Selection functions in doppler planet searches

O'Toole, S. J. and Tinney, C. G. and Jones, H. R. A. and Butler, R. P. and Marcy, G. W. and Carter, B. D. and Bailey, J. (2009) Selection functions in doppler planet searches. Monthly Notices of the Royal Astronomical Society, 392 (2). pp. 641-654. ISSN 0035-8711

[img]
Preview
PDF (Accepted Version)
O'Toole_Tinney_Jones_Butler_Marchy_Carter_Bailey_AV.pdf

Download (1549Kb)

Abstract

We present a preliminary analysis of the sensitivity of Anglo-Australian Planet Search data to the orbital parameters of extrasolar planets. To do so, we have developed new tools for the automatic analysis of large-scale simulations of Doppler velocity planet search data. One of these tools is the two-dimensional Keplerian Lomb-Scargle (LS) periodogram that enables the straightforward detection of exoplanets with high eccentricities (something the standard LS periodogram routinely fails to do). We used this technique to redetermine the orbital parameters of HD20782b, with one of the highest known exoplanet eccentricities (e = 0.97 +/- 0.01). We also derive a set of detection criteria that do not depend on the distribution functions of fitted Keplerian orbital parameters (which we show are non-Gaussian with pronounced, extended wings). Using these tools, we examine the selection functions in orbital period, eccentricity and planet mass of Anglo-Australian Planet Search data for three planets with large-scale Monte Carlo like simulations. We find that the detectability of exoplanets declines at high eccentricities. However, we also find that exoplanet detectability is a strong function of epoch-to-epoch data quality, number of observations and period sampling. This strongly suggests that simple parametrizations of the detectability of exoplanets based on `whole-of-survey' metrics may not be accurate. We have derived empirical relationships between the uncertainty estimates for orbital parameters that are derived from least-squares Keplerian fits to our simulations and the true 99 per cent limits for the errors in those parameters, which are larger than equivalent Gaussian limits by the factors of 5-10. We quantify the rate at which false positives are made by our detection criteria, and find that they do not significantly affect our final conclusions. And finally, we find that there is a bias against measuring near-zero eccentricities, which becomes more significant in


Statistics for USQ ePrint 5770
Statistics for this ePrint Item
Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Pre-print template-style version deposited in accordance with the copyright policy of the publisher. The definitive version is available at www.blackwell-synergy.com.
Depositing User: Dr Brad Carter
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 17 Feb 2010 05:41
Last Modified: 02 Jul 2013 23:25
Uncontrolled Keywords: numerical methods; statistical methods; stars; individual; HD20782; HD38382; HD179949; planetary systems
Fields of Research (FOR2008): 09 Engineering > 0901 Aerospace Engineering > 090199 Aerospace Engineering not elsewhere classified
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: doi: 10.1111/j.1365-2966.2008.14051.x
URI: http://eprints.usq.edu.au/id/eprint/5770

Actions (login required)

View Item Archive Repository Staff Only