Transcript ACT+HSC - Princeton

my dream cluster survey
Yen-Ting Lin
Institute for the Physics and Mathematics of the Universe
The University of Tokyo
outline
• fundamental issues in cluster formation and evolution
• an ideal cluster survey
• an IRAC view of cluster galaxy evolution from z=0.4 to z=1.4
fundamental issues
• how did cluster galaxy populations form and evolve?
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luminosity function
morphological mix
star formation history
brightest cluster galaxies (BCGs)
• interactions between galaxies and intracluster medium (ICM)
throughout cluster lifetime?
• measurement of cluster mass (critical for doing sciences with
clusters)
• how to meaningfully compare clusters at different redshifts?
luminosity function
• LF as a function of cluster mass and cluster-centric distance
• redshift evolution
– build up of the faint galaxies on the red sequence
– origin?
• LF of blue galaxies: spectroscopy or/and photometric maximum
likelihood approach
luminosity function
blue galaxy luminosity function?
morphological mix
• fraction of different morphological types as a function of cluster
properties
• redshift evolution
• local processes more important than cluster membership?
• mass-selection vs luminosity-selection of morphology-density
relation
• rise of S0
morphological mix
star formation history
• star formation–density relation evolves with time
– at z~1 SF comments at highest densities
– opposite trend at z~0
– continuous formation of non-SF/early-type galaxies since high-z,
where high-density region leads the process
– leads to an age–density relation at fixed morphology
• Thomas et al (2005) found strong dependence of early-type
ages with environment
• Wolf et al (2007) found an age–density relation for A901/902
• Trager et al (2008) didn’t see it for Coma
• Poggianti et al (2008) didn’t see it in EDisCS
• how is SF shut down? where?
• progenitors of bright and faint S0?
• star formation–density relation
BCG formation
• are BCGs special?
– they are larger, have higher velocity dispersion, larger fraction of
dark matter, higher α/Fe ratio, higher probability to host radio-loud
AGNs, than non-BCGs of same stellar mass, and have different
fundamental plane projections (von der Linden et al 07)
– magnitude gap between BCG and 2nd brightest galaxy larger than
expected than just being the statistical extreme
• mass assembly history
– late time mergers certainly occurred
– are they enough?
: observed Lbcg–Ltot
x: mean “statistical” Lbcg–Ltot
: one simulated Lbcg–Ltot
Lin, Ostriker & Miller (09)
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results based on 494 low-z clusters from the C4 catalog (Miller et al ‘05)
dobs = log[Lbcg,obs]-log[Lbcg,sim]; dsim = log[Lbcg,sim]-log[Lbcg,sim]
overall the observed Lbcg–Ltot relation has 0.8% chance to be statistical (0.03% for BCGs in
high luminosity clusters; 55% for BCGs in low luminosity systems)
BCGs in massive clusters must experience mergers
outstanding issues
• study the evolution of LF, morphology mix, SF, and BCG with
clusters that form an evolutionary track
– more sensible way to compare clusters at different redshifts
– need cluster mass
• LF
– blue galaxy LF
– build up of faint end of red sequence
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what transforms morphology?
what shuts down SF?
better measurement of SFH
better way to compare observed luminosity/stellar mass growth
of BCGs with theoretical models
an ideal cluster survey
• must address fundamental issues in cluster formation and
evolution, in addition to those just mentioned
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spatial distribution of various galaxy populations
AGN content as a function of cluster mass and redshift
effect of cluster merger and substructures in galaxy evolution
merger rate as a function of halo mass and galaxy mass
facilitate comparison of cluster galaxy properties with the field
baryon fraction as a function of cluster mass and redshift
interactions between galaxies/intracluster space stars and ICM
etc
• large area, multiwavelength survey, with large cluster sample
spanning wide range in mass and redshift space
• different detection algorithms (photometric, weak lensing,
spectroscopic, X-ray, Sunyaev-Zeldovich effect), different mass
measurements
an ideal cluster survey
• makes sense to study galaxy evolution using X-ray or SZE
selected clusters, but mass limits may restrict comparisons
using evolutionary tracks
• perhaps more realistic to conduct large scale imaging and
spectroscopic survey (ie a deep version of SDSS), selecting
clusters that follow evolutionary tracks for further follow up
(spectroscopy, UV/near-IR/IR imaging, X-ray, SZE, radio)
• SUMIRE+ACT+eROSITA sounds like great combination!
cluster galaxy evolution
from z=1.4 to z=0.4
collaborators:
Mark Brodwin, Anthony Gonzalez, Adam Stanford
cluster evolution with Spitzer
• studying galaxy evolution within clusters that follow an evolution
sequence
• connecting halos via mass growth history
• IRAC shallow survey (PI: Eisenhardt)
• 9 deg2 Bootes field, with optical data from NDWFS and near-IR
data from NEWFIRM
• good photometric redshift
• detecting clusters with wavelet from density peaks
• ~335 4.5m selected groups/clusters out to z~2
• galaxy number and luminosity (Ltot) in each cluster determined
via statistical background subtraction
• lack of cluster mass info (although with good stellar mass
measurements)
BCGs evolution seen by IRAC
number density
number density
cumulative halo
mass function
mass
Lin
Linetetalal(in
(inprep.)
prep.)
• Deconnecting
halos via mass growth
Lucia & Blaizot (07)
history
• luminosity measured
within 5
cumulative cluster
arcsec aperture (not
optimal…)
luminosity
function
• normalized to the passively
evolving L* from single burst
model
• not much evolution seen: from
3.5L* at z~1.3 to 5.5L* at z~0.5
• much slower X
than the halo mass
X (one)
growth; also slower than
model prediction
• need to find a meaningful way to
luminosity
compare to theoretical
predictions
preliminary!
cluster galaxy population evolution
• calculate mean number of
member galaxies
• look at the change of member
galaxy number from z~1.3 to
z~0.5
• growth in number roughly scales
with mass growth
• BCG growth is slower
preliminary!
Lin et al (in prep.)
conclusion
• some of the fundamental issues in cluster formation and
evolution
• existing cluster samples too small to facilitate faithful
comparison of progenitor-descendent clusters
• deep, wide-field survey absolutely needed to construct large
cluster sample that spans full range in mass and redshift space
• weak lensing seems to be most efficient way to obtain cluster
mass for surveys with Subaru
• spectroscopy absolutely essential to reveal morphological
transform and SFH
• SUMIRE in combination with ACT/eROSITA enables studying
cluster galaxy evolution using (optically) unbiased cluster
sample