Star formation historiesand environment

Bianca M. PoggiantiINAF – Osservatorio Astronomico di Padova

WE ARE ALL AFTER THE BIG PICTURE:1) To what extent, environment To what extent intrinsic/galaxy mass or else2) When environment, what physical mechanism

(hence, where & when)

Dressler 1980, as in Dressler et al. 1997

MORPHOLOGY-DENSITY RELATION in clusters

projected surface density (log)

Frac

tion

of g

alax

ies

ESpirals

S0

How to “measure” environment?

One way is to measure the local galaxy densityNumber of neighbours, brighter than a certain mag limit, per unit of projected area or volumeObservationally rather easy, even with just photometry –

Another way is to measure the mass of the host structure (cluster and group)

Cluster velocity dispersionX-ray luminosity Cluster total luminosity/richnessWeak-lensingSunyaev-Zeldovich…

Popesso et al. 2005

Opt

ical

lum

inos

ityVirial mass

X-r

ay lu

min

osity

Limitation of “general field studies” until recently: don’t discriminate “environment” (groups/isolated) – so the evolution “in the field” could be driven by the growth of structure (environment) - now starting (DEEP2, zCOSMOS etc)

Location in a cluster, group, filament, void

In clusters, clustercentric distance (with respect to virial or stripping radius), substructure etc

….usefulness of single, very well studies cases where physics becomes evident

OUTLINE StarFormation and Local Density StarFormation and Cluster/Group Mass Evolution of the StarFormation in Clusters (red sequence, blue/emission line galaxies, post-starburst galaxies) Star Formation and Galaxy Morphology the big picture (?)

IMPORTANT TO ASK TWO SEPARATE QUESTIONS:a) The fraction of star-forming (or passive)

galaxies:Often this is done checking blue vs red fraction: Butcher-Oemler effect ---- red sequence build-up

Quantify the evolution of red% as a function of environment

b) SFR in SFing galaxies depends on environment? If not, either changes are “intrinsic” (NOT-environmentally driven) OR changes are abrupt/fast

The evolution of the star formation-density

relation

Low-z SDSS Baldry et al. 2006

Bundy et al. 2006 DEEP2

+ Simon Lilly’s talk zCOSMOS and posters

Log M (stellar mass)

Mas

s fra

ctio

n pe

r dex

Galaxy stellar mass function itself varies with density

SDSS Baldry et al. 2006, also Kauffmann et al. 2004

Red galaxy fraction depends on both local density and galaxy stellar mass

Low redshift

Local density

Galaxy mass

The red galaxy fraction-density relation at higher-z

DEEP2 Cooper et al. 2007, Gerke et al. 2007

VVDS Cucciati et al. 2006

Galaxies turning from blue to red preferentially in overdense regions (groups??) at z below 1.5 – the establishment of the SFing fraction-density relation at z = 1.5-2 ? (More massive environments, higher-z – clusters are the tail of a distribution…)

0.4<z<0.75 0.75<z<0.85 0.85<z<1.0 1.0<z<1.3

Low redshift

Halpha equivalent width

Frac

tion

of g

alax

ies

Balogh et al. 2004a

So, the SF-ing % depends on density. The SF in SF-ing galaxies doesn’t ?

COSMOS Cassata et al. 2007 – also Noeske’s 2007 Letters

WHAT CHANGES WITH ENVIROMENT IS ONLY THE STARFORMING FRACTION (higher-z)?

Color-mass diagram, at different local densities

Z~ 0.7

Black z=0.4-0.8 (ESO Distant Cluster Survey)

Red z=0.04-0.08 (SDSS clusters) Poggianti et al. 2008

Sta

r-fo

rmin

g fra

ctio

n

Local densityM

ean(

EW

) of O

II ga

laxi

esLocal density

STAR FORMATION-LOCAL DENSITY RELATION

Clusters at z=0 & 0.4-0.8

?

Average SFR per galaxy vs density: field at z=1

Elbaz et al. 2007Cooper et al. 2008

The relation between the average star formation rate per galaxy and the local density is reversed compared to the local Universe . (is it?)

Z=0

Z=1Z=1

And for just star-forming galaxies? With same mass distributions?

higher density

ESO Distant Cluster Survey Poggianti et al. 2008

All galaxies (black) SFing galaxies (blue)

Clusters + groups at z~0.4-0.8

Average SFR vs density (sSFR same way)

Seems to imply the SFR in SF-ing galaxies depends on density – while

the EW-density relation seems to imply it doesn’t

The evolution of the star formation activity

as a function of cluster/group mass

The oldest galaxies at any redshift Color-Magnitude sequence: zero-point, slope and scatter consistent with passive evolution of stellar populations formed at z>2-3 (Bower, Ellis, Kodama…).

Fundamental plane, mass-to-light ratios and Mg-sigma relation, bright-end of K-band (mass) luminosity function

ACS team Z=0.8-1.3 Mei et al. 2008

STAR FORMATION DOWNSIZING: the cluster view

0.0 redshift 1Red

seq

uenc

e fa

int-t

o-lu

min

ous

ratio

De Lucia et al. 2004, 2007, Kodama et al. 2004, Stott et al. 2007, Tanaka et al. 2005, but Andreon 2008

A deficiency of red galaxies at faint magnitudes in distant clusters compared to nearby clusters.Most massive galaxies are the first ones to conclude their SF activity - The more massive, the older their stellar populations,and the higher the redshift of their last SF

V absolute magnitude

U-V

col

or

Kodama’s talk

STAR FORMING FRACTION vs z IN CLUSTERS

Spectroscopy confirmed a widespread SF activity in z=0.4-0.5 clusters:

Star-forming fraction 30-50%, compared to nearby similar clusters that contain few galaxies with ongoing or recent SF

Fraction of blue galaxies versus redshift

Butcher-Oemler 1984, Kodama & Bower 2001

Dressler & Gunn 1982, 1983, Couch & Sharples 1987, Poggianti et al. 1999, Dressler et al. 1999, Ellingson et al. 2001, Balogh et al. 1997….

0.0 z 0.5

Trends with cluster/group mass: low-zRicher, more centrally concentrated, relaxed clusters have fewer star-forming/late-type galaxies. Early attempts with (e.g. Zabludoff & Mulchaey 1998, Biviano et al. 1997) and without (e.g. Smail et al. 1998, Andreon & Ettori 1999) success. But hard to quantify:

Fractions of galaxy types versus system mass (vel.dispersion)

Weinmann et al. 2006

12 15 log M

Balogh et al. 2004

Red galaxy % vs sigma

Goto 2005 – also Tanaka et al. 2004

Blue galaxy % vs sigma

Trends with system mass at low-z II

Evolution of the % of SF-ing galaxiesEDisCS z = 0.4-0.8 Sloan z = 0.04-0.1Fr

actio

n of

mem

bers

with

OII

with

in R

200

Velocity dispersion10001000 500500

ESO Distant Cluster Survey Poggianti et al. 2006

OUTLIERS!

Evolution of the star-forming fractionChange in star-forming fraction between 20 and 50% - stronger in lower mass systems

How are these trends established? Note that the low-z trend HAD break at some sigma, otherwise the field today would be like the clusters/groups.

A universal 3 X 10^12 halo mass threshold for quenching (within 3Gyr from infall) produces far too few starforming galaxies in clusters of any sigma today! Poggianti et al. 2006

How do galaxies turn from star-forming to passive in clusters, and why: well studied, individual clusters

Evidence for enhancementslow declinesudden truncation

Moran et al. 2005, 2006, 2007a,b,c

Small bursts at virial radius

Slow conversion of spirals to S0s in infalling groups in the outskirts (gentle gal.-gal. Interactions?) + additional fast truncation mechanism in inner regions (ram pressure? where ICM dense)

Harassment, ram pressure and starvation?

Cl0024 and MS0451 at z=0.4

starvation truncation

A quenching timescale dependent on galaxy mass…

STAGES Wolf et al. 2009

Also Haines et al. 2006, 2007

Dusty red galaxies: logM=[10-11], low mean specific star formation rate (dust reddened), indicating quenching is slow – (see also Goto et al. 2003) – but could it be just that are more massive are earlier-type galaxies?

In lower mass galaxies, fast quenching accompanied by morphological change (no cluster-specific red spirals phenomenon at logM<10)

logMass

Log

SFR

/M

If a truncation mechanism acts fast, it leaves a clear

signature…. post-starburst galaxies

POST-STARBURST SPECTRA IN DISTANT CLUSTERS (z=0.4-0.5)

post-starburst galaxies 25% of the distant cluster galaxy population Dressler & Gunn 1983, Couch & Sharples 1987, Dressler et al. 1999, Poggianti et al. 1999, Tran et al. 2001,

2004

Larger % in clusters than in field at similar z’s (Dressler et al. 1999, Poggianti et al. 1999, Tran et al. 2003,2004, now Ediscs, Ma et al… – but Balogh et al. 1999)

SF truncation in clusters

strong Balmer absorption and no line detected in emissionSF ended abruptly sometime during the last Gyr

EDisCS Poggianti et al. 2009

At z=0.4-0.8, post-starburst galaxies more frequent in more massive clusters and in some of

the groups…

…those groups with a low OII fraction for their sigma

K+a

frac

tion

Post-starburst downsizing in clustersIn the Coma cluster – Rare among bright galaxies, but common (15%) among dwarfs (Poggianti et al. 2004) Evidence for ICM origin:In Coma, associated with X-ray substructure, pointing to impact with ICM shock fronts (Poggianti et al. 2004).In cluster at z=0.5, post-starbursts within the (projected) ram pressure stripping radius (Ma et al. 2008)

Mv ≥ - 18

Post-starburst fractions among bright “field” galaxies

In the field at z=0, mostly associated with mergers (Zabludoff et al. 1996, Yang et al. 2004, 2008, Goto 2005, Nolan et al. 2007). Confirmed by spectroscopy of companions (Goto 2005, Yamauchi et al. 2008, also Goto et al. 2008)

Highly probable different origin in different environments

Rare at all redshifts (Zabludoff et al. 1996, Goto 2005, Yan et al. 2009)

AGN and SN feedback above/below 10^10 Msun – descendants of LIRGs and ULIRGs (Kaviraj et al. 07)Evolution of frequency also in the field: a factor of 230 between 0.07 and 0.7 (Wild et al. 2009)

How relevant for the evolution of the star-forming fraction and of the cosmic SF history? Open question (eg Yan et al. 2009 vs Wild et al. 2009 – 40% of red sequence growth rate)

GROUP “BIMODALITY” ? THE KEY?Evidence: some groups look like “mini-clusters”, some look like field (at the same mass) for their star forming fraction, morphologies, post-starburst incidence etcPoggianti et al. 2006, 2008, 2009a, Wilman et al. 2005, 2009, Kautsch et al. 2008, Jeltema et al. 2007 – also Zabludoff & Mulchaey 1998….Not simply “true” vs “false” groups? (eg. X-ray groups Jeltema et al. 2007 Rasmussen’s talk) – hard to explain as wrong mass estimateDifference between two types of groups ought to help to understand what is going on at the group level

Fritz et al. In prep.

Red sequence build-up from “secular” SF histories

Irr

Sd

Sc

Sb

Sa

S0

E

Log stellar mass (Msun)

Star formation and galaxy morphology

(Hubble type)

Desai et al. (2007)

(Dressler et al. 1997, Fasano et al. 2000, Postman et al. 2005, Smith et al. 2005 – but also Andreon et al. 1998, Holden et al. 2009)

MORPHOLOGICAL EVOLUTION IN CLUSTERS: from spiral to S0 GALAXIES

Elliptical % S0 %

Spiral+Irr %

Wide-field Nearby Galaxy-cluster Survey (WINGS) Poggianti et al. 2009 ApJ Letter

Evolution of the morphological fractions

AGAIN, EVOLUTION IS STRONGER IN LESS MASSIVE CLUSTERS!! also Wilman’s talk, Kautsch et al. 2008 for

S0s in groups (and Dressler 1980…)

Also Dennis Just’s poster

WINGSWINGSdatabasedatabase

Wide Field (35’, R500 in all)Wide Field (35’, R500 in all)Sample:Sample: 76 76 clusters, complete in L clusters, complete in LXX; ; 0.04<z<0.070.04<z<0.07

Optical Imaging (BV;Optical Imaging (BV;WINGS-OPTWINGS-OPT))WFC@INT+WFI@ESO2.2WFC@INT+WFI@ESO2.2

Fiber Spectroscopy (Fiber Spectroscopy (WINGS-SPEWINGS-SPE); ); 4848 clustersclustersWYFFOS@WHT+2dF@AATWYFFOS@WHT+2dF@AAT

NIR NIR ImagingImaging (JK; (JK; WINGS-NIRWINGS-NIR); ); 2828 clusters clustersWFCAM@UKIRTWFCAM@UKIRT

WINGSWINGSdatabasedatabase

Astro Pizza - Padova 4 Feb. 2009Astro Pizza - Padova 4 Feb. 2009

Follow-Follow-upup

imagingimaging

** U-band; U-band; 1818 clusters WFC@INT+90’@Bok+LBC@LBT (almost clusters WFC@INT+90’@Bok+LBC@LBT (almost completed)completed)* * HHnarrow-band few clusters so far WFC@INT (ongoing)narrow-band few clusters so far WFC@INT (ongoing)** BV, Very Wide-Field ~ BV, Very Wide-Field ~50 50 clusters; OmegaCam@VST (planned)clusters; OmegaCam@VST (planned)

AD HOCAD HOCSoftwarSoftwar

ee

* * GASPHOTGASPHOT automated automated surface surface photometryphotometry

* * MORPHOTMORPHOT automated automated morphological morphological classificationclassification

* * SIMSPEC SIMSPEC SFHs and SFHs and stellar massesstellar masses

Wings Catalogs Wings Catalogs

Optical photometry (Fasano et al. 2006, Varela et al. 2009 in press)

Near-IR catalogs release (Valentinuzzi et al. 2009 in press)

Spectroscopic catalog release (Cava et al. 2009 in press)

Line measurements and star formation histories (Fritz et al. 2009a in prep., 2009b in prep.)

Morphology and sur. phot. catalogs(Fasano et al. 2009, in prep., D’Onofrio et al. in prep.)

Lick Indices Release(Hansson et al. 2009 in prep.)

UV catalogs release(Omizzolo et al. 2009, in prep.)

FORMULATING A WORKING HYPOTHESIS

What if what really matters is the primordial matter density (“primordial environment”, if you like) AND the primordial “available mass”That correlates with the distributions of local projected future density global environment galaxy mass + additional mechanisms on some galaxies required (eg. post-starbursts) – is there ANY evidence that a group-specific mechanism (=strangulation) is needed??How different from “common” picture?

FROM BLUE TO RED ON A COSMIC SCALE: either it happens in groups, or it is “intrinsic” – but it cannot happen in all groups, as testified by the large scatter in galaxy properties in groups – so, hard to be explained by strangulation