* Astronomy

Title: Discovery of two pulsars towards the Galactic Centre
Authors: Simon Johnston, M. Kramer, D. R. Lorimer, A. G. Lyne, M. McLaughlin, B. Klein, R. N. Manchester

Researchers report the discovery of two highly dispersed pulsars in the direction of the Galactic Centre made during a survey at 3.1 GHz with the Parkes radio telescope. Both PSRs J1745-2912 and J1746-2856 have an angular separation from the Galactic Centre of less than 0.3 degrees and dispersion measures in excess of 1100 cm-3pc, placing them in the top 10 pulsars when ranked on this value.
The frequency dependence of the scatter-broadening in PSR J1746-2856 is much shallower than expected from simple theory.
They believe it likely that the pulsars are located between 150 and 500 pc from the Galactic Centre on the near side, and are part of an excess population of neutron stars associated with the Centre itself. A second survey made at 8.4 GHz did not detect any pulsars. This implies either that there are not many bright, long-period pulsars at the Galactic Centre or that the scattering is more severe at high frequencies than current models would suggest.


Image of the Galactic Centre region showing the surveyed regions and the profiles of the newly discovered pulsars. The background image shows continuum emission at a frequency of 10.55 GHz from the Effelsberg survey of Seiradakis et al. (1989).
The larger circles denote individual survey pointings at 3.1 GHz with the smaller circles representing the pointings for the 8.4 GHz survey. The two stars mark the positions of the discovered pulsars, with their respective pulse profiles shown at the top. Note that both pulsars lie outside the region surveyed both at 8.4 GHz and at 5 GHz with Effelsberg.

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