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We report on the discovery of 41 new pulsating sources in the data of the Chandra Advanced CCD Imaging Spectrometer, which is sensitive to X-ray photons in the 0.3-10 keV band. The archival data of the first 15 years of Chandra observations were retrieved and analysed by means of fast Fourier transforms, employing a peak-detection algorithm able to screen candidate signals in an automatic fashion. We carried out the search for new X-ray pulsators in light curves with more than 50 photons, for a total of about 190,000 lightcurves out of about 430,000 extracted. With these numbers, the ChAndra Timing Survey at Brera And Roma astronomical observatories (CATS@BAR) - as we called the project - represents the largest ever systematic search for coherent signals in the classic X-ray band. More than 50 per cent of the signals were confirmed by further Chandra (for those sources with two or more pointings), XMM-Newton or ROSAT data. The period distribution of the new X-ray pulsators above about 2,000s resembles that of cataclysmic variables, while there is a paucity of sources with shorter period and low fluxes. Since there is not an obvious bias against these detections, a possible interpretation is in terms of a magnetic gating mechanism in accreting neutron stars. Finally, we note that CATS@BAR is a living project and the detection algorithm will continue to be routinely applied to the new Chandra data as they become public. Based on the results obtained so far, we expect to discover about three new pulsators every year.
Globular clusters host a variety of lower-luminosity ($L_X<10^{35}$ erg s$^{-1}$) X-ray sources, including accreting neutron stars and black holes, millisecond pulsars, cataclysmic variables, and chromospherically active binaries. In this paper, we p
We have obtained a series of deep X-ray images of the nearby galaxy M83 using Chandra, with a total exposure of 729 ks. Combining the new data with earlier archival observations totaling 61 ks, we find 378 point sources within the D25 contour of the
This study presents the final source catalog of the Chandra ACIS Survey of M33 (ChASeM33). With a total exposure time of 1.4 Ms, ChASeM33 covers ~70% of the D25 isophote (Rapprox4kpc) of M33 and provides the deepest, most complete, and detailed look
M33 contains a large number of emission nebulae identified as supernova remnants (SNRs) based on the high [S II]:Ha ratios characteristic of shocked gas. Using Chandra data from the ChASeM33 survey with a 0.35-2 keV sensitivity of about 2 x 10**34 er
The Chandra ACIS Survey of M33 (ChASeM33) has acquired 7 fields of ACIS data covering M33 with 200 ks of exposure in each field. A catalog from the first 10 months of data, along with archival Chandra observations dating back to the year 2000, is cur