The Mass has to do with?• Mass implies light

• More mass, the more light.

• A detailed calculation shows the relation is that the Luminosity is proportional to the v4

cf. http://www.aoc.nrao.edu/~smyers/courses/astro12/tully.html

TheTully-Fisher Relation

The S-Z (Sunyaev-Zel’dovich Effect) Concept:

Hot gas in Cluster changes CMB by about 1/1000

Now you see the effect

Now you don’t see the effect

The S-Z (Sunyaev-Zel’dovich Effect) Problems: Need to measure the gas temperature and distribution. This requires sophisticated X-ray telescopes in space and accurate modeling.

Now the “claim to fame” is the effect can be used to detect clusters of galaxies better than any other technique because it is a surface brightness effect which is independent of distance

Motivation for the SZ and Grav. Lens approaches used to be to measure H0.

Now mainly use SZ to discover clusters and

Grav. Lenses for statistical inferences about geometry of the universe:e.g. number of lenses found.

For, with Cepheids from HIPPARCOS, we’re pretty confident the right answer is 68 5 km/(sec-Mpc);

From J. Mould and 59 6 from Sandage => when doing something quick use 50,but for better number use 65

±±

Measuring Redshifts in real life =>

From Jim Schombert

Calibration source

Light from galaxy

Elliptical galaxy

This is not easy!Data

Result of matching a “template” to the data. “High” is good

Where are H & K???

Redder->

Higher z = redder

History of Hubble Constant

Sandage & Tamann

de Vaucouleurs; then Aaronson, Mould and Huchra

Sandage:

I told you so!!!

Summary:

Use a “ruler” (Radar) to measure distance to the sun

Use Parallax to measure distance to Cepheids

Use Super Novae, Tully-Fisher and Jackson-Faber/Fundamental plane to work our way out

Once we get out to about z = 0.1 we’re done as far as measuring H0

We can study the local motions versus distance and search for mass concentrations to directly determine m

Most famous “local” ( D = 42h-1Mpc) mass concentration (the Great Attractor)

Found with Tully-Fisher plus Jackson-Faber

The Great Attractor:Mass concentration of about 1016-1017 solar masses

(remember how much mass is in a cluster?)

inside a volume about 3 times that of a typical cluster of galaxies at about z = 0.014.We can’t see it directly

only its effect due to gravity. Close enough and concentrated enough that if it were “only” a concentration of galaxies we could see it. => Direct evidence for Dark Matter.

GA, cont.

© Kraan-Korteweg & Lahav, 1998, Scientific American 279, p.50

http://mensa.ast.uct.ac.za/research/ga.htmlThe recession velocities of relatively nearby galaxies show systematic deviations from a uniform expansion field. These deviations are believed to be caused by a gravitational perturbation, in the form of a large - hitherto unnoticed - concentration of mass (5 x 1016 MO) near the southern Milky Way at a redshift-distance of 4350 km/s, named the `Great Attractor' (GA). Attempts to quantify both the nature and extent of the GA have been hampered by the fact that the GA is largely hidden by the disk of the Milky Way. Although there is an excess of optical and IRAS galaxies in this region (Lynden-Bell 1991), no dominant galaxy cluster or other concentration of mass has been identified until recently, when it was found that the Norma cluster (ACO 3627) is a very massive cluster of galaxies located at the heart of the Great Attractor.

Another web page http://www.damtp.cam.ac.uk/user/gr/public/gal_lss.html gives a distance = 45 Mpc, assuming they used the same v, what H0 did they use?

.

3-D map of sphere out to GA

In collaboration with Prof. Kraan-Korteweg (Guanajuato, Mexico), Prof. Fairall and Dr. Woudt (both UCT) have been working on a detailed analysis of the Norma cluster at the core of the Great Attractor. The importance of this cluster was realized following a deep optical galaxy search behind the southern Milky Way. Current studies of the Norma cluster include a detailed dynamical analysis of the cluster, deep R-band imaging of the cluster (MSc project of Mr. Karsten Markus) and a redshift-independent distance determination of the Norma cluster using the near-infrared Fundamental Plane analysis, to unambiguously determine the nature of the Great Attractor.

© Kraan-Korteweg & Lahav, 1998, Scientific American 279, p.50

=>In the direction of the Great Attractor, nothing unusual:

Centaurus

Great Attractor, nothing unusual just an “ordinary” massive cluster:

Norma

“false color”

OK, we can’t “see” the GA with light. So why do we think it’s there??

Gravity!!Concept: measure the distances to a many galaxies as you can in the 1-20 Mpc range and make a plot

What I call a “tadpole” plot

The Tadpole Plot: simplified

The large circles mark a given distance from the sun.

Head is galaxy location, tail length is size of recession velocity ;GA here; as Earth feels tug; so expansion is not seen so great in this dir. .

earth