Related papers: Ultraluminous X-ray Sources in M51

The advanced capabilities of the Chandra and XMM-Newton observatories mean that, for the first time, the detailed study of the brightest point-like X-ray sources in nearby galaxies outside of the local group is a realistic aim. Here, we…

We report on \chandra observations of the central region of M31. By combining eight \chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central $\sim 17'\times17'$ region of M31, with a…

We present six monitoring observations of the starburst galaxy NGC 2146 using the Chandra X-ray Observatory. We have detected 67 point sources in the 8'.7 x 8'.7 field of view of the ACIS-S detector. Six of these sources were Ultra-Luminous…

With a Chandra ACIS-S3 observation, we detect 42 X-ray point sources in the elliptical galaxy NGC 720, including a possible central source. Most of these sources will be low-mass X-ray binaries (LMXBs), and 12 are located within 2" of…

We report on a powerful and variable off-nuclear X-ray source in the nearby spiral galaxy NGC 4945. Two ROSAT PSPC observations show the source to brighten in 0.5--2.0 keV flux by a factor of about 9 on a time-scale of 11 months or less. It…

The intense, bursting X-ray source in the globular cluster NGC 1851 was one of the first cluster sources discovered, but has remained optically unidentified for 25 years. We report here on results from Hubble Space Telescope WFPC2…

We observed the globular cluster NGC 6652 with Chandra for 47.5 ks, detecting six known X-ray sources, as well as five previously undetected X-ray sources. Source A (XB 1832-330) is a well-known bright low-mass X-ray binary (LXMB). The…

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…

We report the optical identifications of two X-ray luminous point sources in the spiral galaxy NGC4565 based on archive data of Chandra and the Hubble Space Telescope. The central X-ray point source, RXJ1236.3+2559, is found to be the…

We report the discovery of a new ultraluminous X-ray source (ULX) in the nearby galaxy NGC 4244 from Chandra archival data. The source, 1WGAJ1216.9+3743, is one of the least luminous and softest ULXs discovered so far. Its X-ray spectrum is…

We have spatially and spectrally resolved the sources of X-ray emission from the X-ray faint S0 galaxy NGC 1553 using an observation from the Chandra X-ray Observatory. The majority (70%) of the emission in the 0.3 - 10.0 keV band is…

We observed the nearby galaxy M~51 (NGC 5194) with BeppoSAX. The X-ray properties of the nucleus below 10 keV are almost the same as the ASCA results regarding the hard component and the neutral Fe K$\alpha$ line, but the intensity is about…

We present characteristics of the X-ray point source population in the M84 galaxy, observed by Chandra ACIS-S. We find an excess in the number of sources centered on M84, with a spatial distribution closely corresponding to the M84 stellar…

We observed the nearby, low-density globular cluster M71 (NGC 6838) with the Chandra X-ray Observatory to study its faint X-ray populations. Five X-ray sources were found inside the cluster core radius, including the known eclipsing binary…

We perform empirical fits to the \emph{Chandra} and \emph{XMM-Newton} spectra of three ultraluminous X-ray sources (ULXs) in the edge-on spiral galaxy NGC 891, monitoring the region over a seventeen year time window. One of these sources…

We report the detailed analysis of the X-ray properties of the discrete sources detected in a long (72 ks) \chandra ACIS-S observation of the Antennae galaxies. We detect 49 sources, down to a detection limit of ~ 10^{38} erg\s; 18 sources…

We present the X-ray source catalog for the Chandra monitoring observations of the elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501…

Despite the 30-year history of ultra-luminous X-ray sources (ULXs) studies, issues like the majority of their physical natures (i.e., neutron stars, stellar-mass black holes, or intermediate black holes) as well as the accretion mechanisms…

We report Chandra observations of the Scd galaxy NGC 2139, which is known to host a recently formed (10^7.6 yrs) nuclear star cluster. The star cluster is undetected in X-rays, with an upper bound on 0.5-7 keV luminosity of L_X < 7.1 x…

We present results from a 47 ks observation of the Andromeda galaxy, M31, using the High-Resolution Camera of the Chandra X-Ray Observatory. We detect 142 point sources spanning three orders of magnitude in luminosity, from $L_X = 2\times…