Related papers: A second neutron star in M4?
We present here the first convincing observational manifestation of a magnetar-like magnetic field in an accreting neutron star in binary system - the first pulsating ultra-luminous X-ray source X-2 in the galaxy M82. Using the Chandra…
In this study, we examine the properties of donor stars of the three recently discovered ultraluminous X-ray sources (ULXs) powered by rotating neutron stars. For this purpose, we constructed a theoretical relation between the X-ray…
We detect a gradual, long-term change in the shape of the X-ray spectrum of the isolated neutron star RX J0720.4-3125, such that the spectrum of the source can no longer be described as a blackbody spectrum. The change is accompanied by an…
We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4-650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of $\sim$20.1 (3300-10500 $\require{mediawiki-texvc} \AA$). The…
Chandra images of the elliptical galaxy NGC4261 have revealed an anisotropy in the spatial distribution of the off-nuclear X-ray sources, interpreted by Zezas et al. as evidence of an association with a young stellar population. Our…
The observed light curves and other properties of the two extragalactic fast x-ray transients, CDF-S XT1 and CDF-S XT2, which were discovered recently in archival data of the Chandra Deep Field-South (CDF-S) observations, indicate that they…
We studied the colliding galaxy NGC 7714 with two XMM-Newton observations, six months apart. The galaxy contains two bright X-ray sources: we show that they have different physical nature. The off-nuclear source is an accreting compact…
We observed with Chandra two peculiar galactic X-ray sources, 4U 1700+24 and 4U 1954+319, which are suspected to have a M-type giant star as optical counterpart, in order to get an high-precision astrometric position for both of them. The…
The quiescent spectrum of neutron star low-mass X-ray binaries typically consists of two components - a thermal component associated with emission from the neutron star surface, and a non-thermal power-law component whose origin is not well…
We present results from the first successful millimetre (combined 33 GHz and 35 GHz) observations of the neutron star X-ray binary Circinus X-1, using the Australia Telescope Compact Array. The source was clearly detected in all three…
We report on the discovery of a transient X-ray pulsars, located in the Small Magellanic Cloud, with a pulse period of 292 s. A series of Chandra pointings fortuitously recorded in 2010 April-May the occurrence of a two-weeks-long outburst,…
We present NuSTAR observations of Vela X-1, a persistent, yet highly variable, neutron star high-mass X-ray binary (HMXB). Two observations were taken at similar orbital phases but separated by nearly a year. They show very different 3-79…
Detailed modeling of the millisecond brightness oscillations during thermonuclear bursts from low mass X-ray binaries can provide important information about neutron star structure. Until now the implementation of this idea has not been…
We present a 10-year X-ray light curve and the spectra of a peculiar X-ray transient in the spiral galaxy M81. The source was below the detection limit of ROSAT PSPC before 1993, but it brightened substantially in 1993, with luminosities…
It has been suggested that most Be/X-ray binaries are low X-ray luminosity nearby objects, containing white dwarfs (Chevalier & Ilovaisky 1998). We show that existing evidence indicates that all known Be/X-ray binaries are relatively bright…
We report a Chandra ACIS-I observation of the dense globular cluster Terzan 5. The previously known transient low-mass x-ray binary (LMXB) EXO 1745-248 in the cluster entered a rare high state during our August 2000 observation,…
G315.4-2.3 is a young Galactic supernova remnant (SNR), whose identification as the remains of a Type-II supernova (SN) explosion has been debated for a long time. In particular, recent multi-wavelength observations suggest that it is the…
The features and make up of the population of X-ray sources in Galactic star clusters reflect the properties of the underlying stellar environment. Cluster age, mass, stellar encounter rate, binary frequency, metallicity, and maybe other…
We investigate the X-ray variability of the supergiant X-ray binary 4U 1907+09 using the new NuSTAR observation of 2024. The source had a relatively stable flux level during previous NuSTAR observations, but the flux varied significantly…
We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg^2 region around Sgr A* with a total exposure of 1.7 Ms, and…