1	Astr 5460 Wed., Feb. 12, 2003 Today: WIRO: TBA Reminders/Assignments MAP! Longair, Ch. 3 (Galaxies) Unless noted, all figs and eqs from Longair.
2	MAP! NASA press conference yesterday: Ho=71 T=13.7 Gyr Omega=1.00 Omega_baryon=0.04 Omega_dm=0.23 Omega_lambda=0.73 First stars at z~16 http://map.gsfc.nasa.gov/m_mm.html
3	WIRO – science+ Group Assignment: Take notes and develop a WIRO/PFC Observer’s Handbook. Obviously this is delayed, but it would be a good idea to familiarize yourself with the information on the WIRO webpages: http://physics.uwyo.edu/~mpierce/WIRO/ We will be doing an observing assignment in conjunction with ASTR 5440 involving CMDs of open clusters. Details to come.
4	Reminders/Preliminaries Astro-ph preprints for Friday: http://xxx.lanl.gov/astro-ph SDSS, 2dF Surveys (Darnel)
5	Chapter 3: Galaxies General, basic properties outlined here. More will be covered in ASTR 5440. Classifications Luminosity Functions Galaxy Masses Elliptical Galaxies Spiral Galaxies Correlations with Types
6	Interacting Galaxies: The Antennae
7	Interacting Galaxies: Cartwheel
8	Effects of Collisions Stars pass “through” each other, although orbits disrupted Gas clouds collide Gas stripped away from stars Collisions cause bursts of star formation Ellipticals may be galaxies which have suffered collisions Spirals may be galaxies which have not suffered collisions Joshua Barnes (Hawaii) and the Space Telescope Science Institude provide a simulation of the Antenna Galaxies: http://imgsrc.stsci.edu/op/pubinfo/pr/1997/34/images/anima.mov
9	Simulation of the Cartwheel Encounter From the Space Telescope Science Institute which also provided the Cartwheel image in the textbook: http://imgsrc.hubblesite.org/hu/discoveries/striking_encounters/graphics/cartwheel.mpg
10	Luminosity Functions The frequency with which galaxies of a particular luminosity are found in space. Note that luminosities can be expressed in magnitudes:
11	Luminosity Functions Felton (1977):
12	Luminosity Functions Solid line is the best fit SCHECHTER (1976) function:
13	Luminosity Functions Exact parameters depend on sample. SDSS and 2dF will provide the best estimates soon (Jon?). Typically slopes around a = -1, M_B = -20 (note that quasars by definition more luminous than -23).
14	Luminosity Functions Features to note Morphology matters, also field vs. cluster. M* in rich clusters isn’t a bad “standard candle” cD galaxies in cluster centers are special cases; they are like massive ellipticals but have extra stellar envelopes. They do not fit extrapolations of ellipitical LFs. More on this in Chapter 4. Low luminosity end of LFs not well determined (Irr and dwarf ellipticals). Again SDSS will probably be the best word on this (if it goes faint enough).
15	Luminosity Functions Important number is integrated luminosity per unit volume. Power-law is infinite, but integration is finite. The luminosity density is:
16	Luminosity Density For some typical numbers we get:
17	Luminosity Density So what are observed mass-to-light ratios? Much lower than critical, and now MAP seems to be confirming baryons 4% of critical, consistent with Big Bang Nucleosynthesis (yes, we will get to this stuff!). Dark matter helps, but only up to about 30%. Handy numbers Mean galaxy luminosity is 1.25 L* = 1.55x10¹⁰ h^-2 Lsun Typical number density of 0.01 h^-3 Mpc^-3 indicates a typical galaxy separation of 5 h^-1 Mpc, but of course on those scales galaxies do cluster (Ch. 2)
18	Galaxy Masses On Friday…but an assignment in the meantime (tentatively due Friday Feb 21 – not trivial start early!). Everyone needs to turn in their own paper, but it is OK to share tasks like web searching, downloading, and the like.
19	Galaxy Spectra assignment The textbook is rather weak when it comes to observational properties like spectra – as budding young observers you need to know more! Find and download the galaxy spectra templates of Kinney et al. (1996) – and read the paper! Find and download the spectral synthesis population models of Bruzual and Charlot. “Fit” the elliptical template and one spiral galaxy. Show some plots indicating how broad-band colors change with redshift assuming not evolution (up to z=2). Write up your results like you would for publication with clarity, citations, etc.