Multivariate Properties of Galaxies at Low Redshift

Galaxy Properties from Imaging Luminosity functions Luminosity functions Star formation rate Star formation rate Stellar mass Stellar mass Morphology Morphology Color-magnitude relation Color-magnitude relation Environment Environment Photometric redshift Photometric redshift 2-D Clustering 2-D Clustering 2 6-color SDSS scans of 2.5°x2.5°.

Galaxy Properties from Spectroscopy Detailed star formation history Detailed star formation history Dynamical mass Dynamical mass Metallicity Metallicity Dust content Dust content 3-D clustering 3-D clustering AGN activity AGN activity

Galaxy Surveys: Optical & NIR DEEP2 AEGIS MS1054 COMBO17 MUSYC Steidel ELAIS-S1 From Mara Salvato’s web page

Where is the stellar mass? Galaxies at ~ M  contain most of stellar mass. Galaxies at ~ M  contain most of stellar mass. SFR and D n show bimodality. SFR and D n show bimodality. Some, not much, environmental dependence Some, not much, environmental dependence Kauffmann et al. 2004

Bivariate LF’s: Morphology Sersic index n: Sersic index n: n=4: elliptical n=4: elliptical n=1: spiral n=1: spiral Ellipticals dominate bright end; later types at faint end. Ellipticals dominate bright end; later types at faint end. Faint end slope varies with n; Bright end truncation invariant. Faint end slope varies with n; Bright end truncation invariant. SB trends similar; high SB’s have higher n. SB trends similar; high SB’s have higher n. Ball et al 2005

Bivariate LF’s: Color u-r measures (roughly) ratio of current to past star formation. u-r measures (roughly) ratio of current to past star formation. Red galaxies dominate at bright end. Red galaxies dominate at bright end. Blue galaxies have steeper faint-end slope. Blue galaxies have steeper faint-end slope. r-z distribution shows less trend, because fewer blue galaxies. r-z distribution shows less trend, because fewer blue galaxies. Ball et al 2005

LF’s in Field vs. Clusters Field R-band LF (SDSS) well-fit by Schechter function, with  ~ Field R-band LF (SDSS) well-fit by Schechter function, with  ~ Clusters show an excess population of small galaxies. Clusters show an excess population of small galaxies. GALEX data shows faint-end upturn is from passive dwarfs. GALEX data shows faint-end upturn is from passive dwarfs. Trentham et al 2005 Cortese et al. 2005

Stellar Mass Fcn in Field vs. Clusters Near-IR (J, K) allow more direct tracer of M *. Near-IR (J, K) allow more direct tracer of M *. Clusters show steeper faint end, field is shallow. Clusters show steeper faint end, field is shallow. Non-emission line field galaxies show very shallow slope. Non-emission line field galaxies show very shallow slope. Balogh et al 2001

Morphology-Density Relation Ellipticals prefer denser environments. Ellipticals prefer denser environments. Discovered in the 80’s, regarded as a fundamental aspect of environment. Discovered in the 80’s, regarded as a fundamental aspect of environment. Why does it occur? Why does it occur? Ram-pressure stripping? Ram-pressure stripping? Merging? Merging? Harassment? Harassment? Starvation? Starvation? Goto et al. 2004

It’s star formation history, stupid! At fixed luminosity and color, there is no strong relationship between density and either Sersic index or surface brightness. At fixed luminosity and color, there is no strong relationship between density and either Sersic index or surface brightness. It’s not morphology- density, it’s color- density, or perhaps star formation history-density relation. Blanton et al. 2005

Color, magnitude, morphology Ellipticals (high- n) tend to be red and high-SB. Ellipticals (high- n) tend to be red and high-SB. CMD shows bimodality: “red sequence” & “blue cloud”. CMD shows bimodality: “red sequence” & “blue cloud”. Color-SB relation shows similar bimodality. Color-SB relation shows similar bimodality.

Red sequence evolution Red sequence in place at z~1 (10 Gyr ago). Red sequence in place at z~1 (10 Gyr ago). Gets slowly redder with time; z f ~2+. Gets slowly redder with time; z f ~2+. Dominated by early-types (not dusty spirals). Dominated by early-types (not dusty spirals).

Mass-Metallicity Relation SDSS emission line galaxies, central regions. SDSS emission line galaxies, central regions. M * -Z shows a strong trend up to M * ~ M , then flattens to higher M *. M * -Z shows a strong trend up to M * ~ M , then flattens to higher M *. Scatter is small: 0.2 dex at low-M, 0.07 dex at high-M. Scatter is small: 0.2 dex at low-M, 0.07 dex at high-M. Origin yet unclear, but outflows likely needed. Origin yet unclear, but outflows likely needed. Tremonti et al Lee et al. 2006

Tully-Fisher and M * /L Stellar/baryonic mass vs. dynamical mass. Stellar/baryonic mass vs. dynamical mass. ~x7 M * /L variation in B, ~x2 in K (for spirals). Tightest with B-R color. ~x7 M * /L variation in B, ~x2 in K (for spirals). Tightest with B-R color. With M * /L(color), TF has M *  v 4.5. With M * /L(color), TF has M *  v 4.5. With HI data, baryonic TF M b  v 3.5±0.2. With HI data, baryonic TF M b  v 3.5±0.2. Extending to lower masses suggests M b  v 4 : variation with M b ? Extending to lower masses suggests M b  v 4 : variation with M b ? Recall M halo  v 3, so at face value small halos have less baryons: M b /M h  v 0.5. Recall M halo  v 3, so at face value small halos have less baryons: M b /M h  v 0.5. Lv3Lv3 Lv4Lv4 Bell & de Jong 2001 McGaugh 2004

AGNs: Where do they live? In M*>10 10 M . In M*>10 10 M . Morphologically similar to early- types. Morphologically similar to early- types. OTOH, recent SF similar to late- types (esp. in strong AGN). OTOH, recent SF similar to late- types (esp. in strong AGN). Kauffmann et al 2003

AGNs and galaxy evolution AGNs roughly occupy “green valley”. AGNs roughly occupy “green valley”. Black hole growth occuring in M * ~ M  galaxies. Black hole growth occuring in M * ~ M  galaxies. Same M * as transition in colors, SFRs, etc. Same M * as transition in colors, SFRs, etc. Cause or effect? Cause or effect? Kauffmann et al 2004

Clustering: 2PCF  =(r/r 0 ) - ,  ~1.8 and r 0 ~5 Mpc/h.  =(r/r 0 ) - ,  ~1.8 and r 0 ~5 Mpc/h. Departs significantly from pure power law. Departs significantly from pure power law. Red galaxies have steeper x slope. Red galaxies have steeper x slope. Mild luminosity dependence, strongest at luminous end. Mild luminosity dependence, strongest at luminous end. Zehavi et al. 2003, 2004 Norberg et al 2001

Halo Occupation Distribution HOD = P(N g,M h ). HOD = P(N g,M h ). Made up of “1-halo” and “2-halo” terms. Made up of “1-halo” and “2-halo” terms. From this, get bias: b ≡(  gg /  mm ) 1/2. From this, get bias: b ≡(  gg /  mm ) 1/2. has character- istic shape; can derive by matching  (r). has character- istic shape; can derive by matching  (r). Yang et al 2004 Zehavi et al 2003

Conditional Luminosity Function  (L|M)dL: Luminosity fcn in bins of halo mass.  (L|M)dL: Luminosity fcn in bins of halo mass. Tune  (L|M) to reproduce LF,  (L), and T-F. Tune  (L|M) to reproduce LF,  (L), and T-F. Depends on cosmology, or anything that affects halo abundance. Depends on cosmology, or anything that affects halo abundance. Yang et al 2003