Murchison widefield array observations of anomalous variability: a serendipitous night-time detection of interplanetary scintillation

Journal Article · Mon Aug 10 04:00:00 EDT 2015 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/809/1/L12· OSTI ID:22868714

Kaplan, D. L. ^[1]; Tingay, S. J.; Macquart, J. P.; Hancock, P.; Morgan, J.; Wayth, R. B.; Trott, C.; Kudryavtseva, N. ^[2]; Manoharan, P. K.; Oberoi, D. ^[3]; Mitchell, D. A.; Murphy, T. ^[4]; Ekers, R. D. ^[5]; Cairns, I. H. ^[6]; Feng, L. ^[7]; Bernardi, G. ^[8]; Bowman, J. D. ^[9]; Briggs, F. ^[10]; Cappallo, R. J. ^[11]; others, and

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1. Department of Physics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States)
2. International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia)
3. Radio Astronomy Centre, National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Ooty 643001 (India)
4. ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)(Australia)
5. CSIRO Astronomy and Space Science (CASS), P.O. Box 76, Epping, NSW 1710 (Australia)
6. Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)
7. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
8. SKA SA, 3rd Floor, The Park, Park Road, Pinelands 7405 (South Africa)
9. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
10. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)
11. MIT Haystack Observatory, Westford, MA 01886 (United States)

We present observations of high-amplitude rapid (2 s) variability toward two bright, compact extragalactic radio sources out of several hundred of the brightest radio sources in one of the 30{sup ∘}×30{sup ∘} Murchison Widefield Array (MWA) Epoch of Reionization fields using the MWA at 155 MHz. After rejecting intrinsic, instrumental, and ionospheric origins we consider the most likely explanation for this variability to be interplanetary scintillation (IPS), likely the result of a large coronal mass ejection propagating from the Sun. This is confirmed by roughly contemporaneous observations with the Ooty Radio Telescope. We see evidence for structure on spatial scales ranging from <1000 to >10{sup 6} km. The serendipitous night-time nature of these detections illustrates the new regime that the MWA has opened for IPS studies with sensitive night-time, wide-field, low-frequency observations. This regime complements traditional dedicated strategies for observing IPS and can be utilized in real-time to facilitate dedicated follow-up observations. At the same time, it allows large-scale surveys for compact (arcsec) structures in low-frequency radio sources despite the 2{sup ′} resolution of the array.

• OSTI ID: 22868714
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 809; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DETECTION
GALAXIES
HELIOSPHERE
MASS
MHZ RANGE
RADIO TELESCOPES
SCINTILLATIONS
SUN