http://arxiv.org/abs/1604.06328
Determining the near-Earth asteroids (NEAs) population is the focus of intense research, with the most recent models converging to a population of approximately 1,000 km-sized NEAs and up to approximately $10^8$ NEAs with absolute magnitude $H<28$. Here we show that the NEAs population is significantly smaller than previous estimates, with $900 \pm 10$ NEAs larger than 1 km, approximately 10% lower than most recent estimates. Additionally, we estimate the population of small NEAs at 430,000 $\pm$ 30,000 for $H<28$, a decrease by two orders of magnitude. These results are enabled by an analysis of the combined observations of nine of the leading asteroid surveys over the past two decades. This reduced population tracks very accurately the orbital distribution of recently discovered large NEAs, and produces an estimated Earth impact rate for small NEAs in good agreement with the bolide data. Data hint at a possible decrease of the average albedo in small NEAs that would reconcile the small difference between predicted bolide rates and observations, as well as explain the dip in the size-frequency distribution at a size of approximately 100 m. These results bring to focus the current status of the NEAs search activities, as we are in the endgame stage for larger NEAs, and knowing the statistical orbital distribution of the remaining asteroids will facilitate the development of optimal search strategies for current and future surveys.
P. Tricarico
Fri, 22 Apr 16
47/54
Comments: 19 pages, 1 table, 10 figures, comments welcome
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