Related papers: Relation between supersoft X-ray sources and VY Sc…
To investigate the transient nature of supersoft sources (SSSs) in M 31, we compared SSS candidates of the XMM-Newton Deep Survey, ROSAT PSPC surveys and the Chandra catalogues in the same field. We found 40 SSSs in the XMM-Newton…
Soft X-ray transients are systems that are detected when they go into an outburst, wherein their X-ray luminosity increases several orders of magnitude. These outbursts are markers of the poorly understood change in the spectral state of…
We present the X-ray analysis of dwarf nova EY Cyg using the 45 ks \textit{XMM-Newton} observatory archival data obtained in quiescence. We find orbital modulations in X-rays. We simultaneously fitted EPIC pn, MOS1 and MOS2 data using a…
We present new results of our X-ray monitoring of the transient binary supersoft X-ray source RX J0513.9-6951 in the LMC and of our re-analysis of optical light curves obtained during the MACHO project. We have covered a complete X-ray…
We present a 100 yr optical lightcurve of the recently discovered supersoft X-ray source RX~J0019.8+2156 as deduced from photographic plates of Harvard and Sonneberg Observatory. Apart from the periodic orbital variations two different…
We have examined ROSAT soft X-ray observations of a complete, distance-limited sample of Seyfert and LINER galaxies. X-ray data are available for 46 out of 60 such objects which lie within a hemisphere of radius 18 Mpc. We have constructed…
[HP99] 159 is remarkable as the first supersoft X-ray source (SSS) identified with an evolved helium star donor. With a likely orbital period of 1.164 d or 2.327 d, the origin of the SSS component is controversial, with the two current…
Some accreting binary systems containing a white dwarf (such as classical novae or persistent supersoft sources) are seen to emit low-energy X-rays with temperatures of ~10^6 K and luminosities exceeding 10^35 erg/s. These X-rays are…
We have analysed archival ROSAT PSPC and Einstein HRI data for the x-ray point source in the bar of NGC 6822. The source decreased in x-ray flux by at least half an order of magnitude in the 13 years between the HRI and PSPC observations.…
V745 Sco is a recurrent nova, with the most recent eruption occurring in February 2014. V745 Sco was first observed by Swift a mere 3.7 hr after the announcement of the optical discovery, with the super-soft X-ray emission being detected…
Based on high-resolution spectroscopy performed with the NES echelle spectrograph of the 6-m telescope, we have studied the peculiarities of the spectrum and the velocity field in the atmosphere and envelope of the cool supergiant V1027…
An extremely soft X-ray excess throughout galaxy clusters has been claimed as a new feature of these sytems, with important physical implications. We have reexamined this feature in the five clusters for which it has been discussed, using…
New HST observations show that the bright X-ray source in the face-on spiral galaxy NGC 1073 is located near a ring of recent star formation with an age of 8-16 Myr. This strengthens the association of X-ray sources in spiral galaxies…
We report the identification of the ROSAT all-sky survey source 1RXS J154814.5-452845as new intermediate polar and present the results from follow-up optical and X-ray observations. The source shows pulsations with a period of 693 s both in…
We present the results of ROSAT All-Sky Survey observations of Seyfert and IR-luminous galaxies from the Extended 12 Micron Galaxy Sample and the optically-selected CfA Sample. Roughly half of the Seyferts (mostly Seyfert 1s) have been…
Very faint X-ray transients (VFXTs) are X-ray transients with peak X-ray luminosities ($L_X$) of $L_X\lesssim10^{36}$ erg/s, which are not well-understood. We carried out a survey of 16 square degrees of the Galactic Bulge with the Swift…
From 2005 to 2009, 25 observations of Cyg X-1 were performed with Suzaku, achieving a total exposure of 446 ks. In all observations, the source was found in the low/hard state, while the 1.5--12.0 keV count rate of the All-Sky Monitor…
The 30-year recurrent symbiotic nova V3890 Sgr exploded 2019 August 28 and was observed with multiple X-ray telescopes. An XMM-Newton observation during the SSS phase captured a high degree of X-ray variability including a deep dip in the…
We present results of an extensive study of the X-ray spectral properties of sources detected in the RIXOS survey, that is nearly complete down to a flux limit of 3e-14 cgs (0.5-2 keV). We show that for X-ray surveys containing sources with…
All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…