Related papers: A long-term optical - X-ray correlation in 4U 1957…
[abridged] The LMXB 4U 0614+091 is a source of sporadic thermonuclear (type I) X-ray bursts. We find bursts with a wide variety of characteristics in serendipitous wide-field X-ray observations by EURECA/WATCH, RXTE/ASM, BeppoSAX/WFC,…
We present results of the first multicolour photometric study of 4U1957+115, one of the optically less studied low mass X-ray binaries (LMXB). Our quasi-simultaneous UBVRI observations reveal that the light curve pulse shape over the 9.33…
We report a detailed spectro-temporal analysis of the black hole (BH) low mass X-ray binary (LMXB) 4U 1543-475 during its 2021 outburst using the data from LAXPC (Large Area X-ray Proportional Counters) and SXT (Soft X-ray Telescope)…
XSSJ1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGLJ1227.9-4852/2FGLJ1227.7-4853. Multi-wavelength observations have added information on this source, indicating a low-luminosity…
We report the discovery of the orbital period of the ultracompact low-mass X-ray binary (LMXB) 4U 1543-624 using time-resolved optical photometry taken with the 6.5-m Clay (Magellan II) telescope in Chile. The light curve in the Sloan r'…
We have obtained high time resolution (seconds) photometry of LMC X-2 in December 1997, simultaneously with the Rossi X-ray Timing Explorer (RXTE), in order to search for correlated X-ray and optical variability on timescales from seconds…
We report the first detection of a linear correlation between rms variability amplitude and flux in the Ultraluminous X-ray source NGC 5408 X-1. The rms-flux relation has previously been observed in several Galactic black hole X-ray…
We report the first statistically significant detection of X-ray polarization from the high-mass X-ray binary (HMXB) 4U 1700-377, observed using the Imaging X-ray Polarimetry Explorer (IXPE). A polarization degree exceeding 10% was detected…
The most luminous X-ray sources in nearby elliptical galaxies are likely black hole low-mass X-ray binaries (BHLMXBs). In the Milky Way, such systems are always transient, and with the exception of GRS1915+105 have burst durations on the…
The black-hole binary LMC X-3 is known to be variable on time scales of days to years. We investigate X-ray and ultraviolet variability in the system as a function of the 1.7 day binary phase using a 6.4 day observation with the Rossi X-ray…
Using simultaneous observations in X-rays and optical, we have performed a homogeneous analysis of the cross-correlation behaviours of four X-ray binaries: SWIFT J1753.5-0127, GX 339-4, Sco X-1, and Cyg X-2. With high time-resolution…
In this study, we examine 51 archival NICER observations and 6 archival NuSTAR observations of the neutron star (NS) ultra-compact X-ray binary (UCXB) 4U 0614+091, which span over 5 years. The source displays persistent reflection features,…
This paper presents the results of a dense and intensive X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051 carried out in 2000. Results of the optical analysis are consistent with previous measurements. The amplitude…
We present long term monitoring of MCG-6-30-15 in X-rays, optical and near-IR wavelengths, collected over five years of monitoring. We determine the power spectrum density of all the observed bands and show that after taking into account…
We present a new spectro-polarimetric method for estimation of the inclination of X-ray binaries using the linear polarization (LP) value in black hole (BH) sources, based on the early paper by Sunyaev \& Titarchuk (1985, ST85). The X-ray…
We report a detailed spectral analysis of the population of low-mass X-ray binaries (LMXBs) detected in the elliptical galaxy NGC~4278 with Chandra. Seven luminous sources were studied individually, four in globular clusters (GCs), and…
The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pulsations have not been detected in the time range 0.001-1000 s. A cyclotron line at ~30 keV has been suggested by various…
4U 1543-624 is a relatively bright persistent low-mass X-ray binary. Analysis of archival data from ASCA, SAX and RXTE is presented. The X-ray continuum be can modeled with the standard low-mass X-ray binary spectrum, an isothermal…
We present cross-correlation studies of gamma-ray (0.1-300 GeV), X-ray (0.2-10 keV) and optical (R-band) variability of a sample of 26 blazars during 2008-2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar…
Ultra-compact X-ray binaries (UCXBs) are a subclass of low-mass X-ray binaries (LMXBs) characterised by tight orbits and hydrogen-poor donor stars. We present a spectral and timing study in the hard X-ray band of 11 of the 20 confirmed…