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Luminosity Functions
X-Newsgroups: sci.astro.research
In-reply-to: In article , "PoorRichard" writes: My question is, what approach for computing a (meaningful) LF is best As it happens, I recently had to study LF calculations. The best single source I found was the paper by Willmer (1997, AJ, 114, 898). The bottom line is that there is no single "best" method. Questions to ask: how many objects in your sample? Are they clustered? Do you want to avoid binning the data? Are you willing to assume a Schechter function or other functional form? Among non-parametric methods, good old 1/V_max may be your only choice if you have fewer than a thousand objects, but it requires binning the data and is biased by clustering. If you have enough objects, the Lynden-Bell C- method avoids these problems. If you are willing to adopt a functional form in advance, maximum likelihood (such as the STY method) is the way to go. Ideally you would try more than one method and make sure they agree or at least that you understand why not if they don't. -- Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA (Please email your reply if you want to be sure I see it; include a valid Reply-To address to receive an acknowledgement. Commercial email may be sent to your ISP.) |
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