Searches for radio pulsations from the 3.76 second NuSTAR X-ray pulsar in the Galactic centre.

ATel #5027; Ralph Eatough (Max-Planck-Institut fuer Radioastronomie: MPIfR), Ramesh Karuppusamy (MPIfR), Michael Kramer (MPIfR), Alex Kraus (MPIfR), Bernd Klein (MPIfR), David Champion (MPIfR), Joris Verbiest (MPIfR), Patrick Lazarus (MPIfR), Paulo Freire (MPIfR), Andreas Brunthaler (MPIfR), Heino Falcke (ASTRON, Nijmegen)
on 29 Apr 2013; 16:54 UT
Credential Certification: Andreas Brunthaler (brunthal@mpifr-bonn.mpg.de)

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Following the recent discovery of 3.76 second pulsations in the Sgr A* region by the NuSTAR X-ray telescope (Atel #5020), we have conducted deep radio pulsar searches of the area. Observations have been performed with the Max-Planck-Institut fuer Radioastronomie (MPIfR) Effelsberg radio telescope at frequencies of 4.85 GHz (FWHM=146") and 14.6 GHz (FWHM=51"). High observing frequencies were chosen in order to mitigate the expected strong interstellar scattering in the Galactic centre region. Using cryogenically cooled receivers (system temperatures of 27 K at 4.85 GHz and 50 K at 14.6 GHz) we recorded summed polarisations for 128 spectral channels, across a bandwidth of 500 MHz, and with a data sampling interval of ~65 microseconds. Integration times of approximately one hour were performed at each frequency. No radio pulsations have been detected. For a 10 sigma pulse detection, and assuming a 10% pulse duty cycle, we derive upper limits on the flux density of pulsars of ~0.03 mJy and ~0.08 mJy at 4.85 GHz and 14.6 GHz respectively. We note the possibility of low-level terrestrial radio interference in our data. Sgr A* skims the horizon at the telescope site, making these observations susceptible to interference in the main beam of the telescope. As such we encourage further radio pulsar searches, at these frequencies and others.