Limits on the Ultra-bright Fast Radio Burst Population from the CHIME Pathfinder

作者：Amiri M; Bandura K; Berger P; Bond J R; Cliche J F; Connor L; Deng M; Denman N; Dobbs M; Domagalski R S; Fandino M; Gilbert A J; Good D C; Halpern M; Hanna D; Hincks A D; Hinshaw G; Hofer C; Hsyu G; Klages P; Landecker T L; Masui K; Mena Parra J; Newburgh L B; Oppermann N; Pen U L; Peterson J B; Pinsonneault Marotte T; Renard A; Shaw J R; Siegel S R; Sigurdson K; Smith K; Storer E; Tretyakov I; Vanderlinde K

来源：Astrophysical Journal, 2017, 844(2): 161.

DOI：10.3847/1538-4357/aa713f

• instrumentation: interferometers
• pulsars: general

We present results from a new incoherent-beam fast radio burst (FRB) search on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder. Its large instantaneous field of view (FoV) and relative thermal insensitivity allow us to probe the ultra-bright tail of the FRB distribution, and to test a recent claim that this distribution's slope, alpha -partial derivative logN/partial derivative logS is quite small. A 256-input incoherent beamformer was deployed on the CHIME Pathfinder for this purpose. If the FRB distribution were described by a single power law with alpha = 0.7, we would expect an FRB detection every few days, making this the fastest survey on the sky at present. We collected 1268 hr of data, amounting to one of the largest exposures of any FRB survey, with over 2.4 x 10(5) deg(2) hr. Having seen no bursts, we have constrained the rate of extremely bright events to <13 sky(-1) day(-1) above similar to 220 root(tau/ms) Jy ms for tau between 1.3 and 100 ms, at 400-800 MHz. The non-detection also allows us to rule out alpha less than or similar to 0.9 with 95% confidence, after marginalizing over uncertainties in the GBT rate at 700-900 MHz, though we show that for a cosmological population and a large dynamic range in flux density, alpha is brightness dependent. Since FRBs now extend to large enough distances that non-Euclidean effects are significant, there is still expected to be a dearth of faint events and relative excess of bright events. Nevertheless we have constrained the allowed number of ultra-intense FRBs. While this does not have significant implications for deeper, large-FoV surveys like full CHIME and APERTIF, it does have important consequences for other wide-field, small dish experiments.

• 出版日期2017-8-1