Daily Image
07-12-2010
Lifting the veil on millisecond pulsars in our Galaxy
| Submitter: | Jason Hessels |
| Description: | Millisecond pulsars are hard to find. Not only are they weak, but their signals are often modulated by motion around a companion star. Until recently, one of the biggest challenges in finding millisecond pulsars was knowing where to look. All-sky surveys have found a few dozen millisecond pulsars, but such surveys are necessarily shallow and miss many interesting sources. Globular clusters are known to contain many millisecond pulsars, but these are for the most part quite distant and sometimes obscured by gas in the Galactic Plane. With the advent of the Fermi gamma-ray telescope, we now have a much better idea of where to focus our search efforts. It is now clear that many of the gamma-ray sources detected by Fermi are previously unknown pulsars, a good fraction of which are millisecond pulsars. With the Fermi catalogue of unidentified gamma-ray sources as our guide, we have been searching for millisecond pulsars with the 100-m Green Bank Telescope at 350MHz. So far, we have discovered 10 millisecond pulsars and confirmed one other recent discovery. Six of these new pulsars were discovered using the ASTRON Astronomy Group's "Drop" computer cluster. Given that the total known population of millisecond pulsars in the Galactic field (outside of globular clusters) is still less than 100, this survey has been a real jackpot in terms of its discovery rate. These new pulsars will undoubtedly shed light on the nature of Galactic gamma-ray sources and are likely very interesting pulsars in their own right. Shown in the center of the image is the Fermi gamma-ray sky, with the 10 pulsars circled. In some cases you can even see the associated gamma-ray point source if you squint. Above and below this are the cumulative pulse profiles of these pulsars, repeated twice for clarity. |
| Copyright: | JWTH/Fermi |
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