The population of radio-loud stars has to date been studied primarily through either targeted observations of a small number of highly active stars or wide-field, single-epoch surveys that cannot easily distinguish stellar emission from background extragalactic sources. As a result it has been difficult to constrain population statistics such as the surface density and fraction of the population producing radio emission in a particular variable or spectral class. In this paper, we present a sample of 36 radio stars detected in a circular polarization search of the multi-epoch Variables and Slow Transients (VAST) pilot survey with ASKAP at 887.5 MHz. Through repeat sampling of the VAST pilot survey footprint we find an upper limit to the duty cycle of M-dwarf radio bursts of $8.5 \,\rm {per\,cent}$, and that at least 10 ± 3 $\rm {per\,cent}$ of the population should produce radio bursts more luminous than $10^{15} \,\rm {erg}\mathrm{s}^{-1} \,\mathrm{Hz}^{-1}$. We infer a lower limit on the long-term surface density of such bursts in a shallow $1.25 \,\mathrm{m}\rm {Jy}\rm\ {PSF}^{-1}$ sensitivity survey of ${9}^{\, +{11}}_{-{7}}\times 10^{-3}$ $\,\deg ^{-2}$ and an instantaneous radio star surface density of 1.7 ± 0.2 × 10−3 $\,\deg ^{-2}$ on 12 min time-scales. Based on these rates we anticipate ∼200 ± 50 new radio star detections per year over the full VAST survey and ${41\, 000}^{\, +{10\, 000}}_{-{9\, 000}}$ in next-generation all-sky surveys with the Square Kilometre Array.
We present the detection of 661 known pulsars observed with the Australian SKA Pathfinder (ASKAP) telescope at 888 MHz as part of the Rapid ASKAP Continuum Survey (RACS). Detections were made through astrometric coincidence and we estimate the false alarm rate of our sample to be ∼0.5%. Using archival data at 400 and 1400 MHz, we estimate the power-law spectral indices for the pulsars in our sample and find that the mean spectral index is −1.78 ± 0.6. However, we also find that a single power law is inadequate for modeling all the observed spectra. With the addition of flux densities between 150 MHz and 3 GHz from various imaging surveys, we find that up to 40% of our sample show deviations from a simple power-law model. Using Stokes
- NSF-PAR ID:
- 10467641
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 956
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 28
- Size(s):
- ["Article No. 28"]
- Sponsoring Org:
- National Science Foundation
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