Galaxy evolution with Euclid
Jarle Brinchmann
Leiden
Outline
• What Euclid will provide us with.
• Galaxy formation science with Euclid
• Very large samples → distribution functions
• Exquisite imaging → morphological studies, mergers, strong
galaxy-scale lenses, ..
• Weak lensing → Galaxy evolution as a function of halo
properties, galaxy alignment, ...
• Very large volume → Rare sources, probing the extremes
• Spectroscopy → Metals, star formation @ z>1
• Why Euclid only provides part of the picture.
The SDSS lesson
Out of 834 “official” SDSS journal papers:
Area
# papers
Percentage
Cosmology
93
11.2%
Supernovae
62
7.4%
Legacy
679
81.4%
11%
7%
81%
Two lessons:
Offical
SDSS
• Most papers might come from areas
outside the core science of the project.
• A good survey causes the community
to produce a lot of papers independent
of the consortium.
16%
84%
Euclid compared to ground-based surveys
NIR imaging depth is similar to
the deepest images from the
ground.
Euclid Wide (YJH)
4
Log Area [deg2]
VIKING (YJHK)
2
Euclid Deep (YJH)
VIDEO (YJHK)
0
Ultra-VISTA (YJHK)
-2
22
24
26
AB limiting magnitude [5 sigma]
28
VISTA
SASIR
Euclid
Wide survey
680 years
66 years
5 years
Deep survey
72 years
7 years
“5 years”
Euclid compared to ground-based surveys
Courtesy: M. Cropper
Euclid Wide (YJH)
4
Log Area [deg2]
VIKING (YJHK)
2
Euclid Deep (YJH)
VIDEO (YJHK)
0
Ultra-VISTA (YJHK)
-2
22
24
26
AB limiting magnitude [5 sigma]
28
And visible imaging will be revolutionary.
Euclid compared to ground-based surveys
Based on a compilation by I. Baldry
105
3D-HST WISP
K20
TKRS
DEEP
Density of spectra [#/deg2]
10
illi
on
VVDS-deep
FDF
4
1m
zCOSMOS-bright
DEEP2
sp
ec
GDDS
VVDS-ud ZCOSMOS-deep
CFRS
VIPERS
2
Shim09
LBG-z3
AGES
CNOC
MUNICS
VVDS-wide
tra
MOONS
Euclid
GAMA
3
10
KPGRS
102
MGC
Autofib
WiggleZ
BOSS
ESP
2dFGRS
H-AAO
1,0
00
SDSS-DR9
LCRS
sp
e
ct
101
0
10
10-1
10-2
ra
6dFGS
UV
B
R
I
NIR
IR
Em
AARS
DURS
2MRS
SSRS2 CFA2
UCM
PSCz
SAPM
CfA
10-1
100
101
102
Area [deg2]
103
104
105
The leap in high resolution imaging
Unique area imaged by HST since 1997 at |l| > 30º
Area imaged [deg 2]
10
All
8
6
2
C
P
WF
4
ACS
3
C
F
2
W
2000
2005
Year
2010
The leap in high resolution imaging
The leap in high resolution imaging
The leap in high resolution imaging
Euclid
Area imaged [deg2]
10000
1000
100
10
HST
1
2000
2005
2010
Year
2015
2020
2025
Galaxy & AGN Evolution
105
Today we lack
spectroscopic
studies of
galaxies at a
crucial time of
the Universe
VVDS/DEEP-2/Steidel et al/FDF/Wiggle-Z/zCOSMOS++
z=0.1
103
# per
104
102
101
SFR
[Msun/yr/Mpc3]
Spectroscopically observed galaxies
Hopkins & Beacom (2006)
0.20
0.15
0.10
0.05
0.00
Star formation history of the Universe
0
1
2
Redshift
3
4
Galaxy & AGN Evolution
4 10 6
Euclid wide
de
Ha out
si
2 10 6
# per
z=0.1
3 10 6
1 10 6
x10
0
1
Ha outsid
e
2
Redshift
3
4
This will change with Euclid (and MOONS ++). Many/most of these
sources be detected with SKA1 depending on integration time.
Interesting: Different time-scales, different AGN sensitivity,
different dust sensitivity - complementary view.
Euclid will also do (some) resolved spectroscopy
Nelson et al (2012)
Example from 3D-HST survey. With Euclid we can do
the same reconstruction for high EW(Ha) galaxies.
Resolution ~0.3” - good match to SKA.
Euclid will also do (some) resolved spectroscopy
Nelson et al (2012)
Can then compare size of the star-forming disk to the
stellar disk (from the optical imaging) +++
• Multi-dimensional distributions of physical parameters.
• The growth and evolution of quiescent high-z galaxies.
• Galaxy evolution as a function of environment.
• Galaxy evolution at fixed halo mass.
• Baryon to star conversion efficiency as a function of
physical properties of halos and galaxies.
• Detailed properties of galaxy halos from large samples
of strongly lensed galaxies.
• Intrinsic alignments and galaxy properties.
• Galaxy merger evolution.
• QSOs at z>8.
• Type II AGN, their evolution and relationship to dark
matter halos and galaxy properties
Rare
Spectra
Images
WL
Large
(Some) Science cases for galaxy
evolution with Euclid
The high-redshift Universe
Euclid the discoverer
z > 8 AGNs with Euclid
Are there QSOs at z>8-9?
Euclid should be able to get
spectra of the brightest with
follow-up from the ground.
Clear synergy with SKA see e.g. talk by Mellema & if
has radio emission.
Roche et al (2011)
High-z LBGs with Euclid
• From the Deep Survey
• Probing the bright end of the LF at high z
• Selection with Euclid-only data:
• J < [25.5-26] at [8-5] σ
• [700-4000] galaxies at z =7 ± 0.5
• [150-1000] galaxies at z = 8 ± 0.5
• Deep z band data (AB = 27, 5σ) highly
desirable for discriminating z = 7 galaxies from
T-dwarfs.
• Spectroscopy: Lyα emission of ~ 100 objects
from the photometrically selected sample
• Strong need for follow-up observations, e.g.
• Faint imaging for clustering studies with JWST
• Physical properties of the LBGs discovered by Euclid
(mass, SFR, kinematics, etc.) with ALMA, ELTs, SKA
• Lyα spectroscopy (re-ionization) with JWST and ELTs
• Open questions:
• Optimum Deep Field distribution (wedding cake vs.
uniform coverage)
• Observation settings
• Location of the Deep Fields
• etc.
The high-z star-formation history of the Universe
Smit et al (2012)
The highest SFR galaxies at any redshift are rare. Euclid
will be very good for finding these (at least candidates),
and out to z~4.3 detect them in [O II]3727.
Intermediate redshift
Euclid the surveyor
The multi-dimensional nature of galaxies
Large samples have allowed us to appreciate the multidimensionality of galaxy evolution.
If we can characterise a galaxy by a set of numbers:
G(Z, SFR, M⇤ , Mgas , , Vc , . . .)
We have found a large number of scaling relations,
4
M
/
V
Tully-Fisher:
c
4
L
/
Faber-Jackson:
Fundamental plane: log re = a log ⇥
b log µe +
Star-forming sequence: SFR / M⇤0.8
Mass-metallicity relation: Z ⇡ f (M⇤ , SFR, fgas )
Distribution functions
G(Z, SFR, M⇤ , Mgas , , Vc , . . .)
Large samples at low redshift show how some of these are
projections of higher dimensional distributions.
Mr – 5log10 h
–22
0.2 0.4 0.6 0.8
1
2
3
4
5
log10 [r /(h –1 kpc)]
50
0
0.5
1.0
1.0
0.5
0
5
5
4
4
3
3
2
2
1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
–20
–18
–18
–20
–22
Mr – 5log10 h
0.2 0.4 0.6 0.8
g–r
1
2
3
n
4
5
0
0.5
log10 [r50 /(h
–1
Blanton & Moustakas (2009)
Mr – 5log10 h
–22
g–r
g–r
–20
n
n
n
log10 [r50 /(h –1 kpc)]
–18
g–r
1.0
kpc)]
Mannucci et al (2010)
E.g.: Bi-modality with redshift
Muzzin et al (2013)
SDSS DR7:
Euclid will provide a major improvement - and for many
objects provide spectra. The number of galaxies required
goes up exponentially with the number of dimensions of
your distribution: Particularly important for the extremes of
distributions.
Euclid & distribution functions
Particular strengths:
Morphological information.
Lensing information.
Environment & clustering.
Very large numbers of sources
But:
Slit-less spectroscopy not optimal for dense regions
Low resolution spectroscopy
Optical imaging is not very deep.
Mostly a view of the stellar part of galaxies
Synergy: Complementary view of the galaxy population
Massive, passive galaxies
Y-band or redder is essential for finding passive
galaxies at z>1.5 (e.g. Daddi et al 2004). Euclid will also provide
sizes and morphologies for many of these.
Szomoru et al (2012)
NIR
VIS
Fontana et al (2009)
Massive galaxies form early
this work
Thomas et al. (2009)
Moresco et al (2011)
Because these
galaxies correspond
to rare peaks in the
density field, they can
offer stringent
constraints on galaxy
formation models and potentially on
cosmology.
But because they are
rare, and red we
need large area NIR
surveys - Euclid is
very well suited for
this.
High spatial resolution
Euclid the clear-eyed
Morphologies & associated science
Euclid @ z~1 will give similar images to SDSS @ z~0.1
Provides great opportunities for a large range of studies
and gain can be given as ~Area(Euclid)/Area(HST
imaging) Example: Galaxy mergers/Strong lensing.
Well known: Interactions/mergers increase the SFR
Quantitatively:
Very close pairs can show very
enhanced star formation (and it
is obscured), but for short
periods. Integrated over the
merger an enhancement of
~1.5-2 seems reasonable e.g.
Robaina et al (2009); Li et al (2008)
The total fraction of SF taking place
because of a merger is not high at low
redshift (rarity of mergers/short
duration). Robaina et al argue for ~8%.
Robaina et al (2009)
UV SFR
Galaxy mergers
Current surveys
(zCOSMOS, VVDS, etc) are
too small to help constrain
the physics.
Conselice et al (2009)
Time between mergers
But getting merger rates right is
proving very challenging:
Theoretical models differ by an
order of magnitude in their
predictions - the main obstacle:
Baryon physics (Hopkins et al 2010)
Galaxy mergers
Euclid will:
• Increase the sample size of z>1 spectroscopically
known mergers by ~3 orders of magnitude (much
more when combined with photo-zs)
• Provide high-resolution imaging and allow nonparametric merger classifications (e.g. CAS, Gini, M20)
• Provide physical properties for the systems by
combining spectroscopic and photometric
information.
• Allow us to study mergers as a function of
environment, mass, nuclear activity, ...
Strong lensing with Euclid
- see talk by L. Koopmans
Some Science Goals:
• Total-mass density profiles of galaxies in the inner several
effective radii
• WL of strong-lenses on larger scales.
• The stellar and dark matter mass fraction in the inner
regions of galaxies.
• The inner dark matter density distribution
• Scaling relations: e.g. Fundamental plane/TF
• The stellar IMF from combined lensing, dynamics & stellar
pop. analysis.
All as a function of redshift, galaxy mass, type, etc.
Galaxy formation as a whole
Euclid as a partner
Euclid is only part of the answer
• Visual & NIR imaging will be ground-breaking.
• But we will have limited colour information.
• The spectroscopic sample will be huge and will find
most extreme objects in the extra-galactic sky.
• But the resolution and spectral coverage is limited.
• We will provide environments and physical properties of
vast numbers of galaxies.
• But the information we will provide is based on the stellar
and ionized gas components of galaxies.
A general challenge for galaxy evolution:
The gas content (molecular + atomic) is rarely know for
large samples of galaxies.
The gas content is one key variable
Brinchmann et al (2013)
-2.0 -1.6 -1.2 -0.8 -0.3
• Difficult to get for large
samples.
0.5
-2.0 -1.5 -0.9 -0.4
0.05<z<0.09
0.1
0.7
1.2
ALFALFA 0.016<z<0.05
Log
*
9
8
0.5
6
7
Log rgas
6
• Important to also have
molecular gas content especially for spatially
resolved data.
7
8
7.5
10
7.9
9
10
Log M*
8.3
8.8
9.2
11
12 7
9.6 10.0
8
9
10
Log M*
11
12
9.8 10.0 10.2 10.4 10.6 10.8 11.0
0.05<z<0.09
ALFALFA 0.016<z<0.05
Log
*
9
10.28
• But it is clear that gas
content is a crucial extra
ingredient.
10
0.1
8
7
Log tR
6
7
8
9
10
Log M*
11
12 7
8
9
10
Log M*
11
12
Central to total depletion time.
Brinchmann et al (in prep)
12
Log MHI/SFR [years]
11
tU
10
Total
reservoir
9
8
Central
7
Leroy et al (2008)
Integrated disk
6
7
8
9
10
Log Mstar/Msun
How does this change with redshift?
Really need new facilities to address this.
11
Euclid in numbers
Per SKA1-survey
FoV
What
Euclid
Per SKA1-mid FoV
Galaxies at 1<z<3 with good
mass estimates and morph.
~2x108
~7x103
~3x105
Massive galaxies (1<z<3) w/
spectra
~few x 103
<<1
~1
Hα emitters/metal
abundance at z~1-2
~4x107/104
~103/<1
~5x104/10
Galaxies in massive clusters
at z>1
~(2-4)x104
~40 (per cluster)
~40
Type 2 AGN (0.7<z<2)
~104
<1
~10
Galaxy mergers
~105-few x 106
~30-300
~102-103
Strongly lensed galaxy-scale
lenses
~300,000
~10
~350
z > 8 QSOs
~30
<<1
<<1
Summary
• Euclid will provide a great inventory of galaxies in the Universe.
• The addition of high quality imaging will make strong and weak
lensing an integral part of galaxy evolution studies in general - the
implications of this have probably not yet been worked out in full.
• Euclid spectroscopy will be spectacular for finding rare objects and
provide fairly accurate spectroscopic redshifts.
• However the picture is very limited in wavelength range - and SKA
would provide complementary information for most science cases.
• For galaxy evolution adding the gas content of galaxies might be
the most dramatical addition - AGN identification would also be
very useful.
• Likewise Euclid will provide lists of extreme objects. This will be a
great catalogue for follow-up with SKA (and other facilities!).