Transcript Piero Rosati -- Old galaxies at z=1-1.4

Piero Rosati -- Old galaxies at z=1-1.4
RDCS1252 (z = 1.24) C-M Relation with HST/ACS and VLT/ISAAC
(Blakeslee et al. 03; Lidman et al. 03; Rosati et al . 04)
Lidman et al. 2004
VLT/ISAAC
HST/ACS
Kodama&Arimoto 97 models
ZF= 2,3,5
E
S0
Late
The scatter and slope of the red sequence is very similar to low-z
clusters, basically frozen over 65% of look-back times !
The suburbs of
A851: 7/9 are
starbursts!
only 2 k-type Alan Dressler -and no e(c)’s! Starburst galaxies
and cluster suburbs
6 are e(a),
...a remarkable change in the amount and
1 k+a
character of star formation in the
recent past.
In rich clusters of galaxies, but even in
“the field,” the mode of star formation
appears to shift to a much greater
fraction which are starbursts (20-30%)
Hypothesis: As gas-rich disk
galaxies fall into these rich
clusters, either individually or
in small groups, they are
severely jostled by tidal
interactions. Alternate
hypothesis: shocks from
intracluster medium drive the
starbursts.
Dressler et al. 2004
Tommaso Treu:
E+S0s: cluster induced bursts.
GALEX view
• Abundance of NUV
detected E/S0
consistent with
moderate amounts of
recent star formation
10^7-10^8 Gyrs
inside the virial
radius.
• Consistent with infall
scenario and burst of
starformation at ~ the
virial radius
CL0024
Moran et al. 2006
Also Adam Muzzin; Spitzer starbursts
Christian Wolf -- A population of dusty red galaxies
2-D Family: Age x Extinction
Michael Balogh -- Color trends at low-z
• Fraction of red galaxies
depends strongly on density.
This is the primary influence of
environment on the colour
distribution.
• Mean colours depend weakly on
environment: transitions
between two populations must
be rapid (or rare at the present
day)
• Trend is not completely absent
for fainter galaxies; but never
dominant
•Simple dependence of “late-type” fraction on environment characterizes much of
observed trends (e.g. SFR-density, morphology-density, colour-density etc.).
•Interpretation?
1.Two modes of formation. Within each peak is variance due to dust,
metallicity (second-order effects).
2.Transitions: Where do S0, E+A fit in?
Balogh et al. 2004
Anja von der Linden -- Local cluster samples from
Sloan
Andrea Biviano -- Galaxy orbits
Paola Popesso -- The LF at low-z
When measured within the physical size of the systems (given by r200),
the Cluster LF is universal (Popesso et al. 2005)
•bimodal behaviour of the cluster LF (steepening at the faint end)
•the cluster LF is universal when measured with the virial radius
•DGR increasing with the clustercentric distance
Vincent Eke -- 2PIGG LF vs mock catalogues from SA
The way to do it! …but models don’t get it right
Veronica Strazzullo -- The LF at 1.1 < z < 1.3
--- The evolution of the NIR luminosity function of bright
galaxies in X-ray luminous clusters at z~1.2 is consistent with
passive evolution
--- The redshift evolution of K* up to z=1.2 is compatible
with passive evolution of a stellar population formed at z>2
--- The bright end of the LF appears to be dominated by
galaxies already evolved both morphologically and
spectrophotometrically
Also Gabriella
De Lucia, LF of
red galaxies at
z=0.8
Kim –V. Tran -- Red
merging pairs
also Marc Postman other
high-z clusters: not
universal phenomenon, but
MS1054 not unique
Anthony Gonzales -- Supergroup (or supercluster?)
•
•
Detection:
– Las Campanas Distant Cluster Survey
(Gonzalez et al. 2001)
– 4 candidates at z~0.4 within
a 7’ diameter region
Confirmation:
– Chandra + spectroscopy
– 6 extended sources within a 13’
diameter region (~4 Mpc)
Groups at z=0.37 (2,3,4,5)
Cluster at z=0.48 (1)
No redshift yet (6)
•
“Supergroup” SG1120-1202
Hierarchical Assembly: SG1120
Ongoing mergers of massive galaxies
Morphology - Density Relation
PG84 z~0 E+S0 Fraction
D80/D97 z~0 E+S0
P2005 ACS z~1 E+S0
Smith et al2005 z~1 E+S0
P2005 ACS z ~ 1
Ellipticals
PG84 z ~ 0 Ellipticals
D80/D97 z ~ 0 Ellipticals
P2005 ACS z ~ 1 S0 Fraction
PG84 z ~ 0 S0 Fraction
D80/D97 z ~ 0 S0 Fraction
Projected Density
Marc Postman - Morphologies
•Cluster spirals are
significantly redder their
field counterparts
•But, their quantitative
morphologies (C,A,S) are
indistinguishable
•Sizes (R1/2 or disk scale
height) of cluster and
field galaxies are similar
•Blue cluster disk galaxies
show evidence (97% C.L.)
for “centralized” star
formation.
Bianca Poggianti -- Evolution of the % of
starforming galaxies as a function of environment
EDisCS: z = 0.4-0.8
Sloan (Abell): z = 0.04-0.1
Direct link between the star formation activity in galaxies and the history of
growth of clusters and groups?
In a scenario in which the passive galaxy population has two components
(primordial and quenched galaxies), only two informations needed:
 fraction of mass/galaxies already in groups at z=2.5
 fraction of mass/galaxies that have experienced the cluster environment
for a few Gyr
Current scenario (common to all of us?)
•
In clusters, some galaxies are very old (most massive, Es), both in SF and
assembly. A significant % of the cluster galaxies have stopped forming stars at
z<1 (from spirals to S0s)
•
Morphological evolution and evolution in the SF activity are taking place
•
Massive galaxies have on average shorter SF timescales than smaller ones
(downsizing)
•
Dense environments quench star formation (dense environments?)
•
Environmental conditions act in two ways – New concept of “nature” vs
“nurture”: “Today’s population is the result of different environments at
different epochs”. “Primordial” environment & “proper” environmental
effects (when galaxy experiences a “new” environment for the first time) –
“Proper environmental effects” are second order effects?
•
Starbursts a more common mode of SF in the past than today
•
Well sinked in all of us:
clusters as part of a “web” – necessity of “cross-environmental” studies (widefield studies, importance of the group environment)
history of the “environment” and galaxy history probably closely related
1.
Results to be reconciled:
established scenario for Es and S0s form. & evolution
occurrence, consequences & timing of mergers
transformations of galaxy properties and variegated SFHs
apparent “simplicity” of color bimodality
dependence of SF properties on environment at high-z
no apparent dependence at low-z?
starbursts a more common mode of SF at higher z in all envrs.
environmentally-related enhancement of SF?
2.
We still don’t know how the “proper” environmental effects really work to
quench and/or enhance SF
3.
To what extent are we observing “intrinsic” (field) galaxy evolution, and to
what extent are field studies looking at environmentally-driven evolution?