Search Publications
Accretion in Strong Gravity: from Galactic to Supermassive Black Holes
Done, Chris; Gierliński, Marek
The galactic black hole binary systems give an observational template showing how the accretion flow changes as a function of increasing mass accretion rate, or L/LEdd. These data can be synthesised with theoretical models of the accretion flow to give a coherent picture of accretion in strong gravity, in which the major hard-soft spect…
On the Nature of the Unidentified X-ray/γ-ray Sources Igr J18027–1455 and Igr J21247+5058
Mirabel, I. F.; Combi, J. A.; Ribó, M.
We present a multiwavelength study of the environment of the unidentified X-ray/γ-ray sources IGR J18027–1455 and IGR J21247 + 5058, recently discovered by the IBIS/ISGRI instrument, onboard the INTEGRAL satellite. The main properties of the sources found inside their position error circles, give us clues about the nature of these high-energy sour…
Rapid X-Ray Variability of Seyfert 1 Galaxies
Iwasawa, K.; Vaughan, S.; Fabian, A. C.
The rapid and seemingly random fluctuations in X-ray luminosity of Seyfert galaxies provided early support for the standard model in which Seyferts are powered by a supermassive black hole fed from an accretion disc. However, since EXOSAT there has been little opportunity to advance our understanding of the most rapid X-ray variability. Observatio…
The Seyfert-Liner Galaxy NGC 7213: An XMM-Newton Observation
Page, M. J.; Branduardi-Raymont, G.; Soria, R. +3 more
We examine the XMM X-ray spectrum of the low-ionisation nuclear emission-line region (LINER)-AGN NGC 7213, which is best fit with a power law, Kα emission lines from Fe I, Fe XXV and Fe XXVI and a soft X-ray collisionally ionised thermal plasma with kT = 0.18+0.03‑0.01 keV. We find a luminosity of 7× 10‑4 LEdd…
Astrometric Solution of the Multiple System Xy Leo
Erdem, Ahmet; Bakis, Volkan; Budding, Edwin +2 more
An astrometric solution, together with time of minimum analysis, has been made for the multiple system XY Leonis (HIP 49136) to identify the properties of the remote companion to the eclipsing pair (AB). From this solution, we derive the inclination of the wide orbit (AB-cd) as 94.4∘± 0.2∘, angle of nodes as 247.3∘…
Optical and X-Ray Observations of the Symbiotic System Ag Draconis During Quiescence and Outburst
Friedjung, Michael; González-Riestra, Rosario; Greiner, Jochen +6 more
We review the main characteristics of the symbiotic system AG Draconis, with special emphasis on its optical and X-ray variations. We also discuss the X-ray to visual energy distribution during quiescence and outburst and describe our spectroscopic and X-ray observations during the 2003 outburst.
Proper motion study of the ROSAT selected WTTS candidates around Taurus-Auriga
LI, J. Z.
Astrometric study of the T Tauri stars (TTS) candidates and non-TTS X-ray sources around Tau-Aur [Li, Hu 132 (1998) 173], based on the Hipparcos and the ACT Reference Catalogue, is presented in this paper. The ROSAT selected X-ray sources are found to have complicated nature. A few of them are associated with the Tau-Aur or the Orion Star Forming …
AGNS and MICROQUASARS As High-Energy γ-Ray Sources
Paredes, Josep M.
The extragalactic analogs of the microquasars, the quasars, are strong γ-ray emitters at GeV energies. It is expected that microquasars are also γ-ray sources, because of the analogy with quasars and because theoretical models predict the high-energy emission. There are two microquasars that appear as the possible counterparts for two unidentified…
Periodicity Search in the X-ray Data of RX J0007.0+7302
Lin, Lupin C. -C.; Chang, Hsiang-Kuang
Some unidentified EGRET sources have been reported to have probable X-ray counterparts. Periodicities in the X-ray data of those sources, if found, may help to strengthen the identification and to reveal their nature. We performed a detailed search of periodicities with a photon-counting method, the H-test, in the XMM and ASCA data of RX J0007.0+7…
Preliminary Analysis of <Emphasis Type="BoldItalic">V</Emphasis> and <Emphasis Type="BoldItalic">Hp</Emphasis> Light Curves of 26 Carbon Miras
MikulÁšek, Zdeněk; GrÁf, TomÁš
Light variations of a representative sample of 26 more or less periodically variable carbon stars were analyzed on the basis of 2220 individual observations made by the Hipparcos satellite and 33 544 visual observations listed in AFOEV and VSOLJ databases within the interval JD = 2 448 000 (1988) ±6 cycles. We found the osculating linear ephemerid…