X-3 obtained during major radio flaring episodes in 2006 with multiple observatories. The analysis consists of two parts: probing the fast (∼1 min) X-ray spectral evolution with principal component analysis followed by subsequent spectral fits to the time-averaged spectra (∼3 ks). Based…
A census of quasar-intrinsic absorption in the Hubble Space Telescope archive: systems from high-resolution echelle spectra
Charlton, Jane C.; Masiero, Joseph R.; Tripp, Todd M. +9 more
We present a census of zabs ≲ 2 intrinsic (those showing partial coverage) and associated (zabs ∼ zem) quasar absorption-line systems detected in the Hubble Space Telescope archive of Space Telescope Imaging Spectrograph echelle spectra. This work complements the Misawa et al. survey of 2 < zem < 4…
Ultraviolet and X-ray variability of NGC 4051 over 45 days with XMM-Newton and Swift
Vaughan, S.; Uttley, P.; Alston, W. N.
We analyse 15 XMM-Newton observations of the Seyfert galaxy NGC 4051 obtained over 45 d to determine the ultraviolet (UV) light curve variability characteristics and search for correlated UV/X-ray emission. The UV light curve shows variability on all time-scales, however with lower fractional rms than the 0.2-10 keV X-rays. On days-weeks time-scal…
A high molecular fraction in a subdamped absorber at z = 0.56
Prochaska, J. Xavier; Tejos, Nicolas; Bechtold, Jill +8 more
Measuring rest-frame ultraviolet rotational transitions from the Lyman and Werner bands in absorption against a bright background continuum is one of the few ways to directly measure molecular hydrogen (H2). Here, we report the detection of absorption from H2 at z = 0.56 in a subdamped Lyα system with neutral hydrogen column …
A multiwavelength study of the Magellanic-type galaxy NGC 4449 - I. Modelling the spectral energy distribution, the ionization structure and the star formation history
Cooray, A.; Page, M. J.; Lebouteiller, V. +16 more
We present an integrated photometric spectral energy distribution (SED) of the Magellanic-type galaxy NGC 4449 from the far-ultraviolet (UV) to the submillimetre, including new observations acquired by the Herschel Space Observatory. We include integrated UV photometry from the Swift Ultraviolet and Optical Telescope using a measurement technique …
SHARDS: stellar populations and star formation histories of a mass-selected sample of 0.65 < z < 1.1 galaxies
Barro, Guillermo; Pérez-González, Pablo G.; Tresse, Laurence +10 more
We report on results from the analysis of a stellar mass-selected (log (M*/M⊙) ≥ 9.0) sample of 1644 galaxies at 0.65 < z < 1.1 with ultradeep (mAB < 26.5) optical medium-band (R ∼ 50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows u…