Related papers: Optical Constraints on an X-ray Transient Source i…
We report on multi-band observations of the transient source Swift J0840.7-3516, which was detected in outburst in 2020 February by the Neil Gehrels Swift Observatory. The outburst episode lasted just ~5 days, during which the X-ray…
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…
The purpose of this study is to explore the population of X-ray point sources in the bulge of M31, with the primary goal to contrast properties of various subpopulations, such as persistent and transient sources, primordial LMXBs and…
We present new Chandra X-ray observations of the transient black hole X-ray binary MAXI J1659-152 in quiescence. These observations were made more than one year after the end of the source's 2010-2011 outburst. We detect the source at a…
SAX J1711.6-3808 is an X-ray transient in the Galactic bulge that was active from January through May of 2001 and whose maximum 1-200 keV luminosity was measured to be 5X10-9 erg/s/cm2 which is less than ~25% of the Eddington limit, if…
We searched optical/UV/IR counterparts of seven supersoft X-ray sources (SSS) in M31 in the Hubble Space Telescope (HST) "Panchromatic Hubble Andromeda Treasury" (PHAT) archival images and photometric catalog. Three of the SSS were…
We have been regularly observing the bulge and inner disk of M31 for nearly 1 year, using both the HRC-I and ACIS-I instruments on the Chandra X-Ray Observatory. We present results from our program that are of interest to the study of the…
We report the discovery of a bright X-ray transient, CXOU J132527.6-430023, in the nearby early-type galaxy NGC 5128. The source was first detected over the course of five Chandra observations in 2007, reaching an unabsorbed outburst…
We report the discovery of a fairly bright transient during observations with the Wide Field Cameras on board the BeppoSAX satellite in September 1996. It was detected at a peak intensity of 0.1 Crab (2 to 10 keV) and lasted between 6 and…
We present detailed analysis of the transient X-ray source 2XMMi J003833.3+402133 detected by XMM-Newton in January 2008 during a survey of M 31. The X-ray spectrum is well fitted by either a steep power law plus a blackbody model or a…
This study represents the most sensitive Chandra X-ray point source catalogue of M31. Using 133 publicly available Chandra ACIS-I/S observations totalling ~1 Ms, we detected 795 X-ray sources in the bulge, northeast, and southwest fields of…
We have discovered with the Wide Field Cameras on board BeppoSAX the weak transient X-ray source SAXJ2239.3+6116 whose position coincides with that of 4U2238+60/3A2237+608 and is close to that of the fast transient AT2238+60 and the…
We have carried out an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115, using the Megasecond Chandra X-Ray Visionary Project observation (total exposure time 1.1 Ms). In total we found 136…
We present a systematic search for periodic X-ray sources in the bulge of M31, using ~ 2 Ms of archival Chandra observations spanning a temporal baseline of 16 years. Utilizing the Gregory-Loredo algorithm that is designed for…
We have identified four new black hole candidates in M31 globular clusters using 123 Chandra, and 4 XMM-Newton observations of the M31 central region. The X-ray source associated with Bo 163 (XB163) is a recurrent transient, with the…
(abridged) In the hunt for rare time-domain events, confusing exotic extragalactic phenomena with more common Galactic foreground events is an important consideration. We show how observations from multiple wavebands, in this case optical…
The X-ray source RX J004717.4-251811 in the nearby starburst galaxy NGC 253 was found to undergo changes from a low to a high state twice, during an XMM-Newton EPIC observation in December 2000 and also during a Chandra observation one year…
Context. X-ray binaries are usually divided in persistent and transient sources. For ultracompact X-ray binaries (UCXBs), the mass transfer rate is expected to be a strong function of orbital period, predicting persistent sources at short…
We report the identification of a bright hard X-ray source dominating the M31 bulge above 25 keV from a simultaneous NuSTAR-Swift observation. We find that this source is the counterpart to Swift J0042.6+4112, which was previously detected…
We report the detection of diffuse hot gas in M31, using archival Chandra observations which allow us to map out a 30' by 30' field (covering a galactocentric radius up to 4.5 kpc) and to detect sources in the galaxy down to a 0.5-8 keV…