相关论文: Deep Chandra X-ray Observations of Low Mass X-ray …

We report the results of spectral and temporal variability studies of the ultraluminous X-ray sources (ULXs) contained within the interacting pair of galaxies NGC 4485/4490, combining Chandra and XMM-Newton observations. Each of the four…

We report on Chandra observations of the bright ultra-luminous X-ray (ULX) source in NGC3921. Previous XMM observations reported in the literature show the presence of a bright ULX at a 0.5-10 keV luminosity of 2x10^40 erg/s. Our Chandra…

We report significant inhomogeneities in the projected two-dimensional (2D) spatial distributions of Low-Mass X-ray Binaries (LMXBs) and Globular Clusters (GCs) of the intermediate mass elliptical galaxy NGC4278. In the inner region of…

We present the first X-ray study of NGC6791, one of the oldest open clusters known (8 Gyr). Our Chandra observation is aimed at uncovering the population of close interacting binaries down to Lx ~ 1e30 erg/s (0.3-7 keV). We detect 86…

We present an updated catalog of X-ray point sources in the inner 500$\arcsec$ ($\sim$20 parsec) of the Galactic Center (GC), where the {\it nuclear star cluster} (NSC) stands, based on a total of $\sim$4.5 Ms of {\it Chandra} observations…

Low luminosity active galactic nuclei are more abundant and closer to us than the luminous ones but harder to explore as they are faint. We have selected the four sources NGC 315, NGC 4261, NGC 1275, and NGC 4486, which have been detected…

We present long term optical variability studies of bright X-ray sources in four nearby elliptical galaxies with {\it Chandra} Advanced CCD Imaging Spectrometer array (ACIS-S) and {\it Hubble Space Telescope (HST)} Advanced Camera for…

Luminous infrared galaxies (LIRGs), the most extreme star-forming galaxies in the nearby (D$<$30 Mpc) Universe, show a notable X-ray emission deficiency (up to a factor of $\sim$10) compared with predictions from scaling relations of…

Recent observations of galaxies continue to reveal new ultraluminous X-ray sources (ULXs), increasing their known population and improving the statistics needed to understand their nature. We study the ULX populations of NGC 4631 and NGC…

Ultraluminous X-ray Sources (ULXs) in globular clusters are low mass X-ray binaries that achieve high X-ray luminosities through a currently uncertain accretion mechanism. Using archival Chandra and Hubble Space Telescope observations, we…

We present the spectral analysis of an 87~ks \emph{XMM-Newton} observation of Draco, a nearby dwarf spheroidal galaxy. Of the approximately 35 robust X-ray source detections, we focus our attention on the brightest of these sources, for…

We have studied the X-ray point source population of Centaurus A (NGC 5128) using data from four archival CHANDRA observations. We detected 272 point-like X-ray sources within a radius of 10 arcmin from the centre. Approximately half of…

We used V and I CCD photometry to search for low-surface brightness dwarf galaxies (LSBD) in the central (<0.5 h^-1 Mpc) region of the groups NGC 6868, NGC 5846, HCG 42 and the poor cluster IC 4765. Using the parameters given by the…

We have used Chandra observations of eight bulge-less disk galaxies to identify new ultraluminous X-ray source (ULX) candidates, study their high mass X-ray binary (HMXB) population, and search for low-luminosity active galactic nuclei…

We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival {\it XMM-Newton}, {\it Chandra}, {\it Swift}, and {\it Hubble Space Telescope} ({\it HST})…

We present an analysis of the ultraluminous X-ray source (ULX) population in 75 Virgo cluster late-type galaxies, including all those with a star formation rate >~ 1 M_{sun}/yr and a representative sample of the less star-forming ones. This…

We report on Chandra X-ray observations of four candidate low-mass black hole (<10^6Msun) active galactic nuclei (AGNs) that have the estimated Eddington ratios among the lowest (~10^(-2)) found for this class. The aims are to validate the…

We present Sloan g and i imaging from the GMOS instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of…

We present the most likely optical counterparts of 113 X-ray sources detected in our Chandra survey of the central region of the Small Magellanic Cloud (SMC) based on the OGLE-II and MCPS catalogs. We estimate that the foreground…

We are conducting a search for supermassive black holes (SMBHs) with masses below 10^7 M_sun by looking for signs of extremely low-level nuclear activity in nearby galaxies that are not known to be AGNs. Our survey has the following…