PULSAR OBSERVATIONS OF EXTREME SCATTERING EVENTS

Journal Article · Sat Aug 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/808/2/113· OSTI ID:22525645

Coles, W. A. ^[1]; Kerr, M.; Shannon, R. M.; Hobbs, G. B.; Manchester, R. N.; Dai, S.; Ravi, V.; Reardon, D.; Toomey, L.; Zhu, X. J. ^[2]; You, X. -P. ^[3]; Bailes, M.; Straten, W. van ^[4]; Bhat, N. D. R. ^[5]; Burke-Spolaor, S. ^[6]; Keith, M. J. ^[7]; Levin, Y. ^[8]; Osłowski, S. ^[9]; Wang, J. B. ^[10]

---

1. ECE Department, University of California at San Diego, La Jolla, CA, 92093-0407 (United States)
2. ATNF, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)
3. Southwest University, Chongqing (China)
4. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia)
5. International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia)
6. California Institute of Technology, Pasadena, 1200 E California Boulevard, CA 91125 (United States)
7. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom)
8. Monash Center for Astrophysics, School of Physics and Astronomy, Monash University, Vic 3800 (Australia)
9. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
10. Xinjiang Astronomical Observatory, Chinese Academy of Science, 150 Science 1-Street, Urumqi, Xinjiang, 830011 (China)

Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage of a “diverging plasma lens” across the line of sight (LOS). Modeling the refraction of such a lens indicates that the structure size must be of the order of AU and the electron density of the order of 10s of cm{sup −3}. Similar structures have been observed in measurements of pulsar intensity scintillation and group delay. Here we report observations of two ESEs, showing increases in both intensity scintillation and dispersion made with the Parkes Pulsar Timing Array. These allow us to make more complete models of the ESE, including an estimate of the “outer-scale” of the turbulence in the plasma lens. These observations clearly show that the ESE structure is fully turbulent on an AU scale. They provide some support for the idea that the structures are extended along the LOS, such as would be the case for a scattering shell. The dispersion measurements also show a variety of AU scale structures that would not be called ESEs, yet involve electron density variations typical of ESEs and likely have the same origin.

• OSTI ID: 22525645
• Journal Information: Astrophysical Journal, Vol. 808, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ELECTROMAGNETIC LENSES
ELECTRON DENSITY
INTERGALACTIC SPACE
INTERSTELLAR SPACE
PLASMA
PULSARS
REFRACTION
SCATTERING
SCINTILLATIONS
TURBULENCE
VARIATIONS