|
|
Steve Willner wrote:
>The following is from memory without checking sources, so might be
>wrong:
>
>In the modern era, galaxy rotation curves came first, but hardly
>anybody believed them. I think the real "first" probably goes back
>to Zwicky and velocity dispersions in galaxy clusters. However, in
>both cases, the early measurements were so difficult and therefore
>few in number that it was easy to dismiss them as observational
>error.
>
>The breakthrough came with modern measurements of velocities in
>clusters; those could not be dismissed. Once the existence of dark
>matter was established, the galaxy rotation curves suddenly made
>sense, and modern instruments produced a lot more of them.
What's the timescale? I heard of the Milky Way rotation curve dilemma
while a student in U Md circa 1980. Leo Blitz had recently become a
professor there. The curve was consistent with observed mass
distribution near the center, but didn't fall off as 1/r outside the
observed mass, but remained flat. It was only one galaxy, but by 1980
this was well outside anything instrument error could produce.
I thought the cluster stuff was right after, ca mid-80s. But no...
earlier. A quick google for Fisher Tully gets most of it...
http://pluslucis.univie.ac.at/FBA/FBA99/Neho/3_1_3_.html
Die Methode wurde von R.B. Tully und J.R. Fischer in den spten
70'ern und 80'ern dieses Jahrhunderts fertig entwickelt. Seitdem wurde
diese Technik durch etliche andere Wissenschaftler verbessert und
ist nun eine etablierte Methode, um die Entfernung zu Spiralgalaxien
zu messen.
Absolute brightness and rotation velocity.
>cosmological measurements came relatively recently, mainly with
>the WMAP first release. They fully confirm the results from rotation
>curves and clusters and determine the fraction of dark matter that's
>baryonic.
That's really recent.
--
ciao,
Bruce
drift wave turbulence: http://www.rzg.mpg.de/~bds/
|
|