A cura di Valeria Spagnolo INAF – Osservatorio Astronomico di Palermo
Star formation histories and environment Bianca M. Poggianti INAF – Osservatorio Astronomico di...
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Transcript of Star formation histories and environment Bianca M. Poggianti INAF – Osservatorio Astronomico di...
Star formation histories
and environmentBianca M. Poggianti
INAF – Osservatorio Astronomico di Padova
WE ARE ALL AFTER THE BIG PICTURE:
1) To what extent, environment
To what extent intrinsic/galaxy mass or else
2) 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)
Fra
ctio
n of
gal
axie
s
ESpirals
S0
How to “measure” environment?
One way is to measure the local galaxy density
Number of neighbours, brighter than a certain mag limit, per unit of projected area or volume
Observationally rather easy, even with just photometry –
Another way is to measure the mass of the host structure (cluster and group)
Cluster velocity dispersion
X-ray luminosity
Cluster total luminosity/richness
Weak-lensing
Sunyaev-Zeldovich…
Popesso et al. 2005
Opt
ical
lum
inos
ity
Virial 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 fr
actio
n pe
r de
x
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
Fra
ctio
n of
gal
axie
s
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 fr
actio
n
Local density
Mea
n(E
W)
of O
II g
alax
ies
Local 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-
to-lu
min
ous
rat
io
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 galaxies
EDisCS z = 0.4-0.8 Sloan z = 0.04-0.1F
ract
ion
of m
embe
rs w
ith O
II
with
in R
200
Velocity dispersion10001000 500500
ESO Distant Cluster Survey Poggianti et al. 2006
OUTLIERS!
Evolution of the star-forming fraction
Change 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
SF
R/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 emission
SF 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 fr
acti
on
Post-starburst downsizing in clusters
In 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 etc
Poggianti 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 estimate
Difference 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@[email protected]@[email protected]
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