gaposchkin 27may04

The Evolution of Galaxies over the Last Half of Cosmic TimebyS. M. Faber and the DEEP & DEIMOS Teams: 

The Evolution of Galaxies over the Last Half of Cosmic Time by S. M. Faber and the DEEP & DEIMOS Teams Supported by CARA, UCO/Lick Observatory, and the National Science Foundation

Hubble Types: two kinds of galaxies : 

Hubble Types: two kinds of galaxies Frei et al., AJ, 111,174, 1996

HST galaxy populations in HDF-N: 

HST galaxy populations in HDF-N z Age There is a major transition at z ~ 1.4. Red galaxies appear to “end” there, and a population of blue irregulars and compacts appears. Driver et al. 1998

Slide4: 

Primordial density ripples are the seeds of galaxies and large-scale structure today Simulation courtesy of Springel, White, and Hernquist

Theory: LCDM cosmology predicts that all galaxies formed at least partly by mergers: 

Z=3 Major progenitor: 3.9 x 1011 M 12 distinct halos (> 2.2 x 1010 M) Z=1 Major progenitor: 1.5 x 1012 6 distinct halos (> 2.2 x 1010 M) Z=0 One aalaxy-sized halo roughly the size of the Milky Way, Mass=2.9 x 1012 M Wechsler et al. 2002 Theory: LCDM cosmology predicts that all galaxies formed at least partly by mergers Within the currently favored cosmology (Lambda Cold Dark Matter, LCDM) structure forms hierarchically, from the bottom-up. Dark matter halos (and possibly the galaxies they host) are built by a series of discrete merging events. Scale Factor Halos Figure courtesy of Risa Wechsler Dark halo merger tree

Local scaling laws relate L, R, v, and Io:A clue to how baryons populate dark halos: 

Local scaling laws relate L, R, v, and Io: A clue to how baryons populate dark halos

Tully Fisher Relation for Spirals: 

Tully Fisher Relation for Spirals The TF relation is the correlation between rotation speed and absolute magnitude for disk galaxies. W is total linewidth, which is close to but not exactly 2 x vrot. Kannappen et al., ApJ, 123, 2358, 2002

Typical disk surface brightness profiles: 

Typical disk surface brightness profiles Courteau, ApJS, 103, 363, 1996 Pure exponentials would be straight lines. The exponential scale length  is a measure of the size of the baryonic disk.

Spheroids follow the r1/4 law: 

Spheroids follow the r1/4 law Again, there is a radial scale length, here usually called Reff, which is the radius that encloses half the light.

Kormendy laws for ellipticals and other dynamically hot systems: 

Kormendy laws for ellipticals and other dynamically hot systems Kormendy, ApJ, 295, 73, 1985 Ellipticals Globular clusters Dw spheroidals

Fundamental Plane for Spheroids: 

Fundamental Plane for Spheroids The Fundamental Plane correlates Re, surface brightness, and  for elliptical galaxies. Fundamental Plane edge on Fundamental Plane face on The Fundamental Plane for Coma and other nearby cluster ellipticals: Jorgensen et al., MN, 280, 167, 1996

A toy evolution model : 

A toy evolution model Fall and Efstathiou 1970, Faber 1982, Blumenthal et al. 1984, Mo, Mao, and Whilte 1998 Assumptions: Each galaxy relates homologously to its DM halo Radius, circular velocity, and mass all scale in proportion to the analogous quantities of the halo at exactly the same epoch (Mo, Mao, White). M/L does not evolve, so that L can be equated with mass. Or…corrections are made based on colors and stellar population theory to derive baryonic mass from light.

Slide13: 

Then the zeropoints of scaling laws evolve as follows: } Changes we are looking for Faber et al., Rome Conference on Disk Galaxies, 2000 Some predictions of the model

The DEEP2 Survey: 

The DEEP2 Survey U.C. Berkeley: M. Davis (PI), A. Coil, M. Cooper, B. Gerke, R. Yan, C. Conroy U.C. Santa Cruz: S. Faber (Co-PI), D. Koo, P. Guhathakurta, D. Phillips, C. Willmer, B. Weiner, R. Schiavon, K. Noeske, A. Metevier, L. Lin, N. Konidaris, G. Graves U. Hawaii: N. Kaiser, G. Luppino LBNL: J. Newman, D. Madgwick U. Pitt.: A. Connolly JPL: P. Eisenhardt Princeton: D. Finkbeiner Keck: G. Wirth K survey (Caltech): K. Bundy, C. Conselice, R. Ellis, P. Eisenhardt Groth Strip: Spitzer MIPS & IRAC, GALEX

DEEP2 basics: 

DEEP2 basics 4 Fields: 14 17 +52 30 (Extended Groth Strip) 16 52 +34 55 (zone of very low extinction) 23 30 +00 00 (on deep SDSS strip) 02 30 +00 00 (on deep SDSS strip) Field dimensions: 30’ by 120’ for fields 2,3,4 15’  120’ for Groth Strip Primary Redshift Range: z=0.75-1.4, pre-selected using BRI photometry to eliminate objects with z<0.75 Magnitude limit: R < 24.1 Grating and Spectra: 1200 l/mm: ~6500-9100 Å [OII] 3727Å doublet visible for 0.7<z<1.4 Resolution: 1.0” slit: FWHM=1.7Å  68 km/s

DEEP2 vs local redshift surveys: 

DEEP2 vs local redshift surveys CFA+SSRS PSCZ LCRS DEEP2 2dF SDSS z~0 z~1

Masks tiled across a 42’x28’ CFHT pointing Standard field is 120’x28’ ~ 1 sq deg: 

Masks tiled across a 42’x28’ CFHT pointing Standard field is 120’x28’ ~ 1 sq deg

DEIMOS during assembly: 

DEIMOS during assembly

DEIMOS on Keck Nasmyth: 

DEIMOS on Keck Nasmyth DEIMOS

Slide21: 

Slit masks are curved to match the focal plane and imaged onto an array of 2k  4k CCDs Readout time for full array (150 MB!) is 56 seconds (8 amplifier mode) DEIMOS Masks and Detector The detector is a mosaic of 8 2K x 4K CCDs from MIT/Lincoln Laboratories. The CCDs are high-resistivity, red-sensitive devices that are 45  thick, with a peak QE of 85% and enhanced QE of 23% at 10,000 A.

Pre-selected photo-z’s > 0.7: 

Pre-selected photo-z’s > 0.7

Typical redshift distribution: 

Typical redshift distribution We are currently measuring redshifts for ~70% of the targets. Nearly all failures are at higher z (Steidel 2003). Photo-z color cut is working very well

The Groth Strip has no color cut: 

The Groth Strip has no color cut The Extended Groth Strip in DEEP2 extends down to z = 0 4,000 galaxies now have redshifts in this field Large scale structure walls are visible Color bimodality: red/blue

Progress on the 1Hour Survey: 

Progress on the 1Hour Survey 90 planned Keck nights in total Started in July 2002 36 nights have been used (40%) 54 nights remain (60%) 5,500 redshifts were measured from 7,000 spectra in the 2002 season (1,600 beyond z = 1) 2,700 redshifts have been processed so far from the 2003 season (all in the Groth Strip) 28,000 spectra have been obtained to date: 40% Planned ending date: Fall 2005

Data beyond z ~ 1 are increasing strongly: 

Data beyond z ~ 1 are increasing strongly Galaxies exist in large numbers beyond z = 1. There is no redshift desert beyond z~1.

Luminosity FunctionsandColor Bimodality: 

Luminosity Functions and Color Bimodality

An important discovery: the red sequence: 

An important discovery: the red sequence Hogg et al., The color-magnitude diagram from SDSS The color-magnitude sequence of early-type galaxies.

COMBO-17: Color bi-modality to z=1.1: 

COMBO-17: Color bi-modality to z=1.1 25,000 galaxies 17-color photo z’s Bell et al. 2004 R-band selected to R = 24

DEEP2 sees the same color bi-modality to z=1.4: 

DEEP2 sees the same color bi-modality to z=1.4 Correcting for M/L, red galaxies are more massive. Willmer et al. 2004 Sloan finds the same red/blue division locally and puts a fuzzy dividing line at 3 x 1010 solar masses.

Slide31: 

Note how the magnitude limit changes slope in the CM diagram with redshift. It is vertical when the color used for restframe absolute magnitude (here the B band) is redshifted into the filter bandpass used for the sample selection (here the R band. Willmer et al. 2004 R-band selection limits the depth of the luminosity function

R-band selection limits the depth of the luminosity function: 

R-band selection limits the depth of the luminosity function Willmer et al. 2004 The limiting absolute magnitude for the “ALL” function at z = 1 is ~ -21.2 B mag.

Luminosity functions: COMBO-17 and DEEP1 agree well to z = 0.8: 

Luminosity functions: COMBO-17 and DEEP1 agree well to z = 0.8 Red dots are COMBO-17, redshifts are photo z’s. Dark squares are DEEP1, redshifts are spectroscopic. Both surveys go to R~24 Curves are COMBO functions at z = 0.0-0.3. Blue galaxies: function shifts to brighter mags. Red galaxies: function shifts down and to left. Restframe B band All Red Blue Willmer et al. 2004 All Red Blue

DEEP2 and COMBO-17 agree out to z = 1.2: 

DEEP2 and COMBO-17 agree out to z = 1.2 Blue galaxies: L* brightens by about 0.8 mag at z ~ 1, but number density is constant. Red galaxies: L* brightens by about 1.6 mag at z ~ 1, but number density is lower. Restframe B band All Red Blue Willmer et al. 2004 All Red Blue Restframe B band

DEEP2 and COMBO-17 agree out to z = 1.2: 

All Red Blue Willmer et al. 2004 All Red Blue Restframe B band DEEP2 and COMBO-17 agree out to z = 1.2 Blue galaxies: L* brightens by about 0.8 mag at z ~ 1, but number density is constant. Red galaxies: L* brightens by about 1.6 mag at z ~ 1, but number density is lower.

CFRS luminosity function evolution: 

CFRS luminosity function evolution Claimed results: Red-galaxy function does not evolve to z ~ 1. DOES NOT AGREE. The blue-galaxy function rises and steepens at the faint end. DATA AGREE, DIFFERENT INTERPRETATION. Mag limit was only R ~ 22.5. New data are 1.5 mag deeper. Steepening Lilly et al. 1995

Luminosity Functions Since z = 1: 

Luminosity Functions Since z = 1 Blue galaxies: Dimming of 0.5-1.0 mag; constant number density Red galaxies: Dimming of 1.7 mag; rising number density with time

Color evolution implies only modest changes in M/L: 

Color evolution implies only modest changes in M/L RC3 DEEP1

Color evolution implies only modest changes in M/L: 

Color evolution implies only modest changes in M/L RC3 DEEP1 0.7 mag 0.4 mag

Blue Galaxy Scaling Laws:Compare to Toy Model: 

Blue Galaxy Scaling Laws: Compare to Toy Model

Toy evolution model (Mo, Mao, and White ’98): 

Toy evolution model (Mo, Mao, and White ’98) Consider a model in which each galaxy relates at all epochs homologously to its DM halo, so that radius, circular velocity, and mass density scale directly with analogous halo quantities. Assume further that M/L does not evolve, so that L can be equated with mass. Then the zeropoints of scaling laws evolve as follows: } Changes we are looking for Faber et al., Rome Conference on Disk Galaxies, 2000

Slide42: 

Stellar Mass vs Size Completeness Map COMBO-17: Disk galaxies Mass-radius relation

Slide43: 

Toy model prediction COMBO-17: Disk galaxies Mass-radius relation No shift in zeropoint vs. time

Slide44: 

The zeropoints of scaling laws evolve as follows: } Changes we are looking for Faber et al., Rome Conference on Disk Galaxies, 2000 The toy model says…

Slide45: 

The zeropoints of scaling laws evolve as follows: } Changes we are looking for Faber et al., Rome Conference on Disk Galaxies, 2000 Now look at the TF relation

Roughly half of one DEEP2 mask: 

Roughly half of one DEEP2 mask Each slitmask has ~140 objects over an 8k x8k array. The average slit length is ~5” with a gap of 0.5” between slits. We tilt slits up to 30 degrees to trace the long axis of a galaxy. OH sky lines

Flexure Compensation CCDs: 

Flexure Compensation CCDs

A fully automated reduction pipeline removes the sky lines : 

A fully automated reduction pipeline removes the sky lines A few percent of one DEEP2 mask, rectified, flat-fielded, CR cleaned, wavelength-rectified, and sky subtracted. Note the resolved [OII] doublets. Shown is a small group of galaxies with velocity dispersion   250 km/s at z1. Note the clean residuals of sky lines. High dispersion improves sky subtraction. SDSS spectral pipeline code by Schlegel et al. allowed us to rapidly develop a full 2d and 1d spectral reduction pipeline that is “completely” automated Thank you, UC Berkeley! [O II] 3727

Poisson-limited sky subtraction : 

Poisson-limited sky subtraction Plot shows residual of flux from b-spline sky model in region of sky emission lines, in units of local RMS. Smooth curve is gaussian, width 1.

High spectral resolution also enables kinematics studies: 

High spectral resolution also enables kinematics studies Improved internal velocity measurements with high-resolution DEIMOS data Resolved [OII] doublet with 220 km/s separation 8 arcsec 8 arcsec

Many rotation curves are marginally resolved spatially: 

Many rotation curves are marginally resolved spatially Four 2-d spectra showing resolved, tilted [OII] emission, and derived circular velocity Vc(r). All curves tend to look linear at low spatial resolution. Cooper et al. 2004

For most of the others, we are able to measure integrated linewidths: 

For most of the others, we are able to measure integrated linewidths Fit lines to 1- D extracted spectrum. Kinematic measurement even when spatially unresolved Weiner et al. 2004 Altogether we measure linewidths for ~80% of all blue galaxies

GOODS-N Keck Treasury TF relation: 

GOODS-N Keck Treasury TF relation Weiner et al. 2004 Keck Treasury Redshift Survey Team Keck and DEEP: DEIMOS spectra, 1420 redshifts in GOODS-N Spectra are now public Zeropoint offset of ~1.5 magnitude at z = 1 Z = 0

DEEP2 TF relation: Season 1: 

DEEP2 TF relation: Season 1 3200 galaxies beyond z = 0.65 Similar results: offset is 1.5-2 mag at z ~ 1 Weiner et al. 2004

Summary: Blue Galaxy Luminosity Evolution: 

Summary: Blue Galaxy Luminosity Evolution - Luminosity function shift: ∆ M ~ 0.5-1 mag - Color change: ∆ M ~ 0.5-1 mag - Number density: Roughly constant - TF zeropoint shift: ∆ M ~ 1.5-2 mag … bigger! Implies that v is SMALLER at fixed mass.

Scorecard for toy model: 

Scorecard for toy model V vs. M change is opposite in sign to that predicted by toy model. Distant galaxies rotate slower than locally at fixed M, not faster. } Changes we are looking for Faber et al., Rome Conference on Disk Galaxies, 2000 R vs. M does not change. Smaller disks at fixed M are expected at high z but are not seen.

Blue-galaxy morphologies: 

Blue-galaxy morphologies Randomly selected blue galaxies in GOODS-North ordered by redshift: z = 0.65 1.4 in z band Redshift

Red-Sequence Galaxies : 

Red-Sequence Galaxies

The red sequence contains a wide range of morphologies: 

The red sequence contains a wide range of morphologies A selection of red-sequence and related galaxies in GOODS-N. Peculiars, spirals, and normal E/S0’s are evident. Harker et al. 2004 Blue center Post-merger Merger Blue ring Normal E/S0 Normal spiral

The red sequence contains a wide range of morphologies: 

The red sequence contains a wide range of morphologies A selection of red-sequence and related galaxies in GOODS-N. Peculiars, spirals, and normal E/S0’s are evident. Harker et al. 2004 Blue center Post-merger Merger Blue ring Normal E/S0 Normal spiral Color maps (blue is dark) Color maps

Three classes dominate: 

Three classes dominate

Same classes seen in GOODS-N: 

Same classes seen in GOODS-N

DRGs populate the valley and increase in numbers at higher redshift: 

DRGs populate the valley and increase in numbers at higher redshift Groth Strip GOODS-N Weiner et al. 2004 ….they may be related to the dusty EROs seen beyond z = 1.5 DRGs are blue squares

Most red-sequence galaxies have large bulges and high concentrations, like normal E/S0’s: 

Most red-sequence galaxies have large bulges and high concentrations, like normal E/S0’s Weiner et al. 2004 Red

But even normal E/S0s are often disturbed : 

But even normal E/S0s are often disturbed Red-sequence E/S0 galaxies in HDF-N. 40% of all spheroidal galaxies to 23 R mag are disturbed. Roughly 1/3 of these show blue centers and are also candidate AGNs. Van Dokkum & Ellis 2003

However, to R=24 at z ~ 0.7, 85% are normal E/S0/Sa’s : 

However, to R=24 at z ~ 0.7, 85% are normal E/S0/Sa’s Normal E/S0s Normal spirals, some edge-on Irregulars and peculiars Bell et al. 2003

Fundamental plane of field spheroidal galaxies to z ~ 1: 

Fundamental plane of field spheroidal galaxies to z ~ 1 SB ~ 2 mag @ z = 1 Open circles are disks with big bulges Gebhardt et al. 2003 2 mag

FP implies 2 mag fading for field E/S0s at z = 1 … if galaxies are not merging and changing their structure: 

FP implies 2 mag fading for field E/S0s at z = 1 … if galaxies are not merging and changing their structure Gebhardt et al. 2003 SB versus redshift from FP: Green are field galaxies from DEEP1 Blue are cluster galaxies from literature X Fading implied by red luminosity function

But…mean integrated U-B colors are close to those of local E/S0s: 

But…mean integrated U-B colors are close to those of local E/S0s

Color vs magnitude evolution for E/S0s: 

Color vs magnitude evolution for E/S0s Gebhardt et al. 2003 U-B is rather flat! Gebhardt et al. see little color evolution despite large surface b’ness evolution. This suggests a “frosting” model in which 94% of the stars formed at z >2 while the remaining 6% continued to form with  = 7 Gyr. Trager et al. (2002) also argue that nearby E/S0s have frosting populations of younger stars.

Stacking improves S/N dramatically. Stacked spectra of 50 red field galaxies at z ~ 0.8 : 

Stacking improves S/N dramatically. Stacked spectra of 50 red field galaxies at z ~ 0.8 <z> = 0.78 Schiavon et al. 2004

Single-burst Balmer ages are only 2-3 Gyr at z ~ 0.85: 

Single-burst Balmer ages are only 2-3 Gyr at z ~ 0.85 Schiavon et al. 2004

A single-burst model to fit the Balmer lines forms as recently as z = 1.35: 

A single-burst model to fit the Balmer lines forms as recently as z = 1.35 Joins red clump at z = 1.1 Forms at z =1.35

But Balmer lines of nearby E-S0s do not fit a single-burst model—nearby lines too strong: 

But Balmer lines of nearby E-S0s do not fit a single-burst model—nearby lines too strong Schiavon et al. 2004 H too strong here Continuing high Balmer strength is more consistent with frosting models …as are constant colors

But Balmer lines of nearby E-S0s do not fit a single-burst model—nearby lines too strong: 

But Balmer lines of nearby E-S0s do not fit a single-burst model—nearby lines too strong Schiavon et al. 2004 H too strong here Frosting models imply ongoing star formation. Is this detected? Continuing high Balmer strength is more consistent with frosting models …as are constant colors

O II 3727 suggests ongoing star formation in 30% of distant red-sequence galaxies : 

O II 3727 suggests ongoing star formation in 30% of distant red-sequence galaxies Konidaris et al. 2004 O II

Slide77: 

OII is below detection limit: When we see OII, the emission is broad: An example of a blue galaxy w/ rotation: Wavelength

Slide78: 

Strong O II Weak O II No O II No clear trend with morphology

Balmer lines increase more rapidly in field E/S0s than in clusters, same as FP offsets: 

Balmer lines increase more rapidly in field E/S0s than in clusters, same as FP offsets Cluster E-S0’s (field)

Current semi-analytic models don’t match the CM diagram: 

Current semi-analytic models don’t match the CM diagram SAM models for z = 0 galaxies, courtesy of Rachel Somerville WE DON’T KNOW HOW TO QUENCH RED GALAXIES Standard Enhanced merging

Current semi-analytic models don’t match the CM diagram: 

Current semi-analytic models don’t match the CM diagram Observed CM diagrams at z = 0.9 and 1.1. WE DON’T KNOW HOW TO QUENCH RED GALAXIES!

The red-galaxy luminosity function is evolving strongly: 

The red-galaxy luminosity function is evolving strongly COMBO-17 & DEEP2 Consistent with jlum = constant! jlum = constant Yet populations are fading by 1-2 mags Stellar mass in red galaxies must at least double since z = 1 (COMBO-17) All Red Blue

Red sequence stellar mass evolution?: 

Red sequence stellar mass evolution? (Bell et al.) U-V color B-band luminosity density U-V colors of COMBO-17 suggest passive fading by at least x3. Fundamental plane suggest fading by x4-6. Yet total luminosity density in red sequence galaxies stays CONSTANT. Total stellar mass in red-sequence galaxies must be rising by x3-6 from z = 1 to now (Bell et al.)

Slide84: 

The “L” model: star formation continues during mass assembly…galaxies grow bright and blue and THEN fade. Bell et al. point out that there are no galaxies in the requisite part of the CM diagram below z = 1, so evolution would have to occur BEFORE z = 1. But then red mass would NOT TRIPLE since z=1. L model Empty ever since z=1! Two extreme models for red-galaxy formation

Slide85: 

The “Z” model: star formation ceases DURING mass assembly. The final stage is then mainly STELLAR mergers. The process must be finely tuned to keep jlum constant. Are there enough mergers after z = 1 to support this? Can we see this happening! Z model Two extreme models for red-galaxy formation

Slide86: 

The “unveiling” model: Red galaxies are heavily obscured before appearing on the red-sequence. Their precursors are not visible in the CM diagram at all. To test: count fraction of faint dusty galaxies vs. z in SIRTF surveys. Z model A third model for red-galaxy formation

Conclusions: 

Conclusions The CM diagram is bimodal to beyond z ~ 1. We should start thinking of red and blue galaxies as two separate classes. Blue galaxies: already well formed by z = 1 and settling thereafter? -- Constant number density, slowly fading stellar populations. -- Small linewidths perhaps because disks not yet settled? -- Does mass continue to accrete? Do radii evolve? Red galaxies: a dynamic population only partly in place by z = 1? -- Rising numbers with time, increasing total stellar mass. -- Evidence of continuing star formation and dynamical disturbances. -- Yet red galaxies are basically gas poor. What quenches red galaxies?

Update on Marc Davis...: 

Update on Marc Davis... Marc suffered a stroke in late June; his recovery and rehabilitation is ongoing, and will continue through much of this year. He is now visiting campus most afternoons, attending team meetings, reading email, etc. His participation increases every week, but the top priority for now remains rehab.

But the volume emissivity of red galaxies stays constant to z ~ 1: 

But the volume emissivity of red galaxies stays constant to z ~ 1 The lines show the fading of PURELY passive stellar populations. If populations fade passively, then mass density of stars in red galaxies must rise by x2 since z=1. COMBO-17; Bell et al. 2003

Passive fading is indicated by high color evolution (reddening): 

Passive fading is indicated by high color evolution (reddening) COMBO-17 sees (U-V) = 0.40 mag since z =1 (restframe).

Bulges of disk galaxies are also very red by z = 1: 

Bulges of disk galaxies are also very red by z = 1 CM diagram for bulge components of disk galaxies: Bulge colors are even redder than the ridgeline of the CM relation for a distant cluster at z = 0.83. Koo et al. 2004

Linewidths as a measure of circular velocity: 

Linewidths as a measure of circular velocity DEEP1 spectra in HST WFPC Groth Strip Vrot measured by Nicole Vogt with full modeling Good correlation between linewidth and Vrot s = 0.6 Vrot predicted (Rix et al. 1997) Weiner et al. 2004

DEEP1 and DEEP2: color vs. redshift: 

DEEP1 and DEEP2: color vs. redshift DEEP1: 600 z’s DEEP2: 5500 z’s --- 10% of total DEEP2 starts at z = 0.75

Luminosity density evolution in COMBO-17: 

Luminosity density evolution in COMBO-17 Restframe B and R increase by only ~1.5; 280 nm increases by x5, indicating more star formation at z ~ 1. Wolf et al. 2003

O II 3727 sample: 

O II 3727 sample SDSS E sample Konidaris et al. 2004

CM diagrams from Sloan: 

CM diagrams from Sloan Blanton et al., ApJ, 594, 186, 2003 Red sequence strongest in g-r Galaxies bluer than this must be bursting CM relation for envelope

Color-color diagrams from Sloan: 

Color-color diagrams from Sloan g-r shows the dichotomy most strongly. Well over half of the local stellar mass is in red galaxies. Why are these relations curved? Not predicted by stellar population models? Emission? Dust? Blanton et al.,

Spectra of red vs. blue Sloan galaxies: 

Spectra of red vs. blue Sloan galaxies Blue Red Kauffmann et al., MN, 341, 33, 2003. Similar results from 2Df (Madgwick et al., MN, 343, 871, 2003). Blue galaxies have young stars (Balmer absorption) and ongoing SFR (emission). Red galaxies have only old stars.

Why We Need to Understand Mergers:The Merger Fraction Increases Rapidly to z~1: 

Why We Need to Understand Mergers: The Merger Fraction Increases Rapidly to z~1 Brinchmann & Ellis (2000) studied galaxy morphologies in the Hubble Deep Field (HDF) and found a distinct rise in the number density of peculiar (read: interacting?) galaxies as a function of redshift. Consistent with Patton et al. (2002) measurement of the merger rate, as measured by close pairs of galaxies, in the CNOC2 survey. Big rise in Peculiars! Slides in the section by Joel Primack and TJ Cox

Theory: LCDM Cosmology predicts that all galaxies formed at least partly by mergers: 

Z=3 Major progenitor: 3.9 x 1011 M 12 distinct halos (> 2.2 x 1010 M) Z=1 Major progenitor: 1.5 x 1012 M 6 distinct halos (> 2.2 x 1010 M) Z=0 1 Galaxy size halo roughly the size of the Milky Way, Mass=2.9 x 1012 M Wechsler et al. 2002 Theory: LCDM Cosmology predicts that all galaxies formed at least partly by mergers Within the currently favored cosmology (Lambda Cold Dark Matter, LCDM) structure forms hierarchically, from the bottom-up. Dark matter halos (and possibly the galaxies they host) are built by a series of discrete merging events. Scale Factor Halos

GALEX: M31, Sb: 

GALEX: M31, Sb

The importance of GALEX: 

The importance of GALEX Cross-calibrate the UV vs. H (optical) SFR indicators Provide key input to dust-absorption models Provide morphological K-corrections for distant galaxies M101, Sc

New work on environment: 

New work on environment SDSS CM diagram Hogg et al. (2003)

Slide105: 

Stellar Mass vs Size Completeness Map

Slide110: 

Toy model prediction

EROs are defined as having R-K > 5: 

EROs are defined as having R-K > 5 They display a wide variety of morphological types. Some fraction are normal E/S0s. Some may be dusty starbursts. ULIRGs? Elliptical progenitors? To count the number of “pure” spheroidal galaxies, we need to weed out and discard dusty/peculiar/reddened EROs. Selection of ERO images from GOODS-S from Moustakas et al. 2003

Slide112: 

Model Spectra Wavelength (Å) Flux (Arbitrary Units/Å) Bruzual & Charlot, 2003 Young Old

Slide113: 

OII is below detection limit: When we see OII, the emission is broad: An example of a blue galaxy w/ rotation: Wavelength Spatial Direction

Slide114: 

Restframe Color (U-B) Red Blue Specific Star Formation Rate SDSS Upper Limit Eisenstein et al, 2003 2 Gyr 6 Gyr 8 Gyr 10 Gyr 4 Gyr 12 Gyr Models: Harker et al, 2004 (in prep) Star formation spread out Most Star Formation Early

Slide115: 

Red Blue Restframe Color (U-B) Excluded Region: born before BB Specific Star Formation Rate

Virtually every ULIRG is found to be a merger or a recent merger remnant: 

Virtually every ULIRG is found to be a merger or a recent merger remnant Borne et al., 2000 95% of all ULIRGS are seen to be double or interacting. Mean separation of nuclei only 2 Kpc. LATE-stage mergers. Bright ULIRGs make stars at a rate of >100 M/yr. Normal galaxies make stars at a rate of ~1 M/yr.

DEIMOS First Light: 

DEIMOS First Light