Arecibo Pulsar Survey using ALFA. III. Precursor survey and population synthesis
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Abstract
- The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32 degrees less than or similar to l less than or similar to 77 degrees and 168 degrees less than or similar to l less than or similar to 214 degrees) close to the Galactic plane (vertical bar b vertical bar less than or similar to 5 degrees) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo's unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in l and vertical bar b vertical bar less than or similar to 1 degrees) and detected 45 pulsars. Detections included 1 known millisecond pulsar and 11 previously unknown, long-period pulsars. In the surveyed part of the sky that overlaps with the Parkes Multibeam Pulsar Survey (36 degrees less than or similar to l less than or similar to 50 degrees), PALFA is probing deeper than the Parkes survey, with four discoveries in this region. For both Galactic millisecond and normal pulsar populations, we compare the survey's detections with simulations to model these populations and, in particular, to estimate the number of observable pulsars in the Galaxy. We place 95% confidence intervals of 82,000 to 143,000 on the number of detectable normal pulsars and 9000 to 100,000 on the number of detectable millisecond pulsars in the Galactic disk. These are consistent with previous estimates. Given the most likely population size in each case (107,000 and 15,000 for normal and millisecond pulsars, respectively), we extend survey detection simulations to predict that, when complete, the full PALFA survey should have detected 1000(-230)(+330) normal pulsars and 30(-20)(+200) millisecond pulsars. Identical estimation techniques predict that 490(-115)(+160) normal pulsars and 12(-5)(+70) millisecond pulsars would be detected by the beginning of 2014; at the time, the PALFA survey had detected 283 normal pulsars and 31 millisecond pulsars, respectively. We attribute the deficiency in normal pulsar detections predominantly to the radio frequency interference environment at Arecibo and perhaps also scintillation-both effects that are currently not accounted for in population simulation models.
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| File | Nice-AstrophysicalJournal-vol787-2014.pdf | Uploaded 2019-10-20 | Public | Download |
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