Related papers: The first extragalactic ultra-compact X-ray binary…

Aims: Study the high-mass X-ray binary X-7 in M33 using broad-band optical data. Methods: We used recently published CFHT r' and i' data for variable stars in M33 to extract the light curve of the optical counterpart of X-7. We combined…

We present new optical spectroscopy of 20 candidate counterparts of 17 X-ray sources in the direction of the M31 disc. By comparing the X-ray catalogue from the XMM-Newton survey of M31 with star catalogues from the Local Group Galaxy…

We present a detailed analysis of XMM archival data of two Ultraluminous X-ray Sources (ULXs) in the nearby spiral galaxy NGC 1313: NGC 1313 X-1 and X-2. The spectral continuum of these sources was modeled with a soft thermal component plus…

Aims. M 31 has been completely imaged for the first time obtaining a luminosity lower limit ~10^35 erg s-1 in the 0.2-4.5 keV band. Our XMM-Newton EPIC survey combines archival observations with observations taken between June 2006 and…

We have previously identified 10 M31 black hole candidates (BHCs) in M31, from their X-ray properties alone. They exhibit "hard state" emission spectra that are seen at luminosities < ~10% Eddington in X-ray binaries (XBs) containing a…

The X-ray burster 4U1850-087, located in the Galactic globular cluster NGC6712, is an ultracompact binary (orbital period~21 min),likely harbouring a degenerate companion.The source has been observed at soft gamma-rays several times with…

Gravitational waves from the binary black hole (BH) merger GW150914 may enlighten our understanding of ultra-luminous X-ray sources (ULXs), as BHs>30Msun can reach luminosities>4x10^39 erg s^-1 without exceeding their Eddington limit. It is…

Context. Ultracompact X-ray binaries (UCXBs) typically consist of a white dwarf donor and a neutron star or black hole accretor. The evolution of UCXBs and very low mass ratio binaries in general is poorly understood. Aims. We investigate…

We have obtained snapshot images of a transient X-ray source in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The Chandra position of the X-ray nova was R.A.=00:42:56.038 +/-0.08'',…

NGC 925 ULX-1 and ULX-2 are two ultraluminous X-ray sources in the galaxy NGC 925, at a distance of 8.5 Mpc. For the first time, we analyzed high quality, simultaneous XMM-Newton and NuSTAR data of both sources. Although at a first glance…

We present the results of the first broadband X-ray analysis of the ultraluminous X-ray source NGC 5055 ULX X-1, combining simultaneous data from XMM$-$Newton and NuSTAR missions, with a combined exposure time of $\sim$100 ks across the…

The ultracompact low-mass X-ray binary 4U 0513-40 in the globular cluster NGC1851 exhibits large amplitude X-ray flux variations with spectral changes from low/hard to high/soft states which have not been reported previously in other…

The high-mass X-ray binary SMC X-1 is an eclipsing binary with an orbital period of 3.89 d. This system exhibits a superorbital modulation with a period varying between ~40 d and ~65 d. The instantaneous frequency and the corresponding…

If confirmed, a wide binary system of 70 $M_{\odot}$ black hole (BH) and an 8 $M_{\odot}$ main sequence star (LB-1) is observed to reside in the Milky Way (MW). We show that long term evolution of an 8 $M_{\odot}$ star around a BH with mass…

We present the XMM-Newton observations obtained during four revolutions in Spring and Summer 2004 of CXOGC J174540.0-290031, a moderately bright transient X-ray source, located at only 2.9" from SgrA*. We report the discovery of sharp and…

We report on the discovery with Chandra of a strong modulation (~90% pulsed fraction) at ~6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular…

Removing outbursts from multiwavelength light curves of the blazar Mrk~421, we construct outburstless time series for this system. A model-independent power spectrum light curve analysis in the optical, hard X-ray and gamma-rays for this…

We present XMM-Newton observations of the 569 sec period system RX J1914+24 (V407 Vul). This period is believed to represent the binary orbital period making it an ultra-compact binary system. By comparing the phase of the rise to maximum…

We investigate the formation and evolution of Ultra-Compact X-ray Binaries (UCXBs) using the COMPAS binary evolution code, starting from the Zero Age Main Sequence (ZAMS). Focusing on the low-mass MS companion channel, we simulate…

We report the discovery of the transient ultraluminous X-ray source (ULX) CXOU J122602.3+125951 (hereafter M86 tULX-1), located 3'52" (19 kpc) northwest of the centre of the giant elliptical galaxy M86 (NGC 4406) in the Virgo Cluster. The…