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

Abstract

We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We have analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg${}^2$ region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb-Scargle and epoch folding techniques, we have detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covers 11 other pulsars with no clear sign of periodic modulation. The 0.5-8 keV X-ray luminosity ($L_X$) of the pulsars ranges from $10^{34}$ to $10^{37}$ erg s${}^{-1}$ at 60 kpc. All the Chandra sources with $L_X$ $\gtrsim 4\times 10^{35}$ 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 $\Gamma$ $\lesssim$ 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 variation during pulsation cycle: 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.

arXiv comment24 pages, 19 figures, 11 tables, submitted to ApJ

References in corpus (56)

• On the Absorption of X-rays in the Interstellar Medium
• Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations
• A Wavelet-Based Algorithm for the Spatial Analysis of Poisson Data
• The Star Formation History of the Small Magellanic Cloud
• Assessing statistical significance of periodogram peaks
• The XMM-Newton serendipitous survey. VII. The third XMM-Newton serendipitous source catalogue
• Bayesian Estimation of Hardness Ratios: Modeling and Computations
• Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars
• Innovations in the Analysis of Chandra-ACIS Observations
• Theory of quasi-spherical accretion in X-ray pulsars
• NuSTAR discovery of a 3.76-second transient magnetar near Sagittarius A*
• Magnetically Torqued Thin Accretion Disks
• High-Mass X-ray binaries in the Small Magellanic Cloud
• Two Populations of X-ray Pulsars Produced by Two Types of Supernovae
• Star formation history and X-ray binary populations: the case of the Small Magellanic Cloud
• New spectral classification technique for X-ray sources: quantile analysis
• Spin period change and the magnetic fields of neutron stars in Be X-ray binaries in the Small Magellanic Cloud
• The XMM-Newton survey of the Small Magellanic Cloud: The X-ray point-source catalogue
• X-ray observations of Be/X-ray binaries in the SMC
• Star-formation history and X-ray binary populations: the case of the Large Magellanic Cloud
• A Long Look at the Be/X-Ray Binaries of the Small Magellanic Cloud
• Catalogue of Be/X-ray binary systems in the Small Magellanic Cloud: X-ray, optical & IR properties
• High mass X-ray binaries in the SMC: the luminosity function
• Very Long-term Optical Variability of High Mass X-ray Binaries in the SMC
• Long Term Behavior of X-ray Pulsars in the Small Magellanic Cloud
• The Magellanic Quasars Survey. III. Spectroscopic Confirmation of 758 AGNs Behind the Magellanic Clouds
• Discovery of a Possible Anomalous X-ray Pulsar in the Small Magellanic Cloud
• A Comprehensive Library of X-ray Pulsars in the Small Magellanic Cloud: Time Evolution of their Luminosities and Spin Periods
• Chandra Multiwavelength Plane (ChaMPlane) Survey: an Introduction
• Quantifying the Drivers of Star Formation on Galactic Scales. I. The Small Magellanic Cloud
• On the nature of `off' states in slowly rotating low-luminosity X-ray pulsars
• The origin of long-period X-ray pulsars
• Exploring the Small Magellanic Cloud to the Faintest X-ray Fluxes: Source Catalog, Timing and Spectral Analysis
• XMM-Newton observations of CXOU J010043.1-721134: the first deep look at the soft X-ray emission of a magnetar
• SXP 5.05 = IGR J00569-7226 : using X-rays to explore the structure of a Be stars circumstellar disk
• Dominance of Magnetic Cataclysmic Variables in the Resolved Galactic Ridge X-ray Emission of the Limiting Window
• Spin-Down of the Long-Period Accreting Pulsar 4U 2206+54
• Three New Long Period X-ray Pulsars Discovered in the Small Magellanic Cloud
• Discovery of the Slowest X-Ray Pulsar in the SMC, AX J0049.5-7323, with ASCA
• Discovery of a Significant Magnetic CV Population in the Limiting Window
• Signs of magnetic accretion in young Be/X-ray pulsar SXP 1062
• The XMM-Newton survey of the Small Magellanic Cloud: XMMUJ005011.2-730026 = SXP214, a Be/X-ray binary pulsar
• Photometric Periodicities of Be/X-ray Pulsars in the Small Magellanic Cloud
• Two long-period X-ray pulsars detected in the SMC field around XTE J0055-727
• Discovery of 16.6 and 25.5 s Pulsations from the Small Magellanic Cloud
• Discovery of 172-s Pulsations from a Be/X-ray Binary Candidate AX J0051.6-7311 in the SMC with ASCA
• Periodic Optical Outbursts from the Be/Neutron Star Binary AX J0049.4-7323
• A new look at the origin of the 6.67\,hr period X-ray pulsar 1E~161348-5055
• XMM-Newton observations of the Small Magellanic Cloud: XMMU J004814.1-731003, a 25.55 s Be/X-ray binary pulsar
• XMM-Newton Observations of Young and Energetic Pulsar J2022+3842
• INTEGRAL observations of the Small Magellanic Cloud
• On the spin-down mechanism of the X-ray pulsar 4U 2206+54
• Chandra Discovery of an Intermediate Polar in Baade's Window
• X-ray and optical study of the new SMC X-ray binary pulsar system SXP7.92 and its probable optical counterpart, AzV285
• SXP214, an X-ray Pulsar in the Small Magellanic Cloud, Crossing the Circumstellar Disk of the Companion
• Retrograde wind accretion -- an alternative mechanism for long spin-period of SFXTs

Cited by in corpus (8)

• Deep Chandra survey of the Small Magellanic Cloud. III. Formation efficiency of High-Mass X-ray binaries
• The First Year of S-CUBED: The Swift Small Magellanic Cloud Survey
• dart_board: Binary Population Synthesis with Markov Chain Monte Carlo
• Discovery of Shocked Molecular Clouds Associated with the Shell-Type Supernova Remnant RX J0046.5$-$7308 in the Small Magellanic Cloud
• Neutron Stars and Black Holes in the Small Magellanic Cloud: The SMC NuSTAR Legacy Survey
• The TRAPUM Small Magellanic Cloud pulsar survey with MeerKAT: I. Discovery of seven new pulsars and two Pulsar Wind Nebula associations
• In-depth study of long-term variability in the X-ray emission of the Be/X-ray binary system AX J0049.4-7323
• Synchrotron emission from the depths of pulsar magnetospheres