Related papers: A new candidate Wolf-Rayet X-ray binary in NGC 253
Transitional millisecond pulsars are millisecond pulsars that switch between a rotation-powered millisecond pulsar state and an accretion-powered X-ray binary state, and are thought to be an evolutionary stage between neutron star low-mass…
We present a detailed case study of the diffuse X-ray and H-alpha emission in the halo of NGC 253, a nearby edge-on starburst galaxy driving a galactic superwind. The arcsecond spatial resolution of the Chandra ACIS instrument allows us to…
Photometric observations of the supersoft X-ray source 1E 0035.4-7230 obtained during two years reveal that the very blue optical counterpart (V (maximum)=20.2, B-V=-0.15, U-B=-1.06) undergoes nearly sinusoidal variations with a period of…
We present comprehensive X-ray point source catalogs of NGC~55, NGC~2403, and NGC~4214 as part of the Chandra Local Volume Survey. The combined archival observations have effective exposure times of 56.5 ks, 190 ks, and 79 ks for NGC~55,…
We present an update of 3C 273's database hosted by the ISDC, completed with data from radio to gamma-ray observations over the last 10 years. We use this large data set to study the multiwavelength properties of this quasar,especially…
We present the first study of the X-ray sources in one of the most metal-rich globular clusters in the Galaxy, NGC 6528. Using relatively deep (66 ksec) archival imaging from the Chandra X-ray Observatory, we identify 18 sources within the…
We present some preliminary results from new Chandra and XMM-Newton X-ray observations of the nearby barred spiral galaxy NGC1672. It shows dramatic nuclear and extra-nuclear star formation activity, including starburst regions located near…
Here we report on joint X-ray and radio monitoring of the neutron star low-mass X-ray binary SAX J1810.8-2609. Our monitoring covered the entirety of its ~5 month outburst in 2021, revealing a temporal correlation between its radio and…
We report the results of a deep Chandra survey of the Sculptor dwarf spheroidal galaxy. We find five X-ray sources with $L_X$ of at least $6\times10^{33}$ ergs/sec with optical counterparts establishing them as members of Sculptor. These…
Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of ~ 10^15 eV. We report the detection of gamma rays -- tracers…
We investigate the nature of CXOU J005440.5-374320 (J0054), a peculiar bright ($\sim$$4\times10^{39}$ erg/s) and soft X-ray transient in the spiral galaxy NGC 300 with a 6-hour periodic flux modulation that was detected in a 2014 Chandra…
NGC300 X-1 and IC10 X-1 are currently the only two robust extragalactic candidates for being Wolf-Rayet/black hole X-ray binaries, the Galactic analogue being Cyg X-3. These systems are believed to be a late product of high-mass X-ray…
The XMM-Newton satellite has made four observations of the core of M31 as part of a survey that will span the entire galaxy. The majority of the X-ray emission is contributed by point sources, chiefly X-ray Binaries (XB). Exciting early…
We present an X-ray spectral and spatial analysis of the composite starburst/Seyfert galaxy NGC 1365. Excellent fits of the ROSAT PSPC spectrum are obtained by combining a soft thermal component with a hard powerlaw. The hard component may…
The classical nova V4743 Sgr was observed with XMM-Newton for about 10 hours on April 4 2003, 6.5 months after optical maximum. At this time, this nova had become the brightest supersoft X-ray source ever observed. We present the results of…
We report on the intriguing properties of a variable X-ray source projected at the outskirts of the elliptical galaxy NGC 6099 ($d \approx 139$ Mpc). If truly located near NGC 6099, this is a hyperluminous X-ray source that reached an X-ray…
The clumpy stellar wind from the companion star in high mass X-ray binaries causes variable, partial absorption of the emission from the X-ray source. We studied XMM-Newton observations from the 7.22 d-long "Cyg X-1 Hard state Observations…
We report here the discovery of NGC 7793 ULX-4, a new transient ultraluminous X-ray source (ULX) in NGC 7793, a spiral galaxy already well known for harbouring several ULXs. This new source underwent an outburst in 2012, when it was…
We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole…
The microquasar Cygnus X-3 was observed several times with the Gemini North Infrared Spectrograph while the source was in the hard X-ray state. We describe the observed 1.0-2.4 $\mu$m spectra as arising from the stellar wind of the…