相关论文: Ultraluminous X-ray sources out to z~0.3 in the CO…

This paper presents a comprehensive X-ray and multi-wavelength study of ultraluminous X-ray sources (ULXs) in NGC 1566 using archival Chandra, Swift/XRT, James Webb Space Telescope, JWST, and Hubble Space Telescope, HST observations. The…

We present highlights from a study of a sample of 10 extreme-luminosity candidate ultraluminous X-ray sources (L_X > 5 x 10^(40) erg sec^(-1)), all at distances < 100 Mpc, identified from a cross-correlation of the RC3 catalogue of galaxies…

Ultra-luminous X-ray sources (ULXs) are off-nuclear point sources in nearby galaxies with luminosities well exceeding the Eddington limit for stellar-mass objects. It has been recognized after the discovery of pulsating ULXs (PULXs) that a…

Following a serendipitous detection with the NuSTAR observatory, we present a multi-epoch spectral and temporal analysis of an extreme ultraluminous X-ray source (ULX) located in the outskirts of the Circinus galaxy, hereafter Circinus…

We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are located in and…

Recent Chandra and XMM-Newton surveys have confirmed that the cosmic X-ray background is mostly due to accretion onto super-massive black holes, integrated over cosmic time. Here we review the results obtained from the photometric and…

Hyper-luminous X-ray sources (HLXs; L_X>10^41 erg s^-1) are off-nuclear X-ray sources in galaxies and strong candidates for intermediate-mass black holes (IMBHs). We have constructed a sample of 169 HLX candidates by combining X-ray…

Ultraluminous X-ray sources (ULXs) with Lx > 10^{39} ergs/s have been discovered in great numbers in external galaxies with ROSAT, Chandra, and XMM. The central question regarding this important class of sources is whether they represent an…

Ultraluminous X-ray sources are non-nuclear point sources exceeding the Eddington luminosity of a 10 Solar mass black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or…

We have identified a large-scale structure at z~0.73 in the COSMOS field, coherently described by the distribution of galaxy photometric redshifts, an ACS weak-lensing convergence map and the distribution of extended X-ray sources in a…

X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). The XXL Survey spans two fields of a combined 50 $deg^2$ observed for more than 6Ms with XMM-Newton, occupying…

We use the new 4 Ms exposure of the CDF-S field obtained with the Chandra X-ray satellite to investigate the properties of the faintest X-ray sources over a wide range of redshifts. We use an optimized averaging procedure to investigate the…

Ultraluminous X-ray sources (ULXs) are a class of accreting compact objects with X-ray luminosities above 10$^{39}$ erg s$^{-1}$. The average number of ULXs per galaxy is still not well constrained, especially given the uncertainty on the…

We report on the stellar content, half-light radii and star formation rates of a sample of 10 known high-redshift ($z\gtrsim 2$) galaxies selected on strong neutral hydrogen (HI) absorption (log(N(HI)/cm$^{-2})>19$) toward background…

With recent Chandra observations, at least 60% of the 2-10 keV background is now resolved into discrete sources. Here we present deep optical, NIR, submm, and 20 cm (radio) images, as well as high-quality optical spectra, of a complete…

A number of ultraluminous X-ray sources (ULXs) are physically associated with extragalactic globular clusters (GCs). We undertake a systematic X-ray analysis of eight of the brightest of these sources. We fit the spectra of the GC ULXs to…

ULX-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ultraluminous X-ray source, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We…

In this Paper we report the discovery of CXO J122518.6+144545; a peculiar X-ray source with a position 3.6+-0.2",off-nuclear from an SDSS DR7 z=0.0447 galaxy. The 3.6" offset corresponds to 3.2 kpc at the distance of the galaxy. The 0.3-8…

We present the X-ray spectral analysis of the 1855 extragalactic sources in the Chandra COSMOS-Legacy survey catalog having more than 30 net counts in the 0.5-7 keV band. 38% of the sources are optically classified Type 1 active galactic…

We discuss ROSAT HRI X-ray observations of 33 very nearby galaxies, sensitive to X-ray sources down to a luminosity of approximately 10^38 erg/s. The galaxies are selected from a complete, volume limited sample of 46 galaxies with d<7 Mpc…