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Detection of pulsation from Swift J0513.4-6547 with Fermi/GBM

ATel #2023; Mark H. Finger (USRA), Elif Beklen (METU)
on 18 Apr 2009; 01:45 UT
Credential Certification: Dr. Mark H. Finger (Mark.Finger@msfc.nasa.gov)

Subjects: Binary, Transient, Pulsar

Pulsations from the recently discovered accreting pulsar Swift J0513.4-6547 in the LMC (H. A. Krim et al. ATEL #2011) have been detected in the Fermi/GBM rates between 2009 March 1 and March 28. Pulse searches were made for several multi-day intervals covering January 30 to April 15. The searches included both trial frequencies near the 36.66 mHz (27.28 s period) RXTE measurement (ATEL #2011), and trial frequency rates in the range expected for accreting pulsars near Eddington luminosity. The intervals with detections were:

  
Time Range           Epoch       Frequency   Frequency Rate   
   (MJD)             (MJD)        (mHz)       (1E-12 Hz/s)  
54819.0-54897.0    54893.984    36.59407(13)    48(2)      
54897.0-54902.0    54899.339    36.62742(18)   102(5)   
54904.6-54908.5    54906.509    36.67029(15)    30(3)  
54908.5-54912.5    54910.552    36.67429(13)    -8(3)  
54912.5-54918.0    54915.296    36.66989(13)    -6(3)   
These times, frequencies, and frequency rates are barycentric. A plot may be seen at http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/swiftj0513_fig1.png The pulsed flux (mean-minimum 12-25 keV) reached 15 mCrab between March 18 and March 22, giving a lower limit to the luminosity of 7E+37 erg/cm^2 s. The frequency rate in the second detection interval is consistent with a pulsar accreting from a disk near the Eddington rate. The negative frequency rates in the last two intervals are likely due to Doppler shifts from the (unknown) binary orbit.

GBM Pulsar Project