Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray Pulsars

We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg2 region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb-Scargle and epoch-foldin...

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Bibliographic Details
Published in:The Astrophysical journal 2017-09, Vol.847 (1), p.26
Main Authors: Hong, JaeSub, Antoniou, Vallia, Zezas, Andreas, Haberl, Frank, Sasaki, Manami, Drake, Jeremy J., Plucinsky, Paul P., Laycock, Silas
Format: Article
Language:English
Subjects:
ABSORPTION
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Blackbody
CORRELATIONS
COSMIC X-RAY SOURCES
ENERGY DEPENDENCE
LUMINOSITY
MAGELLANIC CLOUDS
Magnetars
MASS
MODULATION
NEUTRON STARS
PERIODICITY
PHOTONS
Polls & surveys
Power law
PULSARS
pulsars: general
Pulsation
PULSATIONS
SIMULATION
Spectral analysis
Spectrum analysis
stars: neutron
X RADIATION
X ray binaries
X ray spectra
X ray stars
X-ray fluxes
X-rays: binaries
XMM (spacecraft)
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Summary:We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg2 region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb-Scargle and epoch-folding techniques, we detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covered 11 other pulsars with no clear sign of periodic modulation. The 0.5-8 keV X-ray luminosity (LX) of the pulsars ranges from 1034 to 1037 erg s−1 at 60 kpc. All of the Chandra sources with LX 4 × 1035 erg s−1 exhibit X-ray pulsations. The X-ray spectra of the SMC pulsars (and high-mass X-ray binaries) are in general harder than those of the SMC field population. All but SXP 8.02 can be fitted by an absorbed power-law model with a photon index of Γ 1.5. The X-ray spectrum of the known magnetar SXP 8.02 is better fitted with a two-temperature blackbody model. Newly measured pulsation periods of SXP 51.0, SXP 214, and SXP 701, are significantly different from the previous XMM-Newton and RXTE measurements. This survey provides a rich data set for energy-dependent pulse profile modeling. Six pulsars show an almost eclipse-like dip in the pulse profile. Phase-resolved spectral analysis reveals diverse spectral variations during pulsation cycles: e.g., for an absorbed power-law model, some exhibit an (anti)-correlation between absorption and X-ray flux, while others show more intrinsic spectral variation (i.e., changes in photon indices).
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa8953