SIX NEW RECYCLED GLOBULAR CLUSTER PULSARS DISCOVERED WITH THE GREEN BANK TELESCOPE

Journal Article · Mon Jun 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/734/2/89· OSTI ID:21576635

Lynch, Ryan S ^[1]; Ransom, Scott M ^[2]; Freire, Paulo C. C. ^[3]

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1. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
2. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-4325 (United States)
3. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

We have completed sensitive searches for new pulsars in seven globular clusters using the Robert C. Byrd Green Bank Telescope, and have discovered six new recycled pulsars (four in NGC 6517 and two in M22), five of which are fully recycled millisecond pulsars with P < 10 ms. We report full timing solutions for all six new pulsars and provide estimates of their flux densities and spectral indices. None of the pulsars is detected in archival Chandra data down to L{sub X} {approx} 10{sup 32} erg s{sup -1} for NGC 6517 and L{sub X} {approx} 10{sup 31} erg s{sup -1} for M22. One of the millisecond pulsars in M22 appears to have a very low mass companion, and is likely a new 'black widow'. A second binary pulsar in NGC 6517 is in a long-period, mildly eccentric orbit. We are able to set some lower limits on the age of the system, and find that it may be less than a few hundred million years old, which would indicate recent pulsar recycling in NGC 6517. An isolated pulsar in NGC 6517 that lies about 20 core radii from the cluster center appears to have been ejected from the core by interacting with a massive binary. By analyzing the luminosity function of the pulsars in NGC 6517, we predict the cluster to harbor roughly a dozen pulsars. We use the observed period derivatives of three pulsars to set lower limits on the mass-to-light ratios in the cores of their host clusters, and find no evidence for large amounts of low-luminosity matter. We also discuss reasons for non-detections in some of the clusters we searched.

• OSTI ID: 21576635
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 734; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC RADIO SOURCES
FLUX DENSITY
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PULSARS
STAR CLUSTERS