Search Publications
Decade‑long X‑ray observations of HESS J0632+057
Santangelo, Andrea; Pühlhofer, Gerd; Chernyakova, Maria +1 more
We present the results of a decade of X‑ray observations of the gamma ray loud binary HESS J0632+057 and interpret the available broadband data in view of the system geometry and emission mechanisms. We have performed an analysis of all X‑ray data available to date from Swift, XMM‑Newton, Chandra, NuSTAR, and Suzaku. We refine the orbital period o…
Observations of X‑ray reverberation around black holes
Ponti, G.; De Marco, B.
The X‑ray emission from accreting black hole (BH) systems displays strong variability. Short reverberation lags are expected between the primary hard X‑ray continuum and the reprocessed disk emission. These lags depend on light‑travel distances, thus offering the opportunity to map the geometry of the innermost accretion flow. X‑ray reverberation …
The nonlinear X‑ray/ultraviolet relation in active galactic nuclei: Contribution of instrumental effects on the X‑ray variability
Lusso, E.
We have recently demonstrated that the nonlinear relation between ultraviolet and X‑ray luminosity in quasars is very tight (with an intrinsic dispersion of ∼0.2 dex), once contaminants (e.g., dust reddening, X‑ray absorption), variability, and differences in the active galactic nuclei physical properties are taken into account. This relation has …
The complex phenomena of young stellar objects revealed by their X‑ray variability
Reale, F.; Sciortino, S.; Pillitteri, I. +1 more
X‑ray observations of young stellar objects (YSOs) have shown several complex phenomena at work. In recent years, a few X‑ray programs based on long, continuous, and, sporadically, simultaneous coordinated multiwavelength observations have paved the way to our current understanding of the physical processes at work, which very likely regulates the…
Tidal disruption events: Past, present, and future
Motch, C.; Komossa, S.; Lira, P. +6 more
The tidal disruption of a star by a nuclear supermassive black hole was predicted in the 1970s and first confirmed by soft X‑ray flares seen from quiescent galaxies in the ROSAT all‑sky survey. We report here on the discovery of a new candidate tidal disruption event, 1RXS J075908.8 + 074835, from the ROSAT bright source catalog, which faded by a …
Unification of strongly magnetized neutron stars with regard to X‑ray emission from hot spots
Hayashida, K.; Nakajima, H.; Matsumoto, H. +1 more
Strongly magnetized isolated neutron stars (NSs) are categorized into two families according, mainly, to their magnetic field strength. The one with a higher magnetic field of 1014–1015 Gauss is called "magnetar," and the other is the X‑ray isolated neutron star (XINS) with 1013 Gauss. Both magnetars and XINSs show thermal emission in X‑rays, whos…
Constraints on the number of X‑ray pulsars in IC 10 from a deep XMM‑Newton observation
Wik, D. R.; Yang, J.; Laycock, S. G. T.
We report the most sensitive search yet for X‑ray pulsars in the dwarf starburst galaxy IC 10, which is known to contain a population of young, high‑mass X‑ray binaries. We searched for pulsations in 207 point‑like X‑ray sources in the direction of IC 10 by a 2012 XMM‑Newton observation with a total exposure time of 134.5 ks. Pulsation searches in…
Simultaneous Kepler/K2 and XMM‑Newton observations of superflares in the Pleiades
Antoniou, V.; Micela, G.; Stauffer, J. +9 more
Together with coronal mass ejection, flares are the most energetic stellar magnetic events, ignited by a sudden release of magnetic energy, which triggers a cascade of interconnected phenomena, each resulting in emission in different bands. For this reason, flares are intrinsic multiwavelength phenomena. In particular, optical and soft X‑ray emiss…
Automatic detection of tidal disruption events and other long‑duration transients in XMM‑Newton data
Webb, N. A.
XMM‑Newton's large field of view and excellent sensitivity have resulted in hundreds of thousands of serendipitous X‑ray detections. While their spectra have been widely exploited, their variable nature has been little studied. Part of this is due to the way XMM‑Newton currently operates, where observations generally have a 12‑month proprietary pe…
Energy‑dependent timing studies of the low‑hard state of black hole X‑ray binaries with XMM‑Newton
Kong, Albert K. H.; Stiele, Holger
Almost all low‑mass black hole X‑ray binaries are transient sources. Most of these sources show a hysteresis: they evolve from the low‑hard state through intermediate state(s) into the high‑soft state and then return to the hard state at lower luminosity, again passing through the intermediate states. However, there are outbursts that remain in th…