Initial Results from the ALFABURST Survey
Mayuresh Surnis, Griffin Foster, Golnoosh Golpayegani, Aris Karastergiou, Duncan Lorimer, Jayanth Chennamangalam, Kaustubh Rajwade, Maura McLaughlin, Devansh Agarwal, Wes Armour, Dan Werthimer, Jeff Cobb, Andrew Siemion, David MacMahon, Deepthi Gorthi, Xin Pei
aa r X i v : . [ a s t r o - ph . H E ] O c t Pulsar Astrophysics - The Next 50 YearsProceedings IAU Symposium No. 337, 2017P. Weltevrede, B.B.P. Perera, L. Levin Preston & S. Sanidas, eds. c (cid:13) Initial Results from the ALFABURSTSurvey
M. P. Surnis , G. Foster , , G. Golpayegani , A. Karastergiou , D.Lorimer , J. Chennamangalam , K. Rajwade , M. McLaughlin , D.Agarwal , W. Armour , D. Werthimer , J. Cobb , A. Siemion , D.MacMahon , D. Gorthi and Pei Xin West Virginia University, Morgantown, WV, USA.email: [email protected] University of Oxford, Oxford, UK. University of California, Berkeley, CA, USA. XinjiangAstronomical Observatory, Urumqi, Xinjiang, China.
Abstract.
Here, we present initial results from the ALFABURST radio transient survey, whichis currently running in a commensal mode with the ALFA receiver at the Arecibo telescope. Weobserved for a total of 1400 hours and have detected single pulses from known pulsars but didnot detect any FRBs. The non-detection of FRBs is consistent with the current FRB sky rates.
Keywords. surveys, (stars:) pulsars: general, methods: data analysis
1. Introduction
Fast Radio Bursts (FRBs) are millisecond duration, intense bursts of radio emissionoriginating at cosmological distances. To date, 23 FRBs have been detected [for an up-to-date list, see Petroff et al. (2016)] with one [FRB 121102; Spitler et al. (2014)], show-ing multiple bursts. The singular occurrence of most FRBs makes real-time detectionand follow-up essential in order to achieve accurate localizations and to identify multi-wavelength counterparts.ALFABURST is a commensal backend on the Arecibo L-band Feed Array (ALFA).It carries out real-time transient detection using a dedicated high performance comput-ing configuration with field programmable gate arrays and graphics processing units. Itprocesses 56 MHz bandwidth from each of the seven beams of the ALFA band with asampling time of 256 µ s.
2. Transient Detection Pipeline
ALFABURST is a component of SETIBURST (Chennamangalam et al. − − . The de-dispersed time series for each trial DM are then smoothed to fac-tors of 2 −
16 in powers of 2. The smoothed time series are then searched for individualevents crossing the threshold of 10 times the noise rms. Candidate FRBs are then passedto a coincidence filter, eliminating events seen in more than 3 beams simultaneously anda list of candidates along with the filterbank data for each candidate are saved to a localdisk for further scrutiny. We are currently working on developing an artificial intelligencealgorithm to categorize candidates automatically.1 Surnis et al.
Figure 1.
Left:
Single pulse detected from PSR B1900+01. The grayscale plot shows thetime-frequency structure while the bottom panel shows the pulse in the time series.
Right:
Surveysensitivity (dark gray) as a function of pulse width. Automated RFI excision excludes narrowin width, bright FRBs such as FRB150807 (light gray). Previously detected FRBs from Parkes(triangles), GBT (circle), Arecibo (diamond), UTMOST (pentagons), and ASKAP (hexagon)are plotted for reference.
3. Results and Discussion
We did not detect any FRBs in the data taken through June 2017, with about 1400hours of observing time. We have detected single pulses from known pulsars (see left panelin Figure 1 for an example) in the observed region. We estimate the nominal sensitivityof the survey to be about 70 mJy for a pulse width of 10 ms. Figure 1 (right panel)shows the sensitivity as a function of pulse width along with the 23 known FRBs for acomparison. Assuming the standard candle model (Lorimer et al. − per galaxy per year (Thornton et al. References
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