Related papers: Echo Tomography of Sco X-1 using Bowen Fluorescenc…
We studied the outburst properties of the hyper-luminous X-ray source ESO 243-49 HLX-1, using the full set of Swift monitoring observations. We quantified the increase in the waiting time, recurrence time, and e-folding rise timescale along…
Sco X-1, the brightest low mass X-ray binary, is likely to be a source for gravitational wave emission. In one mechanism, emission of a gravitational wave arrests the increase in spin frequency due to the accretion torque in a low mass…
The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most luminous source of continuous gravitational-wave radiation for interferometers such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be sustained by…
Neutron stars in low-mass X-ray binaries are considered promising candidate sources of continuous gravitational-waves. These neutron stars are typically rotating many hundreds of times a second. The process of accretion can potentially…
We present a systematic, homogeneous analysis of all the EXOSAT ME, high time resolution data on Sco X-1. We investigate all power spectral properties of the $<$100 Hz quasi-periodic oscillations (QPO) and noise of Sco X-1 as a function of…
Scorpius X-1 (Sco X-1) and X-ray transient (XTE) J1751-305 are Low-Mass X-ray Binaries (LMXBs) that may emit continuous gravitational waves detectable in the band of ground-based interferometric observatories. Neutron stars in LMXBs could…
We consider the cross-correlation search for periodic GWs and its potential application to the LMXB Sco X-1. This method coherently combines data from different detectors at the same time, as well as different times from the same or…
We present an optical and infrared (IR) study of IC 10 X-2, a high-mass X-ray binary in the galaxy IC 10. Previous optical and X-ray studies suggest X-2 is a Supergiant Fast X-ray Transient: a large-amplitude (factor of $\sim$ 100),…
The radio components associated with the LMXB Sco X-1 have been monitored with extensive VLBI imaging at 1.7 and 5.0 GHz over four years, including a 56-hour continuous VLBI observation in 1999 June. We often detected one strong and one…
Scorpius X-1 is the brightest and first discovered X-ray source in the sky. Studying this source in the low-energy band has been challenging in the past due to its high brightness. However, with the X-ray SPECtroscopy and Timing (XSPECT)…
We obtained relatively high signal-to-noise X-ray spectral data of the early massive star tau Sco (B0.2V) with the Suzaku XIS instrument. This source displays several unusual features that motivated our study: (a) redshifted absorption in…
Details of simultaneous photometric and spectroscopic observations of the optical counterpart of the `supersoft' X-ray source 1E 0035.4-7230 (SMC 13) are presented. Although the spectrum is dominated by emission lines of He II, the Balmer…
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 present results of a detailed study of X-ray flaring in the Z-track source Sco X-1 in a highly super-Eddington state made using high quality Rossi-XTE data from the PCA and HEXTE instruments. The emission model successfully used to…
We present WHT and VLT spectroscopy of MM Ser, the optical counterpart to Ser X-1. We deblend the red spectra of the two close stars identified by Wachter (1997) and show that the brighter of the two is responsible for the Halpha and HeI…
The evolution of the radio emission from Sco X-1 is determined from a 56-hour continuous VLBI observation and from shorter observations over a four-year period. The radio source consists of a variable core near the binary, and two variable…
Rapidly-rotating neutron stars are the only candidates for persistent high-frequency gravitational wave emission, for which a targeted search can be performed based on the spin period measured from electromagnetic (e.g. radio and X-ray)…
Low-mass X-ray binaries have long been theorised as potential sources of continuous gravitational-wave radiation, yet there is no observational evidence from recent LIGO/Virgo observing runs. Even for the theoretically 'loudest' source, Sco…
Bright, short duration X-ray flares from accreting compact objects produce thin, dust scattering rings that enable dust echo tomography: high precision distance measurements and mapping of the line-of-sight distribution of dust. This work…
Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional Luminous Blue Variable (LBV) phase…